Medtronic freestyle valves in right ventricular outflow tract reconstruction

BACKGROUND: Various pulmonary valve substitutes, with their inherent limitations, have been used in children and young adults. We chose the Medtronic Freestyle (Medtronics, Minneapolis, MN) valve because of its excellent hemodynamics, known durability in adults, and design features that allow modifications during implantation. METHODS: Over a 3 1/2 year period the Freestyle valve was implanted in 47 patients age 2 to 58 years (mean 14.2, median 12.0) in the pulmonary position. All patients had pulmonic stenosis and(or) insufficiency from previous operations for tetralogy (27), pulmonary atresia (6), truncus (4), or other diagnosis (10). The indication for surgery was pure pulmonary insufficiency in 11 patients, pulmonic stenosis in 3, and mixed stenosis and insufficiency in 33. Root replacement technique was used with additional enlargement of the pulmonary artery branches in 10 patients. RESULTS: Intraoperatively, one patient sustained a right ventricle tear and one a circumflex coronary artery injury during the dissection. There was one postoperative death. Two patients developed late subvalvular pannus formation, one of whom required reoperation. One patient was found to have an echo gradient of 95 mm Hg due to decreased leaflet motion and underwent cardiac catheterization at which the peak systolic gradient was determined to be 50 mm Hg. He has not required reintervention during his 3 1/2 years of follow-up. The remaining 43 patients have minimal gradients or insufficiency. All surviving patients are in New York Heart Association (NYHA) Class I. CONCLUSIONS: The Medtronic Freestyle valve is an attractive alternative for RVOT (right ventricular outflow tract) reconstruction in children. It is readily available, versatile, and has excellent hemodynamic characteristics. Although long term follow-up is not yet available, longevity of this prosthesis, and freedom from complications, will hopefully be superior to valves with stents.     

Apico-aortic conduits in children with severe left ventricular outflow tract obstruction

BACKGROUND: Infrequently, congenital heart defects are complicated by left ventricular outflow tract obstruction (LVOTO) not amenable to conventional reconstruction. Apico-aortic conduits provide a means of palliating such patients until definitive repair is possible. The purpose of this study was to review a single institution's current experience with apico-aortic conduits. METHODS: The medical records of pediatric patients receiving apico-aortic conduits were reviewed. Demographics, operative techniques, preoperative and postoperative physiologic variables, morbidity, mortality, and functional class were recorded. Off-pump and on-pump procedures were categorized for comparison. RESULTS: Ten cases of apico-aortic conduits for left ventricular outflow tract obstruction were identified. Indications included congenital aortic stenosis, aortic atresia, and subaortic stenosis. Six procedures were performed off-pump and four required median sternotomy with cardiopulmonary bypass as necessitated by concomitant procedures. There was one operative death. The remaining patients demonstrated hemodynamic improvements and are all alive to date. One patient required conduit valve replacement. All patients are in New York Heart Association classification I or II at the time of last follow-up. CONCLUSIONS: Apico-aortic conduits provide a safe and effective treatment alternative for select cases of left ventricular outflow tract obstruction. Off-pump techniques are feasible in the majority of cases. This valuable adjunct should be considered whenever conventional repair of left ventricular outflow tract obstruction is considered prohibitive.     

Results with the freestyle porcine aortic root for right ventricular outflow tract reconstruction in children

BACKGROUND: The ideal choice for valved reconstruction of the right ventricular outflow tract (RVOT) in children is undetermined. This study explores the Freestyle porcine aortic root for these patients. METHODS: From January 1998 to December 2002, 56 patients ages 1.6 to 29.9 years old (mean 11.8 years old) underwent RVOT reconstruction using a Freestyle porcine aortic root. The patients averaged 1.9 prior operations (range 0 to 5) for tetralogy of Fallot +/- pulmonary atresia (28 patients), critical pulmonary stenosis (10 patients), Ross procedure (5 patients), pulmonary atresia/intact ventricular septum (4 patients), complete atrioventricular septal defect +/- tetralogy of Fallot (4 patients), and others (5 patients). At time of RVOT reconstruction, 42 patients (75%) had additional procedures including the following: tricuspid or mitral repair (24 patients), pulmonary arterioplasty +/- Glenn (12 patients), ventricular septal defect closure (5 patients), aortic valve replacement (3 patients), placement of a cardioverter/defibrillator or pacemaker (3 patients), and others (8 patients). RESULTS: One patient developed mediastinitis; another was treated for Candida endocarditis (his excised homograft unexpectedly grew Candida). All patients are well on follow-up from 2 to 60 months (mean 30 +/- 20 months) with no deaths. The patient with endocarditis underwent conduit replacement for recurrent pulmonary stenosis 3.5 years postoperatively. Echocardiography revealed mild or no pulmonary insufficiency in 93%. The calculated mean peak systolic RVOT gradient by echocardiography was 19.7 +/- 15.4 mm Hg. CONCLUSIONS: These data demonstrate excellent results with the Freestyle bioprosthesis for RVOT reconstruction in children. This valve may serve as a readily available alternative to homograft valves in RVOT reconstruction, particularly since early insufficiency seems to be less problematic. Questions of long-term durability and significance of echocardiographic stenosis remain unanswered.     

