In vitro evaluation of right ventricular outflow tract reconstruction with bicuspid valved polytetrafluoroethylene conduit

Conduits available for right ventricular outflow tract (RVOT) reconstruction eventually become stenotic and/or insufficient due to calcification. In order to reduce the incidence of reoperations we have developed and used a bicuspid valved polytetrafluoroethylene (PTFE) conduit for the RVOT reconstruction. The purpose of this study is to investigate the hemodynamic performance of the new design using a pediatric in vitro right heart mock loop. PTFE conduit has been used for the complete biventricular repair of 20 patients (age 1.7±6 years) with cyanotic congenital defects. To account for the large variability of conduit sizes, 14, 16, 22, and 24-mm conduit sizes were evaluated using an in vitro flow loop comprised of a pulsatile pump with cardiac output (CO) of 1.2-3.2L/min, bicuspid valved RVOT conduit, pulmonary artery, venous compartments, and the flow visualization setup. We recorded the diastolic valve leakage and pre- and post-conduit pressures in static and pulsatile settings. In vitro valve function and overall hemodynamic performance was evaluated using high-speed cameras and ultrasonic flow probes. Three-dimensional flow fields for different in vivo conduit curvatures and inflow regimes were calculated by computational fluid dynamics (CFD) analysis to further aid the conduit design process. The average pressure drop over the valved conduits was 0.8±1.7mm Hg for the CO range tested. Typical values for regurgitant fraction, peak-to-peak pressure gradient, and effective office area were 23±2.1%, 13±2.4mm Hg, and 1.56±0.2 cm(2) , respectively. High-speed videos captured the intact valve motion with asymmetrical valve opening during the systole. CFD simulations demonstrated the flow skewness toward the major curvature of the conduit based on the pulmonic curvature. In vitro evaluation of the bicuspid valved PTFE conduit coincides well with acceptable early clinical performance (mild insufficiency), with relatively low pressure drop, and intact valve motion independent from the conduit curvature, orientation or valve location, but at the expense of increased diastolic flow regurgitation. These findings benchmark the baseline performance of the bicuspid valved conduit and will be used for future designs to improve valve competency.     

Minimally invasive transventricular implantation of pulmonary xenograft

Minimally invasive valve replacement is now a clinical reality. A number of ingenious techniques have been described for percutaneous aortic and pulmonary valve replacement as well as transventricular aortic valve replacement. We describe a technique for transventricular pulmonary valve replacement utilizing off-the-shelf bovine tissue valve, vascular stents, and simplified delivery system. After median sternotomy with limited exposure of the right ventricle, Contegra 200 pulmonary valve (Medtronic, Inc., Minneapolis, MN, USA) is transfixed inside a CP stent (NuMed, Inc., Hopkinton, NY, USA) using multiple 5/0 prolene sutures. The valve/stent composite is crimped on a Cristal balloon catheter (Balt, Montmorency, France). The valve/stent and the balloon are then introduced via a small purse-string placed at the RVOT. The stent/valve composite is then expanded in the pulmonary valve position.     

Transcatheter heart valve with variable geometric configuration: in vitro evaluation

Clinically, the current transcatheter aortic valve (TAV) technology has shown a propensity for paravalvular leakage; studies have correlated this flaw to increased calcification at the implantation site and with nonideal geometry of the stented valve. The present study evaluated the hydrodynamics of different geometric configurations, in particular the intravalvular considerations. Three TAV devices were made to create a representative, size 26 mm TAV. Hydrodynamics were assessed using a pulse duplicator. The geometries tested were composed of the nominal, elliptical, triangular, and undersized shapes; along with half-constriction, a conformation in which only a portion of the stent was constrained. The TAVs were assessed for transvalvular pressure gradient (TVG), effective orifice area (EOA), and regurgitant fraction. The nominal-sized shape posed a larger TVG (6.2 ± 0.3 mm Hg) than other configurations (P < 0.001) except the undersized valves. EOA of the nominal sized TAV (1.7 ± 0.1 cm(2) ) was smaller than that of the triangular and half-elliptical versions (P < 0.001). The half- and full-undersized geometries had EOAs smaller than the nominal type (P < 0.001). Nominal shape had smaller regurgitation (6.7 ± 1.4%) than all configurations (P < 0.001) except for the half-undersized (4.0 ± 0.7, P < 0.001) with no statistically significant difference from the full-undersized (6.8 ± 1.3, P = 0.724). The testing of variable geometries showed significant differences from the nominal geometry with respect to TVG, EOA, and regurgitant fraction. In particular, many of these nonideal configurations demonstrated an increased intravalvular regurgitation.     

