The Ross-Konno Procedure in Children: Outcomes, Autograft and Allograft Function, and Reoperations

Transcription

1 The Ross-Konno Procedure in Children: Outcomes, Autograft and Allograft Function, and Reoperations John W. Brown, MD, Mark Ruzmetov, MD, PhD, Palaniswamy Vijay, MPH, PhD, Mark D. Rodefeld, MD, and Mark W. Turrentine, MD Section of Cardiothoracic Surgery, Indiana University School of Medicine, and James Whitcomb Riley Hospital for Children, Indianapolis, Indiana Background. The Ross aortic valve replacement with a modified Konno-type enlargement Ross-Konno procedure of the aortic annulus and subannular region allows an autograft aortic valve replacement for children with significant annular and subannular hypoplasia. The potential for growth and the proven durability of the autograft make the Ross-Konno procedure an ideal aortic valve replacement for this subgroup with multilevel left ventricular outflow tract obstruction. We reviewed our institutional midterm experience to assess autograft and homograft hemodynamics, and management after a Ross-Konno procedure. Methods. Between 1995 and 2005, 14 consecutive children (mean age, years; range, 1 month to 17 years) underwent the Ross-Konno procedure. All children had severe to critical aortic stenosis or multilevel left ventricular outflow tract obstruction. Results. There was 1 early and 1 late death with a mean follow-up of years. Actuarial survival at 10 years was 86%. Three patients underwent right ventricular outflow tract reoperation for conduit replacement for homograft dysfunction and one patient required redo aortic root replacement with a mechanical valves for progressive aortic insufficiency. Freedom from right ventricular outflow tract and autograft reoperation at 10 years is 77% and 92%, respectively. Aortic annular dilation was not observed in all patients. Univariate and multivariate analysis identified no risk factors for autograft or homograft valve-related reoperation. Conclusions. The Ross-Konno procedure is an excellent technique to treat complex multilevel left ventricular outflow tract obstruction in children with significant annular and subannular hypoplasia. The autograft demonstrated durability without development of aortic stenosis or progressive dilation and a low incidence of developing progressive aortic insufficiency. Enlargement of the aortic annulus appear to parallel somatic growth in most instances. (Ann Thorac Surg 2006;82:1301 7) 2006 by The Society of Thoracic Surgeons Complex left ventricular outflow tract obstruction (LVOTO) consists of a combination of a dysplastic aortic valve with hypoplastic aortic annulus and tunnellike fibromuscular stenosis of the subvalvular area. Initially, therapy may focus on the valvular level of obstruction using balloon valvuloplasty, open valvotomy, subvalvular muscle resection, or a combination of these methods. Regardless of the above procedures, the incidence of recurrent obstruction is high, and secondary acquired aortic regurgitation is also high. Aortic valve replacement (AVR) combined with resection or patch enlargement of the annular subaortic region is the definitive approach to relieve obstruction and regurgitation in this group [1 3]. The Ross procedure was first described in 1967 for the treatment of aortic valve disease in young adults [4]. Since that time, the Ross procedure has been increasingly applied to pediatric patients, including neonates and Accepted for publication May 3, Presented at the Poster Session of the Forty-second Annual Meeting of The Society of Thoracic Surgeons, Chicago, IL, Jan 30 Feb 1, Address correspondence to Dr Brown, Section of Cardiothoracic Surgery, Indiana University School of Medicine, 545 Barnhill Dr, EH 215, Indianapolis, IN ; jobrown@iupui.edu. infants. In recent years, the Ross-Konno procedure has emerged as the treatment of choice for the management of multilevel LVOTO [5, 6] in growing children. There are several advantages of the pulmonary autograft that benefit both the adult and pediatric patients. These advantages include an adequate midterm durability of the autograft, minimal risk of reoperation, and the lack of need for anticoagulation. In the pediatric population, there are additional benefits, including the diameter increase along with somatic growth. There are also disadvantages to the Ross procedure. The harvesting of the pulmonary valve necessitates putting two valves at risk, for a single valve disease. There have been a number of reports, predominantly in adults, describing dilation of the aortic annulus, sinuses of Valsalva, and sinotubular junction after the Ross procedure [7 9]. Some authors have reported that autograft dilation is a significant cause of aortic regurgitation [7], while others have not seen the progression of aortic regurgitation despite moderate growth dilation [8, 10]. Midterm and long-term data on infants and children with autograft and allografts undergoing the Ross- Konno procedure are lacking [11]. In an effort to understand the utility of the Ross-Konno procedure in this population, we retrospectively reviewed the group 2006 by The Society of Thoracic Surgeons /06/$32.00 Published by Elsevier Inc doi: /j.athoracsur

