In individuals with pulmonary atresia with intact ventricular septum

Due to anatomic heterogeneity, patients with pulmonary atresia and intact ventricular septum undergo a variety of individualised approaches. The best patients are candidates for either biventricular surgical repair or repair by means of laser perforation of the imperforate valve and interventional balloon dilation. ^{Reference Anderson, Anderson and Zuberbuchler2–Reference Anderson and Ho4,Reference Daubeney, Delany and Anderson15,E54–E57} At the other end of the spectrum, patients are found with muscular overgrowth of the apical ventricular component and a hypoplastic ventricular inlet. In this category, most are candidates only for conversion to the Fontan circulation.^E112

Following preliminary systemic-to-pulmonary arterial shunting and pulmonary valvotomy, multi-institutional studies have demonstrated that approximately one-tenth of these patients remain in a “grey area”. Because it is well accepted that the right ventricle in this malformation is intrinsically tripartite, and only become bipartite or unipartite from muscular overgrowth and cavitary obliteration, investigators have attempted right ventricular overhaul in selected cases as an intermediate step towards either the biventricular or a one-and-a-half ventricular repair. Data provided by the Congenital Heart Surgeons Society, and the group working in Melbourne, indicate that creation of the superior cavopulmonary connection is an effective alternative to attempting “right ventricular overhaul” as a step towards biventricular repair. ^{Reference Anderson, Anderson and Zuberbuchler2–Reference Anderson and Ho4,Reference Hanley, Sade and Blackstone6,Reference Hoashi, Kitano and Kagisaki8,E15,E54–E57}

In the setting of straddling and overriding tricuspid valves

Depending on the degree of overriding of the atrioventricular junction, the morphologically right ventricle will be more or less incomplete. With minimal override in this setting, there has been a renaissance of interest in biventricular repair. ^{Reference Anderson and Ho3–Reference Barron7,Reference Hanley9,E31,E35,E36} Between the extremes of complete biventricular repair and conversion to Fontan circulation, some individuals benefit from creation of the superior cavopulmonary connection.

Transposition with ventricular septal defect and hypoplastic right ventricle

This subset of patients (Fig. 1) may be treated initially by balloon atrial septostomy and banding of the pulmonary trunk. Creation of the superior cavopulmonary connection can then be performed as an adjunct to the arterial switch, with subsequent closure of the ventricular septal defect, when the pulmonary vasculature has adequately matured. ^{Reference Chowdhury, George and Sankhyan12,Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E27–E30}

Figure 1.

Volume rendered images (a–c), oblique coronal images (d and e), and oblique axial image (f) show a small right ventricle (RV) in the setting of transposition. Note is made of pulmonary valvar (PV) stenosis and a subaortic ventricular septal defect (*). [A = aorta; LV = left ventricle; P = pulmonary trunk; LA = left atrium].

Transposition with ventricular septal defect and hypoplastic left ventricle

The cavopulmonary anastomosis is part of the treatment of early atrial septostomy followed by delayed atrial switching. ^{Reference Chowdhury, Airan and Talwar20,E2,E6,E24,E27,E28} This is one of the rare instances where it is the morphologically left ventricle that is unloaded so as to support only half of the pulmonary circulation.

Congenitally corrected transposition with or without a ventricular septal defect and pulmonary stenosis or pulmonary atresia

Many such individuals have morphologically right ventricles of borderline size. In this setting, the cavopulmonary connection has been performed as an adjunct to the “double-switch” procedure, or to delay the Rastelli procedure in which the pulmonary ventricle would be made anatomically and functionally smaller by the intracardiac baffle and ventriculotomy. ^{Reference Malhotra, Patel and Pandya13,Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E2,E5,E6,E13,E18,E19,E37,E38,E58}

Double outlet right ventricle with remote interventricular communication

In a small subset of patients with double outlet right ventricle, the defect is remote from either outlet.^{E29,E35,E39,E59,E82} In order to avoid compromising a portion of right ventricular volume by placement of a large intraventricular tunnel, some have been treated by creation of the cavopulmonary connection. An analogous situation may be seen in patients with transposition and a ventricular septal defect remote from the outlet, in whom the classic techniques for repair are untenable. ^{Reference Chowdhury, Airan and Talwar20,E26,E27}

Individuals with supero-inferior ventricles

In many of these patients, the superiorly positioned morphologically right ventricle is grossly hypoplastic. Depending on the type of atrioventricular and ventriculoarterial connections, some patients have been converted to the Fontan circulation, whereas others have been treated with either a biventricular repair or creation of a superior cavopulmonary connection. ^{Reference Anderson, Anderson and Zuberbuchler2–Reference Anderson and Ho4,Reference Van Arsdell18,E25,E38}

Right ventricular hypoplasia

Hypoplasia of the subpulmonary right ventricle is occasionally encountered in those with ventricular or atrioventricular septal defects, tetralogy of Fallot, right ventricular outflow tract obstruction, and transposition with large ventricular septal defects. Although a standard biventricular repair may be possible, many of these individuals have been palliated by creation of a superior cavopulmonary connection (Figs. 2, 3). ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E60–E65}

Figure 2.

