Josef Edelstein

The electrocardiogram in obesity

The electrocardiographic abnormalities ascribed to morbid obesity were analyzed in a group of 144 patients without apparent clinical cardiovascular pathology and compared with a control group of 100 normal weight patients. Fifty-eight patients in the obese group were re-analyzed after significant weight loss and the electrocardiographic findings compared with their initial changes when they entered the program. The QRS voltage for the obese group was slightly lower than the voltage of the normal population; but in a significant number of the patients restudied after weight loss, the QRS voltage decreased (37 out of 58 patients). In inferolateral leads non specific flattening of the T wave was observed in the obese group (71/144); it became normal as they lost weight. The P and QRS axes of the obese group initially were within normal limits but more to the left; they moved slightly to the right, although still within normal limits as the patients lost weight. Two conclusions can be drawn from the study: a) low voltage is not a significant feature in the ECG of the obese and, b) the most consistent finding in obese patients is a flattening of the T wave.

The AV nodal Wenckebach phenomenon as a positive feedback mechanism

Abstract The AV nodal Wenckebach phenomenon is a manifestation of the operation of a positive feedback mechanism. As AV conduction for a given beat is retarded relative to that for the preceding beat, the action potentials of critical cells in the AV node are prolonged. Hence, the next cardiac impulse arrives at these cells earlier in the relative refractory period, causing still slower AV conduction and still greater action potential prolongation. This process continues until an impulse is blocked, whereupon the cycle begins anew. The positive feedback system may be represented graphically by a curve of the P-R interval plotted as a function of the R-P interval and by a straight line representing the R-P interval as a function of the P-R interval. The curve of P-R as a function of R-P is the forward element of the positive feedback loop, whereas the straight diagonal line describing R-P as a function of P-R is the feedback element of the loop. When the curve intersects the diagonal line, AV conduction will be stable. However, when the curve and diagonal line are displaced so that they no longer intersect, the Wenckebach phenomenon will supervene. The diagonal line will be displaced only by changes in heart rate, whereas the curve will be displaced not only by changes in heart rate but also by variations in autonomic neural tone, electrolyte concentrations, and the levels of certain drugs.

Ventricular septal aneurysms. A report of two cases.

Two cases of ventricular septal aneurysm are reported, one in the membranous septum and one in the muscular portion. The diagnosis was made by selective left ventricular angiography. It is suggested that these cases represent spontaneous closure of a ventricular septal defect with weakness and aneurysmal[see table in the PDF file]formation due to the high left ventricular pressure. Both are asymptomatic and hemodynamically within normal limits. Surgical repair of the aneurysms is not considered necessary.

Noninvasive Visualization of Right Coronary Artery Aneurysms

2 cases of right coronary artery aneurysm visualized with M-mode and cross-sectional echocardiography are described. Echocardiographic visualization of right coronary artery aneurysms is possible when substantial dilation is located proximally.

The postponed compensatory pause as a manifestation of positive feedback in atrioventricular conduction.

A patient with hypertensive cardiovascular disease was found to have unusual varieties of premature atrial and ventricular contractions. If the premature atrial contraction resulted in a greatly prolonged P-R interval, such that the increment in P-R exceeded the decrement in the preceding R-P, the next sinus P wave, occurring after a normal P-P interval, was found to be blocked. Also, numerous interpolated ventricular extrasystoles were observed in which the postextrasystolic P-R intervals were markedly prolonged and in which the compensatory pauses were postponed for one or two beats. We also present data from one dog in which a premature atrial activation produced a chain reaction such that complete A-V block occurred three beats later. We propose that the chain reaction which evoked the delayed block in the dog and the postponed compensatory pauses in the patient reflects the operation of a positive feedback mechanism in A-V conduction. Positive feedback is initiated by an extremely long P-R, which results in a very short R-P before the next cycle. This then leads to a still longer P-R, which then elicits a still shorter R-P. Block ultimately supervenes when the atrial activation wave arrives at the A-V junction during its effective refractory period.

Extraluminal or Intraluminal Inferior Vena Cava Occlusion in Pulmonary Embolism

Twenty-five cases of extraluminal and 47 of intraluminal inferior vena caval (IVC) occlusion for management of pulmonary embolism were reviewed. A comparison of results obtained with both methods suggests that the IVC umbrella filter provides the safer, more reliable means of IVC interruption in patients whose condition fulfills the criteria for caval occlusion. The simplicity of this technique and the fact that it can be performed under local anesthesia justify its consideration as the procedure of choice for IVC occlusion and permit its use in severely ill patients. On the basis of our positive findings, we now recommend that extraluminal occlusion be reserved for patients in whom insertion of the IVC umbrella is technically impossible.

Coronary Involvement After a Single Myocardial Infarction

Coronary angiography was performed in 95 patients 3 months to 3 years after a single myocardial infarction. The patients were categorized into 4 groups according to coronary angiography findings: grou

Acute Myocardial Infarction in a Young Female with Familial Hyperbetalipoproteinemia

A young woman, 21 years of age, suffered an acute transmural inferior wall myocardial infarction. EKG changes and serum enzymes accompanied a typical history. Coronary angiography perfomed 2 months after the acute episode showed complete occlusion of the right coronary artery and some mild disease of the circumflex and left anterior descending branches. Family history of type II hyperlipoproteinemia was present and she was known to have cholesterol since she was 12 years of age.