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Reflex increase in coronary vascular resistance in patients with ischemic heart disease
Insights
The cold pressor test caused coronary vasoconstriction in patients with coronary artery disease, potentially worsening ischemia. This suggests adrenergically mediated coronary vascular tone plays a role in heart disease.
Area of Science:
- Cardiology
- Vascular Physiology
Background:
- Ischemic heart disease is a leading cause of mortality worldwide.
- Coronary vasoconstriction can exacerbate myocardial ischemia.
Purpose of the Study:
- To investigate coronary vasoconstriction during the cold pressor test (CPT) in patients with coronary artery disease (CAD).
- To explore the role of adrenergic mechanisms in CAD-related coronary vascular tone.
Main Methods:
- Coronary vascular resistance (CVR) was measured in 12 patients with CAD and 12 controls.
- Measurements were taken before and during the CPT, a cold stimulus known to induce systemic vasoconstriction.
- The effect of phentolamine, an adrenergic antagonist, was assessed in some patients.
Main Results:
- CVR increased by 27% in the CAD group during the CPT (P < 0.005), but not in controls.
- Coronary flow decreased in 3/12 CAD patients despite increased arterial pressure.
- Angina symptoms were precipitated in 4/12 CAD patients during the CPT.
- Phentolamine abolished CPT-induced increases in arterial pressure and CVR in CAD patients.
Conclusions:
- Adrenergic stimulation during the CPT induces significant coronary vasoconstriction in patients with CAD.
- This vasoconstriction may compromise coronary blood flow and precipitate angina.
- Adrenergically mediated coronary vascular tone is a crucial factor in the pathophysiology of ischemic heart disease.
Abstract:
To assess possible coronary vasoconstriction in patients with ischemic heart disease, we measured coronary vascular resistance in 12 patients with normal hearts and 12 with coronary disease before and during the initial 50 seconds of cold pressor test, a stimulus known to produce systemic vasoconstriction. Control coronary vascular resistance was similar in the two groups, and although it did not change in patients with normal vessels, it rose by 27 per cent (P less than 0.005) in the group with coronary disease during the cold pressor test. In three of 12 patients with coronary disease coronary flow actually declined despite an increase in arterial pressure; in four, angina was precipitated. Phentolamine abolished increases in arterial pressure and coronary vascular resistance during the test in three patients with coronary disease. Adrenergically mediated coronary vascular tone may be an important determinant of coronary blood flow and may contribute to ischemia in patients with coronary disease.