Why the study?
Do beta-blocking agents affect coronary vasomotor tone and luminal diameter in large epicardial coronary arteries?
Do beta-blocking agents affect coronary vasomotor tone and luminal diameter in large epicardial coronary arteries?
Standard beta-blockers like propranolol and atenolol induce vasoconstriction in large epicardial coronary arteries, an effect not observed with vasodilatory beta-blockers such as celiprolol.
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Traditional beta-blockers may constrict epicardial coronaries unlike celiprolol; leaves open effects on perfusion and clinical outcomes.
Changes in coronary vasomotor tone of large epicardial coronary arteries today can be assessed quite accurately by exact measurements of coronary diameters applying computer assisted systems. The effect of various vasodilators (nitrates, calcium antagonists, EDRF-dependent compounds) was tested in this way. It appears that normal coronary artery segments reach a maximum of dilator reserve with an increase of luminal diameter of approximately 30-40%; different patterns of kinetics were, however, encountered. beta-Blocking agents, both non-selective (propranolol) and selective (atenolol), were found to lead to a gradual vasoconstriction, i.e., a decrease in diameter by approximately 20-25% over 20 min, an effect which is overcome by nitrates. New beta-blocking compounds with vasodilator properties, such as celiprolol, show no constriction. The vasoconstrictor effect of propranolol and atenolol may not only be due to the decrease of flow following the drop in myocardial oxygen consumption, but could also reflect an unopposed alpha-adrenergic tone. The clinical aspects of this observation are discussed.
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Lichtlen et al. (1991) studied this question.
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