Letter to the Editor Ross procedure valve function, clinical outcomes and predictors after 25 years follow up

The following letter presents an answer of a comment of our work titled "Ross procedure: valve function, clinical outcomes and predictors after 25 years' follow-up," recently published in your journal by Rangwala et al.1 As our colleagues point out, the Ross procedure has excellent survival rates but a significant risk of valve dysfunction and therefore reintervention at follow-up. Although the survival advantage with the Ross procedure appears to be consistent compared with mechanical valve substitutes, this benefit is not as clear compared with biological valve substitutes. However, biological valve substitutes also have significant reintervention rates during follow-up. The different surgical modifications of the Ross procedure have not clearly demonstrated better results in follow-up in terms of autograft reintervention. This procedure can be performed in a medium-volume center with good results as long as adequate patient selection and adequate surgical training are carried out.

Semilunar valve growth and function 10 years after infant heart transplantation: Predicting long-term outcomes of partial heart transplants

INTRODUCTION

Partial heart transplants are a new type of pediatric transplant that replace defective heart valves with the parts of matched donor hearts containing the necessary valves. Short-term outcomes of partial heart transplants are excellent, but long-term outcomes are unknown. In order to predict the long-term outcomes of partial heart transplants, we evaluated long-term growth and function of semilunar heart valves transplanted in infancy as part of a heart transplant.

METHODS

All children who underwent infant heart transplantation at a single center from 1997 to 2014 were included in this study. Children in whom echocardiograms after heart transplantation and after 10 years were not available for review were excluded. The echocardiograms were reviewed by two authors to analyze semilunar valve annulus diameters, Z-scores, peak valve gradients, and valve regurgitation. Statistical difference was determined using two-tailed, paired sample t-tests with Bonferroni correction for multiple comparisons.

RESULTS

Data from 15 patients were analyzed. The aortic valve annulus averaged 1.3 cm (range 0.7-1.8 cm) immediately after transplantation and grew to an average of 1.7 cm (range 1.4-2.3 cm) after 10 years (p < .001). After 10 years, the aortic valve peak gradient avereraged 5.1 mmHg (range 2.1-15.5 mmHg) and none of the valves had more than trivial regurgitation. The pulmonary valve annulus averaged 1.5 cm (range 1.1-2.5 cm) immediately after transplantation and grew to an average of 2.1 cm (range 1.0-2.9 cm) after 10 years (p < .001). After 10 years, the pulmonary valve peak gradient averaged 4.3 mmHg (range 1.1-13.8 mmHg), and 7% of valves had moderate regurgitation.

DISCUSSION

Semilunar heart valves transplanted in infancy as part of a heart transplant demonstrate statistically significant growth and excellent function after 10 years. This predicts excellent long-term outcomes of partial heart transplants.

Decellularized Pulmonary Xenograft Matrix PplusN versus Cryopreserved Homograft for RVOT Reconstruction during Ross Procedure in Adults

BACKGROUND

 Decellularized pulmonary homografts are being increasingly adopted for right ventricular outflow tract reconstruction in adult patients undergoing the Ross procedure. Few reports presented Matrix PplusN xenograft (Matrix) in a negative light. The objective of this study was to compare our midterm outcomes of Matrix xenograft versus standard cryopreserved pulmonary homograft (CPHG).

METHODS

 Eighteen patients received Matrix xenograft between January 2012 and June 2016, whereas 66 patients received CPHG. Using nonparametric statistical tests and survival analysis, we compared midterm echocardiographic and clinical outcomes between the groups.

RESULTS

 Except for significant age difference (the Matrix group was significantly older with 57 ± 8 years than the CPHG group, 48 ± 9 years, p = 0.02), the groups were similar in all other baseline characteristics. There were no significant differences in cardiopulmonary bypass times (208.3 ± 32.1 vs. 202.8 ± 34.8) or in cross-clamp times (174 ± 33.9 vs. 184.4 ± 31.1) for Matrix and CPHG, respectively. The Matrix group had significantly inferior freedom from reintervention than the CPHG group with 77.8 versus 98.5% (p = 0.02). Freedom from pulmonary valve regurgitation ≥ 2 was not significantly different between the groups with 82.4 versus 90.5% for Matrix versus CPHG, respectively. After median follow-up of 4.9 years, Matrix xenograft developed significantly higher peak pressure gradients compared with CPHG (20.4 ± 15.5 vs. 12.2 ± 9.0 mm Hg; p = 0.04).

