Where we are now

With respect to the above-mentioned controversies, the best way to get a snapshot of current practices is to evaluate contemporary data as entered in multi-centre and multi-national databases. The Society of Thoracic Surgeons Congenital Heart Surgery Database is the largest registry of paediatric and congenital heart surgery cases in North America, with over 100 participating centres. In 2010, a review was done of all data in the Society of Thoracic Surgeons Congenital Heart Surgery Database pertaining to surgical operations on patients 0–18 years of age with tetralogy of Fallot with pulmonary stenosis over the 5-year period 2002–2007.Reference Al Habib, Jacobs and Mavroudis² Patients with tetralogy of Fallot with pulmonary atresia, tetralogy of Fallot with absent pulmonary valve, and tetralogy of Fallot with common atrioventricular canal defect were excluded. The data set encompassed ∼3000 operations. Just slightly more than 10% of all operations were some type of palliation, of which the overwhelming majority were systemic-to-pulmonary artery shunts. Among reparative operations, there were 2534 instances of repair of tetralogy of Fallot without a previous cardiac operation, that is, primary repair, and 217 instances of repair of tetralogy of Fallot with a previous cardiac operation. Associations between age and procedure types were assessed. For the neonatal age group (age 0–30 days), initial procedures were about equally divided between tetralogy of Fallot repair and palliation. Across all age groups, the largest number of primary repairs was between 3 and 6 months of age, followed by the 6-month to 1-year category (Fig 1). The largest number of repairs after palliation was in the 6-month to 1-year age category, with 81% of repairs after a previous cardiac operation being performed during the first year of life. Across all age groups, by far the most prevalent surgical approach utilised at the time of primary reparative operations was a ventriculotomy approach with transannular patch reconstruction of the right ventricular outflow tract (Table 1). At the time of primary repair, 52% of patients (1329 of 2534) had ventriculotomy and transannular patch. Only 581 patients (23%) had primary repair with no ventriculotomy (Fig 2).

Figure 1

Primary repair of tetralogy of Fallot in the Society of Thoracic Surgeons Congenital Heart Surgery Database 2002–2007.

Table 1

Tetralogy of Fallot repair without previous surgery: Society of Thoracic Surgeons Congenital Heart Surgery Database 2002–2007.

RV–PA = right ventricle-to-pulmonary artery; TOF = tetralogy of Fallot

The relationship between specific type of repair and age at repair for all instances of TOF repair without previous cardiac surgery. Repair with ventriculotomy and transannular patch is the most prevalent type overall (52% of total), and is most prevalent in every age category. The largest number of instances of primary repair of any type was in the age category of >3–6 months, followed by 6 months to 1 year. Adapted from Al Habib et alReference Al Habib, Jacobs and Mavroudis²

Figure 2

Primary repair of tetralogy of Fallot in the Society of Thoracic Surgeons Congenital Heart Surgery Database 2002–2007.

Repair after prior palliation was performed in 217 cases. Although proponents of an approach based on palliative shunting of symptomatic neonates followed by secondary repair have argued that a potential advantage of this two-staged approach may be interval growth of the pulmonary annulus and reduction of the need for transannular patching, it was nonetheless the case that among patients having reparative surgery after prior palliation, ventriculotomy with transannular patch reconstruction of the right ventricular outflow tract was the most prevalent approach (143 of 217; 66%). Although the focus of the analysis of Society of Thoracic Surgeons Congenital Heart Surgery Database data was on patterns of practice, and although no risk-adjusted analysis of mortality was undertaken, it was reassuring to observe that unadjusted discharge mortality associated with primary repair was just 1.3% (confidence interval: 0.9–1.8%), and was 0.9% (confidence interval: 0.1–3.3%) for repair after previous palliation. Overall discharge mortality associated with initial palliative procedures was 7.5% (confidence interval: 4.7–11.1%). For neonates, discharge mortality was similar among those who underwent palliation and those who had primary repair.

A similar analysis of slightly more recent data was undertaken by members of the European Congenital Heart Surgeons Association, based upon data in the European Association for Cardio-thoracic Surgery Congenital Heart Surgery Database, which is the largest database in Europe dealing with surgical management of congenital cardiac malformations. The data set consisted of all types of reparative operations (n = 6654) on patients with a primary diagnosis of tetralogy of Fallot between 1999 and 2011.Reference Sarris, Comas, Tobota and Maruszewski³ Similarities between North American data and the European Association for Cardio-thoracic Surgery data were striking. Repair via ventriculotomy with transannular patch was the most prevalent technique (n = 3827; 57.5%). Repair via ventriculotomy with non-transannular patch was performed in 1309 patients (19.7%). Repair without ventriculotomy was performed in 1214 patients (18.2%). The investigators explored time-related trends with respect to the various sub-types of repair. Over the past decade, the relative prevalence of types of operations was rather static, with repair with no ventriculotomy hovering around 20%.

