MMCTS
(October 9, 2006). doi:10.1510/mmcts.2005.001487
Copyright © 2006 European Association for Cardio-thoracic Surgery
Procedure
Tetralogy of Fallot
Marco Pozzia,*,
Andrea Quartib and
Antonio F. Cornoa
a Alder Hey Royal Children Hospital, Cardiac Unit, Eaton Road, Liverpool, L12 2AP, UK
b Lancisi Hospital, Ancona, Italy
* Corresponding author: * Tel.: +44-151-2525715; fax: +44-151-2525643 E-mail: mpozzi75{at}hotmail.com
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Summary
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The optimal management of patients with tetralogy of Fallot has to consider the individual intra-cardiac anatomy as the most important variable, together with the age and the body weight of the patient. In any case the potential advantages of a primary early repair should be weighted against the experience and expertise of the individual centre and/or surgical team in dealing with tetralogy of Fallot and with neonates and infants. The best results are achieved by very carefully adapting the surgical technique to the individual morphology of the right ventricular outflow tract and of the pulmonary arteries. The details of the established surgical management for each component of the surgical repair are analysed and described. Over a period of 12 years (from 1993 to 2005) 318 consecutive patients with tetralogy of Fallot underwent repair with one hospital death (1/318=0.3% mortality).
Key Words: Congenital heart disease • Cyanosis • Surgery • Tetralogy of Fallot
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Introduction
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History
This condition was first described by the French physician Etienne Fallot, who published his findings in 1888.
In 1945 Alfred Blalock at Johns Hopkins University performed the first surgical palliative procedure, consisting in a systemic-to-pulmonary artery shunt between the transected right subclavian artery and the right pulmonary artery [1].
The first successful intra-cardiac repair was performed by Lillehei and Varco at the University of Minnesota in 1954 utilising human cross circulation [2].
In 1955 the first successful intra-cardiac repair with a pump oxygenator was performed by John W. Kirklin at the Mayo Clinic [3].
Since then, many contributions have been made to the surgical management of this cyanotic congenital heart defect [4,5,6,7,8,9,10,11].
Indication for surgery
Over the years there have been ongoing discussions on whether or not all patients with tetralogy of Fallot (TOF) should be primarily repaired or treated with a two-stage approach (palliative shunt followed by repair) at least up to 1–2 years of age.
TOF is not a fixed anatomical condition, but rather a spectrum (for practical reasons TOF with pulmonary atresia will be excluded from this chapter). As such, the surgical indication and the choice of surgical technique should be tailored to the individual anatomy and pathophysiology, rather than being considered the same for every patient.
Many patients with TOF have a satisfactory systemic arterial saturation at birth and in the first few months of life. Many clinicians consider this a reason to wait for surgery. In our opinion this is the ideal time to perform surgery. In these conditions the operation tends to be easier and the development of severe hypertrophy of the right ventricle can be prevented. Another reason is that early repair, providing adequate pulmonary blood flow, with homogeneous distribution to both lungs, allows normal growth and development of the pulmonary arteries. This is an advantage considering the potential negative effects on the pulmonary arteries of a systemic-to-pulmonary shunt.
Hypoxia ultimately progresses and when the systemic oxygen saturation decreases below the values of 75–80% operative intervention should be performed.
Not infrequently this condition can produce hypoxic spells. They can often be controlled medically with beta-blocking agents. If medical treatment is not sufficient, urgent operative intervention should be undertaken.
In our institution we would consider hypoplastic pulmonary arteries and/or long and narrow right ventricular outflow tract (RVOT) as unfavourable anatomic conditions for primary repair, and would opt for a shunt in the first 9 months of life. After the first 9 months of life or at any age in the absence of these unfavourable anatomical conditions, primary repair would be the preferred surgical option.
We would also delay the repair in the presence of anomalous coronary arteries and association with complete atrio-ventricular septal defect. In these cases, we would expect to use a biological valved conduit; because of this reason we would rather prefer to delay the repair until the body weight of the child is approximately 10 kg or more.
In any case the potential advantages of a primary early repair should be weighted against the experience and expertise of the individual centre and/or surgical team in dealing with TOF and with neonates and infants.