Off-bypass implantation of a self-expandable valved stent between inferior vena cava and right atrium

A glutaraldehyde preserved valved bovine jugular xenograft mounted in a nitinol 'Z' stent, expandable from 7 to 28 mm of internal diameter, was evaluated in vitro (column of water developing a pressure of 45 mmHg and a mock loop including a pulsatile pump) and in vivo in five adult pigs with intra-vascular ultrasound to measure the inferior vena cava diameter via a retroperitoneal access. Through a stent-graft delivery system (24 French) the self expandable valved stent was implanted off-bypass in the inferior vena cava, between hepatic veins and cavo-atrial junction, with flow and pressure gradient recording. The mean length of the valved stent was 22.80+/-1.06 mm, the mean internal diameter 20.97+/-0.5 mm and the mean external diameter 26.67+/-0.9 mm. The valve leaking under pressure was 32.5+/-12.3 ml/min. The mean pressure gradient recorded across the self expandable valved stent implanted in the inferior vena cava was 1.0+/-0.5 mmHg (range 0-2 mmHg). Intra-vascular ultrasound showed partial opening and closing of the valve (mean area reduction from 148.5 to 81.5 mm2), with almost complete occlusion only during deep breaths. The in vitro and in vivo experiments confirmed the feasibility of potential application of the self-expandable valved stent implanted off-bypass in the inferior vena cava for late conversion of failing total cavo-pulmonary connection; intra-vascular ultrasound allows for adequate implantation and evaluation.     

牛颈静脉带瓣补片在复杂先天性心脏病患者右心室流出道重建中的应用

目的评价牛颈静脉带瓣补片应用于重建右心室流出道的近期效果。方法回顾性分析2009年5月至2010年3月武汉亚洲心脏病医院行牛颈静脉带瓣补片重建右心室流出道60例患者的临床资料,男42例,女18例;年龄5个月～33(6.2±8.9)岁,其中34例<1岁;体重(27.5±24.0)kg。术前临床诊断为法洛四联症38例,右心室双出口合并肺动脉狭窄22例。所有患者均行一期完全修复术,有4例因为侧枝循环较多,术前采取介入侧枝封堵。全组患者肺动脉瓣瓣环直径均小于正常值2个标准差,均采取跨瓣环补片重建右心室流出道。随访时间18～26(21.2±4.6)个月。结果手术无死亡,也无因流出道严重狭窄和严重肺动脉瓣反流需再次手术者。有3例患者术后早期因为侧枝循环较多,拔除气管内插管后出现肺水肿,再次气管内插管;4例患者因出血需二次开胸止血,其他患者术后均顺利康复出院。体外循环时间(84.0±22.0)min,主动脉阻断时间(42.0±12.0)min。术后即刻右心室流出道压力阶差(18.0±4.5)mm Hg,术后最后一次随访的经胸超声心动图检查提示,右心室流出道压力阶差为(19.2±5.4)mm Hg,两者差异无统计学意义(P>0.05)。术后即刻肺动脉瓣反流程度:轻微反流32例(1+),轻度反流28例(2+);术后最后一次随访的经胸超声心动图检查提示,反流程度:轻微28例(1+),轻度27例(2+),中度5例(3+);两者反流程度差异无统计学意义(P>0.05)。牛颈静脉带瓣补片及瓣叶组织均未见钙化,瓣叶活动良好。无牛颈静脉血栓形成及感染性心内膜炎发生。结论对法洛四联症和右心室双出口合并肺动脉狭窄的患者,牛颈静脉带瓣补片是右心室流出道跨瓣环重建的一种良好材料,无相关的严重并发症发生,近期右心室流出道压力阶差没有明显增加,肺动脉瓣抗反流性能良好;远期效果还需进一步随访观察。     

Self-expandable valved stent of large size: off-bypass implantation in pulmonary position.

