The optimal surgical treatment of children with congenital

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1 Aortic Valve Repair of Congenital Stenosis With Bovine Pericardium Michael J. Tolan, FRCS(I), Piers E. Daubeney, MB, BS, Zdenek Slavik, MD, Barry R. Keeton, FRCP, Anthony P. Salmon, FRCP, and James L. Monro, FRCS Wessex Cardiothoracic Centre, General Hospital Southampton, Southampton, England Background. Conservative surgical options in the treatment of congenital aortic stenosis are limited. To relieve the obstruction necessitates full incision of the raphe of the larger valve leaflet, but this inevitably causes prolapse. Methods. We performed aortic valve repair in 6 children, aged 14 months to 17 years, with congenital aortic stenosis, 2 having had aortic valvotomy as infants. The repair consisted of suturing the base of a triangular piece of bovine pericardium, with a simple vertical fold, to the free edges of the incised raphe. The pericardial fold was then sutured vertically to the aortic wall. Results. At follow-up of 2 to 60 months, the mean peak systolic Doppler gradients had decreased from mm Hg to 26 9 mm Hg. The effective valvular orifice area increased from 33% 6% to 64% 3%, allowing blood flow to increase by a factor of Two patients have mild and 2 have mild-to-moderate aortic regurgitation. Conclusions. The described conservative repair renders the valve tricuspid and trisinusoidal, and the deficient interleaflet triangle is recreated, preventing cusp prolapse. Longer follow-up is required to assess the durability of unstented pericardium in the aortic position, but the early results are encouraging. (Ann Thorac Surg 1997;63:465 9) 1997 by The Society of Thoracic Surgeons The optimal surgical treatment of children with congenital aortic stenosis remains unresolved in many instances [1, 2]. It is generally accepted that cardiac valve repair is preferable to replacement [3], although recent literature concerning aortic valve replacement with pulmonary autografts is impressive [4 6]. Some authors recommend pulmonary autograft replacement of the aortic valve in the presence of a nontricuspid aortic valve and after failed surgical valvuloplasty [7]. The aortic valve in congenital bicuspid stenosis has unique pathologic features [8], which must be considered in any attempt at repair. In a study of bicuspid valves [9], the circumferential amplitude of the smaller leaflet ranged between 120 and 180 degrees, one leaflet being larger in 85% of valves. A raphe, or as it is otherwise called the rudimentary commissure, was present in 84%, defined as a fibrous ridge at a right angle to the circumference of the leaflet dividing the leaflet into two component parts. Incising the raphe, recommended by some, provides a large central opening and a better blood flow pattern but is usually associated with severe regurgitation. The shallow, unsupported cusps tend to prolapse into the ventricular cavity, and there is poor coaptation with the opposite cusp. With time, lengthening and redundancy of the valve occurs, leading to prolapse and further insufficiency not only at the commissure but also throughout the whole valve. It has been suggested that the sinuses of Valsalva play Accepted for publication Sep 7, Address reprint requests to Mr Monro, Wessex Cardiothoracic Centre, University Hospital, Tremona Rd, Southampton, England. a more active part in the function of the valve than was previously thought [10]. In 57 of 64 valves studied with two leaflets, examination of the ventricular aspect revealed evidence of three sinuses and three interleaflet triangles [9], one of the triangles being deficient in height. Also, a tricuspid valve morphology is preferable as it provides a more effective central flow opening for a given ring size than is possible with a bicuspid valve. We describe a technique of valvuloplasty that involves incision of the raphe and suspension of the cusps with bovine pericardium. This renders the valve tricuspid and trisinusoidal, and the deficient interleaflet triangle is recreated, resulting in a greatly increased cross-sectional area of the valve orifice. Patients and Methods Patients Between 1991 and 1996, six children underwent an aortic valvuloplasty using bovine pericardium. The median age of the children was 5.9 years (range, 14 months to 17 years), and the mean weight was 20.0 kg (range, 11.4 to 71 kg). An aortic systolic murmur was detected in all patients during the first week of life. Two patients had a previous aortic valvotomy. One of these had mild aortic valve stenosis at birth (gradient, 20 mm Hg) associated with moderately severe coarctation of the aorta (gradient, 40 mm Hg), multiple ventricular septal defects, and patent ductus arteriosus. He required a subclavian flap repair of the coarctation of the aorta, banding of the pulmonary artery for multiple ventricular septal defects, and ligation of the patent ductus arteriosus in infancy, 1997 by The Society of Thoracic Surgeons /97/$17.00 Published by Elsevier Science Inc PII S (96)

