Background: Biventricular cardiac pacing has been used as a complementary form of therapy in patients with severe heart failure. The aim of this study was to evaluate the effect of the synchronous stimulation of both ventricles on the heart function measured by gated blood pool study (GBP).
Material and methods: Ten patients (9 men and 1 woman aged 53-74 years) with end-stage heart failure (HF) were studied. In all patients long-term biventricular pacing (BV) was applied. The obtained results were compared with single-chamber stimulation in 5 patients and with sinus rhythm (SR) in 8 patients. All patients underwent repeated GBP with RBC labelled with 740 MBq of 99 mTc-pertechnetate. The LVEF was calculated according to the standard method based on the count rates. Phase analysis was performed with the standard method using first Fourier element.
Results: Clinically in almost all patients moderate to important symptomatic improvement has been observed. The analysis of LVEF values revealed that BV pacing resulted in significantly higher values only in comparison with SR (21.6% +/- 10.3 v. 20.1% +/- 10.1; p < 0.05). The phase shift between both ventricles by BV pacing was positive and similar to that obtained with SR and RV stimulation (14.0 degrees +/- 29.6 v. 13.4 degrees +/- 37.6 and 7.4 degrees +/- 26.5 v. 6.0 degrees +/- 17.1 respectively). However, in comparison with LV pacing, BV stimulation revealed a change of dominant conduction abnormalities with a delay of RV contraction in relation to LV (9.0 degrees +/- 17.5 v. -3.0 degrees +/- 11.4).
Conclusions: Biventricular pacing results in slight improvement of LVEF in patients with heart failure and can be considered a promising approach in patients with end-stage heart failure. Synchronous stimulation of both ventricles not always results in decrease of interventricular shift, however that observation requires further studies on a larger population.