On Rehearing.
BARHAM, Justice.Certiorari was granted to review a judgment of the Third Circuit Court of Appeal *1139which denied the workmen’s compensation claim of the • plaintiff Milton Bertrand, thereby reversing the trial court’s award of compensation for total permanent disability. The events which led up to the claim are well stated in our opinion on first hearing, and we adopt and incorporate in this opinion that portion of our original decision.
“The employer, Courville Concrete Company, was engaged in the manufacture of concrete culverts at Mamou in Evangeline Parish. Plaintiff, who was 57 years old in July 1964, had been employed with that firm for 16 years. As a principal part of his employment he was required to mix concrete, transport it by wheelbarrow, pour it into forms and otherwise perform heavy labor exposed to the heat of the sun in an unsheltered area of the manufacturing plant.
“As related in part by Dr. B. J. Manuel, plaintiff’s medical history discloses that Dr. Manuel performed surgery on him to repair bilateral herniae a number of years prior to July 9, 1964, at which time plaintiff’s heart was thoroughly examined and found to be normal and sound. He next consulted Dr. Manuel on July 9, 1964 for an episode of weakness, dizziness or near fainting which occurred while plaintiff was doing heavy work as a laborer with Courville Concrete Company. Dr. Manuel examined him at the Savoy Hospital and made an electrocardiogram, which he read and from which he concluded that plaintiff had a 'nodal tachycardia, a conduction defect impairing the heart’s response to impulses regulating its beat.
“He was put to bed, but after overnight rest and medication plaintiff was discharged from the hospital and returned home. Upon advice of his doctor, he did not resume work that summer. In the fall of the year, about September 14, 1964, because he was feeling well and the weather was cool, plaintiff was permitted by his doctor to return to his job with Courville Concrete Company. He worked there at his usual tasks without incident until June 1, 1965.
“While at work on June 1, 1965 plaintiff’s heart began to beat erratically and he almost ‘blacked out’ and fell to his knees, but he did not .lose consciousness. He returned to Dr. Manuel with essentially the same complaints made by him after the July 1964 episode. Another electrocardiogram was made in connection with his reexamination, medication was prescribed and he went home to bed. Two days later he again visited Dr. Manuel and reported he was feeling fine. At this time he was advised to stop working because Dr. Manuel thought the work with Courville was incompatible with his heart condition. The doctor felt that continued work in the hot sun might bring about a ‘full blown coronary’ and plaintiff’s death. * * * Plaintiff has not worked since.
*1141“Suit was instituted by plaintiff on September 9, 1965 claiming -compensation for total permanent disability, alleging that the episodes of July 9, 1964 and June 1, 1965 were both responsible for his condition. * * * [The claim based upon the 1964 episode was compromised.] Our only ■direct concern, therefore, is with the claim against Coal Operators Casualty Company and the episode of June 1, 1965.
“In defense of the claim, defendant contends that on June 1, 1965 plaintiff suffered an attack of angina pectoris from which he recovered almost immediately with no residual ill effects and the real cause of plaintiff’s disability, if any, is a ■disease of long standing known as arteriosclerosis [coronary sclerosis] which has become progessively worse. This condition, defendant contends, is neither caused nor aggravated by the episode of June 1, 1965 or by plaintiff’s work at any time.
“The central issue thus presented is whether there is any causal connection between the accident of June 1, 1965 and the disability of which plaintiff complains. * * * ”
It is not only admitted but clearly established that the plaintiff suffered an accident within the meaning of our workmen’s compensation law. Dr. Manuel, his family physician, has diagnosed the accident-induced injuries of both 1964 and 1965 as “nodal tachycardia”. Undoubtedly the electrocardiograms (EKG’s) upon the occasion of both accidents gave a reading of tachycardia (rapid heart beat). Both Dr. Manuel and Dr. Perron examined these EKG’s, and according to Dr. Perron’s testimony the reading of the July 9, 1964, EKG showed a heart rate of 152. Heart pulsations in excess of 100 are rapid (tachycardia) and below 60 slow (bradycardia). Dr. Manuel concluded from the tachycardia reflected by the EKG’s, other observable symptoms, and his particular knowledge as family physician that the plaintiff had a preexisting defective atrioventricular node,1 and that exertion caused a conduction fault in his heart. He testified that the first and second accidents were of similar nature and duration.
