Glover Benedict M, McCann Conor J, Manoharan Ganesh, Walsh Simon J, Moore Michael J, Allen James D, Escalona Omar, Anderson John McC, Trouton Tom G, Stevenson Mike, Roberts Michael J, Adgey Jennifer Aa
Regional Medical Cardiology Center, Royal Victoria Hospital, Belfast, Northern Ireland.
Pacing Clin Electrophysiol. 2008 Aug;31(8):1020-4. doi: 10.1111/j.1540-8159.2008.01129.x.
The optimal waveform tilt for defibrillation is not known. Most modern defibrillators used for the cardioversion of atrial fibrillation (AF) employ high-tilt, capacitor-based biphasic waveforms.
We have developed a low-tilt biphasic waveform for defibrillation. This low-tilt waveform was compared with a conventional waveform of equivalent duration and voltage in patients with AF. Patients with persistent AF or AF induced during a routine electrophysiology study (EPS) were randomized to receive either the low-tilt waveform or a conventional waveform. Defibrillation electrodes were positioned in the right atrial appendage and distal coronary sinus. Phase 1 peak voltage was increased in a stepwise progression from 50 V to 300V. Shock success was defined as return of sinus rhythm for >/=30 seconds.
The low-tilt waveform produced successful termination of persistent AF at a mean voltage of 223 V (8.2 J) versus 270 V (6.7 J) with the conventional waveform (P = 0.002 for voltage, P = ns for energy). In patients with induced AF the mean voltage for the low-tilt waveform was 91V (1.6 J) and for the conventional waveform was 158 V (2.0 J) (P = 0.005 for voltage, P = ns for energy). The waveform was much more successful at very low voltages (less than or equal to 100 V) compared with the conventional waveform (Novel: 82% vs Conventional 22%, P = 0.008).
The low-tilt biphasic waveform was more successful for the internal cardioversion of both persistent and induced AF in patients (in terms of leading edge voltage).