2 466 TOLAN ET AL Ann Thorac Surg AORTIC VALVE REPAIR IN CHILDREN 1997;63:465 9 Fig 1. (A) A view of congenital bicuspid aortic valve showing one larger cusp with a median raphe. (B) Incision of the median raphe. (C) A pericardial triangle (inset) is folded and sutured along both edges of the divided raphe and vertically to the aortic wall to provide support in diastole. and debanding of the pulmonary artery with conventional aortic valvotomy at 16 months. The other patient had critical aortic stenosis associated with severe mitral regurgitation requiring aortic valvotomy at 3 weeks of life. All 6 patients were followed up in the ensuing years using two-dimensional echocardiography with Doppler studies. The gradient across the aortic valve was estimated by measuring peak systolic velocity from Doppler studies, and aortic regurgitation was assessed. Three patients had cardiac catheterization before the aortic valvotomy with bovine pericardium suspension. Indications for operation were transaortic pressure gradients of 80 to 96 mm Hg (mean, 85 mm Hg) in 4 patients, 3 of whom were asymptomatic (2 had previous valvotomy 3.6 and 5.8 years previously); two episodes of syncope in 1 patient whose gradient was 65 mm Hg; and symptoms of breathlessness in 1 patient who had a gradient of 60 mm Hg. There was electrocardiographic evidence of left ventricular strain in 2 patients. Four patients had aortic regurgitation preoperatively. Appearances of the valves suggested bicuspid morphology in all cases. Surgical Technique Moderate hypothermia with core cooling to 25 to 28 C, single or bicaval venous cannulation, and a left ventricular vent were used. Myocardial protection consisted of topical hypothermia and hyperkalemic cardioplegic arrest. If significant aortic regurgitation was present, the cardioplegic solution was directly infused into the coronary ostia after the aortic root was opened. Repeated doses of cardioplegia were given at intervals throughout the operation if required. The ascending aorta was incised and retracted, and the valve area was inspected. In all our patients bicuspid morphology was confirmed (Fig 1A). Any cuspal fusion was incised in a conventional manner. The raphe between the other nonsupported cusp was then incised as far as the aortic wall (Fig 1B). A measurement of the length of this raphe was made, and note was taken of the height of the sinutubular ridge. An isosceles triangle of bovine pericardium was cut with dimensions such that the base was twice the length of the incised raphe and the vertical height was slightly greater than the height of the sinutubular ridge (Fig 1C). The pericardium was folded along its vertical axis and oriented in the aorta such that the two edges of the base were sutured to the two free edges of the incised raphe, and the fold in the pericardium was sutured vertically to the aortic wall to a level above the sinutubular ridge (see Fig 1C). Thus the valve was rendered tricuspid and trisinusoidal, and the deficient interleaflet triangle was recreated, preventing cusp prolapse. One patient initially underwent a commissur-

3 Ann Thorac Surg TOLAN ET AL 1997;63:465 9 AORTIC VALVE REPAIR IN CHILDREN 467 Table 1. Patient Characteristics Variable Patient Number Age at operation (y) Weight at operation (kg) Diagnosis AS/AR AS/AR AS/AR/MR AS AS AS/AR Symptoms Previous aortic operation Follow-up (mo) Echocardiography Gradient (mm Hg) Preop Postop /57 a 30 Current Regurgitation Preop Mild Mild Severe Mild Absent Mod Postop Absent Absent Mild Mild Absent Absent Current Mild/mod Mild Mild Mild/mod Trivial Absent a The first gradient of 80 mm Hg was after an initial conventional commisurotomy; the second gradient of 57 was after the valve was repaired with pericardium. AR aortic regurgitation; AS aortic stenosis; Mod moderate; MR mitral regurgitation. otomy of about 5 mm between the right and noncoronary cusps. There was no fusion between the left and noncoronary cusps. After cardiopulmonary bypass was discontinued, the aortic gradient was still measured at 80 mm Hg. Cardiopulmonary bypass was therefore reinstituted and repair of the valve effected using the technique described with a triangular patch of pericardium. A further patient, aged 17 years, had extensive decalcification of the annulus and thinning of the larger cusp before repair with the calf pericardium. One patient also had an associated mitral valve repair by chordal shortening and annuloplasty. Intraoperative transesophageal echocardiography was used to validate early competence of the repaired valve. Postoperative gradients were determined by Doppler echocardiography. Results Follow-up has ranged from 2 to 60 months (median, 34 months). There was no mortality or morbidity associated with the operation. All operations were of short duration: the maximum cardiopulmonary bypass time was 75 minutes in the patient who had concomitant mitral valve repair. Intraoperative echocardiography demonstrated successful initial repair in all patients, with