Abstract
Background
Aortic homograft root replacement is an alternative to mechanical aortic valve replacement or a Ross operation for children with aortic valve disease. This study aimed to evaluate the long-term outcomes of aortic homograft root replacement.
Methods
Between 2004 and 2021, 38 children underwent replacement of their aortic valves with an aortic homograft at a single institution. Electronic medical records were reviewed. Survival and reinterventions were the 2 main end points of interest.
Results
The median age and weight were 14 years (interquartile range [IQR], 7-17 years) and 52 kg (IQR, 26-75 kg). Six patients were syndromic (6/38 [16%]), and 4 patients had active endocarditis (4/38 [13%]). Median aortic homograft size implanted was 23 mm in diameter (IQR, 21-24 mm). There was no early mortality and 2 late deaths (5.3%); 8 homografts (21%) were replaced at follow-up with no deaths after replacement of the homograft. Of the 38 implanted homografts, 28 (74%) were functioning well at a median of 81 months after initial implantation. The actuarial reintervention-free survival was 50% at 224 months. The Kaplan-Meier estimated survival at 220 months was 90%.
Conclusions
Replacement of the aortic valve with an aortic homograft is a reasonable valve substitute in children, recognizing that some of these homografts will need to be replaced over time. The risk of reoperation is low, and it can be performed safely.
In Short.
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Aortic homograft is a reasonable option for replacement of aortic valve in children.
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Reintervention-free survival was 50% at 224 months in our cohort.
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The mortality risk of reoperation for homograft failure is low.
The Holy Grail of aortic valve replacement does not exist. Every surgical option for aortic valve disease has a tradeoff that determines its utility in a particular patient.1 In a child or adolescent with a long life expectancy, the burden of living with a replaced valve can be enormous. Whereas every effort is made to repair the aortic valve in children, it is not always possible to accomplish a satisfactory and durable repair. The Ross operation remains our preferred replacement option in children and teens with aortic valve disease not amenable to repair. Barring a much higher operative risk in neonates and infants, the Ross operation is durable with a low risk of reintervention even in the younger patients.2,3 However, there are situations in which the Ross operation is not an option. In such a scenario, we have used aortic allografts to replace the aortic valve as opposed to mechanical or bioprosthetic valves. This report describes our experience with the use of aortic homograft to replace the aortic valve in children.
Patients and Methods
This single-center retrospective study was conducted at a tertiary pediatric cardiac surgical center. Institutional review board approval was obtained with waiver of informed consent. All pediatric patients (<18 years of age) who underwent aortic valve operation with homograft root replacement between 2004 and 2021 were included in this study. Non-homograft aortic valve replacement and aortic valve repairs were excluded. The primary outcomes were reintervention-free survival and overall survival. Other outcomes of interest were postprocedural complications and cardiac complications during the follow-up period. Homograft dysfunction was defined as an echocardiographic mean gradient of >20 mm Hg across the homograft or more than mild insufficiency. Categorical variables were described by proportions and percentages. Continuous variables were described as the median and interquartile range (IQR). Survival estimates were generated with the Kaplan-Meier method. Institutional review board approval was obtained for this study.
Results
Fifty children underwent isolated aortic valve repair/replacement between 2004 and 2021. Thirty-eight patients underwent homograft root replacement and were the participants of this study (Table). The median age and weight were 14 years (IQR, 6-16 years) and 52 kg (IQR, 26-75 kg). Six patients (16%) were syndromic, including Patau, Hunter, and DiGeorge syndromes. Four patients (13%) had active infective endocarditis at the time of aortic homograft implantation. Most of the patients were male (25/38 [66%]), and 58% (22/38) were White. The median aortic homograft size was 23 mm (IQR, 21-24 mm). Bicuspid aortic valve was the most common pathologic process. Most of the patients had predominantly severe aortic regurgitation (30/38 [79%]). Fourteen patients (37%) in the cohort had at least 1 prior cardiac surgical procedure for aortic valve disease. One patient had 2 prior sternotomies and another patient had 3 prior sternotomies before homograft aortic valve replacement. One patient had a prior tetralogy of Fallot repair, another patient had a prior arterial switch operation, 2 had a prosthetic aortic valve replacement, and 2 more had a prior Ross operation before homograft aortic valve replacement. Cardiogenic shock (6/38 [16%]), active infective endocarditis (4/38 [13%]), and nonusable pulmonary valve (prior tetralogy repair, Ross operation, arterial switch operation; 3/36 [8%]) were the primary reasons for homograft implantation. There was no operative mortality. Postoperative complications included cardiac arrest (n = 2) and complete heart block (n = 1). The overall follow-up duration was 81 months (IQR, 28-151 months). Two patients (5.3%) died late after surgery. One patient died of heart failure 5.5 years after the initial operation; another patient died of pneumonia 10 years after the index procedure. Eight patients (21%) underwent reoperations for homograft failure at a median of 92 months (IQR, 86.5-107.5 months) after the initial operation. One of these failures was related to homograft endocarditis (2.6%). None of the other homografts were involved with endocarditis at follow-up. There was no mortality during reoperation. The overall survival and reintervention-free survival are depicted in Figures 1 and 2. At last follow-up, 18 patients (47%) were alive without needing homograft replacement. Of these homografts, 4 are dysfunctional but have not yet been replaced; 14 homografts are functioning well without meeting the criteria for homograft dysfunction.
