ATS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Ann Thorac Surg 2009;88:849-855. doi:10.1016/j.athoracsur.2009.06.003
© 2009 The Society of Thoracic Surgeons
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Eric J. Devaney
Edward L. Bove
Jennifer C. Hirsch
Richard G. Ohye
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Konuma, T.
Right arrow Articles by Ohye, R. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Konuma, T.
Right arrow Articles by Ohye, R. G.
Related Collections
Right arrow Congenital - cyanotic

Original Articles: Pediatric Cardiac

Performance of CryoValve SG Decellularized Pulmonary Allografts Compared With Standard Cryopreserved Allografts

Takeshi Konuma, MD, Eric J. Devaney, MD, Edward L. Bove, MD, Sarah Gelehrter, MD, Jennifer C. Hirsch, MD, Zarry Tavakkol, MD, Richard G. Ohye, MD*

Divisions of Pediatric Cardiovascular Surgery and Pediatric Cardiology, University of Michigan Medical School, Ann Arbor, Michigan

Accepted for publication June 1, 2009.

* Address correspondence to Dr Ohye, 5144 CVC/SPC 5864, 1500 East Medical Center Dr, Ann Arbor, MI 48109 (Email: ohye{at}umich.edu).

Presented at the Fifty-fifth Annual Meeting of the Southern Thoracic Surgical Association, Austin, TX, Nov 5–8, 2008.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 Reference
 
Background: There is no ideal option for pulmonary valve replacement in children. Cryopreserved pulmonary allografts frequently demonstrate early valve regurgitation and may elicit an immune response. To improve these shortcomings, the SynerGraft process (CryoLife, Kennesaw, GA) decellularizes an allograft, leaving only connective tissue, which then becomes repopulated with host cells. A previous study at our institution demonstrated superior short-term durability of the SynerGraft-processed CryoValve SG compared with standard allografts. Longer-term impact of the technology remains unknown.

Methods: A single institution review was performed of all CryoValve SGs implanted between 2001 and 2004. Forty-one CryoValve SG patients and 41 age and diagnosis-matched standard allograft controls were evaluated. Demographics, survival, reintervention, and echocardiographic findings were analyzed.

Results: There were no significant differences between groups in demographics, valve diameter, orthotopic-heterotopic allograft position, or follow-up. For the entire cohort, there was no difference in early or late insufficiency or stenosis at a mean follow-up of 46 ± 14 months. However, freedom from moderate to severe insufficiency (>3+) was significantly better for CryoValve SG patients (p = 0.05). In addition, for patients greater than 2 years of age, CryoValve SGs were significantly less regurgitant (p = 0.045) and stenotic (p = 0.041). Long-term survival was identical at 85% (35 of 41).

Conclusions: When compared with standard allografts, CryoValve SGs demonstrate superior freedom from significant insufficiency at intermediate follow-up. In older children, CryoValve SGs display less insufficiency and stenosis. For infants, patient age, valve diameter, previous conduit, and rapid somatic growth would likely be the predominant factors leading to allograft failure.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 Reference
 
There is no ideal option for pulmonary valve replacement in children. Cryopreserved pulmonary allografts are recognized as the standard for reconstruction of the right ventricular outflow tract. However, freedom from structural degeneration is variable and occurs more frequently and earlier after valve transplantation in younger recipients [1]. Most patients transplanted with an allograft valve develop humoral antibodies against human leukocyte antigen (HLA) that are specific to the transplanted tissue [2], and host antigen recognition and antibody development may be linked to early onset tissue calcification and structural valve deterioration [3, 4]. To improve these shortcomings, the SynerGraft (CryoLife, Kennesaw, GA) process decellularizes an allograft, leaving only connective tissue, which then becomes repopulated with host cells.

