Left Ventricular Retraining and Double Switch in Patients With Congenitally Corrected Transposition of the Great Arteries

Pathogenesis and Surgical Treatment of Congenitally Corrected Transposition of the Great Arteries (ccTGA): Part III

Congenitally corrected transposition of the great arteries (ccTGA) is an infrequent and complex congenital malformation, which accounts for approximately 0.5% of all congenital heart defects. This defect is characterized by both atrioventricular and ventriculoarterial discordance, with the right atrium connected to the morphological left ventricle (LV), ejecting blood into the pulmonary artery, while the left atrium is connected to the morphological right ventricle (RV), ejecting blood into the aorta. Due to this double discordance, the blood flow is physiologically normal. Most patients have coexisting cardiac abnormalities that require further treatment. Untreated natural course is often associated with progressive failure of the systemic right ventricle (RV), tricuspid valve (TV) regurgitation, arrhythmia, and sudden cardiac death, which occurs in approximately 50% of patients below the age of 40. Some patients do not require surgical intervention, but most undergo physiological repair leaving the right ventricle in the systemic position, anatomical surgery which restores the left ventricle as the systemic ventricle, or univentricular palliation. Various types of anatomic repair have been proposed for the correction of double discordance. They combine an atrial switch (Senning or Mustard procedure) with either an arterial switch operation (ASO) as a double-switch operation or, in the cases of relevant left ventricular outflow tract obstruction (LVOTO) and ventricular septal defect (VSD), intra-ventricular rerouting by a Rastelli procedure. More recently implemented procedures, variations of aortic root translocations such as the Nikaidoh or the half-turned truncal switch/en bloc rotation, improve left ventricular outflow tract (LVOT) geometry and supposedly prevent the recurrence of LVOTO. Anatomic repair for congenitally corrected ccTGA has been shown to enable patients to survive into adulthood.

Echocardiographic Predictors of Readiness for Double Switch Operation and Postoperative Ejection Fraction in Patients With Congenitally Corrected Transposition of the Great Arteries Undergoing Left Ventricular Retraining

BACKGROUND

In patients with congenitally corrected transposition of the great arteries (ccTGA), assessment of readiness for the double switch operation (DSO) after pulmonary arterial band (PAB) placement involves cardiac magnetic resonance imaging (cMRI) to measure left ventricular ejection fraction (LVEF) and mass and cardiac catheterization (catheterization) to assess the ratio of left ventricular to right ventricular pressure (LV:RVp). The aims of this study were to describe the relationships between echocardiographic and catheterization and cMRI measures of readiness for DSO and to develop risk factors for left ventricular (LV) dysfunction after DSO on the basis of echocardiographic measures of ventricular-arterial coupling (VAC).

METHODS

Patients with ccTGA undergoing LV retraining at a DSO referral center were reviewed. LVEF measured by echocardiography was compared with that measured by cMRI, and LV:RVp measured by echocardiography was compared with that measured by catheterization using Bland-Altman analysis. The relationship between preoperative VAC markers and postoperative echocardiography was analyzed using ventricular end-systolic elastance (EES) and a novel marker consisting of the product of LVEF and LV:RVp (EFPR).

RESULTS

Thirty-one patients with 56 evaluations for DSO were included, 24 of whom underwent DSO. Echocardiographic LVEF correlated well with cMRI LVEF (r = 0.79), and Bland-Altman analysis slightly overestimated cMRI LVEF (mean difference, +3%). Echocardiographic LVEF had a moderate ability to identify normal cMRI LVEF (area under the curve, 0.80) and at an optimal cut point of echocardiographic LVEF threshold of 61%, there was 71% sensitivity and 76% specificity to detect cMRI LVEF ≥ 55%. Echocardiographic LV:RVp correlated well with LV/RVp by catheterization (r = 0.77) and slightly underestimated the catheterization value (mean difference, -0.11). Echocardiographic LV:RVp had a good ability to identify adequate LV:RVp by catheterization (area under the curve, 0.95) and at an optimal echocardiography cut point of 0.75 had 100% sensitivity and 85% specificity to detect a catheterization LV:RVp >0.9. Echocardiography-based criteria for DSO readiness (echocardiographic LVEF of 61% and LV:RVp of 0.75) demonstrated specificity of 97% and positive predictive value of 96% for published criteria of DSO readiness (cMRI LVEF of 55% and catheterization LV:RVp of 0.9). EES and EFPR correlated with post-DSO LVEF (ρ = 0.72 and ρ = 0.60, respectively). EFPR of 0.51 demonstrated 78% sensitivity and 100% specificity for post-DSO LV dysfunction (LVEF < 55%). Age at first PAB also strongly correlated with post-DSO LVEF (ρ = 0.75). No patient with first PAB at <1 year of age exhibited post-DSO LV dysfunction.

