The Modified Ross Procedure with Prosthetic Graft Wrap Does Not Prevent Autograft Failure

The modified Ross procedure, which involves replacement of the aortic valve with a pulmonary autograft root supported within a Dacron tube graft, was developed with the goal of preventing late autograft dilatation and associated aortic insufficiency. The case is reported of an adult patient who had a bicuspid aortic valve (BAV), underwent a modified Ross procedure, and developed severe aortic insufficiency within one year and subsequently required reoperation for aortic valve replacement. While advances have been made to increase the success of the Ross procedure via modifications to prevent aortic root dilatation, no modifications have yet been devised to improve the ability of the pulmonary valve to withstand systemic aortic pressures. The Ross procedure has significant advantages for children, but the risks and benefits should be carefully considered in adults, especially in those with BAV.

Ross Procedure Following a Dislodged Transcatheter Aortic Valve Replacement

A 36-year-old pregnant woman with a history of rheumatic heart disease and prior aortic valve replacement and mitral valve repair presented to an outside hospital with severe aortic stenosis. The patient had a cardiac arrest upon labor induction and underwent a transcatheter aortic valve replacement (TAVR), which dislodged two days later. Five months later, the patient underwent removal of the dislodged TAVR and a Ross procedure at the authors' institution. The patient was stable upon discharge, with minimal aortic and pulmonary regurgitation. To the authors' knowledge, the present report is the first of the Ross procedure being used under such circumstances. It is suggested that caution be taken when using bioprosthetic and transcatheter aortic valves in young patients, and primary use of the Ross procedure is encouraged at experienced centers.

Iranian homograft heart valves: assessment of durability and late outcome

Durability and the rate of complications of homograft heart valves, adjusted for patient-related contributors and surgical techniques, rely mainly on the quality of allografts which in turn are mirrored in the donor characteristics and most importantly recovery and processing procedures. Aimed to assess the quality, a study was conducted to figure out the durability and late outcome following homograft replacement with valved conduits procured by the Iranian Tissue Bank. Retrospectively, the pre-implantation, perioperative and follow-up data of 400 non-consecutive recipients of cryopreserved heart valves (222 pulmonary and 178 aortic) from 2006 to 2015 were collected and analyzed in terms of variables reflecting late outcome including adverse events and durability. In the context of durability, the event of interest was defined as the need for homograft replacement and homograft-related death. The mean follow-up time (SD) of study entrants (male/female ratio, 1.4) was 49.8 (36.3) months. Median age at the time of implantation was 11 years. Total 10-years mortality was 21 % (84/400), including 66.7 % early (30-days mortality: 56/84) and 33.3 % late (28/84). Overall late complication rate was 2 %. Median survival time was 120 months (95 % CI 83.3-156.6). The pulmonary valves appeared to be more durable (P value <0.001) and survival probabilities in small sized grafts were lower (P value 0.008). One-, five-, and ten-year graft survival was 82, 76 and 73 %, respectively. The evidences suggest that the homografts function satisfactory with low rate of late complications; nevertheless, more emphasis should be given to make long-term durability comparable.

Growth of Pulmonary Autograft after Ross Operation in Pediatric Patients

The Ross procedure is being used increasingly to treat aortic valve disease in pediatric patients; however, there is an ongoing dispute about the durability of the autograft. From November 1996 to September 2003, 32 pediatric patients (mean age, 11 ± 4.5 years) underwent the Ross procedure for various aortic valve diseases, using the root replacement technique. Clinical and echocardiographic follow-up was performed early (within 30 days), at 3 to 6 months, and yearly after surgery. There were no perioperative deaths. The patients were followed-up for up to 7 years with a median interval of 36 months. Actuarial survival at 7 years was 96% ± 3% and there was 100% freedom from re-operation for autograft valve dysfunction or any other cause. The autograft annulus and sinus increased significantly in size during follow-up and the increase in size paralleled the increase in body surface area, with no evidence of disproportional dilatation. The hemodynamics at the latest follow-up were also similar to those at the time of discharge after surgery. Pulmonary autograft replacement of the aortic valve appears to be the ideal solution in pediatric patients, because of relatively low operative risk, excellent late valve function, and real potential for growth.