CONCLUSION

 After 5 years of clinical and echocardiographic follow-up, the decellularized Matrix xenograft had inferior freedom from reintervention compared with the standard CPHG. Closer follow-up is necessary to avoid progression of valve failure into right ventricular deterioration.

Technical considerations and sizing of external annuloplasty in the Ross procedure

Pure aortic regurgitation and dilation of aortic annulus are the most significant risk factors for the failure of pulmonary autograft after the Ross procedure. Aortic annuloplasty has a positive effect on the durability of the autograft. Previously, we described a technique for external annuloplasty with dedicated CORONEO ring. In the present manuscript, we suggest the sizing of annuloplasty based on the diameter of pulmonary autograft annulus.

Influence of preoperative aortic regurgitation on long-term autograft durability and dilatation in children and adolescents undergoing the Ross procedure

OBJECTIVE

Primary aortic insufficiency (AI) is a risk factor for autograft reintervention in adults undergoing the Ross procedure. We sought to examine the influence of preoperative AI on autograft durability in children and adolescents.

METHODS

From 1993 to 2020, 125 consecutive patients between ages 1 and 18 underwent a Ross procedure. The autograft was implanted using a full-root technique in 123 (98.4%) and included in a polyethelene terephthalate graft in 2 (1.6%). Patients with aortic stenosis (aortic stenosis group) (n = 85) were retrospectively compared with those with AI or mixed disease (AI group) (n = 40). Median length of follow-up was 8.2 years (interquartile range, 3.3-15.4 years). The primary end point was the incidence of severe AI or autograft reintervention. Secondary end points included changes in autograft dimensions analyzed using mixed-effect models.

RESULTS

The incidence of severe AI or autograft reintervention was 39.0% ± 13.0% in the AI group and 8.8% ± 4.4% in the aortic stenosis group at 15 years (P = .02). Annulus z scores increased in both aortic stenosis and AI groups over time (P < .001). However, the annulus dilated at a faster rate in the AI group (absolute difference, 3.8 ± 2.0 vs 2.5 ± 1.7; P = .03). Sinus of Valsalva z scores increased in both groups as well (P < .001), but at similar rates over time (P = .11).

CONCLUSIONS

Children and adolescents with AI undergoing the Ross procedure have higher rates of autograft failure. Patients with preoperative AI have more pronounced dilatation at the annulus. Akin to adults, a surgical aortic annulus stabilization technique that modulates growth is needed in children.

Matched comparison of decellularized homografts and bovine jugular vein conduits for pulmonary valve replacement in congenital heart disease

For decades, bovine jugular vein conduits (BJV) and classic cryopreserved homografts have been the two most widely used options for pulmonary valve replacement (PVR) in congenital heart disease. More recently, decellularized pulmonary homografts (DPH) have provided an alternative avenue for PVR. Matched comparison of patients who received DPH for PVR with patients who received bovine jugular vein conduits (BJV) considering patient age group, type of heart defect, and previous procedures. 319 DPH patients were matched to 319 BJV patients; the mean age of BJV patients was 15.3 (SD 9.5) years versus 19.1 (12.4) years in DPH patients (p = 0.001). The mean conduit diameter was 24.5 (3.5) mm for DPH and 20.3 (2.5) mm for BJV (p < 0.001). There was no difference in survival rates between the two groups after 10 years (97.0 vs. 98.1%, p = 0.45). The rate of freedom from endocarditis was significantly lower for BJV patients (87.1 vs. 96.5%, p = 0.006). Freedom from explantation was significantly lower for BJV at 10 years (81.7 vs. 95.5%, p = 0.001) as well as freedom from any significant degeneration at 10 years (39.6 vs. 65.4%, p < 0.001). 140 Patients, matched for age, heart defect type, prior procedures, and conduit sizes of 20-22 mm (± 2 mm), were compared separately; mean age BJV 8.7 (4.9) and DPH 9.5 (7.3) years (p = n.s.). DPH showed 20% higher freedom from explantation and degeneration in this subgroup (p = 0.232). Decellularized pulmonary homografts exhibit superior 10-year results to bovine jugular vein conduits in PVR.