CONCLUSIONS

Echocardiographic measures of LVEF and LV:RVp are reliable indicators of reference standard modalities and can guide management during retraining. The preoperative VAC markers EES and EFPR may be useful markers of post-DSO LV dysfunction. Values of echocardiographic LV:RVp >0.75 are likely to meet pressure-generation criteria for DSO and should be considered for referral to catheterization and cMRI evaluation for DSO. PAB placement before 1 year of life may optimize LV outcomes in patients considered for DSO.

Results of the Double Switch Operation in Patients Who Previously Underwent Left Ventricular Retraining

BACKGROUND

Congenitally corrected transposition of the great arteries (CC-TGA) is a complex form of congenital heart disease that has numerous subtypes. While most patients with CC-TGA have a large ventricular septal defect (VSD) and pulmonary stenosis, there are some patients who have either no VSD or a highly restrictive VSD. These patients will require left ventricular (LV) retraining prior to double switch. The purpose of this study was to review our experience with the double switch procedure in patients who had previously undergone LV retraining.

METHODS

This was a retrospective review of a single institution experience with the double switch procedure in patients who had undergone LV retraining (2002-present).

RESULTS

Forty-five patients underwent double switch following LV retraining. Of these, 39 had an arterial switch with hemi-Mustard/bidirectional Glenn and six had a Senning. The median cross-clamp time was 135 min (range 71-272) and median bypass time was 202 min (range 140-430 min). Median hospital length of stay was eight days (range 4-108). There were no in-hospital deaths. Median duration of follow-up was 30 months (range 0-175). One patient subsequently underwent heart transplantation and died 65 months following double switch. At follow-up, 41 of the 44 survivors (93%) have normal or low normal LV function and 40 of the 44 survivors (91%) have no or trace mitral regurgitation.

CONCLUSIONS

The data demonstrate early and mid-term survival of 100% and 97%. Ninety-three percent had preserved LV function. These results suggest that patients with CC-TGA who undergo LV retraining and double switch can have excellent clinical outcomes.

Comparison of long-term outcomes of atrial switch with Rastelli and physiological repair using left ventricle-to-pulmonary artery conduit for levo-transposition of the great arteries

OBJECTIVES

The objectives of this study was to compare the long-term outcomes of anatomic repair using atrial switch with the Rastelli procedure versus physiological repair with left ventricle-to-pulmonary artery conduit for patients with levo-transposition of the great arteries, ventricular septal defect, and left ventricular outflow tract obstruction.

METHODS

Of patients with levo-transposition of the great arteries who underwent biventricular repair between 1978 and 2001, 31 hospital survivors after anatomic repair of atrial switch and the Rastelli (anatomic group) and 14 hospital survivors after physiological repair with left ventricle-to-pulmonary artery conduit (physiological group) were enrolled. Survival rates, reoperation rates, and most recent conditions were compared.

RESULTS

The overall survival rate at 20 years was 79.7% (95% CI, 66.4%-95.6%) in the anatomic group and 85.1% (95% CI, 68.0%-100%) in the physiological group (P = .87). The reoperation rate at 10 years was 19.8% (95% CI, 5.6%-34.0%) in the anatomic group and 52.0% (95% CI, 25.0%-79.1%) in the physiological group (P = .067). Only patients in the physiological group underwent systemic tricuspid valve replacement. The anatomic group showed a better cardiac index at catheterization (2.79 ± 0.75 L/min/m2 vs 2.30 ± 0.54 L/min/m2; P = .035), lower serum brain natriuretic peptide (73 ± 86 pg/mL vs 163 ± 171 pg/mL; P = .024), and better maximal oxygen uptake in the treadmill test (64.1 ± 16.5% vs 52.7 ± 17.8% of predicted normal; P = .036), although the period until most recent catheterization, blood inspection, and treadmill testing were earlier in the anatomic group.

