Experience with the modified Blalock-Taussig operation using polytetrafluoroethylene (Impra) grafts.

Between June 1978 and January 1982, 115 patients underwent 122 subclavian artery-pulmonary artery shunts using polytetrafluoroethylene (PTFE Impra) grafts. Forty-six of the patients had a ductus dependent pulmonary circulation, the patency of which was maintained by an infusion of prostaglandin E2 in 29 cases. There were nine hospital deaths, four of which were related to shunt failure. Five patients underwent a second shunt procedure within one week of the first. There were two cases of late graft occlusion. Twelve shunts were considered to have failed. The actuarial estimate of shunt patency was 90% (+/- 3%) at two years for all patients and 74% (+/- 10%) for neonates. There was no statistically significant difference in two year shunt patency between 4 mm grafts (88 +/- 5%) and 6 mm grafts (96 +/- 3%). The modified Blalock shunt using a PTFE graft is an effective pulmonary-systemic shunt with a good short term patency.     

Operative outcome and intermediate term follow-up of neonatal Blalock-Taussig shunts.

BACKGROUND: The neonatal age group is considered to be one of the important risk factors for perioperative morbidity and mortality as well as poor long-term patency following Blalock-Taussig shunts. METHODS AND RESULTS: Out of a total of 190 patients who underwent Blalock-Taussig shunts in our institute between July 1998 and July 2000, 20 patients were aged less than 30 days and this neonatal cohort was studied retrospectively. The mean age was 18+/-11 days (range: 3-30 days). The mean weight of the babies was 3.1+/-0.7 kg, the smallest weighed 2.1 kg. The cardiac anatomy was tetralogy of Fallot with pulmonary atresia in 6, pulmonary atresia with intact ventricular septum in 3, tricuspid atresia in 5 and complex single ventricle physiology in the rest. All patients were deeply cyanotic and preoperative prostaglandin E1 was needed in 10 patients to ensure ductal patency and maintain oxygen saturations prior to the shunt operation. The mean hilar right and left pulmonary artery sizes were 3.99+/-0.44 mm and 3.69+/-0.79 mm, respectively. Three patients (15%) had significant stenosis at the site of duct insertion. The shunts were accomplished with 3.5 mm polytetrafluoroethylene grafts in 7 patients (35%) and 4 mm in the rest. The mean duration of mechanical ventilation was 2.0+/-2.83 days, one patient who developed bronchopneumonia needed prolonged ventilation for 14 days. The mean intensive care unit stay was 4.79+/-2.66 days. The mean hospital stay was 11.7+/-6.4 days. Five patients who developed sepsis stayed beyond 14 days. There were 3 deaths (immediate post-operative shock and possibly shunt malfunction in 1, bronchopneumonia in 1 and late shunt thrombosis at 3 months in 1). Two patients had late shunt block, one of those mentioned above and the other at 3 months secondary to infective endarteritis of the right pulmonary artery. All these infants received 4 mm grafts. All the 3.5 mm grafts were patent at follow-up. Seventeen patients were alive and well at follow-up (mean: 9 months, range: 3-21 months) with a mean resting systemic oxygen saturation of 77% (66%-95%). CONCLUSIONS: The overall shunt patency rate after neonatal Blalock-Taussig shunt is about 80% on intermediate term follow-up. A smaller graft size (3.5 mm) does not appear to be an incremental risk factor for shunt blockade and operative mortality.     

