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Reduced epicardial coronary vasodilator capacity in patients with left ventricular hypertrophy
G Vassalli1, P Kaufmann, B Villari
1Department of Internal Medicine, University Hospital, Zurich, Switzerland.
Insights
In left ventricular hypertrophy (LVH), coronary arteries enlarge but show reduced vasodilator capacity. Nitroglycerin sensitivity remains normal, suggesting flow-mediated changes or vascular remodeling contribute to impaired coronary function.
Area of Science:
- Cardiovascular Physiology
- Cardiac Adaptation
- Coronary Vasomotor Regulation
Background:
- Epicardial coronary artery enlargement is an adaptive response to increased blood flow in left ventricular (LV) hypertrophy.
- Understanding the functional implications of this adaptation is crucial for managing cardiac conditions.
Purpose of the Study:
- To investigate the vasodilator capacity of epicardial coronary arteries in patients with left ventricular hypertrophy.
- To assess the impact of LV hypertrophy on coronary artery response to nitroglycerin.
Main Methods:
- Quantitative coronary angiography was used to assess nitroglycerin-induced vasodilation in patients with aortic stenosis and valvular heart disease.
- Coronary artery dimensions and responses to intracoronary nitroglycerin were measured in patients with LV hypertrophy and control subjects.
Main Results:
- Patients with aortic stenosis showed reduced vasodilator capacity compared to controls, despite similar nitroglycerin sensitivity.
- In LV hypertrophy, coronary arteries were larger at baseline and exhibited significantly blunted dilation in response to nitroglycerin (6% increase vs. 21% in controls).
- A significant inverse correlation was observed between baseline coronary artery length and its percent increase after nitroglycerin.
Conclusions:
- Epicardial coronary arteries in LV hypertrophy have reduced vasodilator capacity, though nitroglycerin sensitivity is preserved.
- Impaired coronary vasodilation may result from flow-mediated alterations in vasomotor tone or vascular remodeling, including arterial enlargement.
Background:
Enlargement of the epicardial coronary arteries occurs in left ventricular (LV) hypertrophy as an adaptation to the increased coronary blood flow.
Methods And Results:
Vasodilator capacity of the epicardial coronary arteries was determined in 44 patients. The dose-response relation of intracoronary nitroglycerin was assessed in 14 patients (7 control subjects and 7 patients with aortic stenosis [study A]) using quantitative coronary angiography. In a second study (B), vasodilator capacity of the epicardial coronary arteries was determined in 15 control subjects and 15 patients with valvular heart disease. In study A, a curvilinear dose-response relation with maximal vasodilation after 90 micrograms intracoronary nitroglycerin was found in both control subjects and patients with aortic stenosis. Vasodilator capacity was reduced in those with aortic stenosis, although sensitivity to nitroglycerin was similar in both groups. In study B, coronary circumferential length at baseline was larger in those with LV hypertrophy (12.2 +/- 2.2 mm) than in control subjects (8.6 +/- 1.5 mm; P < .001); after 100 micrograms intracoronary nitroglycerin, it increased to 12.9 +/- 2.2 mm (6 +/- 5%) in those with LV hypertrophy and to 10.3 +/- 1.5 mm (21 +/- 8%; P < .001) in control subjects. An inverse relation between baseline circumferential length and its percent increase after nitroglycerin was found (r = -.71, P < .001).
Conclusions:
Vasodilator capacity of the epicardial coronary arteries is reduced in patients with LV hypertrophy, although sensitivity to nitroglycerin is normal. This may be due to a flow-mediated decrease in coronary vasomotor tone and/or the occurrence of vascular remodeling with an enlargement of the coronary arteries.