Surgical Approach to Partial and Total Anomalous Pulmonary Venous Connection 

Updated: Jan 30, 2015
Author: Nicola Viola, MD; Chief Editor: Stuart Berger, MD 

Overview

Background

Anomalous congenital connections of the pulmonary venous system represent a spectrum of conditions in which the pulmonary veins are partially or entirely connected to the right atrium, either directly or via the systemic venous return. Anomalous connection rather than “drainage” or “return” better describes the anatomical situation.

History of the Procedure

Wilson first described the analogy in 1798, which Brody reviewed in 1942 (37 cases in the literature). Muller performed the first surgical intervention in 1951, and the condition was first completely corrected with the use of cardiopulmonary bypass in 1956-1957.

Since then, various modifications of the technique have been proposed. For instance, free and in situ autologous tissue have been used to create a wide, unobstructed connection between the pulmonary venous confluence and the left atrium (LA). Despite this technique, 10-15% of patients represent with stenosis after initial successful correction. Recurrent stenosis is often a progressive process, resulting in multiple representations requiring further procedures for correction, with an increasingly poor outcome at each representation.

Most recently, a technique to minimize the surgical trauma to the pulmonary vein intima was proposed to improve outcomes in patients with postrepair stenosis. At present, indications for using this technique are being extended to the correction of primary venous anomalies.

Problem

In the absence of a normal connection, an alternative pathway is formed to allow the egress of blood from the developing lung. This connection is usually to the right atrium (RA), or a systemic vein draining into the RA, thus creating a left-to-right shunt.

Patients with partial anomalous pulmonary venous connection (PAPVC) most commonly have an associated sinus venosus type atrial septal defect (ASD).

Patients with total anomalous pulmonary venous connection (TAPVC) most commonly present a confluence draining into a connecting vein to the systemic venous system. Less commonly, the pulmonary veins may drain to multiple sites (mixed pulmonary venous connection). Supply of oxygenated blood to the systemic circulation relies on an intracardiac right to left shunt in these patients.

Epidemiology

Frequency

TAPVC and PAPVC account for 1-2% of congenital heart defects.

Etiology

The primitive lungs buds out-pouch from the foregut at 26-27 days' gestation. Shortly after a venous splanchnic plexus develops around them and allows the drainage of blood into the anterior cardinal (the later vena cava, coronary sinus, and azygous vein) and into the umbilicovitelline (ie, portal system) systems. Around day 27, the primordial pulmonary vein arises behind the developing atrium and fuses with the splanchnic plexus, around day 30. The portion of the atrium to the left of the developing septum primum then fuses with the pulmonary venous confluence positioned behind it as a result of the reabsorption of the primordial vein. By day 38-40, the reabsorption is complete and 4 distinct pulmonary vein ostia are found on the posterior wall of the fully formed left atrium. At the same time, the connections between the lung buds and the systemic venous system regress.

TAPVCs are thought to result from failure of fusion between the LA evagination and the pulmonary venous plexus or from a position mismatch between the atrial evagination and the forming atrial septum. PAPVCs occur at the same stage but do not involve all 4 veins.

Anomalies occurring at a later stage and in particular during the reabsorption of the primordial vein are at the origin of related lesions like cor triatriatum and atresia of pulmonary vein. Anomalies in the modality of formation and involution of the primordial pulmonary vein are responsible for rarer conditions like congenital pulmonary vein stenosis and an abnormal number of pulmonary veins.[1, 2]

Pathophysiology

Partial anomalous pulmonary venous connection

The main hemodynamic abnormality is represented by the left-to-right shunt imposed by pulmonary venous drainage into the RA. The presence of an interatrial communication further increases the left to right shunt because as much as 50% of the total venous return to the left atrium can shunt to the right side. The resulting volume overload leads to chronic dilatation of the right ventricle, hypertrophy, and, eventually, supraventricular arrhythmias and systolic dysfunction.

Although an ASD usually produces a left-to-right shunt, it adds the potential for right-to-left shunting at a later stage when pulmonary hypertension and right ventricular diastolic dysfunction ensue.

Total anomalous pulmonary venous connection

The hemodynamic abnormality in patients with TAPVC is related to the complete diversion of pulmonary venous blood away from the left atrium to a systemic vein. As a consequence, 2 anatomic factors determine the patient's clinical status.