Wrapped-knitted Dacron and microporous EPTFE conduits for reconstruction of right ventricular outflow tract

The use of the extracardiac conduit for the right ventricle to main pulmonary artery continuity facilitates repair of a wide variety of complex congenital cardiac malformations. Recently, concern has been directed to the appearance of proliferating and obstructive internal peels. In the present study on 18 mongrel dogs, wrapped-knitted Dacron, expanded polytetrafluoroethylene (EPTFE) and wrapped-knitted Dacron/EPTFE conduits were evaluated in the light of internal linings. Macroscopically, the wrapped-knitted Dacron conduits were covered with a thicker and poorly developed neointima, whereas, EPTFE conduits were internally covered with a thin neointima. Microscopically, the neointima on the former was not well healed, while that of the latter was well developed and anchored. Therefore, the EPTFE conduit seems to be superior to the wrapped-knitted Dacron conduit and EPTFE conduit can be used clinically.     

PTFE monocusp valve reconstruction of the right ventricular outflow tract

BACKGROUND: Transannular patching of right ventricular outflow tract obstructive (RVOTO) defects results in pulmonary insufficiency (PI). Biologic monocusp valves (MO) can prevent acute PI but are prone to early degeneration and progressive regurgitation. Polytetrafluoroethylene (PTFE, 0.1 mm) MO leaflets demonstrated favorable characteristics in animal studies, and the technique was applied to a variety of RVOTO anomalies. METHODS: From June 1990 through June 1999, 158 patients underwent either PTFE MO RVOT reconstruction (n = 115 patients; 120 implants) or nonvalved transannular repair (TA) repairs (n = 43 patients; 5 subsequent MO implants) at our institution. Standard MO construction techniques and TA repairs were utilized. Intraoperative, postoperative, and echocardiographic data with a mean interval of 2.6 years (range 6 months to 8 years) were used in retrospective fashion to compare clinical outcomes. In addition, PTFE monocusp valves beyond 6 months postimplant underwent echocardiographic analysis of MO function and durability. RESULTS: There were 4 early (MO-3, TA-1) and no late deaths. Overall, perioperative complications were not significantly different between MO and TA groups, nor were total hospitalization days (9.1 versus 10.7, p = 0.24). However, a significant difference in intensive care unit (ICU) utilization (3.6 versus 5.8 days, p = 0.03) favored MO patients. Patients with tetralogy of Fallot (TOF) and ventricular septal defect/pulmonary atresia (VSD/PA) undergoing the MO implant demonstrated a trend toward improved survival (p = 0.08) when compared to TA repairs. Intraoperative PI was graded mild in the MO group and moderate-severe in the TA group (p = 0.003). Progressive MO regurgitation occurred (mild-moderate) but remained significantly less than the transannular patch repairs (p < 0.05). CONCLUSIONS: Utilization of a PTFE MO valve prevents short-term and significantly reduces midterm PI. It is inexpensive, easy to construct, and demonstrates no evidence of stenosis, calcification, or embolization. Despite longer cardiopulmonary bypass and ischemic times, it reduces ICU stay and, in both TOF and VSD/PA patients, decreases operative morbidity and mortality.     

Wrapped-knitted Dacron and microporous EPTFE conduits for reconstruction of right ventricular outflow tract

The use of the extracardiac conduit for the right ventricle to main pulmonary artery continuity facilitates repair of a wide variety of complex congenital cardiac malformations. Recently, concern has been directed to the appearance of proliferating and obstructive internal peels. In the present study on 18 mongrel dogs, wrapped-knitted Dacron, expanded polytetrafluoroethylene (EPTFE) and wrapped-knitted Dacron/EPTFE conduits were evaluated in the light of internal linings. Macroscopically, the wrapped-knitted Dacron conduits were covered with a thicker and poorly developed neointima, whereas, EPTFE conduits were internally covered with a thin neointima. Microscopically, the neointima on the former was not well healed, while that of the latter was well developed and anchored. Therefore, the EPTFE conduit seems to be superior to the wrapped-knitted Dacron conduit and EPTFE conduit can be used clinically.     

Accessory mitral valve tissue causing severe left ventricular outflow tract obstruction in an adult

Accessory mitral valve (AMV) is a rare cause of left ventricular outflow tract (LVOT) obstruction and is extremely rare in adults. We report a case of an older adult with an AMV that caused severe LVOT obstruction. A parachute-like piece of tissue (the AMV) protruding into the LVOT during systole was first detected in a 45-year-old woman by echocardiography. Because the pressure gradient and dyspnea gradually progressed, she finally underwent a successful operation for removal when she was 48 years old.     