Extraanatomic bypass in the treatment of prosthetic vascular graft infection manifesting in the groin

BACKGROUND: Infection of an alloplastic vascular graft is a serious complication and often involves the groin. We propose a therapeutic concept using extraanatomic bypass to avoid the septic groin in case of an infected alloplastic vascular reconstruction. PATIENTS AND METHODS: The course of 25 patients (18 men, 7 women, mean age 61 years) with a grade III inguinal infection following placement of an aortic or femoro-distal synthetic graft made of Dacron or PTFE was analysed. The treatment consisted of excision of the infected graft material and extraanatomic reconstruction with ringed PTFE grafts in all patients. Mean follow-up after the extraanatomic procedure was 21 months (1-91 months). RESULTS: Direct surgical exploration definitely secured graft infection in almost three-quarters of the cases. The most common organism isolated was Staphylococcus aureus (13/22 = 59%). At the time of infection 60% of the patients had critical limb ischemia necessitating vascular reconstruction simultaneously with total or partial excision of the infected graft. Complications of the extraanatomic bypass occurred in 7 cases (overall morbidity 28%). Postoperatively, one patient required major amputation. Hospital mortality was 8%. Primary patency and secondary patency rates of extraanatomic grafts amounted to 78.0% (+/- 10.0 SD) and 84.1% (+/- 8.7 SD) respectively after two years. Limb salvage rated 78.4% (+/- 11.6 SD) after 2 years, the 2-year-survival rate was 73.8% (+/- 9.3 SD). CONCLUSIONS: According to the favourable long-term limb salvage and survival rates, we support simultaneous vascular reconstruction by extraanatomic bypass and explanation of the infected graft material in case of grade III inguinal infection of alloplastic vascular reconstructions.     

Early and late results of the modified Waterston shunt with PTFE grafts for palliation of complex congenital cyanotic heart disease in neonates.

During a 12 year period from 1978 to 1989, 35 infants under 4 weeks of age underwent palliative surgery for complex congenital cyanotic heart disease with a short (1-1.5 cm) PTFE graft between the ascending aorta and the right pulmonary artery (modified Waterston shunt). Twenty-three infants had pulmonary atresia and 14 had severe pulmonary stenosis. Underlying cardiac lesions were tetralogy of Fallot (n = 11), single ventricle (n = 7), transposition complexes (n = 6), and intact ventricular septum and hypoplastic right heart syndrome (n = 13). There were 4 early deaths (10.7%) in the entire series, 2 of which were shunt related. Three of the 4 occurred during our initial experience with this shunt in 1978 and 1979. They led to the modified Waterston shunt being abandoned for 3 years in favor of other shunt procedures. Since 1983 one early death occurred in 28 infants (3.5% mortality) with no death in the latest 26 patients. All patients were followed up between 6 and 108 months. There were 4 late deaths, one of which was shunt related. We observed a significant difference in the shunt patency rate between 4 and 5 mm grafts: palliation was adequate after 2 years in 52% of the patients when a 4 mm graft was used and in 89% of the 5 mm graft group (p less than 0.005). Reshunting was necessary in 7 infants between 5 and 60 months after primary surgery. Recatheterization was performed in 17 infants for suspected shunt failure (n = 6) or diagnostic reasons (n = 11).(ABSTRACT TRUNCATED AT 250 WORDS)     

Complete arterial revascularization using T-graft technique in diabetics with coronary three-vessel disease

BACKGROUND: Coronary revascularization using exclusively arterial grafts holds the promise of improved long-term patency. The T-graft approach achieves this goal with only two arterial grafts in coronary 3-vessel disease. Arterial grafts in diabetics, however, exhibit more frequently atherosclerotic wall abnormalities, and higher levels of endothelin-1 were found in diabetic arterial grafts, which may be associated with a higher incidence of vasoconstriction. The objective of this prospective study was to compare functional und angiographic parameters of arterial T-grafts in diabetics and nondiabetics. METHODS: Coronary angiography was performed consecutively in 20 patients with insulin-dependent diabetes mellitus (IDDM), 20 patients with non-insulin-dependent diabetes mellitus (NIDDM), and 100 non-diabetics one week after complete arterial revascularization with T-grafts. Graft patency was assessed, and the diameter of the proximal left internal mammary artery (IMA) graft was measured using quantitative coronary analysis. Absolute flow volume in the proximal left IMA was measured using the flow-wire technique at baseline and after an adenosine injection into the graft to induce maximal hyperemia. Coronary flow reserve (CFR) was calculated as the ratio of maximal to baseline flow. RESULTS: There was no difference between patients with IDDM, patients with NIDDM and non-diabetics with respect to patency (98.3% vs. 98.8% vs. 97,8%, n.s.), graft lumen diameter (3.42 +/- 0.48 vs. 3.36 +/- 0.50 vs. 3.38 +/- 0.41 mm, n.s.), baseline flow (78.4 +/- 34.3 vs. 83.1 +/- 36.6 vs. 81.5 +/- 39.0 ml/min, n.s.), and CFR (1.85 +/- 0.37 vs. 1.89 +/- 0.44 vs. 1.90 +/- 0.40, n.s.). CONCLUSION: Baseline parameters (graft diameter and quantitative graft flow), patency and CFR are identical in diabetics and non-diabetics. Our results suggest that diabetic patients with coronary 3-vessel disease take comparable profit from complete arterial revascularization using the T-graft technique as non-diabetics.     

