PTFE Patch Research Articles

Preliminary Results of PTFE Patch Saphenoplasty to Prevent Neovascularization Leading to Recurrent Varicose Veins

Objective: Recurrence is common after varicose vein surgery. Neovascularization may be one cause of recurrent veins. This was a study of PTFE patch saphenoplasty to try and prevent recurrent veins. Design and setting: Prospective cohort study of patients treated in a vascular surgical unit. Patients and interventions: Fifty patients having surgery for symptomatic long saphenous varicose veins (66 legs, 51 primary and 15 recurrent veins) had a PTFE patch sutured over the saphenous opening after flush saphenofemoral ligation. Main outcome measures: The rate of varicose vein recurrence and neovascularization 1 year after surgery were determined using clinical examination and venous duplex imaging. Results: Forty patients (80%) remained pleased with the results of their surgery. Recurrent veins were visible in 14 (21%) legs: 10 were principally due to neovascularization, two to sapheno-popliteal incompetence and two to an incompetent mid-thigh perforating vein. Three other legs had neovascularization but no recurrent veins. Both recurrent veins (47% versus 14%) and neovascularization (40% versus 14%) were significantly more common in patients having surgery for recurrent veins. Conclusions: PTFE patching was safe but did not abolish neovascularization. Neovascularization was the principal cause of recurrent veins in this study and perseverance with investigations into other barrier methods is worthwhile.

Surgery of the inferior vena cava for tumor-related obstruction

Kidney tumors and pheochromocytomas of the adrenal gland may extend into the inferior vena cava (IVC) or even the right atrium. In these cases, curative surgery frequently requires partial resection of the IVC. From 1992 to 1995, 8 patients (6 kidney tumors, 2 pheochromocytomas of the adrenal gland) underwent tumor surgery with concomitant IVC resection. Four patients had tumor growth into the right atrium. Surgery was carried out during hypothermic circulatory arrest (n=4) using veno-venous bypass from the IVC to the jugular vein (n=2), or by simply clamping the IVC (n=2). In 6 patients the IVC was reconstructed using a PTFE prosthesis (n=2) or patch (n=4), in 2 patients the IVC was closed by a running suture only. All patients were discharged home 10–23 days after surgery (mean 13 days). During the follow-up (mean 23 months), 6 patients were in good clinical condition and without evidence of tumor recurrence up to 44 months after surgery and 2 patients died of metastases (16 and 17 months). Refinements of surgical techniques combined with a multidisciplinary approach involving vascular surgeons, cardiac surgeons, and urologists allow successful treatment of advanced tumor stages with IVC involvement, formerly considered a contraindication for surgery. The aggressive surgical approach is warranted not only for relief of symptoms, and acceptable survival rates can be achieved; even cure of the disease is possible.

SELECTIVE ANTICOAGULATION WITH ACTIVE-SITE BLOCKED FACTOR IXa IN SYNTHETIC PATCH VASCULAR REPAIR RESULTS IN DECREASED BLOOD LOSS AND OPERATIVE TIME

Heparin has been the mainstay of anti thrombic therapy in arterial repair procedures. With increasing use of synthetic patch angioplasty (polytetrafluoroethylene [PTFE] or Dacron, Medical Products, Flagstaff, AZ) to improve long-term patency and limit aneurysmal dilation, however, the use of heparin has been associated with excessive needle hole bleeding, resulting in time delay in the operating room to achieve hemostasis, as well as clinically significant blood loss. Because of the multiple sites of action of heparin in the coagulation cascade, both intravascular (desired effect) and extravascular (untoward side effect) hemostasis are impaired. The authors therefore tested the hypothesis that selective inhibition of intravascular coagulation, without significant impairment of extravascular hemostasis, would prevent clotting intraluminally while preserving hemostasis at the suture line of the patch graft. The unique position of factor IX/IXa in the coagulation cascade renders its inhibition an ideal target in this setting. The authors prepared active site blocked factor IXa (IXai) using dansyl-Glu-Gly-Arg chloromethylketone, and tested this hypothesis in a New Zealand rabbit aortotomy model with PTFE patch closure using either heparin (25 i.u./kg; n = 16) or IXai (300 micrograms/kg; n = 21). The infrarenal aorta was identified and isolated, the anti coagulant infused, aortic cross clamp placed, and aortotomy repaired with a 2 x 6 mm PTFE patch. After cross-clamp removal, blood loss was measured and time to hemostasis was recorded. Compared with heparin, IXai resulted in significantly reduce blood loss (6.97 +/- 4.4 g vs 2.72 +/- 2.51 g, respectively, p < 0.008), and time to hemostasis (2.94 +/- 0.77 min vs 2.0 +/- 0.63 min, respectively, p < 0.003). To assess long-term patency and thrombosis, 12 rabbits (given heparin; n = 6 and IXai; n = 6) were observed for up to 2 months post-operatively. No differences were observed between rabbits treated with heparin or IXai; 100% of the grafts were patent with no differences in degree of intimal hyperplasia by histologic analysis. Together, these data suggest that use of IXai in PTFE vascular repair will safely allow realization of the benefits of long-term patency and decreased aneurysmal dilatation, while eliminating the intraoperative morbidity of needle hole bleeding.

