Special Report
The Ross procedure: suitable for everyone? Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
Expert Rev. Cardiovasc. Ther. 12(5), 549–556 (2014)
Alexander Weymann*1,2, Anton Sabashnikov2 and Aron-Frederik Popov2 1 Department of Cardiac Surgery, Heart and Marfan Center – University of Heidelberg, INF 110, 69120 Heidelberg, Germany 2 Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Hill End Road, Harefield, Middlesex, UB9 6JH, London, UK *Author for correspondence: Tel.: +49 622 1563 6511 Fax: +49 622 156 5585 [email protected]
informahealthcare.com
In 1967, Donald Ross transferred the patient’s own pulmonary valve into the aortic root. Although results of this technique were encouraging, the Ross procedure did not gain widespread popularity until the late 1980s when surgeons started to implant the pulmonary autograft as a freestanding full root replacement with reimplantation of the coronary arteries. However, frequent dilatation of the pulmonary autograft was observed using the freestanding full root replacement technique. In contrast, the original subcoronary implantation technique and aortic root inclusion technique prevented dilatation in the long-term. Through advancing know-how in aortic root surgery and confidence, the Ross procedure has also been used in combined procedures and complex clinical presentations with good long-term results, which encourage continual use. However, the Ross procedure is a complex operation; careful patient selection and experience of the surgeon are mandatory requirements to achieve satisfactory results. KEYWORDS: aortic valve replacement • homograft • neoaortic regurgitation • pulmonary autograft • root replacement technique • Ross procedure • subcoronary implantation technique
Nowadays, the aortic valve prosthesis is well developed and has been altered and adjusted to deliver major function, minimal complication and maximal strength [1–7]. Even though major gains have been accomplished, there still are numerous prosthesis-related problems to be dealt with [8,9]. Given these circumstances, a number of research groups have been working to improve the aortic valve prosthesis since optimal aortic valve replacement prosthesis does not exist yet [9–11]. Patients with mechanical prostheses are exposed to permanent anticoagulation, restricted hemodynamics and a higher risk for thromboembolism and endocarditis [8,12–14]. In contrast, the biological valve shows a better hemodynamic functioning than mechanical replacement valves and does not need enduring anticoagulation therapy [8]. One of the biggest weaknesses is structural deterioration, which could lead to dysfunction and new intervention [15]. The latter concern represents the key for not implanting a biological valve in younger patients. Aortic valve replacement with the pulmonary autograft shows good long-term functional results even in combined procedures and complex clinical presentations, which encourage continual use [9,16–19]. No other category of
10.1586/14779072.2014.909285
aortic valve replacement shows better longterm, event-free survival outcomes [9,16,17,20]. With an advancement of knowledge and confidence, the pulmonary autograft has also been used in surgery for infection of the aortic root because of native and prosthetic valve endocarditis [21]. Experience proposes a higher conformability and resistance of the vital tissue to infection [21]. In spite of the difficulty of the operation in patients with an elevated risk of bleeding, the result has been adequate [21]. However, it must be made very clear that the pulmonary autograft is not immune to endocarditis [21]. Presently, the general hospital mortality for aortic valve replacement with a mechanical or bioprosthetic device is 2.1% [22]. In young adults, the number of hospital mortality is insignificant. According to experienced surgeons, the risks of pulmonary autograft procedure are comparable [16,23,24]. However, most surgeons have no intention of taking additional mortality throughout the learning curve and causing pulmonary valve disease. Moreover, concerns were expressed whether the pulmonary valve withstands the hemodynamic stress of the aortic position [25]. Established in 2002, the German-Dutch Ross Registry assesses long-term results that
Ó 2014 Informa UK Ltd
ISSN 1477-9072
549
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
Special Report
Weymann, Sabashnikov & Popov
Figure 1. A schematic drawing of pulmonary root harvesting technique. Care should be taken not to harm the left anterior descending coronary artery or its first septal branch.
include data from 12 departments of cardiac surgery since 1988 [26–30]. Until today, increasing numbers of patients have profited from this operation; nonetheless, only a few surgeons have performed it [26–30]. Historic evolution of the Ross procedure
Ross described pulmonary autograft replacement of the aortic valve in patients in 1967 – a pioneering advance that preceded
the era of cardioplegic arrest [31]. The pulmonary valve was excised and implanted in the receiving patient’s aortic root, leaving the coronary ostia complete in their original condition in the aortic root [31]. The biological issues of homograft degeneration are transferred to the low-pressure pulmonary position. Here, optimal valve function plays a lesser role and failure arises gradually [25]. In 1991, Ross presented his findings of the subcoronary implantation technique for the first time [32]. Follow-up studies of 339 patients up to 24 years showed 80% survival rate and 85% freedom from reoperation. Ten years after that first report, more current findings of the first patient group that comprised 131 patients with a mean follow-up of 20 years reported that freedom from reoperation was 76% at 10 years and 62% at 20 years [33] and freedom from autograft replacement was 88% at 10 years and 75% at 20 years. Severe regurgitation of neoaortic valve proved to be the main indication for reoperation in 28 of 30 patients. Freedom from pulmonary homograft replacement was 69% at 25 years [33]. But this technically challenging subcoronary implantation did not achieve extensive attention. Nevertheless, at the end of the 1980s, the Ross procedure experienced a revival when the knowledge of surgeons applying coronary buttons for aortic root operations promoted pulmonary autograft replacement using the full-root technique [34]. This was further facilitated by the publication of excellent midterm results in the 1990s [35]. In the modality of the Ross procedure described here, the complete pulmonary root is implanted into the aortic position after the aortic root is removed, including the re-implantation of the coronary arteries buttons into the neoaortic root. Since this technique is relatively simple to perform in comparison to the subcoronary implantation and consequentially shows more predictable early results, it is widely accepted among cardiac surgeons [35]. Today, most surgeons perform the root replacement technique, whereas the use of the initial subcoronary implantation technique is rarely applied. Surgical technique
Figure 2. A completed Ross procedure with a homograft replacement of the right ventricular outflow tract.