good coaptation of cusps and no further modification required. Measured gradients were much reduced from preoperative levels (Table 1). All patients were discharged from the hospital within 8 days, and to date at follow-up all 6 remain symptom free. Peak systolic Doppler gradients decreased significantly from mm Hg preoperatively to 26 9 mm Hg postoperatively. Mild aortic regurgitation was described in 4 patients preoperatively and 2 patients immediately postoperatively (see Table 1). Serial planimetric evaluation using the largest area during systole from two-dimensional echocardiography allowed estimation of the effective valvular orifice. This was almost doubled compared with the preoperative values, an increase from 33% 6% of total aortic area preoperatively to 64% 3% postoperatively, thus allowing blood flow to increase 3.76 times that of the preoperative state. Preoperative echocardiographic pictures in diastole (Fig 2A) and systole (Fig 2B) demonstrate the bicuspid valve with the large leaflet inhibiting wide opening of the valve. Postoperatively, the now tricuspid morphology of the valve in diastole can be seen (Fig 3A), and in systole there is a much greater valvular orifice area (Fig 3B). Electrocardiographic evidence of left ventricular strain reverted in the 2 patients in whom it was present preoperatively. Late follow-up echocardiography and Doppler studies showed mobile cusps with the pericardial extension maintaining its flexibility, resulting in a widely patent orifice in systole (see Fig 3A), and a tricuspid configuration in closure in diastole (see Fig 3B). Measurement of gradients demonstrated no increase in stenosis over the period of follow-up. However, there has been some increase in the amount of valve regurgitation over the years postoperatively (see Table 1). Comment Attempts to preserve the aortic valve with congenital stenosis have included thinning of valve leaflets, augmentation of scarred and retracted leaflets with autologous pericardium, incision of the raphe with release of the rudimentary commissure from the aortic wall, and extension of the valvotomy incision into the aortic wall and on both sides of the commissure. Using a combina-

4 468 TOLAN ET AL Ann Thorac Surg AORTIC VALVE REPAIR IN CHILDREN 1997;63:465 9 loses the advantages of the tricuspid morphology. Our technique, by creating a tricuspid valve, achieves almost a doubling of the effective orifice area, which results in an exponential increase in blood flow. It is particularly appropriate when there is very little fusion of the bicuspid valve and therefore no commissurotomy is possible. Incision of the raphe of the fused larger leaflet allows the cusps to fold back onto the aortic wall in systole, thus allowing a much larger central orifice. In diastole they are prevented from prolapsing by the supporting pericardial insert. Our technique also attempts to restore the trisinusoidal morphology of the valve. Leonardo da Vinci first demonstrated the importance of the trisinusoidal configuration and formation of vortices on preventing shear stress on the leaflets during valve closure [12]. Eddy formation behind the leaflets prevents their impaction on the aortic wall on opening, and in diastole, by the outward movement of the aortic walls, the sinuses assume an almost spheric shape and thus allow much of the load on the leaflets to be taken up by the sinus walls. Fig 2. Preoperative echocardiography: (A) the aortic valve in diastole showing the bicuspid morphology and (B) the aortic valve in systole showing a restricted valve orifice. tion of techniques, Ankeney and associates [2] achieved a 92.5% chance of avoiding reoperation for 10 years, but by 15 years the chance fell to 73%. In their series the majority of patients were slightly older, between 11 and 15 years. Van Son and associates [8] reviewed the cases of 22 patients, with a median age of 5.7 years, who underwent aortic valvuloplasty; 5 required aortic valve replacement within the first week and a further 8 had either stenosis with a gradient of 40 to 60 mm Hg or severe regurgitation at a median follow-up of 16 months. A bicuspid morphology was present in 10 of the valvuloplasty failures. Caspi and colleagues [11] described a technique of extended aortic valvuloplasty as the initial approach for management of congenital aortic stenosis. Incision of the fused commissures to the aortic wall and then extension in a circumferential fashion in both directions for 1 to 2 mm gave better relief of obstruction and less residual regurgitation than with standard valvulotomy. The same procedure was applied in children with significant recurrent aortic valve stenosis with good results at short-term follow-up. After use of their technique, however, the valve remains bicuspid and thus Fig 3. Postoperative echocardiography: (A) the aortic valve in diastole showing the tricuspid closure lines of the reconstructed valve and (B) the aortic valve in systole demonstrating the widely patent valve orifice of the reconstructed valve.

