Dynamics of left ventricular filling at rest and during exercise

Left ventricular filling dynamics were examined at rest and during supine bicycle exercise in 33 patients at cardiac catheterization; 23 had coronary artery disease (ischemia group), five with prior infarction had an akinetic area at rest (scar group), and five had minimal cardiovascular disease (control). Peak filling rate and mean filling rate during the first half and second half of diastole were assessed by biplane angiography. Simultaneous micromanometer pressures were used to compute the time constant of isovolumic pressure decay (T). Peak filling rate and mean filling rate during the first half of diastole increased with exercise in all groups (from 615 to 1050 and 358 to 681 ml/sec in controls and comparably in the scar group and from 697 to 1035 and 347 to 768 ml/sec in the ischemia group). However, T was greater (reduced rate of pressure decay) with exercise in the ischemia group (38 vs 26 msec in controls; p less than .05). Changes in the atrial driving pressure for filling appeared to counterbalance the difference in T. Mean filling rate during the second half of diastole increased with exercise in controls and in the scar group but only modestly in the ischemia group (from 202 to 349 ml/sec). The reduction in late diastolic filling during exercise-induced ischemia was associated with increased filling in early diastole, with a middiastolic volume increase from 160 to 186 ml and an upward shift in the diastolic pressure-volume relation. Thus left ventricular filling is not impaired at rest in patients with coronary artery disease who have normal ejection fractions. Furthermore, the augmentation of early filling induced by exercise is not blunted but is maintained during ischemia, apparently at the expense of elevated left atrial pressure. However, late filling is restricted with ischemia by an increase in impedance.