Early and Midterm Results with the Ross Procedure: A Study of the First 31 Cases

Between 1994 and 2002, 31 patients underwent the Ross procedure by a single surgeon. The mean age was 42 years (24–61), 87% were male and 61% were in New York Heart Association (NYHA) class III–IV. Pure aortic stenosis (AS) was present in 32% of patients, pure aortic regurgitation (AR) in 22% and mixed disease in the rest. The aortic valve was bicuspid in 93.5% of the patients. Autograft implantation was by full root replacement in all cases. Concomitant cardiac surgical procedures were carried out in 10/31 (32%). All patients had at least annual clinical and echocardiographic follow-ups. There was one early death (3%). Overall patient survival was 92.7% at 1 year and 86.1% at 5 years. Twenty-eight (96.55%) were in NYHA class I. Echocardiographic follow-up revealed none to trivial AR in 24/29 (82.75%) and mild AR in 4/29 (13.7%). There was no autograft re-operation before 5 years. The mean gradient across the autograft was low (< 4 mm Hg). There were no incidences of endocarditis or thromboembolism. None of the patients required anticoagulation. Our early experience with the Ross procedure has shown good results in relation to early and midterm morbidity, mortality, autograft, and homograft function.

The Externally Supported Ross Operation: Early Outcomes and Intermediate Follow-Up

BACKGROUND

The externally supported Ross (supported Ross), consisting of a Dacron (DuPont, Wilmington, DE) graft to support the neoaortic root, has been used in adolescent and adult patients to prevent neoaortic dilatation. Outcomes after the supported Ross technique were compared with the Ross procedure using the standard aortic root replacement technique (standard Ross).

METHODS

This was a retrospective analysis of 36 adolescent and young adult patients who underwent the Ross procedure between 1992 and 2013. The outcomes of supported Ross procedures in 26 patients were compared with the Ross procedure in 10 patients. End points included survival, neoaortic root dilatation, development of neoaortic regurgitation, and the need for reintervention.

RESULTS

The median age at operation was 14 years (range, 11 to 31 years), and indications for the operation were mixed lesions (47%), followed by aortic regurgitation (42%) and stenosis (11%). There were no early deaths. The mean follow-up was 2.2 years (range, 1 to 11 years). At the 1-year (p = 0.01) and 3-year (p < 0.05) follow-up, patients in the supported Ross cohort had a smaller neoaortic root z-score. Neither cohort had a large number of patients with significant neoaortic regurgitation, with 1 patient in the supported cohort compared with 3 patients in the standard cohort. Overall, 4 patients (40%) in the standard Ross cohort had required reintervention, including 3 directed at the neoaortic root. One patient in the supported Ross cohort required early reintervention for revision of the right coronary artery.

CONCLUSIONS

At intermediate follow-up, patients who underwent the supported Ross technique were less likely to have neoaortic root dilatation compared with patients who underwent a standard Ross procedure. Further studies are needed to evaluate the long-term durability of this technique, particularly in regards to the development of significant aortic regurgitation, the rate of reintervention, and application to younger and smaller patients.

Modeling study of aortic root for ross procedure: a structural finite element analysis

BACKGROUND AND AIM OF THE STUDY

The Ross procedure involves replacing the diseased aortic valve with the patient's own pulmonary valve (autograft) to form the neoaortic valve, reimplanting the coronary arteries, and inserting a cadaveric homograft into the pulmonary position.

METHODS

In order to model a neoaortic root for the Ross procedure in patients with aortic valve disease, the three-dimensional geometry of a reference aortic valve was reconstructed (reference model A). The diameters of the sinotubular junction (STJ) and maximum sinus were then modified to create four geometric models named B, C, D, and E, with different dimensions. The mechanical behavior of the aortic root was simulated, and the performance of the aortic leaflets assessed in terms of maximum geometric orifice area (GOA) during all cardiac cycle and leaflet contact pressure during closing phase.

RESULTS

The neoaortic valve model showed a maximum GOA of 274.4 mm2 and a maximum leaflet stress of 682 kPa. For models B and C, the leaflet contact pressure was increased by 27.4% and decreased by 4.42%, with STJ diameter increased 1.1-fold and decreased 0.9-fold compared to reference model A. The leaflet contact pressure in models D and E was increased by 3.04% and decreased by 11.5%, while the sinus diameter was increased 1.1-fold and decreased 0.9-fold compared to model A.

CONCLUSION

Increasing the STJ and sinus diameters within a range of 10% can increase the leaflet contact pressure for the aortic root, and vice versa. This may be the reason why neoaortic valve insufficiency occurs long after patients have undergone the Ross procedure.

