Transcutaneous pacing in a hypothermic-dog model.

Abstract

To evaluate the hemodynamic response to transcutaneous pacing (TCP) during rewarming from hypothermia. We conducted a prospective, controlled laboratory investigation using 20 mongrel dogs. The animals were anesthetized, intubated, and mechanically ventilated. Arterial pressure, core temperature, and cardiac rhythm were continuously monitored. All dogs were cooled to a core temperature of 27 degrees C; experimental animals were then subjected to TCP with active rewarming, and control animals underwent sham transcutaneous pacing and rewarmed in the same manner. Serial hemodynamic measurements, time to rewarming, and cardiac isoenzyme concentrations were analyzed. Rewarming was accomplished significantly faster in the paced group (171.5 +/- 31.5 minutes) than in the control group (254 +/- 55.9 minutes, P < .05). After rewarming, the mean cardiac index in the paced dogs returned to 84% of baseline, compared with 63% of baseline in the nonpaced group (P < .05). None of the paced animals demonstrated significant hemodynamic deterioration, potentially lethal arrhythmias, or other evidence of myocardial injury. TCP is safe, effective and easily implemented in dogs. In this small series of dogs, TCP restored and maintained hemodynamic stability and allowed the hypothermic animals to rewarm in half the time required by their nonpaced counterparts.