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Eur J Cardiothorac Surg 2005;27:975-979
© 2005 Elsevier Science NL
a Department of Cardiothoracic Surgery D6-26, Leiden University Medical Center, 2300 RC Leiden, The Netherlands
b Department of Pediatric Cardiology, Leiden University Medical Center, Leiden, The Netherlands
c Emma Children's Hospital/AMC, Amsterdam, The Netherlands
Received 21 September 2004; received in revised form 5 January 2005; accepted 12 January 2005.
* Corresponding author. Tel.: +31 71 5262348. (E-mail: m.g.hazekamp{at}lumc.nl).
| Abstract |
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Key Words: Congenital heart disease Ross procedure Aortic valve disease in children Autograft Homograft
| 1. Introduction |
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We have reviewed our consecutive Ross operations in all patients younger than 18 year with an emphasis on maximal pulmonary autograft diameters in relation to body surface. Part of our experience has been described previously [11].
| 2. Material and methods |
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Thirty-seven patients (70%) had undergone surgery or percutaneous intervention(s) prior to the Ross procedure (Table 1). Of this group 11 patients (20%) had undergone more than one procedure prior to the pulmonary autograft procedure.
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2.2. Operative technique
In all patients the pulmonary autograft was implanted using the root replacement technique. Reinforcement of proximal and distal suture lines with a strip of autologous pericardium was used in most patients. Continuous sutures were used in all. In all cases cardiopulmonary bypass with moderate hypothermia was used. Autograft harvesting was usually performed after aortic cross-clamping and antegrade administration of St Thomas cardioplegic solution. The mean cross-clamp time was 113min (range: 69189min). Right ventricular outflow tract (RVOT) reconstruction was performed with cryopreserved pulmonary homografts (N=47; mean diameter 22mm), cryopreserved aortic homografts (N=3; mean diameter 15mm) or Contegra® bovine jugular vein grafts (Medtronic Inc., Minneapolis, MN, USA) (N=3; mean diameter 15mm). The distal RVOT suture line was usually done during myocardial arrest while the proximal suture lines were performed on beating heart.
In 13 patients (25%) the aortic annular or LVOT diameter was considered as being too small and annular enlargement was performed in association with septal muscle myectomy and/or resection of subaortic fibrous tissue. In 3 of this 13 patients the LVOT was further enlarged by septal patch insertion (RossKonno procedure).
Associated procedures during the Ross operation were enucleation or resection of a discrete subaortic stenosis in 8 patients, ventricular septal defect (VSD) closure in 2 patients and mitral valve replacement in one patient. One patient with a VSD and aortic insufficiency repaired has previously been described elsewhere [12].
2.3. Follow-up
Follow-up was performed by analysis of operative reports, patient records and echo-Doppler studies at last follow-up. Body weight and length data at the time of last follow-up were collected and used to determine body surface area (BSA; m2). The maximal diameter of the pulmonary autograft at sinus of Valsalva (SOV) level obtained by echocardiography was noted of the same last visit. Maximal autograft diameters were indexed for BSA and compared to normal values for aortic SOV diameters in relation to body surface area and age, as indexed by Roman [13]. The degrees of pulmonary autograft and RVOT conduit insufficiency were indexed as being trivial, mild, moderate or severe. Gradients over the LVOT and RVOT were expressed in maximal Doppler gradients (mmHg).
Of the 47 surviving patients 5 were lost to follow-up. Four of these patients came from non-European countries. With the exception of these 5 patients, recent follow-up data were available in all other patients.
2.4. Statistical analysis
Statistical analysis was performed with the use of SPSS-11. Descriptive statistics are expressed as median and range. Means are provided with standard deviations. Unpaired student t-test was used for comparison of unpaired data. P<.05 was considered to indicate statistically significant difference. The KaplanMeyer method was used to determine event-free survival curves.
| 3. Results |
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3.2. Early mortality
Early mortality occurred in 3 patients (5.6%) at the age of 1, 2 and 4 months. One neonate with critical valvular AS developed massive AR directly after balloon dilatation and underwent a Ross procedure on an emergency basis. This patient died in the intensive care unit as a result of multiple organ failure. Two other infants had been referred with LVOT obstruction following previous repair of interrupted aortic arch and VSD, 1 and 3 months before the Ross operation. One of them died as a result of preoperative poor left ventricular (LV) function. The other patient developed myocardial ischemia related to the coronary artery reimplantation and died early.
