An apparatus for determining heart transplant rejection of a heart in a patient includes at least two electrodes adapted to be sewn into the heart that span the left ventricle. The apparatus includes a voltage generator adapted to be inserted in the patient which generates a voltage to the two electrodes and senses the resulting voltage from the two electrodes. A method for determining heart transplant rejection of a heart in a patient. A pacemaker for a patient (including bi-ventricular pacing and AICDs). The pacemaker includes an RV lead having four electrodes adapted to be inserted into the RV apex. The pacemaker includes a voltage generator which generates a voltage signal to the electrodes and senses the instantaneous voltage along the length of the RV and determines the real and imaginary components to remove the myocardial components of the septum and RV free wall to determine absolute RV blood volume. The pacemaker includes a battery connected to the voltage generator. The pacemaker includes a defibrillator connected to the battery. The pacemaker can also be a bi-ventricular pacemaker to restore RV and LV synchrony during contraction. A method for assisting a heart of a patient.