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The Department of Cardiac Surgery, The General Hospital, Southampton, United Kingdom
Received 15 July 2008;
* Corresponding author. Tel.: +44 1794340266; fax: +44 1793341090. (Email: monro1711{at}aol.com).
Key Words: Tetralogy of Fallot • Late outcomes
The article by Hickey et al. from Toronto [1] demonstrates in a large group of patients followed for up to 40 years why the operation should be called ‘repair’ rather than ‘correction’ of tetralogy of Fallot. More than 50% of the survivors of the initial operation have required further surgery during the follow-up period. They report a group of 1181 patients who were repaired between 1960 and 1998 and the fact that their outcomes can be presented in such detail is a tribute to the very impressive database that has been running in Toronto for many years. As Hickey et al. point out there are estimated to be 800,000 adults in the USA who have been operated on for congenital heart disease. There are many more worldwide and this has prompted a much-needed focus of care on this group of patients of which those with tetralogy of Fallot comprise a large number.
The early mortality during the 1960s in Toronto was as high as 25%, but down to 2% by the mid 1980s. Obviously this has a major effect on the overall survival, but it is interesting that among survivors it makes no difference in the long run whether they had a right ventricular patch, transannular patch or no patch during the repair. Unfortunately the operative details are really very limited and it is not clear whether the ventriculotomy was transverse or vertical or if there were any transatrial repairs. However as the presence or absence of a transannular patch does not seem to affect the long-term outcome, it would seem that conserving the valve ring often at the cost of a high postoperative pRV/LV ratio may not be such a good idea. Many patients with tetralogy of Fallot struggle in the first few hours and days postoperatively, and it is largely due to the improvements in postoperative care that the mortality has been reduced. If a relatively higher incidence of transannular patching is required to achieve a postoperative pRV/LV of perhaps less than 0.8 then it makes for an easier postoperative period without affecting the eventual outcome. However it would seem sensible not to use too large a transannular patch as this may cause so much pulmonary regurgitation that it affects the early postoperative course.
Many patients in the series were re-operated on for residual or recurrent right ventricular outflow obstruction and it might have been better to use more transannular patches. However great care must be taken not to cause a stenosis in the pulmonary artery at the distal end of the patch. Also of note in the series is a relatively high incidence of late repairs for right ventricular aneurysm (62 patients) and re-repair of ventricular septal defect (60 patients). However one must remember the long time-span of this series and they may have been in patients early in the series.
Pulmonary regurgitation is remarkably well tolerated for many years, but as Hickey et al. point out the volume overload causes right ventricular dilatation with poor function and tricuspid regurgitation. Widening QRS complexes greater than 180 ms may predispose to ventricular arrhythmias and sudden death [2]. Therefore the timing of pulmonary valve replacement is important and as yet not clearly defined. Certainly in an asymptomatic patient with a large right ventricle, a QRS complex greater than 180 ms would seem to be an indication for pulmonary valve replacement, as would increasing symptoms, right ventricular dilatation and severe tricuspid regurgitation. However we then have the dilemma of what to use for the pulmonary valve replacement. Traditionally the antibiotic sterilised homograft stored at 4 °C, either aortic or pulmonary did very well, but with cryopreservation of ‘fresh’ valves the possible increased immunological response seems to have resulted in less good long-term outcomes. Alternatively a heterograft can be used although we know that their longevity is limited and the patient will probably need several further operations for pulmonary valve replacement. Fortunately the risk of pulmonary valve replacement in this situation is low and Hickey et al. demonstrated a 20-year survival of 94%. Although the cardiologists are keen to use percutaneous insertion of valves in the pulmonary region, the dilated valve ring following repair of tetralogy of Fallot is not well suited to this ingenious technique [3].
It is interesting that so many patients in this series had previous palliation (53%). Certainly in the 1960s few surgeons had much success with repair in infancy but by the 1970s a number of surgeons were getting good results with repair even in early infancy [4,5]. It is therefore surprising that it was not until the late 1990s that the very skilled surgeons in Toronto changed their policy to early repair rather than palliation with improved survival. Therefore although the Toronto paper is a fascinating historical report, if one was to give an outcome prediction to the parents of a child about to undergo repair of tetralogy of Fallot today, one could be even more optimistic. Hickey et al. suggest a 90% survival at 40 years for an infant repaired in the late 1980s or early 1990s. A 97.8% survival has been reported at 20 years in a group of 89 infants [6], of whom 77% were urgent or emergencies and would probably have had initial palliation rather than repair in Toronto and indeed many other units. In that late death is relatively rare, with the modern trend to repair in infancy, a 40-year survival in excess of 95% is probable. However late re-operation for pulmonary valve replacement and recurrent stenosis will still be common and the parents should be warned of this and patients followed up carefully.
Early repair rather than palliation is becoming the norm now, but the trend to repair electively in the neonatal period or even first 3 months of life is probably unwise. Young infants tend to have a more difficult postoperative course with longer ventilation times and inotrope requirements. Better surgical techniques, understanding of the anatomy, cardiopulmonary bypass, myocardial protection and anaesthetics have all contributed to the good results. However it is probably the improvements in postoperative management that have been responsible for the good results in neonates and young infants that we see today. Since their change in policy in the late 1990s, the Toronto group suggest waiting until after 3 months for elective repair [7].
Like everything in life it depends what you start with, and it therefore comes as no surprise that patients with coexisting pulmonary atresia, absent pulmonary valve syndrome, atrioventricular canal, double outlet right ventricle, branch pulmonary artery stenosis and Down's syndrome have worse outcomes. It is unfortunate that in the paper by Hickey et al. all these conditions have been included in the total and it is therefore difficult to extricate results for the ‘classical, simple tetralogy of Fallot’. This group comprises by far the largest number among the 1181 patients in their report and it would be helpful to have detailed outcomes in this group alone for prognostic advice to parents. The last figure in their paper (4b) does show how good the results are in this group.
The repair of tetralogy of Fallot has been a major success story in cardiac surgery and is still a watershed between the straightforward and more difficult operations performed for congenital heart disease. The Toronto group are to be congratulated on the wealth of good long-term data in their large series of patients.
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