The CryoValve SG (CryoLife) allografts still have the advantage of the lack of the need for anticoagulation and of excellent handling characteristics, and may have lower antigenicity and greater durability long term than standard pulmonary allografts. A previous study at our Institution demonstrated superior short-term durability of the SynerGraft-processed CryoValve SGs compared with standard allografts [5]. There are few reports about the longevity of CryoValve SG allografts especially for children, and longer term impact of the technology remains unknown.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 Discussion
 Acknowledgments
 References
 Reference
 
Study Population
Between June 2001 to July 2004, 41 patients were implanted with CryoValve SG pulmonary valves (CryoLife Inc) as a valved conduit for a Rastelli or Ross procedure at the C. S. Mott Children's Hospital of the University of Michigan. We excluded patients who received SynerGraft-treated pulmonary arteries as patch material. Forty-one contemporary controls were selected, who received standard cryopreserved pulmonary allografts during the same time period. This retrospective study was performed after the Institutional Review Board approval was obtained.

Data Acquisition
Controls were cases matched by age first, and then diagnosis in an attempt to achieve a cohort similar in immunologic maturity, allograft diameter, and prognosis. Functional and morphologic indices were collected through institutional medical reports, including gender, age, height, weight, pulmonary allograft size, patient factors (allograft position, previous valve replacement), and operative procedure. Other factors that were reviewed included length of follow-up, valve function immediately after the operation and at the time of the last follow-up, as well as postoperative complications and mortality. No histologic evaluations of explanted allografts were available in this retrospective study.

In cases where the actual echocardiogram was available, valve function was evaluated by a single echocardiographer, who was blinded to the type of valve. In the remaining 10 cases, the echocardiogram reports were utilized. The degree of pulmonary stenosis was recorded by measurement of Doppler peak instantaneous gradient. Pulmonary insufficiency grades were assigned according to the standard subjective scale of 0 to 4 (none = 0, trivial = 1, mild = 2, moderate = 3, severe = 4).

Statistical Analysis
Normally distributed data are expressed as mean ± SD and non-normal data as median (range). Continuous variables, such as valve gradient, were compared using the unpaired Student t test. Categoric data, such as degree of pulmonary insufficiency, are given as total numbers and relative frequencies were compared using the Mann-Whitney U test. Analysis of variance techniques were used to analyze the risk factor of graft failure between CryoValve SG and standard allografts. Correlations were assessed using the Pearson correlation coefficient for normally distributed, continuous variables. Non-normal continuous variables were assessed using the Spearman correlation coefficient by rank. The Kaplan-Meier method was applied to estimate the actuarial survival and freedom from reintervention, and significance was assessed by the log-rank test. A p value less than 0.05 was considered to indicate statistical significance. Statistical analysis was performed using the StatView 5.0 software package (SAS Institute Inc, Cary, NC).


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 Discussion
 Acknowledgments
 References
 Reference
 
Demographics
There were no significant differences in age, weight, valve diameter, orthotopic versus heterotopic valve position, or follow-up period from date of implantation of CryoValve SG allografts and standard allografts (Table 1; Fig 1).


View this table:
[in this window]
[in a new window]

  		Table 1 Demographic and Conduit Data
 

Figure 1
View larger version (21K):
[in this window]
[in a new window]

  		Fig 1. Distribution of implanted allograft diameters. ({blacksquare} = CryoValve SG; {square} = standard allograft.)

 
Time-related Hemodynamic Performance
Conduit valve stenosis
Discharge echocardiographic data showed an overall low pressure gradient across the valve and no significant differences between the two groups, with the CryoValve SG allografts and standard allograft demonstrating a mean pressure gradient of 2.7 ± 6.0 mm Hg and 0.8 ± 2.5 mm Hg, respectively (p = 0.14) (Table 2). Echocardiographic data at follow-up showed an increase in peak instantaneous gradient to 19.3 ± 15.6 mm Hg (CryoValve SG) and 28.1 ± 26.7 mm Hg (standard allograft). While there was a higher mean gradient in the standard group, the sample size was too limited to be able to detect significance (p = 0.14).


View this table:
[in this window]
[in a new window]

  		Table 2 Degree of Valve Stenosis and Insufficiency at Discharge and at Last Follow-Up
 
Conduit valve regurgitation
Median echocardiographic grade of conduit regurgitation at discharge was also similar for the CryoValve SGs (+1; range, 0 to +2) and standard allografts (0; range, 0 to +2; p = 0.42) (Table 3). Although the insufficiency at follow-up progressed in both groups, the median degree of insufficiency of the CryoValve SGs (+2; ranges 0 to +4) was less than that of standard grafts (+3; ranges 0 to +4, p = 0.068). However, while the median degree of insufficiency of any severity fell just short of statistical significance, clinically significant insufficiency (≥3+) was more common in the patients receiving standard allografts (p = 0.05) (Fig 2).


