| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
J Thorac Cardiovasc Surg 2008;135:552-559
© 2008 The American Association for Thoracic Surgery
Surgery for Congenital Heart Disease |
a Department of Cardiac Surgery, Children's Hospital Boston and Harvard Medical School, Boston, Mass
b Department of Cardiology, Children's Hospital Boston and Harvard Medical School, Boston, Mass
c Division of Pediatric Cardiothoracic Surgery, University of Texas Southwestern Medical Center and Children's Medical Center, Dallas, Tex
d Division of Cardiovascular Surgery, Children's National Medical Center, Washington, DC
Received for publication July 17, 2007; revisions received September 11, 2007; accepted for publication September 26, 2007. * Address for reprints: Doff B. McElhinney, MD, Department of Cardiology, Children's Hospital, Boston, MA 02115. (Email: doff.mcelhinney{at}cardio.chboston.org).
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
Methods: From 1989 to 2005, a total of 81 patients younger than 19 years with moderate or severe aortic regurgitation underwent surgical aortic valvuloplasty. Aortic regurgitation was congenital in 20 cases, after treatment of aortic stenosis in 30, from other injuries to the aortic valve in 12, and from other causes in 19. Eighteen patients had moderate or severe aortic stenosis. Preoperative left ventricular end-diastolic dimension z score was 4.9 ± 2.7.
Results: After surgical aortic valvuloplasty with various techniques, including pericardial leaflet augmentation in 80%, aortic regurgitation was improved in 77 patients and was mild or less in 68. Ten of 18 patients with moderate or severe aortic stenosis before repair had a decrease to mild, whereas 2 had progression from mild to moderate. Left ventricular end-diastolic dimension z score decreased by 2.9 ± 2.1 (P < .001). During follow-up (median 4.7 years), 33 patients underwent aortic valve reinterventions, including aortic valve replacement in 25. Estimated freedoms from aortic valve replacement were 72% ± 6% at 5 years and 54% ± 9% at 7.5 years and were shorter in patients with moderate or severe aortic stenosis before surgical aortic valvuloplasty. Among surviving patients who did not undergo aortic valve replacement, aortic regurgitation at follow-up was moderate in 21 and trivial or mild in 34; left ventricular and aortic root dimensions were preserved.
Conclusion: Surgical aortic valvuloplasty is a valid option with good intermediate results for children and adolescents with aortic regurgitation from a variety of causes, particularly for patients with less than moderate aortic stenosis.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
|
|
Several surgical options are available for the treatment of aortic regurgitation (AR) in young patients, including various techniques of aortic valve repair, or surgical aortic valvuloplasty (SAVP), and aortic valve replacement (AVR) with mechanical,1,2
bioprosthetic,3,4 or autologous pulmonary5,6 valves. SAVP may have particularly important advantages in children relative to the alternatives, including freedom from the risks of a small mechanical prosthesis, avoidance of anticoagulation, and avoidance of the drawbacks of an autograft AVR, such as aortic root dilation and need for a right ventricle–pulmonary artery conduit. The apparent advantages of SAVP in young patients depend, however, on low morbidity and durable aortic valve function after repair. To date, few reports of SAVP in children, most with small numbers of patients and limited follow-up, have been published.7-14 The purpose of this study was to analyze results of SAVP in a large number of children and young patients with AR and to explore factors associated with improved outcome.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
Patients
The Cardiovascular Program database at Children's Hospital (Boston, Mass) was queried for children and adolescents (<19 years) who underwent SAVP for AR with or without associated valvular aortic stenosis (AS) from 1989 to 2005. Only patients who underwent repair of the aortic valve were included. Patients who had only a root reduction or annular plication without alteration of the valve leaflets were excluded. Other exclusion criteria included the following: a univentricular circulation, a morphologically right ventricle functioning as the systemic ventricle, and other associated causes of left ventricular (LV) volume overload, such as a ventricular septal defect or significant mitral regurgitation. Patients with an anatomic pulmonary or truncal valve in the aortic position were included if they did not meet other exclusion criteria. The decision to undertake surgery was based on the judgment of the treating physicians and not necessarily on strict anatomic or functional criteria. Cross-sectional follow-up was obtained by April 2007.
