Assessment of coronary flow velocity reserve by transthoracic Doppler echocardiography before and after coronary artery bypass grafting

Coronary flow reserve from mouse to man--from mechanistic understanding to future interventions

Myocardial ischemia is recognized as an important mechanism increasing the risk for cardiovascular events in both symptomatic and asymptomatic patients. In addition to obstructive coronary diseases, systemic inflammation, macro- and microvascular function are additional important mechanisms contributing to the ischemic myocardium. Accumulating evidence indicates that coronary flow reserve (CFR) is a quantitative measurement of ischemia including integrated information on structure and function of the coronary artery at all levels. Not surprisingly, CFR has been shown to confer strong prognostic value for hard cardiovascular (CV) events in a number of relevant patient cohorts. Using high-resolution imaging, it is now possible to study coronary arteries from mouse to man. Therefore, CFR may be an important translational tool to risk-stratify patients and to perform both preclinical and clinical proof-of-concept studies before investing in large-scale outcome trials, thus improving the translational value for novel CV targets.

Comparison between adenosine and isoflurane for assessing the coronary flow reserve in mouse models of left ventricular pressure and volume overload

Adenosine and high-concentration isoflurane are commonly used to induce hyperemia for assessment of coronary flow reserve (CFR) in mice, but high-concentration isoflurane may exacerbate cardiac dysfunction, leading to impaired CFR. However, there is no study be found comparing the effects of adenosine and isoflurane on CFR and corresponding cardiac function. High-resolution echocardiography and invasive hemodynamic assessment were performed in 20 mice 2 wk after transverse aortic constriction (TAC), aortic regurgitation (AR), and corresponding sham operation. CFR was calculated as the ratio of hyperemic to basal peak diastolic velocity (CFRpdv) or diastolic velocity-time integral (CFRdvti). In the sham-operated mice, no differences were observed between the effects of adenosine and isoflurane on CFR, left ventricular systolic function (left ventricular ejection fraction and fractional shortening), left ventricular end-systolic pressure, maximal contraction and relaxation velocity (+dp/dt and -dp/dt), alteration of left ventricular pressure (ΔLVP), or ±dp/dt (Δdp/dt). But adenosine-derived results were significantly higher than isoflurane-derived ones in both the TAC and the AR groups. Moreover, CFRpdv or CFRdvti was positively correlated with both LVEF and LVFS. Compared with adenosine-derived CFR, isoflurane-derived CFR may be underestimated in the TAC and the AR mice, which is probably associated with suppressed cardiac function.