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Burst Stimulation Improves Hemodynamics During Resuscitation After Prolonged Ventricular Fibrillation

From the University of Alabama at Birmingham, Birmingham, Ala.

Correspondence to Gregory P. Walcott, B140 Volker Hall, 1670 University Blvd, Birmingham, AL. E-mail gpw{at}crml.uab.edu

Received June 17, 2008; accepted November 20, 2008.

Background— Although return of spontaneous circulation is frequently achieved during resuscitation for sudden cardiac arrest, systolic blood pressure can then decrease, requiring additional myocardial support. Previous studies have shown that a series of 1-ms electric pulses delivered through the defibrillation patches during ventricular fibrillation can stimulate the autonomic nervous system to increase myocardial function after defibrillation. We hypothesized that a similar series of electric pulses could increase myocardial function and blood pressure during the early postresuscitation period.

Methods and Results— Six swine were studied that underwent 6 to 7 minutes of fibrillation. Each animal received 5, 10, 15, or 20 pulse packets consisting of six 10-A, 1-ms pulses every 3 to 4 s in random order whenever systolic blood pressure became <50 mm Hg. All 4 sets of pulse packets were delivered to each animal. Systolic blood pressure and cardiac function (left ventricular+dP/dt) were increased to above prestimulation levels or above by all 4 sets of pulse packets. The increases were significantly greater for the longer than the shorter number of pulse packets. The mean±SD duration of the time that the systolic pressure remained above 50 mm Hg after pulse delivery was 4.2±2.5 minutes.

Conclusions— Electric stimulation during regular rhythm after prolonged ventricular fibrillation and resuscitation can increase blood pressure and cardiac function to above prestimulation levels.

Key Words: ventricular fibrillation • resuscitation • electric stimulation