Wie funktioniert und wie wirkt die biphasische defibrillation

No therapeutic approach other than transthoracic external cardioversion (C) or defibrillation (D) is the method of choice in emergencies in patients (pts) with ventricular fibrillation (VF) or hemodynamic unstable ventricular tachycardia (VT). This intervention can be necessary in patients (pts) with atrial fibrillation (AF) and rapid ventricular response or in pts with permanent AF for elective cardioversion. Three different waveforms were used for C or D: "monophasic" (M), "biphasic" (B) or "triphasic" (T) impulses. It has been shown in animal as well as in clinical studies that application of B-shocks (S) used for external D is associated with a higher efficacy rate compared to M-S. In addition, biphasic waveforms are associated with less injurious effects on hemodynamic performance and myocardial metabolism. Initial results demonstrated that B-S using automatic external defibrillators (AED) defibrillated pts at higher rates compared to M-S. It has been well known for many years that in pts with implantable defibrillators (ICD) B-S will lead to lower defibrillation thresholds (DFT) and a higher success of initial defibrillation compared to ICDs with M-S. T-S are better than M-S in ICDs but there is no advantage of T-S compared to B-S, and, therefore, there is no place for T-S in clinical cardiology. It seems that external transthoracic C for acute or elective termination of atrial fibrillation has higher success rates when B-S were used compared to the application of M-S. Therefore, C with B-S should be performed in all pts with AF before undertaking transcatheter internal cardioversion procedures. In conclusion, the availibity of B-S yields to a new unterstanding of C and D; biphasic impulses are the waveforms of choice in pts with VT/VF, in pts with fast AF or pts with AF who need elective C. In all pts, B-S should be applied when M-S are unsuccessful or as a first choice when B-S are available.