Impact of hybrid procedure on pulmonary arterial dimensions and right ventricular load after biventricular repair

Patient selection

Between 2010 and 2021, we identified 5 patients with complex congenital heart defect with interrupted aortic arch who underwent hybrid procedure and staged biventricular repair (“hybrid group”). These cases were statistically compared with 7 cases with interrupted aortic arch and immediate aortic repair in the newborn age (“non-hybrid group”). This study was performed as single center retrospective study at the University of Heidelberg, Germany and was approved by the local institutional ethic committee (S-224/2013, 20.12.2018) in accordance to the declaration of Helsinki and with consent of patient´s caregivers. Cases with univentricular palliation (e.g. hypoplastic left heart syndrome) were excluded from this study.

In literature, different risk scores were published to predict anatomic suitability for biventricular repair in neonates with aortic stenosis evaluating left ventricular dimensions, diameter of aortic valve and left ventricular outflow tract as well as aortic arch dimensions. We used Rhodes score [6], CHSS-1 [7], CHSS-2 [8] and Discriminant score [9] to compare anatomic complexity of left heart structures in our patient population as described in detail in literature.

The indication to surgical procedure (hybrid procedure versus immediate repair) was provided on individual patient´s case and in consent of pediatric and surgical team. Following indications existed in the hybrid-group: Patient 1: neonatal sepsis and intracardiac pathology with left ventricular outflow tract obstruction, hypoplastic aortic valve and ascending aorta, ventricular septal defect. Patient 2: neonatal sepsis, pulmonary steal with impaired perfusion of lower body and necrotizing enterocolitis. Patient 3: intracardiac pathology with left ventricular outflow tract obstruction, hypoplastic aortic valve and ventricular septal defect, persistent cardiac failure after reducing and re-escalation of prostaglandine-thearpy. Patient 4: cardiac failure with need of catecholaminergic treatment, pulmonary steal with impaired perfusion of lower body. Patient 5: premature hypotrophic twin with relevant intraventricular hemorrhage with recurrent seizures.

Surgical and interventional procedures

Surgical and interventional approach for hybrid procedure and biventricular repair were investigated as well as interventional and surgical treatment on pulmonary vessels during follow up.

Bilateral pulmonary artery banding

Bilateral pulmonary artery banding (bPAB) was performed via a median sternotomy and a partial upper pericardiotomy. Both pulmonary arteries were banded to a diameter of 3.5 mm using PTFE (polytetrafluorethylene) bands as described previously [10]. The pericardium was completely closed after extensive irrigation with saline.

Ductal stent placement

Stenting of the patent ductus arteriosus (PDA) was performed percutaneous via catheter-intervention. Depending on the anatomical features of the PDA and vascular access (aortic, pulmonary), either pre-mounted balloon-expandable (Cordis® Genesis 10 × 19 mm, Terumo® Tsunami 6 × 18 mm) or self-expandable stents (Optimed® Sinus superflex DS, Germany, 7 × 20 mm, 7 × 15 mm) were implanted.

Percutaneous balloon-angioplasty of pulmonary arteries

After hemodynamic measurement and angiography of the pulmonary stenosis, a guidewire was delivered into the pulmonary artery and a balloon-angioplasty catheter was positioned (e.g. Cordis Powerflex® Pro PTA Dilatation catheter). Dilatation was performed between two to four time depending on interventional effect on the vessel. Paravasat was excluded by postinterventional angioplasty. For catheter based-intervention, femoral access was preferred.

Aortic arch reconstruction

After sternotomy and dissection of the heart and surrounding structures, cardiopulmonary bypass was established using arterial cannulation either directly in the aorta, the innominate artery or using a 3.5 mm PTFE-Shunt anastomosed to the innominate artery. An additional arterial cannula was placed in the PDA. The pulmonary artery bands were removed. After cooling to 18 to 24 °C, cardioplegic arrest was initiated. The VSD was usually approached using a transatrial approach and closed with xenopericardium using running sutures. The PDA was ligated and excised on the pulmonary side. If needed, the pulmonary bifurcation including the previous banding sites were now reconstructed using patch augmentation with equine xenopericardium (Matrix, AutoTissue, Berlin, Germany). For aortic arch reconstruction, either selective cerebral perfusion or deep hypothermic circulatory arrest was applied. The remnant stent material on the aortic site and all ductal tissue was removed. The descending aorta was now extensively mobilized and anastomosed with the proximal end of the aortic arch. Usually, the posterior wall was amenable to direct anastomosis while the anterior wall was augmented using homograft patch material.

Invasive and non-invasive diagnostics

Non-invasive and invasive diagnostic procedures were performed with medical indication and retrospectively reviewed to investigate dimensions and function of the left ventricle as well as pulmonary arterial diameter and right ventricular pressure.

As additional follow up parameters survival, body weight and length, as well as echocardiographic marker for left ventricular dimensions and systolic function were investigated. Doppler measurement of maximal systolic velocity in der distal aortic arch was used as assessment for aortic pressure gradients. For diameter of left and right pulmonary artery, z-scores from Daubeney et al. were used [11]. To assess left ventricular outflow tract obstruction, we used calculation of Hirata et al., with cut-off of aortic valve annulus diameter in mm higher than body weight in kilogram + 1,5 [12]. Nakata index and lower lobe index were calculated as described in detail elsewhere [13,14,15].

Statistical analysis

Statistical analysis and graphs were performed with OriginPro 2019. In text, absolute values are given as mean ± standard deviation and 95% coincidence interval (CI) as mentioned. Statistical analysis of two groups was performed by students t-test with P < 0.05 defined as significant. Box plot data is shown as median value as line with mean value as unfilled square and box as interquartile range. Whiskers indicate minimum and maximum range; black diamond-shaped dots show outliers. Bar graphs show mean value as bar with black diamond-shaped dots as single data point and whisker as minimum and maximum range. For equality test in Kaplan–Meier curve, log-rank test was performed with P < 0.05 defined as significant.

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