INTRODUCTION

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, accounting for 10% of congenital heart defect patients and occurring in one in 3,600 births^[1]. The 10-year survival rate in untreated patients is 24% only^[2].

The basic anatomical defects stem from the anterior and cephalad deviation of the infundibular septum. Less severe right ventricular outflow tract (RVOT) obstruction or associated major aortopulmonary collaterals may lead to delayed appearance of symptoms, and thus late presentation of patient for evaluation. Only a minority of patients with unrepaired TOF reach adulthood without symptoms or complications such as haemoptysis, intracerebral abscesses, etc. In developing countries like India, it is common the late presentation of TOF patients to a hospital as compared to that of developed countries, which may be due to financial constraints, neglecting symptoms in poor socioeconomic strata patients, delayed referral to tertiary care centre, and limited availability of paediatric cardiac surgery centres.

Nevertheless, the natural history of the chronic hypoxia that characterizes TOF is responsible for a variety of complications such as cerebral complications, myocardial dysfunction, and propensity to ventricular arrhythmias^[3-5].

We performed a retrospective analysis of total correction for TOF in adults with age > 15 years to analyze surgical outcome in this specific subset of TOF.

METHODS

A retrospective descriptive study was designed to study the in-hospital outcome of all the adult patients who had undergone intracardiac repair for TOF from January 2015 to January 2020 at Atal Bihari Vajpayee Institute of Medical Sciences (or ABVIMS) and associated Dr Ram Manohar Lohia Hospital (New Delhi, India), a tertiary care centre.

A total of 362 cases of complete repair for TOF were performed during this interval in our centre, out of which 45 were adult TOF patients, i.e., age > 15 years (12.43%). All symptomatic patients with defined age criteria diagnosed with TOF and having favorable anatomy for complete repair for TOF were included in our study. TOF/pulmonary atresia and TOF/pulmonary atresia/major aortopulmonary collateral arteries requiring unifocalization or those requiring palliative shunt for severe cyanosis at presentation to us were excluded from the study. Epidemiology, symptomatology, and preoperative evaluation using routine echocardiography (ECHO) and cardiac catheterization (CATH) were done in all patients. Routine follow-up with weekly follow-up for six weeks, monthly follow-up for six months, following half yearly follow-up were done.

RESULTS

A total of 45 patients were included in the study from January 2015 to January 2020. Males comprised the majority of patients (33 [73%]); 12 (27%) were female. The median patient age was 21 years (range 15-44 years). Two patients (4%) had a modified Blalock-Taussig shunt placed in infancy at another centre.

The preoperative characteristics of the patients included in the study is shown in Table 1.

Table 1 - Preoperative characteristics of the patients included in study.

Nineteen patients (42.2%) had aortopulmonary collaterals significant enough to warrant preoperative coiling. ASD was present in 15 patients who underwent surgery (33.33%). Seven patients had placement of a transannular patch; in those with a pulmonary valve annulus Z-score <-2, the PFO was left open. Patent ductus arteriosus was noted in 15.5% of patients and it was ligated. A total of 42 (93.33%) patients had a subaortic VSD, while three (6.6%) patients presented with a doubly committed VSD.

The most common type of RVOT obstruction was combined infundibular and valvar type accounting for 34 cases (75.5%). In six patients (13.3%), RVOT obstruction was pure infundibular, while three patients (6.6%) had pure valvular obstruction. Two patients had localised hypoplasia of MPA or ostial stenosis at one or both of the branch PAs for which pericardial patch augmentation was done.

One patient had the left anterior descending coronary artery crossing RVOT and trans-RA total correction was done successfully.

As our institutionally preferred approach, we performed a trans-RA repair in 33 patients (73.3%), while a right atrium-PA approach was used in five patients (11.1%). A limited right ventriculotomy was done in the few patients who had placement of a transannular patch. Also, three patients that had significant residual gradients across the area of PA patch augmentation required revision prior to chest closure. One required revision of the MPA patch, one of the MPA-left PA patch, and one of the MPA-right PA patch.

Table 2 shows the surgical data and Table 3 describes the postoperative complications encountered. The most common complication in the postoperative period was right bundle branch block (RBBB), seen in 14 patients (31.1%). Two patients required reoperation for bleeding, and we had one early postoperative death (2%), attributed to right ventricular (RV) dysfunction with junctional ectopic tachycardia (JET). In our initial experience, there were six patients who required reinstitution of CPB for inadequate RVOT resection; based on P^RV and P^LV assessment (P^RV:P^LV > 0.8 )and hemodynamic considerations.