To summarise, in our institution palliative approach is currently considered in the following situations:
- Anomalous major coronary artery (<8 kg)
- Long and narrow infundibulum (<5 kg)
- Association with complete atrio-ventricular septal defect (<8 kg)
- Severely hypoplastic pulmonary arteries.
- Swiss cheese type of multiple VSDs (<10 kg)
Primary surgical repair would be indicated in all the other patients irrespective of age and body weight.
Diagnosis
For many years cardiac catheterisation (CC) has been considered the main tool to obtain the diagnosis and the required pre-operative information. In the recent years we are increasingly using the echocardiographic investigation as the main or only diagnostic procedure, associated with the clinical correlation. This is particularly true when it is possible to obtain good quality echocardiographic images in patients in the first few months of life. CT scan and MRI imaging are also becoming an increasing and attractive alternative to CC.
The information required prior to any surgical decision is:
- number and morphology of the ventricular septal defect(s) (VSD)
- morphology of the RVOT and pulmonary valve
- dimensions of the main pulmonary artery (MPA) and left and right pulmonary arteries (LPA and RPA)
- origin and position of the main coronary arteries
- presence of patent ductus arteriosus (PDA) and/or major aorto-pulmonary collateral arteries (MAPCAs)
- presence and type of associated cardiac malfor-mations.
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Surgical technique
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After opening the sternum a patch of autologous pericardium is harvetsted (Video 1).
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Video 1 We free a large area of pericardium and then we remove a large, rectangular patch, which is kept between two swabs in saline solution. We do not use glutaraldehyde.
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External examination
After the routine external examination to rule out the presence of anomalous pulmonary and/or systemic venous connections (the most frequent being the presence of persistent left superior vena cava, with or without presence of innominate vein), it is important to start with an accurate external examination of the heart, particularly of the RVOT (Videos 2 and 3).
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Video 2 The examination can reveal either the presence of anomalous coronary arteries or large coronary branches crossing the RVOT. They are not always easy to identify pre-operatively and their presence can still influence the surgical option (shunt versus repair) or the need for a biological valved conduit instead of a trans-annular patch, or simply influence the position and the direction of the right ventriculotomy.
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Video 3 Occasionally the external examination of the RVOT can show a transverse muscular area which becomes depressed with each systolic contraction: this is often a pretty good indication of the presence and location of muscle bands obstructing the RVOT and which need to be resected.
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It is also useful to examine the width of the external RVOT (= the area between the aortic valve and the left anterior descending coronary artery). This can be quite variable and when it is too narrow, it is often a good indication that the RVOT is hypoplastic and a trans-annular patch will be required. With this regard, see the differences between (Videos 2 and 3).
An inspection at the MPA and pulmonary arteries can also be useful to confirm the pre-operative information, in particular the presence and location of stenosis or hypoplasia of the pulmonary arteries.
In the presence of previous surgical systemic-to-pulmonary artery shunt(s) it is preferable to dissect and control it/them prior to beginning the cardiopulmonary bypass.
In the absence of a previous surgical shunt it is preferable to manipulate the heart as little as possible, in order to avoid or at least reduce the intensity of hypoxic spells. In this case, we would open the pericardium and place a purse string for cannulation of the aorta (Video 4) and one of the superior vena cava (SVC) prior to doing anything else.
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Video 4 The aorta is cannulated as high as possible and slightly towards the right side in order to leave as much space as possible to work on the pulmonary artery.
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The SVC and the inferior vena cava (IVC) are directly cannulated in order to have no cannulas interfering with the surgical exposure in the right atrium (RA).
Once on CPB, PDA and/or all surgical shunts are closed (Videos 5 and 6).
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Video 5 PDA and/or all surgical shunts are closed with metal clips or ligated and divided to prevent subsequent pulmonary artery distortion. Here you can see the dissection and clipping of a modified left Blalock-Taussig (B-T) shunt.
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Video 6 A right B-T shunt has been divided.
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The aorta and the pulmonary arteries are then dissected (Video 7).
