Dual-Drainage Infradiaphragmatic TAPVR With Splenic Venous Connection

Abstract

Background

Infradiaphragmatic total anomalous pulmonary venous return (TAPVR) is an uncommon subtype of anomalous pulmonary venous drainage; dual, nonconfluent pulmonary venous pathways are extraordinarily rare. Such atypical configurations increase the complexity of diagnosis and operative planning, requiring meticulous anatomic evaluation in critically ill neonates.

Case Summary

A term 2-day-old neonate presented with hypoxemic respiratory failure and pulmonary congestion with suspected infradiaphragmatic TAPVR. Emergent repair revealed a right-sided confluence draining via a vertical vein with a blind connection to the left atrium; the left pulmonary veins were not visualized. Postoperative computed tomography demonstrated a separate left-sided confluence draining into the splenic vein. Although initially unobstructed, progressive narrowing led to readmission and redo sternotomy with sutureless anastomosis to the left atrium. The patient recovered with unobstructed bilateral pulmonary venous return and decreased right ventricular pressures.

Discussion

Dual, nonconfluent infradiaphragmatic TAPVR in a biventricular heart is exceptionally rare. This case highlights the limitations of echocardiography and the essential role of cross-sectional imaging in delineating complex venous anatomy.

Take-Home Messages

Despite optimal echocardiography, there is always some degree of uncertainty regarding total anomalous pulmonary venous return anatomy. If risks are acceptable, efforts should be made to obtain advanced imaging for preoperative management and surgical planning.

Visual Summary

Obstructive total anomalous pulmonary venous return (TAPVR) is a critical congenital heart defect in which all pulmonary venous drainage enters the systemic venous circulation rather than the left atrium. When the anomalous pathway is stenotic or extrinsically compressed, severe hemodynamic compromise rapidly develops. TAPVR is classified using the Darling system based on the site of drainage and includes the following: supracardiac (type I), cardiac (type II), infracardiac or infradiaphragmatic (type III), and mixed type (type IV).¹ Type III TAPVR accounts for approximately 13% to 25% of cases and is characterized by a descending vertical vein traversing the diaphragm to join the inferior vena cava, hepatic veins, portal system, or umbilical venous system.² Infradiaphragmatic TAPVR presenting with obstruction carries the worst prognosis among subtypes.³ Cases of 2 nonconfluent infradiaphragmatic pulmonary venous pathways are extremely rare and have previously been described only in single ventricle patients with right atrial isomerism.⁴ We present the first case, to our knowledge, of a 2-day-old, 3.3-kg term neonate with obstructive TAPVR who underwent emergent repair and was subsequently found on postoperative imaging to have dual right- and left-sided venous confluences draining through separate infradiaphragmatic vertical veins.

Take-Home Messages

• •Despite optimal echocardiography, there is always a degree of uncertainty regarding total anomalous pulmonary venous return anatomy.
• •When risks are acceptable, advanced imaging should be obtained to guide preoperative management and surgical planning.

Clinical Summary

A 2-day-old, term neonate was transferred to our institution for hypoxemic respiratory failure shortly after birth, requiring increasing continuous positive airway pressure (8 cm H₂O) and fraction of inspired oxygen of 100%. Initial vital signs included saturation 87% to 92%, heart rate 120 beats/min, and blood pressure 78/40 mm Hg. Delivery was complicated by meconium-stained amniotic fluid, raising suspicion for meconium aspiration. A preductal/postductal saturation difference of >10% was noted. Blood gas analysis revealed respiratory acidosis (pH: 7.18, Pco₂: 50s-70s), prompting initiation of inhaled nitric oxide at 20 ppm.

Chest radiograph showed diffuse interstitial and hazy alveolar opacities with a small right pleural effusion (Figure 1A). Initial echocardiography suggested 4 pulmonary veins converging posteriorly into a common confluence with a large vertical vein descending below the diaphragm (Figures 1B to 1D). Pulse Doppler demonstrated a highest mean gradient of 5 mm Hg. The atrial septum was markedly thickened with a sprung patent foramen ovale vs an atrial septal defect, with the septum primum bowing right to left with continuous unobstructed right to left shunting. The right ventricle was severely dilated with normal systolic function, whereas the left ventricle appeared underfilled with normal function. A small patent ductus arteriosus demonstrated bidirectional flow.

Figure 1.

