Biventricular Pacemaker Synchronization: A Numerical Cardiocirculatory Model Application

Biventricular pacemakers are used for cardiac resynchronization therapy in order to treat the delay in ventricular contractions that occurs in patients with severe heart failure (ejection fraction < 35%, QRS duration > 130ms) and with bundle branch blocks. These diseases affect 600,000 patients in Italy and there are 87,000 new cases every year [1]. Resynchronization therapy tends to restore the normal coordinated pumping action of the ventricles by overcoming the electrical conduction delay by using biventricular pacemaker. It has been observed that implanting a biventricular pacemaker improves quality of life and physical activity resistance increasing ejection fraction. But it is noted that 30% of patients doesn't (do not?) have an improvement because of an absent or incomplete response. Conventional biventricular pacing have three leads: one placed in the right atrium, the second one in the right ventricle and the last in a vein on the surface of the left ventricle. However it is not clear if this solution can completely guarantee inter-ventricular and atrio-ventricular synchronization also considering that synchronization must be specific for each patient. In fact, assuming that pacemaker is correctly placed, every patient presents different clinical responses like modest improvement in exercise tolerance and quality of life, congestive heart failure severity reduction, echo measures and neurohormones.. The aim of this work is to simulate advanced heart failure and severe arrhythmia, and to optimize cardiac pacing with biventricular pacemaker. The numerical model of cardiovascular system, CARDIOSIM© [2] enables to simulate different disease conditions due to different degrees of pathophysiological impairment together with their effect on cardiovascular function.. It has been modified to study the effects of ventricular synchronization.