BEFORE THE IOWA INDUSTRIAL COMMISSIONER
 
         
 
         
 
         LARRY LAFOON,
 
         
 
              Claimant,
 
         
 
         VS.
 
                                                 File No. 830047
 
         AMHOF TRUCKING, INC.,
 
                                               A R B I T R A T I O N
 
                Employer,
 
                                               D E C I S I 0 N
 
         and
 
         
 
         AETNA CASUALTY & SURETY CO.,
 
         
 
              Insurance Carrier,
 
              Defendants.
 
         
 
         
 
                              STATEMENT OF THE CASE
 
         
 
              This is a proceeding in arbitration brought by claimant 
 
         Larry Lafoon against defendant employer Amhof Trucking, Inc., and 
 
         defendant insurance carrier Aetna Casualty & Surety Company to 
 
         recover benefits under the Iowa Workers' Compensation Act as the 
 
         result of an alleged injury sustained on August 8, 1986.  This 
 
         matter came on for hearing before the undersigned deputy 
 
         industrial commissioner in Davenport, Iowa, on May 31, 1989.  The 
 
         matter was considered fully submitted upon submission of two 
 
         depositions on June 5, 1989.
 
         
 
              The record in this proceeding consists of joint exhibits A 
 
         through D, defendants' exhibit 1, and the testimony at hearing 
 
         and by deposition of claimant.  The depositions of Peter S. 
 
         Jerome, M.D., and Phillip A. Habak, M.D., each taken May 26, 
 
         1989, have been identified as exhibits C and D.
 
         
 
                                      ISSUES
 
         
 
              Pursuant to the prehearing report submitted by the parties 
 
         and approved at hearing, the following issues have been 
 
         stipulated:  that an employment relationship existed between 
 
         claimant and employer at the time of the alleged injury; that if 
 
         claimant has sustained compensable permanent disability, he has 
 
         suffered an industrial disability to the body as a whole; that 
 
         the appropriate rate of compensation is $244.18 per week; that 
 
         affirmative defenses are waived;
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 2
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
         that the fees charged for medical services and supplies are fair 
 
         and reasonable and incurred for reasonable and necessary medical 
 
         expense.
 
         
 
              Issues presented for determination  include:  whether 
 
         claimant sustained an injury on August 8, 1986, arising out of 
 
         and in the course of his employment; whether the injury caused 
 
         temporary or permanent disability and the extent thereof; the 
 
         extent of claimant's entitlement to medical benefits; taxation of 
 
         costs.
 
         
 
                              REVIEW OF THE EVIDENCE
 
         
 
              Claimant testified to being an over-the-road truck driver 
 
         employed by defendant for approximately six  months prior to 
 
         August 6, 1986.  He described that day as hot and humid, well 
 
         over 90 degrees Fahrenheit.  He left Iowa for the state of 
 
         Georgia with a full load of aluminum coils.
 
         
 
              Claimant indicated his first stop was in Smyrna, Tennessee, 
 
         and his second stop in Chattanooga, Tennessee.  At each stop 
 
         claimant broke down the sides, tarp (approximately 300 pounds), 
 
         and steel bows from his trailer for unloading, then reinstalled 
 
         the equipment.  His third stop was in Atlanta, Georgia, which he 
 
         reached approximately 5:00 p.m., about 24 hours after leaving 
 
         Davenport, Iowa.  He again broke down and reinstalled his 
 
         equipment in temperatures of approximately 100 degrees 
 
         Fahrenheit.  He thereafter went to a truck stop, called and 
 
         reported his status to defendant, and slept.
 
         
 
              On the following morning claimant was to find a return load 
 
         in Chattanooga.  Amhof Trucking's dispatcher told him to hold off 
 
         and wait for a more profitable load, and even specifically 
 
         instructed claimant not to take a particular load. claimant 
 
         indicated that he took that load anyway because only a few were 
 
         available and he desired to return home for the weekend.  
 
         However, on cross-examination, claimant testified that the 
 
         dispatcher eventually gave him permission to take that load.  In 
 
         his deposition taken April 3, 1987, claimant testified:
 
         
 
              Q.  How did you go about finding a return load the 
 
              next morning?
 
         
 
              A.  On the return load board a load came up going 
 
              to Waterloo, Iowa from Chattanooga.
 
         
 
              Q.  So that morning did you drive up to
 
              Chattanooga?
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 3
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              A.  No. I didn't drive up to Chattanooga till in
 
              the afternoon because Amhof did not want me to
 
              take the load until it was an absolute last ditch
 
              effort.
 
         
 
              Q.  What do you mean?  I didn't understand that.
 
         
 
              A.  They didn't think I should jump right on that
 
              load.  They wanted me to wait and see if something
 
              better came up.
 
         
 
              Q.  So are you in contact with the local terminal
 
              trying to make a decision as to which load to
 
              bring back?
 
         
 
              A.  Yes.
 
         
 
              Q.  Why do they care about that?
 
         
 
              A.  Their truck, equipment.  They want to make the
 
              best money they can.
 
         
 
              Q.  I see.  Did Amhof caution you to wait till
 
              after noon then?
 
         
 
              A.  Yes.
 
         
 
              Q.  Did you get a better offer or did you end up
 
              taking that particular load?
 
         
 
              A.  I took that particular load.
 
         
 
         (Lafoon deposition, page 24, line 19 through page 25, line 21)
 
         
 
              At hearing, claimant testified that when he left Atlanta on 
 
         August 7 to pick up his load in Chattanooga he felt "drug out," 
 
         sick to his stomach, and suffered from what he identified as 
 
         heartburn.
 
         
 
              Claimant loaded two cranes in Chattanooga.  He broke down 
 
         one side of his truck to help load and helped chain the load down 
 
         in 102 degree temperatures.
 
         
 
              Claimant indicated that he thereafter drove north but 
 
         stopped in Franklin, Kentucky, to recuperate for a few hours.  He 
 
         continued to Hamburg, Indiana, where he  felt quite ill with 
 
         indigestion and heartburn.  After calling in to report his 
 
         position claimant slept in his cab the night of August 7.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 4
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              Claimant further testified on direct examination that he 
 
         intended to drive to the Davenport terminal on the morning of 
 
         August 8.  He awoke that morning feeling a little better, but 
 
         after taking a break while driving through the state of Illinois, 
 
         again felt ill.  He arrived at Davenport at approximately 5:00 
 
         p.m. and was off duty.
 
         
 
              Claimant indicated that he went to his wife's  parents 
 
         house to visit on the evening of August 8, played a dice game, 
 
         but left approximately 9:00 p.m. At that time he felt very hot 
 
         and had increased chest pains.  At home, he watched television 
 
         until approximately 10:00 p.m. before retiring.  His chest pain 
 
         worsened while he was in bed and began radiating to his arms at 
 
         approximately 11:00 p.m. to midnight.  Claimant called his 
 
         physician, Phillip Habak, M.D., and met the doctor at St. Luke's 
 
         Hospital where he  was taken by ambulance.  Claimant suffered a 
 
         myocardial infarction and underwent angioplasty at the hospital.
 
         
 
              Claimant agreed on direct examination that he first 
 
         suffered heart problems in 1978 when he was hospitalized for 
 
         tests for approximately five days.  Thereafter, he suffered no 
 
         chest or heart problems until March, 1986, when he visited the 
 
         emergency room at a local hospital due to chest pains.
 
