Tetralogy of Fallot: Current Surgical Management of an Old Problem
November 2005
The first anatomic description of Tetralogy of Fallot (TOF) appeared in 1671. Subsequently, this condition has become the most common type of cyanotic heart lesion, representing 8-10% of all congenital cardiac defects. The four features characteristic of TOF include subpulmonary stenosis, ventricular septal defect, overriding aorta and right ventricular hypertrophy (see graphic below). There is no specific etiology known to cause this disorder. However, a unified theory of conal truncal malformation during embryological development can be used to explain the entire spectrum of this abnormality.
The degree of right-to-left shunting and subsequent cyanosis that occurs in TOF is quite variable, ranging from acyanotic “pink tets” to severely cyanotic “tet spells.” The degree of right ventricular outflow tract (RVOT) obstruction determines the severity of right-to-left shunting. Anatomically, the obstruction can occur at the subvalvular, valvular and/or supravalvular level. In its milder forms, infants may present at several weeks or months of life with signs of heart failure (tachypnea, diaphoresis) as well as a characteristic harsh systolic ejection murmur. More severe forms present upon closure of the ductus arteriosus at several days of life, with cyanosis, respiratory distress and failure to thrive. Even in acyanotic disease, the potential risk of right-to-left shunting through the VSD, with subsequent risks of endocarditis and stroke, make complete correction advisable at an early age to avoid these devastating complications.
Surgical Repair of Tetralogy of Fallot
Complete surgical correction of TOF is approached via a right atrial incision and requires cardiopulmonary bypass and aortic cross-clamping. Resection of muscle from the RVOT is followed by patch closure of the VSD. Pulmonary valve repair and/or placement of a patch across the valve annulus (trans-annular patch) offers additional relief of RVOT obstruction. The most desirable surgical outcome includes relief of obstruction (with improved antegrade flow and pulmonary artery growth) combined with placement of a functional valve within the pulmonary circuit, thus preventing long-term right ventricular dysfunction and dysrhythmias. Intraoperative transesophageal echocardiography is used to confirm the adequacy of the surgical repair prior to leaving the operating room. The immediate postoperative course is typically characterized by some degree of right heart dysfunction due to muscle resection and preoperative hypertrophy. Early extubation is a desirable goal, as removal of positive pressure ventilation lowers intra-thoracic pressure and right heart efficiency is improved. This contributes to reduced dysrhythmias and inotropic use postoperatively.
Optimal Age for Tetralogy of Fallot Repair
The optimal age for repair of TOF has evolved from initial shunt palliation for relief of cyanotic episodes to more current approaches advocating complete correction in early infancy. Unfortunately, less favorable outcomes have been cited in the literature for infants undergoing primary correction at less than six months of age, particularly if pulmonary valve insufficiency occurs following the repair. The management approach used at California Pacific Medical Center has been one of early, complete neonatal/infantile repair. Minimally invasive techniques, including a small median sternotomy incision, use of intra-cardiac cameras (cardioscopy) and early extubation have become routine. A review of the surgical results of this approach to TOF was recently undertaken and presented in a peer-reviewed research symposium.
Review of Surgical Results
We identified all neonates and young infants with TOF operated between October 2002 and May 2005 at California Pacific. A total of thirteen children were identified, all undergoing primary correction without prior palliative procedures. The mean age at time of operation was 4.6 months (range 1-11 months) and the weight averaged 4.8 kg (range 2.8-7.9 kg). Importantly, ten of thirteen infants were under six months of age and weighed less than 5 kg. The integrity of the pulmonary valve was maintained in 11/13 patients, with residual, modest pulmonary insufficiency in two. The perioperative course was characterized by intra-operative extubation for a majority (7/12 with one chronically ventilated), including 3/5 infants under three months of age. Two additional infants failed extubation in the operating room. No patient required postoperative reintubation.
The most troublesome postoperative dysrhythmia—junctional ectopic tachycardia or JET—occurred in only one patient and was short-lived, responding to an Amiodarone infusion. Less than half of the patients (6/13) required two or more inotropes for cardiac support postoperatively. There was no operative mortality, bleeding requiring reoperation, stroke or sternal wound infection. The median postoperative length of stay was 6 days, ranging from 2-26 days (the child with the longest postoperative stay was recognized as having additional anomalies). Eight of 13 patients were discharged home by the sixth postoperative day.
Recently published results of TOF correction from the Society of Thoracic Surgeons’ (STS) national database for 2002-2003 report a mortality rate of 1.5% (1/68) for infants and 1.8% (4/226) overall. An additional published report of clinical outcomes in infantile TOF surgery indicates that California Pacific’s program, despite a younger age at the time of operation, compares quite favorably to much larger, established centers (van Dongen EI, et al. J Thorac Cardiovasc Surg 2003;126(3):703-710). California Pacific’s patients experienced greater valve salvage (84.6% vs 64%), an identical incidence of JET (7.7%), less mortality (0% vs 1%), and much higher rates of intraoperative extubation (58.3% vs. 1.3%). These findings indicate that primary infantile correction of TOF, using minimally invasive techniques, yields excellent results and is an optimal clinical management strategy. In contrast to a strategy of delayed surgical intervention until an arbitrary age or weight is achieved, our data contributes to the growing body of knowledge that early surgical intervention in obstructive heart lesions is the preferred approach. As surgeons continue to define a gold standard for the management of TOF, analyses such as this contribute to our understanding of this common lesion. Ongoing monitoring and STS reporting of California Pacific’s congenital cardiac surgery results—in combination with quality improvement methodologies—will enable enhanced benchmarking capabilities and promote the achievement of optimal outcomes for our patients for years to come.
This information provided by Michael Black, M.D.
Director, Pediatric Cardiac Surgery
Tel (415) 600-1KID (1543)