An apparatus and method for treating post-defibrillation electromechanical dissociation ("EMD") or pulseless electrical activity ("PEA"). A first embodiment comprises an implantable defibrillator with the capability of detecting and treating post defibrillation EMD. The stimulator/defibrillator has one or more leads with electrodes and at least one electrode for defibrillation. A sense circuit senses the electrical condition of the heart of the patient. A second sensor senses a parameter correlated to the state of blood flow. The cardiac stimulator/defibrillator detects and terminates ventricular tachyarrhythmia or fibrillation. If the stimulator/defibrillator detects the presence of electrical rhythm in the heart correlated, however, with inadequate blood flow to sustain life (EMD), the device provides an output to stimulate the heart to overcome EMD. The device may also be an external defibrillator. The method for treating the heart to restore blood flow where electromechanical dissociation occurs after termination of a ventricular tachyarrhythmia or ventricular fibrillation comprises identifying electromechanical disassociation after termination of a ventricular tachyarrhythmia or a fibrillation and inducing or re-inducing ventricular fibrillation and subsequently applying defibrillating shocks to terminate the fibrillation.