Background
Atrioventricular discordance with ventriculoarterial concordance, also known as ventricular inversion, is a rare congenital defect. It is characterised by an isolated mismatch between atria and ventricles while maintaining correct arterial connection. The resultant physiology is like that of transposition of the great arteries or a parallel circuit. Van Praagh and Van Praagh first described the different variations of ventricular inversion that can include either normally related or transposed great arteries. Reference Van Praagh and Van Praagh1 Embryonic development informs the recommended echocardiographic imaging technique of sequential segmental analysis to accurately delineate the complex anatomy. Reference Aljemmali, Bokowski and Diab2,Reference Pasquini, Sanders and Parness3 This is the second reported case of prenatally diagnosed isolated ventricular inversion. As expected, our patient required early balloon atrial septostomy, but unexpectedly required urgent patent ductus arteriosus closure in the setting of profound systemic steal.
Case presentation
Our patient was born at 38 w2d via spontaneous vaginal delivery to a Gravida 3 Para 3 mother. Pregnancy was complicated by maternal diabetes, gestational hypertension, and fetal growth restriction. Fetal echocardiogram, performed due to maternal diabetes, raised concern for ventricular inversion with ventriculoarterial concordance. Prenatal genetic studies (Fluorescence in situ hybridization and microarray) did not detect any abnormalities. Following delivery, Appearance, Pulse, Grimace, Activity, Respiration were eight and eight and birth weight was 2.57 kg (6th percentile, small for gestational age). The neonate briefly required supplemental oxygen (FiO2 70%–100%) for desaturations to 60% in the delivery room but was able to maintain oxygen saturations between 85 and 95% in room air by arrival to the neonatal ICU. Postnatal echocardiogram on day of life 1 confirmed the prenatal diagnosis of ventricular inversion of the morphologic right and left ventricles with transposed great arteries (cardiac segments S,L,D). There was atrioventricular discordance with the systemic veins returning normally to the right atrium, which was in continuity with the rightward morphologic left ventricle. The pulmonary veins returned to the left atrium, which was in continuity with the leftward morphologic right ventricle. There was ventriculoarterial concordance with transposed great arteries such that the aorta arose anteriorly from the rightward morphologic left ventricle and the pulmonary artery arose from the leftward morphologic right ventricle (Figures 1–3). The constellation of anatomic findings resulted in transposition physiology. Additional postnatal echocardiogram findings included a large inlet ventricular septal defect, a large unrestrictive patent ductus arteriosus, and a small patent foramen ovale. She initially demonstrated adequate mixing, with saturations in the upper 80s and low 90s in room air, but prostaglandin E1 was initiated to maintain ductal patency and encourage atrial level mixing. On day of life 1, she began to exhibit signs of pulmonary overcirculation and impaired systemic perfusion with high oxygen saturations and lactic acidosis. Repeat echocardiogram showed restriction of the atrial level shunt, partially reflective of additional flow from the large patent ductus arteriosus. Prostaglandin E1 was discontinued, and dopamine and milrinone were initiated to augment cardiac output. Lactate reached a peak of 6.1, but improved, notably with support of higher systemic blood pressure and discontinuation of prostaglandin E1.
Transthoracic echocardiogram 4 chamber view demonstrating atrioventricular discordance with a right sided, morphologic left ventricle and a left sided, morphologic right ventricle. Under image- RA: Right Atrium, LA: Left atrium, LV: Left Ventricle, RV: Right Ventricle.
Transthoracic echocardiogram demonstrating atrioventricular discordance (right atrium to left ventricle) and ventriculoarterial concordance (left ventricle to aorta). Under image-RA: Right Atrium, LV: Left Ventricle, Ao: Aorta.
Transthoracic echocardiogram demonstrating atrioventricular discordance (Left atrium to right ventricle) and ventriculoarterial concordance (right ventricle to pulmonary artery. Under image- MPA: Main pulmonary artery, RA: Right atrium, LA: Left atrium, RV: Right ventricle.
