Abstract
We examined the effects of diltiazem on transmural myocardial blood in the presence of a flow-limiting stenosis and during acute total coronary artery occlusion in awake, chronically instrumented dogs. Regional myocardial perfusion was estimated with left atrial injections of 15-μ-diameter radionuclide-labeled microspheres. An electromagnetic flowmeter probe and hydraulic occluder were used to monitor blood flow and produce total and subtotal occlusions of the left circumflex coronary artery. A 10-second total arterial occlusion produced intense coronary vasodilation and a pronounced reactive hyperemic response. When a proximal coronary stenosis prevented reactive hyperemia, ischemic coronary vasodilation after a 10-second arterial occlusion caused transmural redistribution of blood flow toward the subepicardium, resulting in subendocardial underperfusion despite a normal net volume of arterial flow. Although diltiazem did not increase coronary collateral flow during acute arterial occlusion, it did blunt the vasodilation that occurred in response to a 10-second total coronary occlusion, and partially corrected the subendocardial underperfusion that occurred with a proximal flow-limiting coronary stenosis.
Original language | English (US) |
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Pages (from-to) | I-19-I-26 |
Journal | Circulation |
Volume | 65 |
Issue number | 1 II |
State | Published - 1982 |