Human pulmonary autograft wall stress at systemic pressures prior to remodeling after the Ross procedure

BACKGROUND AND AIM OF THE STUDY

Remodeling of the pulmonary autograft upon exposure to systemic pressure can lead to progressive dilatation and aneurysmal pathology. Remodeling is driven by changes in autograft wall stress upon exposure to systemic pressure; however, the magnitude of these changes is unknown. Previously, a porcine autograft finite element model was developed to determine wall stress, but the porcine and human material properties differed significantly. Hence, the study aim was to understand human pulmonary autograft biomechanics that lead to remodeling by determining wall stress magnitudes immediately after the Ross procedure using finite element analysis (FEA).

METHODS

Human pulmonary root was scanned by high-resolution microcomputed tomography to construct a realistic three-dimensional geometric mesh. Stress-strain data from biaxial stretch testing was incorporated into an Ogden hyperelastic model to describe autograft mechanical properties for an adult Ross patient. Autograft dilatation and wall stress distribution during pulmonic and systemic pressures prior to remodeling were determined using explicit FEA in LS-DYNA.

RESULTS

Human pulmonary autograft demonstrated non-linear material properties, being highly compliant in the low-strain region, and stiffening at high strain. The majority of dilatation occurred with < 20 mmHg pressurization. From pulmonary to systemic pressures, the increases in autograft diameter were up to 17%. Likewise, the maximal wall stress increased approximately 14.6-fold compared to diastolic pressures (from 13.0 to 190.1kPa), and six-fold compared to systolic pressures (from 48.6 to 289.6kPa).

CONCLUSION

The first finite element model of the human pulmonary autograft was developed and used to demonstrate how autograft material properties prevent significant dilatation upon initial exposure to systemic pressure. Mild dilatation was noted in the sinuses and sinotubular junction. Autograft wall stress was increased greatly when subjected to systemic pressures, and may trigger biomechanical remodeling of the autograft. Sustained exposure to higher wall stresses, coupled with inadequate remodeling, may lead to future autograft dilatation.

The Ross operation: utilization of the patient’s own pulmonary valve as a replacement device for the diseased aortic valve

Prosthetic heart valves have been outpaced by progress in cardiac surgery. Early biologic valve prostheses consisted of tissues mounted on a rigid stent, and did not require anticoagulation, but rarely survived two decades. Subsequently, durable mechanical valve prostheses dominated despite, the requisite anticoagulation. The mechanical design remains imperfect, with obstruction to flow, turbulence, hematological changes and also, occasionally audible clicks. Reports documenting superior function for cryopreserved human aortic heart valves (homografts) without these problems, albeit with limited durability, followed. The marketing of 'stentless biologic valves', mimicking these attributes was a reaction to the shortage of homografts. These imperfections explain the rediscovery of the Ross operation, in which the patient's pulmonary valve (autograft) is excised to replace the aortic valve. The autograft is living tissue, complete with attributes of a healthy heart valve, including growth and durability. The pulmonary valve, where lower pressure and oxygen saturation retards degeneration, is substituted with a pulmonary homograft. The Ross operation is exacting and leaves the patient with two potentially malfunctioning valves.

A modification of the pulmonary autograft procedure to prevent late autograft dilatation

Although the pulmonary autograft procedure for aortic valve replacement is a commonly utilized option for children, its use is diminishing in adult-aged patients. One commonly cited concern is the tendency for the pulmonary autograft to dilate in the aortic position. This article reviews a technique we have used in 36 patients since October, 2004 that stabilizes the autograft so that it cannot dilate. There have been no operative or late deaths and the autograft has continued to function in 34 patients. Two patients have undergone autograft replacement because of early failure, which we believe was likely related to technical considerations in our early technique (first reported in the 2005 STCVS Pediatric Cardiac Surgery Annual). The technical modifications described in this article have produced a more reliable and reproducible technique and have not resulted in any autograft failures in our experience. One patient with Marfan's syndrome and a bicuspid aortic valve is symptom- and dilation-free 8 years post op, with no autograft or pulmonary homograft insufficiency, normal activity and a stable aortic root by serial echocardiography. Our results suggest that this technique might be applicable for selected adult patients in whom autograft growth is not necessary and for whom the risk of autograft dilatation would provide a reason to avoid a pulmonary autograft procedure.