5 Ann Thorac Surg TOLAN ET AL 1997;63:465 9 AORTIC VALVE REPAIR IN CHILDREN 469 This stress-sharing decreases the stress and the wear on the leaflets, which is of major import when using unstented pericardium in the aortic position. Pericardium has long been used as a valve substitute and for valve repair [13]. A recent experience of unstented porcine pericardium for valve replacement in the aortic position has been described by David and associates [14], who reported on 123 patients with 6-year survival at 91% and very uncommon valve related complications. Duran and colleagues [15] have reported favorable results for cusp extension using glutaraldehydetreated bovine or autologous pericardium, although follow-up was just 30 months. Likewise, Al-Fagih and associates [16] reported single cusp extension using bovine pericardium with excellent results but only 23 months maximum follow-up. Batista and associates [17] reported the replacement of the aortic valve with a monopatch of bovine pericardium, but again follow-up was short. The natural history of free pericardial patches seems to be one of eventual thickening, fibrosis, and retraction. Under high pressure they may stretch and become aneurysmal. However, calcification eventually occurs in glutaraldehyde-treated bovine tissue. Further follow-up studies will determine the eventual role of pericardium in valve reconstruction. Meanwhile, results justify its continued use, and it has been encouraging that in our series there has been no significant restenosis. The slight increase in the amount of regurgitation in 3 of our patients may be due to some shortening of the pericardial tissue and is being kept under constant review. In conclusion, we have described a technique that allows marked enlargement of a bicuspid valve with resuspension of the divided raphe to avoid prolapse by use of a triangular bovine pericardial patch. Although our series is small and the follow-up is only to 5 years, this technique does provide a method of enlarging a bicuspid valve orifice even when there is no commissural fusion. References 1. Wheller JJ, Hosier DM, Teske DW, Kilman JW. Results of operation for aortic valve stenosis in infants, children, and adolescents. J Thorac Cardiovasc Surg 1988;96: Ankeney JL, Tzeng TS, Liebman J. Surgical therapy for congenital aortic valvular stenosis. J Thorac Cardiovasc Surg 1983;85: Williams WG, Pollock JC, Geiss DM, Trusler GA, Fowler RS. Experience with aortic and mitral valve replacement in children. J Thorac Cardiovasc Surg 1981;81: Elkins RC, Santangelo K, Randolph JD, et al. Pulmonary autograft replacement in children. Ann Surg 1992;216: Gerosa G, McKay R, Davies J, Ross DN. Comparison of the aortic homograft and the pulmonary autograft for aortic valve or root replacement in children. J Thorac Cardiovasc Surg 1991;102: Kouchoukos NT, Davilla-Roman VG, Spray TL, Murphy SF. Replacement of the aortic root with a pulmonary autograft in children and young adults with aortic valve disease. N Engl J Med 1994;330: Van Son JA, Reddy VM, Black MD, Rajasinghe H, Haas GS, Hanley FL. Morphologic determinants favoring surgical aortic valvuloplasty versus pulmonary autograft aortic valve replacement in children. J Thorac Cardiovasc Surg 1996;111: McKay R, Smith A, Anderson RH. Morphology of the ventriculoaortic junction in critical aortic stenosis. J Thorac Cardiovasc Surg 1992;104: Angelini A, Ho SY, Anderson RH, Becker AE. The morphology of the normal aortic valve as compared with the aortic valve having two leaflets. J Thorac Cardiovasc Surg 1989;98: Kunzelman KS, Grande J, David TE, Cochran RP. Aortic root and valve relationships. J Thorac Cardiovasc Surg 1994;107: Caspi J, Ilbawi MN, Roberson DA, Najafi H. Extended aortic valvuloplasty for recurrent valvular stenosis and regurgitation in children. J Thorac Cardiovasc Surg 1994;107: Robicesek F. Leonardo da Vinci and the sinuses of Valsalva. Ann Thorac Surg 1991;52: Duran CMG. Pericardium in valve operations. Ann Thorac Surg 1993;56: David TE, Feindel CM, Bos J, Rakowski H. Aortic valve replacement with stentless porcine aortic valves: a six year experience. J Heart Valve Dis 1992;1: Duran C, Kumar N, Gometz B, Halees ZA. Indications and limitations of aortic valve reconstruction. Ann Thorac Surg 1991;52: Al-Fagih M, Kasab SM, Ashmeg A. Aortic valve repair using bovine pericardium for cusp extension. J Thorac Cardiovasc Surg 1988;96: Batista RJV, Dobrianskij A, Comazzi M, Moreira R, Oliveira PF. Clinical experience with stentless pericardial aortic monopatch for aortic valve replacement. J Thorac Cardiovasc Surg 1987;93:19 26.