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Dissecting Aneurysm of the Aorta *
DISS ECTlNG ANEURYSM OF THE AORT A* EMMET B. BAY, M.D.t DISSECTING aneurysm of the aorta rivals syphilis in the number and variety of other disease entities which it may simulate and with which it may be confused. In the large and growing literature:!: on the subject it is apparent that it is most often misdiagnosed coronary thrombosis. It has also been mistaken for syphilitic aortitis, cerebral vascular accidents, mediastinal tumors, pneumonia, diaphragmatic hernia, cholelithiasis, pancreatitis, nephrolithiasis, ruptured peptic ulcer, mesenteric thrombosis, embolic occlusion of the arteries in the extremities and disease of the lower spinal cord. The incidence of dissecting aneurysm in general is not available but though low, it appears to be large enough to warrant inclusion in the thinking of a physican attempting the diagnosis of an acute, severe chest or back pain in an older patient. As a cause of sudden death, Mote and Carr1 found it in about 1.1 per cent of nontraumatic coroner's cases. The number of cases correctly diagnosed ante mortem is increasing rapidly and represents from 10 to 30 per cent of most of the series reported.
PRECIPITATING FACTORS
It occurs much more frequently in men than in women and usually in patients with pre-existing hypertension. Syphilis of the aorta is not an important predisposing factor nor is external trauma as frequent a precipitating factor as was formerly thought. The role of unusual exertion in its onset is not yet a settled point. Cherry and Cherry2 believe that on a statistical ba~is exer• From the Department of Medicine, University of Chicago School of Medicine. t Professor of Medicine, University of Chicago School of Medicine. :t: No attempt is made to be all-inclusive in the appended bibliography. For an excellent historical account of our knowledge of this disease and a good bibliography the reader is referred to an article by Flaxman in the American Heart Journal, 24:654, 1942. . 112
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tion is a coincidental rather than a necessary precipitating factor. This, of course, has important medicolegal connotations. There are case histories available, however, which suggest strongly that, in the presence of a background for trouble, excessive exertion is dramatically related to the beginning of symptoms. ETIOLOGY AND PATHOLOGY
The pathogenesis probably includes two main modes of development. Erdheim's3 medial necrosis is the primary lesion in some cases and results in dissection by virtue of hematoma formation within the wall of the aorta brought about by rupture of the vasa vasorum. This subsequently may break through the intima in one or more places. Primary rupture of the intima and subsequent dissection of the media also occur in the absence of pre-existing medial necrosis. Such intimal tears may occur without dissection and have . been labeled incomplete rupture of the aorta by Gallavardin and Gravier4 and Peery.5 The latter states that this lesion is probably IIlore frequent than dissecting aneurysm although it has not so far been diagnosed ante mortem. Secondary pathologic changes serve to explain many of the mistakes in ante-mortem diagnoses, as was pointed out by Crowell. 6 The intimal tear, with or without medial necrosis, may occur at any point along the aorta but more often is found in the ascending aorta near the aortic ring and frequently in that portion of the wall within the reflected pericardial sac. The subsequent dissection may travel in either or both directions up and down the aorta as well as around it. Its encroachment on the branches of the aorta and on the aortic ring produces the varied symptomatology which at once makes its diagnosis possible in an increasing number of cases and serves to confuse it with the wide range of clinical entities cited above. It may, for example, result in a suddenly developing aortic insufficiency by one of three mechanisms described in the literature. It may result in the partial or complete occlusion of one or more coronary, subclavian, carotid, intercostal, renal, mesenteric or common ili3;c arteries. The vessel or vessels involved determine the signs and symptoms produced. Death may come suddenly when the dissecting aneurysm or the incomplete rupture of the aorta breaks through the adventitia. There are cases on record, however, in which survival of
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such an accident has occurred, at least for a few days. The rupture may occur into the pericardial sac with resulting cardiac tamponade or into the pleural space, the mediastinum, the abdominal cavity, the retroperitoneal tissues, or even into the gast:ro-intestinal tract and be accompanied by the vomiting of blood. DIAGNOSIS
SYMPToMs.-Although "silent" dissections of the wall of the aorta are thought to occur, by far the majority of those which result in survival are accompanied by pain. This pain is often excruciating, unrelieved by large doses of morphine. It frequently resembles the distress in the chest produced by coronary thrombosis but does not radiate to the arms characteristically. It does tend to radiate to the back between the scapulae and sometimes to the neck and head, lower back and legs. Occasionally it travels, hour by hour or day by day, down the back from the neck to the legs. It may be throbbing in character and intermittent, lasting a few hours at a time. Other symptoms, not invariably present, include dyspnea, vomiting, loss of consciousness, transient paralysis of the legs and in some instances those of heart failure. Rarely, hematuria has been prominent enough to suggest primary renal pathology.7 PHYSICAL FINDINGs.-On physical examination there may be little to find which differs from the pre-existing record when such is available. The blood pressure, usually elevated previously, does not drop unless the patient develops the signs and symptoms of shock or unless the orifice or first portion of the artery in the extremity tested has been involved in the dissection. In the latter instance, the drop in blood pressure in one or two extremities and not in the others, in the presence of chest and back pain, points the way to a correct diagnosis. The sudden development of the diastolic murmur of aortic insufficiency accompanied by the increased pulse pressure and other peripheral manfestations of this lesion within a day or two after the onset of chest and back pain is another clue strongly suggestive of the true nature of the pathology present when it occurs. Transient changes in the strength and reflexes of one or both lower extremities when other symptoms of a dissecting aneurysm exist help to make the diagnosis definite. s
