RIGHT VENTRICULAR PRESSURE DURING VENTRICULAR ARRHYTHMIAS IN HUMANS - POTENTIAL IMPLICATIONS FOR IMPLANTABLE ANTITACHYCARDIA DEVICES

Implantable defibrillators use algorithms based on ventricular electrographic data to detect the onset and termination of arrhythmias, but these algorithms do not always differentiate hemodynamically stable from unstable arrhythmias. Although, ideally, left ventricular function should be used to assess the hemodynamic state, right ventricular pulse pressure can be assessed in humans on a long-term basis with a transvenous lead. The potential utility of right ventricular pulse pressure to assess hemodynamic stability was studied in 22 patients with induced ventricular arrhythmias. Right ventricular pressure was measured with use of a transvenous right ventricular endocardial pacing lead with a piezoelectric bender pressure sensor 3 cm from its tip. Single ventricular premature paced beats administered in up to a bigeminal frequency did not alter the mean right ventricular pulse pressure (control 33.7 ± 26, bigeminy 35.7 ± 26 mm Hg):. Twenty-one episodes of induced ventricular tachycardia were studied in the electrophysiology laboratory. Five seconds after tachycardia induction, hemodynamically stable ventricular tachycardia had a longer cycle length (294 ± 41 ms) and the right ventricular pulse pressure ratio was higher (0.55 ± 0.26) than that in unstable ventricular tachycardia (cycle length 256 ± 55 ms, p = 0.06; pulse pressure ratio 0.26 ± 0.09, p < 0.05). Twenty episodes of ventricular fibrillation were induced in eight patients. One second after induction, right ventricular pulse pressure decreased from 25 ± 5 to 6 ± 3 mm Hg (p < 0.05). On the first beat after defibrillation, right ventricular pulse pressure increased to 24 ± 14 mm Hg, a level not significantly different from that before the induction of ventricular fibrillation. This rapid decrease of right ventricular pulse pressure during ventricular fibrillation and immediate recovery after defibrillation is useful for detecting ventricular fibrillation onset and termination. Right ventricular pulse pressure can differentiate hemodynamically stable from unstable ventricular tachycardia. These data suggest that this variable may be of use in automatic implantable antitachycardia/defibrillation devices. © 1990.