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Video 7 The aorta is then completely dissected free from the MPA and the RPA. At the same time the LPA is dissected free up to the first lobar division. The RPA is dissected free only if there is a suspicion or a diagnosis of RPA stenosis.
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The operation is performed on mild hypothermia (body temperature lowered to 32–34°C) in the presence of the pulmonary arteries with adequate size. The body temperature is lowered to 28°C in the presence of substantial collateral flow and/or when a complex reconstruction of the pulmonary arteries is anticipated.
After cross clamping of the aorta and administration of the first dosage of blood cardioplegia (then repeated every 20 min), the RA is opened (Video 8).
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Video 8 The RA is opened with an oblique incision starting from the right auricular appendage and extending towards the area between IVC and atrio-ventricular groove.
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The left atrium (LA) is vented (Video 9). The exception is when either one can expect to have a large collateral flow or the LA appears to be distended as soon as the pericardium is opened. In this case the LA vent is placed directly into the LA through a purse string on the right upper pulmonary vein. In any case it is important to achieve a venous drainage sufficient to provide and maintain an empty RV.
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Video 9 A left atrium (LA) vent is placed through the inter-atrial septum after the right atrial opening; in the case of absent inter-atrial communication, a small surgical opening in the inter-atrial septum can be created as soon as the RA is opened.
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Sutures are placed on the right atriotomy as shown in Video 10.
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Video 10 Two stay sutures are placed on the anterior edge of the right atriotomy and another one on the posterior edge.
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The VSD is then inspected (Video 11).
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Video 11 The VSD is then inspected through a gentle retraction of the leaflets of the tricuspid valve (TV), in order to assess exactly its morphology and relationships with the aortic valve. It is not infrequent to find ridges and infoldings of muscle bundles in the proximity of the VSD, particularly in the area between 12 and 8 o'clock.
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Pericardial pledgeted suture(s) are very useful to improve the surgical exposure (Video 12).
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Video 12 Pericardial pledgeted suture(s) on the medial and occasionally on the anterior leaflets of the tricuspid valve are very useful to improve the surgical exposure.
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After the anatomical assessment of the VSD, the RVOT is inspected through the TV (Videos 13 and 14).
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Video 13 In the lower part of the RVOT there is often the presence of fibrous tissue, particularly in older patients. Through this approach it is also possible to visualise the pulmonary valve.
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Video 14 When this fibrous tissue is particularly prominent, it is removed first. In the older patients this procedure can produce quite a significant opening of the RVOT.
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The RVOT is then probed with a right angle instrument to identify the individual muscle bands. We would normally start from the parietal extension of the infundibulum, then address the muscle bands in the anterior wall of the RVOT and then assess the septal band, which we prefer not to divide if possible (Videos 15 and 16).
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Video 15 Once a muscle band is defined, with the probe still in place, it can be divided with a knife cutting the band until the probe is reached.
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Video 16 Then as much as possible of the band is resected with the scissors.
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One should be very careful in the resection to maintain a sizable muscle border with intact endocardium around the VSD. It is not difficult to get carried away and to resect a lot of muscle in the RVOT only to discover that there is little muscle around the VSD with no endocardium. This could make the closure of the VSD very difficult and unsafe.
At this stage it should be possible to visualise the pulmonary valve and, if necessary, perform a pulmonary valvotomy. We believe that, albeit possible, the exposure of the pulmonary valve is not ideal through the TV and we prefer to perform the pulmonary valvotomy through a longitudinal incision in the MPA.
The VSD closure is performed through the right atrial approach whether or not a trans-annular patch is used, because this approach allows to minimise the length of the right ventriculotomy (length only necessary to relieve the RVOT obstruction and not for the VSD exposure). In addition, with this approach, it is easier to preserve the integrity and function of the tricuspid valve. The VSD is generally closed with a patch of heterologous pericardium and running monofilament suture (Video 17).
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Video 17 First the patch is shaped and fixed on a towel.
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The VSD closure is shown in Videos 18,19,20,21,22,23,24,25.
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Video 18 The suture starts from the patch and then into the septum at 12 o'clock, and it goes from 12 to 8 o'clock. The patch is lowered down into the left ventricle in order to improve the surgical exposure of the edges of the VSD.
