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.

Left ventricular noncompaction in children.

OBJECTIVE: Left ventricular noncompaction (LVNC) is an uncommon type of cardiomyopathy in children. We sought to determine the clinical presentations and outcomes of children diagnosed to have LVNC. DESIGN: The case records of children diagnosed to have LVNC between 1999 and 2007 were reviewed. The diagnosis was based on echocardiographic finding of a thick noncompacted myocardium layer characterized by a trabecular meshwork with deep endomyocardial spaces. RESULTS: Ten patients (seven males) were diagnosed to have LVNC at a median age of 2 years (range, 7 days to 12 years). Seven patients had isolated LVNC while three had associated structural congenital heart diseases. The right ventricle was also involved in two patients. Clinical presentations included congestive heart failure in eight patients, asymptomatic heart murmur in one, and syncope with exercise intolerance in one. At presentation, cardiomegaly was found in nine patients, electrocardiographic abnormalities in nine, and impaired LV contraction in six. Eight patients received anti-heart failure medications. Three patients died at a median of 1.5 years after diagnosis, two died suddenly of unknown causes, and one of heart failure. The seven surviving patients were followed up for a median of 2 years (range, 2 months to 3 years). Three patients developed cardiac arrhythmias. The LV function improved in three patients and worsened in one on follow-up. None of the patients developed thromboembolic complications. CONCLUSIONS: Left ventricular noncompaction in children is a heterogeneous condition. Long-term follow-up for development of progressive LV dysfunction and cardiac arrhythmias is indicated.