Double freestyle valve replacement in a patient with a prior Ross procedure

Following a Ross procedure, patients may require reintervention for valvular stenosis or insufficiency of either the pulmonary autograft or the pulmonary homograft. Herein is reported a double use of the Medtronic Freestyle stentless bioprosthesis in a patient who previously had undergone a Ross procedure.

Fibrosing mediastinitis with severe bilateral pulmonary artery narrowing: RV-RPA bypass with a homograft conduit

Although fibrosing mediastinitis is uncommon, it is a devastating sequela of certain granulomatous diseases. The compression of mediastinal structures can lead to severe cardiopulmonary symptoms. We report the case of a 50-year-old woman who presented with severe bilateral branch pulmonary artery compression 6 months after bilateral pulmonary artery stenting. We performed bypass surgery with use of a homograft conduit. Seven months postoperatively, the homograft and stent in the right pulmonary artery were patent, and the patient had resumed activities of daily living, including full-time employment. In addition to reporting this patient's case, we discuss surgery as an alternative to stenting in patients with fibrosing mediastinitis.

Pulmonary homograft morphology after the Ross procedure: a computed tomography study

BACKGROUND AND AIM OF THE STUDY

In patients undergoing the Ross procedure the autograft morphological characteristics have been well studied, but those of the homograft are less clear. The study aim was to describe the radiomorphological homograft characteristics in Ross patients, and to compare them with such characteristics in normal (control) subjects.

METHODS

A total of 79 Ross patients (68 males, 11 females; mean age 43 +/- 12.3 years) underwent a computed tomography (CT) scan at a mean of 31 +/- 26 months after surgery. A group of 123 patients without cardiovascular disease served as controls. Cryopreserved homografts were implanted in all Ross patients, with the majority being obtained from a single source.

RESULTS

The mean donor age was 47 +/- 11 years, and the mean homograft diameter 25.4 +/- 1.3 mm (as provided at source). Electrocardiographic-gated CT reconstructions were used for the measurements. The smallest diameters were at the proximal anastomosis, and maximum diameters at the distal anastomosis (p <0.001). In controls, the minimum diameter was just proximal to the pulmonary valve annulus. In Ross patients, the homograft diameters were significantly smaller at all levels compared to controls. This effect persisted after taking into consideration patient age, height, gender, body surface area, and time since surgery. Notably, the measured homograft diameters were significantly smaller than those provided at source.

CONCLUSION

The study results provided evidence of homograft shrinkage at all levels after the Ross procedure but, most prominently, at the level of the proximal suture line. This may have implications for novel preservation methods, as well as homograft size selection and implantation techniques.

Polyester mesh: an alternative material for reinforcing the pulmonary autograft root

Today, it is widely accepted that the pulmonary autograft should be reinforced when used as a root in the Ross operation. Various techniques using a vascular conduit have been reported. Herein is described an alternative technique, using a polyester mesh, that was applied in a 15-year-old boy with recurrent congenital stenosis. The advantages of using a mesh rather than a solid vascular prosthesis are discussed.

Cryopreserved homograft in the Ross procedure: outcomes and prognostic factors

BACKGROUND AND AIM OF THE STUDY

The study aim was to determine the dynamics and risk factors related to cryopreserved homografts implanted to reconstruct the right ventricular outflow tract (RVOT) during the Ross procedure.

METHODS

A retrospective study, conducted between 1993 and 2009, included 107 consecutive patients who underwent a Ross procedure with implantation of a homograft (102 pulmonary, five aortic). The median patient age at implant was 18.8 years (range: 2 months - 67 years). The main cardiac defects were congenital aortic stenosis (n = 44), congenital aortic regurgitation (n = 20), and combined (n = 23) and acquired (n = 20) aortic regurgitation. The study endpoints were homograft stenosis (peak gradient > or = 20 mmHg), regurgitation (grade > or = moderate), homograft dysfunction (stenosis > or = 50 mmHg or regurgitation > or = moderate), homograft explant, and failure (explant or balloon dilation). The mean follow up was 5.7 +/- 0.4 years. The statistical analysis was conducted using univariate and multivariate Cox regression tests.

