Abstract

Objective: To quantify long term effects of cardiac resynchronisation therapy (CRT) by biventricular pacing in patients with heart failure (HF).

Methods: Regional changes in left ventricular (LV) contraction patterns effected by CRT in 19 patients with HF (12 with ischaemia; mean (SD) age 66 (9) years) with bundle branch block were examined by colour Doppler tissue velocity imaging (c-TVI). Time differences during main systolic tissue velocity peak (SYS) were compared in the basal and mid LV interventricular septum and in the corresponding LV free wall segments.

Results: From baseline to long term (9.8 (3.0) months) CRT, ejection fraction increased from 21.8 (5.4)% to 30.8 (7.6)%, LV end diastolic diameter decreased from 7.6 (0.9) cm to 7.1 (0.8) cm, and end systolic diameter decreased from 6.4 (1.2) cm to 6.0 (1.2) cm (p < 0.05). LV peak tissue velocities were unchanged during follow up. At baseline, SYS in LV free wall was typically delayed by an average of 29 ms in the basal LV site and by 18 ms in the mid LV site. The regional movements of the LV free wall and interventricular septum were separated by an average of only 14 ms and −4 ms (p < 0.05) at the basal site and by −21 ms and −16 ms at the mid LV site during short term and long term CRT, respectively.

Conclusions: The improved haemodynamic functions observed during CRT may be explained by a significant resynchronisation of the regional LV movement pattern during long term follow up.