The volume-rendered image (a), and the oblique axial image (b) show a hypoplastic tricuspid valve (curved arrow) and a hypoplastic right ventricle (RV). [A = aorta; LV = left ventricle; P = pulmonary trunk; RA = right atrium].

Figure 3.

Volume rendered images (a and b) and oblique axial image (c) shows features of tetralogy of Fallot with hypoplasia of the morphologically right ventricle (RV). Note the patent cavopulmonary shunt. [A = aorta; LV = left ventricle; P = pulmonary trunk; * = subaortic ventricular septal defect; arrowhead = infundibular stenosis].

Individuals with isomeric atrial appendages

A feature of many of these individuals is the presence of bilateral superior caval veins, often with a common atrium and other complex cardiac anomalies (Fig. 4). In these settings, the superior cavopulmonary connection avoids the need to create a complex intra-atrial baffle, thus simplifying the operation. ^{Reference Chowdhury, Airan and Talwar20,E20,E27}

Figure 4.

The axial image (a), the coronal minimum intensity projection image (b), and the oblique axial image (c) show the features of right isomerism, in patient with absence of the spleen, a transverse midline liver, bilateral morphologically right bronchuses, and a right-sided heart with atrioventricular septal defect (star).

Those with Ebstein’s malformation

The indications for creation of a superior cavopulmonary connection in individuals with Ebstein’s malformation are complex and somewhat controversial. Having the right ventricle support only half the pulmonary circulation has generally been used when the ventricle itself is severely dilated, dysplastic, or severely dysfunctional (Fig. 5). ^{Reference Wright, Knight and Thomas14,Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E10,E19,E23,E41,E66,E67} Those with a small or hypoplastic right ventricle are more likely to go down the route of a Starnes procedure and functionally univentricular palliation.

Figure 5.

The volume-rendered images (a and b), the oblique axial image (c), and the oblique coronal image (d) show apical displacement of septal leaflet (yellow arrow) and posterior leaflet (black arrow) of the tricuspid valve in a patient with Ebstein’s malformation. Note the grossly dilated right atrium (RA). [RV = right ventricle].

Univentricular connection to a dominant left ventricle

In this setting, the incomplete right ventricle supports the pulmonary trunk when the ventriculo-arterial connections are concordant, which is usually the case in the setting of tricuspid atresia. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E18,E68} The atriopulmonary variation of the Fontan procedure, although not now performed, produced the closest anatomical situation of a true “one-and-a-half ventricle” arrangement.^{E7,E10,E69,E70} Such patients were on occasion, palliated by creation of the superior cavopulmonary connection (Fig 6).

Figure 6.

The volume rendered images (a, c) and the oblique axial image (b) show absence of communication (dotted yellow arrow) between the right atrium (RA) and the incomplete right ventricle (RV), with fat noted within the right atrioventricular groove. This is classical tricuspid atresia. Note the ventricular septal defect (*) and the hypoplastic and incomplete morphologically right ventricle (RV). The volume rendered image (d, with aorta digitally subtracted) shows the superior cavopulmonary connection, connecting the superior caval vein (SCV) to the right pulmonary artery (RPA). [A = aorta; P = pulmonary trunk; LA = left atrium; LPA = left pulmonary artery].