2 1302 BROWN ET AL Ann Thorac Surg ROSS-KONNO PROCEDURE 2006;82: Table 1. Associated Diagnoses Diagnosis of patients who underwent the Ross-Konno procedure at our institution. Material and Methods No. of Patients Aortic insufficiency 7 Atrial septal defect 5 Ventricular septal defect 4 Interrupted aortic arch/arch hypoplasia 4 Coarctation of aorta 3 Shone syndrome 3 Mildly hypoplastic left ventricle 2 Endocardial fibroelastosis 2 Supramitral ring 2 Mitral stenosis 1 DiGeorge syndrome 1 Between January 2005 and September 2005, 14 patients underwent a Ross-Konno procedure at Riley Children s Hospital in Indianapolis, Indiana. Two patients who underwent a Ross procedure without the enlargement of the LVOTO (previously Konno procedure with AVR) were excluded from this analysis. We reviewed the medical records with regards to the initial clinical features, pathophysiological findings, surgical treatment, and hospital mortality. Approval from the Indiana University Institutional Review Board was obtained for this study. The mean age at the time of operation was years (range, 1 month to 17 years) including two neonates and two infants. The mean weight was kg (range, 3 to 62 kg). All patients had severe to critical aortic stenosis. Associated lesions were common, with aortic insufficiency in 7 children (Table 1). Thirteen patients (93%) had undergone 25 interventions before their Ross- Konno procedure. The most common was a transventricular closed aortic valvotomy or balloon valvuloplasty through right carotid artery cut-down or open valvotomy (Table 2). At a mean time of years (range, 9 months to 10 years), no patient had been lost to follow-up. Operative Techniques Operation was performed through median sternotomy with cardiopulmonary bypass at a perfusate temperature of 26 C (Fig 1). Mean cardiopulmonary bypass time was minutes (range, 84 to 230), and mean aortic clamp time was minutes (range, 62 to 171). Myocardial protection was by means of a combination of cold antegrade and retrograde potassium blood cardioplegia with topical hypothermia using bicaval venous cannulation. Most patients received aprotinin 3.5 cc/kg, as an infusion, at the start of the procedure and 3.5 cc/kg, added to the pump prime to reduce postoperative bleeding and to reduce the inflammatory effects of bypass. After electromechanical arrest of the heart, the aortic valve was resected if it was not deemed repairable, and aortic root was calibrated with Hegar dilators. The pulmonary artery was transected at its bifurcation, and the pulmonary valve was inspected for defects. If no significant defects were found, the autograft was carefully harvested leaving a 1.5-cm anterior lip of subannular muscle for the Konno patch. Care was taken to avoid injury to the underlying left main coronary artery, left anterior descending coronary artery, and the septal perforators coming off it. The autograft was calibrated with a Hegar dilator that was 2 mm less than the calibrated autograft diameter on echocardiography. The diameter obtained was taken as the most accurate diameter as rigid dilators can stretch the autograft annulus. The autograft was placed in the right pericardial well while awaiting implantation. The aorta was then transected approximately 2 to 3 mm above the sinotubular ridge. The coronary ostia were removed with large buttons of aortic sinus tissue. If the annular difference was significant (more than 4 mm smaller than the pulmonary annulus), tailoring of the aortic root was accomplished by the Konno technique, namely, transecting the aortic annulus at the commissure between the left and right cusp or at a level just below the pulmonary annulus if the aortic valve is bicuspid. The autograft was then sutured to the widened aortic root placing the anterior tip of the retained right ventricular free wall to patch the triangular area created by transecting the aortic annulus. Pledgeted interrupted polypropylene mattress sutures were used for the proximal anastomosis. The right ventricular outflow tract (RVOT) was then reconstructed with an appropriately oversized cryopreserved pulmonary homograft (6 to 10 mm larger than the autograft) while the patient was being rewarmed. Cryopreserved pulmonary homograft (CryoLife, Marietta, Georgia) was preferentially used for RVOT reconstruction when available in appropriate size. Twelve patients Table 2. Previous Cardiac Procedures Operation No. of Patients Resection of the fibrous subaortic membrane 6 with/without septal myotomy Closed transventricular aortic valvotomy 4 Balloon valvuloplasty through right carotid 2 artery cutdown Patch aortoplasty 2 Coarctation repair 2 Atrial septal defect closure 2 Ventricular septal defect closure 2 Interrupted aortic arch repair 1 Aortic arch enlargement with pulmonary 1 homograft Apical aortic conduit 1 Open valvotomy 1 Supramitral ring resection 1 Total 25