OBJECTIVE: To evaluate the feasibility of the off-bypass implantation of a self-expandable valved stent of large size in pulmonary position. MATERIALS AND METHODS: A glutaraldehyde preserved valved bovine jugular xenograft with internal diameter = 22 mm, mounted in two rings of nitinol 'Z' stent, expandable from 7 to 24 mm of internal diameter, was acutely evaluated in 6 adult pigs, mean body weight 55.6 kg (range 47-67 kg). Through a stent-graft delivery system (24 French) the self expandable valved stent was implanted off-bypass in pulmonary valve position by trans-ventricular approach through median sternotomy. RESULTS: The mean diameter of the main pulmonary artery measured was 21.7 +/- 1.6 mm. The mean length of the self expandable valved stent was 23.1 +/- 0.7 mm, the mean internal diameter 21.6 +/- 0.7 mm and the mean external diameter 26.3 +/- 0.7 mm. The mean peak pressure gradient recorded across the valve was 6.33 +/- 2.8 mmHg (range 4.5-9.6 mmHg) at Doppler echocardiography, and 4.5 +/- 3.1 mmHg (range 0-7 mmHg) at invasive measurement, with a pulmonary blood flow of 3.03 +/- 0.05 l/min. Intra-vascular ultrasound showed complete opening and closure of the valve (mean area reduction from 315.08 +/- 54.13 to 0 mm2). CONCLUSIONS: (a) Off-bypass implantation of self-expandable valved stent is feasible in pulmonary position; (b) off-bypass surgical approach allows for valved stent implantation of adult size with adequate hemodynamic functioning; and (c) intra-vascular ultrasound makes implantation and evaluation easy and reproducible.     

Long-term outcomes of expanded polytetrafluoroethylene conduits with bulging sinuses and a fan-shaped valve in right ventricular outflow tract reconstruction

Objective

Various types of conduits are available for right ventricular outflow tract (RVOT) reconstruction. We have developed an expanded polytetrafluoroethylene (ePTFE) conduit with bulging sinuses and a fan-shaped ePTFE valve. This study summarized the results of a multicenter study evaluating the valved ePTFE conduit.

A new treatment option for pulmonary valvar insufficiency: first experiences with implantation of a self-expanding stented valve without use of cardiopulmonary bypass.

OBJECTIVE: Pulmonary regurgitation is the predominant problem in the long-term follow-up of tetralogy of Fallot (TOF) patients after primary repair. Apart from standard homograft implantation, a percutaneous valve delivery approach has been described recently. A right ventricular outflow tract (RVOT) diameter of greater than 22mm, however, precludes percutaneous valve delivery. We describe a novel technique with a transventricular implantation of a stented bio-prosthesis without cardiopulmonary bypass that allows for implantation of prosthesis with diameters greater than 22mm. METHODS: All patients (9-27 years of age) had undergone total correction of TOF at a mean age of 4.2+/-4.0 years. The RVOT was enlarged at that time with a transannular patch in all but one patient. All patients presented with severe pulmonary regurgitation without any significant RVOT obstruction. Mean MRI pulmonary regurgitation was 53+/-8%. The mean magnetic resonance imaging (MRI) right ventricular end diastolic volume index (RVEDVI) was 143+/-23ml/m(2), with a mean MRI right ventricular ejection fraction (RVEF) of 46+/-9%. In another two patients indication for treatment was based on reduced exercise capacity with patients being in NYHA Class III. After repeat sternotomy, a porcine valve mounted inside a self-expandable stent, covered with No-React treated porcine pericardium (Shelhigh, Model NR-4000MIS), was introduced just beneath the RVOT without use of cardiopulmonary bypass. External sutures were placed at the proximal and distal site of the valve to ensure fixation. RESULTS: The implantations were uneventful, with the patients hemodynamically stable throughout the procedure. One patient with severely dilated RVOT (up to 31mm) exhibited paravalvular leakage and the valve was replaced by a homograft after 2 days. At 6-12 month follow-up the remaining five patients exhibited no more than mild pulmonary regurgitation. The mean MRI RVEDVI was 94+/-18ml/m(2), with a mean MRI RVEF of 58+/-27%. CONCLUSIONS: Cardiopulmonary bypass for repeat RVOT interventions can be avoided in selected patients with this newly available device. In combination with a wide range of prosthesis sizes it offers yet another important treatment option.     

Do valved stents compromise coronary flow?

