Ventricular Outflow Tract Replacement Research Articles

Ex vivo evaluation of 3 different right ventricular outflow tract substitutes.

The Ross procedure represents an excellent treatment option in younger patients with aortic stenosis but is limited by poor availability of homografts. In this study, we investigated the hydrodynamic performance of 3 different types of right ventricular outflow tract replacement with pericardium or synthetic material. Three different types of valved conduits were constructed using pericardium and/or synthetic material (Group PEPE: pericardial cusps and pericardial conduit, Group PEPR: pericardial cusps and Dacron conduit, Group PRPR: expanded polytetrafluoroethylene cusps and Dacron conduit). The conduits were designed according to the Ozaki method. Their hydrodynamic performance (effective orifice area, mean pressure gradient and leakage volume) were evaluated in a mock circulation loop at different hydrodynamic conditions. Hydrodynamic assessment showed significantly larger effective orifice area of PEPE and PEPR compared to PRPR under all conditions and there were no significant differences between PEPE and PEPR [for condition 2: PEPE 2.43 (2.35-2.54) cm2, PEPR: 2.42 (2.4-2.5) cm2, PRPR: 2.08 (1.97-2.21) cm2, adjusted pairwise comparisons: PEPE versus PEPR: P = 0.80, PEPE versus PRPR: P < 0.001, PEPR versus PRPR: P < 0.001]. Mean pressure gradient was significantly lower for PEPE and PEPR compared with PRPR, whereas no significant differences were seen between PEPE and PEPR. Leakage volume was significantly lower for PEPE and PEPR compared with PRPR under all conditions while leakage was similar between PEPE and PEPR. Pulmonary graft reconstruction with pericardium cusps showed superior hydrodynamic performance compared with polytetrafluoroethylene cusps. Our results suggest that it could be considered as an alternative substitute for right ventricular outflow tract replacement during the Ross procedure.

Long term efficacy and fate of a right ventricular outflow tract replacement using an elastomeric cardiac patch consisting of caprolactone and D,L-lactide copolymers

For decades, researchers have investigated the ideal material for clinical use in the cardiovascular field. Several substitute materials are used clinically, but each has drawbacks. Recently we developed biodegradable and elastic poly(ε-caprolactone-co-D,L-lactide) (P(CL-DLLA)) copolymers by adjusting the CL/DLLA composition, and evaluated the long-term efficacy and outcomes of these copolymers when used for right ventricular outflow tract (RVOT) replacement. This P(CL-DLLA) material was processed into a circular patch and used to replace a surgical defect in the RVOT of adult rats. Control rats were implanted with expanded polytetrafluoroethylene (ePTFE). Histologic evaluation was performed at 8, 24, and 48 weeks post-surgery. All animals survived the surgery with no aneurysm formation or thrombus. In all periods, ePTFE demonstrated fibrous tissue. In contrast, at 8 weeks P(CL-DLLA) showed infiltration of macrophages and fibroblast-like cells into the remaining material. At 24 weeks, P(CL-DLLA) was absorbed completely, and muscle-like tissue was present with positive staining for α-sarcomeric actinin and cardiac troponin T (cTnT). At 48 weeks, the cTnT-positive area had increased. The biodegradable and elastic P(CL-DLLA) induced cardiac regeneration throughout the 48-week study period. Future application of this material as a cardiovascular scaffold seems promising. Statement of significanceBiomaterials for reconstruction of tissue deficiencies in cardiovascular surgery require having suitable mechanical properties for cardiac tissue and biodegradation resulting in native tissue growth. Several biodegradable polymers such as poly-ε-caprolactone (PCL) and polylactic acid (PLA) have excellent biocompatibility and already been widely used clinically. In general, PCL and PLA are quite mechanically rigid. Meanwhile, significant elasticity is required in the high-pressure environment of the heart while the material is being replaced by new tissue. The present study provides a novel four-armed crosslinked poly(ε-caprolactone-co-D,L-lactide) (i.e., P(CL-DLLA)) material for cardiac patch, which was demonstrated properties including tissue-compatible, super-elastic nature, that made it suitable for long-term, in vivo RVOT repair. This super-elastic biomaterial could be useful for reconstruction of various muscular tissues deficiencies.