An obstruction may occur in the path of the pulmonary venous drainage from the lungs to the systemic venous system. If obstruction occurs, egress of blood from the lungs is limited. The consequences of obstruction are pulmonary venous congestion, pulmonary hypertension with consequent limitation of pulmonary blood flow, increased right atrial pressures, hypoxia, and low cardiac output. These events lead to life-threatening cyanosis and shock immediately after birth.[3]

Desaturated blood cannot reach the left ventricle unless a right-to-left shunt is present. In most cases, this is a patent foramen ovale (PFO), ASD, or, more uncommonly, a patent ductus arteriosus (PDA) or ventricular septal defect (VSD). The obligated right-to-left shunt determines systemic cardiac output and oxygenation.

Presentation

Partial anomalous pulmonary venous connection

Patients are often asymptomatic and present with a murmur as an incidental finding upon routine examination. Older patients may present with primary arrhythmia, most commonly atrial fibrillation.

Subsequent workup demonstrates PAPVC and an associated sinus venosus ASD. Symptomatic patients present with the sequelae of a large left-to-right shunt: decreased exercise tolerance and/or poor growth. Upon examination, cyanosis is rarely seen unless pulmonary hypertension has developed. A fixed-split and prominent second heart sound and a functional systolic murmur at the left parasternal upper auscultation point are often present.[4]

Total anomalous pulmonary venous connection

The degree of pulmonary venous obstruction largely determines the clinical presentation. Patients with high-grade obstruction present perinatally with profound cyanosis and shock, or with cyanosis, respiratory distress, and poor growth in mildly stenosed circulation. Upon examination, tachypnea, cyanosis, and poor peripheral perfusion are invariably seen. The second heart sound is prominent and split as a result of pulmonary arterial hypertension. Unless rapid resuscitation measures including intubation and early surgical repair are put in place, death is the likely outcome in these cases.

In contrast, patients without clinically significant pulmonary venous obstruction present in infancy or early childhood with signs and symptoms related to a large left-to-right shunt and resulting right-heart volume overload. They still can present with dyspnea, poor feeding, and poor growth. They may have cyanosis on examination, but this is usually mild.

Indications

Obstruction in the pulmonary venous pathway constitutes a surgical emergency in patients with total anomalous pulmonary venous connection (TAPVC). Medical measures aim at resuscitating and optimizing the patient's clinical status until definitive repair and include intubation, hyperventilation with 100% oxygen, prostaglandin infusion, aggressive correction of pH, correction of all metabolic dysfunction, and inotropic support. The definitive therapeutic goal is complete relief of pulmonary venous obstruction and correction of the anomalous correction, which can be accomplished with only surgical repair.

In the absence of obstruction, surgery can be performed on an elective basis after diagnosis. Excellent clinical results are reported in infants, suggesting that little is gained by delaying surgical repair beyond age 4-6 months.

Relevant Anatomy

Partial anomalous pulmonary venous connection (PAPVC) is characterized by the failure of 1-3 pulmonary veins to incorporate within the developing left atrium (LA). Typically, the right upper pulmonary vein (RUPV) is affected and connects to the superior vena cava (SVC), most commonly at the SVC–right arterial (RA) junction (see the image below).

Partial anomalous pulmonary venous connection (PAP Partial anomalous pulmonary venous connection (PAPVC) of right-sided pulmonary veins to the right superior venoatrial junction. Note the enlarged confluence and superior vena cava. SVC = Superior vena cava; IVC = Inferior vena cava; RUPV = Right upper pulmonary vein; RMPV = Right middle pulmonary vein.

More infrequently, the junction is at higher levels above the inlet of the azygos vein. Occasionally, the connection is found at the SVC-innominate vein junction. Less frequently, the lower pulmonary vein connects to the inferior vena cava (IVC)–RA junction. In some rare instances, both veins connect to the right atrial wall.[5, 6]

This lesion commonly occurs in association with sinus venosus atrial septal defect (ASD), which can be found above the superior limbus or below the fossa ovalis (beneath the Valsalva valve). Intact atrial septum is rare.

