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Intracoronary Acetylcholine Provocation Testing for Assessment of Coronary Vasomotor Disorders
Published on: August 18, 2016
Response of normal and diseased epicardial coronary arteries to vasoactive drugs: quantitative arteriographic studies
Insights
Nitroglycerin effectively dilates coronary arteries, while verapamil and diltiazem show minimal effects. Isometric handgrip constricts coronary arteries, leading to ischemia, which nitroglycerin can prevent.
Area of Science:
- Cardiology
- Pharmacology
- Physiology
Background:
- Coronary vasodilators are crucial for managing angina.
- Understanding drug effects on coronary arteries during stress is vital.
Purpose of the Study:
- To evaluate the efficacy of nitroglycerin, verapamil, and diltiazem in dilating coronary arteries.
- To assess the impact of isometric handgrip stress on coronary hemodynamics and left ventricular function.
Main Methods:
- 93 patients undergoing cardiac catheterization were studied.
- Ischemia was induced via isometric handgrip or ergonovine maleate.
- Hemodynamic and angiographic changes were measured with and without vasodilator administration (nitroglycerin, verapamil, diltiazem).
Main Results:
- Nitroglycerin significantly increased luminal area in normal (28%) and stenotic (29%) coronary arteries.
- Verapamil (9%) and diltiazem (4%) showed minimal epicardial coronary dilation; diltiazem did not dilate stenoses.
- Isometric handgrip constricted coronary arteries (20-22%) and increased pulmonary wedge pressure (56%) in stenotic segments, causing ischemia.
- Intracoronary nitroglycerin prevented handgrip-induced coronary constriction and left ventricular dysfunction without altering systemic hemodynamics.
Conclusions:
- Nitroglycerin is a potent coronary vasodilator, effective in both normal and stenotic arteries.
- Verapamil and diltiazem have limited efficacy in dilating epicardial coronary arteries and stenoses.
- Isometric handgrip induces coronary constriction and ischemia, which can be mitigated by nitroglycerin, preserving left ventricular function.
Abstract:
Coronary vasodilators known to be effective in effort and vasospastic angina were studied in 93 patients undergoing catheterization for evaluation of chest pain. The ischemia-provoking stresses were isometric handgrip (25% of maximum for 4 to 5 minutes) or ergonovine maleate (0.2 mg intravenously). Hemodynamic changes and changes in angiographic diameter of epicardial coronary arteries were measured during these stresses, with and without drug administration. Drugs included intravenous diltiazem (0.25 mg/kg load + 0.003 mg/kg/min), intravenous verapamil (0.14 mg/kg load + 0.0075 mg/kg/min) and intracoronary (0.012 mg/min X 4 minutes) and sublingual (0.4 mg) nitroglycerin. From these studies, the following statistically valid conclusions were reached. First, nitroglycerin is a potent dilator of epicardial coronary arteries, increasing normal luminal area an average of 28% and luminal area in significantly stenotic segments by 29%. Second, verapamil and diltiazem are nonsignificant epicardial coronary dilators (9% and 4% luminal area increase, respectively). Similarly, diltiazem does not dilate significant coronary stenoses. Third, sustained isometric handgrip increases systemic blood pressure and heart rate by reflex activation of the sympathetic nervous system. By this means, handgrip also constricts luminal area in normal and diseased coronary segments by 20% and 22%, respectively. One result of these changes is a handgrip-induced, ischemic 56% rise in pulmonary wedge pressure in patients with significant stenosis. Fourth, intracoronary nitroglycerin, in very small doses, does not block the systemic hemodynamic response to handgrip, but prevents handgrip-induced coronary constriction and the associated ischemic left ventricular dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
