Norman Krasnow

Continuous ventricular dimensions in man during supine exercise and recovery. An echocardiographic study.

Abstract Ten healthy men aged 18 to 23 years performed supine bicycle ergometer exercise during continuous echocardiographic recording. Beat to beat analysis of ventricular dimensions revealed that during constant work load exercise end-diastolic dimension did not change and end-systolic dimension decreased insignificantly by 4 percent. The stroke dimension and fractional shortening of the ventricular dimension rose 7 and 5 percent, respectively. During recovery, end-diastolic dimension and stroke dimension increased above the resting value, beginning 26 seconds (range 16 to 45) after cessation of exercise, whereas heart rate fell promptly to resting levels by 37 seconds. The peak increase in end-diastolic dimension and stroke dimension averaged 11 and 35 percent, respectively. Endsystolic dimension coincident with peak end-diastolic dimension decreased 11 percent in 6 of 10 subjects, and was unchanged in four. Fractional shortening of the ventricular dimension increased 8 percent (P These dimensional changes indicate a significant increase in end-diastolic dimension and stroke dimension in all 10 subjects during the recovery phase of supine exercise with a parallel rise in the percent shortening of the ventricular dimensions. During exercise a clear Frank-Starling effect is masked, whereas during recovery the continuing high level of venous return is dissociated from the decreasing heart rate, resulting in a transient increase in end-diastolic volume and a measurable Frank-Starling effect.

Hypertrophic cardiomyopathy in the aged.

Although usually considered a disease of young or middle-aged adults, hypertrophic cardiomyopathy is not infrequently seen in older patients as well. Twenty of 23 cases of hypertrophic cardiomyopathy seen in the past 2 1/2 years at our institution have been in patients whose average age was 65 years, and who ranged up to 76 years. Sixteen of these had evidence of an obstructive component at cardiac catheterization or echocardiography. Symptoms and signs were similar to those described for the younger patients in the literature, but were often attributed to other causes, including valvular aortic stenosis, arteriosclerotic or hypertensive heart disease, or cerebrovascular disease. Left ventricular hypertrophy was more consistently present on ECG than on x-ray. The not-infrequent occurrence of hypertrophic cardiomyopathy in older patients, predominantly females, indicates that the natural history of this disease includes a group who suffer few or no symptoms until late in life. Clinical management of younger patients with this diagnosis should be considered in light of this more favorable possible course.

Effects of lanthanum and gadolinium ions on cardiac sarcoplasmic reticulum.

The tervalent rare earth cations lanthanum (La3+) and gadolinium (Gd3+) have been studied for their effect on canine cardiac sarcoplasmic reticulum. At dose-related concentrations above 10 μM, La3+ and Gd3+ inhibit calcium binding non-competitively, decrease the velocity of calcium uptake (in presence of oxalate), and inhibit the Ca2+-activated Mg2+-ATPase. The tendency for sarcoplasmic reticulum inhibition by excess Ca2+ is accentuated by lanthanides. The effect of the lanthanides is time-dependent, inhibition diminishing during incubation. Since effects were observed in the presence of oxalate, the reactive lanthanide ion concentration is not as predicted from solubility-product considerations.

Cardiovascular Status in Long-Term Hemodialysis Patients: An Exercise and Echocardiographic Study

To determine any adverse effects on cardiac performance resulting from long-term hemodialysis, 10 patients treated for 5 or more years (mean 8.4 years) were evaluated by exercise testing and echocardiography. Treadmill stress testing was performed to exhaustion with EKG monitoring according to the Bruce multistage protocol, while maximum oxygen consumption (VO2max) was measured directly. 1 patient had equivocal evidence for myocardial ischemia but did not experience angina. 8 of the 10 subjects had both VO2max and echocardiographic indices within the normal range established for large groups of controls. The other 2 had EKG and radiologic evidence of cardiac enlargement and had had sustained hypertension.

Isolated toxoplasma myocarditis in acquired immune deficiency syndrome

The recognition of cardiac involvement in acquired immune deficiency syndrome (AIDS) has increased. Disseminated toxoplasma involving the heart has been reported; here a case of isolated cardiac toxoplasma myocarditis that led to fatal cardiac tamponade is described. This is the rist reported case of isolated cardiac toxoplasma in AIDS

Treatment of cardiac arrhythmias with beta-adrenergic blocking agents: Clinical and experimental studies☆

Abstract Twenty-seven subjects with various cardiac rhythms were treated with intravenous pronethalol or propranolol. Slowed sinus rhythmicity, decreased A-V node conduction, and decreased ventricular premature contractions (particularly if caused by digitalis) were observed. One death occurred in a patient with A-V dissociation, severe pulmonary hypertension, and congestive heart failure. No other significant side effects were seen. These two drugs are considered to be quite useful in controlling ventricular responses to atrial flutter or fibrillation, and in certain cases of ventricular irritability. They are rapid acting and potent. Their use may be hazardous when bradycardia or A-V dissociation is present, or if the arrhythmia is complicated by severe congestive heart failure or bronchospastic pulmonary disease. Data in animals confirm the reversal of digitalis toxicity and suggest a mechanism of action in addition to beta-adrenergic blockade.