Table 2 - Surgical data.

An intraoperative picture can be seen in Figure 1.

Fig. 1 - Intraoperative picture.

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Fig. 1 - Intraoperative picture.

Table 3 - Postoperative complications.

Since instituting the JIRAAT for evaluation of the adequacy of RVOT resection, no patients have required intervention for residual RVOT obstruction.

The average hospital length of stay in our study was five days (± 2 days).

A routine postoperative ECHO was performed in all patients prior to discharge and a satisfactory result of VSD closure with adequate RV coring was uniformly achieved in all patients.

DISCUSSION

A subset of patients with TOF and minimal RVOT obstruction present in early adulthood^[1,2,6].

Of the 362 patients that had complete repair of TOF in our centre over the study period, 45 (12.43%) were adults. These patients face effects of prolonged cyanosis resulting into RV hypertrophy, polycythemia, coagulation defects, and the development of extensive bronchial collaterals^[3].

Complete clinical evaluation gives insight for the planning of intervention as well. Cardiac CATH and angiography are important diagnostic modalities for characterizing the cardiac and vascular anatomy and physiology in patients with TOF. This is especially true when planning a complete repair for patients with long-standing cyanosis and the development of extensive bronchial collaterals^[5,7]. At our centre, we have made it an institutional policy of performing routine CATH study prior to operative intervention in adult TOF. In our study, 19 patients (42%) had significant aortopulmonary collaterals on evaluation necessitating coiling by cardiologist preoperatively.

We achieved excellent early and midterm survival results and significant improvement in functions and disease-free quality of life. We had 2% mortality rate in early postoperative period compared to standard 3-4% mortality in other study groups^[4-11].

Significant RV hypertrophy due to chronicity of disease necessitated adequate myocardial protection and we used routinely Del Nido cardioplegia with timely repeat whenever needed along with cold hypothermia^[9,10].

Our routine and preferred approach via a transatrial correction of the TOF is associated with excellent early and midterm results.

Our results confirm that this approach is safe (low mortality), and it also contributes to the preservation of satisfactory RV function by preserving the pulmonary valve and avoiding ventriculotomy^[10]. Mean RVOT gradient was 12 in postoperative ECHO which was comparable to other studies^[4,5,6,12].

Moderate PR was seen in two patients, while none had severe PR. Serial ECHO follow-up was done in these patients to monitor RV function and reintervention was not indicated in either of patients based on symptomology or progression of RV dysfunction in serial follow-up. Mild TR was seen in one postoperative patient, while there was no progression of TR in routine postoperative follow-up in the remaining patients. Strict fluid restriction and diuretics were given in follow-up. Trans-RA approach also resulted in lesser incidences of rhythm disturbances. One patient went into JET in postoperative period, while 14 patients had RBBB in postoperative period.

Ventriculotomy was needed only on indication of pulmonary valve repair and transannular patch correction when needed. VSD should be closed rigorously with interrupted reinforced sutures due to decreased tolerance of any residual VSD in TOF patients^[13]. Our transatrial approach for VSD closure achieved 100% successful repair. We routinely used antifibrinolysis drugs to combat higher bleeding tendency^[10].

Adequacy of RVOT resection was established by JIRAAT, devised by our own institution, which resulted into satisfactory results and improved postoperative outcome^[14].

Transannular patch placement was necessary in seven (16.2%) patients, a reduced number compared to those reported by other groups^[14-16]. Postoperative pulmonary insufficiency (PI) is a common and anticipated sequela of this approach. Of the seven patients who had transannular patch placement, five were left with mild PI, and two with moderate PI. We did not have any patients that demonstrated severe PI. We had one early death resulting from severe RV dilatation and dysfunction and associated JET. This patient belonged to the transannular patch group, had a loss of atrioventricular synchrony with tachycardia, and was refractory to Amiodarone therapy. Most of the evidence in the literature pointed out the benefits of timely repair of any significant pulmonary or tricuspid valve dysfunction^[17-18].

CONCLUSION

Using JIRAAT for adequacy of infundibular resection, complete repair of TOF can be performed successfully with minimal residual outflow tract obstruction and low mortality.