Anti-HLA class I antibodies and pulmonary homograft function after the Ross procedure

Pulmonary homograft dysfunction after the Ross procedure using decellularized homografts-a multicenter study

OBJECTIVES

Pulmonary homograft dysfunction is a limitation after the Ross procedure. Decellularized pulmonary homografts can potentially mitigate this complication. The aim of this study was to examine the incidence, predictors, progression, and morphology of pulmonary homograft dysfunction using data from the Canadian Ross Registry.

METHODS

From 2011 to 2019, 466 consecutive patients (mean age: 47 ± 12 years, 73% male) underwent a Ross procedure using a decellularized cryopreserved pulmonary homograft (SynerGraft SG; CryoKife, Kennesaw, Ga). Pulmonary homograft dysfunction was defined as any of the following: peak pulmonary gradient ≥30 mm Hg, pulmonary regurgitation >2, or pulmonary homograft reintervention. Patients meeting ≥1 of these criteria (n = 30) were compared with the rest of the cohort (n = 436). Median follow-up is 2.2 years (maximum = 8.5 years) and 99% complete (1176 patient-years).

RESULTS

The cumulative incidence of pulmonary homograft dysfunction was 11 ± 2% at 6 years. Pulmonary homograft stenosis was the most frequent presentation (n = 28 patients, 93%). Morphologically, stenosis occurred most often along the conduit (59%). Overall, 4 patients required homograft reintervention. At 6 years, the cumulative incidence of homograft reintervention was 3 ± 1%. The instantaneous risk was greatest in the first year after surgery (3.5%/year) and decreased to <1%/year thereafter. Patient age <45 years was the only independent risk factor associated with pulmonary homograft dysfunction (hazard ratio, 3.1, 95% confidence interval, 1.1-8.6, P = .03).

CONCLUSIONS

The use of decellularized cryopreserved pulmonary homografts results in a low incidence of dysfunction and reintervention after the Ross procedure. The risk is greater in the first postoperative year. Younger age is the only independent risk factor for pulmonary homograft dysfunction.

New approach to reduce allograft tissue immunogenicity. Experimental data

OBJECTIVES

Rejection is thought to contribute to the degeneration of valved allografts. Most proposed methods of decellularisation allow usage of treated valves in pulmonic position. We developed a new protocol of devitalization, which provides cell death and suppression of calcification using digitonin and ethylenediaminetetraacetic acid. The aim of the study was to evaluate new allografts in a chronic canine model.

METHODS

Two groups of adult mongrel dogs (5 in each) were used for allograft implantation. The cryopreserved viable (group 1) and devitalized (group 2) heart valve aorta allografts were tested. Allografts were implanted as valved patches into the thoracic aorta and explanted after four months. Histologic examination and fluorescence microscopy were used to test tissue matrix and cells in allografts. Mineralized calcium in the samples was detected using absorption spectroscopy.

RESULTS

The fluorescence microscopy proved that a significant number of cells were viable in the allografts after their cryopreservation (group 1) and all the cells were dead after anticalcinosis devitalisation (group 2). No damage of tissue matrix was observed in group 2 after devitalisation. After explantation, the cusps in both groups were either stuck to aorta wall of the allografts, or there were thrombus clots between the cusps and the wall. Internal surface was covered with neointima. Media of aortic wall was acellular. Repopulation of the viable and devitalized tissues with recipient cells during a 4-month follow-up period was not observed. In non-treated allografts, aortic walls had areas of dissection and infiltration of lymphoid cells. Devitalized patches were homogenous without dissection areas. There was no immune-cell infiltration in devitalized matrix as opposed to cryopreserved vital tissue.

CONCLUSIONS

The new devitalizing technology seems effective in decreasing immune response to homologous tissue. It does not affect elasto-mechanic properties and collagenous structure of allografts. The presented data stimulate interest to the anticalcinosis devitalisation technology as an affective tool for improving biocompatibility of allografts.

Aortic root replacement with a novel decellularized cryopreserved aortic homograft: Postoperative immunoreactivity and early results

OBJECTIVE

Novel antigen-reduction SynerGraft technology (CryoLife Inc, Kennesaw, Ga) reduces the cellular components of a cadaver homograft with an enzymatic and washing process, leaving the extracellular matrix intact. We report the immunoreactivity (positive panel reactive antibody assay) and early operative results of the CryoLife SynerGraft aortic valve conduit homograft.

