Abstract
Background
Total anomalous pulmonary venous connection (TAPVC) is a rare cyanotic abnormality that accounts for about 1%–3% of congenital heart disease malformations. TAPVC is a condition in which there is no direct connection between all four pulmonary veins and the left atrium but makes abnormal connections to the right atrium or systemic venous system. TAPVC caused a high mortality rate of 80% in the first year of life, and 50% of them die within 3 months after birth without intervention.
Objectives
The aim of this review is to elucidate the various treatment considerations of TAPVC.
Methods
A literature search was conducted on PubMed, ScienceDirect and Google Scholar using various combinations of keywords related to treatment of TAPVC. The citations from all selected articles were reviewed for additional studies.
Results and Conclusion
TAPVC intervention, including medical and surgical, is tailored to each type of TAPVC. Catheter-based interventions are frequently used to temporize neonates and provide time to optimize patients medically prior to definite repair. Corrective surgery is required for all patients with this condition. Several latest catheter-based or surgical intervention technique modifications have also been reported.
Keywords
Introduction
Total anomalous pulmonary venous connection (TAPVC), also referred to as total anomalous pulmonary venous return/drainage (TAPVR/TAPVD), is a rare but heterogeneous anomaly, accounting for 1% to 3% of cases of congenital heart disease.1,2 This anomaly is characterized by the failure of confluent pulmonary veins (PV) to be absorbed into the dorsal part of the left atrium (LA) and in combination with a persistent connection to the systemic venous system. Historically, TAPVC caused a high mortality rate of 80% in the first year of life, and 50% of them die within 3 months after birth without intervention. 3 Advances in surgical technique, increased diagnostic accuracy, and changes in perioperative management have contributed to the reduction in perioperative mortality, although several factors such as surgical repair of the neonate, preoperative pulmonary venous obstruction (PVO), mixed anatomic variations, single ventricular physiology, and heterotaxy remain important risk factors for poor postoperative survival.1,4 In this literature review, we narratively review the current therapeutic considerations, including postoperative follow-up of TAPVC.
Anatomy and classification
The classification of the most widely used type of TAPVC is based on the location of the PV fusion, which was first introduced by Darling et al. in 1957. TAPVC is divided into four types: (1) Supracardiac, (2) Cardiac, (3) Infracardiac, and (4) Mixed type TAPVC (Figure 1).5–7 (1) Supracardiac TAPVC (type 1)
TAPVC anatomical classification. (a) Supracardiac TAPVC. RPV and LPV form a horizontal pulmonary venous confluence that connects to the LIV through a vertical vein; (b) Cardiac TAPVC. pulmonary venous confluence connects to CS; (c) Infracardiac TAPVC. Pulmonary veins form a vertical confluence that descends below the diaphragm and joins the portal vein; (d) Mixed type TAPVC. In this example, LPV connect to LIV, and RPV to CS. CS: coronary sinus; HV: hepatic veins; LIV: left innominate vein; LPV: left pulmonary veins; PV: portal vein; RPV: right pulmonary veins; SV: splenic vein; SMV: superior mesenteric vein. (from: John Wiley and Sons, Echocardiography in Pediatric and Congenital Heart Disease: From Fetus to Adult, 3rd Edition by Lai et al., 2021).
The prevalence of supracardiac TAPVC is 45%–55%. This type of TAPVC occurs when the common pulmonary venous drainage leads to a superior part of the heart, namely the innominate vein, superior vena cava (SVC), or azygous vein via the vertical vein. Although obstruction is not frequent, obstruction can also occur due to compression of the vertical vein by the left main bronchus and left pulmonary artery (PA) or narrowing of the vertical venous base towards the innominate vein.6,8 (2) Cardiac TAPVC (type 2)
Cardiac TAPVC occurs in approximately 20%–30% of cases. Pulmonary venous drainage into the coronary sinus or, in some cases, directly to the right atrium (RA); therefore, the coronary sinus is often dilated. Cardiac obstruction is not usually found; however, it can occur in the common PV or ostium of the coronary sinus or PVs.7–9 (3) Infracardiac TAPVC (type 3)
Infracardiac TAPVC occurs in approximately 25% of cases. Pulmonary venous drainage goes to the descending vertical vein anterior to the esophagus through the diaphragm (esophageal hiatus) to the portal vein or ductus venosus.6,7 This picture of pulmonary venous drainage is often called the “inverted Christmas tree”, where the PVs exit the pulmonary hilus in an oblique direction like tree branches. This type is often accompanied by obstruction at the level of the diaphragm or ductus venosus. Therefore, patients with this type are susceptible to hypoxemia and pulmonary hypertension (PH) pre and postoperatively.8,9 (4) Mixed type TAPVC (type 4)
Mixed type TAPVC occurs in approximately 5% of cases. Abnormalities of this type may include a combination of components from the previous type. The right lung and left lung have different venous drainage from one another.8,9 The mixed variant is often associated with other major structural heart defects and can have obstructions at multiple levels. The most common mixed connections are the left PV connection to the vertical vein leading to the left innominate vein and the right PV connection to the RA or coronary sinus. 7