Classification of AR
The causes of AR were classified as follows: (1) congenital, (2) resulting from transcatheter or surgical treatment of congenital valvular AS, (3) caused by trauma during other cardiac interventions, (4) caused by endocarditis or rheumatic heart disease, (5) related to abnormal truncal valve, and (6) resulting from dilation or distortion of the neoaortic root or an abnormal neoaortic (native pulmonary) valve after arterial switch operation.
Echocardiographic Measurements
Aortic valve function and dimensions
AR was graded echocardiographically according to a composite assessment scale as none or trivial, mild (no LV dilation, no retrograde flow in the descending aorta, AR vena contracta width <4 mm), moderate (LV end-diastolic volume or LV end-diastolic dimension [LVEDD] z score >2 and <4, retrograde flow in the descending aorta, vena contracta 4–6 mm), or severe (LV end-diastolic volume or LVEDD z score >4, retrograde flow in the descending aorta, vena contracta >6 mm).
Valvular AS was estimated by Doppler evaluation from multiple views, and the highest maximum instantaneous gradient was recorded. AS was categorized as moderate or greater (gradient >50 mm Hg) or less than moderate (
50 mm Hg). Aortic valve annulus and root diameters were measured from parasternal long-axis images, with the root diameter taken as the maximum dimension at the level of the sinuses. These measurements were indexed to body surface area and reported as z scores.
Ventricular dimensions and function
LV dimensions, volumes, mass, and fractional shortening (LVFS) were measured and calculated from apical four-chamber and cross-sectional echocardiographic images,15 indexed to body surface area, and reported as z scores. Short-axis LVEDD and LV end-systolic dimension were measured. In some studies, LV end-diastolic volume and LV end-systolic volume were also calculated. Because LV volumes were assessed adequately at the desired time points for fewer patients than were LV linear dimensions, however, only LVEDD and LV end-systolic dimension z scores were used for analysis.
Aortic Valvuloplasty
A variety of aortic valvuloplasty techniques were used, with multiple techniques often used in a single patient. Most of these, or variations thereof, have been described previously.7-13 These were categorized as pericardial augmentation or extension of leaflets, creation of a leaflet, repair of a torn or perforated leaflet, reattachment or resuspension of a dehisced or prolapsing leaflet, and commissuroplasty. Pericardial augmentation or extension consisted of a variety of techniques, including augmentation of prolapsing or deficient leaflets, use of a pericardial patch to close a rudimentary commissure or combine a rudimentary leaflet with a larger leaflet, and extension of leaflets, usually after excision of thickened or malformed edges. Autologous pericardium was fixed in 0.6% glutaraldehyde for 5 to 10 minutes. Creation of a leaflet was used to replace absent or severely deficient leaflet tissue that was resected; it involved fashioning a patch of autologous pericardium into a leaflet, which was then sutured to the aortic root. Closure of perforated or torn leaflets involved either direct suture closure or closure with a pericardial patch. Reattachment or resuspension of leaflets involved reattachment of dehisced leaflets, resuspension of prolapsing leaflets, or reattachment of leaflets deliberately separated from the aortic wall to resect a rudimentary leaflet and plicate a dilated aortic root (mostly in patients with truncus arteriosus). Commissuroplasty involved repair or tightening of commissures with mattress sutures placed from outside the aorta to inside the lumen. Patients with coexisting AS often underwent commissurotomy along with the listed valvuloplasty techniques. Thinning of leaflets was frequently performed in conjunction with these techniques and was not specified separately.
