PATHOPHYSIOLOGY AND NATURAL HISTORY CONGESTIVE HEART FAILURE Arterial wave reflection in heart failure

Arterial wave reflection may adversely influence both left ventricular afterload and ejection performance. Therefore, using multisensor catheter manometers, we derived wave reflection indexes from ascending aortic pressure and velocity recordings in 17 subjects with clinical heart failure secondary to idiopathic dilated cardiomyopathy and 11 control subjects free of detectable cardiovascular disease. Patients were studied at rest as well as during submaximal supine bicycle exercise. Eight of the subjects with cardiomyopathy were also studied during infusion of nitroprusside at rest and on exercise. Reflection indexes decreased on exercise in normal subjects but did not consistently do so in the subjects with heart failure. In both groups the reflected wave on exercise returned earlier during the ejection period. Infusion of nitroprusside at rest in subjects with heart failure had dramatic, and significant, effects on the magnitude and timing of arterial wave reflections. The effect of nitroprusside on reflection magnitude persisted on exercise, although the timing of the reflected wave was disadvantageous. The systemic arterial response to exercise in heart failure is characterized by a smalier change in wave reflection indexes in spite of a comparable decrease in systemic vascular resistance. Nitroprusside diminishes the potentially adverse impact of wave reflections by decreasing the magnitude of the reflected wave and altering its timing. Additional dose titration studies are necessary to fully assess the benefits of pharmacologic vasodilation during exercise. Circulation 75, No. 4, 711-722, 1987. THE PRESENCE of arterial wave reflections may be inferred from characteristic alterations in the pressure pulse as it propagates along the aorta. 1-6 Both the magnitude and timing of the reflected wave(s) are important in assessing their potential physiologic significance. Since a reflected pressure wave adds to the forward wave, a wave returning during systole would increase ventricular afterload. Reflected flow waves, however, subtract from the forward flow pulse. Therefore a wave returning during systole diminishes net forward flow and is disadvantageous to ventricular ejection. Changes in systemic vascular resistance have been shown to result in corresponding changes in the reflection properties of the arterial tree. A decrease in peripheral resistance may decrease wave reflections, whereas an increase in peripheral resistance enhances wave reflections.7-9 However, reflections may diminish in the absence of alterations in peripheral resistance.t0 An increase in systemic vascular resistance is a charFrom the Cardiac Catheterization Laboratory, Hospital of the University of Pennsylvania and the University of Pennsylvania School of Medicine, Philadelphia. Address for correspondence: Warren K. Laskey, M.D., Cardiac Catheterization Laboratory, Hospital of the University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104. Received April 2, 1986; revision accepted Dec. 26, 1986. Vol. 75, No. 4, April 1987 acteristic feature of congestive heart failure.1t We reasoned that physiologic or pharmacologic decreases in systemic vascular resistance might result in corresponding, and hopefully beneficial, changes in the reflection characteristics of the arterial tree. Maneuvers that alter the magnitude of reflected waves may also effect a change in their timing. Thus the overall effect(s) of systemic vasodilation may be difficult to predict. To this end, we compared the magnitude and timing of arterial wave reflections in normal subjects, at rest and on exercise, with those in subjects with congestive heart failure. The effects of nitroprusside in the latter subjects were also analyzed to compare physiologic and pharmacologic arteriolar vasodilation in heart failure.