OBJECTIVE: The aim of the present study is to evaluate a new self-expanding valved stent design for minimal invasive aortic valve implantation and its interference with coronary flow. METHODS: An equine pericardial valve mounted onto a self-expanding nitinol stent (3F Therapeutics trade mark, CA, USA), outer diameter 23 mm, was evaluated (A) in vitro in a dynamic pulsatile mock loop and (B) in vivo in six calves (75+/-2.5 kg). In four animals valve stents were implanted on-pump and in two animals off-pump after induction of ventricular fibrillation. Target site for deployment was the orthotopic aorta, over the native valves. In vivo assessment was performed with intracardiac (AcuNav) and intravascular ultrasound including leaflet motion, planimetric valve orifice and residual-coronary\sinus-stent-index (RCSSI, distance stent to aortic wall/coronary diameter) calculations, coronary blood flow characteristics, transvalvular gradient, regurgitation and paravalvular leaking, in combination with continuous cardiac output measures. Macroscopic analysis was performed at necropsy. RESULTS: Two-dimensional intracardiac ultrasound showed good leaflet motion, with full valvular opening and closing in five of six valves. Planimetric valve orifice was 1.75+/-0.4 cm(2). There were no signs of coronary flow impairment with an RCSSI of 1.8+/-1.2. The implanted valved stents showed a low transvalvular gradient of 5.3+/-3.9 mmHg (mean, peak-to-peak) on invasive measurements and 4.7+/-2.5 mmHg in two-dimensional intracardiac sonography. One of six valves showed mild to moderate regurgitation and one of six valves a minor to moderate paravalvular leak due to size mismatch. CONCLUSIONS: This new self-expanding valved stent design allows for on- and off-pump aortic valve implantation in the orthotopic aorta, over the native valves without interference of the coronary blood flow and excellent acute valve function in properly sized devices.     

The Cryopreserved Homograft Valve in the Pulmonary Position: Early Results and Technical Considerations

Since September, 1985, 20 patients have undergone implantation of a homograft valve in the pulmonary position (16 pulmonary, 4 aortic). There were 11 primary operations and 9 reoperations. In 7 of 11 primary operations the homograft valve was utilized as a composite conduit with a short Dacron extension. In four of five reoperations for a failed porcine valved conduit, a composite homograft conduit was used. Four patients underwent implantation of a free homograft in a previously repaired right ventricular outflow tract (RVOT). Age ranged from 15 days to 22 years. There was one operative death (5%), a seven-week-old infant with truncus arteriosus. Long-term follow-up ranges from 1 to 30 months. Clinical performance has been satisfactory in 18 of 19 patients. One patient undergoing free implantation of a pulmonary valve in the RVOT required replacement at 18 months with a porcine valve. In this patient, pulmonary insufficiency was caused by distortion of the annulus secondary to dilatation and pulmonary hypertension. Nine of 18 survivors do not require medication. Eleven of 18 have trivial to mild pulmonary insufficiency murmurs without symptomatology. The homograft valve is extremely useful in reconstruction of the right heart, however, early insufficiency murmurs have been noted. Distortion of the valve annulus may contribute to the early onset of a benign insufficiency murmur. Residual distal obstruction or pulmonary hypertension may be a contraindication to the use of a free homograft in the orthotopic position.     

Percutaneous valved stent implantation in the ascending aorta for the treatment of very high-risk aortic regurgitation: an animal study

Purpose

We investigated the effects of percutaneous valved stent implantation in the ascending aorta as an alternative treatment for aortic regurgitation in a canine model.

Materials and methods

A total of 16 healthy dogs weighing an average of 18.3 ± 2.1 kg were used for the establishment of animal models of chronic aortic regurgitation by percutaneous aortic valve perforation and balloon dilation. At 2 mo after successful model establishment, all experimental animals underwent valved stent implantation in the ascending aorta and then were followed up for 3 mo.

Results

Experimental models of chronic aortic regurgitation were successfully established in 10 dogs. Surviving dogs underwent successful valved stent implantation in the ascending aorta and were subsequently followed up for 3 mo. The level of instantaneous aortic regurgitation at 3-mo follow-up was significantly reduced compared with that before valved stent implantation (2.4 ± 0.9 versus 10.6 ± 2.1 mL/s, P < 0.05). The left ventricular ejection fraction was significantly increased (53.8 ± 4.2% versus 37.8 ± 3.7%, P < 0.05), and the left ventricular end-diastolic volume was also significantly reduced (30.3 ± 2.2 versus 40.1 ± 3.6 mL, P < 0.05). No paravalvular leak, stroke, atrioventricular block, or other complications occurred in dogs undergoing valved stent implantation.

Conclusions

Percutaneous valved stent implantation in the ascending aorta is feasible, effective, and safe as an alternative treatment for very high-risk aortic regurgitation in a canine model.     

Direct access valve replacement (DAVR) - are we entering a new era in cardiac surgery?