Preoperative Chest Radiograph and Echocardiogram (Suprasternal View)

(A) Chest radiograph showing diffuse pulmonary edema characteristic of obstructed infradiaphragmatic total anomalous pulmonary venous return. (B) Right superior and inferior pulmonary veins and right inferior pulmonary vein entering a common pulmonary venous confluence (yellow arrow). (C) Left superior and inferior pulmonary veins entering confluence (green arrow). (D) Perceived confluence of pulmonary veins (red arrow). LIPV = Left Inferior Pulmonary Vein; LSPV = Left Superior Pulmonary Vein; RIPV = Right Inferior Pulmonary Vein; RSPV=Right Superior Pulmonary Vein.

Management

Given concern for critical obstructive physiology and unstable respiratory status, the patient was taken for emergent surgical repair. Cardiopulmonary bypass (CPB) was established via aorto-right atrial cannulation with cooling to 18 °C. Intraoperatively, a posterior pulmonary venous confluence was identified near the diaphragm. The right pulmonary veins drained into a confluence communicating with a blind pouch on the posterior left atrial wall; however, the left-sided pulmonary veins could not be located. The confluence continued inferiorly with 2 small caliber branches coursing along the left side of the spine with unclear origin (Figure 2C). After achieving target hypothermia, the aorta was cross clamped and cold crystalloid cardioplegia was administered for circulatory arrest. The observed descending vertical vein was ligated after confirming no additional venous drainage below the diaphragm. The confluence was opened, and a counter incision was made in the posterior left atrium. The right atrium was opened and the atrial septum inspected. A thickened septal area was excised, corresponding to the blind pouch connecting to the confluence. The left atrial edge was sutured to the venous confluence along the left side of the spine due to the extensive dissection required to identify the left-sided veins. A sutureless approach was used to sew the right side. The atrial septal defect was closed with a patch of bovine pericardium, leaving a 2.5-mm fenestration. CPB, circulatory arrest, and cross-clamp times were 158, 56, and 70 minutes, respectively.

Figure 2.

Advanced Imaging, 3D Reconstruction, and Anatomical Illustration

(A) Post operative coronal computed tomography (CT) showing vertical vein (yellow arrow) from left pulmonary vein draining into splenic vein (B) Post operative CT 3-dimensional reconstruction showing left pulmonary vein draining into infradiaphragmatic vertical vein (red arrow). (C) Schematic from intraoperative observation, CT imaging, and echo findings revealing dual infradiaphragmatic vertical veins. Preoperative echo suggested a common confluence with a large vertical vein descending below the diaphragm with a highest mean gradient of 5mmHg. (D) Preoperative CT 3-dimensional reconstruction showing remaining left pulmonary infradiaphragmatic vertical vein. (E) Status post repair of TAPVR with right and left pulmonary veins draining into the left atrium.

Outcome and Follow-Up

Postoperatively, the patient required low-dose inotropes and mechanical ventilation. Given the unusual intraoperative findings with inability to find the left-sided veins, a cardiac computed tomography (CT) scan was obtained. Imaging revealed the left pulmonary veins forming a separate confluence with an infradiaphragmatic course draining into the splenic vein (Figures 2A to 2C). Follow-up echocardiography demonstrated unobstructed right pulmonary venous flow into the left atrium, and low-gradient antegrade flow (1-2 mm Hg) through the left-sided infradiaphragmatic pathway without obstruction. The patient was extubated on postoperative day 13, weaned to room air by day 21, and discharged on day 23 with adequate weight gain and feeding tolerance. At 2 months of age (4.5 kg), she was readmitted with increased oxygen requirements and respiratory distress. Transthoracic echocardiography demonstrated a left-sided infradiaphragmatic vertical vein with narrowing (5 mm Hg) to 1.4 mm at the level of the diaphragm, with worsening right ventricular dilation and elevated right-sided pressures. The patient subsequently underwent redo median sternotomy with sutureless anastomosis of the left pulmonary venous confluence to the left atrium. Postoperative imaging demonstrated unobstructed bilateral pulmonary venous return with improvement in right ventricular pressures, and the patient has remained clinically stable since discharge (Figures 2D and 2E).