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In those instances in which the patient lives for months or years after the onset, there may be remarkably little to show for it on physical examination or the signs of gradually developing heart failure may supervene. X-RAY STUDy.-Among the laboratory procedures, roentgenography and fluoroscopy of the chest are the most helpful. A generalized widening of the aorta, especially in oblique views, is the characteristic finding. Occasionally this may include a widening of the vessels of the upper mediastinum. ELECTROCARDIOGRAPHY.-The electrocardiogram usually does not change materially unless the coronary orifices are involved in the dissection. This negative finding is of some help in the differential diagnosis. In the event the coronaries are obstructed, the electrocardiogram may follow the patterns of myocardial ischemia seen in coronary thrombosis and is likely to lead to a mistaken diagnosis unless some of the other main branches of the aorta are similarly affected in a way which reveals that the primary difficulty is in the aorta rather than in the coronary arteries. TESTS FOR SYPHILIS.-The Wassermann reaction and other serological tests for syphilis when positive likewise serve more often than not to confuse the diagnosis. This is especially true when the dissection results in the development of aortic insufficiency.9 When it can be ascertained to be the case, the sudden onset of the latter helps to distinguish between luetic aortitis and dissecting aneurysm involving the aortic ring. PROGNOSIS
The course of this disorder varies from sudden death at the onset to more or less asymptomatic survival for several years in a few instances. It is probable that, as in the case of coronary thrombosis, prognoses will become somewhat more favorable as diagnoses improve. It will always have to be regarded as a serious accident to the cardiovascular system. TREATMENT
The treatment consists in rest in bed during the acute stage, with whatever sedation proves necessary to keep the patient as comfortable as may be. Repeated doses of morphine are frequently indicated but the smallest amount should be used which will suffice to relieve the pain.
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Perhaps the most important feature of the treatment rests in making a diagnosis which will preclude surgical interference for various supposed colics or arterial emboli. PRESENTATION OF CASES
With these considerations in mind the seven cases found at autopsy at the University of Chicago Clinics during the first fifteen years of operation were reviewed. Only two of these cases were correctly diagnosed during life. In the presentation of these cases, special attention will be given to findings in the histories which might have led to a correct diagnosis in those instances in which it was missed. CASE I.-The patient was a white man seventy-three years old in April of 1929 when he was first seen. He had a history of herpes zoster involving the left leg in September, 1928, at which time diabetes was also diagnosed. He complained of residual pain in this leg. Nothing was found on examination germane to this discussion except a blood pressure of 170/90. Two years later he was seen again complaining of intermittent claudication and no pulse could be found in either dorsalis pedis or posterior tibial artery. Two months later he complained of mild pain in the arms and back.· Three months later (August 31, 1931) he entered the hospital complaining of substernal pain of eight hours' duration and radiating down both arms. The findings were essentially unchanged except for tne blood pressure, which was 150/98. Three days later a pericardial friction rub was heard and the blood pressure was 110/70. Electrocardiograms were typical of coronary thrombosis and this diagnosis was made. The patient died suddenly six days later. Autopsy revealed 270 cc. of blood in the partially obliterated pericardial sac. There was an occlusion of the circumflex branch of the left coronary artery and a myocardial infarct which had ruptured. An incidental finding was a very small (1 by 3 cm.) dissecting aneurysm 5 cm. above the bifurcation of the aorta. The material in this aneurysm included necrotic debris as well as discolored blood and it was presumed to be old.
Corml1ent.- The cause of death was properly diagnosed in this case but there was an additional finding: the small dissecting aneurysm near the end of the aorta, which appeared much older. Even if the assumption be made that it was somehow concerned in the production of his leg pains it is extremely doubtful that a correct diagnosis could have been made. There was no history
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of low back pain of any severity and there were ample reasons for leg pain in the shape of arteriosclerosis and a history of herpes zoster. CASE II.-This white man of sixty-eight had a history of anginal pain radiating to the right arm for one year before he was first seen on June 26, 1931. His heart was slightly enlarged and his blood pressure was 145/96. Electrocardiogram revealed what we would now call "left ventricular strain." Roentgenography and fluoroscopy showed a dilated, tortuous senile aorta with calcified plaques in the knob. There was some doubt as to whether the first portion of the aorta was sufficiently dilated to warrant the diagnosis of aneurysm, and the roentgenologist who first raised the question decided against it at a later visit. He had two attacks of precordial pain, dyspnea and cyanosis lasting for hours, one on July 25, 1931, and one September 15, 1933. These were diagnosed as coronary occlusions. After the last one he had sympoms of heart failure until his death March 19, 1934. Autopsy revealed a generalized arteriosclerosis with marked calcification and narrowing of both coronary arteries. There was disseminated and focal fibrous scarring of the myocardium with beginning aneurysmal dilatation of the apex of the left ventricle (probably small healed infarcts). There was general dilatation of the ascending aorta and medial necrosis and rupture in the arch with the formation of two small dissecting aneurysms (one 1.5 cm., the other 8 mm. in its longest diameter). These small aneurysms were filled with laminated organizing blood clots.