3.3. Late mortality
Three patients died 13 months, 5 and 6 years after the Ross operation (5.6%). One patient with valvular AS received a Ross procedure at the age of 2.5 months following a failed attempt of balloon dilatation. Severe pulmonary hypertension persisted after surgery and this patient died 13 months later. A second patient received a Ross procedure at the age of 7 years but suddenly died at 5 years of follow-up. Pulmonary hypertension had been diagnosed in this patient several years postoperatively. In these 2 patients autopsy showed severe LV endocardial fibroelastosis. LV dimensions were within normal limits at the time of the Ross procedure. A third patient had a Ross operation at the age of 16 years. Pulmonary artery patch augmentation was performed after one year to relief distal RVOT homograft stenosis. Complications of stent placement for recurrent RVOT obstruction subsequently led to mortality 6 years after the Ross procedure.
3.4. Reoperation
A total of 8 patients needed reoperation. Five patients (9.4%) were reoperated for insufficiency and/or dilatation of the pulmonary autograft. Two patients were reoperated for valvular failure of the pulmonary autograft. One patient presented with a valvular insufficiency 3 years after the Ross procedure: at reoperation a delineated perforation near the hinge of the right coronary autograft cusp was observed and subsequently repaired with an autologous pericardial patch. A second patient returned with fibrosis and shortening of one the autograft leaflets 2 years after the Ross procedure. In this patient who had undergone an arterial switch operation in the past, an insufficient aortic valve had been replaced by the pulmonary autograft that in fact was the aortic valve before the arterial switch operation [14]. At reoperation the autograft was replaced by a mechanical prosthesis.
Autograft dilatation with mild to severe AR led to reoperation in 3 patients. Maximal autograft diameter (at sinus Valsalva level) was 63mm in one patient. This patient underwent a Bentall procedure with insertion of a mechanical valve prosthesis. Mechanical valve replacement was performed in a second patient and valve sparing root remodelling was done in the third patient. The age at the time of the Ross procedure had been 5.5, 3, and 6 years, respectively.
Three patients were reoperated for right-sided homograft obstruction. Two homografts were replaced 5 and 8 years after the Ross operation (Ross performed at the age of 1 month and 4.8 years, respectively). In a third patient distal homograft obstruction required patch enlargement 1 year after the Ross procedure.
3.5. Midterm survival
KaplanMeyer analysis showed a survival and event free survival rate of 89 and 74% at 9 years of follow-up, respectively (Fig. 1).
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3.7. Autograft function
Maximal autograft diameters (at sinus level) were indexed to body surface area (m2) and compared to normal values for aortic root diameters in infants, children and young adults (Fig. 2). At last follow-up 90% of autograft diameters indexed to body surface area was above the 90th percentile of normal aortic root diameters. Median diameter was 37mm (range: between 22 and 45mm). Bicuspid aortic valve vs. tricuspid valve showed no significant difference for risk of developing aortic root dilatation (P=0.218).
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3.8. Homograft function
RVOT obstruction was rare in our patients; in only 3 cases a moderate degree of stenosis was noticed, with a maximum Doppler RVOT gradient ranging between 37 and 45mmHg. Mean maximal RVOT gradient of the entire population was 23mmHg, ranging between 7 and 45mmHg. Moderate homograft insufficiency was observed in only 4 patients, while 13 patients had only trivial to mild homograft regurgitation.
| 4. Discussion |
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When aortic valve replacement in children can no longer be postponed, replacement with the pulmonary autograft has important advantages. The use of anticoagulants can be avoided as well as the occurrence of early failure as observed with homografts in children. Above all the autograft increases in size commensurate with body growth [10]. Therefore, the pulmonary autograft is superior to any other available aortic valve substitute for the growing child. Alternative surgical options to the Ross procedure should however, always be considered. Mechanical valves can be used in older children if a size of 21mm or larger can be inserted. Severe LVOT obstruction can be repaired sometimes without the need for aortic valve replacement. However, in our series aortic valve pathology or hypoplastic annulus was present in all RossKonno patients.
During our 10-year experience we came across some additional technical benefits of the Ross procedure. Enlargement of annulus or septum which is often required in congenital aortic valve disease, is easily accomplished when the root is removed and may be accomplished without the insertion of patch material, using the extended muscular rim of the autograft. Moreover, any associated subaortic VSD can be addressed in a similar fashion by using the muscular rim of the autograft to make an extended inflow anastomosis including the VSD [12]. In tunnel-form LVOT obstruction incision of the muscular septum and subsequent enlargement with patch material (RossKonno procedure) will provide a satisfactory solution in almost all cases.
