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Effects of amitriptyline on left ventricular function in conscious dogs
Journal of Cardiovascular Pharmacology
|November 1, 1981
Summary
Amitriptyline, a common antidepressant, moderately depresses heart muscle contractility. This effect is worsened by propranolol, suggesting potential cardiac risks in patients with existing heart conditions.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- Amitriptyline (Am) is a widely used tricyclic antidepressant.
- Am is linked to sudden cardiac death, suspected to be arrhythmia-related.
- Its effects on left ventricular function are not well understood.
Purpose of the Study:
- To investigate the impact of intravenous Amitriptyline on left ventricular function in conscious dogs.
- To assess the influence of propranolol on Amitriptyline's cardiac effects.
Main Methods:
- Conscious, instrumented dogs received intravenous Amitriptyline (0.5, 1.0, 1.5 mg/kg).
- Measurements included heart rate (HR), left ventricular end diastolic pressure (LVEDP), mean arterial pressure (MAP), and the maximum rate of rise of left ventricular pressure (dP/dtmax).
- Experiments were conducted both with and without propranolol administration.
Main Results:
- Amitriptyline increased HR significantly (up to 70%), an effect partially blocked by propranolol.
- Left ventricular end diastolic pressure decreased without propranolol but not with it.
- Myocardial contractility, indicated by dP/dtmax, moderately decreased (14-29%) with Am, an effect exacerbated by propranolol.
Conclusions:
- Intravenous Amitriptyline, at therapeutic levels, depresses myocardial contractility.
- Propranolol accentuates Amitriptyline's negative inotropic effects.
- Tricyclic antidepressants may adversely affect cardiac performance in patients with underlying myocardial dysfunction.