         
 
              Claimant agreed that he has a family history of heart 
 
         disease.  His mother died at age 70 and his brother at age 47 of 
 
         heart problems.  Claimant denied that his father suffered from 
 
         heart disease.
 
         
 
              On cross-examination, claimant agreed that he suffered 
 
         chest pains in 1976.  He also agreed that he had been a cigarette 
 
         smoker for approximately 25 years at 2-3 packs per day until 
 
         1978.  He discontinued smoking then, but began again in 1979, 
 
         approximately eight months after quitting.  He at first smoked 
 
         less than one pack per day, but  gradually increased consumption 
 
         to two packs per day by 1984 or 1985 and continued smoking two 
 
         packs a day at the time of  the March, 1986 incident.  He again 
 
         briefly quit, but had resumed smoking at a two-pack per day level 
 
         by August,.1986.
 
         
 
              With respect to the sequence of events preceding 
 
         hospitalization, claimant indicating that he first felt ill after 
 
         leaving Atlanta on August 6.  In his deposition, claimant 
 
         testified that he was first ill on August 8.  He further 
 
         testified that his deposition testimony was due  to "bad 
 
         recollection," and that his recollection at time of hearing was 
 
         superior to his recollection on April 3, 1987.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 5
 
         
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              Claimant also testified that part of his reason for 
 
         stopping in Kentucky was due to a huge rainstorm that lasted over 
 
         two hours.
 
         
 
              Claimant also agreed that he had trouble sleeping and was 
 
         belching in Hamburg, Indiana, although this was inconsistent with 
 
         his deposition testimony.
 
         
 
              Claimant further testified that he felt better driving 
 
         between Illinois and Davenport.  He was specific in stating there 
 
         was no chance whatsoever that chest pain developed in the morning 
 
         of August 7 as opposed to the afternoon.
 
         
 
              In his deposition of April 3, 1987, claimant indicated that 
 
         after leaving Chattanooga with his return load, he stopped at a 
 
         truck stop on top of Mount Eagle, Tennessee for a couple of hours 
 
         due to rain and later waited approximately three more hours 
 
         because of rain in Franklin, Kentucky.
 
         
 
              When asked at deposition where he first began to experience 
 
         any kind of chest discomfort or any kind of feeling sick, 
 
         claimant answered Hamburg, Indiana on August 8 at 8:30 a.m. 
 
         shortly after breakfast.  Asked further how soon after eating 
 
         breakfast he began to feel symptoms of stomach illness, heartburn 
 
         and difficulty in swallowing, claimant responded that he felt 
 
         that way when he woke up.  He had not felt at all sick when going 
 
         to bed the night before, but was just extremely tired.  Claimant 
 
         indicated that while driving from Hamburg, Indiana, to Oakwood, 
 
         Illinois, he felt symptoms rather like influenza; those symptoms 
 
         persisted between Oakwood and Davenport, although they eased up 
 
         during that leg of the trip.
 
         
 
              Claimant further testified at deposition that he visited 
 
         his wife's parents after supper, staying until approximately 
 
         midnight.  After supper, he felt very ill and very hot with 
 
         sickness to the stomach, heartburn and headache.  He had felt 
 
         perhaps 50 percent better by the time he reached the Davenport 
 
         terminal earlier, and  deteriorated approximately 8:00 p.m.
 
         
 
              Claimant agreed that he had had a relatively light day 
 
         driving before his infarction because of the two lengthy layovers 
 
         due to weather, but further indicated that traffic and road 
 
         conditions were stressful.  The cab of his tractor was air 
 
         conditioned.
 
         
 
              Claimant also described his last trip in an undated letter 
 
         to Dr. Habak.  In that letter he stated that defendant really did 
 
         not want him to take the particular load but finally agreed.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 6
 
         
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              Mr. Lafoon's letter further stated:
 
         
 
              After loading I drove to Franklin Ky. through a
 
              bad thunderstorm.  I stayed there till the storm
 
              let up & drove on to Hamburg Ind. & slept for
 
              about 7 hrs.  I left Hamburg Ind. at 8:30 am on
 
              the 8th.  I drove for around 3 1/2 hours & stopped
 
              in Oakwood Ill. where I started feeling sick.
 
              After a 1/2 hr. break I continued home to Dav.  I
 
              got in to the company yard at 5:00  pm.  Went home
 
              & ate a little supper.  My wife wanted to go next
 
              door to her mothers so we walked over there.
 
              Their house is air cond.  We stayed there & played
 
              a dice game until around 11:00 pm   I was hot &
 
              sick so we walked home.  I was getting ready for
 
              bed when my chest pain got worse & my arms began
 
              getting numb.  My wife then called you.
 
         
 
              Emergency room records of St. Luke's Hospital show that 
 
         claimant appeared at 2:10 a.m. on August 9, 1986.  Initial 
 
         history was obtained of pain starting one hour before:  a heavy 
 
         squeezing sensation.  Chart notes indicated that claimant had 
 
         suffered severe crushing chest discomfort radiating to both arms 
 
         starting around 1:30 a.m., but had otherwise had no recent chest 
 
         discomfort.  A family history was that both parents died of 
 
         myocardial infarctions, as did a brother.  Dr. Habak's impression 
 
         was of severe coronary artery disease with diffuse disease of the 
 
         proximal segment of the right coronary artery culminating in near 
 
         total occlusion and complete occlusion of the circumflex coronary 
 
         artery; also, proximal lesions left anterior descending coronary 
 
         artery estimated at 40-50 percent and 50-60 percent respectively.
 
         
 
              Dr. Habak wrote claimant's attorney on September 25, 1986 
 
         in response to a letter of August 26.  Claimant's history was of 
 
         experiencing intermittent chest discomfort throughout the day 
 
         before admission and that he may have done heavy work loading and 
 
         unloading his truck that morning.  Noting that claimant had 
 
         suffered from a previous myocardial infarction in 1978, Dr. Habak 
 
         stated:
 
         
 
              To answer your question I do not believe that the
 
              patient's employment as a truck drivel lead (sic)
 
              to the coronary artery disease which in turn is
 
              responsible for the patient's heart attack.  It is
 
              possible, however, that the stress involved and
 
              continued heavy work after the onset of symptoms
 
              could have aggravated the patient's heart attack
 
              by imposing additional stress and strain on the
 
              heart and delaying prompt treatment.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 7
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              Dr. Habak's depositions of September 22, 1981 and May 26, 
 
         1989 are in evidence.  Dr. Habak is a board-certified physician 
 
         in internal medicine and cardiovascular disease.
 
         
 
              Dr. Habak testified in 1987 that claimant was first seen in 
 
         1978 for chest pain and that laboratory studies were consistent 
 
         with heart damage due to heart attack.  Claimant was in good 
 
         health on subsequent visits until his infarction of August 1986.  
 
         Dr. Habak had not seen claimant when he visited the emergency 
 
         room in March 1986.  In August, claimant's electrocardiogram at 
 
         the time of his emergency hospitalization showed changes of a 
 
         heart attack just then developing.  Claimant was treated in the 
 
         emergency room with a clot-disolving medication and then 
 
         underwent angioplasty.
 
