[Correlation of large artery stiffness and coronary flow velocity reserve].

OBJECTIVE: Coronary flow velocity reserve (CFVR) is an important indicator of coronary endothelial functions and microcirculation. Pulse wave velocity (PWV) reflects the degree of aortic sclerosis and it is an independent predictor of cardiovascular events. The present study was designed to evaluate the correlation of large artery stiffness and CFVR. METHODS: A total of 101 consecutive subjects were enrolled to measure the brachial-ankle pulse wave velocity (baPWV). According to the presence or absence of higher baPWV (> 1400 cm/s), they were divided into 2 groups. Transthoracic echocardiography was employed to measure coronary flow velocity in coronary left anterior descending (LAD). Then after an intravenous infusion of adenosine triphosphate, the velocity of blood flow was measured when the vessel was in maximal dilation. The ratio of flow velocity of those in maximal dilation to those at rest was CFVR. RESULTS: The subjects with a higher baPWV (> 1400 cm/s) were markedly elder and had higher risks of hypertension and diabetes. Thus age, hypertension and diabetes contributed to arteriosclerosis. More importantly, the subjects with a higher baPWV (> 1400 cm/s) had a much lower level of CFVR (2.66 ± 0.74 vs 2.95 ± 0.76; P < 0.01) than those with a lower baPWV (< 1400 cm/s). Furthermore correlation analysis showed that CFVR and baPWV levels were significantly negatively correlated (r = -0.35, P < 0.01). CONCLUSIONS: A negative correlation exists between artery stiffness and coronary flow velocity reserve. The increased vascular stiffness may impair coronary endothelial function, cause the dysfunction of coronary microcirculation and raise the risks of cardiovascular events.

[Left ventricular flow vector characteristics and the relationship between flow vector and left ventricular systolic function in patients with anterior myocardial infarction].

OBJECTIVE: To assess left ventricular vortex and flow vector features and the relationship between vector flow and left ventricular systolic function in patients with anterior myocardial infarction by echocardiography-derived vector flow mapping (VFM). METHODS: Echocardiography was performed in 31 patients with anterior myocardial infarction and 20 healthy controls. Flow vector and velocity of left ventricle were analyzed on apical 3 chambers view with color Doppler. RESULTS: (1) Left ventricular intracavitary vortex during isovolumic contraction phase could be detected in both groups. Vortex was detectable also during contraction phase and relaxation phase in patients with myocardial infarction. There was no vortex during contraction phase, and there was only small and transit vortex during relaxation phase in control group. (2)Flow vector of apex and middle segments directed to apex and was opposite to that of basal segment of left ventricle in patients with myocardial infarction and in controls [(10.6 ± 8.3) cm/s vs. -(5.8 ± 7.2) cm/s, (19.5 ± 11.8) cm/s vs. -(16.6 ± 14.7) cm/s]. During rapid relaxation phase, the velocity in apex was lower in patients with myocardial infarction than that in control group [(6.8 ± 9.8) cm/s vs. (17.6 ± 15.8) cm/s, P < 0.01]. (3) There was a negative correlation between velocity in apex and left ventricular ejection fraction (LVEF) during rapid eject phase in patients with anterior myocardial infarction (r = -0.52, P < 0.05). Velocity in apex of patients with LVEF < 50% was higher than that of patients with LVEF ≥ 50% during rapid eject phase [(13.5 ± 9.0) cm/s vs. (5.8 ± 5.1) cm/s, P < 0.05]. CONCLUSIONS: Vortex period is prolonged in patients with anterior myocardial infarction compared to normal controls during whole cardiac cycle, flow vector of apex and middle segments is directed to apex during eject phase and there is a negative correlation between velocity in apex and LVEF during rapid eject phase in patients with anterior myocardial infarction.