Intraventricular early diastolic filling during acute myocardial ischemia, assessment by multigated color m-mode Doppler echocardiography.

Abstract

Color M-mode Doppler echocardiography has been suggested as a new noninvasive technique for assessing left ventricular diastolic function. The present study investigated intraventricular filling pattern by color M-mode Doppler in patients during percutaneous transluminal coronary angioplasty (PTCA). In a dog model of myocardial ischemia, the color M-mode flow pattern was related to indices of global and regional myocardial function. From color M-mode images, the time difference (TD) between occurrence of peak velocity in the apical region and at the mitral tip was determined in 20 patients and eight anesthetized dogs during coronary occlusions. During PTCA, the timing of peak velocity was progressively delayed from mitral valve to apex. Consistent with this, the dog model showed delayed apical filling during coronary occlusion; TD increased from 18 +/- 4 to 71 +/- 9 milliseconds (P < .01). In the ischemic region, systolic shortening (sonomicrometry) decreased from 20 +/- 3% to -5 +/- 2% (p < .01). The one-third filling fraction decreased from 59 +/- 5% to 31 +/- 6% (P < .01) and correlated with TD (r = .85, P < .01). The time constant of isovolumic relaxation (tau) increased slightly and correlated with TD (r = .81, P < .01). Pacing tachycardia, caval constriction, and volume loading were performed to mimic the ischemia-induced changes in heart rate, stroke volume, and intracavitary filling pressure, respectively. There were no significant changes in TD or tau during these interventions. Color M-mode Doppler echocardiography showed a marked delay of apical peak filling velocity during PTCA. The experimental data suggest that this reflects retarded filling of the ischemic ventricle. Thus, color M-mode Doppler may provide a useful method for assessing diastolic dysfunction.