Intraoperative transesophageal echocardiography was typically used, particularly during the latter part of our experience, to assess the repair and guide revision if necessary. In our more recent experience, preoperative and intraoperative 3-dimensional echocardiography was frequently used to define the anatomy of the regurgitant valve and to assess the repair (
Figure 1).
|
2 analyses, respectively, were used. For comparison of preoperative and postoperative data within patients, paired t test analysis was used. Multivariable analysis of discrete outcomes was performed with multiple logistic regression. Correlation between continuous variables was assessed with linear regression. Data are presented as mean ± SD or median with range. |
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
Twenty-three patients (28%) were infants and children younger than 5 years, 29 (36%) were children between 5 and 11 years old, and 29 (36%) were adolescents (>11 and <19 years). Sixty-two patients (77%) had associated cardiovascular anomalies, and 57 (70%) had undergone at least one previous intervention (Table E1).
Severity and Causes of AR
Preoperative AR was severe in 52 patients (64%) and moderate in 29 (36%). The distribution of different etiologies of AR is summarized in
Table 1. Among patients with congenital AR, 1 had a quadrileaflet aortic valve with partial deficiency of multiple leaflets, 3 had a completely absent right coronary leaflet, 5 had a tricommissural valve with deficiency of 1 or more leaflets (usually the right or noncoronary leaflets), 1 had a unicommissural valve and central deficiency, and the remaining patients had a bicommissural valve with central deficiency. In all but 1 of these patients, the AR emanated from the area of the right or noncoronary cusp.
|
Among patients with AR caused by intervention for congenital AS, the most recent AS procedure was a median of 3.6 years (10 days–14 years) before SAVP. Among patients with AR resulting from other types of valve injury, the procedure causing valve damage was a median of 3.5 years (1 day–9 years) before SAVP.
Preoperative AS
Moderate or greater AS was present in 18 patients (22%): 15 with AR after previous treatment of AS (P < .001 vs other causes), 2 with congenital AR, and 1 with truncus arteriosus. Patients with moderate or greater pre-SAVP AS were more likely to have moderate AR than severe AR (11 of 29 with moderate AR vs 7 of 52 with severe AR, P = .01) and had lower z scores for both aortic annulus diameter (1.1 ± 1.6 vs 3.9 ± 3.2, P = .001) and LVEDD (2.9 ± 2.1 vs 5.5 ± 2.5, P < .001) than patients without significant AS.
LV Dimensions and Function
LV dimensions and function at baseline are summarized in Table E2. Pre-SAVP LV dilation was less severe in younger (<5 years) patients than in older patients (LVEDD z score 3.7 ± 1.2 vs 5.3 ± 2.9, P = .02), in patients with moderate AR than in those with severe AR (LVEDD z score 5.8 ± 2.4 vs 2.9 ± 2.1, P < .001), in and patients with at least moderate AS than in those with mild or no AS (LVEDD z score 2.9 ± 2.1 vs 5.5 ± 2.5, P < .001). Seven patients, all with moderate AR, had a normal pre-SAVP LVEDD z score (<2); 5 had moderate or greater AS and 2 had AR caused by aortic valve injury during surgery for other anomalies.
Aortic Valvuloplasty
Surgical procedures on the aortic valve are summarized in
Table 2. In 80% of patients, including 28 of 30 with AR after treatment of AS, leaflets were augmented or extended with pericardium, often in conjunction with other techniques. Additional procedures were performed in 25 patients (Table 3).
|
Postoperative AR
Early after SAVP (1–26 days), AR was improved in 77 patients (95%): by 1 grade in 19 patients, by 2 grades in 46, and by 3 or 4 grades in 12. AR was trivial or none in 22 patients (27%), mild in 46 (57%), moderate in 13 (16%), and severe in none. None of the variables analyzed were associated with worse postoperative AR.
At most recent follow-up of the 78 surviving patients (before AVR if applicable), the degree of AR was severe in 11 patients, moderate in 32, and trivial or mild in 35. Among the 55 surviving patients that did not undergo AVR, a median of 4.2 years after repair (1 month–12 years), the degree of AR was moderate in 21 and trivial or mild in 34.
Follow-up aortic root diameter z scores, including measurements before surgery for patients who underwent AVR, did not differ from pre-SAVP z scores (P = .45). One patient who underwent AVR had endocarditis diagnosed 4.4 years after SAVP.