         
 
              Dr. Habak was asked a hypothetical question by claimant's 
 
         attorney as to whether the heart attack  was casually related to 
 
         work.  The hypothetical question originally included the 
 
         assumption that claimant did heavy lifting and unloading the 
 
         morning or the morning before the infarction.  The record shows:
 
         
 
              Q.  (BY MR. McCARTHY) Well, let's assume that he
 
              traveled to Smyrna, Tennessee, on the 6th of
 
              August.  'Let's say this began on the 6th of
 
              August, the trip down South.  And that between
 
              on about the 6th of August he was involved in
 
              heavy exertion and continued -- let me also ask
 
              you to assume that the weather in the South at
 
              that time was approximately 100 degrees.  He
 
              continued to Atlanta, came back sometime in the
 
              morning of the 8th, which is 8th of August.  He
 
              woke up, became sick, continued to experience
 
              nausea and cotton mouth, indigestion.
 
         
 
              Do you have an opinion, then, to a reasonable
 
              degree of medical certainty as to whether the
 
              physical exertion caused his heart attack?
 
         
 
              A.  If a patient comes in with chest pain and the
 
              heart attack which developed as he was doing
 
              physical exertion, one may be able to implicate a
 
              casual relationship between the exercise and the
 
              heart attack.  In my opinion,,the heart attack
 
              precipitated that particular patient.  He may be
 
              prone to having the heart attack and may have had
 
              it at some other time, but it so happened that at
 
              that particular moment, the stress or strain of
 
              the exercise on top of the underlying coronary
 
              disease would have caused it.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 8
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
         
 
              I understand that Larry's chest pain developed
 
              several hours after the exertion, not during.  I
 
              think the exertion may have had something to do
 
              with the other pains he has had; for example, the
 
              indigestion. It may have been that he was having
 
              angina.  I don't know.  People with coronary
 
              disease do get angina when  they exert.  Sometimes
 
              the pain may feel like indigestion.  But it sounds
 
              to me that the heart attack started shortly before
 
              he came to the hospital, because of the changes we
 
              had on the cardiogram.
 
         
 
              Q.  How shortly are you talking about?
 
         
 
              A.   The pain started at 1:30, he told us, in the
 
              morning.  Or did he come at 1:30?  It started
 
              around 1:30 in the morning.
 
         
 
              Q.  Well, are you saying that the exertion could
 
              have caused the heart attack, then, given the
 
              underlying coronary disease here?
 
         
 
              A.  It would be difficult to implicate it, at
 
              least for me, to blame an exercise that was done
 
              12 hours or 24 hours earlier, with a heart attack
 
              developing later.
 
         
 
              Q.  What about the -- assume that he was driving,
 
              that he finished driving and got into Davenport at
 
              4:30 that afternoon of August the 8th, you saw him
 
              at 1:30 in the morning on August the 9th, and he
 
              got into Davenport just, oh, eight, nine hours
 
              before that, but the nausea, sickness had been
 
              with him for approximately 16 hours before that
 
              time. Does that assist you at all in determining
 
              whether or not the driving and the physical
 
              exertion could have caused the heart attack?
 
         
 
              A.  Well, I wish it was easy to answer that.  I
 
              think it would be a little surprising that he
 
              would have that many symptoms for so long and the
 
              heart attack would have just started out.  That
 
              would be the only thing.
 
         
 
         (Dr. Habak 1987 deposition, page 24, line 5 through page 26, line 
 
         18)
 
         
 
              And:
 
         
 
              Q.  Are you saying that you really can't tell,
 
              then?  Is that what you are telling me?  That you
 
              really can't say what the cause is, then?  The
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
         LAFOON V. AMHOF TRUCKING, INC.
 
         Page 9
 
         
 
         
 
              cause might have been something other than the
 
              physical, exertion?
 
         
 
              A.  I would have to say that it is something
 
              unrelated to the exertion.  I think the underlying
 
              disease, the coronary disease, was the main
 
              factor.  Why did he develop pain at that
 
              particular time and not, say, a week later or a
 
              week before?  We don't know.  But it is possible
 
              [sic] that if he had flu-like symptoms, that this
 
              may have played a factor somehow.
 
         
 
              Q.  Could the preexisting condition, the
 
              underlying disease, have accelerated the process
 
              which led to this heart attack at 1:30 in the
 
              morning on the 9th?
 
         
 
              A.  Yes, I think so.
 
         
 
              Q.  In other words, in some way, the underlying
 
              disease aggravated his condition which, in your
 
              opinion, could have then caused the heart attack?
 
         
 
              A.  Well, I think the underlying disease is the
 
              main cause of the heart attack.  If you have
 
              normal coronary arteries, he would not have had a
 
              heart attack.  It is unlikely that -- it is
 
              reported, but --
 
         
 
              Q.  But could the physical exertion and the
 
              underlying -- could the physical exertion, then,
 
              have accelerated the heart attack because of the
 
              underlying condition?
 
         
 
              A.  I cannot tell you for sure that it has not.
 
              It is possible.  If he was perspiring a lot with
 
              the exertion, if he became dehydrated -- the one
 
              thing that I am trying to associate with that is
 
              that something has affected the chemistry of the
 
              blood, the viscosity of the blood, that could have
 
              led to a clot because of the disease he had.  The
 
              artery must have been slightly narrowed but was
 
              not occluded.  It occluded around the time he
 
              started having the pain in the early morning.
 
         
 
         (Dr. Habak 1987 deposition, page 27, line 13 through page 29, 
 
         line 3)
 
         
 
              Dr. Habak also pointed out that the exertion may have made 
 
         conditions more favorable for the development of a heart attack 
 
         by affecting the viscosity of claimant's blood.
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 10
 
         
 
         
 
              Dr. Habak described how claimant's occlusion may have been 
 
         caused by an embolism which was successfully dissolved prior to 
 
         the angioplasty.  He did not believe that claimant had sustained 
 
         a total or nearly total occlusion of the right coronary artery 
 
         long before his admission, since occlusion should produce 
 
         immediate and severe symptoms.
 
         
 
              On cross-examination, Dr. Habak noted that family history 
 
         of coronary artery disease increased the likelihood that an 
 
         individual will similarly suffer coronary artery disease.
 
         
 
              Dr. Habak also commented on internist George River's 
 
         evaluation of claimant's EKG in March, 1986 to the effect that 
 
         comparison with a 1982 EKG strongly suggested that there had been 
 
         an intervening inferior infarction with major myocardial damage; 
 
         Dr. Habak noted that George River was qualified to interpret 
 
         EKG'S, but himself did not find the EKG that much different from 
 
         the 1978 EKG.
 
         
 
              Dr. Habak testified generally that the longer the interval 
 
         between an exertion and the development of symptoms, the less 
 
         likely there is that a casual relationship exists:
 
         
 
              Q.  Doctor, if the specific acts of exertion
 
              described by Mr. Lafoon where he breaks down his
 
              trailer occur, hypothetically, on day one, and
 
              then he rests all night, gets up the next morning
 
              and has some complaints of discomfort in his
 
              stomach, but basically does no specific exertion
 
              for the balance of that day other than simply
 
              driving his truck, and then symptoms develop early
 
              in the morning, 1:30 a.m., on what is essentially,
 
              then, the third day, is that lapse of time such
 
              that it makes it doubtful that the original
 
              exertion caused the heart attack?
 