METHODS

Twenty-two patients (age 53 +/- 14 years, range 31-80 years) from April 2002 to July 2003 underwent aortic root replacement with a CryoLife SynerGraft aortic valve conduit homograft (CryoLife Inc, Kennesaw, Ga) for congenital or acquired aortic valve disease, aortic aneurysm with aortic valve disease, or native or prosthetic aortic valve endocarditis. Baseline percentage positive panel reactive antibody results were negative (<10%) for all and were assessed at 1 month, 3 months, and 1-year. Homograft function was evaluated by echocardiography.

RESULTS

Early mortality was 0%. Two late deaths at 1 postoperative year were unrelated to homograft function. At 1 postoperative month, panel reactive antibody results were negative in 20 patients (91%). At 3 months, 19 of 22 patients (86%) had negative results, including 1 with previous positive results. At 1 year, 19 of 20 patients (95%) had negative results, including 2 of the 3 with previous positive results. The mean aortic valve gradients were 12 +/- 8 mm Hg (n = 21) at discharge and 11 +/- 7 mm Hg (n = 18) at 1 year. At a mean follow-up of 30.3 +/- 5.2 months, the mean gradient was 8.8 +/- 6.3 mm Hg.

CONCLUSION

The SynerGraft decellularization technology successfully removed antigens from an aortic valve homograft conduit. Aortic root reconstruction with the CryoLife SynerGraft aortic valve homograft resulted in low transvalvular gradients, similar to those seen with standard cryopreserved homografts. These early results suggest an advancement in homograft technology. The low panel reactive antibody response may enhance durability by eliminating immune complex-mediated reaction against the homograft. The lack of allosensitization in patients who may require organ transplantation in the future is an added benefit.

Six-year monitoring of the donor-specific immune response to cryopreserved aortic allograft valves: Implications with valve dysfunction

BACKGROUND

The immune rejection has been anticipated as one of the major causes of allograft aortic valve (AAV) degeneration. The purpose of this study was to prospectively serially measure the magnitude and evolution of the recipient anti-HLA class I antibody response up to 6 years from AAV implant and to correlate serologic data with valve performance by means of a concurrent echocardiographic survey.

METHODS

Cryopreserved AAVs were obtained from multiorgan HLA-typed donors. Nineteen patients younger than 50 years (mean age, 43.3 +/- 8 years) were prospectively studied. After successful surgery, all AAV recipient underwent at 3 and 6 months and each year postoperatively (mean follow-up, 71.9 months) concomitant serum sample collection and two-dimensional transthoracic echocardiography. The presence of anti-HLA antibodies was tested against a panel of lymphocytes obtained from 30 blood donors.

RESULTS

Progressive structural valve deterioration was seen in 6 patients (31.5%) of whom 4 (21%) were reoperated. All pretransplant recipients sera were panel-reactive antibody negative. Seventeen patients (89.4%) demonstrated significant panel-reactive antibody levels, which peaked at 6 months postoperatively, declined from 6 to 24 months, and slowly decreased afterward. In 14 of 19 cases (73.6%) donor-specific HLA antibodies were identified. A strong immunization (6-year persistence of panel-reactive antibody > 70% and peak panel-reactive antibody > 80%) was detected in 31.5% and 36.8% of recipients, respectively. Strong immunization was found to be significantly associated with progressive structural deterioration.

CONCLUSIONS

The immune reaction after cryopreserved AAV implantation is a peculiar long-lasting response occurring in the majority of recipients younger than 50 years of age. An association between a sustained and pronounced immunization and an aggressive AAV degeneration was observed.

Medtronic freestyle valve for right ventricular reconstruction in pediatric ross operations

BACKGROUND

The use of homograft conduits to reconstruct right ventricle (RV) to pulmonary artery (PA) connections is an essential component of the Ross operation. Homograft availability and cost may be problematic when considering the Ross operation. We elected in January 1998 to utilize commercially available xenografts as an alternative to homografts for RV/PA reconstruction in the pediatric Ross operation. Our early results using the Medtronic Freestyle valve (Medtronic, Minneapolis, MN) for RV/PA reconstruction are presented.

METHODS

We reviewed our database for all Ross operations performed on children since January 1998. A total of 16 patients were identified. Eleven children received a Medtronic Freestyle valve, 2 children received a homograft, and 3 children received another type of xenograft. Echocardiographic evaluation of all children who received the Medtronic Freestyle valve was performed at hospital discharge and at two subsequent outpatient evaluations.