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Video 19 The running suture is continued until where the VSD reaches the leaflet of the TV. At this point the suture is passed through the TV and through the edge of the patient's pericardium. As it is not infrequent to find ridges and infolds of muscle bundles, particularly in the area between 12 and 8 o'clock, it is important to unfold this area (often by traction on the VSD patch already sutured in place) in order to visualise exactly the VSD edges and avoid residual VSD.
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Video 20 The suture is then restarted from 12 to 5 o'clock after having pulled the patch back into the RV and trimming it to adequate shape and size.
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Video 21 The sutures are placed in such a way to preserve the function of the chordae of the tricuspid valve.
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Video 22 When the postero-inferior rim of the defect is reached, care must be taken to place the suture away from the crest of the VSD and only on the right ventricular side in order to avoid any potential damage to the conduction system.
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Video 23 In the area between 3 and 5 o'clock it is possible to have chordae tendineae crossing the margins of the VSD. It is advisable to go underneath these chordae with the suture in order to preserve as much as possible the mobility and, therefore, the function of the TV.
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Video 24 Between 5 and 8 o'clock the suture is continued by sandwiching the leaflet of the TV between the patient's pericardium and the heterologous pericardium used to close the VSD. A strip of autologous pericardium is then cut, brought down to the TV and sutured on.
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Video 25 With a nerve hook the suture line along the VSD patch is checked and if there is any residual passage, it is closed with additional pledgeted sutures.
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The RVOT is then re-assessed (Video 26).
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Video 26 If the resection through the TV seems to have been sufficient, a Hegar dilator is introduced through the tricuspid valve and then through the RVOT and MPA to verify the obtained size and match it with the normal size for the age and the body weight of the patient. Through this approach it is also possible to size the LPA.
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If the RVOT is large enough, de-airing can be performed, the inter-atrial communication is closed and the aortic cross clamp is removed.
If the RVOT is not large enough or if there is a known obstruction at the level of the MPA or either pulmonary artery branch, these are addressed at this stage (Videos 27,28,29).
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Video 27 An incision is made in the main pulmonary artery and then extended into the LPA until the size of the vessel becomes bigger. Occasionally it might be necessary to extend the incision into the left lower lobe branch.
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Video 28 The incision in the main pulmonary artery is then extended proximally to the level of the pulmonary valve. Further resection of fibrous tissue in the subvalvular area is performed as well as a pulmonary valvotomy unless the size of the valve is clearly too small. Fused commissures are separated from the pulmonary artery wall and then divided. After the pulmonary valvotomy, the size of the PV is assessed with Hegar dilators.
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Video 29 If the obtained size is not large enough, the incision in the MPA is extended proximally across the PV annulus. Initially the incision is limited either to the fibrous tissue or extended into the RVOT for only 3–4 mm. The size of the RVOT is measured again. If it accepts the right size Hegar dilator, this suggests that the infundibular obstruction has been adequately relieved trans-atrially and no further extension of the incision is required.
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Not infrequently the LPA takes off from the MPA with a very acute angle, it is, therefore, necessary to reduce the angle with a series of sutures before reconstructing the LPA with a patch (Schematics 1,2,3).
In other cases the RVOT is hypoplastic rather than hypertrophic (Video 30).
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Video 30 If the RVOT is hypoplastic rather than hypertrophic the obstruction cannot be relieved from within the heart and the incision in the anterior wall of the RVOT is extended for the length of the infundibular septum plus 2–4 mm.
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Whenever possible the incision in the RVOT is placed directly through the anterior commissure of the PV to maintain adequate function of the PV leaflets, hence reducing the amount of PV regurgitation.
At this stage further resection of the RVOTO is performed through the RVOT (Videos 31 and 32).
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Video 31 First the fibrous tissue is resected.
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Video 32 Muscle bands are then resected until when it is possible to visualise the tricuspid valve.
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The RVOT and the LPA are then reconstructed (Video 33).
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Video 33 The RVOT and the LPA are then reconstructed, and for this purpose we prefer to use autologous pericardium.