550
A number of reasons are responsible for the initial nonacceptance of the Ross operation. Due to its complexity, the surgeon is obliged to perform an extensive double valve operation. In contrast, a biological or mechanical prosthesis could be inserted in only a third of the operation time. During the learning curve, early morbidity and mortality were considerable [36]. This is no longer the case due to enhanced surgical methods. This operation is suitable for most patients with aortic disease also in the setting of a bicuspid aortic valve and offers a longlasting nonantigenic valve with freedom from thromboembolism or degenerative changes [26–29]. The pulmonary root is excised without harming the left anterior descending coronary artery and its first septal branch, which are in close proximity of the posterior aspect of the valve (FIGURE 1). An aortic or pulmonary homograft replaces the pulmonary valve and artery (FIGURE 2). Subsequently, the pulmonary Expert Rev. Cardiovasc. Ther. 12(5), (2014)
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
The Ross procedure
valve replaces the diseased aortic valve by either full-root replacement [37] or the original subcoronary implantation technique (FIGURES 3 & 4). The left pulmonary sinus should be located in the position of the right coronary sinus, the anterior pulmonary sinus should replace the noncoronary sinus and the right pulmonary sinus should be situated in the former left coronary sinus [38]. Since the pulmonary root is rather thin, there is a risk of bleeding. Alterations to the original technique have focused on that difficulty. For example, the Elkins group in Oklahoma [39] and consequently others [40] applied a ‘root inclusion’ method to insert the pulmonary cylinder where the pulmonary root is implanted within the native aorta while the circumference of the pulmonary outflow is preserved (FIGURE 5). Holes made in the pulmonary arterial wall serve to accommodate the native coronary ostia. This alteration avoids distortion of the commissures, offers external support for the distensible annulus and reduces bleeding [39,40]. Evidently, the Ross procedure commands time, judgment and expertise. Increasing usage has been motivated by enhanced myocardial protection techniques as well as free availability of homograft valves. Currently, it finds application in patients till the age of 60 years, in individual cases up to the age of 70 years, but should be reserved to experienced centers and surgeons [9]. Hemodynamic performance & outcome
In case of imperfect implantation or autograft patient mismatch with a large annulus, early reoperation for aortic regurgitation is the result. Transvalvular gradients are negligible at rest and under conditions of enhanced cardiac output as well as evidently more suited than for any other prosthesis type [41,42]. With the root replacement and in the event of the autograft being implanted as a cylinder, the occurrence of autograft incompetence is almost absent [39,40]. Elkins was mindful of the Ross procedure being contraindicated when the aortic annulus is >27 mm in diameter and spoke out against a mismatch between the autograft and the aortic annulus [39]. In spite of diameter differences, Ross contemplated the pulmonary autograft being applied for aortic root or intra-aortic implantation [43]. Due to the high degree of distensibility of the native, untreated pulmonary arterial wall, the elasticity balances. Since thromboembolism is not the case with the pulmonary autograft, anticoagulation is obsolete in any phase of the treatment [9,26–29]. Brancaccio et al. [18] reported low rates of autograft failure and recommended the Ross procedure as an attractive option for the management of aortic valve disease and complex left ventricular outflow tract obstruction in the pediatric population. Also, it has been proven that the autograft grows in children [44]. Elkins has documented continual size growth of the pulmonary autograft in children, which is proportional to the somatic growth and not likely to be affected by the propensity to stretch [44]. Conclusively, enlargement does not lead per se to significant regurgitation because pulmonary autografts informahealthcare.com
Special Report
Figure 3. The classic approach: implantation of the pulmonary autograft using the free-hand subcoronary implantation technique.
with mild regurgitation postoperatively might become entirely competent in the course of somatic growth [44]. Aortic and pulmonary homografts in the right ventricular outflow tract (RVOT) show long-lasting durability [26–29]. Whereas calcification in right-sided homografts is mainly restricted to the graft wall, the valve itself shows an exceptionally low occurrence of calcification and degeneration. Others demonstrated the fate of aortic homografts utilized for right ventricular outflow reconstruction after pulmonary autograft procedures [45]. The occurrence of homograft wall calcification
Figure 4. A detailed presentation of the subcoronary suturing technique.
551
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
Special Report
Weymann, Sabashnikov & Popov
Figure 5. Pulmonary autograft implantation as root inclusion.