A more serious condition albeit rare is the scimitar syndrome, where the whole of the right lung veins drain into the IVC via a long vein descending parallel to the right-heart border (see the image below).

(A): Patient with obstructed scimitar syndrome (ma (A): Patient with obstructed scimitar syndrome (magnetic resonance angiography). The right upper pulmonary vein (RUPV) is diffusely narrow and presents a discrete stenosis at the confluence with the right lower pulmonary vein (red arrow). (B): The confluence at the atrial level appears unobstructed (white arrow) in the 3D reconstruction.

The radiographic appearance of an enhanced vertical profile, resembling the blade of a scimitar sword is the diagnostic finding in these cases. This condition is commonly associated with right lung hypoplasia, aortopulmonary collaterals to the right lung, pulmonary venous obstruction, and pulmonary hypertension.[7]

In patients with total anomalous pulmonary venous connection (TAPVC) lungs drain to the systemic venous system, creating a large left-to-right shunt. Supply of oxygenated blood to the systemic circulation requires an intracardiac communication. This communication is usually an ASD, less commonly a patent ductus arteriosus (PDA), or ventricular septal defect (VSD). Any obstruction at the level of the confluence, communicating vein, or the intracardiac shunt results in decreased left side blood inflow, pulmonary venous congestion, and consequent pulmonary hypertension.[8]

TAPVC represent a wide array of venous configurations. A unified nomenclature system has been presented at the International Nomenclature and Database Conferences for Pediatric Cardiac Surgery.[9] In this system, the original Darling's classification has been adopted because of its simplicity and wide acceptance, but the presence or absence of obstruction has been added, as well as the nature and level of obstruction. Four types are therefore identified, all of which can present with or without obstruction (see the image below).

Types of total anomalous pulmonary venous connecti Types of total anomalous pulmonary venous connection.

The supracardiac type accounts for 45-55% of cases (see the image below).

(A): Total anomalous pulmonary venous connection ( (A): Total anomalous pulmonary venous connection (TAPVC) of supracardiac type. All pulmonary veins drain into a long confluence and a short communicating vein is attached to the right superior vena cava (SVC). The left lower pulmonary vein appears stenosed (red arrow). (B): These findings are confirmed by the 3D reconstruction (white arrow).

All 4 veins connect to a confluence positioned behind the left atrium, from which a communicating vein (vertical vein) ascends inside or outside the pericardial cavity to connect with the systemic venous system. The innominate vein, the right sided SVC or a persistent left-SVC represent the usual sites of insertion. Obstruction in this type is uncommon. When present, obstruction can result from a so-called anatomical vice where the connecting vein is compressed between the left pulmonary artery and the left bronchus. Given the restriction to the egress of blood from the lungs, pulmonary arterial pressure rises, causing further distension of the pulmonary artery, thus promoting a vicious cycle of distension-obstruction.

In the cardiac group (15-20%), the pulmonary venous confluence connects to the coronary sinus. This can be direct or by interposition of a short connecting vein. The coronary sinus is invariably enlarged, and in some cases is unroofed. Rarely the confluence drains directly to the right atrium. Obstruction in this type is uncommon, but stenosis of the short connecting vein to the coronary sinus has been reported.

Infracardiac types account for 15-20% of cases. Most commonly a vertical vein lying posteriorly to the pericardium connects the pulmonary vein confluence with the portal veins, or the ductus venosus, after traversing the diaphragm through the oesophageal hiatus. Blood then enters the right atrium via the inferior vena cava (IVC). The course of the connecting vein is often long and tortuous, resulting in a high incidence of obstruction which can result from external compression or be of intrinsic nature.

In the mixed type (5-10%), pulmonary venous drainage occurs with a combination of supracardiac, cardiac, and/or infracardiac connections.

Shunts at an atrial level are typically of adequate size and the interatrial gradient is usually low. Restrictive flow across the intracardiac communication is uncommonly the cause of obstruction but when present produces a severe compromise of systemic cardiac output. Moreover, any restriction at the level of the ASD, reducing the volume of blood able to cross to the left heart, causes elevation of the RA pressure and functional obstruction of the pulmonary venous return.[10]

The LA is generally half the size of the expected normal, due to a small posterior component. In most cases the left ventricle has normal size and muscular mass. On the contrary, the right ventricle can be enlarged and hypertrophied, especially in supradiaphragmatic, nonobstructive lesions.[11]

As many as 90% of patients with heterotaxy and asplenia have TAPVC. Tetralogy of Fallot, double outlet right ventricle, and interrupted aortic arch have also been reported as associated lesions[12, 13] .