OBJECTIVE: This study validates the off-pump antegrade trans-ventricular route for ultrasound-guided direct access aortic valve replacement. Direct access aortic valve replacement using a transthoracic and valved stent-based approach offers numerous advantages over the remote access percutaneous approach and may one day provide an alternative treatment modality for aortic valve disease. METHODS: Valved stents were implanted off-pump in 17 pigs (72.10+/-8.4 kg) via the direct access transapical approach using a left-sided mini-thoracotomy and continuous ultrasonic and fluoroscopic guidance. Acute valved stent function was studied with intravascular and two-dimensional intracardiac ultrasound. The invasive valve gradient was assessed with pull-back pressure catheter. All valved stents were tested in vitro before insertion. Macroscopic analysis was performed at necropsy. RESULTS: In 11 of the 17 pigs, valved stents were delivered to the target site over the native aortic valve leaflets without interference of coronary blood flow and with good acute valve function. Three valved stents were deployed supra-annularly, two of those occluded the right coronary orifice and one the left coronary orifice, leading to fatal outcomes. Three valved stents dislodged into the left ventricle, one because of size-mismatch and two because of failure to unfold correctly. In 11 properly sized and deployed valved stents, two showed a moderate and one a severe paravalvular leak. CONCLUSIONS: Seventeen pigs underwent direct access valve replacement of the aortic valve with deployment of a valved stent into the native aorta. Eleven valves observed for an average 5-h period showed satisfactory, postimplantation valve function.     

Percutaneous aortic valve replacement: computed tomography scan after valved stent implantation in human cadaver hearts

Computed tomography scans were performed before and after aortic valve resection with consecutive implantation of a valved stent in human hearts with highly calcified aortic valves in situ (n = 2). This demonstrates that the valved stent shows better fitting in the annulus after removal of the native valve.     

具有防移位设计的可压缩性肺动脉支架瓣膜动物置入手术及体内测试

目的 探讨具有防移位设计的可压缩性肺动脉支架瓣膜的防移位效果.方法 将带瓣牛颈静脉缝在3个"Z"字型镍钛合金支架上,制作成喇叭口型肺动脉支架瓣膜.非体外循环下用推送器将其经右心室置入羊肺动脉瓣位置(n=6),分别于术后早期、术后2个月采用右心导管、心脏彩超、血流动力学测定、大体病理等方法评价置入瓣膜的位置和功能.结果 6只羊支架瓣膜均在正确位置释放.超声、右心导管造影以及血流动力学检查显示,术后早期、术后2个月置入瓣膜支架固定好,无移位,1例瓣膜收缩期跨瓣压差24 mm Hg,1例瓣膜轻度关闭不全,其他瓣膜功能良好.结论 喇叭口型支架有助于防止瓣膜移位.     

Pure aortic valve regurgitation due to congenital bicuspid valve--analysis of 7 cases and a report of 2 rare cases

The congenital bicuspid aortic valves usually become stenotic with severe calcification or regurgitant due to infective endocarditis (IE). However, pure aortic valve regurgitation without calcification or IE may be occurred. We report seven these cases out of 30 bicuspid valved patients who underwent aortic valve replacements. Pathological findings of these resected valves revealed neither calcium deposit nor findings of infection, but commonly showed myxoid degeneration. They were operated on at the mean age of 39, while those with calcified bicuspid aortic valves had an average age of 56. Two rare cases in whom an anomalous fibrous band on the larger cusp attached to the aortic wall were also reported.     

法乐四联症肺动脉瓣缺如综合征的外科治疗

手术治疗６例法乐四联症肺动脉瓣缺如综合征。除１例伴左肺动脉缺如者于术后１天死亡外，余５例恢复良好，经随访手术效果满意，作者认为对儿童型无呼吸道症状者可在３－４岁纠治，对婴幼型伴严重呼吸道症状必须早期手术治疗。     