Physical properties and testing methods for PTFE cardiovascular patches.

Patching after endarterectomy, especially carotid artery surgery, is a common procedure to repair and close the surgical site. Both synthetic and natural materials can be used, but saphenous vein is preferred due to its greater long-term patency. In situations where it is not possible to use the saphenous vein, both Dacron and expanded polytetrafluoroethylene (ePTFE) patches have been used successfully. Expanded PTFE patches are readily available, soft and pliable, have excellent biocompatibility and do not require preclotting prior to implantation. Comparison of two types of ePTFE patches versus natural vessel show that they have more than adequate properties for their intended use.

Laparoscopic hernioplasty update.

The Toy-Smoot laparoscopic hernioplasty has been performed on 75 patients with a total of 83 hernioplasties over the past 20 months. Sixty-nine patients were male and six were female. The age range was 20 to 75 years with an average age of 51.5 years. Twelve of the patients had bilateral hernias repaired: 55 direct hernias, 16 indirect hernias, and 5 pantaloon hernias. Eleven of the repairs were for recurrent hernias. The procedure was performed under general anesthesia. The abdomen was insufflated with carbon dioxide, establishing the pneumoperitoneum. Three 11 mm trocars were inserted, the first via the umbilicus, into which the 0 degrees endoscope was inserted. Two additional trocars were inserted at the level of the umbilicus at the anterior axillary lines. The hernia sacs were left in situ. The medial umbilical ligament was dissected medially, so as to identify directly the pubic tubercle and the Cooper's ligament. An expanded PTFE soft tissue patch, 1 mm thick and 7.5 x 10 cm in size, was attached to the Nanticoke Endo-patch spreader and introduced via the contralateral trocar and positioned over the hernia defect. The Endopath EMS stapler was then used to secure the PTFE patch over the hernia defect. This required secure anatomical fixation to the transversalis fascia anteriorly and laterally, the pubic tubercle, and the posterior rectus sheath, medially, Cooper's ligament, posteromedially, and the endoabdominal fascia, posterolaterally. There were a total of seven different complications, one major, which was a bladder injury that required an open repair of the bladder and then an open, conventional hernioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Laparoscopic Repair of Diaphragmatic Hernia

A laparoscopic diaphragmatic hernia repair was done using a left subcostal trocar insertion with a total of three ports. The laparoscopic technique was illustrated. Chest x-rays pre-op and post-op were taken. The material used in the repair was 0-Chromic sutures and expanded PTFE patch. The hospital stay was minimal (24h). The patient symptomatology was improved almost immediately. The use of a laparoscopic approach for accessible diaphragmatic hernias is the method of choice. The use of an expanded PTFE patch (with its properties to incorporate the diaphragm) adds strength to the remaining diaphragm.

The Suitability of Expanded PTFE for Carotid Patch Angioplasty

From June 1985 to December 1988, 175 consecutive patients underwent 204 carotid endarterectomies with routine use of expanded PTFE patch angioplasty. Two patients (1%) suffered strokes and there were no transient ischemic attacks or deaths in the immediate postoperative period. All carotid endarterectomies were performed with an intraluminal shunt without cerebral monitoring. The indications for carotid endarterectomy were symptoms (83% of patients) or no symptoms of internal carotid artery atherosclerotic stenoses (12.7% of patients). Neurological assessment, Doppler and real-time ultrasound were performed at six months, twelve months and then annually. Over the follow-up period there were one asymptomatic occlusion and two high grade symptomatic stenoses which required reoperation.