Long Term Efficacy and Fate of a Right Ventricular Outflow Tract Replacement Using a Novel Developed Material with Optimized Biodegradation and Elasticity

For decades, researchers have investigated the ideal material for clinical use in the cardiovascular field. Several substitute materials are used clinically, but each has drawbacks. Recently we developed poly(e-caprolactone-co-D,L-lactide) (P(CL-DLLA)) polymers with optimized biodegradation and elasticity by adjusting the CL/DLLA composition, and used these polymers in right ventricular outflow tract (RVOT) replacement to evaluate long-term efficacy and outcomes. This P(CL-DLLA) material was processed into a circular patch and used to replace a surgical defect in the RVOT of adult rats. Control rats were implanted with expanded polytetrafluoroethylene (ePTFE). Histologic evaluation was performed at 8, 24, and 48 weeks post-surgery. All animals survived the surgery with no aneurysm formation or thrombus. In all periods, ePTFE demonstrated fibrous tissue. In contrast, at 8 weeks P(CL-DLLA) showed infiltration of macrophages and fibroblast-like cells into the remaining material. At 24 weeks, P(CL-DLLA) was absorbed completely, and muscle-like tissue was present with positive staining for α-sarcomeric actinin and cTnT. At 48 weeks, the cTnT-positive area had increased. The P(CL-DLLA) with optimized elasticity and biodegradation induced cardiac regeneration throughout the 48-week study period. Future application of this material as a cardiovascular scaffold seems promising.

From Pulmonary Artery Repair to Right Ventricular Outflow Tract Replacement

Abstract Primary pulmonary artery sarcomas are extremely rare tumors with approximately 400 cases reported so far in the literature. These patients present with a wide myriad of symptoms ranging from dyspnea to florid right heart failure, and the presentation is usually misdiagnosed and treated as chronic thromboembolic disease. Diagnostic imaging requires the use of multiple modalities including computed tomography, magnetic resonance imaging and echocardiography. In this E-challenge, we describe the case of a patient diagnosed preoperatively with pulmonic artery stenosis. Intraoperative imaging demonstrated a pulmonary artery lesion with subsequent biopsy and a pathological diagnosis.

The Ross procedure in patients aged less than 18 years: The midterm results

This study reviews a single-center experience with the Ross procedure in infants and young children. From November 1993 to March 2012, 55 children aged less than 17 years underwent a Ross procedure. The patients ranged in age from 2 days to 17 years (median, 5.9 years). Thirteen patients were infants, and 18 patients were preschool children. The predominant indication for the Ross procedure was aortic stenosis. Twenty-seven patients (49%) with left ventricular outflow tract obstruction underwent a modified Ross-Konno procedure. Twenty-five patients (45%) had undergone 40 previous cardiac procedures. Preoperatively, 3 patients showed severe left ventricular dysfunction, with 2 of the patients requiring intubation and inotropic support. Concomitant procedures were performed in 11 patients (20%). Nine patients underwent mitral valve surgery, and 2 patients underwent subaortic membrane resection. Patients were followed up for a median of 66 months (range, 3 months to 17 years). Overall survival at 1, 2, 5, and 10 years was 84.9%. Hospital mortality rate was 13% (7/55 patients). All deaths occurred in neonates or infants, except 1 who was aged less than 4 years. Freedom from reoperation for autograft failure was 100% at 1 year, 96.7% at 5 years, and 73.7% at 10 years. During follow-up, 7 patients required a reoperation on the autograft for dilatation and severe aortic insufficiency. Freedom from reoperation for the right ventricular outflow tract replacement was 56.1% at 10 years. The low rate of autograft failure demonstrates that the Ross procedure is an attractive option for the management of aortic valve disease and complex left ventricular outflow tract obstruction in the pediatric population. However, alternative options must be considered in adolescents and young adults.

Comparison between homografts and Freestyle(R) bioprosthesis for right ventricular outflow tract replacement in Ross procedures

Although data from large series indicate the satisfactory performance of bioprosthetic valves in the right ventricular outflow tract (RVOT), replacement of the pulmonary valve in adult patients undergoing the Ross procedure is usually performed with pulmonary allografts. We evaluated the outcomes of homografts vs. bioprosthetic RVOT replacement after the Ross procedure in adults. Between 1996 and 2011, a total of 186 adult patients (141 male; mean age 44 ± 10 years) underwent aortic root replacement with a pulmonary autograft. The RVOT was replaced with a homograft in 113 patients and with stentless bioprostheses (Medtronic Freestyle(®)) in 73. Patients were followed for a mean of 6 years (range 1-15 years; 1106 patient years). Twelve patients required reintervention owing to dysfunction of the RVOT replacement, which was caused by endocarditis (n = 4), degeneration (n = 2) or stricture at the proximal suture line (n = 6). For homografts, the incidence of reintervention was 1 in 150 patient years, compared with 1 in 36 patient years for stentless bioprostheses (P = 0.007). The median gradient was 15 mmHg for the homograft group and 24 mmHg for bioprosthesis (P < 0.0001). The incidence of gradients >40 mmHg was 10-fold higher in the bioprosthetic group. Patients with bioprostheses in the RVOT position after the Ross procedure showed a significantly higher risk of reintervention or pulmonary valve dysfunction. The main problem, early development of a stricture at the proximal suture line, has to be solved to achieve satisfactory bioprosthetic function in the RVOT.

