Left ventricular function after long-term treatment with ventricular inhibited compared to atrial triggered ventricular pacing.

The long-term effect of ventricular inhibited (VVI) and atrial triggered ventricular (VAT) pacing on cardiac performance was determined by cardiac catheterization at rest and during exercise in 9 patients with high-degree AV block. Cardiac output (Q) increased at rest by 22% during VAT vs. VVI (5.5 vs. 4.5 l/min, p less than 0.01). An increased stroke volume constituted the difference (75 vs. 63 ml, p less than 0.05). Mean working capacity increased by 12% in the supine position with VAT vs. VVI (p less than 0.05). During exercise Q increased by 40% with VAT vs. VVI (10.2 vs. 7.3 l/min, p less than 0.01) due to an increase in heart rate. Most pressures were largely unchanged. Stroke work and atrial rate decreased during VAT vs. VVI, which may indicate a lower sympathetic activity with VAT vs. VVI. The study demonstrated that hemodynamics advantages of VAT are still obtainable after several years of VVI pacing.