Newer Imaging Modalities in the Assessment of Heart Function in Single Ventricle Hearts

Perinatal Cardiac Functional Adaptation in Hypoplastic Left Heart Syndrome: A Longitudinal Analysis

BACKGROUND

The perinatal transition is characterized by acute changes in cardiac loading. Compared with normal newborn combined cardiac output (CCO), single right ventricular (RV) output of neonates with hypoplastic left heart syndrome (HLHS) is markedly greater. The aim of this study was to examine the mechanisms of cardiac adaptation that facilitate this perinatal transition from late fetal to early neonatal life in HLHS.

METHODS

Prospectively recruited pregnancies complicated by fetal HLHS (n = 35) and healthy control subjects (Ctrl; n = 17) underwent serial echocardiography in late gestation (38 ± 1 weeks) and 6, 24, and 48 hours after birth. Cardiac function was assessed using conventional, Doppler tissue, and speckle-tracking echocardiography.

RESULTS

Term fetuses with HLHS had RV output comparable with Ctrl CCO via higher stroke volume. Compared with both left ventricular and RV indices of Ctrl, they exhibited globular and dilated right ventricles with reduced relative wall thickness (0.40 ± 0.08 vs 0.49 ± 0.10, P < .01), increased Tei index' (HLHS vs Ctrl left ventricle/Ctrl right ventricle: sphericity index, 0.9 ± 0.25 vs 0.5 ± 0.10/0.6 ± 0.11; RV area index, 28 ± 6 vs 15 ± 3/17 ± 5 cm2/m2; Tei index', 0.65 ± 0.11 vs 0.43 ± 0.07/0.45 ± 0.09; P < .0001 for all). Neonates with HLHS generated elevated RV cardiac output compared with Ctrl CCO via higher heart rate and stroke volume, with further RV dilatation, increased longitudinal systolic strain at 48 hours (-17 ± 4% vs -14 ± 3%/ 14 ± 5%) with reduced circumferential and rotational myocardial deformation and altered diastolic function. Neonates with HLHS also demonstrated right atrial enlargement with increased longitudinal strain: 6 hours (33 ± 12% vs 26 ± 6%), 24 hours (37 ± 15% vs 26 ± 13%), and 48 hours (38 ± 11% vs 24 ± 13%) (P < .0001).

CONCLUSIONS

Term fetuses with HLHS exhibit altered RV geometry and RV systolic and diastolic functional parameters. After birth, further alterations in these cardiac parameters likely reflect adaptation to acutely altered RV loading from increasing cardiac output and pulmonary artery flow demands.

How Does Cross-Sectional Imaging Impact the Management of Patients With Single Ventricle After Bidirectional Cavopulmonary Connection?

BACKGROUND

There is currently no consensus regarding the use of surveillance cross-sectional imaging in pediatric patients after bidirectional cavopulmonary connection (BDCPC). We sought to determine how computed tomography with angiography (CTA) and cardiac magnetic resonance (CMR) imaging impacted the clinical management of pediatric patients after BDCPC.

METHODS

A single-center retrospective study including patients with single ventricle who had BDCPC between 2010 and 2019, and CTA/CMR studies obtained in these patients, at ≤5 years of age, and with Glenn physiology. Repeat studies on the same patient were included if the clinical situation had changed. The impact of CTA/CMR studies was categorized as major, minor, or none.

RESULTS

Twenty-four patients (63% male) and 30 imaging studies (22 CTAs) were included. 60% were obtained in patients with hypoplastic left heart syndrome (HLHS); most common indication was Follow-up after an intervention (23%). 6 CMRs were performed on stable HLHS patients as part of a research protocol, with no clinical concerns. The overall impact of CTA/CMR studies was major in 13 cases (43.3%). CTA/CMR studies performed ≥1 year of age (62.5% vs 21.4%, P = .02) and in non-HLHS patients (66.7% vs 27.8%, P = .035) were associated with major impact. Also, 2/6 Research studies were associated with a major impact.

CONCLUSIONS

CTA/CMR imaging in pediatric patients with SV after BDCPC was associated with significant clinical impact in over 40% of cases, with a higher impact if obtained in patients ≥1 year of age and in non-HLHS patients. We cannot disregard the possibility of CMR as a surveillance imaging modality in this population.

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.

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.

Speckle-Tracking Echocardiography Improves Pre-operative Risk Stratification Before the Total Cavopulmonary Connection

INTRODUCTION

Single-ventricle patients with elevated pulmonary vascular resistance (PVR) or end-diastolic pressure (EDP) are excluded from undergoing total cavopulmonary connection (TCPC). However, a subset of patients deemed to be at acceptable risk experience prolonged length of stay (LOS) after TCPC. Routine assessment of ventricular function has been inadequate in identifying these high-risk patients. Speckle-tracking echocardiography (STE) is a novel method for assessment of myocardial deformation that may be useful in single-ventricle patients. The aim of this study was to perform a contemporary preoperative risk assessment for prolonged LOS to determine whether STE improves risk stratification before TCPC.

METHODS

Our single institution's perioperative data were retrospectively collected. The primary outcome was postoperative LOS >14 days. Longitudinal and circumferential STE deformation measures were analyzed on echocardiograms obtained during preoperative catheterization. Patient-specific, echocardiographic, and catheterization data were included in multivariable logistic regression. Receiver operating characteristic area under the curves (AUC) were analyzed.

RESULTS

From 2007 to 2014, 135 patients who underwent TCPC were included in the analysis. The median LOS was 11 (IQR 9-14) days. The PVR (P < .01) and circumferential strain rate (CSR) (P < .01) were the only variables independently associated with LOS >14 days. For every 0.1 s-1 CSR increased, there was a 20% increased odds of prolonged LOS. The AUC for CSR was 0.70. The AUC for PVR and EDP combined was 0.68. The AUC for PVR, EDP, and CSR combined was 0.73.

CONCLUSION

Preoperative CSR is independently associated with LOS >14 days and improves preoperative risk stratification in patients undergoing TCPC.

Perioperative Considerations for Children With Right Ventricular Dysfunction and Failing Fontan

The survival of patients with congenital heart diseases (CHD) has increased in the past decades, resulting in the identification of new characteristics of chronic comorbidities observed in pediatric and adults with CHD. Patients with CHD can present with a broad clinical spectrum of manifestations of congestive heart failure (CHF) at any point throughout their lives that may be related to anatomical or surgical variables. This article focuses on the perioperative assessment of patients with CHD and CHF, with an emphasis on pathophysiologic, diagnostic, and therapeutic alternatives in patients with right ventricular failure and failing Fontan circulation. We also provide descriptions of the effects of sedatives and anesthetics commonly used in this population in diagnostic or invasive procedures.