Contraindications

Total anomalous pulmonary venous connection

No specific contraindications are noted for the repair of total anomalous pulmonary venous connection (TAPVC), although the surgical risk may be high in select groups of patients (eg, single ventricle, or heterotaxy syndromes).

Partial anomalous pulmonary venous drainage

In patients with partial anomalous pulmonary venous drainage (PAPVC) and an atrial septal defect (ASD), closure of the ASD may be inappropriate when pulmonary artery pressures are greater than two thirds the systemic pressure. Although rare, the presence of irreversible pulmonary hypertension is associated with systemic cyanosis. The surgical risk in this group of patients may be prohibitive.

 

Workup

Laboratory Studies

ABG values, including pO2, pCO2, pH, base excess, lactate concentration, and mixed venous oxygen saturations permit quantitative assessment of the patient's oxygenation and systemic perfusion. Acute ABG evaluation assists in the resuscitation of a neonate with obstructed total anomalous pulmonary venous connection (TAPVC). Severe metabolic acidosis and hypoxemia are often seen.

Hematocrit levels are checked to confirm adequate oxygen-carrying capacity.

BUN and/or creatinine levels are useful in critically ill neonates presenting with obstructed pulmonary venous return.

Imaging Studies

Chest radiography

In partial anomalous pulmonary venous connection (PAPVC), lung fields often demonstrate increased pulmonary vascular markings. In addition, an enlarged right-heart border from the volume loaded right heart is seen. In patients with scimitar syndrome, a diagnostic vertically-directed crescent shadow is observed to the right of the mediastinal silhouette.

In TAPVC, obstruction to pulmonary venous drainage determines the appearance of the lung fields on chest radiography. In patients without obstruction, the pulmonary vascular bed is plethoric and pulmonary artery is prominent. In patients with obstruction, severe pulmonary edema is the commonest finding. A prominence of the pulmonary artery shadow and the right atrial (RA) silhouette are often observed. In supracardiac drainage, the prominence of the upper mediastinum can create the classic snowman or figure-8 appearance.

Echocardiography

In PAPVC, echocardiography is typically used to help delineate the anatomy of the pulmonary venous drainage and the atrial septum. Confirmation of the normal drainage of the remaining pulmonary veins is an important part of the echocardiographic examination.[14, 15]

In TAPVC, with 2-dimensional echocardiography and color-flow Doppler mapping, the anomalous venous anatomy is usually well defined. Diagnostic findings include distension of the right ventricle, the presence of a vascular confluence coupled with absent venous drainage to the left atrium on the Doppler interrogation, the presence of an accessory common vein, a dilated coronary sinus and turbulent flow in the right atrium with a right-to-left shunt. Demonstration of turbulence or flow acceleration in the pulmonary veins is also used to diagnose obstruction in the pulmonary venous circuit. In addition, right-heart pressures and other cardiac anomalies can be determined. Echocardiography has shown excellent sensitivity and specificity in fetal diagnosis[15] and as a prognostic tool and has supplanted angiography in the vast majority of cases.[16]

CT and MRI

In nonurgent cases of PAPVC or TAPVC, CT or MRI may be used to further delineate the cardiac anatomy. The ability to form 3-dimensional reconstructions with these imaging modalities is evolving rapidly.

In particular, contrast-enhanced magnetic resonance angiography (MRA) provides complete anatomical and functional assessment of the pulmonary circulation. When compared to echocardiography, MRIA has been shown to offer a better visualization of the whole length of the pulmonary veins, the communicating veins, and the accessory pathways. Additional benefits include the possibility of qualitatively and quantitatively evaluating the amount of anomalous pulmonary blood flow, the Qp:Qs (using phase-contrast MRI). The secondary effects of the shunt on pulmonary arteries as well as cardiac chambers are also detectable in the same study.[17, 18]

Diagnostic Procedures

Cardiac catheterization is used infrequently for diagnosis in routine TAPVC or PAPVC because of the refinements in echocardiography. Cardiac catheterization is helpful in patients in whom echocardiographic findings are ambiguous or in patients with other complex defects. As a result of the mixing of oxygenated pulmonary venous effluent and deoxygenated systemic venous blood (oxygen saturations) are almost identical in all chambers of the heart in patients with TAPVC.

