Ross procedure with aortic root tailoring for aortic valve replacement in the pediatric population

Ross Procedure With Aortic Root Tailoring for Aortic Valve Replacement in the Pediatric Population Lucian A Durham III, MD, PhD, Susan E. desJardins, MD, Ralph S. Mosca, MD, and Edward L. Bove, MD Section of Thoracic Surgery, Pediatric Cardiovascular Surgery, University of Michigan School of Medicine, Ann Arbor, Michigan

Background. Aortic valve r e p l a c e m e n t with a p u l m o nary autograft (Ross procedure) is b e i n g a p p l i e d more c o m m o n l y in children. A l t h o u g h indications for this procedure have b e e n expanded, the presence of a dilated aortic a n n u l u s has r e m a i n e d a relative contraindication. In this condition, the use of an u n d e r s i z e d autograft in an enlarged aortic a n n u l u s m a y result in significant aortic regurgitation. Methods. A m o n g 68 children and y o u n g adults undergoing the Ross procedure, 15 (age range, 8 to 24 years) with severe aortic regurgitation or stenosis and an aortic a n n u l u s d i a m e t e r that was at least 2 m m larger than the p u l m o n a r y a n n u l u s h a d aortic root tailoring. In this group, the diameter of the aortic a n n u l u s m e a s u r e d 26.6 + 1.3 m m (mean + s t a n d a r d error of the mean), w h e r e a s that of the p u l m o n a r y a n n u l u s was 22 - 0.9 mm. The m e a n a n n u l a r difference was 4.6 --- 0.7 m m (range, 2 to 12 mm). The aortic a n n u l u s was r e d u c e d b y excising a triangular w e d g e of tissue posteriorly from the aortic valve a n n u l u s at the level of the commissure b e t w e e n the left and noncoronary cusps e x t e n d i n g into the anterior

leaflet of the mitral valve. The edges were reapproxim a t e d over a calibrated dilator to a d j u s t the final size of the aortic a n n u l u s to 2 m m smaller than that of the p u l m o n a r y autograft. Circumferential felt strips were not used in any patient. Results. All patients survived and m o r b i d i t y was limited to one reoperation for bleeding. D o p p l e r echocardiographic examination p e r f o r m e d at discharge d e m o n strated that no patient h a d more than trace to 1+ aortic regurgitation and none h a d evidence of aortic stenosis. Over a m e a n follow-up p e r i o d of 6.3 + 1.5 months (range, 1 to 16 months) there has b e e n no late morbidity or mortality and no progression of aortic regurgitation. Conclusions. Aortic root tailoring further extends the use of the Ross procedure to patients w i t h excessive aortic a n n u l a r dilation w h i l e m a i n t a i n i n g the potential for growth, w h i c h is particularly i m p o r t a n t in the pediatric population.

he use of prosthetic devices for aortic valve replacem e n t in infants a n d children is associated with n u m e r o u s s h o r t - t e r m a n d l o n g - t e r m complications and, in most cases, is c o n s i d e r e d to be palliative [1-4]. The initial description of aortic valve r e p l a c e m e n t with a p u l m o n a r y autograft b y Ross [5] in 1967 p r o v i d e d an attractive alternative to these various prostheses. The Ross p r o c e d u r e obviates the n e e d for anticoagulation a n d provides autologous tissue with the potential to maintain growth [6, 7]. The viability of p u l m o n a r y autografts in the aortic position is well established, a n d the Ross proced u r e has r a p i d l y b e c o m e the p r o c e d u r e of choice for aortic valve r e p l a c e m e n t in the y o u n g e r p o p u l a t i o n [8]. A l t h o u g h the indications for p u l m o n a r y autograft rep l a c e m e n t of the aortic valve have b e e n e x p a n d i n g as experience with the p r o c e d u r e has increased, size mis-

match has r e m a i n e d a relative contraindication to the procedure, particularly in the presence of a dilated aortic annulus. W h e n the aortic a n d p u l m o n a r y a n n u l u s d i a m eters are similar in size, no changes in the i m p l a n t a t i o n t e c h n i q u e are required. However, w h e n the aortic a n n u lus d i a m e t e r exceeds that of the p u l m o n a r y valve, significant aortic insufficiency m a y result after the Ross procedure, which m a y c o m p r o m i s e the long-term outcome [9]. The use of circumferential strips of prosthetic material or p u r s e s t r i n g sutures a r o u n d the aortic a n n u l u s to reduce its circumference to a m o r e a p p r o p r i a t e size has b e e n described, b u t these techniques have the potential to limit growth, a d i s a d v a n t a g e in y o u n g patients [10]. In 1965, Barratt-Boyes [11] r e p o r t e d a t e c h n i q u e of r e d u c i n g the size of the aortic a n n u l u s in association with aortic valve r e p l a c e m e n t with an aortic allograft. This procedure u s e d a noncircumferential r e m o v a l of tissue posteriorly at the level of the anterior leaflet of the mitral valve. This a p p r o a c h has the obvious a d v a n t a g e of allowing c o n t i n u e d growth of the a n n u l u s in infants a n d y o u n g children. W e r e p o r t the results of this p r o c e d u r e of aortic

