Congenital heart disease
Impact of Right Ventricular Volume Overload on Three-Dimensional Global Left Ventricular Mechanical Dyssynchrony After Surgical Repair of Tetralogy of Fallot

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This study aimed to test the hypothesis that right ventricular (RV) volume overload may result in left ventricular (LV) systolic dysfunction through induction of LV systolic dyssynchrony after tetralogy of Fallot (TOF) repair. Sixty patients with TOF repair were studied at 14.3 ± 7.2 years after TOF repair. Real-time 3-dimensional echocardiographic data sets were acquired for measurement of LV and RV volumes and derivation of ejection fractions and pulmonary regurgitant volume. The LV systolic dyssynchrony index (SDI) was derived from the dispersion of time to minimum regional volume using a 16-segment model. The results were compared with those of 29 healthy controls. LV SDI was significantly higher in patients than controls (7.4% ± 2.0% vs 3.0% ± 0.9%, p <0.001). The prevalence of LV mechanical dyssynchrony (SDI >4.7%) in patients was 93% (95% confidence interval 87% to 100%). The time to minimum regional volume was significantly longer in all of the 6 basal segments and the midposterior segment (all p <0.05) in patients than controls. Multivariate analysis identified RV end-diastolic volume (β = 0.58, p <0.001), LV ejection fraction (β = –0.38, p <0.001), and LV end-diastolic volume (β = 0.26, p = 0.002) as significant correlates of LV SDI. In conclusion, in patients after TOF repair, RV volume overload has a negative effect on LV systolic function through induction of global LV mechanical dyssynchrony.

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Methods

Sixty patients (34 men), aged 18.9 ± 7.9 years, who have undergone surgical repair of TOF were recruited prospectively from the pediatric cardiac clinic. Of the 60 patients, 5 had TOF with pulmonary atresia. Twenty-nine (13 males) healthy subjects, aged 16.6 ± 6.4 years (p = 0.17), followed up in the cardiac clinic for nonspecific chest pain and palpitation but without documented cardiac arrhythmias; healthy siblings of patients were recruited as controls. The following data were retrieved from

Results

Of the 60 patients, 21 had initial systemic-to-pulmonary arterial shunt palliation. Total correction was performed at 4.5 ± 3.6 years of age with transannular patch enlargement of the RV outflow in 40 patients, without a transannular patch in 10, with a valved conduit insertion in 7, and a nonvalved conduit in 3. All of the patients were asymptomatic at the time of study. The QRS duration of the patients was 143 ± 26 ms. Compared with controls, patients had similar weight (45.2 ± 15.2 kg vs

Discussion

The present study demonstrates that 3-dimensional global LV systolic mechanical dyssynchrony is highly prevalent after surgical repair of TOF. Using 2-dimensional tissue Doppler analysis, El Rahman et al7 has demonstrated delay of septal deformation in 52% of TOF patients studied at a median age of 19 years. Although their findings suggest LV mechanical dyssynchrony, significant overlap in LV deformation delay was noted between their patients and controls. However, we were able to show

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