Percutaneous laser-facilitated thrombectomy: an innovative, easily applied, and effective therapeutic option for recanalization of acute and subacute thrombotic hemodialysis shunt occlusions.

PURPOSE: To report our experience with excimer laser-facilitated recanalization of acute and subacute thrombotic occlusions of hemodialysis shunts. METHODS: Twenty-one patients (16 women; mean age 54+/-19 years, range 31-76) presented with acute and subacute thrombotic occlusions of their hemodialysis shunts (4 Cimino, 17 prosthetic; 18 forearm, 3 upper arm); mean occlusion time was 4.1+/-3 days (range 1-14), and the thrombotic occlusion measured a mean 17.4+/-9 cm (range 5-27). Fresh thrombus was observed in addition to the total shunt occlusion in all cases. All patients were treated initially with a pulsed ultraviolet (308-nm) excimer laser. Eighteen (85.7%) patients received adjunctive local thrombolysis for treatment of residual thrombus. Nineteen (90.5%) patients underwent angioplasty of the underlying anastomotic stenosis. RESULTS: The angiographic occlusion was reduced from 100% to 63%+/-28% after laser treatment and to 36%+/-18% after 1 hour of thrombolytic therapy (20 mg tissue plasminogen activator). TIMI flow increased significantly from grade 0 to 2.7+/-0.5 following laser ablation (p<0.001) and to 3.0+/-0.2 upon completion of the angioplasty procedure (p>0.001 versus baseline). The immediate procedural success was 95.2% (20/21). Detectable thrombotic embolization and laser-related complications were not observed in any case. Primary patency was 85%; 3 patients had abnormal Doppler flow within 6 weeks and underwent reintervention (secondary patency 100%). All successfully treated shunts were usable for further dialysis at the 6-week follow-up. CONCLUSION: Percutaneous excimer laser-facilitated thrombus vaporization is safe and effective for recanalization of acute and subacute thrombotic occlusions of hemodialysis shunts.     

Femorotibial bypass grafting for lower limb ischaemia

The results of 305 femorotibial bypass grafts performed in 246 patients are presented. Of these operations 246 were primary and 58 secondary or tertiary. A total of 66 diabetic patients were in the series. An autogenous saphenous vein graft was employed in 196 primary operations, the other grafts used being PTFE, human umbilical cord vein graft, venous allograft and knitted dacron velour graft. Hospital mortality was 8 patients (2.6%), while late mortality was 73 patients, 39 of them having had patent grafts. There were 89 (29.2%) immediate or early hospital failures. Two-hundred-sixteen grafts were followed for a mean observation time of 62.3 +/- 5.7 months. The cumulative patencies were analyzed using the life-table method. One, five, and ten year overall patencies for saphenous vein grafts as indicated by claudication were 73%, 53% and 35%, respectively. In rest pain, the patency rates were 62%, 46% and 40% at similar intervals. In impending gangrene the patencies were 43%, 35% and 20%, respectively. The patencies for arterial substitutes were generally poor, i.e., 35% and 15% at one and five years. None of the graft substitutes were followed for up to ten years. Diabetic patients had a significantly lower patency rate than nondiabetics (p = 0.002). The impact was remarkable if impending gangrene co-existed. In all these situations the early graft failure ensued. Both the run-off and inflow status affected the patency rates. This was significantly lower (p = 0.001) when only one distal branch was visualized in angiography.     