Comment.-Again the cause of death was properly diagnosed but the existence of incomplete rupture of the aorta with small dissecting aneurysms was unsuspected during life. It is possible that one or two of his attacks of anginal pain differed in character or radiation sufficiently to make the alert physician suspect some such episode but this does not seem at all likely. On a statistical basis multiple sites for the origin of variable coronary pain would be much more probable. CASE III.-The patient, a white man aged fifty-one years, was first seen August 26, 1932, complaining of dizziness, especially when stooping. His blood pressure ;was 188/128 and the aortic second sound was ringing although he was said to have had a normal blood pressure two years previously. Cardiac and renal functions were within normal limits at this time. He had no other symptoms until March 23, 1934, when he noticed an occasional desire to sit up in
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bed to breathe freely. By January of 1935 he had frank symptoms of myocardial insufficiency. He entered the hospital March 8, 1935, complaining of dyspnea, weakness, cough and frontal headaches. His blood pressure was 224/184 and the pulse rate was 120 per minute. The heart was only slightly enlarged to percussion and a systolic murmur was heard both at the apex and base. He was markedly orthopneic. There was a definite pulsation in the epigastrium synchronous with the heart beat. Kidney function was now reduced by the urea clearance test to about 50 per cent of normal. On his last day of life, March 15, 1935, he failed rapidly and the blood pressure gradually dropped to 92/70 just before death. The clinical diagnosis was malignant hypertension with myocardial and renal insufficiency. Autopsy re~ealed arteriolar nephrosclerosis with marked cardiac hypertrophy and marked atheromatosis of the large and medium sized arteries. There was an early bronchopneumonia. The abdominal aorta had more atheromatosis than the thoracic aorta and contianed an occasional fibrous patch. Microscopically there was one early thrombus in the media of the abdominal arota in an area representing the beginning formation of a dissecting aneurysm.
Commem.- The anaromic diagnosis confirmed the clinical diagnosis of malignant hypertension. Although the microscopic findings permitted the pathological diagnosis of early dissecting aneurysm the presumption is high that this lesion was terminal and asymptomatic and hence not capable of diagnosis during life. . CASE IV.-This patient was a forty-three-year-old white man who was first seen on July 2, 1935, complaining of "kidney trouble." Three years previously he had had swelling of the eyelids and ankles diagnosed nephritis elsewhere. For six months he had noted an increasing shortness of breath. Off and on during the three years he had had a pain in the hack of the neck, pounding in character and synchronous with the heart beat. Examination revealed a pale, dyspneic man whose heart was enlarged and whose blood pressure was 215/130. His hemoglobin was 50 per cent and his red blood count was 2,190,000. The urine showed albumin 4 plus, a few red blood cells and occasional hyaline and granular casts. Renal function was 10 per cent of normal. The patient was hospitalized on July 10, 1935, and improved slightly thereafter until the evening of July 17, when he suddenly developed an excruciating pain between his shoulder blades. Five minutes later the pain radiated to the precordium and left arm. He
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was more dyspneic and somewhat cyanotic. He was given % grain of morphine, repeated in twenty minutes, and two hours later % grain. His blood pressure at first was 254/148. The next day it was 224/132 at 8:00 A. M., 228/130 at 10:00 A. M., 226/128 at 12:00 M. and 228/126 at 5:00 P. M. During this day he received % grain of morphine and was drowsy and partially disoriented. Without further sedation he remained completely disoriented until July 23, although his blood pressure remained between 224 and 242 systolic and between 114 and 136 diastolic. On July 23 he complained of more pain in the chest and back and was given two doses of morphine, each % grain. The next day he developed a loud pericardial friction rub. The next day, July 25, 1935, his blood pressure dropped for the first time to 152/84 and he died at 3:50 P. M. The clinical diagnosis was chronic diffuse glomerulonephritis, renal and myocardial insufficiency, and dissecting aneurysm of the throacic aorta. Autopsy revealed chronic glomerulonephritis and hypertrophy of the left ventricle of the heart. There was a transverse rupture of the aorta at the arch with an organized peri-aortic hematoma and a dissecting aneurysm arising at the point of rupture and extending distally 2 cm. There was a uremic pericarditis.
Comment.-The correct ante-mortem diagnosis was made in this case in spite of a strong suspicion of a coronary thrombosis largely because the blood pressure failed to drop; the electrocardiogram was not characteristic of coronary occlusion and the pain started in the back between the shoulder blades. The diagnosis, made originally by an assistant resident, was the more commendable in the face of the facts that within five minutes the pain had largely shifted to the precordium and radiated down the left arm, a frank pericardial friction rub developed later and lastly, the terminal uremic disorientation made the symptomatology vague. CASE V.-This white man entered the hospital on July 6, 1936. That morning at 6:45 he was seized with a sharp, stabbing pain over the left cheek which radiated to the back of the neck and down the spine to about the 8th thoracic vertebra. The pain in the back persisted as the pain in the jaw subsided. Later in the day he developed "pin-pricks" in the right arm. There was no sternal or . precordial pain. He had no knowledge of pre-existing trouble. On examination little was found except a blood pressure of 176/120, a white blood count of 13,200 and sugar 2 plus in the urine. That evening he suddenly stopped talking in the middle of a sentence, became unconscious and his systolic blood pressure fell to 72. The
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next day his blood pressure was 110/98 and an electrocardiogram was not characteristic of coronary thrombosis. Chest roentgenograms taken on a "pneumonia bed" showed a widening of the mediastinal shadow, diagnosed as an aortic aneurysm by the roentgenologist. The blood pressure on the next day was 128/88 in the left arm and 130/90 in the right. He still had pain across the shoulders. He suddenly expIred at 4: 30 A. M. the next morning (July 9, 1936). The clinical diagnosis was dissecting aneurysm of the thoracic aorta. Autopsy revealed a dissecting aneurysm of the aorta with aortic medianecrosis, and rupture of the aorta at the ring with hemorrhage into the pericardial sac, periaortic tissue and both pleural cavities. There was mild coronary atherosclerosis.
