Atrial function during cardiac arrest caused by ventricular fibrillation

Objectives: To report observations on preserved regular atrial electrical and mechanical systole during ventricular fibrillation (VF) and to quantitate blood flow generated by atrial contractions in this setting. Methods: In 10 rats, light atrial pressure pulses were continuously recorded before and for An interval of 8 min after inducing VF. In 3 isolated, pcr fused rat hearts, epicardial right atrial electrograms were recorded after inducing VF, In 15 pigs, transesophageal echo-Doppler measurements were obtained with pulsed and color-Doppler visualization of flow across the mitral valve after onset of VF. Results: In each rat, regular right atrial pressure pulses were documented during VF. These persisted over an average internal of 7.5 min. Ill isolated, perfused Ileal ts, right atrial contractions were accompanied by regular atrial depolarizations. In pigs, regular atrial contractions generated atrial stroke volumes of approximately 12 mt, or 25% of prearrest values during the first minute after onset of VF, but those declined to approximately 6 mt after 10 mill of untreated cardiac al I est. Blood flow from the left atrium into the left ventricle failed to advance significantly into the systemic circuit. During atrial diastole, we observed reversal of flow into the left atrium, Conclusions: Atrial contractions are preserved during the initial 8 min or more after cardiac al lest due to VF, Substantial forward now into the left ventricle failed to advance through the outflow tract but regurgitated into the atrium during atrial diastole.