was only 27% in comparison to patients with right-sided homografts in cyanotic congenital heart disease, where the occurrence was 92% [39]. This is partially because of both the young age of the patients with congenital disease and the incidence of pulmonary hypertension [45]. Hechadi et al. [46] chose an alternative approach to reconstruct the RVOT and applied stentless xenografts. In their study, calcific degeneration was observed in both the pulmonary homografts and the stentless xenografts. Interestingly, calcification progressed more rapidly in the stentless xenograft group than in the pulmonary homograft group. Nevertheless, calcifications affected mainly the wall so that both approaches demonstrated similar and satisfactory hemodynamic outcomes at midto long-term follow-up. They concluded that stentless xenografts can be considered as an acceptable alternative for RVOT reconstruction when pulmonary homografts are not available. Dohmen et al. [47,48] used tissue-engineered heart valves for reconstruction of the RVOT during the Ross operation. They achieved excellent hemodynamic performance during mid- and long-term follow-up. Their concept of decellularization of heart valves and seeding with autologous vascular endothelial cells prevented tissue degeneration and improved valve durability. Fate of the pulmonary autograft
Apparently, the main concern about why the pulmonary autograft is not widely accepted as a substitute valve for aortic valve replacement is based on valve insufficiency, which – after the first 10 years – may occur in more than one-third of the patients [49,50]. 552
Sievers et al. discussed 500 Ross procedures, applying the subcoronary technique, and projected for the long term a lower reoperation rate for aortic regurgitation than for the full-root replacement [16]. De Kerchove et al. concluded that the 10-year rate for both survival and freedom from reoperation was identical for the two techniques [51]. They reported autograft dilation and aortic valve prolapse as the major sources for failure in the full-root and inclusion groups, respectively [16,51]. Consistent with the findings of Elkins et al., autograft dysfunction in the first 6 months is a rather exceptional occurrence [52]. At a midterm follow-up of 2.47 years, echocardiographic assessments of the pulmonary autograft showed a minor aortic insufficiency (graded 1/4) in 39.2 –53.6% of patients [53]. A total amount of 3% of patients showed reasonable insufficiency soon after surgery, accumulating to 14.3% at 5 years. In the long run [54], 86 ± 2% of patients were free from pulmonary autograft failure at 10 years, and 74 ± 5% at 16 years. The numbers for children and young adults were similar. The predictors for late valve dysfunction were female gender, age and dilated aortic valve annulus [54]. Furthermore, David et al. [55] stated that the Ross operation offered inferior outcomes in male patients with aortic insufficiency. In their sequence of more than 200 patients, females with aortic stenosis showed the best results [55]. According to Stewart et al., annuloplasty for dilated aortic annulus during Ross procedure cannot avoid neoaortic regurgitation in children [56]. In comparison, excellent long-term outcomes of the Ross and Ross–Konno operation for infants and children with multilevel left ventricular outflow tract stenosis were observed [57,58]. The autografts were free from stenosis, and the occurrence of regurgitation was small with appropriate enlargement of the annulus similar to the somatic growth [57–60]. Prophylaxis of pulmonary autograft failure
Often, pulmonary autografts become increasingly dilated, which appears to be inevitable [49,50]. Both dilation of the sinotubular junction and aortic annulus can lead to aortic insufficiency. Brown et al. outlined a preventive method of dilation for both sides where a tubular Dacron graft replaces the ascending aorta, and external fixation of the aortic annulus is added with a Dacron strip (FIGURE 6). Moreover, they stress the importance of an aggressive treatment of postoperative systemic hypertension [61,62]. In order to support the distensible root, Pacifico et al. [63] applied a circumferential wrap of bovine pericardium. Ungerleider et al. [64] entirely enclosed the autograft in a suitably sized Dacron graft before implantation to prevent autograft dilation. Using a comparable method, other surgeons applied Goretex [65] or a Valsalva graft [66] for equal purpose. David et al. [67] introduced dilatation of the pulmonary autograft as outcome of a mismatch between the diameters of the annulus and the sinotubular junction of the aortic and pulmonary roots. In fact, referring to this divergence in diameter, per-surgical adjustments at the annulus and sinotubular junction did not turn out to prevent late dilatation of the homograft [67]. Expert Rev. Cardiovasc. Ther. 12(5), (2014)
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The Ross procedure
Special Report
In comparison to the study of David et al. [67], Lansac took one further step by integrating the notion of compliant sinuses as most imperative support of aortic root hemodynamics in his examinations of the Ross procedure [68]. At the level of the commissures and sinotubular junction, the dynamic differences observed between the pulmonary and the aortic roots were regarded as a possible predicting factor for subsequent dilatation. These could serve as an explanation for global pulmonary root dilatation when exposed to systemic pressure. Indeed, the conclusion could be drawn that these results of Lansac et al. emphasize the significance of a supra-aortic ridge for appropriate valve competency as well as the necessity for surgical techniques developed to support this region of the autograft. Strategies for autograft failure
Mechanical or bioprosthetic valves have been applied to replace failed pulmonary autografts with or without aortic root replacement [69]. Nevertheless, current progress in valve-sparing aortic root replacement has promoted the implementation of this technique to treat pulmonary autograft insufficiency mainly in the case of failed full-root implantation technique. Luciani et al. applied the Yacoub method for valve-sparing aortic root surgery to address failed pulmonary autografts and named it the Ross–Yacoub procedure [70]. Kerchove et al. repaired dilated autografts using valve-sparing root replacement or ascending aorta replacement. Moreover, they also applied in their series aortic repair techniques on the failed pulmonary autografts like commissural resuspension, free margin plication or resuspension with polytetrafluoroethylene [71]. Expert commentary
In summary, the pulmonary autograft demonstrates low rates of degeneration, endocarditis and thromboembolism for a period >20 years compared with current biological or mechanical replacement valves. Main complications of the procedure are calcific degeneration of the homograft in the RVOT position and pulmonary autograft regurgitation, which is mainly technical in nature. The most reasonable candidates for the Ross procedure are women of childbearing age with aortic stenosis as well as adults with an active lifestyle and a life expectancy of over 20 years. Moreover, infants and small children with left ventricular outflow tract stenosis benefit clearly from a Ross–Konno procedure. A technique to avoid aortic annular dilation should be applied from the very beginning during autograft implantation to warrant excellent long-term results. In our opinion, the Ross procedure is best suited to centers where the expertise exists in daily management. For this reason, regionalization is appropriate to ensure that adequate volumes are present at each specialized center. Given the complexity of the operation, special training is mandatory. Five-year view
Without doubt, the Ross procedure provides excellent results in terms of hemodynamic flow characteristics, autograft function, including potential for growth, patient survival and low informahealthcare.com
Figure 6. An intraoperative image depicting external fixation of the neoaortic root with a Dacron strip to avoid dilatation.
