DIFFERENTIAL RESPONSES IN LEFT-VENTRICULAR DIASTOLIC FILLING DYNAMICSWITH ISOMETRIC HANDGRIP VERSUS ISOTONIC TREADMILL EXERTION

Although the hemodynamic responses to isotonic and isometric exercise are different, few data exist comparing the response of left ventricul ar (LV) diastolic filling dynamics with these two forms of exertion. T herefore we performed Doppler examination before and at the end of iso tonic and isometric exercise in 20 normal volunteers to define the dif ferential responses of LV filling to these two forms of exertion. Tran smitral inflow velocity signals from the apical view and phonocardiogr aphy were recorded before and at the termination of treadmill exercise (TRD) to 11 METs and handgrip (HG) (50% maximal for 2 minutes). Mean blood pressure (mBP), heart rate (HR), early diastolic (E) and late at rial (A) inflow velocities, mean acceleration rate (ACC) of E wave, ti me velocity integral of inflow (Ti), and isovolumic relaxation time (I RT) from second heart sound to onset mitral inflow were measured. Abso lute changes from baseline were significantly different for the two fo rms of exertion: TRD versus HG: BP = 11 +/- 9 versus 36 +/- 10 mm Hg, HR = 37 +/- 16 versus 16 +/- 9 beats/min, E = 11.6 +/- 11.3 versus -7. 0 +/- 9.4 cm/sec, A = 29.9 +/- 14.5 versus 14 +/- 12 cm/ sec, ACC = 16 4 +/- 151 versus -56 +/- 135 cm/sec(2), Ti = 1.9 +/- 3.0 versus -1.7 /- 1.7 cm, and IRT = -12 +/- 9 versus 9 +/- 10 msec, all p < 0.0001 ex cept for A, p < 0.001). Isotonic treadmill exercise resulted in enhanc ed early diastolic filling manifested by increases in E and ACC and a decreased in IRT. Conversely, isometric handgrip exercise produced evi dence of reduced early filling including decreased E and ACC and sligh tly increased IRT. Thus the response of LV filling dynamics recorded b y Doppler differs for isotonic and isometric exertion and likely refle cts the variable pressure and flow alterations induced by these two fo rms of exertion.