Donald G. Kassebaum

Pulmonary edema in coronary-artery disease without cardiomegaly. Paradox of the stiff heart.

ACUTE pulmonary edema usually is accompanied by cardiomegaly unless it is of noncardiac origin, or occurs in special cases of heart failure1 , 2 such as restrictive cardiomyopathy, mitral stenosis,...

Myocardial Hypoxia as the Basis for Angina Pectoris in a Patient with Normal Coronary Arteriograms

Abstract Although coronary arteriograms of a 48-year-old woman with exertional chest pain typical of angina pectoris and an abnormal exercise electrocardiogram were normal, myocardial hypoxia and anaerobic metabolism were demonstrated during induced tachycardia and are proposed as the basis of the angina pectoris. A cause of impaired myocardial oxygen metabolism other than obstructive disease of visible coronary arteries is suggested.

A comparison of hypoxemia and exercise electrocardiography in coronary artery disease: Diagnostic precision of the methods correlated with coronary angiography☆

Exercise and hypoxemia electrocardiography were done when the resting ECG was normal in 35 normal control subjects, in 25 with atypical chest pain not believed clinically to be angina pectoris, and in 43 patients with typical angina pectoris. Coronary arteriography was done in all 68 patients of the latter two groups. Two of the patients believed clinically to have no coronary disease had minimal angiographic evidence of arteriosclerosis. Six of the patients with typical symptoms of angina pectoris had normal coronary arteriography. In both the normal controls and those with angiographically normal vessels, about 10 per cent had “ischemic” ST depression (segment flat for ≥ 0.08 second) ≥ 0.5 mm. with hypoxemia. Depression of the R-ST junction alone was rare. In the 39 patients with coronary disease, hypoxemia produced “ischemic” ST depression ≥ 0.5 mm. in 67 per cent, J depression in 7 per cent, and no ST change in 26 per cent. The in-exercise ECG showed J depression averaging 1.0 mm. in 83 per cent of the controls and in 48 per cent of the angiographically normal patients. “Ischemic” ST depression ≥ 1.0 mm. occurred in only 5 per cent. In the 39 patients with coronary disease, exercise produced segmental ST depression < 1.0 mm. in 8 per cent, “ischemic” depression ≥ 1.0 mm. in 46 per cent, J depression in 36 per cent, and no ST change in 10 per cent. The QXQT and QT ratios were “abnormal” in the majority of cases with coronary artery disease, but also in half of the normals, and were unreliable in the evaluation of ST depression. This study has shown the relatively high incidence of J depression with exercise in both normal subjects and those with coronary disease. While false-positive tests could be held to a minimum by accepting only “ischemic” ST depression ≥ 1.0 mm. as the criterion of a positive test, this finding occurred with exercise in less than half of the patients with documented coronary disease. Hypoxemia testing produced “ischemic” ST-segment depression ≥ 0.5 mm. in 23 of the patients with documented coronary disease. Although this test was less sensitive than exercise, the ST alterations which occurred were more discriminating.

Clinically suspect ischemic heart disease not corroborated by demonstrable coronary artery disease. Physiologic investigations and clinical course.

Abstract In 11 patients with angina pectoris and abnormal stress electrocardiograms, no narrowing or obstruction of coronary vessels was visible by selective cut film and coronary cinearteriography. One patient showed chemical evidence of myocardial hypoxia despite normal arteriograms. Similar evidence of impaired myocardial oxygen supply was absent in the remaining 10 patients. We found no abnormality in hemoglobin O 2 affinity which might jeopardize myocardial O 2 supply. The clinical course of these patients, including that during a 1 to 2 year followup period, has not been complicated by myocardial infarction or cardiac failure. In 5 symptoms have decreased.

Electrophysiological Effects of Isoproterenol on Purkinje Fibers of the Heart

The effects of isoproterenol on resting and action potentials, automaticity and conduction velocity in isolated Purkinje fibers of sheep hearts were studied with microelectrode recording techniques. In quiescent Purkinje fibers, local application of isoproterenol to the site of microelectrode recording caused depolarization to a potential level from which repetitive discharge occurred. During the acceleration in beat frequency, the threshold and maximum diastolic potentials increased. When isoproterenol was applied to the pacemaker of beating fibers, the steepness of the pacemaker potential increased and the rate accelerated. Threshold and maximum diastolic potentials were affected variably in the beating preparation. Isoproterenol did not change conduction velocity in isolated, stimulated Purkinje fibers. The electrophysiological effects of isoproterenol resemble those described previously for epinephrine. The observations do not permit definition of the mechanism of action.