Combined Aortic Root and Right Ventricular Outflow Tract Replacement with Mechanical Conduits in Adult Patients after Repeated Surgery for Congenital Heart Disease

To manage aortic root aneurysms and right ventricular outflow tract (RVOT) graft dysfunction in adult patients after repeated surgery for congenital heart disease, we performed combined prosthetic aortic root and RVOT replacement. The procedure was performed in 5 patients (2 truncus arteriosus, 2 variants of tetralogy of Fallot, and 1 congenital aortic stenosis), aged 23, 24, 27, 29, and 34 years, who presented with progressive dilation of the aortic root and aortic regurgitation as well as RVOT graft dysfunction. All patients had undergone a median of 3 previous operations and this procedure was their third (in 1), fourth (in 3), or fifth (in 1) operation. The mean interval since the previous operation was 8.2 (3-16) years. Mean cardiopulmonary bypass (CPB) and aortic cross-clamping (AXC) times were 354 (248-422) and 113 (69-142) minutes, respectively. One patient died on the 16th postoperative day from respiratory failure caused by pulmonary bleeding. The other four patients survived the operation and are in New York Heart Association functional class II or less at a maximum of 41 months follow-up. Mechanical valve function in the aortic and pulmonary position is good without any thromboembolic or bleeding complications in all surviving patients. Combined aortic root and RVOT replacement with mechanical conduits in adult patients after repeated surgery for congenital heart disease is a complex operation requiring long CPB time. However, this procedure has the potential to avoid a predictable reoperation associated with conventional biological graft replacement.

Aortic root and right ventricular outflow tract replacement with mechanical conduits in adult patients after repeated surgery for congenital heart disease

Aortic root and right ventricular outflow tract replacement with mechanical conduits in adult patients after repeated surgery for congenital heart disease

The Ross Procedure in Infants and Young Children

This study reviews our experience with the Ross procedure in infants and young children. From September 1993 to September 2004, 52 children less than 15 years of age underwent a Ross procedure. The patients ranged in age from 4 days to 15 years old (median, 5 years). Fifteen patients (29%) were less than 2 years of age. The predominant indication for the Ross procedure was aortic stenosis. Sixteen patients underwent a Ross-Konno procedure for severe left ventricular outflow tract obstruction. Thirty-four patients had 48 previous interventions. Preoperatively, 6 patients showed severe left ventricular dysfunction, and 2 of the patients required ventilation and inotropic support. Concomitant procedures were performed in 8 patients. Three patients had a mitral valve replacement, 2 patients had a ventricular septal defect closure and an aortic arch reconstruction, 2 patients had aortic arch reconstructions, and 1 patient had resection of a coarctation and a ventricular septal defect closure. Patients were followed up for a median of 43 months (range, 1 to 130). Overall survival was 85% +/- 5% at 1 and 82% +/- 5% at 2, 5, and 10 years. Hospital mortality was 5 of 52 patients (9.6%). All deaths occurred in neonates or infants less than 2 months of age, who needed urgent surgery. Three patients died late of noncardiac causes. At last follow-up, all patients were classified in New York Heart Association functional class I or II. No patient had endocarditis of the autograft or the right ventricular outflow tract replacement. During the follow-up, no event of thrombembolism was observed. No patient required the insertion of a permanent pacemaker. Overall freedom from reoperation is 57% +/- 15% at 10 years. One patient required the replacement of the autograft at 6 months postoperatively. The development of mild aortic insufficiency was observed in 24 patients, and moderate aortic insufficiency in 1 patient during follow-up. Freedom from reoperation for the right ventricular outflow tract replacement is 60% +/- 15% at 10 years. The Ross procedure represents an attractive approach to aortic valve disease in young children. However, a high early mortality rate has to be considered when performing this procedure in neonates or infants who present in critical preoperative condition.

In Vivo Evaluation of a Porous, Elastic, Biodegradable Patch for Reconstructive Cardiac Procedures

Several synthetic materials have been used for cardiac reconstruction in patients with complex congenital heart defects. These materials are not viable, do not grow with children, and may necessitate reoperation. We report here on the cardiac implantation of a recently developed, degradable porous material designed to facilitate cellular ingrowth during the healing process. An elastomeric, biodegradable polyester urethane urea (PEUU) was processed into circular scaffolds and used to replace a surgical defect in the right ventricular outflow tract of adult rats. Control rats were implanted with expanded polytetrafluoroethylene. Histologic evaluation was performed at 4, 8, and 12 weeks postsurgery. All animals survived the surgery. Both PEUU and expanded polytetrafluoroethylene were encapsulated with fibrous tissue and had complete endothelialization on the endocardial surface with no aneurysm formation or thrombus noted. With PEUU patching, fibroblast ingrowth occurred at 4 weeks, increasing with time. In contrast, expanded polytetrafluoroethylene patches exhibited no ingrowth and elicited local inflammation that moderated with time. The PEUU patch demonstrated suitable mechanical properties and biocompatible characteristics in the right ventricular outflow tract replacement model, permitting cellular integration and endocardial endothelialization with minimal inflammation. Future application of this material as a cardiovascular scaffold seems promising.

