Abstract: The apparatus and method of the present invention are used to detect the ECG and/or blood pressure (BP) waveforms and measure the R-R and Q-T intervals from the detected ECG signals, so as to determine the pulse structure of the heart stimulating signals, and to stimulate the heart. The heart is stimulated by the stimulating signals which includes a pacing pulse train applied to atrium for forming an artificial heart rhythm, and an inducing pulse train applied to ventricle for introducing ME or VT waveforms. By adjusting the time location and amplitude of the inducing pulses relative to the pacing pulses, the ME or VT waveforms are induced in the ECG signals. By detecting the ECG and/or BP waveforms, the ME or VT is identified and at the same time the heart stimulation is stopped. Then the induced ME or VT waveforms and the amplitude of the inducing pulse which induces the ME or VT waveforms are displayed and the ventricular fibrillation threshold is derived according to this amplitude.