SEPTAL SHORT ATRIOVENTRICULAR DELAY PACING - ADDITIONAL HEMODYNAMIC IMPROVEMENTS IN HEART-FAILURE

Controversy exists as to whether short AV delay pacing is beneficial i n left ventricular dysfunction with the studies performed coming to di sparate conclusions. The right ventricular apical pacing previously st udied results in asynchronous contraction and relaxation sequences and may limit the potential benefits of short AV delay pacing. In this st udy the hemodynamic effects of septal (resulting in a more physiologic al activation sequence) and apical right ventricular activation were c ompared in 15 patients with heart failure. VDD pacing with AV delays o f 50, 100, and 150 msec was evaluated. Apical VDD pacing did not incre ase the cardiac output significantly, 4.1 +/- 0.75 to 4.45 +/- 0.74 L/ min, whereas septal VDD pacing increased the cardiac output to 4.86 +/ - 0.79 L/min (P = 0.037). Apical pacing increased the cardiac output i n 10 patients and septal pacing in 11 patients. We conclude that selec ted patients with ventricular dysfunction benefit from short AV delay pacing. Septal ventricular activation confers significant hemodynamic improvements over apical activation.