Special circumstances

In addition to the settings listed above, there are multiple additional circumstances in which the surgeon may opt to construct the superior cavopulmonary connection. ^E1–E172

• Patients with cardiac Ewing’s sarcoma undergoing tumour debulking, patients undergoing resection of a metastatic tumour to the right ventricle along with lobectomy for lung cancer, tricuspid valve endocarditis, and post infarction right ventricle.^E70–E73

• Patients with Uhl’s anomaly and right ventricular endomyocardial fibrosis.^E70–E79

• Patients undergoing the Rastelli procedure with a large intracardiac baffle. ^{E7,E8,E10,E47,E80}

• Atrial redirection with systemic atrioventricular valvular regurgitation.^E25,E80

• Creation of the cavopulmonary connection in the setting of acute postoperative right ventricular dysfunction following an attempted biventricular repair. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E70–E80}

• Conversion from the Fontan circulation in those with pulmonary arteriovenous malformations, Fontan conduit obstruction, recurrent intractable arrhythmias, and protein-losing enteropathy. ^{Reference Chowdhury, George and Sankhyan12,E37,E51,E81}

• As an interstage procedure before biventricular repair to minimise the risk of left ventricular outflow tract obstruction, heart block, iatrogenic atrioventricular valvular regurgitation, and the requirement of a right ventricle-to-pulmonary artery conduit. ^{Reference Hoashi, Kitano and Kagisaki8,E7,E10,E44–E47}

The ability of the subpulmonary ventricle to support the pulmonary circulation subsequent to the creation of the cavopulmonary connection

The safe limits of right ventricular size and function are currently unknown. Different institutions follow different protocols for selection. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E20,E27,E28} A simple means of quantitating the ability of the morphologically right ventricle to handle volume is to measure the size of tricuspid annulus with this measurement then plotted on a nomogram to obtain a z value. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E28,E86–E90} . Intraoperative assessment can be done with direct visualisation and measurement with Hegar’s dilator. Contrast-enhanced and multidetector computed-tomographic angiocardiography in angled oblique views, or cardiac velocity-encoded magnetic resonance imaging, now provide the best comprehensive assessment of ventricular dimensions. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E91–E101} Successful creation of the superior cavopulmonary connection has been achieved when predicted ventricular volumes have been as small as 30%. ^{Reference Wright, Knight and Thomas14,E5,E6,E61} An alternative approach is to combine tricuspid valve Z-scores and pulmonary ventricular volume (Table S1). ^{Reference Chowdhury, Airan and Talwar20,E18,E27} A combination of parameters, therefore, namely, tricuspid Z-values, tricuspid/ mitral valve diameter, right ventricular morphology, right ventricular diastolic volumes, presence or absence of right ventricular-coronary artery fistulae, and the degree of right ventricular endocardial fibroelastosis are usually taken into consideration for the decision-making of construction of a pulsatile superior cavopulmonary connection as opposed to opting for a biventricular or functionally univentricular type of repair.^{E101,E168–E172}

In those with pulmonary atresia and intact interventricular septum, high mortalities ensued when biventricular repair was attempted with tricuspid z-values of less than minus three.^E4 Conversely, good outcomes were achieved with z-values greater than minus three.^E4,E102 Our own criterions are shown in Table S2. We agree with others, nonetheless, that absolute sizes of the right ventricle and the tricuspid valve may not be the only factors for operative success. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E101–E110} Right ventricular compliance, tricuspid regurgitation, relative pulmonary arterial hypoplasia, and pulmonary vascular resistance are important additional considerations in preoperative candidate selection. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20}

Functional analysis can be achieved echocardiographically or angiographically, permitting grading as normal, or mildly, moderately, or severely decreased. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20} Visual inspection of the mural thickness and diastolic filling is also made. ^{Reference Hanley, Sade and Blackstone6,Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E4,E11,E18,E29,E42,E92–E102,E111} Patients with poorly functioning right ventricles are also considered for the superior cavopulmonary connection when there is dilation to 120%. or more and at least a moderate reduction in ventricular function. ^{Reference Hanley, Sade and Blackstone6,Reference Chowdhury, Airan and Sharma19,E4,E11–E14,E18,E29,E42,E92–E102,E111} Recently, velocity-encoded MRI has been used more accurately to quantitate right ventricular systolic and diastolic function and volume. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20,E91-E106}

A third important determinant of the ability of the ventricle properly to function is the pulmonary afterload. In this regard, we took several physiologic criterions into consideration when contemplating creation of a superior cavopulmonary connection, specifically;

• Mean pulmonary arterial pressure less than 15 mm Hg, or less than 20 mm Hg with a net left-to-right shunt.

• Indexed pulmonary vascular resistance less than 3.0 Woods units/m² and a preoperative Mayo index less than 4.0.^E173

• Systemic ventricle end-diastolic pressure less than 12 mm Hg and ejection fraction greater than 0.45.

• Probability of residual pulmonary arterial hypertension, when two-ventricle repair with atrial pop-off was considered a better option. ^{Reference Chowdhury, Airan and Sharma19,Reference Chowdhury, Airan and Talwar20}