Effect of Coronary Stenosis on Adjacent Bed Flow Reserve

Abstract

Background-During coronary stenosis, flow reserve in the adjacent nonstenotic bed decreases, but the microvascular mechanisms are unknown. Because myocardial contrast echocardiography (MCE) assesses microvascular physiology, we used it to relate flow reserve to intramyocardial blood volume in the adjacent bed. Methods and Results-A noncritical left anterior descending (LAD) stenosis was created in 10 dogs. MCE was performed and myocardial blood flow was measured with neutron-activated microspheres and flow probes. Data were collected at baseline, hyperemia, and hyperemia and stenosis. Hyperemia was induced with an A 2A receptor agonist. MCE acoustic intensity in the LAD and left circumflex (LCx) regions were fit to the following: yϭA(1-e Ϫ␤t ), where A, ␤, and Aϫ␤ reflect intramyocardial blood volume, red cell velocity, and flow, respectively. During hyperemia alone, LCx probe and microsphere flows and MCE-derived red cell velocity increased from baseline (30Ϯ14 versus 125Ϯ62 mL/min, PϽ0.0005; 1.5Ϯ0.5 versus 6.6Ϯ2.0 mL · min Ϫ1 · g Ϫ1 , PϽ0.0005; and 0.53Ϯ0.14 versus 0.96Ϯ0.45 second

111 Detection of changes in myocardial blood flow and volume: a CMR study in a canine model of coronary artery stenosis

“…As expected, in stenotic dogs, increased MBF values during the hyperemia were proportionally attenuated with the stenosis degrees (negative correlation) in the LAD region ( Figure 4). Interestingly, the flow reserve in the normal region decreased with stenosis severity as well, which agrees with other studies [3][4][5][6]. The same finding was observed in MBV during Dobutamine hyperemia.…”

Fractional flow reserve (FFR)-based therapy in patients presenting with acute coronary syndrome: Current data and everyday practice

“…These processes fundamentally indicate extensive ischemia in adjoining areas of cardiac muscle, vasoconstriction caused by local neurohormonal reactions [35] as well as an increase in the end-diastolic pressure in the left ventricle (LVEDP) [34]. Further studies show that even isolated subendocardial ischemia (which occurs in patients with NSTEMI) can cause an important microvascular dysfunction of the cardiac muscle as a whole [8,[36][37][38][39][40].…”

Coronary Flow Reserve in the Remote Myocardium Predicts Left Ventricular Remodeling Following Acute Myocardial Infarction

“…However, microvascular function has also been reported as impaired even in the remote regions supplied by normal coronary arteries 3. Nevertheless, the clinical significance of microvascular dysfunction in the remote region has not yet been fully examined 4. Microvascular flow in humans is difficult to observe, and the methods of measuring microvascular flow are also very complex.…”