Echocardiographic evaluation of the single right ventricle in congenital heart disease: results of new techniques

Inter-observer and Inter-vendor Variability in Strain Measurements in Patients with Single Right Ventricular Anatomy

Myocardial strain offers new insights into ventricular performance, There are software packages from several different companies used to ascertain this, and little data is available in patients with single right ventricle (sRV) physiology. We aimed to compare the analysis of two strain software applications using a cohort of patients with sRV for both inter-vendor and inter-observer variability. Echocardiograms from 85 patients with sRV (122 separate studies) were prospectively evaluated. All had Glenn and/or Fontan palliation. Longitudinal 4-chamber (4LS), inflow/outflow (IO), circumferential, and radial strain were assessed using Velocity Vector Imaging (VVI, Seimens, Munich) and Automated Functional Imaging (AFI, General Electric, Boston) software. In a subset of 45 patients (61 separate studies), strain measurements were obtained by two sonographers so a paired "inter-observer" analysis could be performed. A moderate correlation between measurements made by the two systems was observed. Circumferential strain assessment had the highest R value (0.77) with all others having R values < 0.6. Both software packages showed modest inter-observer reproducibility for longitudinal and circumferential strain. VVI intraclass correlation coefficients (ICC) for 4LS and average circumferential strain (ACS) were 0.6 and 0.58, compared to 0.68 and 0.59 for AFI. Other than radial strain and VVI IO inferior strain, mean strain differences between AFI and VVI were ≤ 1%. Inter-observer variability is modest, however, mean differences are minimal suggesting reasonable clinical reliability. Inter-vendor variability is greater and not as clinically reliable. In patients with sRV, serial assessments with strain should be performed using the same software.

Quantitative Phenotyping of Xenopus Embryonic Heart Pathophysiology Using Hemoglobin Contrast Subtraction Angiography to Screen Human Cardiomyopathies

Congenital heart disease (CHD) is a significant cause of mortality in infants and adults. Currently human genomic analysis has identified a number of candidate genes in these patients. These genes span diverse categories of gene function suggesting that despite the similarity in cardiac lesion, the underlying pathophysiology may be different. In fact, patients with similar CHDs can have drastically different outcomes, including a dramatic decrease in myocardial function. To test these human candidate genes for their impact on myocardial function, we need efficient animals models of disease. For this purpose, we paired Xenopus tropicalis with our microangiography technique, hemoglobin contrast subtraction angiography (HCSA). To demonstrate the gene-teratogen-physiology relationship, we modeled human cardiomyopathy in tadpoles. First we depleted the sarcomeric protein myosin heavy chain 6 (myh6) expression using morpholino oligos. Next, we exposed developing embryos to the teratogen ethanol and in both conditions showed varying degrees of cardiac dysfunction. Our results demonstrate that HCSA can distinguish biomechanical phenotypes in the context of gene dysfunction or teratogen. This approach can be used to screen numerous candidate CHD genes or suspected teratogens for their effect on cardiac function.

Longitudinal Myocardial Deformation Does Not Predict Single Ventricle Ejection Fraction Assessed by Cardiac Magnetic Resonance Imaging in Children with a Total Cavopulmonary Connection

Survival of children with single ventricle heart defects after the total cavopulmonary connection (TCPC) has improved, but impaired cardiac function remains a major cause of morbidity and mortality. Cardiac magnetic resonance imaging (cMRI) is the gold standard in assessing single ventricle volume and function, but high costs and limited availability hamper its routine use. A cheaper and more available alternative is echocardiography. Myocardial function can be studied in more detail using speckle tracking echocardiography (STE). The purpose of the study was to describe the association between myocardial deformation assessed by speckle tracking echocardiography (STE) and single ventricle function assessed by cMRI and to evaluate differences in myocardial deformation in children with single left and single right ventricular morphology. Cross-sectional, multicenter study in 77 children after TCPC was conducted. STE segmental and global longitudinal peak strain and systolic strain rate (SR) of the dominant ventricle were measured. Impaired SV function by cMRI was defined as ejection fraction (EF) < 45%. Mean age was 11.8 (range 9.7-14.3) years. Pearson R for cMRI EF versus global longitudinal strain and SR was - 0.25 (p = 0.06) and - 0.03 (p = 0.82), respectively. Global single ventricle longitudinal strain and SR was similar in patients after TCPC with single left and single right ventricular morphology (- 19.0 ± 3.1% vs 19.2 ± 3.2%, p = 0.94). STE myocardial deformation parameters do not correlate with single ventricle ejection fraction assessed by cMRI.

Survey of how pediatric cardiologists noninvasively evaluate patients with hypoplastic left heart syndrome

BACKGROUND

The evaluation of right ventricular (RV) function is important in patients with hypoplastic left heart syndrome (HLHS). Echocardiographic qualitative grading has been the prevalent method used in the past, but newer technologies allowing for quantitative assessment of RV function may have changed this fact. The goal of this study was to determine the current routine noninvasive evaluation of patients with HLHS and what, if any, methods are used to assess systolic and diastolic function in this population.

METHODS

Web-based survey was conducted using various listservs. Timing of echocardiograms between surgical stages was assessed. Methods of assessing systolic and diastolic function were evaluated.

RESULTS

Two hundred seventy-seven physicians who averaged 12.8 ± 9.6 years removed from training responded. Largest percentage of respondents was echocardiographers (44.2%) in a university-based practice (73.3%) from North America (91.7%). There were 54.3% of respondents who performed echocardiograms monthly between stages I and II, 48.8% who performed echocardiograms every 6 months between stages II and III, and 67.0% who performed echocardiograms annually after stage III procedure. The main method for systolic grading was qualitative grading (95.5%) and for diastolic grading were tricuspid blood inflow velocities (56.8%). Qualitative grading was considered the method of choice for systolic grading for 38.8% of respondents and tissue Doppler velocities was the method of choice for diastolic grading for 35.3% of respondents. There were 4.0% of respondents who routinely perform a cardiac magnetic resonance imaging (cMRI) between stages I and II, 8.0% between stages II and III, and 24.2% after stage III procedure.

CONCLUSION

Variability in the noninvasive assessment of the RV in patients with HLHS continues to exist. Qualitative RV systolic assessment was still the predominant method used to assess function despite newer imaging techniques to allow for quantification. Future studies are needed to determine which values are most useful in reviewing function in this complex patient population.