Hemodynamic, electrocardiographic, and cellular effects of diltiazem treatment after cardiac arrest and resuscitation

Safety and efficacy of intravenous diltiazem in atrial fibrillation or atrial flutter

This study examines the efficacy of various doses of intravenous diltiazem to control the ventricular response during atrial fibrillation or atrial flutter. Control of the ventricular response of patients with atrial fibrillation and a rapid ventricular response can provide patients with relief of symptoms and improve hemodynamics. Eighty-four consecutive patients with atrial fibrillation or atrial flutter, or both, received an intravenous bolus dose of diltiazem followed by a continuous infusion of diltiazem at 5, 10, and 15 mg/hour. The mean ventricular response and blood pressure were monitored. Overall, 94% of patients (79 of 84) responded to the bolus dose with a > 20% reduction in heart rate from baseline, a conversion to sinus rhythm, or a heart rate < 100 beats/min. Seventy-eight patients received the continuous infusion. After 10 hours of infusion, 47% of patients (confidence interval [CI]: 36%, 59%) had maintained response with the 5 mg/hour infusion, 68% (CI: 57%, 79%) maintained response after the infusion was titrated to 10 mg/hour, and 76% (CI: 66%, 85%) after titration from the 5 and 10 mg/hour infusion to the 15 mg/hour dose. For the 3 diltiazem infusions studied, mean (+/- SD) heart rate was reduced from a baseline value of 144 +/- 14 beats/min to 98 +/- 19, 107 +/- 25, 107 +/- 22, 101 +/- 22, 91 +/- 17, and 88 +/- 18 beats/min at infusion times 0, 1, 2, 4, 8, and 10 hours, respectively. By the end of the infusion, 18% of patients (14 of 78) had conversion to sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Nimodipine after circulatory arrest: effects on oxygen delivery and consumption

PURPOSE

Evaluation of the effects of nimodipine administration during and after cardiopulmonary resuscitation (CPR) on oxygen delivery and consumption was the aim of this study.

METHODS

A randomized double-blind study in 32 anesthetized domestic pigs was performed. After 5 minutes of ventricular fibrillation (VF) and 5 minutes of external CPR, epinephrine (50 micrograms/kg) and either nimodipine or placebo (10 micrograms/kg bolus, 1 microgram/kg/min continuously throughout 4 hours of observation) were administered. One minute later (equal to 11 minutes VF), the first countershock was given. If this failed to restore spontaneous circulation, epinephrine and countershocks were repeated for a maximum of 30 minutes.

RESULTS

Eleven of 12 nimodipine- and 7 of 14 placebo-treated pigs could be resuscitated successfully and survived the observation period (P < .05). Hemodynamic responses to nimodipine were characterized by significant decreases in systemic vascular resistance and mean arterial pressure from 10 minutes after restoration of spontaneous circulation onwards with consequent significant increases in cardiac output. Median systemic oxygen delivery indices (DO2I) in nimodipine-treated pigs were significantly higher at all measuring points when compared with placebo-treated animals. Median systemic oxygen consumption indices (VO2I) did not differ significantly between groups. Median oxygen extraction ratios in nimodipine-treated pigs were in the same range as prearrest and were lower when compared with placebo-treated pigs (at 30 minutes P < .05 and at 120 minutes P < .01). DO2I and VO2I were poorly correlated in all pigs treated with nimodipine and in 3 of 7 animals treated with placebo, suggesting supply independency in these animals. This difference between groups was significant (P < .05).

CONCLUSIONS

Our findings suggest that in nimodipine-treated animals, a lower oxygen deficit or a better redistribution of regional blood flow occurred after circulatory arrest and resuscitation.