incidence of embolic complications. In the next 5 years, more follow-up studies with larger patient numbers will be available for final judgment of this technique. In future, reinterventions on the right ventricular outflow will be an excellent target for percutaneous [72] and tissue-engineered pulmonary valve replacement [9,47,48]. Moreover, reoperations on the autograft may be increasingly required in the long term (>20 years), but due to advances in valve-sparing techniques, preservation of the living autograft will be possible in experienced hands. Furthermore, the future will show whether improvements in aortic valve repair and developments in valve technology may offer a better alternative to the Ross procedure. Acknowledgements
The authors would like to thank Mrs. Kreutzer for the preparation of the schematic drawings. Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript. 553
Special Report
Weymann, Sabashnikov & Popov
Key issues • Autograft regurgitation remains the crucial weak point of the Ross procedure. • The long-term success of external support techniques to prevent autograft regurgitation in adults is unknown. • Alternative techniques for right ventricular outflow tract reconstruction must be taken into consideration, such as implantation of tissueengineered valves, to improve long-term results. • It is to be expected that future bioprosthetic valves will demonstrate improved long-term results in the aortic position so that the Ross
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procedure may lose its important position in aortic valve surgery.
References
10.
Weymann A, Schmack B, Okada T, et al. Reendothelialization of human heart valve neoscaffolds using umbilical cord-derived endothelial cells. Circ J 2013;77(1):207-16
20.
Brown JW, Patel PM, Rodefeld MD, Turrentine MW. The Ross operation in adolescents. World J Pediatr Congenit Heart Surg 2013;4(4):403-11
11.
Honge JL, Funder J, Hansen E, et al. Recellularization of aortic valves in pigs. Eur J Cardiothorac Surg 2011;39(6):829-34
21.
12.
Massel DR, Little SH. Antiplatelet and anticoagulation for patients with prosthetic heart valves. Cochrane Database Syst Rev 2013;7:CD003464
Schmidtke C, Dahmen G, Sievers HH. Subcoronary Ross procedure in patients with active endocarditis. Ann Thorac Surg 2007;83(1):36-9
••
Single-center study which confirms excellent outcomes of the Ross procedure in active endocarditis.
22.
Hamm CW, Mollmann H, Holzhey D, et al. The German Aortic Valve Registry (GARY): in-hospital outcome. Eur Heart J 2013. [Epub ahead to print]
23.
Andreas M, Wiedemann D, Seebacher G, et al. The Ross procedure offers excellent survival compared with mechanical aortic valve replacement in a real-world setting. Eur J Cardiothorac Surg 2014. [Epub ahead to print]
Papers of special note have been highlighted as: • of interest •• of considerable interest 1.
2.
Une D, Ruel M, David TE. Twenty-year durability of the aortic Hancock II bioprosthesis in young patients: is it durable enough? Eur J Cardiothorac Surg 2014. [Epub ahead of print] McClure RS, McGurk S, Cevasco M, et al. Late outcomes comparison of nonelderly patients with stented bioprosthetic and mechanical valves in the aortic position: a propensity-matched analysis. J Thorac Cardiovasc Surg 2014. [Epub ahead of print]
13.
Halbritter K, Beyer-Westendorf J, Nowotny J, et al. Hospitalization for vitamin-K-antagonist-related bleeding: treatment patterns and outcome. J Thromb Haemost 2013;11(4):651-9
3.
Bouhout I, Stevens LM, Mazine A, et al. Long-term outcomes after elective isolated mechanical aortic valve replacement in young adults. J Thorac Cardiovasc Surg 2013. [Epub ahead of print]
14.
Gabbieri D, Dohmen PM, Linneweber J, et al. Early outcome after surgery for active native and prosthetic aortic valve endocarditis. J Heart Valve Dis 2008;17(5): 508-24; discussion 525
4.
Celiento M, Filaferro L, Milano AD, et al. Single center experience with the Sorin Bicarbon prosthesis: a 17-year clinical follow-up. J Thorac Cardiovasc Surg 2013. [Epub ahead of print]
15.
24.
5.
Bouchard D, Mazine A, Stevens LM, et al. Twenty-year experience with the carbomedics mechanical valve prosthesis. Ann Thorac Surg 2013;97(3):816-23
Maciejewski M, Piestrzeniewicz K, Bielecka-Dabrowa A, Walczak A. Biological artificial valve dysfunction - single-centre, observational echocardiographic study in patients operated on before age 65 years. Arch Med Sci 2011;7(6):993-9
El-Hamamsy I, Eryigit Z, Stevens LM, et al. Long-term outcomes after autograft versus homograft aortic root replacement in adults with aortic valve disease: a randomised controlled trial. Lancet 2010; 376(9740):524-31
16.
Sievers HH, Stierle U, Charitos EI, et al. Fourteen years’ experience with 501 subcoronary Ross procedures: surgical details and results. J Thorac Cardiovasc Surg 2010; 140(4):816-22.822 e811-815
25.
••
One of the largest reports on subcoronary Ross procedure, which deserves the ‘standard status’ against all other reported series on this technique.
Brown JW, Ruzmetov M, Fukui T, et al. Fate of the autograft and homograft following Ross aortic valve replacement: reoperative frequency, outcome, and management. J Heart Valve Dis 2006;15(2): 253-9; discussion 259-260
26.
Charitos EI, Hanke T, Stierle U, et al. Autograft reinforcement to preserve autograft function after the Ross procedure: a report from the German-Dutch Ross registry. Circulation 2009;120(Suppl 11): S146-54
6.
Sansone F, Dato GM, Zingarelli E, et al. Long-term follow-up of stentless prosthesis. J Cardiol 2013. [Epub ahead of print]
7.
Chan V, Kulik A, Tran A, et al. Long-term clinical and hemodynamic performance of the Hancock II versus the Perimount aortic bioprostheses. Circulation 2010; 122(Suppl 11):S10-16
8.
9.