Management
Medicals
Intensive diuretics should be given to prevent pulmonary volume overload conditions, especially in TAPVC without PVO. Infants with severe pulmonary edema (due to infracardiac type or other types with obstruction) should be intubated, sedated, or even paralyzed if necessary before emergency surgery. Metabolic acidosis, a fairly frequent complication, must be corrected immediately. In cases of TAPVC with PH, as in the infracardiac type, prostaglandins (PGE1) can also be given to keep the ductus open and maintain adequate systemic flow. However, a large patent ductus can also increase the degree of cyanosis.6,10
Obstructive TAPVC may present with PH originating from the PVs (post-capillary). Administration of inhaled nitric oxide (iNO) in this condition is not recommended. 11 Sudden pulmonary vasodilation with potent pulmonary vasodilators tends to be ineffective, non-physiologic, and may cause sudden and severe worsening.11,12 However, iNO has a vital role in postoperative care because PH can persist even if the obstruction is resolved postoperatively.13–15Significant reductions in pulmonary vascular resistance (PVR) and PA pressure can be seen when iNO is administered postoperatively. 16
Catheter-based interventions
Catheter-based interventions are frequently used to temporize neonates and provide time to optimize patients medically prior to definite repair. 17 Balloon or blade atrial septostomy (BAS) is performed if the interatrial defect is small (restrictive), while surgery cannot be performed immediately. However, this procedure is not very useful if the venous anomaly is obstructed.6,10
Percutaneous PV stent placement in vertical vein obstruction in supracardiac and infracardiac TAPVC were most commonly reported (Figure 2).18–22 Repeated angioplasty for in-stent restenosis has also been reported.
23
Case report of stent placement between the pulmonary confluence and the LA as a bridge to surgery has also been described.
24
Chamberlain et al. reported successful palliation in premature and low birth weight infants by serial catheter-based interventions as a viable management option to allow them to achieve an acceptable weight and maturity for surgical repair.
25
Sometimes, the vertical vein was deliberately not operated on in order to prevent a PH crisis, with embolization with a coil or plug to be performed if the right heart volume load increased.26–28 Percutaneous intervention using coronary stent via a guiding catheter demonstrating successful dilation of the obstructed vertical vein in supracardiac TAPVC. (from: John Wiley and Sons, Catheterization and Cardiovascular Interventions, Stenting of the vertical vein in obstructed total anomalous pulmonary venous return as rescue procedure in a neonate, Lo-A-Njoe et al., 2006; 67(5): 668-670, https://doi.org/10.1002/ccd.20715).
Extracorporeal membrane oxygenation (ECMO) is another intervention used to temporize neonates until the diagnosis is confirmed or when medical management is unable to correct severe hypoxemia, acidosis, and hemodynamic instability; and interventions or surgical repair are arranged.22,29,30 ECMO has allowed surgical correction even in the most severely ill patients. Postoperatively, ECMO can also be useful for those with residual PH or aid in cardiac recovery. 17
Surgical
Indication and Timing
Corrective surgery is required for all patients with this condition. There is no palliative procedure. All infants with PV obstruction should be operated on as soon as possible after diagnosis. Infants who do not have PVO but have uncontrolled heart failure are usually operated on when stable on a semi-elective basis. TAPVC without obstruction or severe heart failure can be corrected at neonates or delayed until 3–6 months of age.6,17
Procedure and technique
Although procedures vary with the location of the anomalous drainage, all procedures are intended to redirect the PVs to the LA (Figure 3). The principle of surgery is to provide a connection from PV to the LA, interrupt the connection with the systemic venous system, close the interatrial defect, and other specific actions depending on the type of TAPVC anomaly.6,8,17 The surgical technique varies from surgeon to surgeon; some use the RA approach to reach the LA, and others directly reach the LA posterior wall. Several support the use of deep hypothermic circulatory arrest (18°-20°C).
6
Recently, a sutureless technique has been increasingly used to prevent postoperative PV stenosis/obstruction (Figure 4).17,31 A meta-analysis by Wu et al. demonstrated that a lower occurrence rate of postoperative PVO and reoperation due to PVO were associated with sutureless techniques than conventional surgery. Meanwhile, hospitalization time and postoperative mortality were not statistically different between the two surgical approaches.
32
Surgical approaches to various types of TAPVC. (a) Supracardiac type; (b) Cardiac type to right atrium; (c) Cardiac type to coronary sinus; (d) Infracardiac type. (from: Elsevier Science & Technology Journals, Park's Pediatric Cardiology for Practitioners, 7th Edition by Park and Salamat, 2021). Surgical repair for TAPVC. Conventional repair (pulmonary vein insert with potential suture line stenosis) and sutureless repair (pulmonary vein insert) techniques are shown. (from: Elsevier, The Journal of Thoracic and Cardiovascular Surgery, Primary sutureless repair for “simple” total anomalous pulmonary venous connection: Midterm results in a single institution, Yanagawa et al., 2011; 141(6): 1346-1354, https://doi.org/10.1016/j.jtcvs.2010.10.056).