View this table:
[in this window]
[in a new window]

  		Table 3 Degree of Valve Stenosis and Insufficiency at Discharge and at Last Follow-Up by Age Group
 

Figure 2
View larger version (10K):
[in this window]
[in a new window]

  		Fig 2. Actuarial freedom from 3+ or greater insufficiency. (SG = CryoValve SG; SA = standard allograft.)

 
Transcatheter or Surgical Reintervention to Conduit
Indication for reintervention
Transcatheter intervention for conduit stenosis was performed in one standard allograft patient 67 months postimplantation. Ten patients underwent surgical reintervention for conduit replacement. Three of the 10 patients requiring reintervention were in the CryoValve SG group. The indication for conduit replacement was conduit stenosis in two patients (peak gradient 60 mm Hg and 24 mm Hg). The third patient underwent branch pulmonary artery angioplasty and conduit upsizing, although the conduit did not have stenosis (peak gradient 0 mm Hg) and the degree of insufficiency was 1+ at the time of the procedure. Seven patients required reintervention in the standard allograft group. The indication for operation were conduit stenosis (n = 2; peak gradient 60 mm Hg and 75 mm Hg), conduit upsizing without significant gradient or insufficiency (n = 2), and free pulmonary valve insufficiency (n = 2).

Freedom from reintervention
The number of interventions were not different between patients who received CryoValve SGs or standard allografts (7.3% [3 of 41] versus 19.5% [8 of 41], respectively; p = 0.10). The freedom from reintervention at five years was CryoValve SGs 86% and standard allograft 76%. While the data suggest a trend toward a greater freedom from reintervention, the sample size was not sufficient to demonstrate a statistically significant difference (log-rank test; p = 0.29) (Fig 3).


Figure 3
View larger version (11K):
[in this window]
[in a new window]

  		Fig 3. Actuarial freedom from reintervention (Kaplan-Meier).

 
Survival
The Kaplan-Meier-estimated overall survival ratio after surgery was identical between the CryoValve SGs patients and the standard allograft patients (Fig 4). Of the CryoValve SG patients, there were 4 hospital deaths and 2 late deaths. In the standard allograft cohort, there were 3 hospital deaths and 3 late deaths. No deaths were related to conduit dysfunction.


Figure 4
View larger version (9K):
[in this window]
[in a new window]

  		Fig 4. Long-term survival. (SG = CryoValve SG; SA = standard allograft.)

 
Comparison by Age Group
The overall cohort was then divided into an early age group (<2 years of age) and a late age (≥2 years of age) group according to the age at the time of the implant. The data comparing the peak gradient and degree of stenosis at last follow-up between age groups are summarized in Table 3. In patients less than 2 years of age, stenosis and insufficiency at follow-up of the two types of allograft were similar. However, in the older age group, the CryoValve SG patients had both lower peak gradients across the valve (p = 0.045) and a lower degree of insufficiency (p = 0.041). The Kaplan-Meier estimates for freedom from reintervention for the two age groups (Fig 5) do not demonstrate a statistically significant difference (p = 0.08).


Figure 5
View larger version (11K):
[in this window]
[in a new window]

  		Fig 5. Overall freedom from reintervention by age group (Kaplan-Meier).

 
Risk Factor Analysis
For all patients (both CryoValve and standard valve), multivariate analysis revealed weight (p = 0.04), graft size (Fig 6; p = 0.0003), and the presence of a previous conduit (CryoValve SG cohort- allograft 7, heterograft 2, unknown 1; standard cohort- allograft 9, heterograft 4, p = 0.0046) as significant factors for the development of insufficiency. Conversely, no factors in the model could be shown to have a significant relationship to the degree of stenosis (Table 4).