In one patient with neo-aortic valve insufficiency following the arterial switch operation a switch-back procedure was performed. The valve was replaced with the neopulmonary valve, which originally was the anatomic aortic valve. Bringing back the native aortic valve to the left ventricle certainly has a lot of intuitive appeal [14].
Early mortality in our series occurred only in neonatal patients or young infants. Six patients underwent the Ross procedure at an age of 3 months or less. Mortality in this age group was relatively high with 4 of 6 patients dying (three in-hospital deaths and one late death). One patient died as a result of multiple organ failure following an emergency Ross procedure. Balloon dilatation had resulted in severe aortic valve insufficiency and cardiac arrest. Two patients had valvular and subvalvular LVOT obstruction following repair of interrupted aortic arch type B and VSD 1 and 3 months earlier. One of them had severely depressed left ventricular function and died of low output failure following the Ross procedure. Ischemia probably caused by unrecognised left coronary artery kinking led to mortality in the other patient with previous IAA/VSD repair. Finally, one patient died 13 months after a Ross procedure (performed at the age of 2 months) due to severe pulmonary hypertension and left ventricular failure. Autopsy confirmed the presence of severe left ventricular fibroelastosis. Prior to the Ross operation diastolic LV dysfunction with a minor suspicion of fibroelastosis was present. LV-dimensions were within normal ranges.
LVOT obstruction following IAA/VSD repair is common and the use of the RossKonno procedure is very attractive. Care should be taken with coronary artery transfer as the diameter of the pulmonary autograft will usually be considerably larger than that of the aortic root. Starnes reported their experience with the pulmonary autograft procedure for residual LVOT obstruction following IAA/VSD repair with good results. They even suggest that for IAA/VSD and small LVOT a primary RossKonno procedure with arch repair may be the procedure of choice [2,1517].
Endocardial fibroelastosis has been reported as being a risk factor for an adverse outcome in neonatal critical aortic stenosis [18]. Biventricular repair may not always be the ideal solution for this subgroup and the Norwood procedure and subsequent univentricular repair can be a better option.
Dilatation and autograft valve failure as has been described in several series of adult patients [38] also occurred in our pediatric population. The majority of patients showed annular diameters in excess of 90th percentile of normal aortic root diameters and 3 patients were even reoperated for valve failure in association with excessive root dilatation. The meaning of this observation is not clear, as progression of autograft dilatation was not common in this series. Serial assessment by echocardiography and careful clinical follow-up will provide more insight in the coming years. Although exact criteria for reoperation because of dilatation are not available, the rate at which dilatation occurs and maximal diameter related to body surface area should be taken in consideration.
In some patients the superior capacity of juvenile tissues to remodel appears to be inadequate to prevent aneurysmal dilatation and valve failure of the pulmonary autograft. Although one might believe that a Ross procedure performed in the neonatal period would suffer less from autograft dilatation than a Ross performed at a later age, some evidence exists that autograft dilatation can also occur following a neonatal Ross operation (Ziemer, personal communication 2003). Initial bicuspid aortic valve appeared to be no risk factor for developing dilatation either; despite suggestions in literature our study showed no difference in dilatation between the two groups [19].
Reinforcing proximal and distal autograft suture lines with autologous pericardial strips was used in most of our patients, but apparently did not provide protection from dilatation. The use of large coronary buttons to replace the native pulmonary sinuses and reinforcement of the non-coronary sinus wall of the pulmonary autograft by leaving the noncoronary aortic sinus in situ, have been reported to be of benefit [20].
Root dilatation is not the only mechanism of autograft failure. In one of our patients leaflet fibrosis occurred leading to replacement by a mechanical prosthesis. Leaflet dysfunction without associated root dilatation has been described by others before [21]. The mechanism of autograft leaflet shortening by fibrosis is not known. It may be the result of improper tissue handling at the time of operation but autograft leaflet failure may also be the result of a (connective) tissue disorder.
In summary, we believe that the Ross procedure is of great use in the pediatric population as it provides a unique growing aortic valve substitute together with the above-described additional technical advantages such as an adequate solution for otherwise difficult to treat obstructive LVOT's. Nevertheless, in our opinion the Ross procedure should only be considered when valve-sparing techniques can no longer provide a solution for pediatric aortic valve disease.
| Footnotes |
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Presened at the joint 18th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 12th Annual Meeting of the European Society of Thoracic Surgeons, Leipzig, Germany, September 1215, 2004. | References |
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