Ventricular dyssynchrony and function improve following catheter ablation of nonseptal accessory pathways in children

Abstract

Introduction: Paradoxical or hypokinetic interventricular septal motion has been described in patients with septal or paraseptal accessory pathways. Data regarding nonseptal pathways is limited.

Methods and results: We quantified left ventricular dyssynchrony and function in 16 consecutive children, 14.2 ± 3.7 years, weighing 53 ± 17 kg, prior to and following catheter ablation of bidirectional septal (N = 6) and nonseptal (N = 10) accessory pathways. Following ablation, the left ventricular ejection fraction increased by 4.9 ± 2.1% (P = 0.038) from a baseline value of 57.0% ± 7.8%. By tissue Doppler imaging, the interval between QRS onset and peak systolic velocity (Ts) decreased from a median of 33.0 ms to 18.0 ms (P = 0.013). The left ventricular ejection fraction increased to a greater extent following catheter ablation of nonseptal (5.9% ± 2.6%, P = 0.023) versus septal (2.5% ± 4.1%, P = 0.461) pathways. The four patients with an ejection fraction <50%, two of whom had left lateral pathways, improved to >50% after ablation. Similarly, the improvement in dyssynchrony was more marked in patients with nonseptal versus septal pathways (difference between septal and lateral wall motion delay before and after ablation 20.6 ± 7.1 ms (P = 0.015) versus 1.4 ± 11.4 ms (P = 0.655)).

Conclusion: Left ventricular systolic function and dyssynchrony improve after ablation of antegrade-conducting accessory pathways in children, with more pronounced changes noted for nonseptal pathways.

Figure 1

Determination of interventricular mechanical delay (IVMD) using pulsed Doppler mode, corresponding to the difference between aortic (a) and pulmonary (b) preejection delay. No significant delay in left ventricular contraction is observed.

Figure 2

Assessment of septal-to-posterior wall motion delay (SPWMD) using M-mode imaging. Normal SPWMD (<130 ms) is demonstrated.

Figure 3

Determination of the delay between time-to-peak systolic velocity at basal septal (a) and basal lateral (b) segments using tissue Doppler imaging. A significant delay is demonstrated in this patient (no. 10).

Figure 4

Determination of time-velocity curves using color-coded tissue Doppler and Q-analyses (from left ventricular septal and lateral wall sample points selected in an apical long-axis view). In this example (patient no. 6), no significant delay is demonstrated between septal and lateral left ventricular walls following catheter ablation.

Figure 5

Echocardiographic parameters prior to and following catheter ablation. LVEF denotes left ventricular ejection fraction; SPWMD, septal-to-posterior wall motion delay; ESD, electrosystolic delay (or time-to-peak systolic velocity).