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Ann Thorac Surg 2005;80:2271-2277
© 2005 The Society of Thoracic Surgeons
Division of Cardiac Surgery, University of Verona, Verona, Italy
Accepted for publication March 3, 2005.
* Address correspondence to Dr Luciani, Division of Cardiac Surgery, University of Verona, O. C. M. Piazzale Stefani 1, Verona, 37126 Italy (Email: gbluciani{at}yahoo.com).
| PEDIATRIC CARDIAC SURGERY: To participate in The Annals of Thoracic Surgery CME Program, please visit http://cme.ctsnetjournals.org.
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsCommentReferences |
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METHODS: Ninety male and 22 female patients, aged 29 ± 10 years (range, 6–49) underwent cross-sectional clinic and echocardiographic examination. Indication for Ross operation was aortic regurgitation in 79 patients, stenosis in 11, and mixed lesion in 22; 82 (73%) had a bicuspid valve. Endpoints of the study were survival and freedom from autograft dilatation, from autograft and homograft dysfunction, and from reoperation.
RESULTS: There was 1 (1%) hospital and 1 late (1%) death, during an average follow-up of 5.1 ± 1.9 years (range, 0.1–10.6). At 10 years, survival was 98 ± 2%. Late autograft dilatation was identified in 32 (29%) patients and regurgitation in 15 (14%), 7 of whom had autograft dilatation. Ten-year freedom from autograft dilatation was 43 ± 8% and from regurgitation was 75 ± 8%. Multivariate analysis showed younger age (p = 0.05), preoperative aortic root dilatation (p = 0.02), root replacement technique (p = 0.03), and absence of pericardial strip buttressing (p = 0.04) to be predictive of autograft dilatation. Eleven (10%) patients required reoperation on the autograft (8 prosthetic valve replacement, 3 autograft root repair). Ten-year freedom from reoperation was 72 ± 10% and from replacement of the autograft was 88 ± 5%. Pulmonary homograft obstruction was identified in 6 (5%) patients, requiring homograft replacement in 1. All but 2 (2%) patients were in New York Heart Association class I, with a return to regular school grade or active employment.
CONCLUSIONS: Late outcome for the Ross procedure is excellent in terms of survival and quality of life. Late root dilatation, autograft regurgitation, and homograft stenosis, however, show increasing prevalence with time. Technical modifications of the procedure, yearly aortic root imaging, and early reintervention on the dilated neoaortic root may further enhance the durability of the autologous pulmonary valve.
For decades mechanical prostheses have been considered the substitute of choice for the irreparable diseased aortic valve in children and young adults alike (1–3). Theoretically, unlimited durability and widespread availability in all sizes were the superior qualities of these prostheses when compared with experience with homografts and xenografts, both exposed to premature structural deterioration in the young patient [4, 5]. The recent revival of the Ross operation in adults has promoted an extension of the operation to the pediatric population, beginning with the late 80s and early 90s [6]. Enthusiasm for midterm clinical results has turned this complex procedure into the operation of choice for young patients requiring aortic valve replacement at many centers worldwide [7]. Controversy on the ideal valve substitute in this age group, however, continues to the present [2, 3, 8]. At the University of Verona, we have reserved the Ross operation for children and young adults with aortic valve disease not amenable to other reparative procedures. Here, we report the 10-year experience with such a treatment strategy.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Between May 1994 and December 2004, 112 consecutive patients consented to and underwent the Ross operation at our institution; 18 (16%) were children in the growing age (6–18 years). Demographic data are reported in Table 1. It is apparent that the majority of patients presented valve insufficiency as indication to surgery and that 
of patients had bicuspid aortic valve (BAV). This explains the relatively common finding of a dilated or even aneurysmal ascending aorta at the time of surgery. A more limited proportion of patients had undergone one or more prior operative cardiac procedures.
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Echocardiographic Data and Measurements
All patients underwent transthoracic echocardiographic examinations at discharge and were scheduled on a yearly basis thereafter. Due to the widespread geographic origin of patients, this program was inconsistently respected. This resulted in 35 patients with 3 or more follow-up echocardiographic examinations, 56 with two, and 111 with one, as specified below. For the latter reason and to eliminate interobserver variability, cross-sectional follow-up echocardiographic investigation was undertaken by the same experienced sonographer at our institution. Transthoracic echocardiograms were performed with 2.5-MHz ultrasound transducers (Hewlett-Packard Sonos 2500 system; Hewlett-Packard, Andover, MA) and recorded on VHS videotape. Average values of 5 consecutive beats were taken for dimensions and pressure gradients.