The site of the anomalous connection is located precisely with angiography by locating the step-up in saturations along the systemic venous pathway. Catheterization is also helpful in defining the anatomy of pulmonary-vein stenosis, which may develop after TAPVC is repaired.

In older patients with PAPVC, cardiac catheterization may be required to exclude coronary artery disease, to assess right-heart pressures, to ascertain the reversibility of any pulmonary arterial hypertension, and to calculate the shunt fraction.

Balloon atrial septostomy (BAS) may assist in evaluating the hemodynamic status of patient by unmasking previously undetected severe venous obstruction. The persistence of pulmonary hypertension following BAS should raise the suspicion of an obstruction to the venous drainage in an extracardiac location.

Histologic Findings

TAPVC is associated with hypertrophy of the media of the pulmonary veins and arteries. This finding is most prominent in patients with evidence of pulmonary venous obstruction, and it is most important in the extrapulmonary and intrapulmonary veins. Intimal proliferation and fibrous thickening of the pulmonary veins, with lymphangiectasia, is a common microscopic finding in patients with TAPVC.

In patients with recurrent stenosis a diffuse fibrous proliferation of the intima is often seen, usually at the site of the surgical anastomosis, although these changes can be seen along the whole length of the vein. Occasionally, those nonspecific changes can involve the intraparenchymal portions of the venous bed, mimicking the pathological changes of the veno-occlusive disease.

 

Treatment

Medical Therapy

Obstructed total anomalous pulmonary venous connection (TAPVC) presents immediately after birth with severe cyanosis and poor systemic perfusion and constitutes a medical and surgical emergency.[19, 20] The anatomic lesions limit the extent of hemodynamic and metabolic resuscitation obtainable with conventional noninvasive treatment. These are intended to stabilize the patient's conditions and provide the best possible preoperative status prior to surgical repair, which still represents the criterion standard of care for this otherwise fatal condition.

Sedation, ventilation, or hyperventilation with 100% oxygen and maintenance of pCO2 levels below 30 mm Hg contribute to improve effective pulmonary blood flow. Administration of prostaglandin E1 (eg, alprostadil, PGE1) may allow some right-to-left shunting at the level of the ductus arteriosus. This may increase systemic cardiac output, although it may do so at the expense of pulmonary blood flow. Aggressive correction of systemic acidosis with sodium bicarbonate is mandatory, as well as optimization of hematocrit to improve oxygen-delivery capacity.

In neonates or infants with unobstructed TAPVC, medical therapy is directed at compensating right ventricular failure, hypoxia, and congestive heart failure. In these cases, mild inotropic support, diuresis, and low levels of inspired oxygen are often used. Assisted ventilation is rarely needed. In selected cases, α-blockade can be used to reduce the incidence of pulmonary hypertension.

Partial anomalous pulmonary venous connection (PAPVC) is most commonly diagnosed as a result of an incidental finding of murmur or abnormal chest radiographs during routine medical examination. Those who present with primary arrhythmia or right heart failure may benefit from antiarrhythmic agents or management of right heart failure while the diagnostic workup is being completed and before surgical correction is considered.

Surgical Therapy

Balloon atrial septostomy (BAS) has been used with some success to decompress the venous circuit and improve cardiac output in cases of a restrictive interatrial communication.