Discussion

Obstructed infradiaphragmatic TAPVR constitutes a life-threatening neonatal emergency because venous obstruction rapidly leads to severe pulmonary hypertension, hypoxemia, and metabolic acidosis. In this case, acidosis, impending respiratory failure, radiographic pulmonary congestion, and gradient across the descending vertical vein necessitated immediate surgical intervention. The presence of 2 nonconfluent infradiaphragmatic pulmonary venous pathways in a structurally normal biventricular heart is exceptionally rare. Intraoperative findings included a right-sided confluence with a blind connection to the left atrium and a vertical infradiaphragmatic vein. The left pulmonary confluence, draining inferiorly into the splenic vein, was not visualized during surgery. Similar dual drainage systems have been described almost exclusively in patients with heterotaxy and right atrial isomerism.⁴

This case underscores the limitations of preoperative echocardiography in defining complex posterior and infradiaphragmatic anatomy. A recent single-center study evaluating anatomic accuracy found that 9% of patients (15/167) had incorrect subtype diagnosis on initial echocardiogram.⁴ This highlights the importance of systematically tracing the entire path of the pulmonary venous drainage pathway, using appropriate transducers, optimizing color Doppler gain, and obtaining adequate subcostal and suprasternal views.¹ When echocardiography is inconclusive, CT or magnetic resonance imaging should be pursued for precise anatomic delineation, particularly when mixed or atypical venous drainage is suspected. In this patient, postoperative CT was crucial for identifying persistent anomalous drainage of the left pulmonary veins and later for confirming progressive narrowing before reintervention. Although initially unobstructed, infradiaphragmatic venous pathways draining into the portal circulation are particularly susceptible to progressive narrowing due to diaphragmatic compression or elevated portal venous resistance.^2,5 This anatomy places the patient at increased risk for recurrent pulmonary venous obstruction, most common in infracardiac and mixed TAPVR. In a retrospective cohort of 768 patients, risk factors for recurrent obstruction included preoperative obstruction, infradiaphragmatic drainage, mixed variants, and prolonged CPB time.⁶ Because early gradients may be low, close surveillance with serial echocardiography and cross-sectional imaging is appropriate, with definitive repair reserved for clinical decompensation, rising gradients, or worsening right ventricular pressures. In this case, progressive hypoxemia and documented anatomic narrowing prompted reintervention at a time when somatic growth allowed for safer and more definitive reconstruction.

Conclusions

This case illustrates an exceptionally rare form of dual, nonconfluent infradiaphragmatic TAPVR with persistent left pulmonary venous drainage into the splenic vein. It highlights the diagnostic challenges inherent to neonatal TAPVR, the importance of intraoperative vigilance, and the indispensable role of postoperative cross-sectional imaging when anatomy remains uncertain. Ongoing surveillance with echocardiography and consideration of cross-sectional imaging is essential given the potential for progressive obstruction of the unrepaired left-sided venous pathway and the need for subsequent surgical planning.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Visual Summary.

Clinical Course

Timeline	Events
Day 2 of life	Term neonate presented with hypoxemic respiratory failure requiring escalating support (CPAP, Fio2: 1.0). Notable >10% preductal/postductal saturation difference. Blood gas demonstrated respiratory acidosis.
	Chest radiograph showed bilateral diffuse interstitial and alveolar opacities consistent with pulmonary edema.
	Transthoracic echocardiography suggested infradiaphragmatic TAPVR with a descending vertical vein (mean gradient: 5 mm Hg), severely dilated right ventricle, and underfilled left ventricle. Inhaled nitric oxide initiated.
Operative repair	Emergent repair via median sternotomy. Right-sided pulmonary venous confluence identified and anastomosed to the left atrium. Left pulmonary venous return not visualized intraoperatively, despite extensive dissection.
Early postoperative period	Cardiac CT demonstrated a second, distinct left-sided pulmonary venous confluence draining via an infradiaphragmatic vertical vein into the splenic vein (initially unobstructed).
POD 13	Successfully extubated.
POD 23	Discharged home on room air with adequate oral intake and weight gain.
2 mo of age	Readmitted with increased work of breathing and new oxygen requirement.
	Echocardiography showed progressive obstruction of the unrepaired left-sided vertical vein (mean gradient: 5 mm Hg), with worsening right ventricular dilation and elevated right-sided pressures.
Operative repair 2	Redo median sternotomy with division of infradiaphragmatic anomalous pulmonary venous pathway and extended sutureless anastomosis of the left pulmonary venous confluence to the left atrium/left atrial appendage.
Postoperative course
POD 7	Successfully extubated.
POD 17	Discharged home in stable condition.
30-d follow-up	Asymptomatic with appropriate growth and room air saturations. Echocardiography demonstrated unobstructed bilateral pulmonary venous drainage with improved right ventricular size and pressures.

CPAP = continuous positive airway pressure; CT = computed tomography; Fio₂ = fraction of inspired oxygen; POD = postoperative day; TAPVR = total anomalous pulmonary venous return.