Transcatheter pulmonary valve replacement after pulmonary homograft dysfunction

Pulmonary homograft dysfunction is challenging to treat in patients with a previous Ross procedure, and results in significant morbidity and mortality in case of reoperation. We report the case of a patient with early severe pulmonary homograft stenosis 18 months after a Ross procedure and successful management using transcatheter pulmonary valve replacement.

Ross procedure with personalized external aortic root support

The Ross-Personalized External Aortic Root Support procedure is a surgical aortic valve replacement technique in which the autologous pulmonary valve is transposed in the aortic position to replace the malfunctioning aortic valve and a homograft is implanted in the pulmonary position. To prevent autograft dilatation, a Personalized External Aortic Root Support prosthesis is included in the proximal autograft anastomosis and wrapped around the ascending aorta. The aorta is transected transversely, the aortic valve is resected, and the coronary arteries are mobilized and cut out of the sinuses, leaving a rim. The pulmonary autograft is harvested by transecting the pulmonary artery and part of the right ventricular outflow tract. The autograft is approximated to the aortic root and inverted inside the ventricle. The proximal anastomosis is performed including the prosthesis between the aortic root and the autograft. The coronary buttons are threaded through appropriately positioned and sized holes in the prosthesis and reimplanted into the autograft. The ascending aorta is appropriately adapted and anastomosed with the distal autograft. When the patient is off cardiopulmonary bypass, the prosthesis can be closed longitudinally and is anchored to the distal aortic adventitia.

Ex vivo biomechanical analysis of the Ross procedure using the modified inclusion technique in a 3-dimensionally printed left heart simulator

OBJECTIVE

The inclusion technique was developed to reinforce the pulmonary autograft to prevent dilation after the Ross procedure. Anticommissural plication (ACP), a modification technique, can reduce graft size and create neosinuses. The objective was to evaluate pulmonary valve biomechanics using the inclusion technique in the Ross procedure with and without ACP.

METHODS

Seven porcine and 5 human pulmonary autografts were harvested from hearts obtained from a meat abattoir and from heart transplant recipients and donors, respectively. Five additional porcine autografts without reinforcement were used as controls. The Ross procedure was performed using the inclusion technique with a straight polyethylene terephthalate graft. The same specimens were tested both with and without ACP. Hemodynamic parameter data, echocardiography, and high-speed videography were collected via the ex vivo heart simulator.

RESULTS

Porcine autograft regurgitation was significantly lower after the use of inclusion technique compared with controls (P < .01). ACP compared with non-ACP in both porcine and human pulmonary autografts was associated with lower leaflet rapid opening velocity (3.9 ± 2.4 cm/sec vs 5.9 ± 2.4 cm/sec; P = .03; 3.5 ± 0.9 cm/sec vs 4.4 ± 1.0 cm/sec; P = .01), rapid closing velocity (1.9 ± 1.6 cm/sec vs 3.1 ± 2.0 cm/sec; P = .01; 1.8 ± 0.7 cm/sec vs 2.2 ± 0.3 cm/sec; P = .13), relative rapid opening force (4.6 ± 3.0 vs 7.7 ± 5.2; P = .03; 3.0 ± 0.6 vs 4.0 ± 2.1; P = .30), and relative rapid closing force (2.5 ± 3.4 vs 5.9 ± 2.3; P = .17; 1.4 ± 1.3 vs 2.3 ± 0.6; P = .25).

CONCLUSIONS

The Ross procedure using the inclusion technique demonstrated excellent hemodynamic parameter results. The ACP technique was associated with more favorable leaflet biomechanics. In vivo validation should be performed to allow direct translation to clinical practice.

Complexity and Outcome of Reoperations After the Ross Procedure in the Current Era

BACKGROUND

The Ross procedure has several advantages, but the need for reintervention is inevitable. The aim of this study was to examine the complexity and outcomes of reoperation after the Ross procedure.

METHODS

Retrospective chart review was performed of patients with a prior Ross procedure who underwent reoperation at our institution from September 1991 to January 2021. Demographic, echocardiographic, surgical, and perioperative data were collected. Descriptive statistical and regression analyses were performed.