Two-Dimensional Echocardiography
Autograft dimensions were measured as described by Roman and colleagues [9] at four different levels: (1) aortoventricular junction (aortic annulus), at the level of the autograft leaflet hinges; (2) sinus of Valsalva, at the largest anteroposterior diameter; (3) sinotubular junction, at the distal rim of the sinuses of Valsalva; and (4) proximal ascending aorta, 2 cm above the sinotubular junction. Due to the recognized tendency of the autograft root to remodel after implant [10], the sinus of Valsalva and the sinotubular junction often assumed similar dimensions. In these cases, the sinus portion was arbitrarily measured 2 cm above the aortic annulus, the sinotubular junction 2 cm above the sinus, and the ascending aorta 2 cm above the sinotubular junction. Measurements of diameters were made in the parasternal long-axis view of the aorta at enddiastole.
Continuous-Wave, Pulsed, and Color Flow Doppler
Aortic regurgitation was assessed by multiple techniques with the apical five-chamber view: pulsed wave Doppler,and color flow Doppler imaging were used for mapping the left ventricular outflow tract, including determination of ratio of jet height to left ventricular outflow tract height; continuous Doppler imaging was applied to measure the deceleration slope and pressure half-time of the aortic regurgitant jet. Aortic insufficiency was graded with the use of standard criteria [11]. Pulmonary homograft, or other right ventricular-pulmonary artery conduit when present, was also studied focusing on valve insufficiency and degree of transvalvar obstruction. The latter was graded as mild (peak pressure gradient < 30 mm Hg), moderate (30–50 mm Hg), and severe (> 50 mm Hg), in line with prior studies [12].
Clinical Follow-Up
In the present cross-sectional follow-up study (mean duration, 5.1 ± 1.9; range, 0.1–10.6 years), all 111 operative survivors (100%) were assessed by means of direct physical examination at our clinic, in conjunction with echocardiographic evaluation. Follow-up closure was between October and December 2004.
Statistical Analysis
Categorical variables are reported as absolute numbers and percentage. Continuous variables are expressed as means ± standard deviation. Time-related events were described using the Kaplan-Meier estimate. Primary endpoints of the study were the following: survival, freedom from autograft dilatation (root diameter 0.21 cm/m2 at any of the four levels examined), from autograft dysfunction (moderate or greater valve regurgitation), from homograft dysfunction (moderate or greater valve regurgitation and/or moderate or greater valve stenosis), from reoperation on the autograft, from reoperation on the homograft, and from other major adverse cardiovascular events (MACE) (heart failure, myocardial infarction, endocarditis, thromboembolism, hemorrhage). Secondary endpoints included quality of life indices such as New York Heart Association (NYHA) class, school grade, employment, and regular and strenuous physical activity. Multivariate analysis was performed using the logistic regression method and the Cox proportional hazard method to identify risk factors for time-related occurrence of autograft dilatation and autograft regurgitation. Variables entered in the analysis included age, sex, body surface area, diagnosis (regurgitation, stenosis, mixed), bicuspid aortic valve, prior aortic procedure, operative technique (subcoronary, cylinder inclusion, root replacement), use of pericardial strips, associated procedure, length of follow-up, preoperative and postoperative diameters of aortic annulus, sinus of Valsalva, sinotubular junction, and ascending aorta. Significance was inferred at a p value less than 0.05.
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Results |
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Other MACE and Quality of Life
No adverse cardiovascular events, other than dysfunction of or reoperation on the autograft or homograft as described above, were recorded in any of the patients during follow-up. One hundred and two patients carrying an autograft valve remain at risk as of December 2004: 100 of them (98%) are in NYHA class I and all have resumed normal lifestyles, including regular schooling (children and adolescents) and active employment (adults). Eighty-two patients (80%) reported regular physical activity and 20 (20%) reported strenuous activity.
