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Hemodynamic effects of intravenous timolol in coronary artery disease
Abstract:
The hemodynamic effects of intravenous timolol were evaluated in 20 patients with coronary artery disease during diagnostic cardiac catheterization. The threshold dose of 0.25 mg reduced heart rate and cardiac index by 15% (p less than 0.05), left ventricular work index by 21% (p less than 0.05), and left ventricular dp/dt by 16% (p less than 0.05) while increasing left ventricular end-diastolic pressure by 49% (p less than 0.01), mean pulmonary arterial pressure by 17% (p less than 0.01), and systemic vascular resistance by 16% (NS). Larger doses (0.5 mg and 1.0 mg) induced similar responses with a greater effect on systemic vascular resistance (+22%, p less than 0.01, and +31%, p less than 0.001). The mean arterial pressure and stroke volumes were not affected by timolol. Peak effects, occurring at about 10 min after drug injection, did not correlate with plasma levels. The overall hemodynamic effects of timolol were similar to those reported for equipotent doses of propranolol and could be accounted for by the beta-adrenoceptor blocking activity.
Insights
Intravenous timolol significantly impacts hemodynamics in coronary artery disease patients. This beta-blocker reduces cardiac workload and heart rate, but increases filling pressures and vascular resistance.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Coronary artery disease (CAD) requires careful management of cardiac function.
- Understanding the hemodynamic effects of beta-blockers like timolol is crucial for patient care.
Purpose of the Study:
- To evaluate the hemodynamic effects of intravenous timolol in patients with coronary artery disease.
- To compare the effects of different timolol doses on cardiovascular parameters.
Main Methods:
- Twenty patients with CAD underwent diagnostic cardiac catheterization.
- Intravenous timolol was administered at doses of 0.25 mg, 0.5 mg, and 1.0 mg.
- Hemodynamic parameters including heart rate, cardiac index, ventricular pressures, and vascular resistance were measured.
Main Results:
- A 0.25 mg dose of timolol reduced heart rate and cardiac index by 15%, left ventricular work index by 21%, and left ventricular dp/dt by 16%.
- Timolol increased left ventricular end-diastolic pressure by 49% and mean pulmonary arterial pressure by 17%.
- Higher doses amplified the increase in systemic vascular resistance, while mean arterial pressure and stroke volumes remained unaffected.
Conclusions:
- Intravenous timolol exerts significant hemodynamic effects in CAD patients, primarily through beta-adrenoceptor blockade.
- The observed effects are comparable to those of propranolol at equipotent doses.
- Timolol's impact on cardiac workload and vascular resistance warrants consideration in clinical settings.