RESULTS

A total of 105 patients underwent a reoperation at Mayo Clinic after the initial Ross procedure performed at our institution (n = 16; 16.2%) or elsewhere (n = 83; 83.8%). Mean age at the Ross procedure was 27 ± 17 years, and mean age at reoperation at our institution was 37 ± 19 years. Indications for surgical procedure varied, but 64% had autograft regurgitation as 1 of their indications for reoperation. Autograft interventions were performed in 78 patients (74.2%). Pulmonary valve or conduit replacement was performed in 56 patients (53.3%). Double root replacement was performed in 11 patients (10.5%). Aortic reconstruction was performed in 37 patients (38.4%). There were 5 early deaths (5%). During a median follow-up of 6.25 years (3 months-24 years), late deaths occurred in 14 patients (13.1%). Patients with ejection fraction <30% on preoperative echocardiography had shorter duration between the Ross procedure and subsequent reoperation (P = .03).

CONCLUSIONS

Reoperations after the Ross procedure are performed for a wide range of indications, with most due to autograft dysfunction. The number of early deaths is not low. Reoperation after the Ross procedure should be advised before left ventricular systolic dysfunction.

Partial heart transplantation for pediatric heart valve dysfunction: A clinical trial protocol

Congenital heart defects are the most common type of birth defects in humans and frequently involve heart valve dysfunction. The current treatment for unrepairable heart valves involves valve replacement with an implant, Ross pulmonary autotransplantation, or conventional orthotopic heart transplantation. Although these treatments are appropriate for older children and adults, they do not result in the same efficacy and durability in infants and young children for several reasons. Heart valve implants do not grow with the. Ross pulmonary autotransplants have a high mortality rate in neonates and are not feasible if the pulmonary valve is dysfunctional or absent. Furthermore, orthotopic heart transplants invariably fail from ventricular dysfunction over time. Therefore, the treatment of irreparable heart valves in infants and young children remains an unsolved problem. The objective of this single-arm, prospective study is to offer an alternative solution based on a new type of transplant, which we call "partial heart transplantation." Partial heart transplantation differs from conventional orthotopic heart transplantation because only the part of the heart containing the heart valve is transplanted. Similar to Ross pulmonary autotransplants and conventional orthotopic heart transplants, partial heart transplants contain live cells that should allow it to grow with the recipient child. Therefore, partial heart transplants will require immunosuppression. The risks from immunosuppression can be managed, as seen in conventional orthotopic heart transplant recipients. Stopping immunosuppression will simply turn the growing partial heart transplant into a non-growing homovital homograft. Once this homograft deteriorates, it can be replaced with a durable adult-sized mechanical implant. The protocol for our single-arm trial is described. The ClinicalTrials.gov trial registration number is NCT05372757.

Biomechanical Engineering Analysis of Pulmonary Valve Leaflet Hemodynamics and Kinematics in the Ross Procedure

The Ross procedure using the inclusion technique with anticommissural plication (ACP) is associated with excellent valve hemodynamics and favorable leaflet kinematics. The objective was to evaluate individual pulmonary cusp's biomechanics and fluttering by including coronary flow in the Ross procedure using an ex vivo three-dimensional-printed heart simulator. Ten porcine and five human pulmonary autografts were harvested from a meat abattoir and heart transplant patients. Five porcine autografts without reinforcement served as controls. The other autografts were prepared using the inclusion technique with and without ACP (ACP and NACP). Hemodynamic and high-speed videography data were measured using the ex vivo heart simulator. Although porcine autografts showed similar leaflet rapid opening and closing mean velocities, human ACP compared to NACP autografts demonstrated lower leaflet rapid opening mean velocity in the right (p = 0.02) and left coronary cusps (p = 0.003). The porcine and human autograft leaflet rapid opening and closing mean velocities were similar in all three cusps. Porcine autografts showed similar leaflet flutter frequencies in the left (p = 0.3) and noncoronary cusps (p = 0.4), but porcine NACP autografts versus controls demonstrated higher leaflet flutter frequency in the right coronary cusp (p = 0.05). The human NACP versus ACP autografts showed higher flutter frequency in the noncoronary cusp (p = 0.02). The leaflet flutter amplitudes were similar in all three cusps in both porcine and human autografts. The ACP compared to NACP autografts in the Ross procedure was associated with more favorable leaflet kinematics. These results may translate to the improved long-term durability of the pulmonary autografts.