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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A vast body of literature is currently available, which shows that mechanical devices definitely allow associated cardiac procedures on the left heart, when needed, and allow satisfactory survival in children [1–3, 8]. Hospital mortality, generally higher than for elective mechanical valve replacement in adults, ranges from 5% to 13%, reflecting more demographic and operative variables (age, severity of left ventricular dysfunction, number and type of prior operations, need for associated procedures) than early morbidity of the device per se [1–3, 8]. Therefore, hospital mortality represents an inadequate parameter to compare clinical outcome with different valve substitutes. This limitation notwithstanding, it is apparent that aortic valve replacement with pulmonary autografts does not result in increased operative mortality in the present, as well as in prior, clinical series [6, 7, 13]. The particularly low mortality in the current experience may further be explained by the absence of small infants requiring complex associated procedures (ie, the Ross-Konno).
Late survival after mechanical aortic valve replacement in children has also been recently well documented [2, 3]. Similar very long-term follow-up data are not available for children and young adults having the Ross operation, as worldwide revival of the procedure began in the late eighties and early nineties [6, 7, 8, 14]. In addition, rigorous comparison of late survival is complicated by the fact that Ross clinical series, such as the one herein, often include young adult patients, who, on the contrary, are generally grouped into clinical series of adult mechanical valve replacement. Furthermore, separate analysis of late outcome in adolescents and young adults after mechanical aortic valve replacement has seldom been carried out [15–17]. Taking all these restrictions into account, 10-year survival after the Ross procedure in the young is in excess of 95% in most series [6–8], including the present. This result favorably compares with results after mechanical valve replacement both in children [1–3] and in young adults [15–17].
Aside from the complexity of the operation, fundamental objection to the Ross procedure is the conversion from one-valve to two-valve disease, due to the sacrifice of the autologous pulmonary valve and the need to replace it [2, 3]. Accordingly, late adverse events involving both the pulmonary autograft and the pulmonary homograft after the Ross operation have been reported [12, 14, 18, 19].
Dilatation of the pulmonary autograft, particularly when implanted as a free standing root, is possibly the most common late complication [14, 19]. Whereas dilatation may only represent an acute postoperative remodeling process in most patients [10], in some it may be progressive, eventually leading to aneurysm formation, valve insufficiency and, rarely, dissection [14, 19–21]. The present experience confirms prior findings demonstrating that progression of root dilatation to aneurysm affects a minority (5%) of patients at 10 years. The possibility that progressive dilatation may lead to valve insufficiency, however, may exist even for smaller (ie, less than 5 cm) root diameters, as up to 1/5 of patients with autograft root larger than 4 cm show relevant aortic regurgitation [21]. Resection of preoperative aortic aneurysm, rather than simple tailoring aortoplasty, avoidance of the free-standing root technique and, when inevitable, use of root stabilization measures, are likely to reduce prevalence of dilatation, as shown by multivariate analysis. This observation is supported by a recent report by Kouchoukos and colleagues [21] showing a disappointingly high (15%) prevalence of reoperation at a mean follow-up of 6 years after root replacement, primarily due to autograft root dilatation and regurgitation. It is apparent that mechanical aortic valve replacement is not associated with root dilatation per se. However, in a significant proportion of young patients with congenital (ie, bicuspid) aortic valve disease, moderate root dilatation does progress with time after valve surgery, eventually leading to root replacement for aneurysm or dissection [22]. Therefore, the problem of evolution of root pathology in such patients exists regardless of the type of substitute used to replace the native aortic valve.
Dysfunction of the pulmonary autograft is the second most common complication in the present series, as well as in prior ones [6, 21, 23]. Similar to prior observations, technical complications resulting in valve insufficiency occurred with any of the methods used to implant the pulmonary autograft, albeit to a limited extent in the current analysis (early reoperation rate of 3%). Aside from neoaortic root dilatation, the second most common cause of late valve dysfunction was leaflet prolapse, particularly with the cylinder inclusion technique. Late freedom from valve dysfunction is comparable with aortic homografts [15], but clearly worse than what is reported after mechanical valve replacement [2, 3], which are very rarely affected by structural deterioration. Nonstructural deterioration (ie, pannus formation, obstruction due to patient-prosthesis mismatch, periprosthetic leak), on the contrary, is possible with mechanical prostheses, particularly in children and young adults [2, 3]. The observation that late valve insufficiency is more common in patients with preoperative aneurysm and follow-up dilatation of the sinus of Valsalva and sinotubular junction of the autograft agrees well with the findings of other studies [19–21]. The present experience with autograft dilatation and dysfunction has led us to the current policy of using the subcoronary and cylinder inclusion techniques in adults, while reserving free-standing root replacement for growing children. In addition, coexisting ascending aortic aneurysms are managed by resection and graft interposition.