Ruel M, Chan V, Bedard P, et al. Very long-term survival implications of heart valve replacement with tissue versus mechanical prostheses in adults
The Ross procedure: suitable for everyone? Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
Expert Rev. Cardiovasc. Ther. 12(5), 549–556 (2014)
Alexander Weymann*1,2, Anton Sabashnikov2 and Aron-Frederik Popov2 1 Department of Cardiac Surgery, Heart and Marfan Center – University of Heidelberg, INF 110, 69120 Heidelberg, Germany 2 Department of Cardiothoracic Transplantation and Mechanical Circulatory Support, Royal Brompton and Harefield NHS Foundation Trust, Hill End Road, Harefield, Middlesex, UB9 6JH, London, UK *Author for correspondence: Tel.: +49 622 1563 6511 Fax: +49 622 156 5585 [email protected]
informahealthcare.com
In 1967, Donald Ross transferred the patient’s own pulmonary valve into the aortic root. Although results of this technique were encouraging, the Ross procedure did not gain widespread popularity until the late 1980s when surgeons started to implant the pulmonary autograft as a freestanding full root replacement with reimplantation of the coronary arteries. However, frequent dilatation of the pulmonary autograft was observed using the freestanding full root replacement technique. In contrast, the original subcoronary implantation technique and aortic root inclusion technique prevented dilatation in the long-term. Through advancing know-how in aortic root surgery and confidence, the Ross procedure has also been used in combined procedures and complex clinical presentations with good long-term results, which encourage continual use. However, the Ross procedure is a complex operation; careful patient selection and experience of the surgeon are mandatory requirements to achieve satisfactory results. KEYWORDS: aortic valve replacement • homograft • neoaortic regurgitation • pulmonary autograft • root replacement technique • Ross procedure • subcoronary implantation technique
Nowadays, the aortic valve prosthesis is well developed and has been altered and adjusted to deliver major function, minimal complication and maximal strength [1–7]. Even though major gains have been accomplished, there still are numerous prosthesis-related problems to be dealt with [8,9]. Given these circumstances, a number of research groups have been working to improve the aortic valve prosthesis since optimal aortic valve replacement prosthesis does not exist yet [9–11]. Patients with mechanical prostheses are exposed to permanent anticoagulation, restricted hemodynamics and a higher risk for thromboembolism and endocarditis [8,12–14]. In contrast, the biological valve shows a better hemodynamic functioning than mechanical replacement valves and does not need enduring anticoagulation therapy [8]. One of the biggest weaknesses is structural deterioration, which could lead to dysfunction and new intervention [15]. The latter concern represents the key for not implanting a biological valve in younger patients. Aortic valve replacement with the pulmonary autograft shows good long-term functional results even in combined procedures and complex clinical presentations, which encourage continual use [9,16–19]. No other category of
10.1586/14779072.2014.909285
aortic valve replacement shows better longterm, event-free survival outcomes [9,16,17,20]. With an advancement of knowledge and confidence, the pulmonary autograft has also been used in surgery for infection of the aortic root because of native and prosthetic valve endocarditis [21]. Experience proposes a higher conformability and resistance of the vital tissue to infection [21]. In spite of the difficulty of the operation in patients with an elevated risk of bleeding, the result has been adequate [21]. However, it must be made very clear that the pulmonary autograft is not immune to endocarditis [21]. Presently, the general hospital mortality for aortic valve replacement with a mechanical or bioprosthetic device is 2.1% [22]. In young adults, the number of hospital mortality is insignificant. According to experienced surgeons, the risks of pulmonary autograft procedure are comparable [16,23,24]. However, most surgeons have no intention of taking additional mortality throughout the learning curve and causing pulmonary valve disease. Moreover, concerns were expressed whether the pulmonary valve withstands the hemodynamic stress of the aortic position [25]. Established in 2002, the German-Dutch Ross Registry assesses long-term results that
Ó 2014 Informa UK Ltd
ISSN 1477-9072
549
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
Special Report
Weymann, Sabashnikov & Popov
Figure 1. A schematic drawing of pulmonary root harvesting technique. Care should be taken not to harm the left anterior descending coronary artery or its first septal branch.
include data from 12 departments of cardiac surgery since 1988 [26–30]. Until today, increasing numbers of patients have profited from this operation; nonetheless, only a few surgeons have performed it [26–30]. Historic evolution of the Ross procedure
Ross described pulmonary autograft replacement of the aortic valve in patients in 1967 – a pioneering advance that preceded
the era of cardioplegic arrest [31]. The pulmonary valve was excised and implanted in the receiving patient’s aortic root, leaving the coronary ostia complete in their original condition in the aortic root [31]. The biological issues of homograft degeneration are transferred to the low-pressure pulmonary position. Here, optimal valve function plays a lesser role and failure arises gradually [25]. In 1991, Ross presented his findings of the subcoronary implantation technique for the first time [32]. Follow-up studies of 339 patients up to 24 years showed 80% survival rate and 85% freedom from reoperation. Ten years after that first report, more current findings of the first patient group that comprised 131 patients with a mean follow-up of 20 years reported that freedom from reoperation was 76% at 10 years and 62% at 20 years [33] and freedom from autograft replacement was 88% at 10 years and 75% at 20 years. Severe regurgitation of neoaortic valve proved to be the main indication for reoperation in 28 of 30 patients. Freedom from pulmonary homograft replacement was 69% at 25 years [33]. But this technically challenging subcoronary implantation did not achieve extensive attention. Nevertheless, at the end of the 1980s, the Ross procedure experienced a revival when the knowledge of surgeons applying coronary buttons for aortic root operations promoted pulmonary autograft replacement using the full-root technique [34]. This was further facilitated by the publication of excellent midterm results in the 1990s [35]. In the modality of the Ross procedure described here, the complete pulmonary root is implanted into the aortic position after the aortic root is removed, including the re-implantation of the coronary arteries buttons into the neoaortic root. Since this technique is relatively simple to perform in comparison to the subcoronary implantation and consequentially shows more predictable early results, it is widely accepted among cardiac surgeons [35]. Today, most surgeons perform the root replacement technique, whereas the use of the initial subcoronary implantation technique is rarely applied. Surgical technique
Figure 2. A completed Ross procedure with a homograft replacement of the right ventricular outflow tract.