         
 
              A.  I think it should.
 
         
 
         (Dr. Habak 1987 deposition, page 45, line 22 through page 46, 
 
         line 9)
 
         
 
              On redirect examination, Dr. Habak noted again that heart 
 
         pain and indigestion can simulate one another and that it is 
 
         possible for a person to have angina with indigestion which goes 
 
         away and then comes back subsequently as a heart attack.  He also 
 
         noted that the stress of driving a truck ("Maybe ignoring body 
 
         needs and keeping going and feeling tired and still driving and 
 
         missing meals") could possibly be sufficient to cause a heart 
 
         attack.
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 11
 
         
 
         
 
              Subsequently, Dr. Habak wrote claimant's attorney on March 
 
         18, 1988.  This apparently closely followed receipt of claimant's 
 
         undated letter. In pertinent part  he  wrote:
 
         
 
              Mr. Lafoon left Davenport on August 5th, driving
 
              his truck as far as Atlanta, Georgia.  Between
 
              that time and until August 7th, the patient was
 
              involved in various strenuous activities, at times
 
              under extreme heat with temperatures as high as
 
              100 [degrees].  The patient's activities included
 
              loading his truck, untarping the trailer, taking
 
              the sides off, removing blocking, loading and
 
              unloading the truck, etc.
 
         
 
              On October 7th [sic], the patient was under
 
              pressure to return to Davenport before the weekend
 
              on account of his birthday.  He spent several
 
              hours looking for a load back towards Iowa and
 
              when he eventually located one the Company
 
              initially refused allowing him to take this load.
 
              He became very upset and pleaded with them until
 
              they eventually agreed to allow him to return to
 
              Davenport with this particular load.  He then
 
              drove to Hamburg, Indiana, to pick up the load and
 
              left that town on the 8th at 8:30 AM.  Three hours
 
              later, he stopped in Oakwood, Illinois, with
 
              general malaise, being sick at the stomach and
 
              having symptoms of indigestion. He took a half
 
              hour break and was quickly on his way towards
 
              Davenport.  That evening, he had a little supper
 
              and went next door, to his wife's mother, where
 
              they stayed until around 11:00 PM.  At that time,
 
              he was not feeling well and noted that he was hot
 
              and sick. He then went back home and noted the
 
              discomfort in the chest to be progressive as he
 
              was getting ready to go to bed.  Eventually he was
 
              brought to the emergency room at St. Luke's
 
              Hospital with findings of a heart attack or
 
              myocardial infarction.
 
         
 
              * * *
 
         
 
              I also in Mr. Lafoon's account that the 2
 
              weeks prior to his heart attack he has worked long
 
              hours and had driven hundreds of miles.  He had to
 
              maintain a tight schedule in order to be in
 
              various locations for loading and unloading.
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              * * *
 
         
 
              Although we know that the patient has underlying
 
              coronary artery disease, we also know that he was
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 12
 
         
 
         
 
              feeling well and not [sic] experiencing any
 
              symptoms when he left Davenport on August 5th, on
 
              that last trip reaching as far as Atlanta,
 
              Georgia.  Mr. Lafoon also developed symptoms at
 
              1:00 PM, the afternoon of August 8th.  The
 
              symptoms are mainly described as indigestion,
 
              nausea, general malaise and feeling sick.  These
 
              were not quite relieved and he apparently did not
 
              feel well throughout the remainder of the day.  At
 
              11:00 PM, further symptoms occurred, eventually
 
              culminating with the onset of pain in the chest
 
              and the left arm.
 
         
 
              It is well known that a certain number of patients
 
              suffering from angina pectoris or myocardial
 
              infarctions present with symptoms of indigestion
 
              rather than clear cut chest pain.  In fact, many
 
              patients go around treating themselves with
 
              antacids and other digestive products prior to
 
              seeking medical attention for what is eventually
 
              discovered to be a cardiac or coronary event.
 
         
 
              It is safe to assume that there is a significant
 
              possibility that the patient's symptoms at 1:00,
 
              that afternoon, of August 8th could have
 
              represented angina pectoris or a warning symptom
 
              of what was yet to come.  Mr. Lafoon ignored these
 
              symptoms and pursued his intended goal to reach
 
              Davenport that day.  Accordingly, it is likely
 
              that, although the heart attack started in the
 
              early hours of August 9th, the patient's symptoms
 
              may well have started in the afternoon of the day
 
              before, about the time.he reached Oakwood,
 
              Illinois.
 
         
 
              Although the patient was not particularl exerting
 
              himself on August 8th, I note that during this
 
              particular trip there was a significant amount of
 
              physical exertion, long hours, exposure to high
 
              temperatures, insufficient sleep as well as
 
              excessive mental stress and frustrations.  Thus,
 
              these factors may have worked synergistically to
 
              significantly contribute to the patient's heart
 
              attack, (sic)  These events, although hot directly
 
              causing the heart attack, must have.played a
 
              significant role in contributing.or precipitating
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              the patient's illness.
 
         
 
              Dr. Habak testified further by deposition on May 26, 1989.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 13
 
         
 
         
 
              Dr. Habak testified in response to questioning by defense 
 
         counsel:
 
         
 
              [Q.] I want you to assume that Mr. Lafoon was off
 
              duty in Atlanta, Georgia, from 1:30 p.m. on August
 
              6, 1986, stayed overnight there, and was off duty
 
              through 10:30 a.m. on August 7th.  That is a total
 
              of 21 hours off duty.
 
         
 
              I want you to further assume that starting at
 
              10:30 in the morning he drove two hours and 15
 
              minutes to Chattanooga, at that point picked up a
 
              load, and then drove one hour and 15 minutes to a
 
              place called Monteagle, Tennessee, where he
 
              stopped for two hours due to weather I believe.
 
         
 
              I want you to further assume he then drove for
 
              another two hours and 30 minutes to a place called
 
              Franklin, Tennessee, where he again stopped either
 
              due to weather or road conditions, this time
 
              stopping for a total of three hours.
 
         
 
              Then I want you to assume that he drove two hours
 
              and 15 minutes to a place called Hamburg, Indiana,
 
              in other words, his driving, Doctor, that day was
 
              broken up far more than usual by these large rests
 
              or layovers due to weather or road conditions.
 
              Have you understood my basic hypothetical facts,
 
              Doctor?
 
         
 
              A.  Okay, yeah.
 
         
 
              Q.  My question is this: From what I have
 
              described to you, that is a pattern of driving
 
              then resting or being off the road for a period of
 
              time then driving again, does that sound to you in
 
              your experience like an activity that would be
 
              generating either very much stress or very much
 
              exertion for one's heart?
 
         
 
              A.  Generally not I think.
 
         
 
              Q.  I want to carry through this hypothetical just
 
              a moment, Doctor.  I want you to assume that when
 
              he got in Hamburg, Indiana, it was around  midnight
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              on August 8, 1986.  He then slept for eight hours
 
              in his sleeper cab until 8:30 in the morning.
 
         
 
              I want you to assume at that point he got up, he
 
              had a breakfast, and during the course of that
 
              breakfast, during the breakfast remembers feeling
 
              sick to my stomach, heartburn, and difficulty in
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 14
 
         
 
         
 
              swallowing, in other words, he felt that way while
 
              eating breakfast.
 
         
 
              I want you to assume he then drove for three and a
 
              half hours, took a coffee break for 30 minutes at
 
              a place called Oakwood, Illinois, at that point he
 
              said he felt like he had the flu.
 
