ROENTGENOGRAPHIC CLUES TO THE CARDIAC HEMODYNAMICS OF AORTIC STENOSIS.

Abstract

Although roentgenology has been employed for many years in evaluating patients with aortic stenosis, its use has been generally limited to making the anatomical diagnosis. As a result of our investigations into the hemodynamic significance of the radiological changes in aortic stenosis noted on conventional films (1, 2) and on angiocardiograms (3), we have found some clinically useful radiologic-hemodynamic correlations. These are herewith presented to assist in physiologic orientation in the interpretation of roentgenograms of patients with aortic stenosis. Clues to Hemodynamics of Aortic Stenosis on Conventional Films Diagnostic generalizations related to the radiologic-hemodynamic correlations in acquired and congenital aortic stenosis are presented in Table I and are depicted diagrammatically in Figure 1. These generalizations are based upon studies in 50 patients with acquired aortic stenosis (1) and 100 subjects with congenital aortic stenosis (2). The lesions were considered to be “pure” in that there was no evidence of significant aortic insufficiency, congestive failure, or a second cardiovascular defect. The radiological data were compiled with an arbitrary classification of the size of the left atrium, left ventricle, and ascending aorta. These were derived from conventional films of the chest (postero-anterior, lateral, and both obliques), taken with barium in the esophagus (1). Fluoroscopy was also utilized to verify calcification in the region of the aortic valve. Clues to Hemodynamics of Aortic Stenosis from Angiocardiography To assess the left ventricular hemodynamics in aortic stenosis from angiocardiograms measurements are made from the frontal end-diastolic film as shown in Figure 2. Line AB is drawn between the center of the aortic orifice, A, and the most distal point of the left ventricular cavity at the apex, B. Line XY, drawn perpendicular to AB at its midpoint, is taken as the diameter of the left ventricular cavity, C. Line YZ, obtained by extending line XY through the free wall of the left ventricle, measures the thickness of the left ventricular wall, W. No corrections are made for x-ray distortion since, in a previous study employing the same radiographic technics and equipment, the maximum variation in the degree of distortion was less than 10 per cent, and geometric distortion affects the values for C and W equally. The values obtained for C and W in each instance are corrected for patient size by dividing them by the body-surface area (B.S.A.) in square meters. Diagnostic generalizations related to the hemodynamic significance of the angiographic measurements of the left ventricular wall and cavity in aortic valvular and discrete subvalvular stenosis are presented in Figure 2. These generalizations are based upon a study of the angiocardiograms of 22 patients with aortic stenosis (15 valvular and 7 discrete subvalvular) and, as controls, 10 patients without left ventricular or aortic disease (3).