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     

Polytetrafluoroethylene conduits versus homografts for right ventricular outflow tract reconstruction in infants and young children: An institutional experience

Objective

Our institution uses a valved polytetrafluoroethylene conduit as an alternative to homografts. The objective of this study was to investigate the performance of bicuspid valved polytetrafluoroethylene conduits used for right ventricular outflow tract reconstruction in children aged less than 2 years and to evaluate risk factors for earlier conduit explant.

Evaluation of Gore-Tex graft material in the repair of right ventricular outflow tract defect

Following right ventriculotomy, Gore-Tex PTFE vascular grafts were placed in eight neutered male, 6- to 8-week-old, 8- to 12-kg pigs. Ten to 14 months after surgery each pig was evaluated by right heart catheterization. The swine were sacrificed and the hearts were evaluated grossly and microscopically. Comparison of the mean derived cardiovascular hemodynamic parameters in this group with published data on swine and humans indicated normal cardiovascular physiology. Since there was no gradient across the patched areas, it appears that the patches had no adverse effects on the cardiovascular system of growing pigs over an approximately 1-year time period. In addition, the Gore-Tex appeared to be satisfactory for the repair of right ventricular outflow enlargement. Its relative ease of handling, configuration, and lack of aneurysm formation were advantages over other available materials. However, focal calcification and chronic inflammatory reaction did indicate the possibility of long-term prosthetic failure.     

Complications following homograft replacement of the right ventricular outflow tract

Twenty-two patients who had surgical reconstruction of the pulmonary artery and right ventricular outflow tract with a complete or partial valve-bearing aortic homograft have been followed for 1 to 5 years. The following complications were noted: (1) calcification of the homograft (10 patients; noted within the first postoperative year in 6 patients and 2 to 4 years after operation in the remaining 4); (2) pulmonary valve insufficiency (12 patients, including 8 with complete three-cusped aortic homografts); (3) residual obstruction (4 patients), primarily at the distal anastomosis; and (4) sudden, unexpected death (1 patient), which occurred 18 months after operation from rupture of the right ventricular outflow tract.Although the immediate postoperative results with aortic homografts are good, late complications are frequent. We have concluded that aortic homografts are not ideal for right ventricular outflow tract reconstruction. Further development and evaluation of a suitable valve-bearing prosthesis is necessary since the goals of reconstruction in this group of patients continue to be relief of obstruction and establishment of a functionally competent right ventricle-to-pulmonary artery conduit.     

小儿永存动脉干右室流出道重建

目的 总结小儿永存动脉干(PTA)右室流出道重建治疗经验.方法 2000年1月至2007年12月共行PTA根治手术治疗43例,男26例,女17例.年龄1.5个月～3.8岁;体重3.2～23.0kg.Ⅰ型、Ⅱ型和Ⅲ型PTA分别为26例、11例和6例.18例PTA的肺动脉直接下拖至右室流出道切口上缘相吻合,前壁再用心包补片扩大;8例用Homograft管道、14例用牛颈静脉管道连接远端肺动脉和右心室,重建右室流出道;3例Ⅱ型者,肺动脉后壁用左心耳壁与右室流出道上缘做吻合,前壁再用心包补片扩大.结果 术后所有病儿均生存,5例表现为右心功能不全,2例右肺动脉(RPA)压差37.5～47.3 mm Hg(1mm Hg=0.133kPa),术后17d恢复至35.3mm Hg以下.左心室流出道阶差均小于20.3mm Hg.残余VSD(2mm)1例,乳糜胸1例.5例病儿肺血管阻力高,吸一氧化氮(NO)治疗7d左右后好转.随访3个月～3年,2例病儿RPA残余压差24.0～29.3 mm Hg,均无明显右心室或左心室流出道梗阻.结论 肺总动脉后壁直接与右心室切口作吻合重建PTA的右室流出道,早期和远期效果良好.牛颈静脉的带瓣管道的应用,解决了小尺寸同种带瓣管道来源不足的问题,操作简便.     

Options for right ventricular outflow tract reconstruction

The popularity of the Ross operation has drawn attention to the need for a satisfactory replacement of the excised pulmonary valve and artery. Although living autogenous tissue is desirable, it has not been possible to manufacture a satisfactory living conduit, and pulmonary homografts have provided a satisfactory long-term solution. Now, with the increasing shortage of homografts, a number of alternative options have to be considered. The most useful and readily acceptable replacement is a porcine pulmonary xenograft, which is now commercially available. Other prospects for future consideration relate to the use of transgenic pig tissue and developing techniques of tissue engineering. In emergency conditions where a valve conduit is unavailable, a temporary solution is to use a simple tube of autogenous pericardium.     

Isolated right ventricular outflow tract mass presenting as hemoptysis

Infective endocarditis presenting as an isolated right ventricular outflow tract mass is rare. We report a 34-year-old man with no history of congenital heart defect or intravenous drug abuse who presented with hemoptysis and fevers. Diagnostic workup revealed isolated right ventricular outflow tract vegetation. Despite aggressive antibiotic treatment for endocarditis, he developed septic emboli and acute respiratory distress. He was taken to the operating room for successful resection of the ventricular mass.