         
 
              He then drove the rest of the way home to
 
              Davenport which was approximately four hours
 
              arriving at 4:30 p.m. and that by his recollection
 
              during the leg from Oakwood to Davenport he felt
 
              about 50 percent or half better.  Have you
 
              understood these additional hypothetical facts?
 
         
 
              A.  Yeah.
 
         
 
              Q.  Doctor, does the type of driving pattern that
 
              I have just described to you which added in an
 
              eight-hour sleep pattern, breakfast, some more
 
              driving broken up at least once by a 30 minute
 
              stop, does that in your experience sound like the
 
              type of activity that would be very stressful or
 
              very exertional to one's heart?
 
         
 
              A.  The activity by itself would probably not be
 
              stressful.
 
         
 
         (Dr. Habak 1989 deposition, page 61, line 22 through page 64, 
 
         line 11)
 
         
 
              Dr. Habak further testified that if he assumed that 
 
         symptoms developed at 1:00 p.m. rather than 8:30 p.m. on August 
 
         8, he could not be specific as to the most probable cause of 
 
         symptoms, although they could have been indigestion or an 
 
         ischemic episode.
 
         
 
              Dr. Habak testified:
 
         
 
              Q.  Is there any way, Doctor, as you testify today
 
              that with a reasonable degree of medical
 
              probability you could rule out the final deposits
 
              of sufficient plaque to cause an occlusion to this
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              artery during the night or at least to begin
 
              producing angina or angina pectoris during the
 
              night of August 7th to August 8th?.
 
         
 
              A.  That could have been initiated during the
 
              night, but they could also have occurred earlier.
 
         
 
              Q.  So in the spectrum of possibilities, I take it
 
              the deposits or the vasospasms could theoretically
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 15
 
         
 
         
 
                   occur on August 7th, they could occur during the
 
                   night of August 7th, or those events could occur
 
                   on August 8th itself, is that correct?
 
         
 
                   A.  One can say so, yes.
 
         
 
                   Q.  Is there any way, Doctor, with any kind of
 
                   reasonable medical probability that you can
 
                   pinpoint which of those three scenarios?
 
         
 
                   A.  I don't think we can answer that with
 
                   certainty; however, the kind of activities that
 
                   Mr. Lafoon related to in this letter on August
 
                   7th, including working hard in a temperature
 
                   reaching as much as 100 degrees, that could be a
 
                   factor that possibly may initiate the process that
 
                   would eventually lead to a heart attack.
 
         
 
         (Dr. Habak 1989 deposition, page 69, line 23 through page 70, 
 
         line 24)
 
         
 
                   And:
 
         
 
                   A.  Well, most of the time -- well, in a
 
                   significant number of patients, maybe about half
 
                   the patients who come with a heart attack, one can
 
                   obtain a history of symptoms that have occurred
 
                   earlier, past two or three days that could have
 
                   represented ischemic episodes but were ignored by
 
                   the patient and even though the timing of complete
 
                   and irreversible occlusion occurred when he came
 
                   to the emergency room that morning, it is likely
 
                   that he may have had either intermittent occlusion
 
                   with either spasm or a clot forming and through a
 
                   process we call lysis, regressing and then
 
                   reforming and that may have caused the initial
 
                   symptoms he described that morning or the morning
 
                   before.  Now, whether that is the case, I don't
 
                   know, but I think these are possibilities.
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
                 Q.  How do you rule out the fact he simply had
 
                 indigestion or a legitimate stomach or bowel
 
                 problem?
 
         
 
                 A.  I don't know.  I don't think we can answer
 
                 that for sure.
 
         
 
         (Dr. Habak 1989 deposition, page 72, line 9 through page 73, line 
 
         4)
 
         
 
              Peter S. Jerome, M.D., testified by deposition taken
 
         May 26, 1989.  Dr. Jerome specializes in internal medicine,
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 16
 
         
 
         
 
         pulmonary medicine and critical care medicine.  He saw claimant 
 
         once for evaluation on May 5, 1989.  In response to a 
 
         hypothetical question, Dr. Jerome testified:
 
         
 
              Q.  I want you to assume, Doctor, by way of
 
              hypothetical that Mr. Lafoon was off duty as a
 
              trucker in Atlanta, Georgia, from 1:30 p.m. on
 
              August 6, 1986, through 10:30 a.m. on August 7,
 
              1986, that is a total of 21 hours of off duty.  He
 
              then started to drive that morning and drove two
 
              hours and 15 minutes to Chattanooga, Tennessee,
 
              where he picked up a load to be brought back to
 
              Iowa.
 
         
 
              When the load was connected to his truck, he then
 
              drove an hour and 15 minutes to a place in
 
              Tennessee called Monteagle, he stopped for two
 
              hours we believe because of bad weather.  He then
 
              drove for another two hours and 30 minutes to
 
              Franklin, Tennessee, he then stopped for about
 
              three hours either due to bad weather or road
 
              conditions at that time.
 
         
 
              He then resumed driving and drove two hours and 15
 
              minutes to a place called Hamburg, Indiana.  At
 
              that point because of ICC rules he had to rest.
 
              He arrived at Hamburg around midnight, he slept
 
              for eight hours until 8:30 in the morning.
 
         
 
              He then upon awakening had breakfast and during
 
              the breakfast can recall feeling sick to his
 
              stomach, a sensation of heartburn, some difficulty
 
              in swallowing, the point being he felt that way
 
              while he was eating the breakfast.  He then
 
              proceeded to drive three and a half hours to a
 
              rest stop in Oakwood, Illinois.  He took a brief
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              rest of about 30 minutes.
 
         
 
              He remembers feeling somewhat like he had the flu
 
              or symptoms comparable to the flu.  He then
 
              completed the trip home to Davenport which took an
 
              additional four hours arriving at about 4:30 in
 
              the afternoon.  Have you understood those basic
 
              hypothetical facts?
 
         
 
              A.  That's correct.  That's similar to the story
 
              that was described to me.
 
         
 
              Q.  All right.  Doctor, I want to first of all
 
              concentrate on August 7th when he is down in
 
              Atlanta, Georgia.  From my hypothetical question
 
              did it sound like the periods of driving followed
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 17
 
         
 
         
 
         
 
              by forced layovers because of weather or bad roads
 
              would be the kind of exertion that within a
 
              reasonable degree of medical probability might
 
              either trigger or cause ultimately a myocardial
 
              infarction?
 
         
 
              A.  I believe this not to be likely.
 
         
 
         (Dr. Jerome deposition page 6, line 12 through page 8, line 10)
 
         
 
              Dr. Jerome explained that there are three basic mechanisms 
 
         for myocardial infarction:  coronary artery thrombosis, coronary 
 
         artery vasospasm, and coronary artery plaque rupture.  With 
 
         respect to a coronary vasospasm, he indicated that there is 
 
         ordinarily a close temporal relationship between suspected 
 
         exertional activity and an infarct.  However, there are 
 
         exceptions, for example if a patient has underlying angina or 
 
         coronary artery disease. Dr. Jerome further indicated that there 
 
         is a statistical correlation between heart attacks and 
 
         individuals with prior history of warning signs of angina.  He 
 
         further testified:
 
         
 
              Q.  How can either yourself today or better yet
 
              Dr. Habak when he actually works on Mr. Lafoon on
 
              August 9th, how can you say with any degree of
 
              certainty whether those symptoms were indicative
 
              of something going on in his intestines or his
 
              stomach as opposed to being early signs of a heart
 
              condition?
 