RESULTS

The median peak instantaneous pressure gradient across the xenograft was 16 +/- 9 mm Hg (immediately after surgery before hospital discharge); 22 +/- 20 mm Hg at 23 +/- 11 months (first postdischarge follow-up); and 27 +/- 20 mm Hg at 35 +/- 9 months (second postdischarge follow-up). Linear regression analysis revealed an increasing pressure gradient with time (R(2)-adjusted = 0.44, p < 0.0001). At the same three observation points, the xenograft annulus diameter decreased: 25 +/- 1.2 mm; 19 +/- 4.3 mm; and 20 +/- 1.8 mm. Linear regression analysis revealed a decreasing annulus diameter with time (R(2)-adjusted = 0.41, p < 0.0001).

CONCLUSIONS

The Medtronic Freestyle valve provides a possible alternative to homografts for the reconstruction of the RV/PA connection in the pediatric Ross operation. Long-term follow-up is necessary to evaluate this xenograft as an alternative to the homograft.

The Ross procedure in adults: intermediate-term results

BACKGROUND

The durability of the Ross procedure may be optimized by appropriate geometric matching of the aortic and pulmonary artery roots. We employed a surgical strategy to standardize the operation in order to avoid more readily a geometric mismatch.

METHODS

The Ross procedure was performed as a root replacement. Without regard for patient body surface area, the aortic annulus was plicated to 23 mm and externally buttressed with felt. Geometric mismatch of the distal autograft anastomosis was avoided by liberal use of a synthetic interposition graft, and the anastomosis was also externally buttressed with felt. An over-sized pulmonary homograft (27 to 28 mm) was routinely used to reconstruct the right ventricular outflow tract.

RESULTS

Forty-four consecutive patients (27 men and 17 women; mean age, 49 +/- 9 years) were operated on between January 1997 and March 2002. Mean follow-up was 38 +/- 5 months. Twenty-nine patients had aortic stenosis and 15 had aortic regurgitation. Aortic annular plication was done in 41 (93%) and an aortic interposition was used in 14 (32%). There were three hospital deaths, with no subsequent deaths. Only 1 patient required reoperation 2.5 years postoperatively from recurrent endocarditis. No patient has more that "trivial" autograft insufficiency, and the mean autograft gradient was 7 +/- 3 mm Hg. No patient has significant pulmonary homograft stenosis.

CONCLUSIONS

Geometric matching of the aortic and pulmonary roots may be readily accomplished using a standardized approach to the Ross procedure. In turn, this may optimize the durability of the operation.

Report of the Dutch experience with the Ross procedure in 343 patients

OBJECTIVE

Limited information is available on outcome after autograft aortic valve replacement, in particular with respect to the durability of the autograft and of the allograft used to reconstruct the right ventricular outflow tract. A retrospective follow-up study of all patients who underwent a Ross procedure in the Netherlands since 1988 was done to obtain an overview of the Dutch experience with this procedure.

METHODS

From 1988 to January 2000, 348 Ross procedures were performed in nine centers in the Netherlands. Pre-operative, peri-operative and follow-up data from 343 patients in seven centers (99% of all Dutch autograft patients) were collected and analyzed.

RESULTS

Mean patient age was 26 years (SD 14, range 0-58) and male/female ratio was 2.1. Bicuspid valve or other congenital heart valve disease was the most common indication for operation. The root replacement technique was used in 95% of patients and concomitant procedures were done in 12%. Hospital mortality was 2.6% (N=9). Mean follow-up was 4 years (median 3.8, SD 2.8, range 0-12.5). Overall cumulative survival was 96% at 1 year (95% confidence interval (CI) 94-98%) and 94% at 5 and 7 post-operative years, respectively (95% CI 91-97%). At last follow-up, 87% of the surviving patients was in New York Heart Association (NYHA) class I. Independent predictors of overall mortality were pre-operative NYHA class IV/V and longer perfusion time. Autograft reoperation had to be performed in 14 patients and reintervention on the pulmonary allograft in 10 patients. Freedom from any valve-related reintervention was 88% at 7 years (95% CI 81-94%).

CONCLUSIONS

The Dutch experience with the Ross procedure is favorable, with low operative mortality and good mid-term results. Although both the autograft in aortic position and the allograft in the right ventricular outflow tract have a limited durability, this has not yet resulted in considerable reoperation rates and associated morbidity and mortality.