Key result
Tricyclic antidepressants impair cardiac contractility and conduction, with doxepin showing greater negative inotropy.
Why the study?
The cardiac effects of tricyclic antidepressants on myocardial contractile force and conduction were studied to understand their toxicological impact.
Answers are grounded in this paper and cite their sources.
Doxepin depresses contractility more than other TCAs in isolated hearts; hypothesis-generating for differential cardiotoxicity in patients.
The effects of tricyclic antidepressants were studied on the isolated perfused guinea-pig heart simultaneously recording myocardial contractile force and cardiac electrogram. 2. Tricyclic antidepressants in a concentration 4 X 10(-5) mol/1 decreased cardiac contractile force and increased cardiac conduction time. 3. Doxepin had significantly greater negative inotropic effect than nortriptyline, protriptyline, desipramine, amitriptyline and imipramine (P less than 0.01). 4. There was no significant difference in the increase in P-R interval (P less than 0.5) and QRS width (P greater than 0.95) between the tricyclic antidepressants. 5. The isolated perfused guinea-pig heart can be used as a toxicological model for testing and treating cardiac arrhythmias induced by tricyclic antidepressants.
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Dumovic et al. (1977) studied this question. Tricyclic antidepressants was evaluated on Cardiac contractile force and cardiac conduction time (p=<0.01). Tricyclic antidepressants decreased cardiac contractile force and increased conduction time in isolated guinea-pig hearts, with doxepin having a greater negative inotropic effect.
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