Stress electrocardiography in the evaluation of aortocoronary bypass surgery

Abstract Forty-five patients having saphenous vein aortocoronary bypass surgery were studied prospectively by pre- and post-operative hypoxemia and graded exercise electrocardiography. The stress electrocardiographic results were correlated with the degree of symptomatic relief and the angiographic evidence of graft patency and the distribution and evolution of coronary occlusive disease. Forty-one of the total group of 45 patients (91 per cent) and 32 of 34 (94 per cent) with one or more documented open grafts had excellent or good symptomatic improvement. Incongruously, five of seven patients with closed grafts also had significant clinical improvement. Functional improvement was documented in 53 per cent of patients after aortocoronary bypass surgery, in terms of postoperative reversal of the preoperatively positive stress ECG or persistance of a negative stress ECG, together with the achievement of significantly greater mean maximum exercise and heart rate. All of these patients had one or more patent saphenous vein bypass grafts. Forty-seven per cent of the patients failed to display objective evidence of improvement: post-operatively the stress ECG either remained positive, or became so, and, collectively, the group was unable to significantly increase the mean maximum exercise level or heart rate, in comparison to that achieved before surgery. Only 65 per cent of these subjects had one or more patent bypass grafts. Stress electrocardiography and quantitation of the maximum work and heart rate achieved by exercise provide accurate assessments of the relief of myocardial ischemia produced by myocardial revascularization. In this study, when the post-operative stress ECG was negative and the patient was able to achieve significantly greater exercise and heart rate, the probability of patency of one or more bypass grafts was virtually certain. On the other hand, when the postoperative stress ECG was positive and little or no increase in exercise and heart rate was possible, there was high probability of graft occlusion or significant residual coronary disease.

Observations on the Occurrence of Right Bundle-Branch Block Following Open Repair of Ventricular Septal Defects

The occurrence of right bundle-branch block and varying degrees of altered ventricular conduction in a group of cases of ventricular septal defects repaired by direct closure is presented. The development of abnormal conductionis correlated with the location of the ventricular septal defects and the relationship of the conduction tissue. The etiologic role of operative trauma to the conduction system is reviewed, and the influence of ventriculotomy alone is discounted.

Stress Electrocardiography in the Evaluation of Surgical Revascularization of the Heart

Electrocardiography was carried out during hypoxemia and graded exercise tests before and at intervals between 2 and 20 months after attempts to revascularize the heart by internal mammary artery implantation in 44 patients with angiographically documented coronary disease and angina pectoris. Eleven patients had single vessel disease; the right coronary was involved in seven of these patients. Thirteen patients had single vessel implants, employing the left internal mammary artery in 11 patients and a saphenous vein graft from the aorta in two. Thirty-one patients had double internal mammary artery implantation accompanied by gastroepiploic arterial implantation in four.Fifty per cent of the patients were symptomatically improved after surgery, the best results occurring in two patients with isolated anterior descending coronary disease. Of the 34 patients having postoperative coronary and mammary arteriography, 15% showed improvement which could be ascribed to mammary revascularization; 24% had limited myocardial revascularization and no symptomatic improvement; 29% had patent implants without development of collateral vessels, and the implanted vessels were occluded in 32%. Eleven of the 34 (32%) had fair or good symptomatic improvement in the absence of revascularization.The results of postoperative stress electrocardiography correlated closely with the findings on postoperative coronary and mammary angiography. The stress tests were persistently positive after operation in 83% of the patients having angiographically confirmed implant occlusion or nonrevascularization. The stress ECG response was reversed, becoming negative postoperatively, in five cases of angiographically proved significant revascularization. Thus, stress electrocardiography provided objective evidence of improvement in a small number of patients with limited coronary disease who developed good collateral circulation and correlated with the lack of revascularization in the majority even in those subjectively improved.

Nonaccredited Medical Education in the United States

The Kigezi International School of Medicine of Uganda and the Ross University School of Medicine in Dominica have recently announced their intentions to establish campuses in the United States. Ros...

Myocardial infarction in a fifteen year old boy

Abstract A fifteen year old boy, whose case is reported here, survived a myocardial infarction which was apparently related to strenuous exertion. The anatomic diagnosis, based on electrocardiographic and vectorcardiographic observations, was confirmed by coronary arteriograms which demonstrated marked narrowing of both major branches of the left coronary artery. The etiologic diagnosis of coronary atherosclerosis is suggested, primarily because of exclusion of other possibilities.