Left ventricular torsional mechanics and diastolic function in congenital heart block with right ventricular pacing

Background: The effects of right ventricular (RV) pacing on left ventricular (LV) diastolic function are unknown. This study aimed to test the hypothesis that right ventricular (RV) pacing is associated with LV diastolic dysfunction and impairment of LV torsion in children and young adults with congenital heart block.

Methods: Eighteen patients aged 20 ± 7 years and 12 healthy controls aged 19 ± 7 years were studied. Transmitral and mitral annular diastolic velocities and global longitudinal diastolic strain rate were determined and compared between the 2 groups. Parameters of LV torsion including peak systolic basal and apical rotations, and systolic twisting and diastolic untwisting velocities were further determined by speckle tracking echocardiography. In 12 patients, these parameters were compared before and after interruption of RV pacing.

Results: Compared with controls, patients had significantly lower mitral early diastolic annular velocity (p=0.007), LV global diastolic strain rate (p<0.001), basal (p<0.001) and apical (p=0.002) rotations, peak systolic torsion (p<0.001), and peak systolic twisting velocities (p=0.009). In patients, the peak diastolic untwisting velocity correlated with peak systolic torsion (r=0.64, p=0.004) and peak systolic twisting velocity (r=0.74, p<0.001). No significant improvement in LV diastolic function or torsion was observed during pacing interruption (all p>0.05).

Conclusion: Right ventricular pacing in childhood is associated with LV diastolic dysfunction and impaired LV torsion, which do not improve with pacing interruption.