More recently, stenting of obstructed vein has emerged as a valid aid to provide immediate relief of pulmonary hypertension and cardiogenic shock allowing a more effective hemodynamic stabilization prior to surgical intervention.[21, 22, 23, 24, 25]

Similarly some centers have advocated the use of extracorporeal membrane oxygenation (ECMO) during resuscitation. In few cases, ECMO has been adopted after the repair to support neonates with residual pulmonary hypertension.[26, 27]

Several techniques have been proposed for the surgical repair of both PAPVC and TAPVC. Whereas the first is normally corrected without complications, TAPVC still carries significant morbidity and mortality in low volume centers, due to the severe hemodynamic and metabolic compromise at presentation. Moreover, 10-15% of patients undergoing repair of TAPVC require multiple interventions due to recurrent stenosis after initial successful correction, with an increasingly poor outcome at each representation.[19, 28]

Most recently, a technique aimed at eliminating any suturing to the vein wall, called sutureless technique, was proposed to relieve postrepair stenosis and avoid recurrence. At present, indications for using this technique are being extended to the correction of primary venous anomalies.[29]

The goal of surgical repair is to recreate an unobstructed venous inflow to the left side chambers and repair of the associated anomalies, such as closure of atrial septal defect (ASD).

Preoperative Details

Preoperative echocardiographic definition of the pulmonary venous anatomy and associated defects is important in planning the appropriate cannulation technique and surgical approach. This point is especially pertinent in PAPVC, in which the location of the anomalous pulmonary venous drainage influences the use of a minimally invasive sternotomy incision and placement of venous cannulae. A high insertion of the anomalous vein in the superior vena cava (SVC) makes a minimally invasive approach considerably more difficult.

In patients with obstruction resulting in cyanosis and acidosis, resuscitative correction should be attempted while emergency surgical correction is being organized.

Intraoperative Details

Total anomalous pulmonary venous connection

Aorto-bicaval cannulation offers flexibility to repair all forms of TAPVC. Cardiopulmonary bypass is instituted and the patient is cooled to mild-to-moderate hypothermia. The ductus arteriosus is ligated at this point. The aorta is cross-clamped, and cold antegrade cardioplegia is administered.

Many surgical techniques have been proposed to correct different types of TAPVC, but none has really succeeded in avoiding in as many as 15% of the cases relentless pulmonary vein stenosis, often recurrent, which complicates the recovery of these children.

A novel technique, introduced a decade ago, named the sutureless technique seems to offer some benefit from this troublesome complication. Initially introduced to treat the subsiding restenosis in children who already underwent primary repair with the traditional anastomotic techniques, it has been adopted and developed in the author's center as the preferred primary repair for most cases of TAPVC, congenital pulmonary vein stenosis, and complex cases of mixed types with encouraging results.

In supracardiac TAPVC, the vertical vein is usually ligated next to its connection to the systemic vein.[30, 31] The exposure of the vein confluence can vary. The pulmonary venous confluence can be seen in the posterior pericardium by retracting the heart rightward and anteriorly or by a superior access between the ascending aorta and SVC.[32] Alternatively, it can be accessed in the right pericardial fossa by a vertical incision through the right atrium, the interatrial septum, and the left atrium (LA). Generally, an incision is created in the pulmonary venous confluence to match a corresponding incision in the posterior wall of LA and extending into the LA appendage.

With care to avoid distortion, a pulmonary confluence–to-LA anastomosis is created using fine sutures in order to minimize the degree of intimal hyperplasia and potential restenosis. The use of absorbable suture material (polydioxanone [PDS]) versus nonabsorbable suture material (eg, Prolene) and running versus interrupted stitches are controversial. However, neither of these techniques has demonstrated a clear advantage over the others. The primary goal is a large, unobstructed anastomosis. Although deep hypothermic arrest is only seldom necessary,[28] a short period of low-flow cardiopulmonary bypass may be desirable for a meticulous anastomosis.

Repair of cardiac TAPVC involves unroofing the coronary sinus through an incision between the coronary sinus and the fossa ovalis, thus creating a large ASD. The pulmonary vein ostia are visualized through the coronary sinus and its connection with the confluence. Then, a patch is used to reconstruct the atrial septum, leaving the pulmonary venous drainage to flow through the unroofed coronary sinus into the LA. When the anomalous veins drains directly into the right atrium (RA), the interatrial septum is detached posteriorly and reattached to the right of the right side pulmonary vein ostia.[33]