Dr. Craig saw the plaintiff Bertrand upon two occasions, one four months and the other over a year after the second accident. He took a history and each time performed a general examination which included an EKG. The EKG’s done upon *1143these occasions did not reflect rapid heart beat. Dr. Perron never saw the plaintiff, but testified upon hypotheses which related the facts and circumstances given in the testimony of the other doctors, with reliance upon the electrocardiograms made by Dr. Manuel in connection with both episodes. Both Dr. Perron and Dr. Craig were of the opinion that the plaintiff suffered from coronary sclerosis before both episodes. They admitted that the exertion upon each occasion caused the plaintiff to black out, become dizzy, and exhibit other symptoms, and it was their diagnosis that the arteries which fed the heart muscles were so sclerosed or restricted that during those periods of exertion they could not supply a sufficient quantity of blood, and that the plaintiff had either angina pectoris (“chest pain” from a coronary insufficiency) or possibly even a slight occlusion.2
It is not essential for this opinion and our ultimate determination to accept or reject either the diagnosis of Dr. Manuel or that of Drs. Craig and Perron. The plaintiff on June 1, 1965, had a preexisting disease of the heart, either a conduction problem caused by a defect in the atrioventricular node which improperly stimulated the ventricles of the heart, or coronary sclerosis which caused blood to be improperly fed to the heart muscles. Because of the exertion on that date the disease manifested itself in the manner previously described. All doctors now find him totally and permanently disabled and therefore precluded from returning to work because of this episode.3
Dr. Manuel did not testify that the 1965 episode aggravated the defective node. Drs. Craig and Perron did not testify that the 1965 episode aggravated or accelerated the arteriosclerotic heart disease. In fact, Dr. Craig testified that the extraordinary yet natural process of the body in repairing its defects apparently created newer and better channels or arteries to the heart muscle in the interval of one year between the plaintiff’s visits to him, and that this was reflected in the second EKG he made. What has happened to the plaintiff, according to all of the medical testimony, is that his total physical being and capacity have so changed that because of the symptoms exhibited (tachycardia or angina pectoris) and the preexisting disease (defective *1145atrioventricular node or coronary sclerosis) he cannot return to work of a character similar to that which he had successfully done without pain, complaint, or disability for 16 years before the first episode and for nine months after it. All would agree that it is likely that the symptoms (angina pectoris or tachycardia) will recur, producing in themselves pain, blackouts, and collapses. Under both diagnoses a “full blown coronary” or fatal occlusion is likely to result from the extreme exertion required by his work.
The Court of Appeal relied upon Seals v. Potlatch Forests, Inc., 151 So.2d 587 (La.App.3rd Cir. 1963), cert. den. 244 La. 398, 152 So.2d 63, and Nickelberry v. Ritchie Grocery Co., 196 La. 1011, 200 So. 330 (1941). If the Nickelberry case holds anything more than that plaintiff must discharge the burden of proving that an accident occurred, it is contained in the final paragraph of that opinion: “ * * * There must be an accident to furnish the basis of any such claim, that is to say, something sudden, undesigned or unexpected and that accident must either cause or aggravate the disease which is the cause of the disability.” (Emphasis supplied.) We do not believe the holding of that case is so limiting that only positive medical proof that a preexisting disease has been aggravated or a particular organ or organs of the body have been changed will sustain causation between accident and disability.
In a case such as the present one, where there is proof of an accident and of a following disability without any intervening cause, it is presumed that the accident caused the disability. The criterion for causal connection between the accident and the disability is: Has the accident changed the plaintiff’s condition so as to render him disabled and unfit for his former employment?