Outcomes of Redo Operations after Ross procedure

BACKGROUND

The Ross procedure is not commonly performed, owing to the procedural complexity and the risk of autograft and/or homograft reoperation. This study examined outcomes of patients undergoing Ross reinterventions at a dedicated Ross center.

METHODS

We retrospectively reviewed 225 consecutive patients who underwent a Ross procedure between 1994 and 2019. Index and redo operation characteristics and outcomes were compared between patients with and those without redo operations. Multivariate analysis was used to identify independent predictors of Ross-related reinterventions. Survival was estimated with Kaplan-Meier analysis.

RESULTS

Sixty-six patients (29.3%) required redo Ross surgery, 41 patients (18.2%) underwent autograft reoperation only, 8 patients (3.6%) had a homograft reintervention, and 17 patients (7.6%) had both autograft and homograft reoperations (12 as a combined procedure and 5 as sequential procedures). The mean time to reintervention was 11 ± 6 years for autograft reoperations and 12 ± 7 years for homograft reoperations. Patients who underwent Ross-related reinterventions were younger (mean, 38 ± 11 years vs 43 ± 11 years; P < .01) and had a higher rate of New York Heart Association class III/IV (56% vs 38%; P = .02) at the index Ross procedure. Most patients undergoing autograft reintervention had aortic insufficiency and/or aneurysm (98.2%; 57 of 58). The primary reason for homograft reintervention was pulmonary stenosis (92%; 23 of 25). The operative mortality of Ross reintervention was 1.5% (1 of 66). Survival at 15 years was similar in patients who required a redo operation and those who did not (91.2% vs 93.9%; P = .23).

CONCLUSIONS

Ross reinterventions can be performed safely and maintain patients at the normal life expectancy restored by the index Ross procedure up to 15 years at experienced centers.

Biomechanical Analysis of the Ross Procedure in an Ex Vivo Left Heart Simulator

BACKGROUND

Neo-aortic pulmonary autografts often experience root dilation and valve regurgitation over time. This study seeks to understand the biomechanical differences between aortic and neo-aortic pulmonary roots using a heart simulator.

METHODS

Porcine aortic, neo-aortic pulmonary, and pulmonary roots (n  =  6) were mounted in a heart simulator (parameters: 100 mm Hg, 37 °C, 70 cycles per minute, 5.0 L/min cardiac output). Echocardiography was used to study root distensibility (percentage change in luminal diameter between systole and diastole) and valve function. Leaflet motion was tracked with high-speed videography. After 30 min in the simulator, leaflet thickness (via cryosectioning), and multiaxial modulus (via lenticular hydrostatic deformation testing) were obtained.

RESULTS

There were no significant differences between aortic and neo-aortic pulmonary leaflet motion, including mean opening velocity (218 vs 248 mm/s, P  =  .27) or mean closing velocity (116 vs 157 mm/s, P  =  .12). Distensibility was similar between aortic (8.5%, 1.56 mm) and neo-aortic pulmonary (7.8%, 1.12 mm) roots (P  =  .59). Compared to virgin controls, native pulmonic roots exposed to systemic pressure for 30 min had reduced leaflet thickness (630 vs 385 µm, P  =  .049) and a reduced Young's modulus (3,125 vs 1,089 kPa, P  =  .077). In contrast, the aortic roots exposed to pressure displayed no significant difference in aortic leaflet thickness (1,317 vs 1,256 µm, P  =  .27) or modulus (5,931 vs 3,631 kPa, P  =  .56).

CONCLUSIONS

Neo-aortic pulmonary roots demonstrated equivalence in valve function and distensibility but did experience changes in biomechanical properties and morphology. These changes may contribute to long-term complications associated with the Ross procedure.

Supporting the Ross procedure: preserving root physiology while mitigating autograft dilatation

PURPOSE OF REVIEW

The purpose of this article is to describe the optimized approach to nonrepairable aortic valve disease in young adults with a Ross procedure, while preserving the dynamic physiology of the aortic root.

RECENT FINDINGS

As the techniques for supporting pulmonary autografts continue to be refined, and the applicability of the Ross procedure continues to expand, an assessment of the various techniques based on aortic root physiology is warranted. Semi-resorbable scaffolds show promise in ovine models for improving the Ross procedure. Recent long-term outcomes for the Dacron inclusion technique in comparison to more physiologic methods of support emphasize the importance of balancing the prevention of early dilatation with the preservation of root haemodynamics. As this review will synthesize, the dynamic physiology of the root may be preserved even in patients at a higher risk of autograft dilatation.