         
 
              A.  In retrospect, looking at the sequence of
 
              events, the symptoms could correlate with an early
 
              myocardial infarction and one could not exclude
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              that out as well as exclude gastrointestinal
 
              causes.
 
         
 
         (Dr. Jerome deposition, page 15, line 15 through page 16, line 1)
 
         
 
              Dr. Jerome also noted that claimant's morning infarction 
 
         could have been produced by any of the three possible heart 
 
         events he had described, although thrombosis and vasospasm would 
 
         be the most common types.  However, in either case, it would be 
 
         unusual for sickness to occur for a period of time and then 
 
         subside; there.is usually escalation of symptoms.
 
         
 
              Dr. Jerome was asked:
 
         
 
              Q.  Doctor, in terms of medical probability, based
 
              upon your review of the records, including your
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 18
 
         
 
         
 
              review of Dr. Habak's earlier deposition, do you
 
              have any opinion within a reasonable degree of
 
              medical certainty as to what was the most likely
 
              cause of Mr. Lafoon's myocardial infarction?
 
         
 
              A.  His underlying coronary artery disease.
 
         
 
              Q.  Why do you say that?
 
         
 
              A.  And natural progression of that disease.
 
         
 
              Q.   Why do you say that, Doctor?
 
         
 
              A.  He's had well established severe coronary
 
              artery disease since his late thirties and this
 
              would be a fairly natural progression of events.
 
         
 
              Q.  Would it be a natural progression, Doctor,
 
              irrespective of any particular exertional event or
 
              any particular amount of work?
 
         
 
              A.  Yes, it could be.
 
         
 
              Q.  Let's digress for just a second, Doctor.  If a
 
              person has underlying coronary artery disease and
 
              engages in strenuous labor in a hot environment,
 
              would you normally expect the onset of cardiac
 
              symptoms that were caused by the exertion to be
 
              fairly immediate, and by that I mean within a
 
              matter of perhaps three to four hours?
 
         
 
              A.  Yes.
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              Q.  Is the suspected relationship between exertion
 
              at any one point in time and a subsequent
 
              myocardial infarction weakened, is that temporal
 
              relationship weakened as the time span gets bigger
 
              and bigger?
 
         
 
              A.  Yes.
 
         
 
         (Dr. Jerome deposition, page 21, line 14 through page 22, line 
 
         21)
 
         
 
              Dr. Jerome testified further:
 
         
 
              Q.  If Mr. Lafoon had a risk factor of family
 
              history of heart problems as I have described as
 
              well as a history of smoking and then as a third
 
              factor had a known or demonstrable prior history
 
              of some ischemic events, does that make him a
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 19
 
         
 
         
 
              prime candidate, Doctor, to have a myocardial
 
              infarction?
 
         
 
              A.  Yes.
 
         
 
              Q.  Is there any relative weighting or relative
 
              ranking in terms of seriousness between the family
 
              history, the smoking, or the prior history of
 
              ischemic events as to what is the most serious
 
              risk factor?
 
         
 
              A.  You are talking about two factors that cause
 
              coronary disease, coronary artery disease that has
 
              been established; but persistent smoking on top of
 
              an established diagnosis tends to advance this
 
              risk for further events.
 
         
 
              Q.  Just a couple more questions, Doctor.  If a
 
              patient has known or demonstrable atherosclerotic
 
              conditions, particularly if they involve the
 
              coronary artery, can those conditions progress on
 
              their own to the point where there is a serious
 
              blockage or partial occlusion of the coronary
 
              artery?
 
         
 
              A.  Yes.
 
         
 
              Q.  Can they progress on their own in the absence
 
              of any specific trauma or exertion and lead to a
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              partial or total occlusion?
 
         
 
              A.  Yes.
 
         
 
              Q.  Would there be anything at all unusual or out
 
              of the ordinary for that kind of progression to
 
              occur in an individual like Mr. Lafoon?   By that I
 
              mean if he already has the condition, if he has
 
              the hereditary risk factor, and if he has a
 
              history of smoking, would there be anything at all
 
              out of the ordinary about an individual like that
 
              developing a heart attack that was related to
 
              natural progression of the atherosclerotic
 
              disease?
 
         
 
              A.  That would be an expected event.
 
         
 
              Q.  Doctor, would you have an opinion based upon a
 
              reasonable degree of medical probability as to
 
              whether an individual who exhibits Mr. Lafoon's
 
              history and exhibits his cardiac makeup would be
 
              likely to develop a myocardial infarction in the
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 20
 
         
 
         
 
              absence of any specific exertion or any specific
 
              work or any specific overload?
 
         
 
              A.  He would run a fairly high risk of development
 
              of myocardial infarction despite, you know, heavy
 
              exertion factors.
 
         
 
              Q.  From the history we have described, Doctor,
 
              from the hypothetical history I have described to
 
              you do you have an opinion within a reasonable
 
              degree of medical probability as to whether Mr.
 
              Lafoon's heart attack was related to any specific
 
              work event?
 
         
 
              A.  Historically that is not clear at all.
 
         
 
              Q.  Given his risk factors is it just as likely or
 
              probable that his heart attack could be a
 
              developmental or a progressive result of his
 
              atherosclerotic condition?
 
         
 
              A.  Yes.
 
         
 
         (Dr. Jerome deposition, page 28, line 2 through page 30, line 14)
 
         
 
                           APPLICABLE LAW AND ANALYSIS
 
         
 
              An employee is entitled to compensation for any and all 
 
         personal injuries which arise out of and in the course of the 
 
         employment.  Section 85.3(l).
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              Claimant has the burden of proving by a preponderance of 
 
         the evidence that he received an injury on or about August 8, 
 
         1986 which arose out of and in the course of his employment.  
 
         McDowell v. Town of Clarksville, 241  N.W.2d  904 (Iowa 1976); 
 
         Musselman v. Central Telephone Co., 261 Iowa 352, 154 N.W.2d 128 
 
         (1967).
 
         
 
              The injury must both arise out of and be in the course of 
 
         the employment.  Crowe v. DeSoto Consol. Sch. Dist., 246 Iowa 
 
         402, 68 N.W.2d 63 (1955) and cases cited at pp. 405-406 of the 
 
         Iowa Report.  See also Sister Mary Benedict v. St. Mary's Corp., 
 
         255 Iowa 8417, 124 N.W.2d 548 (1963) and Hansen v. State of Iowa, 
 
         249 Iowa 1147, 91 N.W.2d 555 (1958).
 
         
 
              The words "out of" refer to the cause or source  of  the 
 
         injury.  Crowe v. DeSoto Consol. Sch. Dist., 246 Iowa 402, 68 
 
         N.W.2d 63 (1955).
 
         
 
              The words "in the course of" refer to the time and place 
 
         and circumstances of the injury.  McClure v. Union
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 21
 
         
 
         
 
         et al. Counties, 188 N.W.2d 283 (Iowa 1971); Crowe v. DeSoto 
 
         Consol. Sch. Dist., 246 Iowa 402, 68 N.W.2d 63 (1955).
 
         
 
              "An injury occurs in the course of the employment when it 
 
         is within the period of employment at a place the employee may 
 
         reasonably be, and while he is doing his work or something 
 
         incidental to it."  Cedar Rapids Comm. Sch. Dist. v. 
 