Membrane-covered stents: a new treatment strategy for saphenous vein graft lesions.

The restenosis rate after stenting of lesions in aortocoronary venous bypass grafts still has to be considered unsatisfactorily high. We investigated a new stent design characterized by an expandable polytetrafluorethylene (PTFE) membrane in between two layers of struts. Five consecutive male patients (age 70 +/- 6 years) were followed prospectively who presented with at least two de novo lesions in different grafts 13 +/- 3 years after bypass surgery. A total of 11 lesions were treated located in grafts anastomosed to the circumflex (n = 3), to the LAD (n = 7), and to the right coronary artery (n = 1). Within the same procedure, every patient received membrane-covered stents (n = 6) and conventional stents (n = 5) in either of their lesions. All patients underwent successful interventions. The minimal luminal diameter increased from 1.0 +/- 0.5 to 2.9 +/- 0.6 mm in lesions treated by the membrane-covered stents and from 0.8 +/- 0.4 to 2.4 +/- 0.7 mm in the lesions treated by conventional stents. During follow-up, four out of five patients required angioplasty for in-stent restenosis of lesions covered by a conventional stent, whereas no patient underwent revascularization for a lesion treated by a membrane-covered device. The mean minimal luminal diameter of lesions covered by a conventional stent decreased by 42% to 1.4 +/- 0.6 mm; the mean minimal luminal diameter of the lesions treated by a stent graft declined by 9% to 2.8 +/- 0.6 mm (P < 0.05). This series of intraindividual comparisons suggests that membrane-covered stents may have the power to reduce in-stent restenosis in obstructed aortocoronary venous bypass grafts.     

Pulmonary hemodynamics and maintenance of palliation following polytetrafluoroethylene shunts for cyanotic congenital heart disease

Subclavian-to-pulmonary artery anastomoses with interposition polytetrafluoroethylene (PTFE) conduits provide excellent early palliation for many forms of cyanotic heart disease. It is important to assess whether patients with this condition maintain adequate arterial oxygenation without developing pulmonary artery distortion or hypertension. From October, 1980, to December, 1982, 29 PTFE shunts were performed. There were no hospital deaths or shunt failures. Catheterization was performed in 14 patients from 2 months to 2.5 years (mean 13.4 months) following operation. All shunts were patent. Arterial Po2 at the late study ranged from 33 to 96 torr (mean 57.1 +/- 17.3 torr) and was not significantly different from values obtained before hospital discharge at the time of the shunt procedure (mean 47.6 +/- 5.9 torr). Only one patient demonstrated moderate pulmonary hypertension (44/25 mm Hg), believed to be secondary to ventricular dysfunction. No patient demonstrated pulmonary artery distortion or kinking, and none required a second shunt because of inadequacy of the original procedure. The results in these patients, as well as the continued excellent clinical course of the patients not as yet recatheterized, have prompted us to use this shunt as our procedure of choice in neonates.     

Transthoracic echocardiography using second harmonic imaging with Valsalva manoeuvre for the detection of right to left shunts.

