21 - Analysis and predictive value of the ventricular fibrillation waveform

Summary

Introduction: Why analyze the waveform?

Ventricular fibrillation (VF) is the cardiac arrest rhythm most amenable to successful treatment, and the vast majority of survivors from human cardiac arrest have VF as their primary rhythm. Successful treatment in these patients almost invariably requires electrical defibrillation. While advances have been made in defibrillation therapy, particularly in the introduction of automatic and semi-automatic defibrillators (AED) with rhythm recognition and the use of novel defibrillatory waveforms, the primary determinant of successful defibrillation is the duration of the VF episode. With the passage of time, the chances of successful defibrillation fall dramatically. Basic life support (BLS) procedures in general and myocardial perfusion due to closed-chest compression can only retard the metabolic deterioration of the myocardium. With prolonged duration of VF, an increasing likelihood of asystole, pulseless electrical activity, or persistent VF following countershock results. Moreover, multiple countershocks that do not result in spontaneous circulation are probably harmful by causing thermal damage to the heart and increasing cumulative defibrillation energy decreases postresuscitation myocardial function and survival.

For these reasons, researchers attempt to interrogate the VF waveform determined from the surface electrocardiogram (ECG) trace to ascertain knowledge of the myocardial state, to assess the probability of success of a defibrillating shock, and to investigate whether, by physical or pharmacological means, the situation can be changed to improve the likelihood of restoring a spontaneous perfusing rhythm.

Data acquisition and preprocessing

Logistic difficulties

Although the primary focus of analysis is the ECG-derived VF waveform itself, additional documentation such as patient demographics, electrical, pharmacological, and physical interventions, and outcome information is required to provide meaningful conclusions.