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Presented at the Thirty-third Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Feb 3-5, 1997. Address reprint requests to Dr Bore, Pediatric Cardiovascular Surgery, F7830 Mott Hospital, Box 0223, 1500 E. Medical Center Dr, Ann Arbor, MI 48109. © 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

(Ann Thorac Surg 1997;64:482-6) © 1997 b y The Society of Thoracic Surgeons

0003-4975/97/$17.00 PII S0003-4975(97)00567-5

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Fig 1. The autograft is removed as illustrated and sized over a calibrated dilator ffnset). The broken line represents the level of transection of the aorta.

root tailoring to more closely approximate the diameters of the aortic annulus and pulmonary autograft in association with the Ross procedure.

Patients and M e t h o d s Between January 1991 and July 1996, 68 patients underwent pulmonary autograft replacement of the aortic valve (Ross procedure) for aortic stenosis, regurgitation, or both at C. S. Mott Children's Hospital, University of Michigan Medical School. Aortic root tailoring was begun in March 1995, and since that time 15 patients have undergone this modification of the procedure. This technique was selected when the aortic annulus diameter was 2 mm or greater than that of the pulmonary annulus. The patients" ages ranged from 8 to 24 years (mean, 14.2 _+ 1.5 years). There were 12 male and 3 female patients. All patients underwent complete preoperative transthoracic Doppler echocardiographic evaluation as well as additional intraoperative transesophageal Doppler echocardiography to measure the aortic and pulmonary annular diameters. Operation was performed via median sternotomy with cardiopulmonary bypass at a perfusate temperature of 25°C. Myocardial protection was by means of a combination of cold antegrade and retrograde blood cardioplegia with topical hypothermia. After electromechanical arrest of the heart, the pulmonary artery was transected at its bifurcation and the pulmonary valve annulus size was approximated with calibrated dilators before excision of the autograft. The pulmonary autograft was then harvested with a 2- to 3-turn cuff of muscle, care being taken to avoid injury to the underlying left main coronary artery and the septal perforators posteriorly. The final size of the harvested autograft was again measured with calibrated dilators (Fig 1). This size was taken as the largest dilator that could be passed through the explanted autograft without stretching. The autograft was placed in cold saline solution while awaiting implantation. The aorta was then transected approximately 2 to

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3 mm above the sinotubular ridge, leaving most of the noncoronary sinus of Valsalva tissue with the distal aorta. The diseased aortic valve was excised and the coronary ostia were removed with buttons of aortic tissue (Fig 2). Once the annular difference was measured, tailoring of the root was begun by excising a triangular wedge of tissue from the aortic valve annulus at the level of the commisure between the left and noncoronary cusps extending into the anterior leaflet of the mitral valve (see Fig 2). The V-shaped defect was then reapproximated over a calibrated dilator, which was adjusted to achieve a final diameter 2 mm less than that of the pulmonary annulus. The edges were reapproximated with interrupted, pledgeted, horizontal mattress polypropylene sutures (see Fig 2, inset). The autograft was then sutured to the tailored aortic root with a continuous polypropylene suture beginning below the origin of the left coronary artery. The coronary arteries were then implanted into the facing sinuses of the autograft. The right ventricular outflow tract was then reconstructed with an appropriately sized cryopreserved pulmonary allograft while the patient was being rewarrned. The distal aortic anastomosis was completed last (Fig 3). Intraoperative transesophageal Doppler echocardiographic examination was used in each patient to assess valvular function of both the aortic and pulmonary valves. All patients underwent an additional complete transthoracic Doppler echocardiographic study before discharge from the hospital.