RESULTS

The overall patient survival was 97% at 18 years. Homograft stenosis occurred in 54% of patients, regurgitation in 18%, dysfunction in 27%, explant in 5%, and failure in 6%. Freedom from homograft dysfunction was 75% and 55% at five and 10 years, respectively, while freedom from homograft failure was 99% and 84% at five and 10 years, respectively. The main multivariate risk factors for dysfunction were: homograft diameter < 22 mm (OR: 11, p = 0.019), aortic homograft (OR: 18, p = 0.019) and preoperative right ventricle/left ventricle pressure ratio > 0.4 (OR: 5, p = 0.018). Univariate risk factors for failure were: homograft diameter < 22 mm (p = 0.006), donor age < 30 years (p = 0.03), cold ischemia time < 2 days (p = 0.04), and decontamination time < 12 h (p = 0.01).

CONCLUSION

In the Ross procedure, the cryopreserved homograft represents an excellent means to reconstruct the RVOT, with a good long-term longevity. Almost 85% of patients did not require any surgery or percutaneous intervention at 10 years after implantation. The homograft long-term durability depends on both homograft-related and patient-related factors. Pulmonary homografts, with a diameter > 22 mm, a donor age > 30 years, and a cold ischemia time > 2 days are to be preferred.

The Ross full root replacement in adults with bicuspid aortic valve disease

BACKGROUND AND AIM OF THE STUDY

Bicuspid aortic valve disease (BAVD) is the most common congenital cardiac lesion causing aortic stenosis in adults. This lesion can be associated with a histological abnormality of the aortic wall and dilated or aneurysmal ascending aorta. In younger patients, the Ross operation offers several advantages over conventional aortic valve replacement (AVR); however, the rationale of performing this procedure on adults in the face of BAVD have been questioned.

METHODS

Between 1994 and 2009, a total of 101 adult patients (mean age 36 years; range: 18-61 years) with BAVD underwent the Ross full root replacement at the authors' institution. Of these patients, 23 (23%) had an aneurysmal ascending aorta (4.0-5.2 cm) associated with BAVD which was resected at the time of, or subsequent to, a Ross AVR. The end point of the study was freedom from Ross autograft dilatation > 4.0 cm, dysfunction, or valve repair or replacement.

RESULTS

The mean follow up was 6.0 +/- 3.9 years. At the latest follow up, 19 patients (19%) had a dilated ascending aorta with a mean size 45.1 mm (range: 40-64 mm). Eight patients (8%) required a redo operation on the autograft. Three of seven patients undergoing reoperation had their autograft valve preserved; the remaining four underwent a modified Bentall root replacement. One patient had a repair of a left ventricular pseudoaneurysm below the Ross valve. Only three patients with preoperative ascending aorta dilation developed late autograft dilation. Freedom from autograft dilatation > 4.0 cm, dysfunction, repair or replacement was 80% at 10 years.

CONCLUSION

Mid-term results indicate that Ross AVR in adults with BAVD had good outcomes, with a low incidence of autograft-related complications. In almost half of the patients undergoing reoperation, the autograft valve was preserved. The incidence of autograft valve insufficiency and dilatation might be further reduced by: (i) aggressively treating any postoperative systemic hypertension; (ii) externally fortifying the annulus and sinotubular junction of the autograft with Dacron strips; and/or (iii) replacing a dilated ascending aorta with a Dacron interposition graft. The preoperative diagnosis of BAVD and/or aneurysmal ascending aorta is not predictive of late autograft dilatation or failure.

Right ventricular outflow tract reconstruction with decellularized porcine xenografts in patients with congenital heart disease

BACKGROUND AND AIM OF THE STUDY

Decellularized xenogeneic pulmonary valves have been introduced for right ventricular outflow tract (RVOT) reconstruction in congenital heart disease. In the present study, the intermediate-term results from three institutions were analyzed.

METHODS

Between January 2006 and September 2008, a total of 61 patients (median age 7 years; range: 9 days to 50 years; median body weight 21 kg; range: 1.9-140 kg) underwent RVOT reconstruction with either the Matrix P (n = 9) or Matrix P Plus (n = 52) tissue-engineered conduit. Eighteen patients underwent surgery in infancy, and 31 patients had previously undergone one or more RVOT interventions or operations.