3 Ann Thorac Surg BROWN ET AL 2006;82: ROSS-KONNO PROCEDURE 1303 received a pulmonary homograft ranging from 14 to 28 mm (mean, mm). One patient received a 12-mm Contegra conduit (Medtronic, Minneapolis, Minnesota), and 1 patient received a 27-mm decellularized pulmonary homograft (SynerGraft; CryoLife, Marietta, Georgia). The distal aortic anastomosis was completed last to allow good visualization of the distal pulmonary anastomosis. Inotropes were rarely needed despite long bypass and ischemic times, and most patients required vasodilators or beta blockers, or both, before being transferred to the intensive care unit. The aortic annulus in patients with a Ross-Konno procedure was enlarged from mm to mm (p 0.02). Statistical Analysis The SPSS statistical program for Windows version 10 (SPSS, Chicago, Illinois) was used to perform the data analysis. Data are expressed as mean and range. Actuarial estimates of freedom from postoperative events were accomplished with Kaplan-Meier methods, and p values for differences between distributions were obtained by log-rank testing. A forward step-wise selection method was used to add variables to the model, requiring significance at p less than 0.10 for entry and p less than 0.05 for retention. Early death is defined as death in the hospital or death within 30 days after the Ross-Konno procedure. All other deaths are considered late. Hospital mortality and freedom from reoperation were analyzed for the following potential risk factors: age, age less than 1 month, weight, sex, preoperative ventilatory support, endocardial fibroelastosis, presence of hypoplastic left ventricle, presence of mitral anomaly, presence of critical aortic stenosis, presence of other associated cardiovascular anomalies, presence of multilevel stenosis, left ventricular ejection fraction, peak transaortic valve gradient, postoperative pulmonary hypertension, postoperative extracorporeal membrane oxygenation (ECMO) support, and postoperative aortic regurgitation. Results Clinical Outcomes There was 1 early and 1 late death with a mean follow-up of years (range, 9 months to 10 years). Mean length of hospital stay was days (range, 7 to 44). One neonate with critical aortic stenosis underwent an emergent Ross-Konno procedure, aortic arch patch augmentation, and atrial and ventricular septal defect closure. This neonate required ECMO support and had intracerebral bleeding while being successfully weaned off from ECMO support 5 days postoperatively. The only late death occurred in a patient who had undergone a Ross-Konno procedure 5 months earlier, whose pulmonary valve homograft became severely insufficient and developed tricuspid regurgitation. This patient underwent replacement of the pulmonary homograft with a bovine pericardial valve as well as a tricuspid valvuloplasty, and died of aspiration pneumonia 2 months after RVOT revision. Overall survival estimated by the Kaplan-Meier method, including early mortality, was 86% at 1, 5, and 10 years. Univariate and multivariate analysis showed age less than 1 year (p 0.002) as the most sensitive predictor of mortality among patients with LVOTO who underwent the Ross-Konno procedure. Low cardiac output syndrome occurred in 2 patients (2 of 14; 14%) postoperatively and both required ECMO. One patient died (early death described above) and the other patient was successfully weaned from ECMO. Additional morbidity included prolonged ventilation (13 days) in 1 patient and complete heart block requiring pacemaker insertion in 1 patient (7%). The latter patient subsequently returned to normal sinus rhythm. Freedom From Reoperation Overall actuarial freedom from reoperation at 10 years is 69%. Three patients (21%) underwent RVOT conduit replacement for allograft dysfunction (one Medtronic Freestyle conduit, one Contegra conduit, and one bovine pericardial valve). The mean interval time for RVOT conduit replacement was years (range, 6 months to 7 years). One patient subsequently, 7 years after initial surgery, required aortic root replacement with