A method of performing transthoracic defibrillation is described. The method includes generating at least two different defibrillation waveforms using at least two different defibrillation circuits contained in separate housings, delivering each of the at least two different defibrillation waveforms across a respective electrical path of a plurality of electrical paths established across the thoracic cavity and through the heart of a patient by at least three electrodes attached to the thorax of the patient, and synchronizing delivery of the at least two different defibrillation waveforms with communications between the separate housings.