Ca++ channel-blocking drugs in shock and trauma: new approaches to old problems?

The development of drugs that inhibit Ca++ influx through voltage-regulated cell membrane channels of excitable cells represents a new pharmacodynamic addition to the therapy of cardiovascular disorders. These drugs, the Ca++ channel-blocking agents, have important therapeutic roles in the management of exertional and variant angina and also in the treatment of certain types of supraventricular tachyarrhythmias. In addition, a rapidly expanding body of evidence indicates that these compounds also may exert beneficial actions in various other cardiovascular-related disorders, including different forms of shock and trauma. Theoretically, beneficial effects of Ca++ channel blockade may be explained by either a direct reduction of pathologic Ca++ overload in injured cells or, indirectly, by vasodilation and hemodynamic improvement in tissue perfusion-oxygen demand relationships. Many questions remain unanswered, however, and recent experimental studies have questioned the routine use of these drugs in shock or trauma. Furthermore, the propensity for hypotensive and cardiodepressant actions of Ca++ channel blockade may well be enhanced in patients with preexisting or occult loss of myocardial contractile reserves. These complexities should be assessed carefully before Ca++ channel-blocking drugs are used in the treatment of shock states.