Results Three patients had undergone a prior operation or percutaneous catheter intervention. One patient had previously undergone open surgical valvotomy and 2 others had undergone balloon valvuloplasty as infants. All patients had severe aortic stenosis, aortic regurgitation, or a

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/ Fig 2. The coronary arteries have been excised as buttons in preparation for reimplantation into the autografl. The broken lines show the excision of the aortic annulus to tailor it for acceptance of the pulmonary autograft. The annulus is then sized to a diameter 2 mm smaller than the autografl and the V-shaped area is reapproximated with horizontal mattress sutures ffnset),

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to 1+ aortic regurgitation a n d no more than trace pulm o n a r y insufficiency of the allograft valve. There were no systolic left ventricular outflow tract gradients after tailoring of the a n n u l u s . No change in mitral valve function was n o t e d on postoperative study.

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Comment

\ Fig 3. The pulmonary autograft is sub, red into the aortic position with the coronary arteries reimplanted; the right ventricular outflow tract has been reconstructed with an appropriate pulmonary allograft.

combination preoperatively. The preoperative diameter of the aortic a n n u l u s in these patients was 26.3 + 1.5 m m a n d the p u l m o n a r y a n n u l u s m e a s u r e d 22.0 -+ 1.0 m m in diameter (Table 1). The m e a n a n n u l a r difference was 4.3 _+ 0.7 m m (range, 2 to 12 mm). There was no early or late mortality in this series. Morbidity was limited to one reoperation for postoperative bleeding. Postoperative Doppler echocardiographic assessment of the autograft valve before discharge from the hospital revealed that no patient had more than trace

R e p l a c e m e n t of the aortic valve in i n f a n t s a n d c h i l d r e n is associated with a n u m b e r of p r o b l e m s that seriously limit its effectiveness. The c u r r e n t l y available devices i n c l u d e m e c h a n i c a l , heterograft, a n d allograft prostheses, all of which, however, have significant l i m i t a t i o n s in y o u n g patients. These i n c l u d e size m i s m a t c h , availability, durability, growth limitation, a n d t h r o m b o e m bolic complications, w h i c h often result in m a j o r postoperative m o r b i d i t y in a d d i t i o n to the n e e d for early a n d f r e q u e n t reoperation. In children a n d y o u n g adults who require aortic valve replacement, the Ross procedure has now e m e r g e d as the operation of choice because it overcomes nearly all of these limitations. The p u l m o nary autograft is virtually always available a n d it provides an autologous, viable tissue valve in the aortic position that m a i n t a i n s the potential to grow. Additionally, it provides freedom from most valve-related complications, including thromboembolism, a n d therefore obviates the n e e d for long-term anticoagulation in children [7]. Although the cryopreserved allograft used to replace the p u l m o n a r y valve is unlikely to provide the same degree of durability as the autograft a n d reoperation will be required, this limitation is far less serious than repeated aortic valve replacements. The durability of the autograft valve has b e e n d o c u m e n t e d in the adult patient, b u t long-term studies are not yet available for infants a n d y o u n g e r children [12]. The current preferred technique for the Ross procedure is to insert the valve as a root replacement [13]. This requires close size matching to avoid distortion a n d

Table 1. Patient and Valve Characteristics

Patient No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Valve Dysfunction

Aortic Annulus (ram)

Pulmonary Annulus (ram)

AS/AR AS AR AR AS/AR AS/AR AR AS/AR SAS/AR AR AR AS/AR AS/AR AS/AR AR

23 33 22 35 23 23 22 27 25 30 27 26 25 21 38

19 28 19 26 19 19 20 24 23 23 24 21 23 16 26

AR = aortic regurgitation;

AS = aortic stenosis;

SAS = subaorticstenosis.

Annular Difference (turn) 4 5 3 9 4 4 2 3 2

Postoperative Aortic Regurgitation 1+ Trace 1+ Trace Trace Trace Trace Trace 1+

7

1+

3 5 2 5 12

Trace 1+ 1+ Trace 1+

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DURHAM ET AL ROSS PROCEDURE FOR ANNULAR SIZE MISMATCH

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0.5

0.25-

0!