Comment.-The correct clinical diagnosis was based upon the location and radiation of the pain (only in the back, never precordial), the lack of electrocardiographic change and the roentgenographic finding of widening of the aorta. The drop in blood pressure was misinterpreted as evidence of coronary thrombosis but this opinion did not prevail in the face of accumulating laboratory evidence to the contrary. CASE VI.-This patient, a white man aged sixty-eight years, entered the hospital on May 10, 1940. He had known of high blood pressure for six months. For four months he had had an increasing weakness, dyspnea and weight loss and had vomited for the first time the day before admission. On the day of admission he developed lower left chest pain of intense severity. On examination he appeared emaciated and sick. His heart was enlarged and there was a systolic apical murmur. His blood pressure was 220/148 and the heart rate was 112. One hour later there was a loud pericardial friction rub. Hemoglobin was 60 per cent, red blood count 2,880,000. The urine showed albumin 3 plus and a few hyaline casts. He was given morphine on three occasions during the first two days because of severe precardial pain and dyspnea. His blood pressure on the second day was 200/160 and on the third was 144/88. He became comatose and died on May 13, at 3: 15 A. M. The clinical diagnosis was hypertensive cardiovascular disease and coronary thrombosis. Autopsy revealed a chronic arteriolonephrosclerosis and chronic . primary hypertension with marked concentric hypertrophy of the heart, acute serofibrinous uremic pericarditis and marked atherosclerosis of the aorta and coronary arteries. An early dissecting aneurysm was found in a microscopic section of the first portion
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of the aorta. At this point there was a diffuse inflammation of the media characterized by the presence of polymorphonuclears and mononuclears as well as fibrinoid necrosis and a definite break in the intima and media.
Cormnent.-In retrospect it is probable that the patient's severe precordial pain was that of uremic pericarditis and that the microscopic tear in the aorta had nothing to do with it. The mistaken clinical diagnosis of coronary thrombosis might have been avoided, too, if serial electrocardiograms had been taken. This was not done because of overconfidence on the part of the clinician in his early diagnosis and because the patient was continuously in an oxygen tent. Both of these are inadequate reasons. The dissecting aneurysm was probably too small to permit of an ante-mortem diagnosis although not enough is yet known about the degree of pain such a lesion can produce. CASE VII.-This white man of fifty-two years entered the hospital on January 29, 1942, complaining of shortness of breath and edema of the ankles of seven months' duration. A physician who saw him before admission had found a blood pressure of 240 and had put him to bed for a time. His symptoms increased in severity and included a cough and some vertigo on admission here. He had had low back pain for an indefinite but "long period" of time which had become much worse during the month preceding his admission. This pain did not radiate but was at times "very severe." On examination he was a very obese, worried patient with some orthopnea. The heart was enlarged, there were systolic and diastolic murmurs at the base and the blood pressure was 256/110. Respirations were 30 per minute. There was a pitting edema of the ankles. Albumin and casts were found in the urine. He was ~eated for heart failure and lost 20 kg. in nineteen days. He was discharged subjectively improved with a blood pressure which averaged 190/115. The patient re-entered the hospital on April 27, 1942, complaining of the same symptoms, i.e., dyspnea and edema of the ankles and a cough. He had seen clotted blood in the urine on two or three occasions two weeks before this admission. He had also had frequent, severe aches in the right flank. His condition remained uncha-nged until May 4, 1942, when, at 3:00 A. M., he developed a pain "in the left soulder blade" and felt "different than he had ever felt." Morphine gave temporary relief but he was found dead in bed at 1:00 P. M. His blood pressure had dropped from 200/110 to 160/95 and then returned to '200/120 on this day. The clinical
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diagnosis was hypertensive cardiovascular disease with a terminal coronary occlusion. Autopsy revealed a large transverse laceration of the ascending aorta just above the valve and a dissecting aneurysm extending the entire length of the aorta, into both common iliac arteries and out along the right renal artery. There was a tear through the adventitia, of the ascending aorta with hemorrhagic infiltration of the mediastinal tissues and a massive, fatal hemopericardium (cardiac tamponade). Although there was marked aortic sclerosis, sections showed only a very mild medial degeneration. Embolic occlusion of a left renal branch and of a branch of the splenic artery had occurred. There was profound atrophy of the cerebral cortex.
Cornment.- The tenninal event in this patient's illness might have been suspected if more attention had been paid to the location of his pain, the recovery in his blood pressure and possibly to the gross hematuria occurring two weeks before death. The latter symptom, however, might well have been the result of the embolic occlusion of the renal artery found postmortem. His great obesity (he weighed 133.4 kg. [293 pounds]) and his clouded sensorium contributed to the difficulty. The one made for technically unsatisfactory chest roentgenograms, the other for doubt about the location, duration and severity of his low back, right flank and later, left scapular pain. SUMMARY AND CONCLUSIONS
Some helpful leads to the making of a correct ante-mortem diagnosis of dissecting aneurysm of the aorta have been gathered from the literature. These may be epitomized by saying: When severe pain, especially upper back pain, is accompanied by cerebral symptoms, a change in the blood pressure of one extremity only, hematuria, transient paralysis of the legs, no electrocardiographic changes, a widened aorta or a suddenly developing aortic insufficiency, dissecting aneurysm should be suspected. Seven cases found at autopsy have been reviewed. In four the diagnosis was not made and most probably could not have been made. In two the ante-mortem diagnosis was made correctly. In one the condition was not suspected when there were some hints of the type mentioned above which were overlooked.
