Kazuhiro Fujitani

Effects of left ventricular asynchrony on time constant and extrapolated pressure of left ventricular pressure decay in coronary artery disease

To elucidate the effects of ventricular asynchrony with or without myocardial ischemia on the time constant of left ventricular pressure decay and asymptote, that is, the level to which pressure would decrease if isovolumic pressure decrease continued infinitely, left ventriculography and pressure measurements were investigated in 14 normal subjects and 25 patients with coronary artery disease. Ventricular asynchrony was quantitated by the segmental area-time curve. This study consisted of two parts. 1) After a right atrial pacing stress test, the time constant and asymptote remained unchanged in eight normal subjects. In 18 patients with coronary artery disease and pacing-induced angina, asynchrony increased, the time constant was prolonged (64 +/- 13 to 94 +/- 17 ms, p less than 0.01) and the asymptote decreased (-22 +/- 10 to -46 +/- 20 mm Hg, p less than 0.01) after the pacing. 2) During right ventricular pacing at 80, 100 and 120 beats/min in the patients, asynchrony increased and the time constant was prolonged (55 +/- 7 versus 70 +/- 10, 47 +/- 11 versus 66 +/- 19, 36 +/- 7 versus 53 +/- 13 ms, respectively, p less than 0.01 versus right atrial pacing), whereas the asymptote was unchanged in six normal subjects compared with the value during right atrial pacing at each pacing rate. In seven patients with coronary artery disease, right ventricular pacing at 80, 100 and 120 beats/min also produced an increase in the time constant, while the asymptote was unchanged. Thus, prolongation of the time constant of left ventricular pressure decay may result from ventricular asynchrony even in the absence of myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

The relation between left ventricular asynchrony, relaxation, outward wall motion and filling characteristics during control period and pacing-induced myocardial ischaemia in coronary artery disease

To assess the relation between left ventricular asynchrony, relaxation, outward wall motion and filling in patients with coronary artery disease and normal systolic function, pressure measurements and left ventricular angiography were performed at rest and after pacing. Asynchrony and outward wall motion were quantified by segmental area-time curves. At rest, there were no differences in asynchrony and time constant between 10 patients with coronary artery disease and 10 normal subjects, while the early-filling rate was less in patients with coronary artery disease than in normal subjects. Six coronary artery disease patients with isolated left anterior descending disease displayed anterior outward wall motion which was less than that of normal subjects. In 10 coronary artery disease patients with pacing-induced angina, asynchrony increased, time constant prolonged and the early-filling rate decreased. In 6 coronary artery disease patients with isolated left anterior descending disease, anterior outward wall motion decreased after pacing. Thus, impaired early diastolic filling at rest in patients with coronary artery disease and normal systolic function may result not from asynchrony nor impaired relaxation, but from reduced regional outward wall motion of the affected area supplied by diseased coronary artery during early diastole. However, during ischaemia temporal asynchrony and impaired relaxation possibly add to left ventricular filling impairment in patients with coronary artery disease.