Table.
Patient characteristics and outcomes
| Variable | Homograft aortic root replacement (N = 38) |
|---|---|
| Age, y | 14 (7.25-16.75) |
| Sex, male | 25/38 (66) |
| No. of previous operations | 2 (1-3) |
| Syndromes | 6/38 (16) |
| Length of stay, d | 3 (2-5) |
| Overall survival | 36/38 (95) |
| Reinterventions for aortic valve | 8/38 (21) |
| Homograft dysfunction | 12/38 (32) |
Continuous variables are presented as median (interquartile range). Categorical variables are presented as proportions (percentage).
Figure 1.
Kaplan-Meier estimate of overall survival after aortic valve replacement with homograft.
Figure 2.
Kaplan-Meier estimate of reintervention for homograft dysfunction after aortic valve replacement with homograft.
Comment
Homografts are an attractive option for aortic valve replacement in children for several reasons. A homograft is technically less complex than a Ross operation while resulting in similar late outcomes. The overall survival is similar between the Ross operation and aortic homografts (96% in each group at 7 years) with a similar rate of reoperation.4 It is also well known that stentless aortic valves show no increase in gradient with exercise, whereas mechanical valves are obstructive when the cardiac output increases during exercise.5 In contrast to mechanical valves, homografts also obviate the need for anticoagulation. The freedom from bleeding/thromboembolic events for homografts has been reported to be 100% at 15 years.6 In contrast, mechanical valves have 3% to 4% incidence of thromboembolic and bleeding complications at 5 years.7 The reoperation rates for homografts are significantly higher compared with mechanical valves, however. A systematic review revealed that reoperation rates were similar for the Ross operation and mechanical valves (1.6% per year and 1.07% per year, respectively) but much higher for homografts (5.44% per year). Nevertheless, the mortality after reoperation for homograft degeneration is extremely low as demonstrated in our series as well as in other publications.8,9 However, there might be morbidity associated with reoperations, and we do not have the data regarding morbidity in our patients who underwent reoperations.
There are few data comparing bioprosthetic valves with homografts in the aortic position in children. Homografts probably have a hemodynamic advantage in comparison to stented bioprostheses, although there is no direct evidence to support this. Structural valve degeneration is the most common cause of reintervention for both homografts and bioprosthetic valves.6,8 Bioprosthetic valves fail earlier in younger patients. There is a 20% incidence of reoperation at 3 years for younger patients with a bioprosthetic aortic valve, with a reintervention-free survival of only 15% at 15 years.6 Our series clearly demonstrates an advantage for homografts in this respect. The reintervention-free survival is 50% at 18 years. Other studies have also shown an advantage for decellularized homografts with reintervention-free survival up to 67% at 10 years.8
Limitations
This is a single-center retrospective study with no control group for comparison. The indications for homograft aortic root replacement were not entirely clear in all patients from retrospective chart review. It was obvious in some patients (endocarditis, prior arterial switch, tetralogy repair, or Ross), whereas in the rest of the patients, the reason for choosing a homograft was not explicitly stated in the records. The small numbers and low event numbers also did not allow us to tease out the risk factors for homograft failure.
Conclusion
Homograft aortic root replacement avoids the complexity of Ross, avoids anticoagulation, does not degenerate at a rate seen with bioprosthetic valves, and provides an effective hemodynamic profile. Homograft aortic root replacement in children is associated with negligible operative mortality and a low risk of complications during the medium-term follow-up. It is a suitable option in this population of patients in whom there is a desire to avoid anticoagulation and when a Ross operation or repair is not an option. The longevity of the homograft varies but will need reintervention during 5 to 15 years after initial implantation. The reoperative mortality for homograft replacement is low, and it can be safely performed.
Acknowledgments
Funding Sources
The authors have no funding sources to disclose.
Disclosures
The authors have no conflicts of interest to disclose.
References
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