J. L.:
BIBLIOGRAPHY
Dissecting Aneurysm. Am. Heart J., 24:69, 1942. 2. Cherry, Clifford B. and Cherry, Kathryn T.: Dissecting Aneurysm of the Aorta. IndUStrial Med., 10:525, 1941. 1. Mote, C. D. and Carr,
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3. Erdheim, J.: Medionecrosis Aonae Idiopathica. Virchow's Arch. f. path. anat., 273:454, 1929. 4. Gallavardin, L. and Gravier, L.: Incomplete Rupture of the Aorta Followed by Functional Aonic Insufficiency. Paris Med., 45:23, 1922. . 5. Peery, T. M.: Incomplete Rupture of the Aona. Arch. Int. Med., 70:689,
1942. 6. Crowell, P. D.: Dissecting Aneurysms of the Aorta. J.A.M.A., 77:2117, 1921.
7. Buckley, T. }.: Hematuria Associated with Dissecting Aneurysms of the Abdominal Aorta. J. Urol., 44:816, 1940. 8. Tuohy, E. L., Boman, P. G. and Berdez, G. L.: Spinal Cord Ischemia in Dissecting Aneurysm. Am. Heart J., 22:305, 1941. 9. Gouley, B. A. and Anderson, E.: Chronic Dissecting Aneurysm of the Aorta Simulating Syphilitic Cardiovascular Disease. Ann. Int. Med., 14:978, 1940.
PRECIPITATING FACTORS
It occurs much more frequently in men than in women and usually in patients with pre-existing hypertension. Syphilis of the aorta is not an important predisposing factor nor is external trauma as frequent a precipitating factor as was formerly thought. The role of unusual exertion in its onset is not yet a settled point. Cherry and Cherry2 believe that on a statistical ba~is exer• From the Department of Medicine, University of Chicago School of Medicine. t Professor of Medicine, University of Chicago School of Medicine. :t: No attempt is made to be all-inclusive in the appended bibliography. For an excellent historical account of our knowledge of this disease and a good bibliography the reader is referred to an article by Flaxman in the American Heart Journal, 24:654, 1942. . 112
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tion is a coincidental rather than a necessary precipitating factor. This, of course, has important medicolegal connotations. There are case histories available, however, which suggest strongly that, in the presence of a background for trouble, excessive exertion is dramatically related to the beginning of symptoms. ETIOLOGY AND PATHOLOGY
The pathogenesis probably includes two main modes of development. Erdheim's3 medial necrosis is the primary lesion in some cases and results in dissection by virtue of hematoma formation within the wall of the aorta brought about by rupture of the vasa vasorum. This subsequently may break through the intima in one or more places. Primary rupture of the intima and subsequent dissection of the media also occur in the absence of pre-existing medial necrosis. Such intimal tears may occur without dissection and have . been labeled incomplete rupture of the aorta by Gallavardin and Gravier4 and Peery.5 The latter states that this lesion is probably IIlore frequent than dissecting aneurysm although it has not so far been diagnosed ante mortem. Secondary pathologic changes serve to explain many of the mistakes in ante-mortem diagnoses, as was pointed out by Crowell. 6 The intimal tear, with or without medial necrosis, may occur at any point along the aorta but more often is found in the ascending aorta near the aortic ring and frequently in that portion of the wall within the reflected pericardial sac. The subsequent dissection may travel in either or both directions up and down the aorta as well as around it. Its encroachment on the branches of the aorta and on the aortic ring produces the varied symptomatology which at once makes its diagnosis possible in an increasing number of cases and serves to confuse it with the wide range of clinical entities cited above. It may, for example, result in a suddenly developing aortic insufficiency by one of three mechanisms described in the literature. It may result in the partial or complete occlusion of one or more coronary, subclavian, carotid, intercostal, renal, mesenteric or common ili3;c arteries. The vessel or vessels involved determine the signs and symptoms produced. Death may come suddenly when the dissecting aneurysm or the incomplete rupture of the aorta breaks through the adventitia. There are cases on record, however, in which survival of
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such an accident has occurred, at least for a few days. The rupture may occur into the pericardial sac with resulting cardiac tamponade or into the pleural space, the mediastinum, the abdominal cavity, the retroperitoneal tissues, or even into the gast:ro-intestinal tract and be accompanied by the vomiting of blood. DIAGNOSIS
SYMPToMs.-Although "silent" dissections of the wall of the aorta are thought to occur, by far the majority of those which result in survival are accompanied by pain. This pain is often excruciating, unrelieved by large doses of morphine. It frequently resembles the distress in the chest produced by coronary thrombosis but does not radiate to the arms characteristically. It does tend to radiate to the back between the scapulae and sometimes to the neck and head, lower back and legs. Occasionally it travels, hour by hour or day by day, down the back from the neck to the legs. It may be throbbing in character and intermittent, lasting a few hours at a time. Other symptoms, not invariably present, include dyspnea, vomiting, loss of consciousness, transient paralysis of the legs and in some instances those of heart failure. Rarely, hematuria has been prominent enough to suggest primary renal pathology.7 PHYSICAL FINDINGs.-On physical examination there may be little to find which differs from the pre-existing record when such is available. The blood pressure, usually elevated previously, does not drop unless the patient develops the signs and symptoms of shock or unless the orifice or first portion of the artery in the extremity tested has been involved in the dissection. In the latter instance, the drop in blood pressure in one or two extremities and not in the others, in the presence of chest and back pain, points the way to a correct diagnosis. The sudden development of the diastolic murmur of aortic insufficiency accompanied by the increased pulse pressure and other peripheral manfestations of this lesion within a day or two after the onset of chest and back pain is another clue strongly suggestive of the true nature of the pathology present when it occurs. Transient changes in the strength and reflexes of one or both lower extremities when other symptoms of a dissecting aneurysm exist help to make the diagnosis definite. s