< -0.25-

-0.5

I $ 0 - 1+

>_ 2 +

Aortic Regurgitation Fig 4. Aortic regurgitation as a function of the difference of the aortic annulus diameter (AV) and pulmonary annulus diameter (PV). Significant aortic regurgitation was seen only in those patients where the annular difference was 2 mm or greater.

postoperative regurgitation. W h e n the aortic a n n u l u s is smaller than that of the p u l m o n a r y annulus, particularly in association with subaortic stenosis, division of the a n n u l u s a n d s e p t u m to enlarge the outflow tract has b e e n shown to be a useful addition to the Ross procedure. A l t h o u g h this situation is m o r e c o m m o n in children, l o n g - s t a n d i n g aortic regurgitation, particularly after prior intervention on the valve, m a y result in excessive dilatation of the aortic a n n u l u s b e y o n d that of the p u l m o n a r y valve. Use of an u n d e r s i z e d autograft in an e n l a r g e d a n n u l u s has b e e n shown to result in aortic regurgitation after the Ross p r o c e d u r e [9]. In the past, this condition was c o n s i d e r e d a relative contraindication to the Ross p r o c e d u r e [14]. To avoid this p r o b l e m , however, techniques have b e e n d e s c r i b e d to r e d u c e the size of the aortic a n n u l u s by insertion of a circumferential felt strip or p l a c e m e n t of a p u r s e s t r i n g suture a r o u n d the autograft [10]. T h e s e t e c h n i q u e s a r e effective in a d u l t p a t i e n t s b u t h a v e the p o t e n t i a l to limit the g r o w t h of the a n n u l u s and, c o n s e q u e n t l y , are less o p t i m a l for use in y o u n g children. This p r o b l e m was a d d r e s s e d b y Barratt-Boyes in association with aortic valve r e p l a c e m e n t with an aortic allograft [15]. A noncircumferential technique of reducing the aortic a n n u l u s b y excision of a V-shaped w e d g e of tissue posteriorly at the level of the anterior leaflet of the mitral valve was shown to be effective in optimizing the size discrepancy b e t w e e n the aortic a n n u l u s a n d the allograft without resulting in mitral valve dysfunction. W e b e g a n to e m p l o y this t e c h n i q u e after an examination of our earlier results with the Ross p r o c e d u r e d e m o n strated significantly m o r e postoperative aortic regurgitation in those patients in w h o m the aortic valve d i a m e t e r was at least 2 m m larger than that of the p u l m o n a r y a n n u l u s [161 (Fig 4). Furthermore, that analysis d e m o n -

485

strated that the m o s t o p t i m a l p o s t o p e r a t i v e results were achieved in that group of patients w h e r e the difference b e t w e e n the aortic a n n u l u s a n d the p u l m o n a r y a n n u l u s was - 2 . 3 ram. Therefore, b a s e d on these data, we adj u s t e d the native aortic a n n u l u s to a final d i a m e t e r that was a p p r o x i m a t e l y 2 m m smaller than that of the autograft to reduce the risk of autograft dilatation a n d prolapse. This technique has resulted in excellent postoperative valve function. No patient has m o r e than trace to mild regurgitation a n d none has residual left ventricular outflow tract obstruction. Furthermore, there have b e e n no instances of mitral valve stenosis or regurgitation. This reflects relatively s h o r t - t e r m follow-up a n d will r e q u i r e further long-term surveillance. This technique, which is simple a n d reproducible, a p p e a r s suitable for all patients with the possible exception of those with significant calcification in the annulus. Even the extremely dilated aortic a n n u l u s is suitable, a n d this t e c h n i q u e has b e e n successfully u s e d for size discrepancies as large as 12 m m in this series. In s u m m a r y , the Ross p r o c e d u r e has b e c o m e the optimal p r o c e d u r e for aortic valve r e p l a c e m e n t in infants a n d y o u n g children. The p u l m o n a r y autograft provides optimal h e m o d y n a m i c s a n d has the a d v a n t a g e of placing a viable tissue valve in the systemic circulation while a v o i d i n g most v a l v e - r e l a t e d c o m p l i c a t i o n s i n c l u d i n g those associated with l o n g - t e r m anticoagulation. Although m i s m a t c h b e t w e e n the d i a m e t e r of the aortic a n d p u l m o n a r y a n n u l u s has b e e n c o n s i d e r e d a relative contraindication to the Ross p r o c e d u r e in the past, our results d e m o n s t r a t e that the aortic root m a y be tailored to a c c o m m o d a t e a smaller p u l m o n a r y autograft using a t e c h n i q u e that maintains the potential for growth so essential in pediatric patients.