CONCLUSIONS

Preservation of the left ventricle as the systemic ventricle using anatomic repair contributes to better cardiopulmonary condition compared with physiological repair.

Outcomes After Anatomic Versus Physiologic Repair of Congenitally Corrected Transposition of the Great Arteries: A Systematic Review and Meta-Analysis

Surgical treatment for congenitally corrected transposition of the great arteries is widely debated, with both physiologic repair and anatomic repair holding advantages and disadvantages. This meta-analysis, which includes 44 total studies consisting of 1857 patients, compares mortality at different time points (operative, in-hospital, and post-discharge), reoperation rates, and postoperative ventricular dysfunction between these two categories of procedures. Although anatomic and physiologic repair had similar operative and in-hospital mortality, anatomic repair patients had significantly less post-discharge mortality (6.1% vs 9.7%; P = .006), lower reoperation rates (17.9% vs 20.6%; P < .001), and less postoperative ventricular dysfunction (16% vs 43%; P < .001). When anatomic repair patients were subdivided into those who had atrial and arterial switch versus those who had atrial switch with Rastelli, the double switch group had significantly lower in-hospital mortality (4.3% vs 7.6%; P = .026) and reoperation rates (15.6% vs 25.9%; P < .001). The results of this meta-analysis suggest a protective benefit of favoring anatomic repair over physiologic repair.

Pulmonary Artery Banding for Dilated Cardiomyopathy in Children: Returning to the Bench from Bedside

Current treatment paradigms for end-stage dilated cardiomyopathy (DCM) in children include heart transplantation and mechanical support devices. However, waitlist mortality, shortage of smaller donors, time-limited durability of grafts, and thrombo-hemorrhagic events affect long-term outcomes. Moreover, both these options are noncurative and cannot preserve the native heart function. Pulmonary artery banding (PAB) has been reinvented as a possible “regenerative surgery” to retrain the decompensated left ventricle in children with DCM. The rationale is to promote positive ventricular–ventricular interactions that result in recovery of left ventricular function in one out of two children, allowing transplantation delisting. Although promising, global experience with this technique is still limited, and several surgical centers are reluctant to adopt PAB since its exact biological bases remain unknown. In the present review, we summarize the clinical, functional, and molecular known and supposed working mechanisms of PAB in children with DCM. From its proven efficacy in the clinical setting, we described the macroscopic geometrical and functional changes in biventricular performance promoted by PAB. We finally speculated on the possible underlying molecular pathways recruited by PAB. An evidence-based explanation of the working mechanisms of PAB is still awaited to support wider adoption of this surgical option for pediatric heart failure.

Infective endocarditis in an adult with unrepaired corrected transposition

We report a case of a 28-year-old man with unrepaired congenitally corrected transposition of the great arteries, ventricular septal defect, and pulmonary stenosis who presented with septic shock due to infective endocarditis by Abiotrophia defectiva. The cardiac catheterization had the risk of vegetation scattering. Without invasive hemodynamic assessment, the degree of pulmonary stenosis and left ventricle preparation as a systemic ventricle could not be accurately determined, making surgical planning difficult. We chose a staged approach with pulmonary valve replacement first for source control, followed by a more definitive operation following recovery from endocarditis.