a mechanical valve for progressive moderate aortic regurgitation. Actuarial freedom from reoperation at 10 years for the RVOT reconstruction is 77%, and for pulmonary autograft reoperation it is 92% (Fig 2). One patient (who had redo pulmonary valve replacement and who died at follow-up) also underwent tricuspid valve annuloplasty. One patient underwent left ventricular endomyocardial resection and left ventricle assist device insertion for 6 months for left ventricular diastolic dysfunction. This latter patient was a 12-year old with restrictive cardiomyopathy, pulmonary hypertension, atrial fibrillation, and atrial flutter who had been in congestive heart failure and who underwent a Berlin Heart left ventricular assist device implantation. While awaiting transplant, several echocardiographic studies and diagnostic cardiac catheterizations were obtained to evaluate heart function and pulmonary artery pressure. Gradual improvement was noted and patient successfully underwent left ventricular assist device explantation. Subsequent hemodynamic parameters and echocardiographic studies have remained favorable, and this patient remains in stable condition at 6 months of follow-up. Univariate and multivariate analysis identified none of the tested variables as risk factors for reoperation. All 12 surviving Ross-Konno patients are in New York Heart Association functional class I at latest follow-up, are doing well, and have not required anticongestive cardiac medications after the third postoperative month. Echocardiography Aortic and pulmonary valve function was described semiquantitatively at the last follow-up. Significant aortic stenosis has not recurred. Moderate aortic regurgitation developed in 1 patient (who has had reoperation). Six

4 1304 BROWN ET AL Ann Thorac Surg ROSS-KONNO PROCEDURE 2006;82: Fig 1. Ross-Konno procedure. (A) The aortic annulus is enlarged by incising the interventricular septum (dashed line) between the left and right commissures. The length of the incision is frequently limited to just beyond the annulus. A myectomy will also increase orifice area, limiting the extent of ventriculoplasty incision. (B) The autograft is sutured to the margins with interrupted pledgeted sutures. A short apron is left on the autograft to fill the ventriculoplasty site. (C) Coronary buttons are reimplanted into the autograft. (D) Completed reconstruction. patients with mild aortic regurgitation at last follow-up had trivial aortic regurgitation early after operation. These regurgitation jets have become mild by 2 to 5 years after Ross-Konno. The clinical status of these patients is excellent. None has a significant left ventricular outflow tract gradient (2 patients have an echocardiographicmeasured gradient less than 20 mm Hg). Aortic annular and sinotubular junction dilation were not observed in all patients. Overall at last follow-up, the diameter of the pulmonary autograft annulus increased from mm (at postoperative period) to mm (at last follow-up; p 0.03). Moderate or severe pulmonary regurgitation developed in 3 patients. All of them have had reoperation. Moderate pulmonary homograft stenosis developed in 1 patient with blood flow velocities between 3.5 and 4.2 m/s across the RVOT. Pulmonary stenosis has occurred in a second patient with a cryopreserved pulmonary homograft inserted at 7 years of age; the gradient is mild 4 years postoperatively. The clinical status of these patients is excellent. Comment Children with multilevel LVOTO consisting of supravalvular, subaortic narrowing, and aortic valve stenosis may require initial palliation to relieve one or more levels of obstruction. This may involve insertion of a supravalvular patch, open aortic valvotomy, closed transventricular or balloon aortic valvotomy for stenosis or subaortic

5 Ann Thorac Surg BROWN ET AL 2006;82: ROSS-KONNO PROCEDURE 1305 Fig 2. Freedom from right ventricular outflow tract replacement (diamonds) and pulmonary autograft replacement (squares) in children with Ross-Konno procedure. membrane and muscle resection. Often this initial approach will achieve long-term clinical improvement despite some degree of residual stenosis or insufficiency, avoiding a more extensive operation in the first years of life. This was the initial approach in the majority of our patients with multilevel aortic stenosis. In the past when the first option for an aortic valve substitute was a prosthetic valve, every effort was made to delay the operation as much as possible to allow for the patient s growth. The combination of subvalvular and valvular aortic stenosis may require an extensive operation including enlargement of the aortic root and aortic valve replacement. Several