         Cady, 278 N.W.2d 298 (Iowa 1979), McClure v. Union et al. 
 
         Counties, 188 N.W.2d 283 (Iowa 1971); Musselman v. Central 
 
         Telephone Co., 261 Iowa 352, 154 N.W.2d 128 (1967).
 
         
 
              The supreme court of Iowa in Almquist v. Shenandoah 
 
         Nurseries, 218 Iowa 724, 731-32, 254 N.W. 35, 38 (1934) discussed 
 
         the definition of personal injury in workers, compensation cases 
 
         as follows:
 
         
 
              While a personal injury does not include an
 
              occupational disease under the Workmen's
 
              Compensation Act, yet an injury to the health may
 
              be a personal injury.  [Citations omitted.]
 
              Likewise a personal injury includes a disease
 
              resulting from an injury....The result of changes
 
              in the human body incident to the general
 
              processes of nature do not amount to a personal
 
              injury.  This must follow, even though such
 
              natural change may come about because the life has
 
              been devoted to labor and hard work.  Such result
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              of those natural changes does not constitute a
 
              personal injury even though the same brings about
 
              impairment of health or the total or partial
 
              incapacity of the functions of the human body.
 
         
 
                 ....
 
         
 
              A personal injury, contemplated by the Workmen's
 
              Compensation Law, obviously means an injury to the
 
              body, the impairment of health, or a disease, not
 
              excluded by the act, which comes about, not through the
 
              natural building up and tearing down of the human body,
 
              but because of a traumatic or other hurt or damage to
 
              the health or body of an employee.  [Citations
 
              omitted.]  The injury to the human body here
 
              contemplated must be something, whether an accident or
 
              not, that acts extraneously to the natural processes of
 
              nature, and thereby impairs the health, overcomes,
 
              injures, interrupts, or destroys some function of the
 
              body, or otherwise damages or injures a part or all of
 
              the body.
 
         
 
              The claimant has the burden of,proving by a preponderance 
 
         of the evidence that the injury on or about August 8, 1986 is 
 
         casually related to.the disability on
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 22
 
         
 
         
 
         which he now bases his claim.  Bodish v. Fischer, Inc., 257 Iowa 
 
         516, 133 N.W.2d 867 (1965). Lindahl v. L. 0. Boggs, 236 Iowa 296, 
 
         18 N.W.2d 607 (1945).  A possibility is insufficient; a 
 
         probability is necessary.  Burt v. John Deere Waterloo Tractor 
 
         Works, 247 Iowa 691, 73 N.W.2d 732 (1955).  The question of 
 
         casual connection is essentially within the domain of expert 
 
         testimony.  Bradshaw v. Iowa Methodist Hospital, 251 Iowa 375, 
 
         101 N.W.2d 167 (1960).
 
         
 
              However, expert medical evidence must be considered with 
 
         all other evidence introduced bearing on the casual connection.  
 
         Burt, 247 Iowa 691, 73 N.W.2d 732.  The opinion of experts need 
 
         not be couched in definite, positive or unequivocal language.  
 
         Sondag v. Ferris Hardware, 220 N.W.2d 903 (Iowa 1974).  However, 
 
         the expert opinion may be accepted or rejected, in whole or in 
 
         part, by the trier  of fact. Id. at 907.  Further, the weight to 
 
         be given to such an opinion is for the finder of fact, and that 
 
         may be affected by the completeness of the premise given the 
 
         expert and other surrounding circumstances.  Bodish, 257 Iowa 
 
         516, 133 N.W.2d 867.  See also Musselman v. Central Telephone Co.
 
         , 261 Iowa 352 , 154 N.W.2d 128 (1967).
 
         
 
              While a claimant is not entitled to compensation for the 
 
         results of a preexisting injury or disease, the mere existence at 
 
         the time of a subsequent injury is not a defense.  Rose v. John 
 
         Deere Ottumwa Works, 247 Iowa 900, 908, 76 N.W.2d 756, 760-61 
 
         (1956).  If the claimant had a preexisting condition or 
 
         disability that is aggravated, accelerated, worsened or lighted 
 
         up so that it results in disability, claimant is entitled to 
 
         recover.  Nicks v. Davenport Produce Co., 254 Iowa 130, 115 
 
         N.W.2d 812, 815 (1962).
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              Claimant originally testified that he took a load 
 
         apparently in contravention of dispatcher's orders in order to 
 
         return to Iowa to be home for the weekend.  However, on 
 
         cross-examination, he appeared to indicate that he did have 
 
         permission to take the load he actually did after noon.  No 
 
         contrary evidence was produced by defendants.  It is held that 
 
         claimant has established that he was in the course of his 
 
         employment where symptoms occurred while driving on his last trip 
 
         before the myocardial infarction.
 
         
 
              But, was the eventual myocardial infarction an injury 
 
         arising out of claimant's employment?. As has been seen, the 
 
         question of casual relationship is largely in the sphere of 
 
         expert testimony.  The evidence shows that claimant had 
 
         preexisting coronary artery disease.  Quoting 1A [sic] Larson 
 
         Workmen's Compensation Law, section 38.83, the Iowa court in 
 
         Briarcliff College v. Campolo, 360 N.W.2d 91 (Iowa 1984) noted 
 
         that a compensable injury may result when heavy
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 23
 
         
 
         
 
         exertions ordinarily required by work are superimposed upon a 
 
         defective heart, aggravating or accelerating the preexisting 
 
         condition or "when the medical testimony shows an instance of 
 
         unusually strenuous employment exertion, imposed upon a 
 
         preexisting diseased condition."  Claimant must prove by a 
 
         probability, not a possibility, that some employment incident or 
 
         activity caused his coronary event.  Because he had a preexisting 
 
         heart condition, he must prove that he suffered an aggravation to 
 
         his already impaired physical condition.  Id.
 
         
 
              The medical opinions are in conflict, as are claimant's 
 
         various recitations of his history preceding the myocardial 
 
         infarction.
 
         
 
              At hearing, claimant indicated that when he left Atlanta on 
 
         August 7 on his way to Chattanooga, he suffered from flu-like 
 
         symptoms and heartburn.  He loaded and chained in Chattanooga and 
 
         felt ill in Franklin, Kentucky and Hamburg, Indiana.  After 
 
         sleeping in his cab, he felt a little better on the morning of 
 
         August 8, but felt ill again while driving through Illinois.
 
         
 
              In his deposition, claimant testified that his first 
 
         manifestations of illness were on August 8, one day later than 
 
         the version of events testified to at hearing.  He specified at 
 
         deposition that he first experienced any kind of discomfort or 
 
         sickness in Hamburg, Indiana on August 8 at 8:30 a.m., shortly 
 
         after breakfast.  He had felt approximately 50 percent better by 
 
         the time he reached Davenport later that day.
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
              In his letter to Dr. Habak, claimant indicated that he 
 
         began feeling ill in Oakwood, Illinois, about three and one-half 
 
         hours after leaving Hamburg, Indiana.  Given these three 
 
         conflicting versions, two of which were given under oath, it is 
 
         difficult to a high degree to accurately determine where and when 
 
         claimant first developed symptoms of flu-like malaise or 
 
         heartburn.  Admission notes of the hospital show that claimant 
 
         did not have chest discomfort until shortly before admission.
 
