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Impairment of flow-dependent coronary dilation in hypertensive patients. Demonstration by cold pressor test induced
A Nitenberg1, I Antony, E Aptecar
1Service d'Explorations Fonctionnelles, Centre Hospitalier et Universitaire Xavier Bichat, Paris, France.
Insights
Hypertensive patients with normal-appearing coronary arteries show impaired endothelium-dependent dilation during the cold pressor test, indicating a dysfunction in flow-mediated dilation despite normal angiography.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Endothelial Function
Background:
- Normal coronary arteries dilate with increased flow velocity, a response partly mediated by sympathetic stimulation.
- Arterial hypertension can involve endothelial dysfunction, even in angiographically normal coronary arteries.
Purpose of the Study:
- To evaluate epicardial coronary artery response to cold pressor test-induced flow velocity changes in untreated hypertensive patients with normal coronary arteries.
- To compare flow-mediated dilation between hypertensive patients and healthy controls.
Main Methods:
- Quantitative angiography and Doppler flow testing measured coronary artery diameters and flow velocity during the cold pressor test.
- Evaluated proximal and distal segments of the left anterior descending coronary artery.
- Compared responses to an endothelium-independent dilator.
Main Results:
- Control subjects showed significant dilation (proximal: 12.0%, distal: 13.9%) with increased flow velocity.
- Hypertensive patients exhibited significant constriction (proximal: -10.3%, distal: -7.9%) despite increased flow velocity.
- Endothelium-independent dilation was similar in both groups, suggesting preserved smooth muscle function.
Conclusions:
- Endothelium-dependent, flow-mediated coronary dilation is impaired in hypertensive patients with angiographically normal coronary arteries.
- This impairment occurs even without other major coronary risk factors.
- Suggests early endothelial dysfunction in hypertension affecting coronary reactivity.
Abstract:
In normal coronary arteries, increased flow velocity induces endothelium-dependent dilation, and dilation in response to sympathetic stimulation evoked by the cold pressor test is partly due to increased flow velocity. In arterial hypertension, angiographically normal coronary arteries were constricted by acetylcholine, an endothelium-dependent vasodilator. To assess the epicardial coronary artery response to the increase blood flow velocity induced by the cold pressor test in hypertensive patients with angiographically normal coronary arteries, coronary artery diameters and flow velocity were measured during cold pressor test in 12 untreated hypertensive patients and in 10 control subjects. Diameters were determined by quantitative angiography on proximal and distal segments of the left anterior descending coronary artery, and flow velocity measurements were made by Doppler testing in the distal segment. In control subjects, the proximal and distal segments dilated during cold pressor test by 12.0 +/- 4.5% and 13.9 +/- 6.5%, respectively (both P < .001), when flow velocity increased by 46.7 +/- 26.1% (P > .05). In hypertensive patients, segments were constricted, respectively, by 10.3 +/- 8.5% (P < .001) and 7.9 +/- 8.6% (P < .01), when the flow velocity was increased by 68.3 +/- 48.2% (P < .001). Intracoronary injection of an endothelium-independent dilator resulted in similar dilation in control subjects (proximal: +30.0 +/- 12.9%; distal: +32.4 +/- 15.2%) and in hypertensive patients (proximal: +22.3 +/- 7.5%; distal: +28.8 +/- 15.4%). In conclusion, in hypertensive patients with angiographically normal coronary arteries and without any other coronary risk factors, endothelium-dependent flow-mediated coronary dilation evoked by the cold pressor test is impaired.(ABSTRACT TRUNCATED AT 250 WORDS)