HEMODYNAMIC EFFECTS OF EXERCISE CATECHOLAMINE STIMULATION AND TACHYCARDIA IN MITRAL STENOSIS AND SINUS RHYTHM AT COMPARABLE HEART RATES

Seven patients with mitral stenosis and sinus rhythm were subjected to hemodynamic studies during supine exercise, infusion of isoproterenol and tachycardia, by right atrial pacing at comparable heart rates. During pacing, cardiac output did not change significantly, whereas it increased with exercise and infusion of isoproterenol. During pacing, the mitral valve diastolic pressure gradient and left atrial pressure increased because of a reduction in the diastolic filling period. The greatest increase in the mitral valve diastolic pressure gradient and left atrial pressure was during exercise. Pulmonary arteriolar resistance increased with exercise and pacing and diminished with infusion of isoproterenol. It is concluded that the hemodynamic effects of exercise on the stenotic mitral valve are the result of a combined influence of tachycardia and catecholamine stimulation. © 1969.