550
A number of reasons are responsible for the initial nonacceptance of the Ross operation. Due to its complexity, the surgeon is obliged to perform an extensive double valve operation. In contrast, a biological or mechanical prosthesis could be inserted in only a third of the operation time. During the learning curve, early morbidity and mortality were considerable [36]. This is no longer the case due to enhanced surgical methods. This operation is suitable for most patients with aortic disease also in the setting of a bicuspid aortic valve and offers a longlasting nonantigenic valve with freedom from thromboembolism or degenerative changes [26–29]. The pulmonary root is excised without harming the left anterior descending coronary artery and its first septal branch, which are in close proximity of the posterior aspect of the valve (FIGURE 1). An aortic or pulmonary homograft replaces the pulmonary valve and artery (FIGURE 2). Subsequently, the pulmonary Expert Rev. Cardiovasc. Ther. 12(5), (2014)
Expert Review of Cardiovascular Therapy Downloaded from informahealthcare.com by Washington University Library on 12/30/14 For personal use only.
The Ross procedure
valve replaces the diseased aortic valve by either full-root replacement [37] or the original subcoronary implantation technique (FIGURES 3 & 4). The left pulmonary sinus should be located in the position of the right coronary sinus, the anterior pulmonary sinus should replace the noncoronary sinus and the right pulmonary sinus should be situated in the former left coronary sinus [38]. Since the pulmonary root is rather thin, there is a risk of bleeding. Alterations to the original technique have focused on that difficulty. For example, the Elkins group in Oklahoma [39] and consequently others [40] applied a ‘root inclusion’ method to insert the pulmonary cylinder where the pulmonary root is implanted within the native aorta while the circumference of the pulmonary outflow is preserved (FIGURE 5). Holes made in the pulmonary arterial wall serve to accommodate the native coronary ostia. This alteration avoids distortion of the commissures, offers external support for the distensible annulus and reduces bleeding [39,40]. Evidently, the Ross procedure commands time, judgment and expertise. Increasing usage has been motivated by enhanced myocardial protection techniques as well as free availability of homograft valves. Currently, it finds application in patients till the age of 60 years, in individual cases up to the age of 70 years, but should be reserved to experienced centers and surgeons [9]. Hemodynamic performance & outcome
In case of imperfect implantation or autograft patient mismatch with a large annulus, early reoperation for aortic regurgitation is the result. Transvalvular gradients are negligible at rest and under conditions of enhanced cardiac output as well as evidently more suited than for any other prosthesis type [41,42]. With the root replacement and in the event of the autograft being implanted as a cylinder, the occurrence of autograft incompetence is almost absent [39,40]. Elkins was mindful of the Ross procedure being contraindicated when the aortic annulus is >27 mm in diameter and spoke out against a mismatch between the autograft and the aortic annulus [39]. In spite of diameter differences, Ross contemplated the pulmonary autograft being applied for aortic root or intra-aortic implantation [43]. Due to the high degree of distensibility of the native, untreated pulmonary arterial wall, the elasticity balances. Since thromboembolism is not the case with the pulmonary autograft, anticoagulation is obsolete in any phase of the treatment [9,26–29]. Brancaccio et al. [18] reported low rates of autograft failure and recommended the Ross procedure as an attractive option for the management of aortic valve disease and complex left ventricular outflow tract obstruction in the pediatric population. Also, it has been proven that the autograft grows in children [44]. Elkins has documented continual size growth of the pulmonary autograft in children, which is proportional to the somatic growth and not likely to be affected by the propensity to stretch [44]. Conclusively, enlargement does not lead per se to significant regurgitation because pulmonary autografts informahealthcare.com
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Figure 3. The classic approach: implantation of the pulmonary autograft using the free-hand subcoronary implantation technique.
with mild regurgitation postoperatively might become entirely competent in the course of somatic growth [44]. Aortic and pulmonary homografts in the right ventricular outflow tract (RVOT) show long-lasting durability [26–29]. Whereas calcification in right-sided homografts is mainly restricted to the graft wall, the valve itself shows an exceptionally low occurrence of calcification and degeneration. Others demonstrated the fate of aortic homografts utilized for right ventricular outflow reconstruction after pulmonary autograft procedures [45]. The occurrence of homograft wall calcification
Figure 4. A detailed presentation of the subcoronary suturing technique.
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Figure 5. Pulmonary autograft implantation as root inclusion.
