Abstract 73: Changes in AMSA During Controlled Coronary Perfusion by Extracorporeal Circulation in a Swine Model of Ventricular Fibrillation
Background: Previous VF studies in rats showed that 6 min of CPR was needed before an electrical shock could be successful in reestablishing cardiac activity. During this interval the amplitude spectral area (AMSA) - a method of VF waveform analysis - progressively rose reaching a plateau within the same interval required for enabling successful defibrillation. No previous studies have examined AMSA continuously using a model of tightly controlled CPR.
Methods: VF was induced and left untreated for 8 min in 16 swine after which extracorporeal circulation (ECC) was maintained for 10 min adjusting its flow to generate a coronary perfusion pressure of 10 mmHg. AMSA was calculated from the VF signal in the frequency domain within 2-48 Hz and analyzed continuously with a 2.1 s timeframe and a Tukey window that moved ahead every 0.5 s.
Results: AMSA progressively declined during untreated VF. During ECC, AMSA rose from 6.8±1.9 to 12.4±4.1 mV*Hz (p<0.001). The increase occurred early during ECC and plateaued after 4 to 6 minutes (Figure). Individual experiments showed distinct and varying AMSA patterns during ECC. The average peak AMSA was reached 368 ± 127 s after the start of ECC.
Conclusion: The time course of AMSA varied among animals suggesting variability in the time required for the myocardium to reach the optimal conditions for successful defibrillation and highlights the value of continuous monitoring of AMSA during CPR.
- © 2013 by American Heart Association, Inc.