Anatomic Repair of Congenitally Corrected Transposition: Reappraisal of Eligibility Criteria

Several criteria to identify suitable candidates for anatomic repair in congenitally corrected transposition (cc-TGA) have been proposed. The purpose of this study was to critically re-evaluate adequacy of these recommendations in our patient cohort. All cc-TGA patients undergoing anatomic repair between 2010 and 2019 were reviewed. Evaluated eligibility criteria for repair included age ≤ 15 years, LV mass index ≥ 45-50 g/m², LV mass/volume ratio > 0.9-1.5 and systolic LV to right ventricle pressure ratio > 70-90% among others. Repair failure was defined as postoperative early mortality or LV dysfunction requiring mechanical circulatory support. Twenty-five patients were included (median [interquartile range] age at surgery 1.8 years [0.7;6.6]; median postoperative follow-up 3.2 years [0.7;6.3]). Median preoperative LV ejection fraction was 60% [56;64], indexed LV mass 48.5 g/m² [43.7;58.1] and LV mass/volume ratio 1.5 [1.1;1.6], respectively. A total of 12 patients (48%) did not meet at least one of the previously recommended criteria, however, all but two patients (92%) experienced favorable early outcome. Of 7 patients (28%) with indexed LV mass < 45 g/m², 6 were successfully operated. There were two early repair failures (8%) with LV dysfunction: one patient died and one required mechanical circulatory support but recovered well. Surgery was performed successfully in patients with LV mass and volume Z-scores as low as - 2 and - 2.5, respectively. Anatomic correction for cc-TGA can be performed with excellent early outcome and is feasible even in patients with LV mass below previously recommended cut-offs. The use of LV mass and volume Z-scores might help to refine eligibility criteria.

Histological changes after pulmonary artery banding for retraining of subpulmonary left ventricle

BACKGROUND

Patients with congenitally corrected transposition of the great arteries (ccTGA) with intact ventricular septum (IVS) or d-looped transposition of the great arteries (DTGA) with IVS post atrial switch operation often develop left ventricular dysfunction after anatomical repair despite prior retraining of the morphologically left ventricle (mLV) using pulmonary artery banding (PAB). We examined histopathological changes in such mLV.

METHODS

Capillary density, myocyte diameter, and interstitial fibrous area in the mLV were retrospectively evaluated in postmortem or explanted heart specimens obtained from patients with ccTGA/IVS or DTGA/IVS post atrial switch operation after PAB for retraining and compared with those of patients with normal cardiac anatomy, ccTGA/IVS or DTGA/IVS without PAB, and ccTGA or DTGA with high mLV pressure using generalized estimating equations models.

RESULTS

Adjusting for age, capillary density in four patients with ccTGA/IVS or DTGA/IVS after PAB was ∼20% lower than that in eight patients with normal cardiac anatomy (3149 ± 863 / um² vs 3978 ± 1206 /um² (mean, SD); p = 0.039), while myocyte diameter was ∼50% larger (16.2 ± 4.0 um vs 11.7 ± 2.4 um (mean, SD); p < 0.001). Interstitial fibrous area did not differ between the two groups (803 ± 422 um² vs 789 ± 480 um², p = 0.92).

CONCLUSIONS

We observed significant cardiomyocyte hypertrophy but lower capillary density in patients with ccTGA/IVS or DTGA/IVS after PAB for retraining compared to normal controls. This suggests inadequate capillary growth is a potential pathological basis for mLV dysfunction occurring after retraining or anatomical repair.

Systematic review and meta-analysis of outcomes of anatomic repair in congenitally corrected transposition of great arteries

BACKGROUND

Treatment of congenitally corrected transposition of great arteries (cc-TGA) with anatomic repair strategy has been considered superior due to restoration of the morphologic left ventricle in the systemic circulation. However, data on long term outcomes are limited to single center reports and include small sample sizes.

AIM

To perform a systematic review and meta-analysis for observational studies reporting outcomes on anatomic repair for cc-TGA.

METHODS

MEDLINE and Scopus databases were queried using predefined criteria for reports published till December 31, 2017. Studies reporting anatomic repair of minimum 5 cc-TGA patients with at least a 2 year follow up were included. Meta-analysis was performed using Comprehensive meta-analysis v3.0 software.

