Ketamine is known to have direct myocardial depressant effects. What is the mechanism of this depression?
A. Ketamine is a perfect drug. There are no side effects.
B. Inhibition of L-type calcium channels
C. Inhibition of fast type sodium channels
D. Suppression of intracardiac conduction at the sinus and atrial nodes
E. Upregulation of T-type calcium channels
The answer is B. There is no perfect drug. Except Xenon. And honestly, who can even get that stuff. Although ketamine is known for its cardiovascular stability, its effect is mainly through increases in sympathetic stimulation and increases in SVR. In-vitro studies have shown a direct myocardial depressant effect in animal models and the failing adult heart. This is considered to be the result of inhibition of L-type voltage-dependent calcium channels in the sarcolemmal membrane and may be a consideration in critically ill infants (read depletion of sympathetics) with severely impaired cardiac reserves.