Howard L. Moscovitz

The Hemodynamics of the Left Side of the Heart as Studied by Simultaneous Left Atrial, Left Ventricular, and Aortic Pressures; Particular Reference to Mitral Stenosis

At operation the hemodynamics of the left side of the heart were studied in six patients without mitral stenosis, and in eight patients with mitral stenosis, by means of simultaneous needle puncture of the left atrium, left ventricle, and aorta. This technic permits analysis of the various phases of the cardiac cycle in normal subjects and in patients with mitral stenosis. The fundamental hemodynamic expression of mitral stenosis is the presence of an elevated left atrioventricular filling pressure sure gradient, which ranged from 4 to 20 mm. Hg, and after valvulotomy fell in relation to the adequacy of the procedure.

Pressure Events of the Cardiac Cycle in the Dog Normal Right and Left Heart

Simultaneous pressure curves from the cardiac cavities, aorta and pulmonary artery of dogs were recorded by manometers of equal sensitivity. It was found that left ventricular pressure during ejection is practically identical with that of the aorta. In the majority of dogs atrial and ventricular end-diastolic pressures were equal. The temporal relations of events in the right and left heart were similar to those reported in man, but the duration of the cardiac cycle is too dependent on cycle length to permit comparison.

Should the transvalvular gradient in aortic stenosis be measured

Cardiologists experienced in the techniques of cardiac catheterization approach this procedure with more than usual caution in patients with tight aortic stenosis. This is true because of the increased risk in retrograde passage of the aortic catheter through a calcified, stenotic valve. Dislodgment of calcium emboli, failure to traverse the diminutive, eccentric orifice and the frequent production of catheter-induced arrhythmias in ventricles with hypertrophied walls and small cavities are commonplace in aortic stenosis. The alternate transseptal approach to the left atrium and ventricle is also risky since the left atrium is generally smaller in aortic stenosis than in mitral disease. For these reasons, it would be most welcome to devise a reliable, noninvasive index which would match in accuracy the direct measurement of the pressure gradient across the aortic valve. Eddleman et al. 1 in the June issue of this Journal have at tempted to correlate the clinical features of aortic stenosis with the hemddynamic data obtained in these patients at cardiac catheterization. From their studies, it appears that one need not perform catheterization studies in patients who have (1) slow-rising carotid upstroke, (2) calcific aortic valve, and (3) left ventricular hypertrophy as manifested by a thrusting apical impulse and inverted T waves on the electrocardiogram. Such patients, according to these authors, will have a transaortic systolic ejection gradient exceeding 50 mm Hg, and the risks of cardiac catheterization may be avoided in the preoperative assessment of patients for aortic valve surgery. Similarly, Bache et al. 2 demonstrated that, if the aortic ejection time was not prolonged beyond that predicted from stroke volume, the aortic valve area was greater than 0.75 cm 2 and surgery was not required. The general experience of other investigators is somewhat at variance with this view. Friedman et al., 3 utilizing serial hemodynamic observations, con-

Pericardial constriction versus cardiac tamponade

Since numerous hemodynamic studies of constrictive pericarditis and cardiac tamponade have appeared in the literature, it is surprising that many of the mechanisms responsible for the cardinal clinical features remain obscure. Points needing clarification include pulsus paradoxicus (which, of course, is not paradoxical at all but rather an accentuation of a normal phenomenon), ascites praecox, the loud diastolic knock in pericardial constriction and the exact nature of the phasic pulmonary and systemic pressure relationships with respiration. Whether or not myocardial contractility is irreversibly impaired by prolonged pericardial constriction is still a moot p0int.l common, and the persistence of near normal pulsation on electrokymography does not rule out the diagnosis of constrictive pericarditis. “Acute pericardial constriction”, a sequella of viral pericarditis or irradiation, although infrequent, may prove to be a difficult differential diagnosis from cardiac tamponade due to a rapidly accumulating effusion.

Echocardiographic features of experimental left atrial tumor

Abstract An experimental technique for simulating left atrial tumors and their echocardiographic features is described. The echocardiographic demonstration of tumor movement between atrium and ventricle was noted in all cases and reliably detected the tumor. A normal E-to-F slope could be seen in the presence of a tumor. A notch or plateau was at times found on the AC component of the mitral valve echo and its hemodynamic implications are discussed. The controversy concerning whether blood or tumor enters the left ventricle first during diastole is resolved in favor of the former. The demonstration of tumor, mitral leaflet, and ventricular-septal contact provides a possible explanation for the presence of mitral valve lesions and tumor emboli in left atrial myxoma.

Original communicationThe pressure events of the cardiac cycle in the dog: Aortic valve lesions☆

Abstract 1. 1. The technique of simultaneous equisensitive pulse pressure recording was applied to a group of 29 dogs in which aortic stenosis, aortic insufficiency, combined aortic stenosis and insufficiency, and aortic coarctation were acutely created. In addition, the transformation of the central into the peripheral pulse in these lesions was studied. 2. 2. The effect of superimposing stenosis on normal and insufficient aortic pulses was to narrow the pulse pressure, delay the systolic peak, and produce a prominent anacrotic notch in a lowered position on the ascending limb. The contour characteristics of aortic insufficiency were dominated and masked by the superimposed stenosis, although the maintenance of a low diastolic pressure indicated that insufficiency was present. 3. 3. As the normal central pulse was transformed into the peripheral, the anacrotic shoulder rose to become a primary peak. In aortic stenosis, however, the anacrotic notch retained its low position on the ascending limb, although its features became less clear as the central pulse moved peripherally. 4. 4. The anacrotic notch or pause was a synchronous and superimposable event on the aortic and ventricular pulses in the normal, in aortic insufficiency, and in aortic coarctation. When aortic stenosis was produced alone or in combination with aortic insufficiency, the anacrotic notch on the aortic curve was separated from a synchronous vibration on the ventricular curve by a pressure gradient.

Hemodynamic Studies in Digitalis-Induced A-V Dissociation in the Dog*

Abstract A-V dissociation was studied by utilizing the intracardiac phonocardiogram, intracardiac pressure pulses and the electrocardiogram, in dogs that were intentionally overdigitalized with intravenous digoxin. Digitalis is capable of inducing A-V dissociation that can be reversed with potassium chloride. Atrial activity maintains its independence in this arrhythmia. The variable pattern of atrial contraction while the atrioventricular valves are open or closed is demonstrated during A-V dissociation.