Fatigue, Acid-Base and Electrolyte Changes with Exhaustive Treadmill Exercise in Hemodialysis Patients

Aerobic conditioning exercises have been shown to be beneficial for maintenance hemodialysis patients, but biochemical changes during exhaustive exercise in these functionally anephric patients have been less thoroughly studied. We evaluated serum biochemical changes in 7 patients during and after treadmill exercise to patient exhaustion. Duration of exercise was limited by lower leg fatigue without claudication. At exhaustion, only mild changes from baseline rest values were noted in arterial pH (7.39 +/- 0.03-7.33 +/- 0.04) and lactate (0.94 +/- 0.3-5.73 +/- 2.68 mmol/l) despite normal exercise-induced intracellular fluid shifts as evidenced by albumin concentration increases (44.9 +/- 2.8-49.3 +/- 3.1 g/l). Increases in serum K+ concentrations are also modest (change in K from baseline = 0.87 +/- 0.22 mmol/l). An explanation for these minimal biochemical alterations at exhaustion is unclear, but could relate to exercise being limited well below estimated maximum cardiac output and muscle O2 extraction levels by early, unexplained muscle fatigue. Fatigue in hemodialysis patients does not appear to be due to muscle hypoxia.

Myocardial anaerobiosis in anemia in uremic man.

Myocardial anaerobic metabolism (lactate production) has been previously observed in man primarily in ischemic heart disease. Myocardial lactate balance was studied in severe anemia in 6 stable uremic patients receiving maintenance hemodialysis before and after transfusion. They were young, aged 21 to 31, and had no evidence of heart disease or angina pectoris. At rest, the mean extraction coefficient for lactate by the myocardium (A-V/A)L was abnormally low at —1.2 percent (range 14.3 to —18.9 percent). Intravenous isoproterenol infusion (2 to 8 μg/min) resulted in definite anaerobiosis in all patients, mean (A-V/A)L —29.9 percent (range —1.5 to —76.5 percent). After transfusion, the extraction coefficient at rest was normal, mean 22 percent (range 11 to 39 percent), and decreased with isoproterenol infusion but remained positive in 5 of 6 patients. Electrical pacing (mean heart rate 148 beats/min) before transfusion increased the average extraction coefficient from 5.9 percent at rest to 7.9 percent; after transfusion, extraction increased from 22.9 percent to 34.3 percent. Exercise changes were not significant. Lactate/pyruvate ratio tended to increase from artery to coronary sinus during stress, before transfusion. There was improvement in the extraction coefficient for lactate with transfusion, without alteration of the uremic state. Cardiac index and systolic ejection rates indicated a hyperkinetic circulation at rest, increased by isoproterenol and exercise, and decreased by transfusion. Compensatory myocardial anaerobiosis may thus occur in physiologically stable anemic uremic patients with normal hearts and without development of angina.

Lanthanide binding to cardiac and skeletal muscle microsomes: Effects of adenosine triphosphate, cations, and ionophores☆

Abstract Lanthanide (gadolinium, Gd) binding to cardiac and skeletal muscle microsomes was studied, and high- and low-affinity sites were identified. The high-affinity constant was 10 6 M −1 , and there were 131 and 107 nmol/mg bound to this site in dog heart and rabbit skeletal muscle, respectively. Zn 2+ , Cd 2+ , Al 3+ , and Ca 2+ (5 m m ) inhibited binding, especially of the high-affinity site. Ionophores X537A (10 μ m ) and A23187 (1–2 μ m ) increased lanthanide binding and did not cause release. Addition of ATP in low concentration (20–50 μ m ) increased the binding of Gd without hydrolysis of the ATP. The extra binding induced by ATP was blocked by heating the microsomes and was reversed by [ethylenebis(oxyethylenenitrilo)]tetraacetic acid. High concentrations (10 −4 –10 −3 , m ) of ATP blocked extra Gd binding by competitive chelation. The Ca 2+ -activated ATPase was inhibited by Gd and stimulated by X537A. The Gd did not block the ionophore-stimulated increase in Ca 2+ -ATPase activity. It is postulated that lanthanides bind predominantly to the ionophoric component of the Ca-transport site rather than the hydrolytic site and that ATP may facilitate such binding without being split.

Double Orifice Mitral and Tricuspid Valves

Atrioventricular valve duplication is a rare congenital cardiac anomaly. The anomaly is usually recognized as an incidental finding at autopsy, open heart surgery, or two‐dimensional echocardiography. In this article we present the transthoracic and transesophageal presentation of a case of mitral and a case of tricuspid valve duplication. The hemodynamic consideration of the lesions is discussed with a review of the literature.