was only 27% in comparison to patients with right-sided homografts in cyanotic congenital heart disease, where the occurrence was 92% [39]. This is partially because of both the young age of the patients with congenital disease and the incidence of pulmonary hypertension [45]. Hechadi et al. [46] chose an alternative approach to reconstruct the RVOT and applied stentless xenografts. In their study, calcific degeneration was observed in both the pulmonary homografts and the stentless xenografts. Interestingly, calcification progressed more rapidly in the stentless xenograft group than in the pulmonary homograft group. Nevertheless, calcifications affected mainly the wall so that both approaches demonstrated similar and satisfactory hemodynamic outcomes at midto long-term follow-up. They concluded that stentless xenografts can be considered as an acceptable alternative for RVOT reconstruction when pulmonary homografts are not available. Dohmen et al. [47,48] used tissue-engineered heart valves for reconstruction of the RVOT during the Ross operation. They achieved excellent hemodynamic performance during mid- and long-term follow-up. Their concept of decellularization of heart valves and seeding with autologous vascular endothelial cells prevented tissue degeneration and improved valve durability. Fate of the pulmonary autograft
Apparently, the main concern about why the pulmonary autograft is not widely accepted as a substitute valve for aortic valve replacement is based on valve insufficiency, which – after the first 10 years – may occur in more than one-third of the patients [49,50]. 552
Sievers et al. discussed 500 Ross procedures, applying the subcoronary technique, and projected for the long term a lower reoperation rate for aortic regurgitation than for the full-root replacement [16]. De Kerchove et al. concluded that the 10-year rate for both survival and freedom from reoperation was identical for the two techniques [51]. They reported autograft dilation and aortic valve prolapse as the major sources for failure in the full-root and inclusion groups, respectively [16,51]. Consistent with the findings of Elkins et al., autograft dysfunction in the first 6 months is a rather exceptional occurrence [52]. At a midterm follow-up of 2.47 years, echocardiographic assessments of the pulmonary autograft showed a minor aortic insufficiency (graded 1/4) in 39.2 –53.6% of patients [53]. A total amount of 3% of patients showed reasonable insufficiency soon after surgery, accumulating to 14.3% at 5 years. In the long run [54], 86 ± 2% of patients were free from pulmonary autograft failure at 10 years, and 74 ± 5% at 16 years. The numbers for children and young adults were similar. The predictors for late valve dysfunction were female gender, age and dilated aortic valve annulus [54]. Furthermore, David et al. [55] stated that the Ross operation offered inferior outcomes in male patients with aortic insufficiency. In their sequence of more than 200 patients, females with aortic stenosis showed the best results [55]. According to Stewart et al., annuloplasty for dilated aortic annulus during Ross procedure cannot avoid neoaortic regurgitation in children [56]. In comparison, excellent long-term outcomes of the Ross and Ross–Konno operation for infants and children with multilevel left ventricular outflow tract stenosis were observed [57,58]. The autografts were free from stenosis, and the occurrence of regurgitation was small with appropriate enlargement of the annulus similar to the somatic growth [57–60]. Prophylaxis of pulmonary autograft failure
Often, pulmonary autografts become increasingly dilated, which appears to be inevitable [49,50]. Both dilation of the sinotubular junction and aortic annulus can lead to aortic insufficiency. Brown et al. outlined a preventive method of dilation for both sides where a tubular Dacron graft replaces the ascending aorta, and external fixation of the aortic annulus is added with a Dacron strip (FIGURE 6). Moreover, they stress the importance of an aggressive treatment of postoperative systemic hypertension [61,62]. In order to support the distensible root, Pacifico et al. [63] applied a circumferential wrap of bovine pericardium. Ungerleider et al. [64] entirely enclosed the autograft in a suitably sized Dacron graft before implantation to prevent autograft dilation. Using a comparable method, other surgeons applied Goretex [65] or a Valsalva graft [66] for equal purpose. David et al. [67] introduced dilatation of the pulmonary autograft as outcome of a mismatch between the diameters of the annulus and the sinotubular junction of the aortic and pulmonary roots. In fact, referring to this divergence in diameter, per-surgical adjustments at the annulus and sinotubular junction did not turn out to prevent late dilatation of the homograft [67]. Expert Rev. Cardiovasc. Ther. 12(5), (2014)
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The Ross procedure
Special Report
In comparison to the study of David et al. [67], Lansac took one further step by integrating the notion of compliant sinuses as most imperative support of aortic root hemodynamics in his examinations of the Ross procedure [68]. At the level of the commissures and sinotubular junction, the dynamic differences observed between the pulmonary and the aortic roots were regarded as a possible predicting factor for subsequent dilatation. These could serve as an explanation for global pulmonary root dilatation when exposed to systemic pressure. Indeed, the conclusion could be drawn that these results of Lansac et al. emphasize the significance of a supra-aortic ridge for appropriate valve competency as well as the necessity for surgical techniques developed to support this region of the autograft. Strategies for autograft failure
Mechanical or bioprosthetic valves have been applied to replace failed pulmonary autografts with or without aortic root replacement [69]. Nevertheless, current progress in valve-sparing aortic root replacement has promoted the implementation of this technique to treat pulmonary autograft insufficiency mainly in the case of failed full-root implantation technique. Luciani et al. applied the Yacoub method for valve-sparing aortic root surgery to address failed pulmonary autografts and named it the Ross–Yacoub procedure [70]. Kerchove et al. repaired dilated autografts using valve-sparing root replacement or ascending aorta replacement. Moreover, they also applied in their series aortic repair techniques on the failed pulmonary autografts like commissural resuspension, free margin plication or resuspension with polytetrafluoroethylene [71]. Expert commentary
In summary, the pulmonary autograft demonstrates low rates of degeneration, endocarditis and thromboembolism for a period >20 years compared with current biological or mechanical replacement valves. Main complications of the procedure are calcific degeneration of the homograft in the RVOT position and pulmonary autograft regurgitation, which is mainly technical in nature. The most reasonable candidates for the Ross procedure are women of childbearing age with aortic stenosis as well as adults with an active lifestyle and a life expectancy of over 20 years. Moreover, infants and small children with left ventricular outflow tract stenosis benefit clearly from a Ross–Konno procedure. A technique to avoid aortic annular dilation should be applied from the very beginning during autograft implantation to warrant excellent long-term results. In our opinion, the Ross procedure is best suited to centers where the expertise exists in daily management. For this reason, regionalization is appropriate to ensure that adequate volumes are present at each specialized center. Given the complexity of the operation, special training is mandatory. Five-year view
Without doubt, the Ross procedure provides excellent results in terms of hemodynamic flow characteristics, autograft function, including potential for growth, patient survival and low informahealthcare.com
Figure 6. An intraoperative image depicting external fixation of the neoaortic root with a Dacron strip to avoid dilatation.