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If there is a stenosis of the RPA we prefer to repair this stenosis either with autologous pericardium or with heterologous pericardium, but always using a separate patch from the one used to reconstruct the RVOT (Video 34).
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Video 34 Reconstruction of the RPA with a separate patch.
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After air evacuation from the left heart, the aortic cross clamp is removed and full re-warming is initiated. The right atriotomy is closed with a running monofilament suture.
The chest drainages are implanted, as well as two temporary pace-maker wires which are attached to the right ventricular wall and two to the right atrial wall.
After weaning from cardiopulmonary bypass the venous cannulas are removed, heparine is neutralised with protamine, and then also the arterial cannula is removed.
Intra-operative echocardiography and direct pressure measurements are used to rule out residual defects.
The pericardium is left open, and routine closure of the chest wall is accomplished with all absorbable sutures.
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Results
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- From May 1993 to December 2005, 318 consecutive patients underwent surgical repair for tetralogy of Fallot in our hospital. Patients with association of atrio-ventricular septal defect, pulmonary atresia or absent pulmonary valve have not been included in this review.
- The median age at repair was 13.1 months (range 8 days to 7 years), and the median body weight was 8.2 kg (range 3.6 to 24 kg).
- The age distribution was as follows: 36 patients (=11%) underwent repair within the first 6 months of age, 98 (=31%) between 6 months and 1 year of age, 92 (=29%) between 1 year and 18 months of age, 57 (=18%) between 18 months and 2 years of age, and 35 (=11%) between 2 and 7 years of age.
- Eighty-three patients (=26%) had a modified Blalock-Taussig shunt before repair, while the remaining 235 patients (=74%) underwent primary repair. The reasons for palliative surgical procedure were unfavourable anatomy (anomalous coronary artery, diminutive pulmonary arteries), and prematurity.
- In the total series there was one early death (1/318=0.3% mortality); this child died suddenly at home 16 days after surgery and autopsy ruled out any surgical problem.
- Median hospital stay was 8 days (range 5 to 54 days). All patients have been discharged in sinus rhythm. Right bundle branch block was present in 21.2% of the patients.
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Discussion
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Nowadays each institution is expected to compare its own results with the available literature and particularly with multicentre accredited database collections. In order to fulfil these expectations we have reviewed the most recent literature [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22] where the reported mortality is ranging from 0.8 to 7.0%, showing that our early mortality of 0.3% is more than acceptable.
With regard to the multicentre database, in Europe the gold standard is considered the EACTS congenital database. By analysing the EACTS results, combining all the procedures for repair of tetralogy of Fallot, with or without ventriculotomy, with or without trans-annular patch, with or without implantation of a valved conduit, the reported early mortality on 2213 patients is 63 deaths (=2.85%).
We should take into consideration that in the literature only the best results are generally reported, whilst the data collected in a recognised multicentre database, despite not being validated in all cases, offer a more realistic picture of the situation.
Based on this we can be satisfied with our early results.
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References
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- Blalock A, Taussig HB. The surgical treatment of malformations of the heart in which there is pulmonary stenosis or pulmonary atresia. J Am Med Assoc 1945;128:189–202.[Abstract/Free Full Text]
- Lillehei CW, Cohen M, Warden HE. Direct vision intracardiac surgical correction of the tetralogy of Fallot, pentalogy of Fallot and pulmonary atresia defects: report of the first 10 cases. Ann Surg 1955;142:418.[Medline]
- Kirklin JW, DuShane JW, Patrick RT. Intracardiac surgery with the aid of a mechanical pump-oxygenator system (Gibbon type): report of eight cases. Proc Staff Meet Mayo Clin 1955;30:201.[Medline]
- Barrat Boyes BG, Neutze JM. Primary repair of tetralogy of Fallot in infancy using profound hypothermia with circulatory arrest and limited cardiopulmonary bypass. A comparison with conventional two-stage management. Ann Surg 1973;178:406–411.[Medline]
- Castaneda AR, Lamberti J, Sade RM, Williams RG, Nadas AS. Open-heart surgery during the first three months of life. J Thorac Cardiovasc Surg 1974;68:719–731.[Medline]
- Coles JG. Transatrial repair of tetralogy of Fallot. Ann Thorac Surg 1995;59:1363.[Free Full Text]
- Corno AF. Tetralogy of Fallot in: Congenital heart defects. Decision making for surgery. Volume 1. Common defects. Steinkopff Verlag, Darmstadt, 2003;45–56.