SUMMARY

The favourable long-term outcomes of the Ross procedure can be partly attributed to the ability of the autograft to restore dynamism to the neoaortic root. Patient-specific modifications that respect root physiology can tailor the Ross procedure to address each patient's risk factors for early dilatation and late failure. As such, the Ross procedure should be recognized as an increasingly favourable solution for a wide spectrum of nonpreservable aortic valve disease in young adults.

Eversion for Stabilization: A Standardized Technique for Pulmonary Autograft Inclusion

We have developed a new technique avoiding autograft distortion and narrowing at inclusion during Ross procedure, in order to preserve the functional anatomy and the process of adaptation.

Pulmonary valve tissue engineering strategies in large animal models

In the last 25 years, numerous tissue engineered heart valve (TEHV) strategies have been studied in large animal models. To evaluate, qualify and summarize all available publications, we conducted a systematic review and meta-analysis. We identified 80 reports that studied TEHVs of synthetic or natural scaffolds in pulmonary position (n = 693 animals). We identified substantial heterogeneity in study designs, methods and outcomes. Most importantly, the quality assessment showed poor reporting in randomization and blinding strategies. Meta-analysis showed no differences in mortality and rate of valve regurgitation between different scaffolds or strategies. However, it revealed a higher transvalvular pressure gradient in synthetic scaffolds (11.6 mmHg; 95% CI, [7.31-15.89]) compared to natural scaffolds (4,67 mmHg; 95% CI, [3,94-5.39]; p = 0.003). These results should be interpreted with caution due to lack of a standardized control group, substantial study heterogeneity, and relatively low number of comparable studies in subgroup analyses. Based on this review, the most adequate scaffold model is still undefined. This review endorses that, to move the TEHV field forward and enable reliable comparisons, it is essential to define standardized methods and ways of reporting. This would greatly enhance the value of individual large animal studies.

Long-term results after the Ross procedure with the decellularized AutoTissue Matrix P® bioprosthesis used for pulmonary valve replacement

OBJECTIVES

Since 1967, the Ross procedure has been performed to treat aortic valve disease using homografts for pulmonary valve replacement. The decellularized Matrix P® prosthesis was developed to overcome (some) limitations of homografts. Until now, the long-term outcome data have been unavailable.

METHODS

Between 2002 and 2010, the Ross procedures using the Matrix P prosthesis were performed in 492 adult patients (mean age 57.2 ± 10.6 years, range 21-73 years) at our institution. Patient data were prospectively collected and analysed (3617.3 patient-years, mean follow-up 7.7  ±  4.3 years). Completeness of follow-up at 1, 5 and 10 years was 98.4%, 94.5% and 91.0%, respectively.

RESULTS

Hospital mortality was 3.9% (n  = 19). During follow-up, 121 patients died resulting in a survival rate at 5, 10 and 12.5 years of 82.8  ±  1.7%, 70.4  ±  2.3% and 62.4  ±  2.9%, respectively. Echocardiography revealed a high incidence of relevant dysfunction of the Matrix P prosthesis and subsequent right ventricular failure. Primary reoperation/reintervention was necessary for 150 Matrix P and 48 autografts. Freedom from pulmonary valve reoperation at 5, 10 and 12.5 years was 76.2  ±  2.1%, 58.6  ±  2.9% and 53.4  ±  3.4%, respectively. The autograft function and the left ventricular function showed similar results as previously reported with a freedom from autograft reoperation at 5, 10 and 12.5 years of 91.8  ±  1.4%, 86.1  ±  2.0% and 86.1  ±  2.0%, respectively.

CONCLUSIONS

The Matrix P prosthesis used for the right ventricular outflow tract reconstruction in the Ross procedure showed unfavourable long-term echocardiographic results with a high rate of reoperation/reintervention for structural pulmonary valve failure. As a consequence, long-term survival of this patient cohort was impaired. Based on these findings, the use of the Matrix P prosthesis for pulmonary valve replacement for Ross procedures in adults should not be recommended.

