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

Abstract

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)

Effects of Postischemic Regional Left Ventricular Diastolic Wall Motion Abnormalities or Delayed Relaxation Following Coronary Vasospasm on Global Diastolic Function

“…25 In many patients with coronary artery disease and normal LV systolic function, impaired global diastolic filling may result from asynchronous LV regional diastolic function, which is a reversible manifestation of myocardial ischemia. 2,3,[26][27][28] In contrast, the present study demonstrated that none of the mitral Doppler indices including isovolumic relaxation times, transmitral E/A ratios and deceleration times differentiated patients following single vessel coronary vasospasm from control subjects. In patients with multivessel spasm, abnormal values were sometimes noted in those indexes but in no more than half of the cases.…”

New Parameter Derived from Three-Dimensional Speckle-Tracking Echocardiography for the Estimation of Left Ventricular Filling Pressure in Nondilated Hearts

“…10 Tau was calculated assuming non-zero asymptote in the data from the point of the minimum time derivatives of the LV pressure to the point at which pressure decreased to the level of the LV end-diastolic pressure. 11…”

Effects of graded reductions in coronary perfusion pressure on the diastolic pressure-segment length relation and the rate of isovolumic relaxation in the resting conscious dog.

“…Ischemia prolongs the rate of relaxation, but the degree of ischemia required and the mechanisms involved have yet to be elucidated.1 10 Similarly, there is general agree-ment that ischemia affects the extent of relaxation, but the details of this association are also obscure; in different experimental preparations, ischemia has had opposite effects on the diastolic pressurevolume or pressure-segment length relation.5'6,1'-23 These discrepancies could be at least partially due to the different definitions of ischemia used in the various experimental models, ranging from a total cessation of coronary blood flow in the isolated heart'to tachycardia-induced angina in patients with coronary artery disease. Thus, both the nature and the extent of the ischemic insult differ among the various preparations.…”