碳化二亚胺交联去细胞猪肺动脉带瓣管道物理性能的研究

目的研究碳化二亚胺（carbodiimide,EDC）交联去细胞猪肺动脉带瓣管道体外的物理性能。方法在相对无菌条件下取得20个猪带瓣肺动脉,沿肺动脉瓣膜交界处纵向剪开分成3份（每份样本都由肺动脉管壁及其瓣膜组织组成）。将3份样本用抽签法随机分为3组：A组为对照组,为新鲜猪肺动脉带瓣管道样本,不再进一步处理;B组为去细胞组织样本,采用胰蛋白酶＋去污剂Triton X-100对猪带瓣肺动脉样本进行去细胞处理;C组为EDC交联去细胞组织样本,即在B组处理的基础上进一步行EDC交联处理。测试肺动脉组织含水量、厚度、抗张强度和热皱缩温度,评价所有样本的物理性能。结果胰蛋白酶＋去污剂能完全去除猪肺动脉带瓣管道组织的内膜层内皮细胞和管壁及瓣膜组织的细胞和部分基质成分,保留比较完整的纤维支架成份。与A组相比,B组肺动脉壁样本含水量增加（P=0.000）,肺动脉瓣膜含水量变化不明显,肺动脉壁（P=0.000）和瓣膜（P=0.000）的厚度减少、抗张强度下降（P〈0.01）、热皱缩温度无明显变化。与B组比较,C组肺动脉管壁样本含水量减少（P=0.000）,肺动脉瓣膜样本含水量变化不明显。肺动脉管壁和瓣膜样本的厚度变化不明显、抗张强度增加（P〈0.01）、热皱缩温度增加（P=0.000,0.000）。与A组相比,C组肺动脉壁和瓣膜含水量变化不明显,肺动脉壁和瓣膜的厚度减小（P=0.000,0.000）,抗张强度无明显差别,热皱缩温度增加（P=0.000,0.000）。结论 EDC交联去细胞方法能够加强去细胞肺动脉带瓣管道的抗张强度、降低去细胞肺动脉管壁的含水量。     

Gore-Tex片作单瓣重建右心室流出道的早、中期疗效

目的评价0.1mm厚的Gore-Tex片作肺动脉单瓣重建右心室流出道(RVOT)的早中期临床效果。方法2002年6月至2006年7月,对48例合并肺动脉狭窄或闭锁的先天性心脏病患者施行矫治手术,术中采用0.1mm厚的Gore-Tex片作肺动脉单瓣的Dacron血管片重建RVOT,其中包括法洛四联症合并肺动脉狭窄33例、型肺动脉闭锁8例、肺动脉瓣缺如3例,右心室双出口合并肺动脉狭窄2例,永存动脉干1例,完全型大动脉错位、室间隔缺损、肺动脉狭窄1例。结果本组无手术死亡。术后血氧饱和度达1.00,右心室/左心室收缩压比值0.22~0.65,右心室与左、右肺动脉压差<10mm Hg。所有患者(100%)均随访3~48个月,无死亡和并发症。彩色多普勒超声心动图检查提示:无肺动脉狭窄,肺动脉瓣轻度反流13例,中度反流5例,Gore-Tex膜具有活动功能40例。结论采用0.1mm厚的Gore-Tex片作单瓣重建RVOT,其早中期临床结果显示有较满意的血流动力学效果。     

Coronary flow obstruction in percutaneous aortic valve replacement. An in vitro study.

OBJECTIVE: Coronary flow obstruction is a serious complication reported in percutaneous aortic valve replacement. In an in vitro study of porcine hearts, the effects of valved stent implantation on coronary artery flow were studied with the native valve's leaflets intact and excised. METHODS: The right and left main coronary arteries of porcine hearts were dissected 20mm distal to the aortic root and directed into lengths of latex tubing leading to collection flasks. The ascending aorta was cut proximal to the brachiocephalic trunk, cannulated, and attached to a constant-head water supply. After steady flow was achieved, the flow rate from each coronary artery was measured. In Group A (n=10), a tubular pericardial valve sutured into a cylindrical, cobalt-nickel stent was deployed orthotopically using a valvuloplasty balloon catheter. In Group B (n=10), the native leaflets were removed before similar valve deployment. Coronary flow measurements were repeated post-implantation. RESULTS: In Group A, valve implantation resulted in a significant decrease in both left and right coronary flows. In Group B, no significant change in either right or left coronary flow was found after valve placement. CONCLUSION: Implantation of a percutaneous valved stent in the orthotopic position with the native valve in place causes coronary ostial obstruction. This problem highlights the need for modified stents that are designed for implantation in patients with non-retracted, fibrotic, or calcified leaflets.     

Hand-Made Valved Conduit with High-Porosity Knitted Graft and Glutaraldehyde-Treated Autologous Pericardial Trileaflet Valve

In 10 patients with various congenital heart defects requiring reconstruction of right ventricle to pulmonary artery continuity, a new hand-made valved conduit was introduced. To avoid late stenosis with peel formation of the graft, high-porosity Golaski knitted graft was chosen. The graft was sealed by fibrin glue, and autologous pericardium was treated with glutaraldehyde and used to construct a trileaflet valve inside the graft. This hand-made graft was pliable with good conformability. The valve function was found good in the intermediate follow-up in 8 patients. This composite valved conduit may be a good alternative to the xenograft valved conduit when allograft conduit is not available.