Stress Echocardiographic Evaluation for D-Transposition of the Great Arteries after Atrial Redirection: Unmasking Early Signs of Myocardial Dysfunction and Baffle Stenosis

Long-term myocardial performance of the systemic right ventricle during exercise in patients with transposition of the great arteries and atrial switch operation

The most common clinical scenario in which RV is systemic, is dextroposition transposition of the great arteries (dTGA). This is the second most common cyanotic congenital heart disease [2]. Before the arterial switch operation was introduced in 1975 [3], patients with dTGA were treated with the Mustard or Senning procedure, also referred to as the atrial switch operation, where the systemic veins are routed to the subpulmonary morphological left ventricle and the pulmonary veins are routed to the systemic right ventricle [4].The atrial switch operation leaves the RV in a systemic position, leading to gradual RV dysfunction and RV failure [5-8]. In this context, sRV functional reserve and its ability to augment performance with exercise performance is not well studied.

Systolic and diastolic functional reserve of the subpulmonary and systemic right ventricles as assessed by pharmacologic and exercise stress: A systematic review

We performed a systematic review of the literature on the assessment of subpulmonary and systemic right ventricular (RV) functional reserve during pharmacological and exercise stress in congenital heart patients and patients with pulmonary arterial hypertension (PAH). Literature search was conducted using PubMed, EMBASE, and MEDLINE from their inception up to August 2020. Of 913 records identified, 56 studies with a total of 1730 patients were included. Of the 56 studies, 23 assessed subpulmonary RV functional reserve in repaired tetralogy of Fallot patients, 19 assessed systemic RV reserve in patients with transposition of the great arteries (TGA) after atrial switch and those with congenitally corrected TGA, and 14 assessed subpulmonary RV research in patients with PAH. Pharmacological and exercise stress was used, respectively, in 22 and 34 studies. The main findings were (1) impairment of RV systolic and diastolic functional reserve, (2) associations between impaired functional reserve and worse baseline functional parameters, and (3) prognostic implications of RV systolic functional reserve on clinical outcomes in patients with volume and/or pressure-loaded subpulmonary and systemic right ventricles. Further studies are required to establish the incremental value of incorporating stress studies of RV systolic and diastolic function in the clinical management algorithm of congenital heart patients and patients with PAH.

Baffle Complications in Adults After Atrial Switch for Transposition of the Great Arteries

BACKGROUND

Baffle complications, ie, leakage or stenosis, after an atrial switch operation (AtrSO) for transposition of the great arteries (TGA) are difficult to detect with the use of routine transthoracic echocardiography (TTE). We examined baffle interventions and the prevalence of baffle complications.

METHODS

This dual-centre study followed TGA-AtrSO patients for the occurrence of baffle interventions. In addition, in 2017-2019, prevalence of baffle complications was determined in patients undergoing routine contrast-enhanced (CE) TTE including various hemodynamic conditions and computed tomography (CT). Baffle leaks were defined as right-to-left shunting on CE-TTE and baffle stenosis as a systemic venous baffle diameter of < 10 mm on CT.

RESULTS

In total, 67 TGA-AtrSO patients were followed to a median age of 38 (interquartile range 34-42) years, for a median of 9 (6-13) years. Baffle interventions were documented in 24 patients (36%). Cumulative risk of baffle interventions was 25% after 15 years of follow-up. Prevalence of baffle complications was determined in 29/67 patients. In total, 4 (14%) had patent baffles, 11 (38%) had leakage only, 5 (17%) had stenosis only, and 9 (31%) had both, while 24/29 (84%) were asymptomatic. Although baffle leaks were not associated with clinical characteristics, peak work rate during exercise TTE was lower in patients with vs without stenosis (89 ± 24 W vs 123 ± 21 W; P < 0.001).

CONCLUSIONS

Baffle complications are common in TGA-AtrSO. The cumulative risk of baffle interventions was 25% after 15 years of follow-up. CE-TTE uncovered asymptomatic baffle leakage in the majority of patients, especially with examination during exercise. CT revealed baffle stenosis in almost half of the patients, which was associated with decreased exercise tolerance. Awareness of these findings may alter clinical follow-up.