Figure 6
View larger version (8K):
[in this window]
[in a new window]

  		Fig 6. Relation between valve size and insufficiency. ({diamondsuit} = CryoValve SG; {blacksquare} = standard allograft.)

 

View this table:
[in this window]
[in a new window]

  		Table 4 Covariant Analysis of Risk Factors for Stenosis or Insufficiency
 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
Discussion
 Acknowledgments
 References
 Reference
 
Characteristics of an ideal pulmonary valve replacement for children are long durability, lack of need for anticoagulation, low antigenicity, ability to grow, ready availability, favorable handling, and ease of implantation. Valved pulmonary allografts were initially introduced in 1966 by Ross and Somerville [6], and are one of the preferred materials for cardiac surgery in both adult and children. They have shown clinical durability particularly in adults [7–10]. Although they tend to be relatively resistant to degenerative conduit stenosis and valve regurgitation compared to xenografts, deterioration and requirement of replacement of conduit is inevitable, particularly in the pediatric population [11–13]. In addition, there is growing concern over donor-specific cellular responses and elevated levels of tissue-specific antibodies found in allograft valve recipients, as host antigen recognition and antibody development may be linked to early onset tissue calcification and structural valve deterioration [3, 14]. In addition, the high panel reactive antibody (PRA) levels decrease the number of potential donors for those patients who progress to a need for transplantation. Vogt and colleagues [15] identified cellular rejection in the wall of allograft material explanted from the right ventricular outflow tract of children. These inflammatory cells were predominantly T lymphocytes. Rajani and colleagues [4] similarly demonstrated histologic evidence of rejection in five allograft valves removed from infants. A similar response has not been documented in allografts explanted from adults, where explanted tissue displays a picture more consistent with coronary arteries in transplant-associated vascular disease. Shaddy and colleagues [16] prospectively measured the frequency of human leukocyte antigen (HLA) class I PRA in children undergoing open heart surgery with or without the implantation of allograft material. They found that in patients receiving an allograft, the PRA increased within three months of surgery, while the control group had no significant change in PRA. This immune response is believed to have been a contributory factor in the early degradation of allograft function in some patients.

To reduce antigenicity, SynerGraft technology was developed as a decellularization process for allograft tissue. SynerGraft methods result in native cell removal from the collagen tissue matrix. Removal of cellular material may reduce or eliminate the immunologic response and leave a functional vascular matrix that is available for autogenous remodeling. Migration of the recipient-specific cells into the matrix eventually renders the graft indistinguishable from other endogenous tissues [17], and demonstrated the preservation of tissue strength, biomechanics, and valvar hydrodynamic function [14]. Before clinical implantation, O'Brien and colleagues [18] and Elkins and colleagues [19] reported experimental results from the implantation of decellularized porcine valves into the right ventricular outflow tract of sheep. After 4 to 6 months, histologic assessment showed progressive recellularization of the conduit and valve leaflets with host fibroblastoid cells and subsequently with mature interstitial cells without evidence of calcification.

Elkins and colleagues [14] reported the humoral immune response to decellularized allografts in human subjects. They implanted SynerGraft-treated valves in 66 patients with a median age of 34 years (range, 3 months to 59 years). Eight-six percent (57 of 66) of patients had a negative PRA prior to implantation, and 51 of 66 (77%) continued to have a negative PRA at three months after surgery. Of the eleven pediatric patients (age 3 months to 16 years), all were PRA negative preoperatively and remained negative postoperatively. Hawkins and colleagues [2] also evaluated the immune response to CryoValve SGs and showed significantly lower levels of class I and class II HLA antibody formation at 1, 3, and 12 months after implantation compared with standard cryopreserved allografts. Early hemodynamic function of decellularized grafts was similar to that of standard cryopreserved allograft valves. Zehr and colleagues [20] also showed lack of immune reaction to CryoValve SG aortic valve conduits in 22 adult patients.

There are some histologic examinations of SynerGraft-treated tissue in the literature [21, 22]. One patient was five weeks postimplantation and the other was two years postimplantation. In both cases the SynerGraft-treated tissue was entirely devoid of nuclei, with the exception of a neointimal layer and focal cellular incursions into the superficial elastic media. The remainder of the graft tissue was free of inflammation.

