Measurement of effective aortic valve area using three-dimensional echocardiography in children undergoing aortic balloon valvuloplasty for aortic stenosis.

AIMS: Pressure gradient is used for timing of balloon aortic valvuloplasty for aortic stenosis (AS) in children, but does not correlate well with outcome and is limited if ventricular function is poor. In adults, effective orifice area (EOA) is used to assess AS severity, but EOA by continuity equation or 2D echo is unreliable in children. Three-dimensional echocardiography (3DE) may reliably assess EOA but has not been studied in children. We assessed measurement of aortic valve EOA by 3DE in children with AS before and after balloon aortic valvuloplasty and compared results with change in aortic valve gradient. METHODS: 3DE was performed at time of catheterization before and after balloon aortic valvuloplasty. Using 3DE multiplanar review mode, valve annulus diameter, area, and EOA were measured and compared with change in aortic gradient and degree of aortic insufficiency. RESULTS: Twenty-four 3DE studies in 12 children (mean age 4.4 ± 5.0 years) were analyzed. EOA was measurable in all. Catheter peak gradient decreased from 45 ± 10 to 26 ± 17 mmHg (P = 0.0018). 3DE EOA increased after balloon aortic valvuloplasty (0.59 ± 0.52 cm(2) vs 0.80 ± 0.70 cm(2) ; P = 0.03), without change in valve diameter. EOA change correlated with change in peak (r = 0.77; P = 0.005) and mean (r = 0.60; P = 0.03) aortic valve gradient post balloon aortic valvuloplasty. CONCLUSION: 3DE facilitates EOA measurement in pediatric AS and correlates with change in aortic valve gradient after balloon valvuloplasty.

Relation between left ventricular regional radial function and radial wall motion abnormalities using two-dimensional speckle tracking in children with idiopathic dilated cardiomyopathy.

Left ventricular (LV) regional radial function and its relation to radial wall motion abnormalities have not been investigated in children with idiopathic dilated cardiomyopathy (IDC). Radial strain was measured using 2-dimensional speckle tracking to evaluate regional radial function and wall motion in 6 LV segments in 24 children (0 to 18 years old) with IDC and 16 healthy controls. Patients and controls were similar in age. Patients with IDC had higher heart rates (97 +/- 28 vs 77 +/- 19, p <0.05) and decreased ejection fraction (34 +/- 12% vs 66 +/- 7%, p <0.0001) compared with controls. Radial strain in all segments was significantly lower in patients with IDC. In IDC, average radial strain correlated well with ejection fraction (r = 0.8, p <0.0001). The SD of time to peak radial strain among 6 LV segments was significantly higher in patients with IDC than in controls (56 +/- 38 vs 15 +/- 12 ms, p <0.0001). Segmental peak radial strain correlated closely to time to peak radial strain in controls (r = 0.98, p = 0.0008), but less in patients with IDC (r = 0.76, p = 0.07). In conclusion, LV regional radial function is impaired in pediatric IDC, in association with increased radial dyssynchrony, revealing a possible important mechanism for LV dysfunction in these children.

Evaluation of mechanical dyssynchrony in children with idiopathic dilated cardiomyopathy and associated clinical outcomes.

We studied mechanical dyssynchrony and its association with clinical status in children with idiopathic dilated cardiomyopathy (IDC). The SD of QRS to peak systolic velocity interval by tissue Doppler was measured in 12 left ventricular segments, as a dyssynchrony index (DI), in each child with IDC during a 12-month period. Results were compared with a control cohort. We used the adult-defined DI cutpoint of 32.6 ms to define patients with IDC as "dyssynchronous" or "synchronous" and compared clinical status and outcomes (transplantation listing/death) between these groups. Patients with IDC (n = 23) and controls (n = 14) had similar age, gender, and QRS duration. Patients with IDC had a higher DI than controls (44.8 +/- 23.7 vs 19.9 +/- 8 ms, p <0.0001). A DI >32.6 ms defined mechanical dyssynchrony in 65% of patients with IDC. Dyssynchronous and synchronous patients had similar QRS durations. Age at diagnosis, at dyssynchrony evaluation, and duration of clinical illness were similar in the 2 groups. New York Heart Association score was better in dyssynchronous than in synchronous patients (2 vs 3.1, p <0.05). Number of synchronous and dyssynchronous patients reaching the end point of death or transplantation was similar, although synchronous patients had poorer actuarial survival from the time of diagnosis (hazard ratio 3.25, p = .04). In conclusion, left ventricular mechanical dyssynchrony is prevalent in pediatric IDC. QRS duration alone is inadequate to define dyssynchrony in pediatric IDC, whereas the adult-derived DI of >32.6 ms seems applicable to the pediatric population. In this cohort, the presence of mechanical dyssynchrony was not associated with more severe clinical status or adverse outcomes.