AIMS: To assess transthoracic echocardiography (TTE) using second harmonic imaging with Valsalva manoeuvre compared to transesophageal echocardiography (TEE) for the diagnosis of right to left cardiac and pulmonary shunts. METHODS AND RESULTS: One hundred and ten patients referred for TEE underwent TTE with bubble contrast. Bubbles in the left atrium within three cardiac cycles were considered diagnostic for a patent foramen ovale (PFO) and later as a pulmonary shunt. Greater than 20 bubbles in the left atrium was considered a large shunt and less than 20 a small shunt. TEE was performed immediately afterwards and read blinded to the TTE results. Pick-up rates were similar with 19 TEE positive (13 PFO) and 18 TTE positive (14 PFO) patients. There were five TEE positive/TTE negative cases who had significantly poorer TTE image quality score (2.7 +/- 0.8 vs 1.9 +/- 0.6, p < 0.05). There were six TEE negative/TTE positive cases, two cases requiring Valsalva manoeuvre to become positive. The Valsalva manoeuvre significantly increased the number of bubbles shunting (10 +/- 11 vs 20 +/- 19, p < 0.005). CONCLUSION: TTE with Valsalva manoeuvre is as good as TEE in diagnosing shunts. Valsalva manoeuvre increases the size of shunt. Both techniques produce false negative results.     

Permeability of aortocoronary bypass after 6 months. A multicenter French study

The EPPAC (Etude de la perméabilité des pontages aortocoronaires) is a randomised prospective (18 centres) double blind trial designed to compare the patency of coronary bypass grafts in two groups of coronary patients after surgery: one group treated with oral vitamin-K antagonists and placebo (n = 196, age 57 +/- 5 years, 2.09 grafts/patient) and the other group with vitamin-K antagonists and dipyridamole (n = 182, age 56 +/- 6 years, 1.99 grafts/patient), the principal criterion of evaluation being the patency of the grafts at coronary angiography performed 6 months after surgery, interpreted by two independent observers. Of the 469 patients included (average ejection fraction 59.5 +/- 2.2%), 378 underwent the control coronary angiography at the 6th month and 773 saphenous vein grafts were evaluated. At the end of the study, there were 12 deaths, 10 due to perioperative myocardial infarction, and 24 nonlethal myocardial infarctions. The frequency of occlusion of at least one graft per patient was 18.2%, the patency of the graft at the distal anastomosis was 89.9%. The following factors played a major role: the cardiological center: the occlusion rate per patient ranged from 7.1 to 57.1% and per anastomosis from 2.8 to 28.6%; the internal diameter of the artery grafted: when 2 mm or more, the occlusion rate was 17.6% compared with 42.3% (p less than 0.001); the technique used for distal anastomosis: 9.2% of grafts with single outflow sites occluded, compared with 4.3% of grafts with multiple outflow sites. Early occlusion of saphenous vein aorto-coronary grafts is the main problem of this form of therapy and the addition of dipyridamole to oral anticoagulants does not seem to reinforce the anti-thrombotic effect at 6 months after surgery.     

Patency and clinical outcomes of transjugular intrahepatic portosystemic shunt with polytetrafluoroethylene-covered stents versus bare stents: a meta-analysis

Background and Aim: Transjugular intrahepatic portosystemic shunt (TIPS) with polytetrafluoroethylene‐(PTFE)‐covered stent has been increasingly used for patients with complications of portal hypertension. It is still debated whether the new endoprostheses will improve some clinical outcomes (except for shunt patency) compared to the bare stents. The aims of our meta‐analysis were to explore the patency and clinical outcomes of TIPS with PTFE‐covered stent‐grafts versus bare stents. Methods: Pertinent studies were retrieved through PubMed (1950–2010), MEDLINE (1950–2010), and reference lists of key articles. Outcome measures were primary patency, risk of encephalopathy and survival. Time‐to‐event data analysis was used to calculate the overall hazard ratios (HR). Results: Six studies were identified including a total of 1275 patients (346 TIPS with PTFE‐covered stent‐grafts and 929 TIPS with bare stents). Pooled shunt patency data from four eligible studies suggested a significant improvement of primary patency in patients who were treated with PTFE‐covered stent‐grafts (HR = 0.28, 95% confidence interval [CI] 0.20–0.35). Pooled encephalopathy data from three eligible studies suggested a significant reduction of risk in the PTFE‐covered group (HR = 0.65, 95%CI 0.45–0.86). Pooled survival data from four eligible studies also suggested a significant decrease of mortality in the PTFE‐covered group (HR = 0.76, 95%CI 0.58–0.94). No statistical heterogeneity was observed between studies for either outcome. Conclusions: This meta‐analysis shows that the use of PTFE‐covered stent‐grafts clearly improves shunt patency without increasing the risk of hepatic encephalopathy and with a trend towards better survival.     

