Pulsus alternans: Its influence on systolic and diastolic function in aortic valve disease

Left ventricular high fidelity pressure measurements and simultaneous biplane cineangiocardiography were performed in 12 patients with severe aortic valve disease (aortic stenosis in 10, aortic insufficiency in 1 and combined valve lesion in 1). Left ventricular contractility was estimated from maximal rate of left ventricular pressure rise (max dP/dt), peak measured velocity of contractile element shortening (Vpm) and mean circumferential fiber shortening velocity. Left ventricular relaxation was assessed in 12 patients from the time constant (T) of the decline in left ventricular pressure; this constant was calculated from a nonlinear regression analysis of pressure and time (method 1) and a linear regression analysis of pressure and negative dP/dt (method 2). Left ventricular diastolic function was evaluated in nine patients from simultaneous diastolic pressure-volume relations during the strong and weak beats.During pulsus alternans, heart rate and left ventricular end-diastolic pressure remained unchanged, whereas peak systolic pressure (220 versus 204 mm Hg, p < 0.01) and end-systolic pressure (101 versus 95 mm Hg, p < 0.01) were significantly higher during the strong beat than during the weak beat. Max dP/dt was alternating 2,162 versus 1,964 mm Hg, p < 0.05), whereas the peak velocity of contractile element shortening remained unchanged (1.21 versus 1.18 ML/s). Systolic shortening of the left ventricular minor axis was significantly (p < 0.02) greater during the strong (24%) than during the weak (19%) beat, but that of the left ventricular major axis remained essentially unchanged (8 versus 7%). The time constant (T) demonstrated only slight alternation during the strong beat (method 1: 54 ms, method 2: 58 ms) and during the weak beat (method 1: 57 ms, method 2: 67 ms, p = NS). Diastolic pressure-volume relations showed no changes during pulsus alternans. Left ventricular end-diastolic volume was 148 ml/m2during the strong and 146 ml/m2 during the weak beat; systolic ejection fraction was significantly higher during the strong than during the weak beat (48 versus 43%, p < 0.02).It is concluded that pulsus alternans is a systolic phenomenon with alternation in left ventricular contractility, but nonsignificant changes in left ventricular relaxation and diastolic function. Although contractility was enhanced, the time constant (T) of the decline in left ventricular pressure did not change significantly during the strong beat, because the increase in peak systolic pressure offset almost completely the decrease in T associated with the increase in contractile state. The alternation of systolic shortening is the result of changes in contractility and not of a Frank-Starling mechanism since preload remained unchanged