A corollary to the observations on autograft dilatation and dysfunction is the need for reoperation on the autograft. The 10-year freedom from reoperation observed herein may well be regarded as less than optimal when compared to clinical series with mechanical prostheses in young adults [15, 16], although absolutely similar to estimates using mechanical valves in children [2, 3]. A higher risk of nonstructural failure in children due to pannus, somatic growth, or endocarditis explains this observation and justifies a 10-year freedom from reoperation of 80% in the series of Brown and colleagues [2] and of 86% in the series of Alexiou and colleagues [3]. Furthermore, for young women in childbearing age (mean age, 25 years) valve loss due to reoperation or valve-related death is greater with mechanical prostheses when compared with human tissue valves (homografts, autografts) [17]. Thus, information on late freedom from reoperation in young adults carrying mechanical prostheses is still controversial, possibly reflecting different demographic variables (age, sex) in the reported series [15–17]. Comparison of pulmonary autografts with aortic homografts is also favorable, as freedom from reoperation in the growing child is dismal [5, 13], and in the adult it is at best similar [8, 24]. Finally, early reintervention on dilated autograft roots may allow preservation of the autograft valve in a significant number of patients by remodeling of the sinotubular junction or of the entire aortic root, as dictated by the individual anatomic findings. Accordingly, elective root reoperation in the present experience resulted in valve preservation in 3 of 5 patients, thereby realizing a 10-year freedom from autograft valve replacement of 88%. It must be emphasized that key to limiting morbidity and mortality of the, often complex, reintervention on the pulmonary autograft is continued referral to the original center where the Ross procedure was performed.
Contrary to prior reports [12] and to the general expectation of significant morbidity associated with the use of pulmonary homografts for right-heart repair, homograft dysfunction was limited and led to reoperation only in 1 patient in the present 10-year experience. The negligible occurrence of severe obstruction in the present study contrasts with the 6% finding reported by Carr-White and colleagues [12]. Whether the common use of homovital or fresh antibiotic sterilized homografts in the latter experience, as opposed to the routine use of cryopreserved homografts in our own, may explain this discrepancy is a matter of speculation.
Similarly rewarding has been the complete freedom from any other MACE in this population of young patients, allowing for a quality of life comparable to age-matched healthy individuals. In spite of satisfactory survival estimates using mechanical prostheses in children [3], and often excellent in young adults [15, 16], thromboembolic and, less commonly hemorrhagic, complications continue to pose serious, time-dependent hazards in most clinical series. Fifteen or even twenty-year freedom from thromboembolic events in the 90% range must be regarded with concern, considering the peculiar life-style needs in this age group. In addition, whether the impact of certainly invalidating, if not potentially lethal, events truly does not influence late survival remains controversial, as valve-related mortality is higher in young women carrying mechanical prostheses [17]. Equally important in guaranteeing a satisfactory functional status is the ability of pulmonary autograft to enhance rapid regression of left ventricular hypertrophy and restoration of ventricular dimensions after valve replacement [6, 7]. On the contrary, persistence of patient-prosthesis mismatch, resulting in moderate or high resting transvalvar gradients, as shown with mechanical prostheses in children [3], represents a worrisome finding when looking at all the normal activities (sport, pregnancy, recreation) that the life of a young individual must encompass.
Limitations
The present analysis shares all limitations inherent with retrospective clinical studies. In addition, nonrandom use of three different surgical techniques may weaken the inferences that can be drawn from clinical results. At the same time, however, it allows speculation on differential outcome with the various operative methods, otherwise not feasible. Last, due to the broad definition of the patient population (young; ie, less than 40 years of age) direct comparison with prior series is often cumbersome, as other studies are focused either on pediatric (less than 18 years of age) or young adult (less than 40 or even 50 years of age) patients.
Conclusions
Ten years after the start of a clinical program of aortic valve replacement with the pulmonary autograft, at our institution this continues to be the preferred surgical option in the child and young adult due to unsurpassed survival and quality of life. Late complications, mostly confined to the autograft root, emerge with time after operation, but may be limited by careful operative planning and regular follow-up imaging.1
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