Improving the quality of coronary bypass surgery with intraoperative angiography: validation of a new technique.

OBJECTIVES: We report a comprehensive assessment and validation of a new intraoperative angiography technique. BACKGROUND: Technical problems at the site of the distal anastomosis compromise an underappreciated proportion of coronary bypass grafts. The absence of a systematic, validated technique to verify graft patency in the operating room represents a significant breach in quality assurance. METHODS: Fluorescent indocyanine green (ICG) dye is excited with dispersed laser light to create an angiographic depiction of the graft, native vessel, and anastomosis. One-hundred twenty patients underwent ICG angiography. Angiograms were reviewed for reliability and validity studies. RESULTS: A total of 348 coronary bypass grafts were studied. Each ICG angiogram took 2.2 +/- 1.1 min to perform. The ICG angiography found 4.2% of patients had significant graft problems requiring major revision. Quality of visualization was rated according to a seven-point Likert scale (1 = worst, 7 = best). Among conduits, saphenous veins were best visualized (mean score +/- standard deviation), 6.4 +/- 1.5 versus 5.5 +/- 1.9 for internal mammary arteries and 4.4 +/- 2.3 for radial arteries (p = 0.02). Location of distal anastomosis did not influence quality of visualization. There was high inter-rater reliability for graft revision (kappa = 1.0) and graft patency (kappa = 0.97) between surgeons. Sensitivity and specificity of the ICG angiograms for graft stenosis >50% was 100% among 22 grafts also studied with X-ray angiography. CONCLUSIONS: Information from ICG angiograms led to graft revisions for technical problems in 4.2% of patients that would have otherwise gone unrecognized. Intraoperative angiography is an emerging tool for improving the quality of coronary bypass surgery.     

Stenting of stenosed aortopulmonary collaterals and shunts for palliation of pulmonary atresia/ventricular septal defect.

Patients with unrepaired pulmonary artery atresia and ventricular septal defect (PA/VSD) depend on aortoplumonary collaterals and surgically created shunts for pulmonary blood flow. These vessels frequently develop stenoses with time, leading to hypoperfusion of lung segments and systemic hypoxemia. The purpose of this article is to describe catheter palliation of hypoxemic patients with PA/VSD who were not candidates for surgical repair. We present our experience with stent implantation for stenosis of aortopulmonary collaterals and shunts in these patients. Three patients with hypoplastic pulmonary arteries underwent stent placement in aortopulmonary collateral arteries (APCAs) or their shunts. Technical aspects of the interventional catheterization procedure are discussed in detail. Case 1 underwent placement of five stents in collateral vessels and one stent in the Blalock-Taussig shunt (BT) with dramatic increase in vessel size and improvement in saturations from 70% to 89%. Case 2 underwent placement of two overlapping stents in a collateral vessel with an increase in diameter of the collateral vessel from 2.3 to 6 mm and an improvement in saturation from 68% to 88%. Case 3 underwent placement of three overlapping stents in a BT shunt with an increase in diameter of the shunt from 2.2 to 6.6 mm and an improvement in saturation from 71% to 89%. All three patients had excellent clinical improvement and stable saturation at follow-up. Stent placement for maintaining patency of APCAs and aortopulmonary shunts is feasible and safe.     

"Over-the-wire" inversion saphenectomy: a simple, minimally invasive vein harvesting technique for arterial bypass.