Bechtel [23] evaluated twenty-two patients, who had received a CryoValve SG, by echocardiography and computed tomography angiographic (CTA) and compared the findings with conventional cryopreserved allografts (median follow-up 32 months). Neither the pressure gradients across the allograft, nor the effective orifice area differed between the groups (p = 0.96).

It has been suggested that allografts placed in an orthotopic position may have greater durability due to laminar flow and lack of sternal compression of the conduit. In our study, the CryoValve SG group had a greater number of allografts placed in a heterotopic position compared with standard grafts, a difference that almost reached statistical significance (p = 0.06). Hence, the results for durability of the CryoValve SG may be biased so as to disadvantage this cohort compared with the standard allograft group. Thus, the trends toward less stenosis and insufficiency in the overall cohort and the statistically significant difference in the older (≥2 years) age group, may have been stronger, if the groups were able to be better matched. However, the fact that there were no differences between groups with regard to stenosis or insufficiency at the time of discharge suggests that position did not adversely affect the allografts.

A previous report [5] from our center demonstrated the superior short-term durability of the CryoValve SGs compared with standard allografts with respect to both stenosis and insufficiency. At longer follow-up, there were no significant differences between CryoValve SGs compared with standard allografts in conduit stenosis and valve insufficiency, although overall degree of insufficiency had a trend favoring the CryoValve SG (p = 0.068). However, when analyzing the incidence of clinically important (≥3+) insufficiency, there was a statistically significant advantage for the CryoValve SG.

Actuarial freedom from reintervention was not significantly different between groups. It may initially seem incongruous that there should be significantly less insufficiency, yet equal rates of reintervention. However, the majority of reinterventions in this trial and in clinical practice are for the development of stenosis, as pulmonary regurgitation is generally well tolerated for a longer period of time. The closer relationship of the need for reintervention and stenosis would likely explain why the degree of significant insufficiency can be lower in the CryoValve SG group, while the rate of reintervention is equivalent.

The current cohort was also analyzed by age less than 2 years and age 2 years or greater. The hypotheses being that any benefit of enhanced durability in the CryoValve SG group would be less likely to be detected in patients less than 2 years of age due to the rapid somatic growth of these younger children, and the early need to replace the conduit is primarily due to patient growth rather than allograft failure. This hypothesis is supported by the Kaplan-Meier estimates for freedom from reintervention for the two age groups (Fig 5), which while not showing a statistically significant difference (p = 0.08), do show the time-related nature of the need for reintervention. Findings in the older age cohort did demonstrate significantly lower gradients and insufficiency in those patients receiving a CryoValve SG.

Previous studies have suggested that risk factors for allograft failure include younger recipient, previous xenograft valve [1], lower age, low operative weight, small graft size [11], reoperation, and age at operation [12]. Similarly in our study, patient age, valve diameter, and previous conduit were risk factors for the development of insufficiency, and these might suggest younger patients have stronger immune response and a previous conduit might enhance the immune system. Further examination of histology and HLA antibody levels may help define the role of the immune system in valve failure.

It is difficult to make concrete recommendations for which patients may benefit from the use of the CryoValve SG over standard allografts based upon these data. However, from these results one might infer that there may be certain patients who theoretically would benefit from this technology. Statistically significant differences were detected for both the degree of insufficiency and the peak transvalvar gradient in the older age group.

However, the rates of reintervention were unchanged. It is possible that even older groups of patients who could not be tested in this young cohort would benefit even more, as they would not develop the stenosis associated with somatic growth, have a different immunologic milieu, and a less active calcium metabolism. It is also possible that all pediatric patients may derive future benefits from the decreased degree of insufficiency in terms of issues like long-term ventricular function that are beyond the scope of this study. Certain subpopulations of patients, such as those with pulmonary artery hypertension, hypoplastic pulmonary arteries, or tetralogy of Fallot with absent pulmonary valve, may also benefit from the greater resistance of the CryoValve SG to the development of insufficiency. Lastly, the group of congenital heart disease patients who ultimately will require transplantation would greatly benefit from the decrease in PRA associated with SynerGraft-treated allograft tissue.