On day of life 2, with improved lactate and clinical stability, she underwent a successful balloon atrial septostomy in the cardiac catheterisation lab with creation of a large, unrestrictive atrial septal defect. Following the procedure, she continued to exhibit signs of significant pulmonary overcirculation and impaired systemic perfusion with high oxygen saturations, decreased cerebral and renal near infrared spectroscopy, acute kidney injury, and progressive lactic acidosis. She was supported with mechanical ventilation, sedation, neuromuscular blockade, milrinone infusion, packed red blood cell transfusion, and diuretic therapy, and subsequently had a transient period of clinical improvement.
By day of life 4, it became clear that her large patent ductus arteriosus was continuing to promote pronounced pulmonary overcirculation and systemic steal despite escalation in medical management, and thus she was referred for urgent transcatheter patent ductus arteriosus closure. Angiographically, the patent ductus arteriosus was a large, Type E ductus and measured 6.9 mm at the aortic end, 4 mm on the pulmonary artery end, and 7.2 mm in length. It was closed with a 6/6 mm Amplatzer Vascular Plug Type II via 4 Fr sheath from the right femoral artery. Following closure of the patent ductus arteriosus, she was noted to have immediate haemodynamic improvement with an increased systemic blood pressure, narrower pulse pressure, heart rate normalisation, 20-point increase in renal near infrared spectroscopy, and brisk urine output.
She was extubated 2 days post-procedure and able to quickly wean from non-invasive respiratory support. She remained haemodynamically stable without inotropic support and tolerated enteral feed advancements. Serial echocardiograms demonstrated more balanced physiology, and she maintained goal saturations >75%. The patient continued to require Lasix, in the setting of large ventricular septal defect, during the remainder of the hospitalisation and following discharge.
The patient was readmitted for planned, uncomplicated gastrostomy tube placement at 3 months of age. Following the procedure, she was noted to have progressive cyanosis with more frequent and severe desaturations, so she remained hospitalised until her cardiac repair. At 4 months of age, she underwent an uncomplicated cardiac surgery, consisting of ventricular septal defect patch closure and atrial switch operation (Senning procedure). Her postoperative course was uncomplicated aside from a slow junctional rhythm early postoperatively that required transient pacing. She was extubated on postoperative day 2 and progressed as expected towards discharge on postoperative day 11. She has continued to do well in the outpatient setting. Her most recent echocardiogram, 5 months postoperatively, demonstrated an unobstructed intra-atrial baffle and normal biventricular size and function. She is growing and developing normally. She continues to be followed by our feeding team to improve oral feeding.
Discussion
Our patient’s particular congenital cardiac anatomy, atrioventricular discordance with ventriculoarterial concordance, occurs rarely. To our knowledge, there has been only one other case report of prenatal diagnosis of this anomaly. The authors who previously described similar cases express the importance of prenatal or early diagnosis, when able, to plan and execute appropriate perinatal management strategies. Reference Aljemmali, Bokowski and Diab2,Reference Nguyen, Dinh and Ly Nguyen4 Management across the other reported cases exhibits the critical aspects of maintaining ductal patency with early initiation of prostaglandin E1 to promote extra-cardiac mixing and ensuring adequate atrial level mixing with balloon atrial septostomy, as palliative measures prior to the corrective atrial switch. The Senning procedure, or atrial switch, is unique in that it anatomically corrects isolated ventricular inversion, given the ventriculoarterial concordance, which maintains the left ventricle as the systemic ventricle. Reference Hermsen, Okorie, Srinivasan, Schreiter and Anagnostopoulos5
Our case was unique compared to other reported cases of similar anatomy because our patient exhibited profound pulmonary overcirculation and systemic steal in the setting of a large patent ductus arteriosus. Interestingly, in other reported cases, patients have required placement of patent ductus arteriosus stents to maintain ductal patency and ensure adequate mixing. This wide variation in clinical presentation demonstrates the delicate and largely unpredictable balance of maintaining adequate mixing of oxygenated and deoxygenated blood while recognising the potential alterations of pulmonary and systemic blood flow as a result of actions taken to promote mixing.
In summary, prenatal diagnoses of rare congenital cardiac conditions allow for critical perinatal planning and effective patient management. Reference Nguyen, Dinh and Ly Nguyen4 Atrioventricular discordance with ventriculoarterial concordance is rare but can be diagnosed prenatally and managed carefully with palliative strategies prior to total anatomic correction with the Senning procedure. Postnatal care teams must be vigilant to understand the patient’s physiology, as it can vary widely among patients with similar anatomy.