What all these data tell us

Despite the fact that there is now a general appreciation of the importance of chronic pulmonary insufficiency after repair of tetralogy of Fallot and its potential impact on right ventricular size and function over a period of years,Reference Zahka, Horneffer and Rowe^4-Reference Davlouros, Karatza, Gatzoulis and Shore⁷ these data from both the North American and the European registries tell us that repair by means of right ventriculotomy with transannular patch is the most prevalent surgical technique. This technique is followed in frequency by repair with ventriculotomy and non-transannular patching. Repair without ventriculotomy accounts for less than one-fourth of primary repairs. It is important to note that of patients who undergo repair of tetralogy after previous palliation, the majority undergo transannular incision and patching at the time of eventual repair. Understanding that awareness of important late-phase events – re-operation, ventricular dysfunction, arrhythmias, and the risk of sudden cardiac death – undoubtedly influences patterns of referral and surgical practice, it is important to acknowledge that this awareness has not resulted in across-the-board diminution in the use of ventriculotomy incision or transannular patching. This is not because congenital heart surgeons have failed to explore the efficacy of other strategies or have failed to advocate for surgical techniques that maximise preservation of pulmonary valve competence whenever possible and minimise transannular and transmural right ventricular incisions whenever possible.

Some have hypothesised that a strategy in which one initially treats severely cyanotic and symptomatic infants by construction of systemic-to-pulmonary artery shunts with postponement of definitive repair until the age of 1 year may be accompanied by salutary increase in the Z-value of the pulmonary valve annulus during the interval period, theoretically making possible a reduction in the need for transannular patching.Reference Fraser, McKenzie and Cooley⁸ Although the frequency of reoperations during intermediate-term follow-up has been relatively low in some series of patients treated in this way, actual data regarding the question of disproportionate growth of the pulmonary annulus are limited, and the question has not been evaluated from a multi-institutional perspective.

The respective advantages of the so-called transatrial versus transventricular repair techniques remain a matter of controversy. Proponents of transatrial – or transatrial/transpulmonary artery – approach to repair of tetralogy of Fallot postulate that it would result in reduced incidence of right ventricular dilatation requiring later implantation of a pulmonary valve. The safety of this approach has certainly been demonstrated on the basis of excellent results with very low operative mortality achieved at several centres.Reference Padalino, Vida and Stellin^9, Reference Karl, Sano, Pornviliwan and Mee¹⁰ The results in Melbourne, Australia, over more than three decades have been outstanding, including one of the lowest rates of mortality in any large series of operations for tetralogy. D'Udekem and associates from Melbourne presented a comprehensive analysis of this cohort at the 2013 meeting of the American Association for Thoracic Surgery.Reference D'Udekem, Galati, Konstantinov, Cheung and Brizard¹¹ In this large cohort, transannular patching was performed in 75% of cases. What was most unique about this analysis was the observation that despite the fact that all surgeons used the transatrial repair technique, the rate of subsequent re-operations for either pulmonary insufficiency or right ventricular outflow tract obstruction varied considerably – and essentially inversely – between individual surgeons. The rate of re-intervention at 10 years varied among individual surgeons, between 8.8% and 26.7%. At 25 years, the overall freedom from re-operation was 75%.

It should come as no surprise that, regardless of what surgical approach is used for closure of the ventricular septal defect and division of septoparietal trabeculations, certain fundamental aspects of the outcome from surgery for tetralogy are inextricably related to the individual patient's underlying morphology: (1) certain patients have a sufficiently severe degree of hypoplasia of the pulmonary valve annulus that transannular incision simply cannot be avoided, except at the expense of nearly systemic-level pressure in the right ventricle; and (2) in many cases, the goals of achieving adequate relief of right ventricular outflow tract obstruction while maintaining competence of the pulmonary valve are mutually exclusive. As described by D'Udekem in relation to the Melbourne experience, even surgeons who consistently rely on transatrial approach to the ventricular septal defect, believing that this results in a smaller incision of the outflow tract and better preservation of right ventricular function, must decide how widely to open the right ventricular outflow tract, and how much of a residual pressure gradient across the outflow tract is acceptable. These general questions are more vexing than the question of how to approach the ventricular septal defect. They are probably also more important in the long run – and currently they remain unresolved.

Another technical issue relates to the question of what can be accomplished at the level of the pulmonary valve and annulus as an alternative to transannular incision. This falls under the general heading of “valve sparing” approaches to surgery.Reference Stewart, Backer, Young and Mavroudis¹² Numerous techniques have been utilised, but none, of course, are applicable to all patients. Surgical techniques, initially limited to extensive valvotomy and patch augmentation of the pulmonary trunk and sinuses, are now extended to include patch augmentation of the pulmonary valve, and also include interventional strategies such as intra-operative balloon dilation.Reference Robinson, Rathod and Brown^13, Reference Bacha¹⁴

For neonates with prematurity, low birth weight, severe hypoplasia of the pulmonary annulus and branch pulmonary arteries, or other factors that may be associated with increased risk of primary repair, the contemporary spectrum of palliative approaches includes innovative techniques such as transcatheter balloon dilation of the pulmonary valve or stent deployment in the right ventricular outflow tract, as alternatives to, or in addition to, surgical construction of systemic-to-pulmonary artery shunts.Reference Barron¹⁵

Finally, it is essential to acknowledge that the operation wherein patients with tetralogy of Fallot undergo closure of the ventricular septal defect and relief of the right ventricular outflow tract obstruction must be viewed as “reparative surgery” and not as “total correction”, the latter term having been used extensively during the 1980s. A rational approach to life-long care of patients who have undergone repair of tetralogy of Fallot in infancy is based upon regular evaluations and the recognition that appropriately timed subsequent procedures, such as surgical or transcatheter pulmonary valve replacement, are critically important and sometimes unavoidable in order to preserve right ventricular function and maximise the functional capacity of the patient.