- Fraser CD, McKenzie ED, Cooley DA. Tetralogy of Fallot: surgical management individualized to the patient. Ann Thorac Surg 2001;71:1556–1561.[Abstract/Free Full Text]
- Karl TR, Sano S, Pornviliwan S, Mee RBB. Tetralogy of Fallot: favorable outcome of nen-neonatal transatrial, transpulmonary repair. Ann Thorac Surg 1992;54:903–907.[Abstract]
- Pigula FA, Khalil PN, Mayer JE, del Nido PJ, Jonas RA. Repair of tetralogy of Fallot in neonates and young infants. Circulation 1999;100():II157–161.[Medline]
- Pozzi M, Trivedi DB, Kitchiner D, Arnold RA. Tetralogy of Fallot: what operation, at which age. Eur J Cardiothorac Surg 2000;17:631–636.[Abstract/Free Full Text]
- Dyamenahalli U, McCrindle BW, Barker GA, Williams WG, Freedom RM, Bohn DJ. Influence of perioperative factors in children younger than 18 months after repair of tetralogy of Fallot. Ann Thorac Surg 2000;69:1236–1242.[Abstract/Free Full Text]
- Hirsch JC, Mosca RS, Bove EL. Complete repair of tetralogy of Fallot in the neonate: results in the modern era. Ann Surg 2000;232:508–514.[CrossRef][Medline]
- Van Arsdell GS, Maharaj GS, Tom J, Rao VK, Coles JG, Freedom RM, Williams WG, McCrindle BW. What is the optimal age for repair of tetralogy of Fallot? Circulation 2000;102():III123–129.[Medline]
- Alexiou C, Mahmoud H, Al-Khaddour A, Gnanapragasam J, Salmon AP, Keeton BR, Monro JL. Outcome after repair of tetralogy of Fallot in the first year of life. Ann Thorac Surg 2001;71:494–500.[Abstract/Free Full Text]
- Turrentine MW, McCarthy RP, Vijay P, McConnell KW, Brown JW. PTFE monocusp valve reconstruction of the right ventricular outflow tract. Ann Thorac Surg 2002;73:871–879.[Abstract/Free Full Text]
- Alexiou C, Chen Q, Galogavrou M, Gnanapragasam J, Salomon AP, Keeton BR, Haw MP, Monro JL. Repair of tetralogy of Fallot in infancy with a transventricular or a transatrial approach. Eur J Cardiothorac Surg 2002;22:174–183.[Abstract/Free Full Text]
- Cobanoglu A, Schultz JM. Total correction of tetralogy of Fallot in the first year of life: late results. Ann Thorac Surg 2002;74:133–138.[Abstract/Free Full Text]
- van Dongen EI, Glansdorp AG, Mildner RJ, McCrindle BW, Sakopoulos AG, VanArsdell G, Williams WG, Bohn D. The influence of perioperative factors on outcomes in children aged less than 18 months after repair of tetralogy of Fallot. J Thorac Cardiovasc Surg 2003;126:703–710.[Abstract/Free Full Text]
- Kolcz J, Pizarro C. Neonatal repair of tetralogy of Fallot results in improved pulmonary artery development without increased need for reintervention. Eur J Cardiothorac Surg 2005;28:394–399.[Abstract/Free Full Text]
- Stewart RD, Backer CL, Young L, Mavroudis C. Tetralogy of Fallot: results of a pulmonary valve-sparing strategy. Ann Thorac Surg 2005;80:1431–1438.[Abstract/Free Full Text]
- Lee C, Lee CN, Kim SC, Lim C, Chang YH, Kang CH, Jo WM, Kim WH. Outcome after one-stage repair of tetralogy of Fallot. J Cardiovasc Surg (Torino) 2006;47:65–70.[Medline]
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Summary
Introduction