Postoperative AS
Among 18 patients with at least moderate AS before SAVP, 10 (56%) had a decrease to mild or less in the early post-SAVP period and 8 continued to have moderate AS. There was a trend toward lower aortic annulus z scores among the 8 patients whose AS did not improve (median z score 0.8 vs 2.2, P = .11). Two patients with less than moderate AS before SAVP had an increase to moderate AS in the early post-SAVP period. According to multivariable logistic regression, the only factor associated with moderate or greater postoperative AS was moderate or greater preoperative AS (P < .001).
Eight patients with less than moderate AS both before SAVP and early after SAVP had a diagnosis of moderate or greater AS a median of 3 years (0.5–6 years) after SAVP. Two of these patients had peak Doppler gradients early after SAVP of 45 mm Hg, just below the threshold for moderate AS. In all 8 cases, the SAVP included pericardial augmentation or extension of aortic valve leaflets; in 6, SAVP was originally performed for AR resulting from treatment of congenital AS.
Postoperative LV dimensions and function
On early postoperative echocardiography (n = 66), the LVEDD z score was lower than the preoperative z score in all but 4 patients (P < .001). The average postoperative LVEDD z score of 2.1 ± 2.6 was 2.9 ± 2.0 lower than the pre-SAVP z score (P < .001;
Figure 2). Among patients with a pre-SAVP LVEDD z score greater than 4 (n = 45), the LVEDD z score decreased in all but 1; overall, the decrease in LVEDD z score in these patients was greater than in those with less severe dilation (decrease by 3.8 ± 1.8 vs 1.5 ± 1.7, P < .001).
|
Aortic valve reintervention
During a median follow-up of 4.7 years (1 month–17 years), 33 patients underwent 1 or more reinterventions on the aortic valve: repeated SAVP in 3 cases, balloon aortic valvuloplasty in 8, and AVR in 25. This includes 3 patients who underwent early postoperative reintervention—for revision of the valvuloplasty in 2 cases and AVR in 1—because of dehiscence of a created or augmented leaflet. Freedoms from aortic valve reintervention were 91% ± 3% at 1 year, 63% ± 6% at 5 years, and 41% ± 8% at 7.5 years. Factors associated with shorter freedom from aortic valve reintervention according to multivariable Cox regression were the presence of moderate or greater AS at the time of SAVP (5-year freedom from reintervention 33% ± 13% vs 70% ± 7%, P < .001;
Figure 3) and larger pre-SAVP LVEDD z score (P = .05). None of the other factors analyzed were associated with freedom from AVR. Notably, freedom from reintervention did not differ according to age at SAVP, type or cause of AR, technique of SAVP, or moderate AR early after SAVP.
|
A second SAVP for recurrent AR was performed in 3 patients: in the early postoperative period in 2 patients and 3.4 years after SAVP in a patient with truncus arteriosus and a dysplastic aortic valve, whose AR decreased from moderate to mild after repeat SAVP and was unchanged 4.8 years later.
Eight patients (6 with congenital AS and 2 with congenital AR and AS) underwent balloon aortic valve dilatation for AS a median of 5.4 years (0.4–8.3 years) after SAVP, which had included pericardial aortic valve augmentation in 7 patients. Angiographically, the augmented leaflets appeared calcified and immobile in these 7 patients. Balloon dilatation was successful in all cases, reducing the peak AS gradient from a median of 80 mm Hg (55–110 mm Hg) to 40 mm Hg (20–60 mm Hg) without increasing AR to more than mild. An additional balloon dilatation procedure was performed in 3 patients (9–30 months later), with similarly successful results. Three patients (none of whom had a repeated balloon dilatation) subsequently underwent AVR, all within 11 months of balloon dilatation, either for recurrent severe AS (n = 1) or for residual or recurrent moderate AS with LV dysfunction (n = 2). The 5 patients who did not undergo AVR were followed up for 3.9 to 10 years after SAVP and 0.1 to 3.6 years after the most recent balloon valvuloplasty procedure.
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
Nevertheless, the growing body of literature on this topic suggests that SAVP is effective at decreasing AR in the short term and, as we have shown in this study, allows rapid reverse LV remodeling even in patients with severe LV dilation.