Pericardial tissue valves and gore-tex conduits as an alternative for right ventricular outflow tract replacement in children

Background. There is still no perfect conduit for reconstruction of the right ventricular outflow tract (RVOT) in children. Homografts are not always available in the appropriate size, and degenerate in a few years. This study evaluates the pericardial valve with Gore-Tex conduit as an alternative for RVOT construction. Methods. From January 1, 1993, to September 30, 1999, a pericardial tissue valve was inserted in all patients undergoing RVOT reconstruction or pulmonary valve replacement (PVR) who were large enough to accommodate a tissue valve. In patients without a native main pulmonary artery, a new technique was used to construct an RV-PA conduit out of a flat sheet of Gore-Tex, as Dacron frequently leads to stenosis. Data were collected by retrospective review, follow-up echocardiograms, and assessment by a single cardiologist. Results. There were 48 patients, 22 undergoing a PVR alone and 26 a RV-PA valved Gore-Tex conduit. Diagnosis included tetralogy of Fallot (n = 25); truncus arteriosis (n = 9); ventricular septal defect with PA (n = 5); DORV (n = 4); D-TGA with PS (n = 2); and 1 each IAA with sub AS, VSD with PI, and PS s/p Ross procedure. Patient age ranged from 3 to 33 years and 98% were reoperations. The valve sizes ranged from 19 to 33 mm and the median hospital length of stay was 4 days. There were 2 (4.2%) perioperative and 1 (2.1%) late deaths, none related to the valve or Gore-Tex conduit. At a follow-up of 15 to 86 months (mean 43 ± 16 months), all remaining 45 patients are New York Heart Association class I, all valves are functional, and no patient has required valve or conduit replacement or revision; more importantly, echocardiogram revealed no significant valve or conduit stenosis (mean gradient 16 ± 8 mm Hg) and no evidence of regurgitation or structural degeneration. Conclusions. A pericardial tissue valve and Gore-Tex conduit provides a reliable alternative for RVOT reconstruction in pediatric patients. It is readily available, molds in the limited retrosternal space, and has outstanding intermediate results with no evidence of failure or deterioration up to 7 years after insertion.

Aortic allografts for left ventricular outflow tract replacement in children.

Aortic allografts provide many advantages in children requiring left ventricular outflow tract (LVOT) reconstruction. The low risk of thromboembolic events and freedom from the requirement for anticoagulation are primary benefits. Additionally, excellent hemodynamic results are possible even in the presence of multilevel obstruction. The pulmonary autograft has become the favored approach in most pediatric centers, as the limited longevity of the aortic allograft has now become apparent. However, some children are not candidates for the pulmonary autograft. Thus, the aortic allograft remains a useful aortic valve substitute in children. Using standard aortic root replacement (ARR) or extended aortic root replacement (EARR) techniques, aortic allografts can be used in any circumstance. Young age and small size are predictive of shortened valve longevity and higher operative mortality compared with older children. Reoperation to replace a degenerated aortic allograft can be accomplished safely. Copyright 2000 by W.B. Saunders Company

Aortic Valve and Left Ventricular Outflow Tract Replacement Using Allograft and Autograft Valves: A Preliminary Report

A comparison of allograft and autograft (pulmonary) replacement of the aortic valve has, to our knowledge, not been done in America. Fifty-seven patients (age range, 2 to 70 years; mean age, 30 years) underwent 59 operations for replacement of the aortic valve (20) or entire left ventricular outflow tract (39) using autograft (35) or allograft (24) valves. Many had undergone a previous operation (25) or had concomitant procedures (13). Postoperative mortality was 8.5% (5/59). Two deaths occurred in the allograft group and three in the more complex pulmonary autograft group. One late death occurred. One autograft was replaced with an allograft 7 months postoperatively for severe aortic regurgitation. There have been no episodes of either endocarditis or thromboembolism. Forty-nine of 51 survivors are in New York Heart Association class I. Preliminary results suggest that congenital or acquired disease of the left ventricular outflow tract and aortic valve can be safely and effectively treated with either allograft or autograft valve transplantation.