Feasibility and Role of Right Ventricular Stress Echocardiography in Adult Patients

Background:

The great technological advancements in the field of echocardiography have led to applications of stress echocardiography (SE) in almost all diagnostic fields of cardiology, from ischemic heart disease to valvular heart disease and diastolic function. However, the assessment of the right ventricle (RV) in general, and in particular in regard to the contractile reserve of the RV, is an area that has not been previously explored. We, therefore, propose a study to investigate the potential use of SE for the assessment of RV function in adult patients.

Aims and objectives:

The primary aim is to evaluate the feasibility of right ventricular SE. The secondary aim is to assess right ventricular contractile reserve.

Matherials and Methods:

Eighty-one patients undergoing a physical or dobutamine stress echocardiogram for cardiovascular risk stratification or chest pain were the subject of the study. An exercise leg cycle using a standard WHO protocol was used to simultaneously assess the right and left ventricular global and regional function as well as acquiring Doppler data. Whereas the patient had limitations in mobility, a dobutamine SE was be performed. We evaluated the average values of tricuspid annular plane systolic excursion (TAPSE), fractional area change (FAC), S-wave, systolic pulmonary artery pressure (sPAP), and right ventricle global longitudinal (free wall) strain (RVGLS) during baseline and at the peak of the effort. RV contractile reserve was defined as the change in RVGLS from rest to peak exercise. We also assessed the reproducibility of these measurements between two different expert operators (blind analysis).

Results:

At least 3 over 5 RV function parameters were measurable both during baseline and at the peak of the effort in 95% of patients, while all 5 parameters in 65% of our population, demonstrating an excellent feasibility. All RV-studied variables showed a statistically significant increase (P < 0.001) at peak compared to the baseline. The average percentage increases at peak were 31.1% for TAPSE, 24.8% for FAC, 50.6% for S-wave, 55.2% for PAPS, and 39.8% for RV strain. The reproducibility between operators at baseline and peak was excellent. Our study demonstrates that TAPSE, FAC, and S-wave are highly feasible at rest and at peak, while TAPSE, S-wave, and sPAP are the most reliable measurements during RV stress echo.

Conclusion:

RVGLS is useful in the assessment of RV contractile reserve in patients with good acoustic window. Further studies are needed to evaluate the impact of contrast echocardiography in improving RV contractile reserve assessment during SE.

Advanced Imaging to Phenotype Patients With a Systemic Right Ventricle

Background

Reduced ventricular function and decreased exercise capacity are widespread in adults with complete transposition of the great arteries after atrial switch (TGA‐Mustard/Senning) and congenitally corrected TGA (ccTGA). Advanced imaging techniques may help to better phenotype these patients and evaluate exercise cardiac response.

Methods and Results

Thirty‐three adults with a systemic right ventricle (70% TGA‐Mustard/Senning, 37±9 years of age, 24% female, 94% New York Heart Association class I‐II) underwent echocardiogram, cardiopulmonary exercise testing, and cardiovascular magnetic resonance imaging at rest and during a 4‐stage free‐breathing bicycle test. They were compared with 12 healthy controls (39±10 years of age, 25% female, all New York Heart Association class I). TGA‐Mustard/Senning patients had a higher global circumferential strain (−15.8±3.6 versus −11.2±5.2%, P=0.008) when compared with ccTGA, whereas global longitudinal strain and systemic right ventricle contractility during exercise were similar in both groups. Septal extracellular volume (ECV) in ccTGA was significantly higher than in TGA‐Mustard/Senning (30.2±2.0 versus 27.1±2.7%, P=0.005). During exercise, TGA‐Mustard/Senning had a fall in end‐diastolic volume and stroke volume (11% and 8%, respectively; both P≤0.002), whereas ccTGA could increase their stroke volume in the same way as healthy controls. Because of a greater heart rate reserve in TGA‐Mustard/Senning (P for interaction=0.010), cardiac index and peak oxygen uptake were similar between both patient groups.

Conclusions

Caution should be exercised when evaluating pooled analyses of systemic right ventricle patients, given the differences in myocardial contraction pattern, septal extracellular volume, and the exercise response of TGA‐Mustard/Senning versus ccTGA patients. Longitudinal follow‐up will determine whether abnormal exercise cardiac response is a marker of earlier failure.