PURPOSE: To examine the feasibility and clinical outcome of a novel, minimally invasive technique for harvesting the great saphenous vein (GSV) for use in peripheral arterial bypass surgery. METHODS: Between May 2001 through March 2003, 27 patients (15 men; mean age 71+/-10 years) underwent extremity bypass procedures for limb salvage (88%) or disabling claudication (12%) using the inversion technique to harvest the GSV. The veins were turned "inside out" using a unique catheter and guidewire system. With the endothelial surface exposed, valve leaflets were excised, and adherent thrombus was washed away. Veins were inverted again to turn the endothelial surface back inside the lumen for use as a bypass conduit. RESULTS: Inversion vein harvesting and arterial bypass were completed in 24 (89%) of 27 patients; 2 patients were treated with synthetic grafts because of small GSVs. Another patient was found after vein harvesting to have inadequate arterial outflow despite a good quality conduit. The average vein length was 45+/-10 cm; a mean 4+/-1 incisions were made, including those for arterial exposure. Incisions made to divide vein tributaries averaged 2 cm in length. Duration of vein harvesting was 25 minutes (range 5-80). Wound complications were minor (2 hematomas, 2 cases of erythema, 2 seromas). Of 6 grafts that occluded after 30 days, 5 involved small-diameter vein grafts (< 3.5 mm). At a mean 12 months, primary and assisted primary graft patency rates were 88% (14/16) and 94% (15/ 16), respectively, for grafts with minimum diameters > or = 4 mm versus 38% (3/8) primary patency for veins < 4 mm (n = 8, p < 0.001). The limb salvage rate was 92% (22/24). CONCLUSIONS: Over-the-wire inversion saphenectomy is a simple and reliable minimally invasive technique for arterial bypass. Incisions are small and cosmetically superior to those of the traditional long incision method. One-year follow-up suggests that grafts harvested by inversion technique have excellent durability when the minimum vein diameter is > or = 4 mm, as determined by preoperative vein mapping.     

聚四氟乙烯纳米化新型小口径人造血管及其通畅率研究

目的 研究应用内表面覆盖多壁碳纳米管（MWNT）的聚四氟乙烯（PTFE）新型人造血管（PTFE-MWNT）对提高血管通畅率、减轻内膜增生的影响.方法 将MWNTs通过羧酸化及氨基化处理,分别得到功能化的MWNTs-COOH和MWNTs-NH2,然后在PTFE血管内表面层层自组装制成PTFE-MWNT人造血管.动脉模型选用羊股动脉血管移植.16只成年公绵羊,两侧股动脉随机选用两种不同的人造血管.8只于术后3个月,另外8只于术后9个月取下双侧人造血管标本进行组织学分析.统计方法采用配对t检验.结果 PTFE-MWNT血管术后通畅率（87.5%）高于PTFE血管（62.5%）,内膜增生程度较PTFE血管轻,血管内皮形成速度要快于PTFE人造血管,血管壁内的炎细胞浸润较轻;而PTFE人造血管壁内主要是炎细胞浸润,细胞增殖程度高于PTFE-MWNT人造血管.结论 用多壁碳纳米管覆盖聚四氟乙烯的内表面制成的新型人造血管,可以提高移植血管通畅率,减轻内膜增生,提高小口径人造血管移植手术的长期效果.     

Elastic and thrombogenic properties for different vascular grafts and its influence on graft patency

In a sheep model elastic and thrombogenic properties for various vascular graft materials were studied using peroperative compliance measurements and Indium-111-oxine labeled platelets in vivo. It was found that the least thrombogenic arterial vascular substitute was the autologous vein while a significantly higher thrombogenicity was recorded for the polytetrafluoroethylene (PTFE) graft and the Chinese pure silk graft. The two latter grafts did not differ significantly in thrombogenicity except for that the silk graft revealed a significantly higher peak value for deposited platelets onto its surface than the PTFE graft. Compliance measurements at graft implantation revealed that both the silk and the vein grafts were more elastic than the PTFE graft. The two grafts did not differ in elasticity from each other significantly. Elasticity for all grafts increased during the first 10 weeks after implantation. There was a good correlation between elastic properties and graft patency for all tested graft materials. However, the silk graft with favourable elastic characteristics was found to have less favourable thrombogenic properties and is therefore in its present form not the ideal graft for small caliber artery reconstructions.     