After the first accident which caused coronary insufficiency or “nodal tachycardia” the plaintiff was unable to work for a little over two months. Then with specific medical approval he returned to his job and actually performed the required hard physical labor for nine months, apparently asymptomatic of either disease or disability. All medical authority would now refuse to allow the plaintiff to return to work following, and because of, the second episode of tachycardia or angina pectoris. Not only do we presume but we must deduce that the second episode produced some change in the body of the plaintiff.
Medical experts are unable to determine or state the cause, the time of onset, the rate of or reason for acceleration or regression of arteriosclerosis or coronary *1147sclerosis. A plaintiff cannot be required to submit more proof'than is here offered that he has suffered disability by reason of a causally connected accident when any additional proof must come from a science whose practitioners admittedly lack complete and exact knowledge of many aspects of the disabling disease and whose views are often divergent and vacillating
Seals v. Potlatch Forests, Inc., supra, narrowly defined and overnicely refined the issue before the court. The legal criterion in compensation cases involving heart disease should be whether the accident caused a change in the employee’s physical condition which is disabling, and not whether the accident changed the diseased organ of the employee. The residual condition from an accidental injury which substantially increases the possibility of 'recurrence of a disabling or death-dealing episode is legally disabling and is compensable under our Workmen’s Compensation law.
Before this accident the plaintiff, though suffering from a cardiac or cardiovascular disease, exhibited no disabling symptoms of the disease, and adequately met the extreme physical demands of his employment. He was working with medical approval and with his employer’s full knowledge of his existing dormant disease. He has established an accident and his inability to return to work. Medical opinion recognizes that an accident (exertion) caused some kind of injury, that the .plaintiff is unable to return to work because of disability, and that the accident manifested the disability. We must therefore conclude that the accident has caused the termination of employment because of disability.
We have said repeatedly in workmen’s compensation cases that it matters not that the accident could have occurred at another place and at another time or even at any time. We have said' repeatedly that it is immaterial that the disability could have been brought on by causes other than trauma, if in fact trauma on the job which meets the standard of “accidental injury” within the Workmen’s Compensation Act is a disabling factor.
We conclude that the plaintiff has established the causal connection between the accident and the disability. He has persuaded us that but for the accident of June 1, 1965, he would not have the disability claimed. Had he died from that accident, all would admit that his death was compensable. We do not require his life or a degree of proof impossible to produce in the inexact state of medical knowledge.
We are concerned with the whole man and with the effect an accident in the course of employment has upon his ability to earn a living by doing work of a similar *1149nature. The courts should not offer to an accidentally injured employee the alternatives of either returning to work at unreasonable, even unconscionable risk or becoming dependent upon public support. Workmen’s compensation is a creation of the Legislature for the very purpose of localizing the economic responsibility in such a situation. Seals v. Potlatch Forests, Inc., supra, is specifically overruled.
The judgment of the Court of Appeal is reversed, and the judgment of the trial court is reinstated. All costs are to be paid by the defendant. The right to apply for rehearing is provided for in Rule XI, Section 3, of the Rules of this court.
. A.Y. node. There are two nodes (neurocardiac tissue), the sino-auricular node (“pacemaker”) which initiates the beat for the muscles of the atria, and the atrioventricular node which initiates the impulses which pass through the atrioventricular bundle, or “Bundle of His”, to the muscles of the ventricles and controls the discharge of blood to the lungs (from the right ventricle) and to the body generally (from the left ventricle). Dr. Manuel was not explicit as to which node he meant, but Dr. Perron referred to the atrioventricular node; we. therefore assume that it was the latter which concerned Dr. Manuel.
. Occlusion may be caused by a clot formation or concentration of excess material in the arteries (atheroma) which would stop the flow of blood. “Occlusion” must have been used loosely in the medical testimony since it literally means closure and produces an infarct (dead heart tissue), which is readily observed on an electrocardiogram; and yet it is denied there was any such showing.
. As the Court of Appeal properly reasoned, even Dr. Craig’s suggestion that “ * * * plaintiff could be given a series of ‘graded exercises’ under a doctor’s close observation to determine how much physical exertion his heart would tolerate” has the legal effect of classifying the plaintiff as disabled until such tests could be completed.