For infracardiac TAPVC, the technique is similar to that described for supracardiac TAPVC. The pulmonary venous confluence tends to be oriented vertically, typically in a Y -shape and is extrapericardial. As a consequence, the incision into the LA is relatively vertical or Y- shaped. Some surgeons do not ligate the vertical vein to provide access to a low pressure system in cases of a particularly small and restrictive LA. Others ligate the connecting vein immediately above the diaphragm and use the intrapericardial portion of this vein to produce a larger anastomosis.[34]

Surgical correction of mixed TAPVC depends on the exact anatomy and site of pulmonary venous connections. A combination of the aforementioned procedures is usually required to completely redirect pulmonary venous blood to the LA.[35, 36] A possible alternative is represented by the use of a sutureless technique to treat the complex patterns of connections in this subgroup, during which the atrium is anastomosed to the posterior pericardium to cover all veins emerging in the area.[37]

When a sutureless technique is used, the pulmonary vein confluence is incised through the posterior pericardium, and the LA is opened through a long incision extending from the atrioventricular groove to the appendage. This is then sutured onto the pericardium surrounding the venous confluence. Pulmonary blood then flows from the vein directly into the atrial cavity, and hemostasis is secured by the fibrous continuity between the pericardium and the pulmonary veins.

Careful visualization of the phrenic nerve is mandatory in this technique because the suture line is often juxtaposed to its course on the left side. The resulting anastomosis requires no suture placement into the pulmonary vein, minimizing direct surgical trauma and intimal fibrosis and hyperplasia secondary to suturing.[19] Moreover, the incision of the pulmonary veins can be extended into the hilar portion and even into the distal portion of their intraparenchymal tract due to the continuity offered by the layers of the mediastinal pleura and areolar tissues around the veins, thus creating a lung-to-atrium continuum to the blood flow.

Partial anomalous pulmonary venous connection

The position of the anomalous pulmonary vein determines the site of cannulation in the SVC. In most patients, the SVC or the innominate vein is cannulated to provide venous drainage for the upper extremities. After cardioplegic arrest, systemic normothermia is maintained. The RA is opened, and the pulmonary veins and any ASDs are identified.

A double-patch technique with glutaraldehyde-treated autologous pericardium is typically used to create a baffle which redirects pulmonary venous blood from the anomalous right upper pulmonary vein beneath the baffle through the ASD into the LA. The second patch is used to augment the SVC on top of the baffle to prevent obstruction to RA inflow.[5]

A single-patch technique has been proposed. This involves a transverse atriotomy extending along the lateral aspect of the RA and across the cavoatrial junction along the SVC to just proximal to the point of inflow of an anomalous right superior pulmonary vein. A single pericardial patch is then fashioned to close the sinus venosus type of ASD and to create a baffle through the posterior SVC and over the origin of the right superior pulmonary vein. The atriotomy is then closed by incorporating the lateral limit into the suture line.

As an alternative, a new SVC-RA junction (Warden operation) is established by dividing the SVC just distal to the anomalous pulmonary venous entry and translocating the cephalic end of the SVC to a site at the RA appendage, where a SVC-to-RA anastomosis is performed. Take care to resect the trabeculations in the appendage to prevent obstruction of systemic venous drainage. The divided cardiac end of the SVC (bearing the anomalous pulmonary venous connection) is closed, and in the RA, a baffle is created from the site of the anomalous pulmonary vein to the ASD and LA.

A study by Pace Napoleone et al of 59 patients who underwent intracardiac patch rerouting for PAPVC, including 14 who also had SVC patch enlargement, found good medium-term postoperative results. At mean follow-up of 46 months, the investigators found the rate of arrhythmias (including sinus node dysfunction) to be comparable to that associated with other surgical techniques. In addition, all patients were asymptomatic, and 55 of them (93%) presented with sinus rhythm and were antiarrhythmic drug-free.[38]

Postoperative Details

Poor hemodynamic performance following repair of PAPVC or TAPVC should raise concern of potential obstruction at the site of repair. In those cases, chest radiography often reveals pulmonary edema, although this finding is nonspecific because it seen in many patients with preoperative pulmonary venous obstruction despite normal hemodynamics. Any suspicion of residual postoperative pulmonary venous obstruction should prompt echocardiography to interrogate the pulmonary venous anastomosis.[39] When possible MRA is indicated to refine diagnosis.