Long-term patency of saphenous vein and left internal mammary artery grafts after coronary artery bypass surgery: results from a Department of Veterans Affairs Cooperative Study

OBJECTIVES: This study defined long-term patency of saphenous vein grafts (SVG) and internal mammary artery (IMA) grafts. BACKGROUND: This VA Cooperative Studies Trial defined 10-year SVG patency in 1,074 patients and left IMA patency in 457 patients undergoing coronary artery bypass grafting (CABG). METHODS: Patients underwent cardiac catheterizations at 1 week and 1, 3, 6, and 10 years after CABG. RESULTS: Patency at 10 years was 61% for SVGs compared with 85% for IMA grafts (p < 0.001). If a SVG or IMA graft was patent at 1 week, that graft had a 68% and 88% chance, respectively, of being patent at 10 years. The SVG patency to the left anterior descending artery (LAD) (69%) was better (p < 0.001) than to the right coronary artery (56%), or circumflex (58%). Recipient vessel size was a significant predictor of graft patency, in vessels >2.0 mm in diameter SVG patency was 88% versus 55% in vessels 2.0 mm in diameter.     

Laser-assisted angioplasty in the treatment of prosthetic graft stenosis.

Late failure of peripheral bypass grafts has been treated primarily by secondary reconstruction. Laser-assisted angioplasty is an optional therapy that the authors investigated in 28 prosthetic grafts over a two-year period. Twenty-five symptomatic patients with 28 peripheral prosthetic arterial bypass grafts (25 polytetrafluoroethylene [PTFE] grafts and 1 each of knitted Dacron, Teflon, and umbilical vein) demonstrated graft occlusion (25) or high-grade stenoses (3). All patients underwent standard laser-assisted angioplasty using a continuous wave Nd:YAG laser source and hybrid probe. Twenty-one grafts (75%) were successfully recanalized with adequate restoration of flow through the conduit. All 7 failures were in occluded PTFE grafts that presented with either recalcitrant lesions (5) or perforations (2) at the distal anastomoses. There have been 3 long-term failures (14%) to date in the successfully treated group, all in PTFE grafts. Two patients suffered recurrent thrombosis and 1 developed an inexplicable graft infection five months after laser treatment. Laser-assisted angioplasty appears to be a clinically viable alternative treatment for prosthetic graft stenosis and recanalization of grafts occluded at their distal anastomosis.     

Comparison of the rheologic parameters in left internal thoracic artery grafts with those in saphenous vein grafts.

BACKGROUND: Left internal thoracic artery (LITA) grafts have superior patency to saphenous vein grafts (SVG). Because shear stress augments the release of nitric oxide throughout the LITA endothelium, shear stress and shear rate in coronary artery bypass grafts (CABG) may play an important role in the higher patency, so the aim of the present study was to evaluate and compare the rheologic parameters in CABG using LITA and SVG. METHODS AND RESULTS: Rheologic examinations were done in 197 patients using a vacuum-suction glass tube viscometer after CABG surgery was completed. Shear stress and shear rate were calculated from the geometry of the graft, blood flow in the graft and blood viscosity. Of 197 patients, 177 underwent LITA grafting to the left anterior descending artery (LAD) and 160 had SVG anastomosis to coronary arteries. Mean wall shear stress in the LITA grafts to the LAD (13.8+/-1.0 dyne/cm2) was nearly 4-6-fold larger than that in the SVG grafts. Mean shear rate (559.1+/-57.0 s(-1)) of LITA-LAD grafts was approximately 2-3-fold higher than that of SVG. CONCLUSION: These results suggest that high wall shear stress and shear rate play an important role in the higher patency rate of LITA grafts.