Regional myocardial function is not affected by severe coronary depressurization provided coronary blood flow is maintained

Abstract

It has been suggested that vasodilation distal to a stenosis may cause a profound decrease in perfusion pressure and adversely affect regional left ventricular function. This phenomenon could explain the clinical concept of reversal of regional dysfunction by coronary revascularization. To evaluate the hypothesis that regional myocardial function parallels regional coronary blood pressure in the absence of changes in coronary flow, dogs chronically instrumented with left circumflex coronary artery flow probes, cuff occluders, pressure catheters and segmental function sonomicrometers were studied. By decreasing regional coronary vascular resistance with selective intracoronary dipyridamole and controlling blood flow with a proximal coronary cuff occluder, the mean left circumflex artery pressure was reduced from 83 +/- 3 to 38 +/- 2 mm Hg while circumflex coronary blood flow was maintained constant. Regional contractile function as measured by circumflex sonomicrometers was unchanged at constant circumflex subendocardial blood flow as measured by radioactive microspheres. These findings suggest that regional contractile function is dependent on subendocardial blood flow and is independent of coronary perfusion pressure.

Integrated Myocardial Perfusion Imaging Diagnostics Improve Detection of Functionally Significant Coronary Artery Stenosis by 13 N-ammonia Positron Emission Tomography

“…Fourth, it should be noted that there have been numerous studies representing the discordance between FFR and CFR, regardless of methodologies, such as invasively measured CFR or noninvasively measured-CFR by PET, cardiac MR, myocardial contrast echocardiography or contrast CT. 42 Like those studies, the correlations between FFR and invasively measured CFR (r=0.364, P<0.001) and between FFR and PET-derived CFR (r=0.384, P<0.001) were modest in our study. Although we focused on the association of PET-derived measures with FFR, the discrepancy between pressure-derived and flowderived measures, as well as the limitations of FFR, 13,47 need to be considered in the definition of myocardial ischemia. Fifth, although most of the previous PET studies used intravenous infusion of adenosine as a hyperemic agent, 4,22,23 the possible confounding effect of decreased driving pressure by adenosine infusion on coronary flow needs to be considered.…”

Intense Exercise and Native Collateral Function in Stable Moderate Coronary Artery Disease

“…Myocardium tolerates perfusion pressure to <30 to 35 mm Hg without ischemia. [2][3][4][5] The moderate stenosis of this study had FFR averaging 0.63±0.1 during adenosine hyperemia that causes maximal pressure gradient more than exercise. With an average systolic pressure of 136±23 mm Hg, the FFR of 0.63 indicates a coronary perfusion pressure of 86 mm Hg during adenosine hyperemia.…”

Fractional Flow Reserve Returns to Its Origins

“…We have hypothesized based on intact myocardial function at low perfusion pressures when flow remains normal 14 plus good clinical outcomes data for high CFR 15 that deferring revascularization for lesions with a low FFR but intact CFR is reasonable to explore in the setting of a clinical trial (DEFINE-FLOW, clinicaltrials.gov NCT02328820). FFR Returns to Its PET Origins…”