   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
Acknowledgments
 References
 Reference
 
DR JOSEPH FORBESS (Dallas, TX): I would like to congratulate Dr Devaney and colleagues from the University of Michigan on this retrospective case-controlled study, which is essentially a re-evaluation and expansion of some patients that they reported on in a 2005 Annals of Thoracic Surgery paper [1] in which they compared 26 SynerGraft patients and 26 case controls. That study found decreased regurgitation and stenosis in the SynerGraft patients and no real change in reintervention rate, though the number of reinterventions was very small. That study had 19 months of follow-up. If I am to understand correctly, this is a continuation of an evaluation of that study population, and now you have 41 patients in each group with a mean follow-up of 46 months. You describe no significant difference in the rate of stenosis and regurgitation, but the freedom from moderate and severe regurgitation appears to be improved in the SynerGraft patients. I have several questions.

First, were your echocardiographers blinded? Next, did CryoLife obtain any of these homografts, after you explanted them, to see if their proposed mechanism for improved function and (or) durability is actually true? And thirdly, what is your conduit of choice at this time for neonates, toddlers, and older school age children?

Thank you.

DR DEVANEY: Thank you, Dr Forbess. I appreciate your insightful questions. To answer your first question about the echocardiography, yes, our pediatric cardiologists were blinded with respect to the type of allograft that was implanted. As far as the histologic analysis, I think this would be a great study to undertake in the future. Clearly, most of these patients are ultimately going to need to have conduit replacement. So I think it would be very important to establish the host recellularization phenomenon and see whether that is something that is real or not, and I think that is something that we should discuss either with the CryoLife company or without them. I think it is something that is worth pursuing.

And then finally, what is our conduit of choice? I hesitate to speak for all of my colleagues, but I think it depends on a number of factors. Obviously we like to use a conduit that is easy to handle, and I would say the handling properties of the bovine jugular conduit are fairly similar to that of the pulmonary allograft. I think that one advantage of the bovine jugular conduit is availability in all sizes. So right now I think we are sort of split as to what our preferred conduit is. I think we would like to see these SynerGrafts become established as something that is an improvement on what we have already. I would consider at least at this point, based on the data that we have and our experience, that I would sort of equate the standard allograft as being fairly equivalent in function and durability to the bovine jugular conduit, and I think the jury is still out on the SynerGraft, but we are hopeful.

DR FORBESS: I meant to mention earlier that at Children's Medical Center in Dallas we have now put in over 70 of those Contegras that you referred to and have really been impressed with the competence of the valve vis-a-vis those of homografts, and we don't have an experience with the SynerGrafts. We have only had one failure from regurgitation in a patient who really was born with no true pulmonary arteries and had a very high distal resistance, and one stenotic failure that was actually torqued at the time of the operation. We have been following them along fairly closely in an IRB [Institutional Review Board]-approved study and have been extremely impressed that at least with regard to valvar competence, it is superior in this size range that you are referring to here, in the 18 mm or so. The homograft has essentially gone away in our particular practice.

Thank you.


   Acknowledgments
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
References
 Reference
 
Funding was received from CryoLife (Kennesaw, GA) in support of this research project.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
Reference
 