Intermediate Outcomes After SAVP in Children and Adolescents with AR
In this series of children and adolescents with moderate or severe AR who underwent SAVP, freedoms from any aortic valve reintervention at 5 and 7.5 years were 63% ± 6% and 41% ± 8%, respectively, and freedoms from AVR at 5 and 7.5 years were 72% ± 6% and 54% ± 9%. Our experience includes many young children, and the durability of repair was just as good in these patients as in older children and adolescents. With regard to intermediate-term aortic valve function, the literature is mixed. Other published studies have demonstrated progressively decreasing freedom from aortic valve reintervention during the several years after SAVP, although the frequency and time course of reintervention vary.9,11,12,14 This series was intended to focus on complex repairs in patients with significant AR and did not include patients with isolated AS, less than moderate AR, or ventricular septal defect–associated AR, for whom the usual techniques of repair have proved durable.12,16
Despite the limited follow-up data on SAVP in children with congenital heart disease and complex AR, more abundant literature concerning the use of pericardial leaflet extension in both children and adults with rheumatic AR and in adults with AR and a structurally normal aortic valve demonstrates that repairs incorporating pericardial augmentation of leaflets can function well for many years.17-20 The optimal approaches to certain technical elements of pericardial leaflet augmentation are not well defined, particularly the duration of pericardial fixation. In patients undergoing AVR after SAVP in our series, the pericardial patches were often heavily calcified and contracted, presumably contributing to progressive post-SAVP aortic valve dysfunction. Our current practice is to fix the pericardium in glutaraldehyde for 5 to 10 minutes, shorter than in our early experience, which leaves the pericardium more pliable; however, the effect of this modification has yet to be determined.
In patients without significant AR after SAVP, LV dimensions and function improved after SAVP and remained stable at follow-up, regardless of pre-SAVP LV size. This is in contrast to the findings of Tafreshi and colleagues,22 who observed that a preoperative LVEDD z score greater than 4 was associated with worse functional outcome and persistent LV dilation after AVR in children and adolescents with AR.21
Postoperative AS After SAVP in Children and Adolescents with AR
One of the potential adverse outcomes of SAVP for AR in patients with congenitally abnormal valves is postoperative AS. This is a particular concern in patients who have AR develop after balloon dilatation for AS. In our experience, 22% of patients had moderate or greater AS in addition to AR before SAVP, and more than half of these had a reduction in AS to mild or less after SAVP, probably in part as a result of reductions in LV volume load and forward stroke volume. Patients with moderate or greater AS had lower aortic annulus z scores than did those with mild or less AS, and there was a trend toward lower aortic annulus z scores among patients whose AS did not improve.
New or increased AS after SAVP was uncommon. Even when significant AS was not present early after SAVP, however, it sometimes developed with time. The cause of this progressive AS was not clear, but all affected patients underwent SAVP with pericardium to repair the aortic valve, and pericardial calcification or contraction may have been a contributing factor, as discussed previously.
A unique feature of this series was the subset of 8 patients who underwent balloon aortic valvuloplasty for AS after SAVP. Most of these patients had AR after previous balloon valvuloplasty for congenital AS, and all had significant AS at the time of SAVP. In all cases, balloon dilatation decreased AS in the acute term. Although 3 of the 8 patients ultimately underwent AVR, the other 5 were alive without AVR as long as 10 years after SAVP. There was no significant increase in AR after balloon dilatation in any of these patients. Accordingly, balloon aortic valvuloplasty may be an effective and safe first-line treatment for patients with AS but minimal AR after SAVP.
Management of AR in Children and Adolescents
Although published reports present guidelines for management of AR in young patients,22 the optimal timing and method of intervention for AR in children remain challenging, and there are limited data to help guide the choice between SAVP and AVR in this patient population. Because serious adverse outcomes were uncommon, our data do not allow inferences that might provide firmer guidance regarding timing and method of intervention in children and adolescents with AR. Of note, age at the time of SAVP was associated neither with worse short- or long-term outcome nor with the duration of freedom from reintervention. Our results do support several important conclusions: there are few short- to intermediate-term drawbacks of SAVP, LV dimensions typically normalize or improve substantially after SAVP even when severe dilation is present, and SAVP allows substantial delay of AVR for most patients, which may facilitate eventual AVR with a larger prosthesis or bioprosthesis. With improved patient selection and surgical techniques, the durability of SAVP should continue to improve.