In supracardiac type, a side-to-side anastomosis is performed between the common pulmonary venous sinus and the LA. Vertical vein ligation and ASD closure were performed using a cloth patch (Figure 3(A)).6,17
Repair of cardiac type TAPVC to the RA involves excision of the atrial septum, where the PV opening is then closed using a patch. In addition, the PVs drain all the way to the LA (Figure 3(B)). ASD may have to be enlarged. While in cardiac type TAPVC to the coronary sinus, an incision is made in the anterior wall of the coronary sinus (unroofing) to make a connection between the coronary sinus and the LA. Subsequently, the ASD and coronary sinus ostium were closed using a single patch (Figure 3(C)). This procedure results in drainage of coronary sinus blood with low oxygen saturation into LA.6,17,33
In infracardiac type, a large vertical anastomose was performed between the common pulmonary venous sinus and the LA. Afterward, the common PV leading to the abdominal cavity was ligated at a level above the diaphragm (Figure 3(D)).6,17
At the time of TAPVC repair, the surgeon must decide whether the vertical vein should be ligated. The unligated vertical vein can act as an import-decompression conduit for the non-compliance small LV and can help minimize the consequences of a postoperative PH crisis. An unligated vertical vein can lead to a significant left-right shunt, although in most cases, the hemodynamic consequences may be minor,34,35 and most will close spontaneously on their own. 17
A novel surgical technique was successfully described by Mehta et al. in a rarely combined supracardiac and infracardiac drainage of TAPVC (mixed type) without a common pulmonary venous chamber, in which a common pulmonary venous chamber was created, and anastomosis of this chamber to the LA was combined with interruption of both the ascending and descending anomalous connections. 36 Another palliative technique in low birth weight newborns suffering from critical obstructive supracardiac TAPVC by establishing anastomosis without cardiopulmonary bypass (CPB) between pulmonary venous confluence and LA appendage (Sarmast – Takriti Shunt) was successfully reported. 37
Postoperative mortality
The surgery mortality rate is between 5% and 10% for infants without PVO and will be higher by 20% in the infracardiac type with obstruction. The most common causes of postoperative mortality are PH and PV stenosis due to its closure. Seale et al. reported a 3-year survival of 85%, with independent risk factors for death consisting of early age at surgery, hypoplastic/stenotic PVs, complex cardiac lesions, postoperative PH, and postoperative PVO. Mortality from PV stenosis alone reached 40%, where the risk factors for postoperative PV stenosis include the degree of preoperative morphological abnormalities and the absence of common confluence in the PV structure.6,10,38,39 Xiang et al. reported that the survival rates of repaired mixed type at 3 and 5 years were 90.9% ± 8.7%. 40 The anatomical type of TAPVC is less correlated with surgical outcome, but supracardiac TAPVC has a better outcome than other types.1,41
Surgical complications
Several surgical complications include paroxysmal PH, which is associated with a small left heart and poor compliance, with consequent heart failure and pulmonary edema, which may require prolonged postoperative respiratory support. 6 Postoperative arrhythmias are usually atrial arrhythmias, including sick sinus syndrome/sinus node dysfunction.42,43 Obstruction at the anastomotic site or PV stenosis is rare, ranging from 10%–15%.1,6,38,44 Reoperation is required in approximately 10 to 15% of patients with isolated TAPVC with individual PV stenosis, or surgical anastomosis is the main reason for reoperation.13,38,45–47 In addition, neurodevelopmental delay and growth retardation may also occur post-surgery. 48
Post-surgery follow-up
Evaluation at 1 month and every 6 to 12 months are recommended for long-term (late) surgical complications such as PVO and atrial arrhythmias. PVO at the site of the anastomosis or the appearance of delayed PV stenosis may occur in about 10% of patients and require reoperation. These complications are usually seen within 6 to 12 months after improvement.17,38 The possibility of PV stenosis requires cardiac catheterization and angiocardiography. Follow-up was continued for 5 years if there were no residual defects and PH. 49 Some patients may have atrial arrhythmias, including sick sinus syndrome, which require medical treatment or pacemaker therapy. Periodic arrhythmia screening is not routinely recommended in asymptomatic children with repaired TAPVC. Periodic Holter may be considered in asymptomatic adolescents. Activity restriction is usually not necessary unless PV obstruction or PH develops. Prophylactic measures of infective endocarditis should be considered in the first 6 months after surgery, after which it is no longer necessary. Children with TAPVC should undergo appropriate surveillance, screening, and/or referral for neurodevelopmental disorders.6,49,50
Conclusion
TAPVC is a rare and severe cyanotic congenital heart disease with a prevalence of 1%–3% of all congenital heart diseases. The universal TAPVC classification is divided into supracardiac, cardiac, intracardiac, and mixed type TAPVC. TAPVC management in medical, catheter-based, and surgical procedures should be tailored for each type of TAPVC, taking into account the patient's clinical condition, including the current intervention procedure.
Footnotes
Author contributions
EPBM contributed to conceptualization, validation, investigation, writing and preparation of the original draft, and visualization. MAR contributed to conceptualization, validation, resources, writing, reviewing, and editing of the manuscript, visualization, and supervision.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
