Figure 10

Force-frequency relationship in the cath lab. During a pressure-volume loop study the contractility was quantified at baseline and during heart rate increase (atrial pacing). At each incremental heart rate the upper left corners of the loops define the LV end-systolic pressure-volume relation (ESPVR). The slope of the ESPVR is the end-systolic elastance (Ees). Upper left panel. During atrial pacing in a control subject (Control) for higher heart rates the ESPVR is shifted leftward, and Ees increases: contractility increases as heart rate increases. Upper right panel. A patient with severe LV hypertrophy (Hypertensive cardiomyopathy) displays a decrease in the ESPVR slope for heart rate increases: from 70 to 100 bpm and at further increases in heart rate (from 100 to 120 and to 150 bpm): contractility decreases at higher heart rates. Lower panel. For each study group end-systolic elastance (Ees, mean value ± SD) is plotted at different heart rates during rapid atrial pacing; for the 8 control (controls, non-LVH) patients, the Ees increased with each increment in heart rate. In contrast, Ees fell at faster rates in hypertensive (HYP) subjects. (Modified from: Liu C. Diminished contractile response to increased heart rate in intact human left ventricular hypertrophy. Circulation 1993; 88:1893)