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In those instances in which the patient lives for months or years after the onset, there may be remarkably little to show for it on physical examination or the signs of gradually developing heart failure may supervene. X-RAY STUDy.-Among the laboratory procedures, roentgenography and fluoroscopy of the chest are the most helpful. A generalized widening of the aorta, especially in oblique views, is the characteristic finding. Occasionally this may include a widening of the vessels of the upper mediastinum. ELECTROCARDIOGRAPHY.-The electrocardiogram usually does not change materially unless the coronary orifices are involved in the dissection. This negative finding is of some help in the differential diagnosis. In the event the coronaries are obstructed, the electrocardiogram may follow the patterns of myocardial ischemia seen in coronary thrombosis and is likely to lead to a mistaken diagnosis unless some of the other main branches of the aorta are similarly affected in a way which reveals that the primary difficulty is in the aorta rather than in the coronary arteries. TESTS FOR SYPHILIS.-The Wassermann reaction and other serological tests for syphilis when positive likewise serve more often than not to confuse the diagnosis. This is especially true when the dissection results in the development of aortic insufficiency.9 When it can be ascertained to be the case, the sudden onset of the latter helps to distinguish between luetic aortitis and dissecting aneurysm involving the aortic ring. PROGNOSIS
The course of this disorder varies from sudden death at the onset to more or less asymptomatic survival for several years in a few instances. It is probable that, as in the case of coronary thrombosis, prognoses will become somewhat more favorable as diagnoses improve. It will always have to be regarded as a serious accident to the cardiovascular system. TREATMENT
The treatment consists in rest in bed during the acute stage, with whatever sedation proves necessary to keep the patient as comfortable as may be. Repeated doses of morphine are frequently indicated but the smallest amount should be used which will suffice to relieve the pain.
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Perhaps the most important feature of the treatment rests in making a diagnosis which will preclude surgical interference for various supposed colics or arterial emboli. PRESENTATION OF CASES
With these considerations in mind the seven cases found at autopsy at the University of Chicago Clinics during the first fifteen years of operation were reviewed. Only two of these cases were correctly diagnosed during life. In the presentation of these cases, special attention will be given to findings in the histories which might have led to a correct diagnosis in those instances in which it was missed. CASE I.-The patient was a white man seventy-three years old in April of 1929 when he was first seen. He had a history of herpes zoster involving the left leg in September, 1928, at which time diabetes was also diagnosed. He complained of residual pain in this leg. Nothing was found on examination germane to this discussion except a blood pressure of 170/90. Two years later he was seen again complaining of intermittent claudication and no pulse could be found in either dorsalis pedis or posterior tibial artery. Two months later he complained of mild pain in the arms and back.· Three months later (August 31, 1931) he entered the hospital complaining of substernal pain of eight hours' duration and radiating down both arms. The findings were essentially unchanged except for tne blood pressure, which was 150/98. Three days later a pericardial friction rub was heard and the blood pressure was 110/70. Electrocardiograms were typical of coronary thrombosis and this diagnosis was made. The patient died suddenly six days later. Autopsy revealed 270 cc. of blood in the partially obliterated pericardial sac. There was an occlusion of the circumflex branch of the left coronary artery and a myocardial infarct which had ruptured. An incidental finding was a very small (1 by 3 cm.) dissecting aneurysm 5 cm. above the bifurcation of the aorta. The material in this aneurysm included necrotic debris as well as discolored blood and it was presumed to be old.
Corml1ent.- The cause of death was properly diagnosed in this case but there was an additional finding: the small dissecting aneurysm near the end of the aorta, which appeared much older. Even if the assumption be made that it was somehow concerned in the production of his leg pains it is extremely doubtful that a correct diagnosis could have been made. There was no history
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of low back pain of any severity and there were ample reasons for leg pain in the shape of arteriosclerosis and a history of herpes zoster. CASE II.-This white man of sixty-eight had a history of anginal pain radiating to the right arm for one year before he was first seen on June 26, 1931. His heart was slightly enlarged and his blood pressure was 145/96. Electrocardiogram revealed what we would now call "left ventricular strain." Roentgenography and fluoroscopy showed a dilated, tortuous senile aorta with calcified plaques in the knob. There was some doubt as to whether the first portion of the aorta was sufficiently dilated to warrant the diagnosis of aneurysm, and the roentgenologist who first raised the question decided against it at a later visit. He had two attacks of precordial pain, dyspnea and cyanosis lasting for hours, one on July 25, 1931, and one September 15, 1933. These were diagnosed as coronary occlusions. After the last one he had sympoms of heart failure until his death March 19, 1934. Autopsy revealed a generalized arteriosclerosis with marked calcification and narrowing of both coronary arteries. There was disseminated and focal fibrous scarring of the myocardium with beginning aneurysmal dilatation of the apex of the left ventricle (probably small healed infarcts). There was general dilatation of the ascending aorta and medial necrosis and rupture in the arch with the formation of two small dissecting aneurysms (one 1.5 cm., the other 8 mm. in its longest diameter). These small aneurysms were filled with laminated organizing blood clots.
