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Effects of selective and non-selective beta-adrenergic blockade on coronary dynamics in man assessed by rapid atrial
Insights
Propranolol and atenolol do not significantly constrict coronary arteries. Cardioselectivity of beta-blockers is unimportant for coronary circulation effects.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Beta-adrenergic blockade is used to manage cardiovascular conditions.
- The impact of beta-blockers on coronary dynamics requires further elucidation.
Purpose of the Study:
- To investigate the effects of propranolol and atenolol on coronary dynamics.
- To determine if cardioselectivity influences beta-blocker effects on the coronary circulation.
Main Methods:
- Studied 12 patients with suspected coronary artery disease undergoing cardiac catheterization.
- Measured myocardial blood flow using coronary sinus continuous thermodilution.
- Assessed drug effects immediately post-administration and during rapid atrial pacing.
Main Results:
- Both propranolol and atenolol reduced heart rate and myocardial oxygen consumption similarly.
- Coronary sinus flow changes during pacing correlated with tension-time index.
- This relationship remained unaltered by either drug, indicating no significant coronary vasoconstriction.
Conclusions:
- Neither propranolol nor atenolol possess significant coronary vasoconstrictor properties.
- Cardioselectivity does not appear to be a critical factor in the beta-adrenergic blockade of the coronary circulation.
Abstract:
The effects on coronary dynamics of propranolol and atenolol were studied in 12 patients undergoing cardiac catheterisation for suspected coronary artery disease. Myocardial blood flow was measured using the coronary sinus continuous thermodilution technique. Data were obtained immediately after drug administration and during rapid atrial pacing. The immediate effects were similar for both drugs. A significant reduction in heart rate was accompanied by a small reduction in myocardial oxygen consumption. Changes in coronary sinus flow induced by rapid pacing were closely related to changes in tension-time index. This relation was not modified by propranolol or atenolol. Neither propranolol nor atenolol therefore has significant coronary vasoconstrictor properties. Cardioselectivity appears to be unimportant with respect to beta-adrenergic blockade and the coronary circulation.