Management of Pediatric Visceral Arterial and Aortic Coarctation

Two unusual pediatric vascular problems have been managed surgically. The first patient is a five-and-a half-year old girl who presented with renal artery stenosis and aneurysm and renovascular hypertension. This was treated by excision of the aneurysm and reimplantation of the right renal artery. The second patient is a two-year old girl with atresia of the abdominal aorta, superior mesenteric artery (SMA) and both renal arteries. She was treated by PTFE patch graft angioplasty of the aorta, SMA reimplantation and bilateral aorto-renal autogenous saphenous vein bypass.

Surgical Treatment of Supraventricular Arrhythmias Results in 67 Patients

Over 6 years, recurrent drug-refractory supraventricular arrhythmias were treated by electrophysiologically guided surgical procedures in 67 patients. There were 57 patients, age 10-72 years, with accessory pathways who had 61 operations. The perioperative mortality rate was 3.5%, with deaths occurring in two patients with complex problems. Four patients with multiple but one or more silent accessory pathways had successful reoperation, and modified surgical technique has eliminated this problem. All patients are free of arrhythmias 2-70 months after operation. The survival and primary cure rates were 100% for 36 patients with solitary accessory pathways. Eight patients, age 10-53 years, were operated on for atrial focal tachycardia. Right atrial cryothermic lesions without excision or cardiopulmonary bypass were used in four patients: local excision was used in two patients and combined procedures were used in two patients. Because of recurrence in two of four patients treated by isolated cryoablation, a new technique was applied subsequently to one of these patients and two other patients: wide atrial excision and PTFE patch replacement during cardiopulmonary bypass. All patients are free of arrhythmias at a follow-up of 9-72 months. Intractable atrial flutter or fibrillation occurred in 11 patients who had 15 attempts at transvenous A-V node electroshock ablation. In three patients in whom this failed, subsequent open cryoablation of the A-V node during cardiopulmonary bypass and epicardial pacemaker implantation were performed successfully. Two patients had A-V nodal modification for control of A-V nodal re-entry tachycardia: one patient with cryothermia at the time of ablation of atrial focal tachycardia and the other patient with sharp dissection at the time of accessory pathway division. Of the initial 67 patients, 65 (97%) survived operation and all were cured of their presenting arrhythmia. Surgery for drug-refractory supraventricular arrhythmias is safe and effective in selected cases.

The rationale for patch-graft angioplasty after carotid endarterectomy: early and long-term follow-up.

A prospective study was undertaken in March 1980, at the Vascular Surgery Department of the Padua University, Medical School, to establish whether patch graft angioplasty is useful in preventing restenosis after carotid endarterectomy (CE). Seventy-four patients underwent 86 CE (bilateral in 12 cases) for atherosclerotic disease involving the carotid bifurcation. Thirty-eight (51.4%) patients presented TIA's or non hemispheric symptoms of cerebrovascular insufficiency; 30 (40.5%) were asymptomatic and 6 (8.1%) had partial nonprogressing or fixed strokes. All operations were performed under general anesthesia, with pharmacologic hypertension and systemic heparinization; in all cases, continuous EEG monitoring and 'stump pressure' measurement were employed. The operation was performed without a temporary intraluminal shunt in the patients showing tolerance to carotid clamping. The protection of the shunt was required only in patients with EEG monitoring changes (17). All carotid arteriotomies were extended into the internal carotid artery to overpass the end of the endarterectomy. Overpass was also used in the proximal edge of the arteriotomy, in the common carotid artery. The distal intima was never fixed with stitches and the arteriotomy was routinely closed with a PTFE patch graft angioplasty. Early results of cerebral protection were excellent. No patient presented permanent or transient postoperative neurological problems and no patient died in the postoperative period for causes related to the operation. This is substantiated by results we achieved during the period 1970-1979 in 192 patients, when all carotid endarterectomies were routinely performed without a shunt, with figures of 2.5% of postoperative stroke and 1.5% of mortality. Longterm follow-up (from 6 to 36 months) was completed in 51 patients (60 operations).(ABSTRACT TRUNCATED AT 250 WORDS)