Left ventricular pressure-length relation during exercise-induced ischemia.

Abstract

The pressure-length relation in normal and ischemic segments was analyzed with use of left ventriculography and simultaneous micromanometry during supine exercise in 9 normal subjects and 12 patients with effort angina. Segmental analysis was done in the right anterior oblique projection using a long axis with three perpendicular, equidistant chords. The apical segment in the 12 patients with coronary artery disease represented the ischemic region. In 5 of the 12 patients with coronary artery disease, the basal segment that showed no exercise-induced deterioration in wall motion was used as an intrapatient control (nonischemic segment). In the 12 patients with coronary artery disease, left ventricular ejection fraction decreased (from 65% to 50%, p less than 0.001), end-diastolic pressure increased (from 24 to 40 mm Hg, p less than 0.001) and the lowest diastolic filling pressure increased (from 9 to 22 mm Hg, p less than 0.001) during exercise-induced ischemia. In normal subjects, ejection fraction increased (from 64% to 70%, p less than 0.01) with unchanged end-diastolic pressure, whereas the lowest diastolic filling pressure decreased during exercise (from 9 to 3 mm Hg, p less than 0.01). Global left ventricular diastolic pressure-volume curves showed an upward and rightward shift during exercise-induced ischemia. Regional pressure-length curves of both nonischemic (n = 5) and ischemic (n = 12) segments were shifted upward in early diastole, but moved to a higher portion of the rest pressure-length curve without an upward shift during mid- to end-diastole. In contrast, the apical segment in normal subjects showed a downward shift during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)