  1. Yacoub M, Rasmi NR, Sundt TM, et al. Fourteen-year experience with homovital homografts for aortic valve replacement J Thorac Cardiovasc Surg 1995;110:186-194.[Abstract/Free Full Text]
  2. Hawkins JA, Hillman ND, Lambert LM, et al. Immunogenicity of decellularized cryopreserved allografts in pediatric cardiac surgery: comparison with standard cryopreserved allografts J Thorac Cardiovasc Surg 2003;126:247-253.[Abstract/Free Full Text]
  3. Yankah AC, Alexi-Meskhishvili V, Weng Y, Schorn K, Lange PE, Hetzer R. Accelerated degeneration of allografts in the first two years of life Ann Thorac Surg 1995;60:S71-S77.[Medline]
  4. Rajani B, Mee RB, Ratliff NB. Evidence for rejection of homograft cardiac valves in infants J Thorac Cardiovasc Surg 1998;115:111-117.[Abstract/Free Full Text]
  5. Tavakkol Z, Gelehrter S, Goldberg CS, Bove EL, Devaney EJ, Ohye RG. Superior durability of SynerGraft pulmonary allografts compared with standard cryopreserved allografts Ann Thorac Surg 2005;80:1610-1614.[Abstract/Free Full Text]
  6. Ross DN, Somerville J. Correction of pulmonary atresia with a homograft aortic valve Lancet 1966;2:1446-1447.[Medline]
  7. O'Brien MF, Stafford EG, Gardner MAH, et al. Allograft aortic valve replacement: long-term follow-up Ann Thorac Surg 1995;60:S65-S70.[Medline]
  8. Doty JR, Salazar JD, Liddicoat JR, Flores JH, Doty DB. Aortic valve replacement with cryopreserved aortic allograft: ten-year experience J Thorac Cardiovasc Surg 1998;115:371-380.[Abstract/Free Full Text]
  9. Albert JD, Bishop DA, Fullerton DA, et al. Conduit reconstruction of the right ventricular outflow tract. Lessons learned in a 12 year experience. J Thorac Cardiovasc Surg 1993;106:228-235.[Abstract]
  10. Bull C, Macartney FJ, Horvath P, et al. Evaluation of long-term results of homograft and heterograft valves in extracardiac conduits J Thorac Cardiovasc Surg 1987;94:12-19.[Abstract]
  11. Baskett RJ, Ross DB, Nanton MA, Murphy DA. Factors in the early failure of cryopreserved homograft pulmonary valves in children: preserved immunogenicity J Thorac Cardiovasc Surg 1996;112:1170-1179.[Abstract/Free Full Text]
  12. Stark J, Bull C, Stajevic M, Jothi M, Elliot M, de Leval M. Fate of subpulmonary homograft conduits: determinants of late homograft failure J Thorac Cardiovasc Surg 1998;115:506-516.[Abstract/Free Full Text]
  13. Niwaya K, Knott-Craig CJ, Lane MM, Chandrasekaren K, Overholt ED, Elkins RC. Cryopreserved homograft valves in the pulmonary position: risk analysis for intermediate-term failure J Thorac Cardiovasc Surg 1999;117:141-147.[Abstract/Free Full Text]
  14. Elkins RC, Dawson PE, Goldstein S, Walsh SP, Black KS. Decellularized human valve allografts Ann Thorac Surg 2001;71(5 suppl):S428-S432.[Medline]
  15. Vogt PR, Stallmach T, Niederhäuser U, et al. Explanted cryopreserved allografts: a morphological and immunohistochemical comparison between arterial allografts and allograft heart valves from infants and adults Eur J Cardiothorac Surg 1999;15:639-645.[Abstract/Free Full Text]
  16. Shaddy RE, Hunter DD, Osborn KA, et al. Prospective analysis of HLA immunogenicity of cryopreserved valved allografts used in pediatric heart surgery Circulation 1996;94:1063-1067.[Abstract/Free Full Text]
  17. Clarke DR, Lust RM, Sun YS, Black KS, Ollerenshaw JD. Transformation of nonvascular acellular tissue matrices into durable vascular conduits Ann Thorac Surg 2001;71(5 suppl):S433-S436.[Medline]
  18. O'Brien MF, Goldstein S, Walsh S, Black KS, Elkins R, Clarke D. The SynerGraft valve: a new acellular (nonglutaraldehyde- fixed) tissue heart valve for autologous recellularization first experimental studies before clinical implantation Semin Thorac Cardiovasc Surg 1999;11(4 suppl 1):194-200.[Medline]
  19. Elkins RC, Goldstein S, Hewitt CW, et al. Recellularization of heart valve grafts by a process of adaptive remodeling Semin Thorac Cardiovasc Surg 2001;13(4 suppl 1):87-92.[Medline]
  20. Zehr KJ, Yagubyan M, Connolly HM, Nelson SM, Schaff HV. Aortic root replacement with a novel decellularized cryopreserved aortic homograft: postoperative immunoreactivity and early results J Thorac Cardiovasc Surg 2005;130:1010-1015.[Abstract/Free Full Text]
  21. Miller DV, Edwards WD, Zehr KJ. Endothelial and smooth muscle cell populations in a decellularized cryopreserved aortic homograft (SynerGraft) 2 years after implantation J Thorac Cardiovasc Surg 2006;132:175-176.[Free Full Text]
  22. Sayk F, Bos I, Schubert U, Wedel T, Sievers HH. Histopathologic findings in a novel decellularized pulmonary homograft: an autopsy study Ann Thorac Surg 2005;79:1755-1758.[Abstract/Free Full Text]
  23. Bechtel JF, Gellissen J, Erasmi AW, et al. Mid-term findings on echocardiography and computed tomography after RVOT-reconstruction: comparison of decellularized (SynerGraft) and conventional allografts Eur J Cardiothorac Surg 2005;27:410-415.[Abstract/Free Full Text]

