Diltiazem to treat sinus tachycardia in critically ill patients: A four-year experience

Objectives., To determine whether an intravenous infusion of the calcium ch annel blocker diltiazem was effective and safe in treating sinus tachycardi a in critically ill adult patients with contraindications to beta -blockers or in whom beta -blockers were ineffective. Design. Retrospective chart review. Setting. University medical center. Patients. The records of 171 surgical intensive care unit patients with sin us tachycardia treated with intravenous diltiazem were evaluated. Interventions. In all patients with sinus tachycardia (heart rate > 100 bea ts/min), heart rate control with intravenous diltiazem was attempted after adequate intravascular volume expansion, pain, and anxiety control. In all patients, beta -blockade either was contraindicated or (in 7%) had failed. Intravenous diltiazem was administered as a slow 10-mg bolus dose (0.1-0.2 mg/kg ideal body weight), and then an infusion was started at 5 or 10 mg/hr and increased up to 30 mg/hr, as needed, to decrease heart rate to < 100 b eats/min. Variables retrospectively collected included demographic data, pr einfusion blood pressure, mean arterial pressure, heart rate, and preinfusi on pressure-rate quotients (pressure-rate quotient = mean arterial pressure divided by heart rate). Intravenous bolus dose, when given, and diltiazem infusion rate and time necessary to achieve the target heart rate also were recorded. The lowest heart rate recorded within 24 hrs from the initiation of the infusion and the time necessary to achieve the lowest heart rate af ter beginning the infusion were recorded. Measurements and Results. Of 171 patients studied, 97 (56%) were classified as responders. Multiple linear regression suggested that response could be predicted by age, pressure-rate quotients, baseline mean arterial pressure , and central nervous system failure. In the responders, a heart rate <100 beats/min was achieved in an average of 2 hrs, at a mean diltiazem infusion of 13.3 mg/hr. The lowest rate reached by the responders in a 24-hr period averaged 86 beats/min and was achieved in 4.8 hrs with a mean infusion rat e of 14.8 mg/hr. Both target and lowest rate values were statistically diff erent from baseline heart rate. Conclusion. Diltiazem was effective in achieving short-term control of hear t rate in 56% of the patients, virtually without adverse effects, where P-b lockade was contraindicated or ineffective.