References 1. Rao PS, Solymar L, Mardini MK, Fawzy ME, Guinn G. Anticoagulant therapy in children with prosthetic valves. Ann Thorac Surg 1989;47:589-92. 2. Sade RM, Crawford FA, Fyfe DA, Stroud MR. Valve prosthesis in children: a reassessment of anticoagulation. J Thorac Cardiovasc Surg 1988;95:553-61. 3. Schneck MH, Vaughn WK, Reul GJ, O'Laughlin MP. Long term follow-up in children and adolescents with left-sided artificial valves. J Am Coll Cardiol 1993;21(Suppl A):81A. 4. Williams MA. Tissue valves in young patients--a recipe for disaster. J Card Surg 1991;6:620-3. 5. Ross DN. Replacement of aortic and mitral valves with a pulmonary autograft. Lancet 1967;2:956-8. 6. Ross DN, Jackson M, Davies J. The pulmonary autograft--a permanent aortic valve. Eur J Cardiothorac Surg 1992;6: 113-7. 7. Elkins RC, Knott-Craig CJ, Ward KE, McCue C, Lane MM. Pulmonary autograft in children: realized growth potential. Ann Thorac Surg 1994;57:1387-94. 8. Elkins RC, Santangelo KL, Seltzer P, Randolph JD, KnottCraig CJ. Pulmonary autograft replacement of the aortic valve: an evolution of technique. J Card Surg 1992;7:108-16. 9. David TE, Omran A, Webb G, Rakowski H, Armstrong S, Sun Z. Geometric mismatch of the aortic and pulmonary roots causes aortic insufficiency after the Ross procedure. J Thorac Cardiovasc Surg 1996;112:1231-9. 10. Cohn LH. Prosthetic aortic valves. Semin Thorac Cardiovasc Surg 1996;8:231-75.

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11. Barratt-Boyes BG. A method for preparing and inserting a homograft aortic valve. Br J Surg 1965;52:847-56. 12. Matsuki O, Okita Y, Almeida RS, et al. Two decades' experience with aortic valve replacement with pulmonary autograft. J Thorac Cardiovasc Surg 1988;95:705-11. 13. O'Brien MF. Allograft aortic root replacement: standardization and simplification of technique. Ann Thorac Surg 1995; 60:$92-4.

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14. Elkins RC. Pulmonary autograft: expanding Indications and increasing utilizations. J Heart Valve Dis 1994;3:356--7. 15. Elkins RC. Congenital aortic valve disease: evolving management. Ann Thorac Surg 1995;59:269-74. 16. Ludomirsky O, Ludomirsky A, Lloyd T, et al. Echocardiographic predictors for successful aortic valve replacement with pulmonary autograft (Ross) procedure in children. Abstract: American Society of Echocardiography, 1995.

DISCUSSION DR RONALD C. ELKINS (Oklahoma City, OK): I compliment Dr Durham and associates on a really outstanding series of patients and a very nice presentation of a means of modifying the aortic annulus so that it is appropriate for the pulmonary annulus. In sizing the pulmonary annulus, as it is a structure that has minimal or no connective tissue and clearly is readily dilated, how do you decide with your calibrated dilator that you are not stretching or distorting the annulus at the time you do it? The second comment I would make is one of caution. The area of dilatation that occurs in those patients in w h o m late aortic insufficiency develops is in that portion of the annulus that you have not fixed. You have changed the size at that point in time, but it is connective tissue that has the same propensity to dilate as it has in the past. We have had a n u m b e r of patients who have been perfectly well at 16 months, some have been perfectly well at 6 years with essentially no aortic insufficiency, and then aortic insufficiency begins to develop. And the cause of the insufficiency was aortic annular dilatation after the Ross procedure. I think that patients who have an adult-size aortic annulus or somebody who has a 24-mm aortic annulus at the time you complete the operation or a 22-mm aortic annulus probably should have his or her aortic annulus "fixed" at that size at the

time the Ross procedure is done. And I feel very firm in that recommendation. I enjoyed the paper very much. Certainly there are several options as to how to tailor the aortic annulus that have been presented over the last 2 or 3 years because those people working in the field have identified this as one of the areas of concern in the operation, and I think we will know more as you begin to present further follow-up on this. DR DURHAM: Thanks, Dr Elkins. In regard to how we size the autograft, in addition to preoperative TEE measurements, what we have done is again pretty much eyeball it. We take a calibrated Hegar dilator and place it through the valve and look at a size that essentially slides easily without feeling like we have to pull it down over the dilator. It is certainly less than an exact science. Regarding reduction of the annular diameter, we have looked at this as not so much the only way to do it, but as another method. There is certainly a multitude of ways to reduce the annulus that have been described, not any of which could be pointed to as incorrect. And, again, our follow-up is only a mean of 61/2 months, so we have not seen any annular dilatation, and we have not seen the onset of any late aortic regurgitation in these patients. But only time will tell as we continue to follow up these patients.