No abstract

Hypertrophic Cardiomyopathy (HCM) is a disease with variable rate of progression. Young age is an independent risk factor for poor outcome in HCM. The influence of renin-angiotensin-aldosterone (RAAS) genotype on the progression of HCM in children is unknown. Children with HCM (n = 65) were enrolled prospectively across two centers (2001-2005). All subjects were genotyped for five RAAS gene polymorphisms previously associated with LV hypertrophy (pro-LVH): AGT M235T, ACE DD, CMA-1903 A/G, AGTR1 1666 A/C and CYP11B2-344 C/T. Linear regression models, based on maximum likelihood estimates, were created to assess the independent effect of RAAS genotype on LV hypertrophy (LVH). Forty-six subjects were homozygous for <2 and 19 were homozygous for > or =2 pro-LVH RAAS polymorphisms. Mean age at presentation was 9.6 +/- 6 years. Forty children had follow-up echocardiograms after a median of 1.5 years. Indexed LV mass (LVMI) and LV mass z-scores were higher at presentation and follow-up in subjects with > or =2 pro-LVH genotypes compared to those with <2 (P < 0.05). Subjects with > or =2 pro-LVH genotypes also demonstrated a greater increase in septal thickness (IVST) and in LV outflow tract (LVOT) obstruction on follow-up (P < 0.05). On multivariate analysis, a higher number of pro-LVH genotypes was associated with a larger effect size (P < 0.05). Pro-LVH RAAS gene polymorphisms are associated with progressive septal hypertrophy and LVOT obstruction in children with HCM. Identification of RAAS modifier genes may help to risk-stratify patients with HCM.

Decreased flow-mediated dilation is associated with decreased cardiovascular fitness, increased systolic pressure reactivity to various stressors, and increased indices of body fatness in asymptomatic youth. Further research is warranted to better understand early relationships between this noninvasive measure of endothelial function and cardiovascular risk factors in youth.

Three-dimensional echocardiography has required motorized external scanning devices that move a standard echo transducer to obtain data sets before reconstruction. These transducer holders are susceptible to axis alignment errors and transducer movement. The use of a three-dimensional workstation makes acquisition cumbersome. An internally rotating 5-MHz "omniplane" transthoracic transducer, specifically designed for three-dimensional echocardiography, and an integrated three-dimensional acquisition software package that allows single machine acquisitions were validated in 50 pediatric patients. Children were 1 day to 16 years old and had 22 different cardiac pathological conditions imaged. Ninety-eight of the 104 (94%) data sets collected were successfully reconstructed in three dimensions. Acquisitions took 3-6 minutes depending on the increment of internal rotation. Minimum total study time to set up and complete the acquisition was 12 minutes. The new probe and software makes three-dimensional acquisitions and reconstructions of consistently high quality, rapid, reliable, and user friendly.