Comment.-Again the cause of death was properly diagnosed but the existence of incomplete rupture of the aorta with small dissecting aneurysms was unsuspected during life. It is possible that one or two of his attacks of anginal pain differed in character or radiation sufficiently to make the alert physician suspect some such episode but this does not seem at all likely. On a statistical basis multiple sites for the origin of variable coronary pain would be much more probable. CASE III.-The patient, a white man aged fifty-one years, was first seen August 26, 1932, complaining of dizziness, especially when stooping. His blood pressure ;was 188/128 and the aortic second sound was ringing although he was said to have had a normal blood pressure two years previously. Cardiac and renal functions were within normal limits at this time. He had no other symptoms until March 23, 1934, when he noticed an occasional desire to sit up in
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bed to breathe freely. By January of 1935 he had frank symptoms of myocardial insufficiency. He entered the hospital March 8, 1935, complaining of dyspnea, weakness, cough and frontal headaches. His blood pressure was 224/184 and the pulse rate was 120 per minute. The heart was only slightly enlarged to percussion and a systolic murmur was heard both at the apex and base. He was markedly orthopneic. There was a definite pulsation in the epigastrium synchronous with the heart beat. Kidney function was now reduced by the urea clearance test to about 50 per cent of normal. On his last day of life, March 15, 1935, he failed rapidly and the blood pressure gradually dropped to 92/70 just before death. The clinical diagnosis was malignant hypertension with myocardial and renal insufficiency. Autopsy re~ealed arteriolar nephrosclerosis with marked cardiac hypertrophy and marked atheromatosis of the large and medium sized arteries. There was an early bronchopneumonia. The abdominal aorta had more atheromatosis than the thoracic aorta and contianed an occasional fibrous patch. Microscopically there was one early thrombus in the media of the abdominal arota in an area representing the beginning formation of a dissecting aneurysm.
Commem.- The anaromic diagnosis confirmed the clinical diagnosis of malignant hypertension. Although the microscopic findings permitted the pathological diagnosis of early dissecting aneurysm the presumption is high that this lesion was terminal and asymptomatic and hence not capable of diagnosis during life. . CASE IV.-This patient was a forty-three-year-old white man who was first seen on July 2, 1935, complaining of "kidney trouble." Three years previously he had had swelling of the eyelids and ankles diagnosed nephritis elsewhere. For six months he had noted an increasing shortness of breath. Off and on during the three years he had had a pain in the hack of the neck, pounding in character and synchronous with the heart beat. Examination revealed a pale, dyspneic man whose heart was enlarged and whose blood pressure was 215/130. His hemoglobin was 50 per cent and his red blood count was 2,190,000. The urine showed albumin 4 plus, a few red blood cells and occasional hyaline and granular casts. Renal function was 10 per cent of normal. The patient was hospitalized on July 10, 1935, and improved slightly thereafter until the evening of July 17, when he suddenly developed an excruciating pain between his shoulder blades. Five minutes later the pain radiated to the precordium and left arm. He
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was more dyspneic and somewhat cyanotic. He was given % grain of morphine, repeated in twenty minutes, and two hours later % grain. His blood pressure at first was 254/148. The next day it was 224/132 at 8:00 A. M., 228/130 at 10:00 A. M., 226/128 at 12:00 M. and 228/126 at 5:00 P. M. During this day he received % grain of morphine and was drowsy and partially disoriented. Without further sedation he remained completely disoriented until July 23, although his blood pressure remained between 224 and 242 systolic and between 114 and 136 diastolic. On July 23 he complained of more pain in the chest and back and was given two doses of morphine, each % grain. The next day he developed a loud pericardial friction rub. The next day, July 25, 1935, his blood pressure dropped for the first time to 152/84 and he died at 3:50 P. M. The clinical diagnosis was chronic diffuse glomerulonephritis, renal and myocardial insufficiency, and dissecting aneurysm of the throacic aorta. Autopsy revealed chronic glomerulonephritis and hypertrophy of the left ventricle of the heart. There was a transverse rupture of the aorta at the arch with an organized peri-aortic hematoma and a dissecting aneurysm arising at the point of rupture and extending distally 2 cm. There was a uremic pericarditis.
Comment.-The correct ante-mortem diagnosis was made in this case in spite of a strong suspicion of a coronary thrombosis largely because the blood pressure failed to drop; the electrocardiogram was not characteristic of coronary occlusion and the pain started in the back between the shoulder blades. The diagnosis, made originally by an assistant resident, was the more commendable in the face of the facts that within five minutes the pain had largely shifted to the precordium and radiated down the left arm, a frank pericardial friction rub developed later and lastly, the terminal uremic disorientation made the symptomatology vague. CASE V.-This white man entered the hospital on July 6, 1936. That morning at 6:45 he was seized with a sharp, stabbing pain over the left cheek which radiated to the back of the neck and down the spine to about the 8th thoracic vertebra. The pain in the back persisted as the pain in the jaw subsided. Later in the day he developed "pin-pricks" in the right arm. There was no sternal or . precordial pain. He had no knowledge of pre-existing trouble. On examination little was found except a blood pressure of 176/120, a white blood count of 13,200 and sugar 2 plus in the urine. That evening he suddenly stopped talking in the middle of a sentence, became unconscious and his systolic blood pressure fell to 72. The
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next day his blood pressure was 110/98 and an electrocardiogram was not characteristic of coronary thrombosis. Chest roentgenograms taken on a "pneumonia bed" showed a widening of the mediastinal shadow, diagnosed as an aortic aneurysm by the roentgenologist. The blood pressure on the next day was 128/88 in the left arm and 130/90 in the right. He still had pain across the shoulders. He suddenly expIred at 4: 30 A. M. the next morning (July 9, 1936). The clinical diagnosis was dissecting aneurysm of the thoracic aorta. Autopsy revealed a dissecting aneurysm of the aorta with aortic medianecrosis, and rupture of the aorta at the ring with hemorrhage into the pericardial sac, periaortic tissue and both pleural cavities. There was mild coronary atherosclerosis.
Comment.-The correct clinical diagnosis was based upon the location and radiation of the pain (only in the back, never precordial), the lack of electrocardiographic change and the roentgenographic finding of widening of the aorta. The drop in blood pressure was misinterpreted as evidence of coronary thrombosis but this opinion did not prevail in the face of accumulating laboratory evidence to the contrary. CASE VI.-This patient, a white man aged sixty-eight years, entered the hospital on May 10, 1940. He had known of high blood pressure for six months. For four months he had had an increasing weakness, dyspnea and weight loss and had vomited for the first time the day before admission. On the day of admission he developed lower left chest pain of intense severity. On examination he appeared emaciated and sick. His heart was enlarged and there was a systolic apical murmur. His blood pressure was 220/148 and the heart rate was 112. One hour later there was a loud pericardial friction rub. Hemoglobin was 60 per cent, red blood count 2,880,000. The urine showed albumin 3 plus and a few hyaline casts. He was given morphine on three occasions during the first two days because of severe precardial pain and dyspnea. His blood pressure on the second day was 200/160 and on the third was 144/88. He became comatose and died on May 13, at 3: 15 A. M. The clinical diagnosis was hypertensive cardiovascular disease and coronary thrombosis. Autopsy revealed a chronic arteriolonephrosclerosis and chronic . primary hypertension with marked concentric hypertrophy of the heart, acute serofibrinous uremic pericarditis and marked atherosclerosis of the aorta and coronary arteries. An early dissecting aneurysm was found in a microscopic section of the first portion
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of the aorta. At this point there was a diffuse inflammation of the media characterized by the presence of polymorphonuclears and mononuclears as well as fibrinoid necrosis and a definite break in the intima and media.
Cormnent.-In retrospect it is probable that the patient's severe precordial pain was that of uremic pericarditis and that the microscopic tear in the aorta had nothing to do with it. The mistaken clinical diagnosis of coronary thrombosis might have been avoided, too, if serial electrocardiograms had been taken. This was not done because of overconfidence on the part of the clinician in his early diagnosis and because the patient was continuously in an oxygen tent. Both of these are inadequate reasons. The dissecting aneurysm was probably too small to permit of an ante-mortem diagnosis although not enough is yet known about the degree of pain such a lesion can produce. CASE VII.-This white man of fifty-two years entered the hospital on January 29, 1942, complaining of shortness of breath and edema of the ankles of seven months' duration. A physician who saw him before admission had found a blood pressure of 240 and had put him to bed for a time. His symptoms increased in severity and included a cough and some vertigo on admission here. He had had low back pain for an indefinite but "long period" of time which had become much worse during the month preceding his admission. This pain did not radiate but was at times "very severe." On examination he was a very obese, worried patient with some orthopnea. The heart was enlarged, there were systolic and diastolic murmurs at the base and the blood pressure was 256/110. Respirations were 30 per minute. There was a pitting edema of the ankles. Albumin and casts were found in the urine. He was ~eated for heart failure and lost 20 kg. in nineteen days. He was discharged subjectively improved with a blood pressure which averaged 190/115. The patient re-entered the hospital on April 27, 1942, complaining of the same symptoms, i.e., dyspnea and edema of the ankles and a cough. He had seen clotted blood in the urine on two or three occasions two weeks before this admission. He had also had frequent, severe aches in the right flank. His condition remained uncha-nged until May 4, 1942, when, at 3:00 A. M., he developed a pain "in the left soulder blade" and felt "different than he had ever felt." Morphine gave temporary relief but he was found dead in bed at 1:00 P. M. His blood pressure had dropped from 200/110 to 160/95 and then returned to '200/120 on this day. The clinical
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diagnosis was hypertensive cardiovascular disease with a terminal coronary occlusion. Autopsy revealed a large transverse laceration of the ascending aorta just above the valve and a dissecting aneurysm extending the entire length of the aorta, into both common iliac arteries and out along the right renal artery. There was a tear through the adventitia, of the ascending aorta with hemorrhagic infiltration of the mediastinal tissues and a massive, fatal hemopericardium (cardiac tamponade). Although there was marked aortic sclerosis, sections showed only a very mild medial degeneration. Embolic occlusion of a left renal branch and of a branch of the splenic artery had occurred. There was profound atrophy of the cerebral cortex.
Cornment.- The tenninal event in this patient's illness might have been suspected if more attention had been paid to the location of his pain, the recovery in his blood pressure and possibly to the gross hematuria occurring two weeks before death. The latter symptom, however, might well have been the result of the embolic occlusion of the renal artery found postmortem. His great obesity (he weighed 133.4 kg. [293 pounds]) and his clouded sensorium contributed to the difficulty. The one made for technically unsatisfactory chest roentgenograms, the other for doubt about the location, duration and severity of his low back, right flank and later, left scapular pain. SUMMARY AND CONCLUSIONS
Some helpful leads to the making of a correct ante-mortem diagnosis of dissecting aneurysm of the aorta have been gathered from the literature. These may be epitomized by saying: When severe pain, especially upper back pain, is accompanied by cerebral symptoms, a change in the blood pressure of one extremity only, hematuria, transient paralysis of the legs, no electrocardiographic changes, a widened aorta or a suddenly developing aortic insufficiency, dissecting aneurysm should be suspected. Seven cases found at autopsy have been reviewed. In four the diagnosis was not made and most probably could not have been made. In two the ante-mortem diagnosis was made correctly. In one the condition was not suspected when there were some hints of the type mentioned above which were overlooked.
J. L.:
BIBLIOGRAPHY
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