methods to enlarge the aortic root have been described; one is the anterior aortoventriculoplasty described by Konno and colleagues [12] in The advantage of the Konno technique is that it addressed all levels of LVOTO (namely, the diffuse muscular subvalvar stenosis, the small aortic annulus, and the small proximal ascending aorta). This technique achieved a larger increase of the left ventricular outflow tract than other techniques. In recent years the pulmonary autograft has emerged as an attractive valve for AVR, particularly in children and young adults. It has low thrombogenicity, low risk for infection, excellent hemodynamic performance, increase in diameter along with somatic growth, and longterm durability [13, 14]. With the experience gained from using prosthetic valves with the Konno aortoventriculoplasty, it was a natural evolution to use the pulmonary autograft with an anterior aortoventriculoplasty (Ross- Konno procedure) with excellent results in patients beyond the neonatal period [5, 6, 15]. Unfortunately, the urgent neonatal Ross-Konno operation still carries a significant mortality rate [6]. Clearly, with the experience gained from the prosthetic valve and Konno operation, our early experience with the Ross-Konno operation has been favorable with only 2 deaths. Some centers have advocated the Ross procedure as the first procedure for LVOT obstruction in infants and children. In the experience of Lambert and colleagues [16], the risk factors related to late mortality in Ross AVR were the young age at the initial Ross operation, and the number of prior aortic operations. With the Ross procedure, the LVOT gradient is almost always completely eliminated, and there is expected regression of left ventricular mass that should improve the long-term prognosis. The perioperative risk is higher for the Ross-Konno AVR in infants. We [17] and Van Son and associates [18] suggested that the first aortic valve procedure should be chosen according to the valvar anatomy, arguing in favor of valvuloplasty if the valve was trileaflet, but opting for insertion of the pulmonary autograft in the presence of a dysplastic bicuspid valves, if the surgical or balloon valvuloplasty fails to relieve aortic stenosis or excessive regurgitation. All patients in this study underwent a Ross-Konno procedure utilizing the root replacement technique. Other Ross techniques for this subgroup are not applicable. All patients had severe to critical aortic stenosis with associated hypoplasia of the aortic annulus and ascending aorta. A Morrow-type septal myomectomy may be added as necessary for subaortic obstruction. The Ross-Konno procedure has satisfactory rates of reoperation. In the pediatric population, Elkins and colleagues [14] have reported a freedom from reoperation of 90% at 8 years for the autograft and 94% for the homograft. These results must be tempered for the very young patient, who is rapidly growing and has limited thoracic volume for the placement of a pulmonary homograft. In the current study, 3 patients (21%) underwent RVOT conduit replacement for allograft dysfunction, and 1 patient required aortic root replacement with a mechanical valve using composite graft for a progressive moderate aortic regurgitation. Overall actuarial freedom from reoperation and from right ventricular to pulmonary artery (RV-PA) conduit replacement is good. Choice of the initial conduit and patient age impacted the need for replacement. Our preference has been to utilize an unaltered pulmonary homograft for RVOT reconstruction whenever an appropriate size graft is available. In addition, we strive to place the largest RV-PA conduit possible at the time of the Ross-Konno procedure. Our data support this practice. Other authors have found similar results for RVOT reconstruction. Tweddell and colleagues [19] reported factors adversely affecting homograft longevity with the use of aortic homograft rather than pulmonary homograft and smaller homograft size; and Homann and colleagues [20] demonstrated the superiority of homograft over xenograft in RVOT reconstruction. The orthotopic position of the pulmonary allograft may also increase its longevity in comparison with other RV-PA conduits. Laminar flow through a homograft in the pulmonary annulus may be less destructive to the valve than in situations where the flow must change direction, as in a conduit sutured to the RV infundibulum. Heterotopic placement of the RV-PA conduit also potentially subjects the graft to compression by the sternum. In addition, conditions requiring heterotopic placement of the RV-PA conduit, such as pulmonary atresia, may have other distal pulmonary artery abnormalities impacting conduit performance.