Patients with obstructed TAPVC often have a difficult postoperative course secondary to high pulmonary vascular resistance and poor lung compliance. Some centers advocate the routine use of ECMO after surgical correction in these patients.

Follow-up

Pulmonary venous obstruction may arise in as many as 15% of patients after repair of TAPVC.

Most patients represented by obstruction at the site of anastomosis, presumably as a result of postoperative scar formation or distortion of the veno-atrial junction. Repeat surgery in these cases produces generally favorable results. However, in a smaller number of patients, a diffuse stenotic process involving the whole length of the pulmonary veins including their intrapulmonary course occurs. This process may progress to almost complete vein occlusion. When the lesion is bilateral, prognosis is poor. Sutureless techniques and/or lung transplantation may improve the outlook in this difficult subgroup.

Patients with PAPVC should also be followed up for evidence of stenosis at the site of pulmonary venous repair, although the diffuse stenosis described after repair of TAPVC is rare. See the image below.

Follow-up CT scan performed after repair of total Follow-up CT scan performed after repair of total anomalous pulmonary venous connection (TAPVC). The right upper pulmonary vein (RUPV) appears severely stenosed (red arrow).

Complications

Residual obstruction at the site of pulmonary venous repair is manifested by poor cardiac output and chest radiographic findings of pulmonary congestion. The principle diagnostic feature is turbulence at the pulmonary venous anastomotic site, as noted on echocardiography. Residual turbulence may create a cycle of local injury, hyperplasia, and increasing turbulence, perpetuating a process of diffuse pulmonary vein stenosis. Pulmonary vein stenosis may remain localized to the site of anastomosis, may progress unilaterally with diffuse pulmonary vein stenosis or may progress with bilateral diffuse pulmonary vein stenosis.

Outcome and Prognosis

TAPVC is associated with hospital mortality ranging from 2% to 20%. Risk factors include poor preoperative status (eg, acidosis), obstruction, high pulmonary vascular resistance, young age, small left ventricle, and single-ventricle anatomy[40, 41, 42, 43, 44, 45, 46]

Long-term prognosis after successful repair of TAPVC is favorable. Approximately 10-15% of patients have evidence of late pulmonary-vein obstruction. For this reason, long-term surveillance is important. Postoperative stenosis can be recurrent and progressive.[47, 48] Among patients with postrepair pulmonary vein stenosis, sutureless repairs are associated with superior freedom from recurrent stenosis.[49]

Long-term prognosis for patients after repair of PAPVC is excellent in the absence of irreversible pulmonary hypertension. In children, closure of an associated atrial septal defect (ASD) almost eliminates the risk of the late development of atrial arrhythmias. In the older population the presence of preoperative arrhythmias represent a risk factor for persistent arrhythmias and mortality after the repair.[50, 51] In a recent series published by the Mayo Clinic, 68% of patients operated at adult age represented reduced right ventricular size at short-term control; however, only 10% had a significant improvement in systolic function and nearly 15% had a marked decrease.[52] In a recent series of 30 patients operated on with the Warden procedure, residual systemic vein pathway obstruction was observed in 10% of the younger patients, requiring reoperation. Sinus node function was preserved in all cases.[53]

A recent study of the European Congenital Heart Surgeons Association (ECHSA) has demonstrated good long-term outcomes following repair of scimitar syndrome using 2 established techniques: intraatrial baffle (56% of patients) and reimplantation of the scimitar vein to the left atrium (31%). Total late mortality was 3%, and freedom from vein stenosis was 84% and 86%, respectively.[54]

Future and Controversies

Improved neonatal care and surgical techniques have greatly improved, reducing perioperative mortality to below 10% in most centers. However, in particular subsets of patients, the risk of surgical death is still extremely high. In particular, neonates with single ventricle circulations and obstructed total anomalous pulmonary venous connection (TAPVC) requiring emergency repair have a high rate of surgical mortality despite optimal medical management and prompt surgical repair.

A second frontier in the treatment of TAPVC is represented by postsurgical vein obstruction. Improved understanding of the vascular biology responsible for diffuse pulmonary vein stenosis in this group is required. At present, the wide adoption of a sutureless technique for postrepair stenosis as well as primary repair seems to offer the most promising result and long term patency.[51, 55, 56, 57, 58, 59]