RESULTS

Eight hundred and ninety-five patients underwent anatomic repair with a pooled follow-up of 5457.2 patient-years (PY). Pooled estimate for operative mortality was 8.3% [95% confidence interval (CI): 6.0%-11.4%]. 0.2% (CI: 0.1%-0.4%) patients required mechanical circulatory support postoperatively and 1.7% (CI: 1.1%-2.4%) developed post-operative atrioventricular block requiring a pacemaker. Patients surviving initial surgery had a transplant free survival of 92.5% (CI: 89.5%-95.4%) per 100 PY and a low rate of need for pacemaker (0.3/100 PY; CI: 0.1-0.4). 84.7% patients (CI: 79.6%-89.9%) were found to be in New York Heart Association (NYHA) functional class I or II after 100 PY follow up. Total re-intervention rate was 5.3 per 100 PY (CI: 3.8-6.8).

CONCLUSION

Operative mortality with anatomic repair strategy for cc-TGA is high. Despite that, transplant free survival after anatomic repair for cc-TGA patients is highly favorable. Majority of patients maintain NYHA I/II functional class. However, monitoring for burden of re-interventions specific for operation type is very essential.

Urgent double switch operation in a patient with congenitally corrected transposition of great arteries and an untrained systemic ventricle

Congenitally corrected transposition of the great arteries is a rare cardiac abnormality. A nine-month-old male infant with the diagnosis of congenitally corrected transposition of the great arteries was admitted to our clinic with a history of pulmonary artery banding to train the left ventricle three months ago. On admission, he presented with bronchopneumonia, cyanosis, dyspnea, and severe biventricular heart failure associated with significant valvular regurgitation. An urgent double switch operation was performed with atrial and arterial switch procedures. Eight days of mechanical circulatory support was deemed mandatory following surgery. The patient is still under follow-up uneventfully three years after the operation.

Congenitally corrected transposition of the great arteries

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart lesion with varied morphological presentation and can often by asymptomatic. A failing systemic right ventricle (RV) or increasing tricuspid regurgitation are generally indications for surgical intervention. The surgical approach depends upon the age of the patient and morphology of the lesion. Anatomical correction is associated with satisfactory long-term results.

Pulmonary Artery Banding for Ventricular Rehabilitation in Infants With Dilated Cardiomyopathy: Early Results in a Single-Center Experience

Background: Pulmonary artery banding (PAB) is reported as an innovative strategy for children with end-stage heart failure (ESHF) to bridge to transplantation or recovery. We report our early experience with PAB to evaluate outcomes, indications, and limitations. Materials and Methods: This is a single-center prospective clinical study, including infants and children admitted for ESHF owing to dilated cardiomyopathy (DCM) with preserved right ventricular function after failure of maximal conventional therapy. All patients underwent perioperative anticongestive medical therapy with ACE inhibitor, beta blocker, and spironolactone. Post-operatively, all patients underwent echocardiographic follow-up to assess myocardial recovery. Results: We selected five patients (four males) who underwent PAB at a median age of 8.6 months (range 3.9-42.2 months), with preoperative ejection fraction (EF) <30%. Sternal closure was delayed in all. One patient did not improve after PAB and underwent Berlin Heart implantation after 33 days, followed by heart transplant after 13 months. Four patients were discharged home on full anticongestive therapy. However, 2 months after discharge, one patient experienced severe acute heart failure secondary to pneumonia, which required mechanical circulatory support, and the patient underwent a successful heart transplant after 21 days. The remaining three patients are doing well at home, 22.4, 16.9, and 15.4 months after PAB. They all underwent elective percutaneous de-banding, 18.5, 4.8, and 10.7 months after PAB. EF increased from 17.7 ± 8.5% to 63.3 ± 7.6% (p = 0.03), and they have all been delisted. Conclusion: Use of PAB may be an effective alternative to mechanical support in selected infants for bridging to transplant or recovery. Better results seem to occur in patients aged <12 months. Further experience and research are required to identify responders and non-responders to this approach.

Pulmonary Artery Banding for Congenitally Corrected Transposition of the Great Arteries With Hydrops Fetalis: A Case Report

At 32 weeks of gestation, a male fetus with congenitally corrected transposition of the great arteries developed hydrops fetalis caused by a combination of mitral valve regurgitation and tricuspid valve regurgitation (TR). We performed a pulmonary artery banding (PAB) at 108 days old for gradually progressing TR, after confirming that a balloon dilatation test in the main pulmonary artery reduced TR. As the patient grew, the PAB became tighter and systolic blood pressure in the morphological left ventricle increased. At present, the patient is waiting for a double switch operation.