A common alternative to SAVP in children and adolescents with aortic valve disease is the Ross procedure.4-6,23 In contrast to SAVP, the Ross procedure involves replacement of the entire aortic root, with reimplantation of the coronary arteries, as well as placement of a valved conduit between the right ventricle and pulmonary arteries. Apart from an important incidence of need for conduit replacement, there is increasing evidence of significant progressive neoaortic root dilation and autograft failure.5,23
Limitations
This study is limited by its retrospective nature, by the heterogeneous patient population, and by the fact that referral for surgery was subjective in most cases. Furthermore, this experience encompasses a period when the techniques of SAVP were under development and thus may include a learning curve. Regular serial measurements of post-SAVP LV geometry and function were not available, which limits our insight into the evolution of changes in aortic valve function and LV size and function with time. Although the relative benefits and drawbacks of SAVP relative to therapeutic alternatives, such as mechanical or pulmonary autograft AVR, would be useful, this study does not allow direct comparison between SAVP and AVR.
|
Conclusions |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
|
Figure E1 |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
|
Table E1 Associated cardiovascular anomalies and previous interventions
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
AS, Aortic stenosis.
Table E2 Baseline left ventricular and aortic dimensions and functional parameters
| |||||||||||||||||||||||||||
Adequate data were available for 75 patients unless otherwise specified. LV, left ventricular.
|
Footnotes |
|---|
* Both authors contributed equally to the authorship of this article. 
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionConclusionsFigure E1References |
|---|
This article has been cited by other articles:
|
|
 |
|
  P. O. Myers, V. Bautista-Hernandez, P. J. del Nido, G. R. Marx, J. E. Mayer, F. A. Pigula, and C. W. Baird Surgical repair of truncal valve regurgitation Eur J Cardiothorac Surg, April 26, 2013; (2013) ezt213v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Sinha and R. Jonas Reply to the Editor J. Thorac. Cardiovasc. Surg., July 1, 2012; 144(1): 285 - 286. [Full Text] [PDF]
|
|
|
|
 |
|
 T. Zhao, J. Hu, and Y. Yang Anatomic and Functional Aortic Valvuloplasty for Correction of Aortic Valve Prolapse in Ventricular Septal Defect With Aortic Insufficiency Ann. Thorac. Surg., January 1, 2011; 91(1): 308 - 310. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. O. Myers, C. Tissot, J. T. Christenson, M. Cikirikcioglu, Y. Aggoun, and A. Kalangos Aortic valve repair by cusp extension for rheumatic aortic insufficiency in children: Long-term results and impact of extension material J. Thorac. Cardiovasc. Surg., October 1, 2010; 140(4): 836 - 844. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. C. Polimenakos, S. Sathanandam, C. Blair, C. ElZein, D. Roberson, and M. N. Ilbawi Selective Tricuspidization and Aortic Cusp Extension Valvuloplasty: Outcome Analysis in Infants and Children Ann. Thorac. Surg., September 1, 2010; 90(3): 839 - 847. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. C. Polimenakos, S. Sathanandam, C. ElZein, M. J. Barth, R. S.D. Higgins, and M. N. Ilbawi Aortic cusp extension valvuloplasty with or without tricuspidization in children and adolescents: Long-term results and freedom from aortic valve replacement J. Thorac. Cardiovasc. Surg., April 1, 2010; 139(4): 933 - 941. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Pozzi, A. Quarti, M. Colaneri, A. Oggianu, A. Baldinelli, and P. L. Colonna Valve repair in congenital aortic valve abnormalities Interact CardioVasc Thorac Surg, April 1, 2010; 10(4): 587 - 591. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
