CARDIOVASCULAR EFFECTS OF POISONING WITH TRICYCLIC ANTIDEPRESSANTS

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Abstract
Cardiovascular dynamics have been studied in 10 patients admitted because of poisoning by tricyclic antidepressants (TCA) and in 7 with hypnotic drug (HD) poisoning. Right heart catheterization (floating catheter technique) and determination of cardiac output (dye dilution technique) have been performed during and after an initial comatous phase. In the TCA group there were marked ECG changes with a mean increase of QRS duration to 0.14 sec during the comatous phase. The cardiac output was then increased in relation to the calculated oxygen uptake compared with the findings in awake state, when the ECG changes had diminished or disappeared. After i.v. administration of 5 mg propranolol the fall in cardiac output was most pronounced during the comatous phase but the broadening of QRS complexes was not affected. The central venous and systemic arterial BP were normal. As judged by the normal diastolic pressure in the pulmonary artery and the normal central venous pressure there were no signs of myocardial insufficiency. The cardiac output in the TCA group was twice as high, i.e. significantly higher, as in the HD patients. The arteriovenous oxygen difference was significantly lower (on an average 40%). The hyperkinetic circulation during TCA poisoning may be explained by a dominant adrenergic stimulatory effect on the circulation.