Congenitally Corrected Transposition Presenting in the First Year of Life: Survival and Fate of the Systemic Right Ventricle

Introduction:

Knowledge gaps exist in the life expectancy and functional outcome of patients with congenitally corrected transposition (ccTGA) presenting early in life, which is relevant in the evaluation of early anatomic repair.

Methods:

In a single-center analysis, 91 patients with ccTGA were identified over 25 years, of which 31 presented with biventricular anatomy in the first year of life and formed the study cohort. End points for analysis included survival, moderate or worse tricuspid valve regurgitation, and systemic right ventricle (RV) dysfunction. Median follow-up was 4.9 years (range: 7 days to 20 years).

Results:

Among 31 patients presenting in the first year of life, 9 (29%) never received cardiac surgery, while 22 (71%) underwent 36 cardiac operations. Overall freedom from moderate or severe systemic RV dysfunction was 75% at 10 years. Overall survival was 82% at 10 years. Surgical mortality was 5.6% (2/36). Among survivors with a systemic RV, 23 (100%) of 23 were Ross or NYHA class I or II at last follow-up.

Conclusions:

Congenitally corrected transposition presenting in the first year of life and maintaining a systemic RV can expect (1) long-term survival of more than 80% at 10 years, (2) low expected surgical mortality (overall 6%), and (3) 75% late freedom from major RV dysfunction at 10 years. Pending multi-institutional analyses, this experience with a systemic RV in ccTGA provides an initial benchmark for comparison when considering early elective anatomic correction.

Congenitally Corrected Transposition of the Great Arteries: Anatomic, Physiologic Repair, and Palliation

Congenitally corrected transposition of the great arteries (ccTGA) is a lesion that rarely occurs in isolation. The presenting physiology of ccTGA is predominantly secondary to the concurrent cardiac lesions; however, as the child ages, unrepaired ccTGA results in progressive failure of the morphologic right ventricle under the strain of maintaining a systemic pressure. Repair of ccTGA was initially focused on rectification of the underlying physiologic aberrations, but in recent years, the focus of repair has shifted toward anatomic correction to avoid failure of the morphologic right ventricle. This anatomic repair is commonly associated with improved long-term mortality at the cost of increased short-term mortality. Key preoperative considerations such as morphologic left ventricular pressure, tricuspid valve competency, and out flow tract obstructions can assist in determining the optimal repair for individual patients. An alternative, single ventricle, pathway has been proposed for any patient without optimal preoperative anatomy to improve long-term survival. Adjunctive repair options including pulmonary artery banding and one-and-a-half ventricle repairs have also been proposed to augment the survival curves.

Contemporary management and outcomes in congenitally corrected transposition of the great arteries

Congenitally corrected transposition of the great arteries (ccTGA) can occur in isolation, or in combination with other structural cardiac anomalies, most commonly ventricular septal defect, pulmonary stenosis and tricuspid valve disease. Clinical recognition can be challenging, so echocardiography is often the means by which definitive diagnosis is made. The tricuspid valve and right ventricle are on the systemic arterial side of the ccTGA circulation, and are therefore subject to progressive functional deterioration. The natural history of ccTGA is also greatly influenced by the nature and severity of accompanying lesions, some of which require surgical repair. Some management strategies leave the right ventricle as the systemic arterial pump, but carry the risk of worsening heart failure. More complex 'double switch' repairs establish the left ventricle as the systemic pump, and include an atrial baffle to redirect venous return in combination with either arterial switch or Rastelli operation (if a suitable ventricular septal defect permits). Occasionally, the anatomic peculiarities of ccTGA do not allow straightforward biventricular repair, and Fontan palliation is a reasonable option. Regardless of the approach selected, late cardiovascular complications are relatively common, so ongoing outpatient surveillance should be established in an age-appropriate facility with expertise in congenital heart disease care.