         
 
              Dr. Habak wrote on September 25, 1986 to note that 
 
         claimant's employment did not lead to the coronary artery 
 
         disease, but that it was "possible" that stress and continued 
 
         heavy work after the onset of symptoms could have aggravated a 
 
         heart attack by imposing additional stress and strain and by 
 
         delaying prompt treatment.  In his 1987 deposition, Dr. Habak 
 
         found it difficult to implicate an exercise that was done 12 or 
 
         24 hours earlier with a heart attack developing later.  In 
 
         essence, he found no casual connection between the work and the 
 
         infarction.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 24
 
         
 
         
 
              Dr. Habak's letter to claimant's attorney of March  18, 
 
         1988 (apparently following claimant's undated letter) was based 
 
         on claimant developing symptoms on the afternoon of August 8.  He 
 
         felt there was a "significant possibility" that claimant's 
 
         symptoms of that afternoon could have represented angina pectoris 
 
         or a warning symptom of what was yet to come.  It was "likely" 
 
         that although the heart attack started in the early hours of 
 
         August 9, the symptoms may well have started in the afternoon of 
 
         the day before when claimant reached Oakwood, Illinois.  Dr. 
 
         Habak wrote that claimant's significant amount of physical 
 
         exertion, long hours, exposure to high temperatures, insufficient 
 
         sleep and excessive mental stress and frustrations may have 
 
         worked synergistically to significantly contribute to the heart 
 
         attack. "These events, although not directly causing the heart 
 
         attack, must have played a significant role in contributing or 
 
         precipitating the patient's illness."
 
         
 
              In his 1989 deposition, Dr. Habak, given a different 
 
         hypothetical scenario closer to claimant's testimony at trial, 
 
         conceded that claimant's activity "would probably not be 
 
         stressful."  In essence, he was able to discuss casual 
 
         relationship only in terms of possibility, not  probability. 
 
         Asked how he could rule out the fact that claimant had simply 
 
         suffered indigestion or legitimate stomach or bowel problems 
 
         while on the road, Dr. Habak responded:  "I  don't know.  I don't 
 
         think we can answer that for sure."
 
         
 
              Dr. Jerome testified after evaluating claimant that it was 
 
         unlikely that periods of driving followed by forced layovers 
 
         because of weather or bad roads would be the kind of exertion 
 
         that within a reasonable degree of medical probability might 
 
         trigger or ultimately cause a myocardial infarction.  He noted 
 
         that claimant's early symptoms could correlate with an early 
 
         myocardial infarction, but that one could not exclude 
 
         gastrointestinal causes.  He specifically pointed out that one 
 
         would normally expect the onset of cardiac symptoms caused by 
 
         exertion to be fairly immediate, perhaps within a matter of 3-4 
 
         hours.  He opined (in response to leading questions) that the 
 
         relationship between exertion and infarction weakens as the 
 
         intervening time span increases.  In general, he opined that it 
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         is unclear that claimant's heart attack was related to any 
 
         specific work event and that it was just as likely or probable 
 
         that the infarction was a developmental or progressive result of 
 
         his atherosclerotic condition.  He further noted claimant's 
 
         family history of heart disease and history of smoking.
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              As has been seen, claimant's history of the events 
 
         preceding his infarction has varied from time to time.  Dr. 
 
         Habak's opinion has varied with the history he was given.  At his 
 
         latest deposition, Dr. Habak did not testify to a
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 25
 
         
 
         
 
         reasonable degree of medical certainty that any work incident was 
 
         casually related to the infarction.  Dr. Jerome was of the view 
 
         that no such casual relationship existed.  On balance, the 
 
         undersigned concludes that claimant has failed to meet his burden 
 
         of proof in establishing that his myocardial infarction of August 
 
         9, 1986 was casually related to his work or that this incident 
 
         arose out of the employment.
 
         
 
              Therefore, other issues are moot.
 
         
 
                                 FINDINGS OF FACT
 
         
 
              THEREFORE, based on the evidence presented, the following 
 
         ultimate facts are found:
 
         
 
              1. When returning with a load to the state of Iowa in 
 
         August, 1986, claimant was driving with permission of his 
 
         dispatcher.
 
         
 
              2. On August 7 and 8, 1986, while driving truck, claimant 
 
         developed symptoms such as indigestion and heartburn.
 
         
 
              3. Claimant has given contradictory versions of when his 
 
         symptomatology arose.
 
         
 
              4. Claimant suffered a myocardial infarction on the early 
 
         morning of August 9, 1986.
 
         
 
              5. Claimant's driving activities on the three days prior to 
 
         his infarction included periods of strenuous work and extended 
 
         periods of rest, although temperatures were high.
 
         
 
              6. Claimant has failed to establish that his myocardial 
 
         infarction is casually related to any work incident or exertion.
 
         
 
                                CONCLUSIONS OF LAW
 
         
 
              WHEREFORE,.based on the principles of law previously cited, 
 
         the following conclusions of law are made:,
 
         
 
              1. Claimant was in the course of.his employment when he 
 
         developed symptoms on August 7 and/or 8, 1986, which may or may 
 
         not have been indicative of his subsequent myocardial infarction.
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
              2. Claimant has failed to establish that his myocardial 
 
         infarction arose out of his employment or is casually related to 
 
         the same.
 
         
 
         
 
         
 
         LAFOON v. AMHOF TRUCKING, INC.
 
         Page 26
 
         
 
         
 
                                      ORDER
 
         
 
              THEREFORE, IT IS  ORDERED:
 
         
 
              Claimant shall take nothing from this proceeding.
 
         
 
              Costs of this action are taxed to defendants pursuant to 
 
         Division of Industrial Services Rule 343-4.33.
 
         
 
               Signed and filed this 25th day of April, 1990.
 
         
 
         
 
         
 
                                               DAVID RASEY
 
                                               DEPUTY INDUSTRIAL 
 
         COMMISSIONER
 
         
 
         
 
         
 
         Copies To:
 
         
 
         Mr. Michael J. McCarthy
 
         Mr. Lawrence J. Lammers
 
         Attorneys at Law
 
         701 Kahl Building
 
         Davenport, Iowa  52801
 
         
 
         Mr. Thomas N. Kamp
 
         Attorney at Law
 
         600 Davenport Bank Building
 
         Davenport, Iowa  52801
 
         
 

 
         
 
 
 
 
 
 
 
 
 
 
 
         
 
 
         
 
 
 
 
 
 
 
 
 
 
 
                                            1108.10, 1402.30
 
                                            Filed April 25, 1990
 
                                            DAVID RASEY
 
         
 
                     BEFORE THE IOWA INDUSTRIAL COMMISSIONER
 
         
 
         
 
         LARRY LAFOON,
 
         
 
              Claimant,
 
         
 
         VS.
 
                                                 File No. 830047
 
         AMHOF TRUCKING, INC.,
 
                                              A R B I T R A T I 0 N
 
              Employer,
 
                                                 D E C I S I 0 N
 
         and
 
         
 
         AETNA CASUALTY & SURETY CO.,
 
         
 
              Insurance Carrier,
 
              Defendants.
 
         
 
         
 
         1108.10, 1402.30
 
         
 
              Claimant developed flu-like symptoms for one or two days 
 
         (his.versions varied) while driving truck, later suffered a 
 
         myocardial infarction at home.  Medical evidence was in conflict.  
 
         It was found that claimant failed to prove
 
         the infarction arose out of or was casually related to 
 
         employment.