RESULTS

The valve sizes ranged from 11 to 27mm. Five patients died during the hospital stay or within three months, from non-valve-related causes; hence, the early mortality was 8.2%. No deaths occurred during the follow up period. Reoperation due to valve failure became necessary in four patients; three patients underwent RVOT interventions due to distal anastomotic stenosis, and six reinterventions were performed distal to the valve due to hypoplastic branch pulmonary arteries. Patients with valve implantation during infancy showed a composite freedom from valve-related reoperation, catheter intervention or valve dysfunction (defined as dP(max) > 40 mmHg) of 87% at one and three years postoperatively. Both, computed tomography and magnetic resonance imaging studies demonstrated normal structural features, with no evidence of calcification.

CONCLUSION

The Matrix P/Matrix Plus conduit represents a viable alternative for RVOT reconstruction in patients with congenital heart disease. The intermediate-term performance of the conduits was favorable compared to that of other currently available implants.

Performance of SynerGraft decellularized pulmonary homograft in patients undergoing a Ross procedure

BACKGROUND

In the Ross aortic valve replacement (AVR), a pulmonary allograft normally replaces the autotransplanted pulmonary valve. Despite the Ross advantages vs other AVR procedures, there has been a small but unpredictable risk of early structural allograft valve deterioration, usually manifested by shrinkage and right ventricular outflow tract obstruction. This study analyzed our results of the Ross AVR using a new CryoValve SynerGraft (CryoLife Inc, Kennesaw, GA) decellularized pulmonary allograft (SGDPA) and compared it with the standard cryopreserved allograft (SCA) used during the same period.

METHODS

Between 2000 and 2009, 29 patients received a SGDPA and 34 received the SCA during Ross AVR. Patients were a mean age at implant of 28.6 ± 16.0 years (range, 4 months to 58 years). Retrospective data included reported adverse events, and the most recent hemodynamic data were collected.

RESULTS

No early or late deaths or significant morbid events occurred during the mean follow-up of 4.9 ± 2.7 years (range, 2 months to 9 years). No patient required conduit reoperation. The median peak gradient at discharge was 12 mm Hg and was not significant at last follow-up. No deterioration in conduit valve function occurred in the SGDPA group. Mild conduit regurgitation developed in several SCA patients, and one patient had moderate regurgitation. No patient reached our definition of conduit dysfunction (peak gradient: 40 mm Hg or >2+ regurgitation).

CONCLUSIONS

The SGDPA conduit is an alternative to the SCA for the Ross AVR. The early clinical and hemodynamic results are encouraging but were not significantly different from the SCA. SynerGraft technology may provide a more durable option for patients who need right ventricular outflow tract reconstruction. Further long-term follow-up is needed to see if this decellularization process improves long-term allograft durability.

Finite element modeling of the pulmonary autograft at systemic pressure before remodeling

BACKGROUND AND AIM OF THE STUDY

Pulmonary autograft dilatation requiring reoperation is an Achilles' heel of the Ross procedure, as exposure to systemic pressure increases autograft wall stress, which may in turn lead to tissue remodeling and aneurysmal pathology. However, the magnitude of autograft wall stress with the Ross procedure is unknown. The study aim was to develop a realistic finite element (FE) model of the autograft, and to perform simulations at systemic pressure to determine wall stress distribution immediately after the Ross operation.

METHODS

The porcine pulmonary root geometry was generated from high-resolution microcomputed tomography (microCT) images to create a mesh composed of hexahedral elements. Previously defined constitutive equations were used to describe the regional material properties of the native porcine pulmonary root. The anterior and posterior pulmonary arteries, and each of the pulmonary sinuses, were best described by non-linear, anisotropic Fung strain energy functions, and input individually into the model. Autograft dilatation and wall stress distribution during pulmonary and systemic loading prior to remodeling were determined using explicit FE analysis in LS-DYNA.

RESULTS

The autograft was highly compliant in the low-strain region, and the majority of dilation occurred with < 30 mmHg of pressurization. During pulmonic loading, a typical inflation/deflation was observed between systole and diastole, but the autograft remained almost completely dilated throughout the cardiac cycle at systemic pressure. Although the systolic blood pressure was 380% greater in the aortic than in the pulmonary position, the peak systolic diameter was increased by only 28%. The maximum principal wall stress increased approximately 10-fold during systole and 25-fold during diastole, and was greater in the sinus than the distal artery for all simulations.

CONCLUSION

Under systemic loading conditions, the pulmonary autograft remained fully dilated and experienced large wall stresses concentrated in the sinus. The future correlation of this model with explanted autografts may lead to an improved understanding of tissue remodeling following the Ross procedure.