6 1306 BROWN ET AL Ann Thorac Surg ROSS-KONNO PROCEDURE 2006;82: There are potential disadvantages of the Ross-Konno procedure. The nature of the operation places two valves at risk for a single outflow tract disease. In addition, there have been a few reports, predominantly of adults, describing dilation of the aortic annulus, sinuses of Valsalva, and sinotubular junction after the Ross AVR [7 9, 21]. Some authors have reported that autograft dilation is a significant cause of aortic regurgitation [7], whereas others have not seen the progression of aortic regurgitation despite dilation [8, 9]. In those studies demonstrating progressive aortic regurgitation, the dilation of the sinotubular junction, which distracts the leaflets preventing coaptation, is thought to be the primary pathology. We did not observe any aortic annulus or sinotubular junction dilation in our patients with Ross-Konno procedure. In our experience, aortic annular and sinotubular junction dilation was observed in 2 patients who underwent Ross procedure without enlargement of LVOT (previously Konno procedure with AVR). Both patients required ascending aorta aneurysm resection for moderate (n 1) or severe (n 1) aortic regurgitation. Those 2 patients were not included in the current study. Early development of significant (moderate or severe) neoaortic regurgitation is usually associated with mechanical adaptation phenomena in the wall of the autograft associated with elastic fiber fragmentation [22, 23]. Ishizaka and associates [23] demonstrated severe elastin fragmentation in all excised pulmonary autograft walls during the valve-sparing aortic root replacement for dilation of the autograft and aortic regurgitation after the Ross procedure. It is obvious that the postoperative control of systemic blood pressure, thereby decreasing the wall stress, may be critically important. In our previous study [17], actuarial freedom from valve replacement was 96% and freedom from autograft reoperation was 92% at 10 years. In conclusion, our 10-year experience with the Ross- Konno procedure has shown good midterm results. The performance of the autograft in the children has been excellent. Despite the technically demanding nature of the operation, the rates of survival are high and complications are few. The outcomes, combined with the low rates of reoperation, make the Ross-Konno procedure an excellent option for this difficult patient population. References 1. Zeevi B, Keane JF, Castaneda AR, Perry SB, Lock JE. Neonatal critical valvar aortic stenosis: a comparison of surgical and balloon dilation therapy. Circulation 1989;80: DeBoer DA, Robbins RC, Maron BJ, McIntosh CL, Clark RE. Late results of aortic valvotomy for congenital valvar aortic stenosis. Ann Thorac Surg 1990;50: Brown JW, Ruzmetov M, Vijay P, Rodefeld MD, Turrentine MW. 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Successful aortic root remodeling for repair of a dilated pulmonary autograft after a Ross-Konno procedure in early childhood. Ann Thorac Surg 2004;78: Hraska V, Krajci M, Haun Ch, et al. Ross and Ross-Konno procedure in children and adolescents: mid-term results. Euro J Cardiothorac Surg 2004;25: Ishizaka T, Devaney EJ, Ramsburgh SR, Suzuki T, Ohyo RG, Bove EL. Valve sparing aortic root replacement for dilation of the pulmonary autograft and aortic regurgitation after the Ross procedure. Ann Thorac Surg 2003;75: