Herrman L. Blumgart

Experimental studies on the effect of temporary occlusion of coronary arteries

Abstract 1. 1. Experiments were performed on thirty-nine dogs to learn whether temporary occlusion of a coronary artery would produce myocardial infarction and persistent electrocardiographic changes characteristic of myocardial ischemia. 2. 2. In twelve of eighteen animals which were allowed to survive four or more days, electrocardiographic changes typical of myocardial ischemia, and of a character not observed in control experiments, were found during the first few days to weeks after occlusion of a coronary artery for five to forty-five minutes. The type, anterior or posterior, of these electrocardiographic changes varied according to whether the anterior descending or left circumflex artery was temporarily occluded. 3. 3. Eight animals died of ventricular fibrillation during the first five minutes of occlusion of the artery, or on re-establishment of the circulation after occlusions lasting fifteen to thirty minutes. 4. 4. No gross evidences of myocardial infarction were found in the seven animals which lived for four to forty days after occlusion of a coronary artery had been maintained for five to twenty minutes. 5. 5. There were gross evidences, proved subsequently by microscopic examination, of infarction in eight of eleven experiments in which occlusion of a coronary artery was maintained for twenty-five to forty-five minutes. 6. 6. In the hearts which showed infarction, the extent of the infarct was roughly in direct proportion to the duration of the arterial occlusion; the infarcted area in several of the hearts in which an artery had been occluded for forty to forty-five minutes was as large as that which occurs after permanent and complete occlusion of the artery. 7. 7. These observations afford evidence that temporary ischemia may cause irreversible myocardial changes, and, if the ischemia be of sufficient duration, may cause myocardial infarction of the same character and degree as that which occurs after permanent and complete occlusion of an artery. 8. 8. The electrocardiographic and myocardial observations on certain patients with coronary artery disease are discussed with reference to the information gained in this study.

The Experimental Production of Intercoronary Arterial Anastomoses and their Functional Significance

Animal experiments were done to learn the degree of coronary narrowing required to produce the larger intercoronary collateral channels, their speed of development, and the degree of protection afforded the myocardium. Twelve or more days of 75 per cent narrowing were required to produce sufficiently rich anastomotic communications to protect the myocardium from damage, and to permit survival after superimposed acute complete occlusion. The physiologic and pathologic significance of the intercoronary collateral communications and the clinical implications in coronary artery disease are discussed.

Angina pectoris: A clinical and pathologic correlation

Abstract 1.1. A clinico-pathologic study of angina pectoris was carried out in a group of 848 cases in which the coronary arteries were injected and dissected by the Schlesinger technic. The group consisted of 177 patients with angina pectoris of one months duration or longer and 671 control patients without cardiac pain. 2.2. Not a single patient with angina pectoris in the entire series was found to be free of heart disease. All anginal patients had either coronary, valvular or hypertensive heart disease; 90 per cent of them had coronary narrowing or occlusion. 3.3. To clarify the relative importance of various types of heart disease in the production of angina pectoris, the incidence of angina among patients with a single form of heart disease was determined. Angina was found in 52 per cent of patients with coronary occlusion, in 16 per cent of those with valvular lesions, in 5 per cent of those with coronary narrowing and in 3 per cent of those with hypertension. 4.4. There was a clear positive correlation between the degree of coronary obstruction and the incidence of angina pectoris; among patients with occlusions of three main coronary arteries the incidence of angina pectoris was 85 per cent. 5.5. The serious prognostic import of angina pectoris in this series is evident from the mortality figures. One-third of the patients were dead within one year after the onset of angina, half were dead within two years, three-quarters were dead within five years and nine-tenths within ten years. The average duration of angina pectoris differed according to the underlying etiology: it was shorter in valvular and longer in coronary heart disease. 6.6. Congestive failure was of more serious prognostic importance than angina pectoris in coronary disease and less serious in valvular disease. 7.7. An intercurrent episode of myocardial infarction did not shorten the prognosis of a patient with angina pectoris. 8.8. The underlying mechanism of angina pectoris appears to be a relative disproportion between the requirements of the heart for blood and the supply furnished by the coronary arteries; this disproportion results in paroxysmal relative ischemia. In coronary artery disease, angina pectoris, myocardial fibrosis and intercoronary anastomoses all result from myocardial ischemia; the first is a clinical expression, the second a pathologic end result and the third a compensatory response to ischemia.

Hypothyroidism Produced by Radioactive Iodine (I131) in the Treatment of Euthyroid Patients with Angina Pectoris and Congestive Heart Failure Early Results in Various Types of Cardiovascular Diseases and Associated Pathologic States

Hypothyroidism, induced by I131 to lessen the work of the heart, is proposed as a means of treating certain patients with angina pectoris and congestive failure who are refractory to the standard medical measures. Eighteen such patients have been treated. The period of follow-up averages thirteen months. Eight of the 13 patients with angina pectoris and 3 of 5 patients with congestive failure showed worthwhile improvement. In 6 of the 18 patients, the improvement was striking. Tentative criteria for the selection of patients, their pre- and post-treatment management, and detailed descriptions of the results are presented.

Location of Coronary Arterial Occlusions and Their Relation to the Arterial Pattern

The present study shows that the coronary artery pattern is not related to the prognosis after infarction nor can it be correlated with the incidence of occlusion or with the severity of atherosclerosis. This analysis re-emphasizes the severity of the occlusive process in patients with angina pectoris and, conversely, the relatively large percentage of patients having coronary occlusion who had either congestive heart failure or who were asymptomatic.The proper selection of patients for coronary artery surgery requires accurate angiography. The occurrence of multiple occlusions in a large number of cases points to certain difficulties in the interpretation of the coronary angiogram and also indicates the extremely limited role endarterectomy may be expected to play in the therapy of angina pectoris. Until such a time as the operative mortality and secondary failure rate, due to restenosis, can be reduced through new surgical technics, coronary endarterectomy should be considered an experimental procedure to be investigated vigorously in the laboratory but not to be applied for therapeutic purposes in man.

The effect of dicumarol on the heart in experimental acute coronary occlusion

Abstract 1. 1. In thirty-one dogs, the left anterior descending coronary artery or a major branch was ligated. The effect of the oral administration of Dicumarol on the myocardium and coronary arteries was studied in fourteen animals. In three dogs, heparin was administered several hours postoperatively until the effect of Dicumarol was apparent. Fifteen dogs served as a control group. 2. 2. The incidence and magnitude of hemorrhagic extravasations on the endocardium and pericardium were the same in the treated and untreated groups. 3. 3. The incidence and magnitude of miliary hemorrhages on microscopic examination of the heart muscle were similar in the dicumarolized and control animals. 4. 4. In a small group of dogs in which sufficient Dicumarol was administered to elevate the prothrombin time to levels as high as 132 seconds, no increase in the hemorrhagic phenomena was observed in the myocardium. 5. 5. The size of the infarcts in the Dicumarol-treated and untreated animals showed no significant differences. The size of the infarcts was that which could be anticipated on the basis of the artery occluded. 6. 6. There were no apparent differences in the healing or reparative processes in the hearts of the Dicumarol-treated and the control animals. 7. 7. Thrombotic occlusions of the smaller arteries were found within the infarcted area in dogs receiving Dicumarol approximately as often as in the untreated group. No thrombi were found in the region of the tie below the point of occlusion. In one instance, an untreated animal, a thrombus was found in the region of the tie above the point of occlusion. 8. 8. No mural thrombi were found in the auricles or ventricles in the treated or in the untreated animals. 9. 9. The development of collateral anastomotic channels between the coronary arteries was the same in both groups. On or about the fourth day, unmistakable evidences of collateral vessels between the left anterior descending branch distal to the tie and the circumflex branch of the left coronary artery were observed. On and after the sixth day of survival, the magnitude of these anastomotic vessels was markedly increased.

Pathologic Physiology of Angina Pectoris and Acute Myocardial Infarction

Some of the unique physiologic characteristics of the coronary circulation have been pointed out. In the normal heart, the coronary arteries are functionally end arteries. Watery injections, however, reveal anatomic fine anastomotic communications between the coronary arteries measuring less than 40 &mgr;. But they are of limited functional significance in obviating the untoward effects of sudden coronary narrowing or occlusion. Complete occlusion or considerable narrowing of one or more coronary arteries may exist without giving rise to any clinical signs or symptoms and without having produced myocardial damage. The apparent inconsistency between the presence of long-standing obstructive arterial lesions and the absence of significant pathologic or clinical evidence of myocardial damage is dispelled by the demonstration of a collateral circulation which serves as a bypass in relation to the obstruction in each of these hearts. The pathologic and physiologic substrates of angina pectoris, coronary failure, and acute myocardial infarction have been discussed.

The Lewis A. Conner Memorial Lecture

The physiologic, pathologic, and clinical interrelationships between the thyroid and the cardiovascular system are discussed. The therapeutic effects of hypothyroidism induced by I131 to lessen the work of the heart are described in 39 euthyroid patients with intractable advanced angina pectoris or congestive failure. Only patients were treated who were seriously incapacitated despite all conventional forms of therapy for many months or years. The results of two confirmatory series of cases similarly treated by others are reviewed.

Radioactive Iodine Treatment of Angina Pectoris and Congestive Heart Failure

This 66-year-old man with angina pectoris for 17 years before treatment, incapacitated for several years despite long periods of rest and other therapy, showed significant improvement 2 months after I131 therapy and for the past 18 months he has been maintained in the hypometabolic state, free of pain despite greatly increased activity.

The circulatory dynamics in tricuspid stenosis

Abstract The cardiovascular dynamics in a patient with tricuspid stenosis and insufficiency were investigated. The clinical diagnosis was made on the basis of the marked generalized venous engorgement, cyanosis, slight jaundice, pulsation of the veins and of the enlarged liver, and the presence of typical murmurs to the right of the xiphoid. A high venous pressure was noted in both the arm and leg veins; this observation corroborated the clinical finding of marked generalized venous engorgement. Elevation of the venous pressure is commonly regarded as the chief, if not the only, cause of cardiac edema. It is striking that no edema was present in this case. Of significance in this connection are the observations on the cardiac output, arteriovenous oxygen difference, and venous oxygen content and saturation. All were essentially normal, i.e., no anoxemia was present. The concentration of plasma protein was normal. These findings strongly suggest that factors other than the venous pressure are likewise of importance in the formation of cardiac edema. The studies on orthopnea in this patient support the theory that elevation of the venous pressure may be a significant factor in the genesis of orthopnea.The cardiovascular dynamics in a patient with tricuspid stenosis and insufficiency were investigated. The clinical diagnosis was made on the basis of the marked generalized venous engorgement, cyanosis, slight jaundice, pulsation of the veins and of the enlarged liver, and the presence of typical murmurs to the right of the xiphoid. A high venous pressure was noted in both the arm and leg veins; this observation corroborated the clinical finding of marked generalized venous engorgement. Elevation of the venous pressure is commonly regarded as the chief, if not the only, cause of cardiac edema. It is striking that no edema was present in this case. Of significance in this connection are the observations on the cardiac output, arteriovenous oxygen difference, and venous oxygen content and saturation. All were essentially normal, i.e., no anoxemia was present. The concentration of plasma protein was normal. These findings strongly suggest that factors other than the venous pressure are likewise of importance in the formation of cardiac edema. The studies on orthopnea in this patient support the theory that elevation of the venous pressure may be a significant factor in the genesis of orthopnea.