incidence of embolic complications. In the next 5 years, more follow-up studies with larger patient numbers will be available for final judgment of this technique. In future, reinterventions on the right ventricular outflow will be an excellent target for percutaneous [72] and tissue-engineered pulmonary valve replacement [9,47,48]. Moreover, reoperations on the autograft may be increasingly required in the long term (>20 years), but due to advances in valve-sparing techniques, preservation of the living autograft will be possible in experienced hands. Furthermore, the future will show whether improvements in aortic valve repair and developments in valve technology may offer a better alternative to the Ross procedure. Acknowledgements
The authors would like to thank Mrs. Kreutzer for the preparation of the schematic drawings. Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript. 553
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Key issues • Autograft regurgitation remains the crucial weak point of the Ross procedure. • The long-term success of external support techniques to prevent autograft regurgitation in adults is unknown. • Alternative techniques for right ventricular outflow tract reconstruction must be taken into consideration, such as implantation of tissueengineered valves, to improve long-term results. • It is to be expected that future bioprosthetic valves will demonstrate improved long-term results in the aortic position so that the Ross
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procedure may lose its important position in aortic valve surgery.
References
10.
Weymann A, Schmack B, Okada T, et al. Reendothelialization of human heart valve neoscaffolds using umbilical cord-derived endothelial cells. Circ J 2013;77(1):207-16
20.
Brown JW, Patel PM, Rodefeld MD, Turrentine MW. The Ross operation in adolescents. World J Pediatr Congenit Heart Surg 2013;4(4):403-11
11.
Honge JL, Funder J, Hansen E, et al. Recellularization of aortic valves in pigs. Eur J Cardiothorac Surg 2011;39(6):829-34
21.
12.
Massel DR, Little SH. Antiplatelet and anticoagulation for patients with prosthetic heart valves. Cochrane Database Syst Rev 2013;7:CD003464
Schmidtke C, Dahmen G, Sievers HH. Subcoronary Ross procedure in patients with active endocarditis. Ann Thorac Surg 2007;83(1):36-9
••
Single-center study which confirms excellent outcomes of the Ross procedure in active endocarditis.
22.
Hamm CW, Mollmann H, Holzhey D, et al. The German Aortic Valve Registry (GARY): in-hospital outcome. Eur Heart J 2013. [Epub ahead to print]
23.
Andreas M, Wiedemann D, Seebacher G, et al. The Ross procedure offers excellent survival compared with mechanical aortic valve replacement in a real-world setting. Eur J Cardiothorac Surg 2014. [Epub ahead to print]
Papers of special note have been highlighted as: • of interest •• of considerable interest 1.
2.
Une D, Ruel M, David TE. Twenty-year durability of the aortic Hancock II bioprosthesis in young patients: is it durable enough? Eur J Cardiothorac Surg 2014. [Epub ahead of print] McClure RS, McGurk S, Cevasco M, et al. Late outcomes comparison of nonelderly patients with stented bioprosthetic and mechanical valves in the aortic position: a propensity-matched analysis. J Thorac Cardiovasc Surg 2014. [Epub ahead of print]
13.
Halbritter K, Beyer-Westendorf J, Nowotny J, et al. Hospitalization for vitamin-K-antagonist-related bleeding: treatment patterns and outcome. J Thromb Haemost 2013;11(4):651-9
3.
Bouhout I, Stevens LM, Mazine A, et al. Long-term outcomes after elective isolated mechanical aortic valve replacement in young adults. J Thorac Cardiovasc Surg 2013. [Epub ahead of print]
14.
Gabbieri D, Dohmen PM, Linneweber J, et al. Early outcome after surgery for active native and prosthetic aortic valve endocarditis. J Heart Valve Dis 2008;17(5): 508-24; discussion 525
4.
Celiento M, Filaferro L, Milano AD, et al. Single center experience with the Sorin Bicarbon prosthesis: a 17-year clinical follow-up. J Thorac Cardiovasc Surg 2013. [Epub ahead of print]
15.
24.
5.
Bouchard D, Mazine A, Stevens LM, et al. Twenty-year experience with the carbomedics mechanical valve prosthesis. Ann Thorac Surg 2013;97(3):816-23
Maciejewski M, Piestrzeniewicz K, Bielecka-Dabrowa A, Walczak A. Biological artificial valve dysfunction - single-centre, observational echocardiographic study in patients operated on before age 65 years. Arch Med Sci 2011;7(6):993-9
El-Hamamsy I, Eryigit Z, Stevens LM, et al. Long-term outcomes after autograft versus homograft aortic root replacement in adults with aortic valve disease: a randomised controlled trial. Lancet 2010; 376(9740):524-31
16.
Sievers HH, Stierle U, Charitos EI, et al. Fourteen years’ experience with 501 subcoronary Ross procedures: surgical details and results. J Thorac Cardiovasc Surg 2010; 140(4):816-22.822 e811-815
25.
••
One of the largest reports on subcoronary Ross procedure, which deserves the ‘standard status’ against all other reported series on this technique.
Brown JW, Ruzmetov M, Fukui T, et al. Fate of the autograft and homograft following Ross aortic valve replacement: reoperative frequency, outcome, and management. J Heart Valve Dis 2006;15(2): 253-9; discussion 259-260
26.
Charitos EI, Hanke T, Stierle U, et al. Autograft reinforcement to preserve autograft function after the Ross procedure: a report from the German-Dutch Ross registry. Circulation 2009;120(Suppl 11): S146-54
6.
Sansone F, Dato GM, Zingarelli E, et al. Long-term follow-up of stentless prosthesis. J Cardiol 2013. [Epub ahead of print]
7.
Chan V, Kulik A, Tran A, et al. Long-term clinical and hemodynamic performance of the Hancock II versus the Perimount aortic bioprostheses. Circulation 2010; 122(Suppl 11):S10-16
8.
9.
Ruel M, Chan V, Bedard P, et al. Very long-term survival implications of heart valve replacement with tissue versus mechanical prostheses in adults