Distinct Expression of Nonmuscle Myosin IIB in Pulmonary Arteries of Patients With Aortic Stenosis vs Insufficiency Undergoing a Ross Procedure

BACKGROUND

Clinical studies have revealed a greater risk of pulmonary autograft dilation after the Ross procedure in patients with preoperative aortic insufficiency (AI). The present study examined whether the morphologic, biomechanical, and cellular properties of the pulmonary artery (PA) from patients with AI were phenotypically different compared with patients diagnosed with aortic stenosis (AS).

METHODS

PA segments were harvested from patients undergoing the Ross procedure for AS (n = 16) and AI (n = 6). Preoperative aortic annulus was significantly larger (P < 0.05) in patients with AI (28.5 ± 1.8 mm) vs AS (22.8 ± 1.2 mm). Morphologic, biomechanical, and cellular phenotypes of the PA were analyzed.

RESULTS

Collagen and elastin content in the media of the PA wall were similar in patients with AS and AI. Elastic modulus and energy loss of the PA were not significantly different between the groups. In the media of the PA, expression of a panel of vascular smooth muscle cell-specific proteins were similar in patients with AS and AI. In contrast, nonmuscle myosin IIB protein levels in the PA of AS patients were significantly higher compared with AI patients, and immunofluorescence identified staining in α-smooth muscle actin-positive vascular smooth muscle cells.

CONCLUSIONS

Despite similar morphological and biomechanical properties, the disparate expression of nonmuscle myosin IIB protein distinguishes the PA of patients with AI from patients with AS. The biological role in vascular smooth muscle cells and the potential contribution of nonmuscle myosin IIB to pulmonary autograft dilation in a subset of AI patients after the Ross procedure remain to be determined.

In vivo performance of freeze-dried decellularized pulmonary heart valve allo- and xenografts orthotopically implanted into juvenile sheep

The decellularization of biological tissues decreases immunogenicity, allows repopulation with cells, and may lead to improved long-term performance after implantation. Freeze drying these tissues would ensure off-the-shelf availability, save storage costs, and facilitates easy transport. This study evaluates the in vivo performance of freeze-dried decellularized heart valves in juvenile sheep. TritonX-100 and sodium dodecylsulfate decellularized ovine and porcine pulmonary valves (PV) were freeze-dried in a lyoprotectant sucrose solution. After rehydration for 24 h, valves were implanted into the PV position in sheep as allografts (fdOPV) and xenografts (fdPPV), while fresh dezellularized ovine grafts (frOPV) were implanted as controls. Functional assessment was performed by transesophageal echocardiography at implantation and at explantation six months later. Explanted grafts were analysed histologically to assess the matrix, and immunofluorescence stains were used to identify the repopulating cells. Although the graft diameters and orifice areas increased, good function was maintained, except for one insufficient, strongly deteriorated frOPV. Cells which were positive for either endothelial or interstitial markers were found in all grafts. In fdPPV, immune-reactive cells were also found. Our findings suggest that freeze-drying does not alter the early hemodynamic performance and repopulation potential of decellularized grafts in vivo, even in the challenging xenogeneic situation. Despite evidence of an immunological reaction for the xenogenic valves, good early functionalities were achieved.

STATEMENT OF SIGNIFICANCE

Decellularized allogeneic heart valves show excellent results as evident from large animal experiments and clinical trials. However, a long-term storing method is needed for an optimal use of this limited resource in the clinical setting, where an optimized matching of graft and recipient is requested. As demonstrated in this study, freeze-dried and freshly decellularized grafts reveal equally good results after implantation in the juvenile sheep concerning function and repopulation with recipients' cells. Thus, freeze-drying arises as a promising method to extend the shelf-life of valvular grafts compared to those stored in antibiotic-solution as currently practised.

Repair of a Quadricuspid Autograft

Aortic valve replacement using a pulmonary autograft is an accepted option in children and young patients. The use of a pulmonary valve with congenital anomaly as autograft is controversial. We describe a case in which a quadricuspid pulmonary valve was used as an autograft in childhood. The patient presented with severe regurgitation 13 years later. Repair was performed with stabilization of the root and cusp prolapse correction, leading to normalized valve function. Despite concerns over the long-term durability of an anomalous pulmonary valve as autograft, good mid to long-term results can be achieved.