   Reference
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 Reference
 

1. Tavakkol Z, Gelehrter S, Goldberg CS, Bove EL, Devaney EJ, Ohye RG. Superior durability of Synergraft pulmonary allografts compared with standard cryopreserved allografts Ann Thorac Surg 2005;80:1610-1614.[Abstract/Free Full Text]




This article has been cited by other articles:


Home page
 Eur J Cardiothorac SurgHome page
G. Perri, A. Polito, C. Esposito, S. B. Albanese, P. Francalanci, G. Pongiglione, and A. Carotti
Early and late failure of tissue-engineered pulmonary valve conduits used for right ventricular outflow tract reconstruction in patients with congenital heart disease
Eur J Cardiothorac Surg, January 4, 2012; (2012) ezr221v1.
[Abstract] [Full Text] [PDF]

Home page
 CirculationHome page
S. Cebotari, I. Tudorache, A. Ciubotaru, D. Boethig, S. Sarikouch, A. Goerler, A. Lichtenberg, E. Cheptanaru, S. Barnaciuc, A. Cazacu, et al.
Use of Fresh Decellularized Allografts for Pulmonary Valve Replacement May Reduce the Reoperation Rate in Children and Young Adults: Early Report
Circulation, September 13, 2011; 124(11_suppl_1): S115 - S123.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
J. W. Brown, M. Ruzmetov, O. Eltayeb, M. D. Rodefeld, and M. W. Turrentine
Performance of SynerGraft Decellularized Pulmonary Homograft in Patients Undergoing a Ross Procedure
Ann. Thorac. Surg., February 1, 2011; 91(2): 416 - 423.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
R. Zubairi, S. Malik, R. D. B. Jaquiss, M. Imamura, J. Gossett, and W. R. Morrow
Risk Factors for Prosthesis Failure in Pulmonary Valve Replacement
Ann. Thorac. Surg., February 1, 2011; 91(2): 561 - 565.
[Abstract] [Full Text] [PDF]

Home page
 Ann. Thorac. Surg.Home page
P. T. Burch, A. K. Kaza, L. M. Lambert, R. Holubkov, R. E. Shaddy, and J. A. Hawkins
Clinical Performance of Decellularized Cryopreserved Valved Allografts Compared With Standard Allografts in the Right Ventricular Outflow Tract
Ann. Thorac. Surg., October 1, 2010; 90(4): 1301 - 1306.
[Abstract] [Full Text] [PDF]

Home page
 Eur J Cardiothorac SurgHome page
A. Ruffer, A. Purbojo, I. Cicha, M. Glockler, S. Potapov, S. Dittrich, and R. A. Cesnjevar
Early failure of xenogenous de-cellularised pulmonary valve conduits -- a word of caution!
Eur J Cardiothorac Surg, July 1, 2010; 38(1): 78 - 85.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Personal Folders
Right arrow Download to citation manager
Right arrow Author home page(s):
Eric J. Devaney
Edward L. Bove
Jennifer C. Hirsch
Richard G. Ohye
Right arrow Permission Requests
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Konuma, T.
Right arrow Articles by Ohye, R. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Konuma, T.
Right arrow Articles by Ohye, R. G.
Related Collections
Right arrow Congenital - cyanotic

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