Effects of inotropic stimulation on segmental left ventricular relaxation quantified by color kinesis

Abstract

Although myocardial ischemia impairs left ventricular (LV) relaxation before contractile function, regional LV diastolic dysfunction is difficult to evaluate by conventional echocardiography. Because β-adrenergic stimulation enhances myocardial relaxation, we sought to characterize segmental LV diastolic function (by color kinesis) during dobutamine stress echocardiography and compare it with independently assessed segmental systolic function. We studied 22 patients with suspected coronary artery disease with color kinesis by acquiring digital images with endocardial motion display throughout diastole. Quantification of LV segmental diastolic peak filling rate (SPFR, normalized to segmental end-diastolic area/s) was obtained at rest, low-dose, and peak dobutamine infusion in myocardial segments visualized from the short-axis and/or apical 4-chamber views. In patients with resting normal LV systolic function and a dobutamine-induced hypercontractile response (group I, n = 13 patients; 102 segments), progressive increases in SPFR (p <0.001) were seen in all segments. However, in LV segments with resting systolic wall motion abnormalities (group II, n = 9 patients; 74 segments) SPFR measured at rest was significantly lower than that in group I (p <0.005) and did not increase significantly in response to dobutamine. In both groups of patients, LV myocardial segments (n = 528; rest and after dobutamine)—systolic and quantitative diastolic function—were concordant in 84% and 77% as viewed from short-axis and apical views, respectively. Thus, segmental LV diastolic function can be measured with color kinesis at rest and after inotropic stimulation, allowing comparison with segmental systolic function during pharmacologic stress testing.