Gore-Tex Tube Graft Research Articles

Cylinder mitral and tricuspid valve replacement in neonates and small children.

Atrioventricular valve replacement in small children is associated with high morbidity and mortality. There are no prostheses available with a diameter ˂15 mm. This study reports our initial experience with a cylinder valve for mitral and tricuspid valve replacement in infants and small children. Our cylinder valve was hand-made for patients requiring atrioventricuclar valve replacement with an annulus of <15 mm. A 12-mm Contegra valve was prepared and placed inside a 14-mm Gore-Tex tube graft and sutured on both extremities. Eight patients were included, with a median age of 6.9 months (range 1 day to 38 months). Four had mitral and 4 had tricuspid valve replacement. All implants were technically successful, with no significant regurgitation, no stenosis and no left ventricular outflow tract obstruction. There were 3 early deaths from low cardiac output, in patients with significant associated lesions (severe neonatal Ebstein's, pulmonary artery-intact ventricular septum, biventricular conversion from Norwood stage 1). Two patients required early reintervention: 1 for balloon dilatation for stenosis and 1 for reoperation for paravalvular leak. During follow-up, 2 patients had mitral valve replacement with a 16-mm mechanical valve at 9 and 20 months from the cylinder valve implantation. The remaining 2 patients are alive and well 2 years and 2 months after the procedure. Cylinder valve replacement of atrioventricular valves was feasible without any technical issues. It was successful in getting out of a difficult situation and allows for somatic growth and implantation of a reasonably-sized mechanical prosthesis on the annulus.

Acute Bilateral Lower Extremity Paralysis Secondary to Acute Thrombosis of an Infrarenal Abdominal Aortic Aneurysm

We present the case of a 64-year-old male who presented to the emergency department with bilateral limb ischemia and paralysis for approximately 1 hour. Computed tomographic angiography demonstrated occlusion of the infrarenal aorta beginning just above the patient’s known abdominal aortic aneurysm (AAA) and extending into both common iliac arteries. He was emergently treated via open repair of the AAA with a Gore-Tex tube graft, bilateral common iliac thrombectomies, and bilateral lower extremity four-compartment fasciotomies. Post-operatively, he had monophasic signals in both posterior tibial arteries, neither of which was present before the operation. During recovery, he developed an ileus but otherwise did not have complications. He was discharged to rehabilitation on post-operative day 15.

Right Ventricle-to-Pulmonary Artery Shunt in Pulmonary Atresia with a Ventricular Septal Defect: A Word of Caution.

The management of pulmonary atresia with a ventricular septal defect (PA/VSD) depends on the anatomy of the pulmonary artery or on the surgical strategy used at individual institutions. In our institution, we adopted a right ventricle-to-pulmonary artery (RV-PA) shunt in 2011 as a palliative procedure for PA/VSD to overcome the disadvantages of a Blalock-Taussig shunt. We evaluated the results of the RV-PA shunt as initial palliative surgery for PA/VSD. Thirteen patients with ductus-dependent PA/VSD from August 2011 to August 2015 were enrolled. The mean age at surgery was 17.9 ± 15.3 (range 5-60) days, and the mean body weight was 2.9 ± 0.6 (range 2.2-4.0) kg. A Gore-Tex tube graft was used in all patients. We retrospectively observed intra- and postoperative complications, early and late mortality, and palliation duration to definitive repair. Left pulmonary artery angioplasty was performed as a concomitant procedure in three patients. There were no early hospital mortalities, although two inter-stage deaths occurred 34 and 47days postoperatively: one patient died of aspiration and the other of right ventricular outflow tract (RVOT) pseudoaneurysm rupture. Two patients (15.4%) required the extracorporeal membrane oxygenation support postoperatively: one because of failure to wean from a bypass caused by persistent hypoxemia and the other because of sudden massive bleeding from the RVOT suture line in the intensive care unit 2 days postoperatively. These two patients underwent second-stage definitive repair successfully. Five patients (41.7%) required catheter intervention, for juxtaductal left pulmonary artery stenosis in three patients, right pulmonary artery stenosis in one, and shunt inflow stenosis in one. Two patients (15.4%) required re-operation because of shunt inflow stenosis and RVOT pseudoaneurysm, respectively. All patients who survived the RV-PA shunt underwent total correction at a mean interval of 13.1 months. A RV-PA shunt is an option for the initial palliation of ductus-dependent PA/VSD. Major complications can occur, including RVOT pseudoaneurysm, shunt inflow stenosis, persistent hypoxemia during the immediate postoperative period, and dehiscence of the shunt anastomosis site. Caution should be taken when performing the RV-PA shunt for palliation of PA/VSD.

Computational fluid dynamics characterization of blood flow in central aorta to pulmonary artery connections: importance of shunt angulation as a determinant of shear stress-induced thrombosis.

The central aortic shunt, consisting of a Gore-Tex (polytetrafluoroethylene) tube (graft) connecting the ascending aorta to the pulmonary artery, is a palliative operation for neonates with cyanotic congenital heart disease. These tubes often have an extended length, and therefore must be angulated to complete the connection to the posterior pulmonary arteries. Thrombosis of the graft is not uncommon and can be life-threatening. We have shown that a viscous fluid (such as blood) traversing a curve or bend in a small-caliber vessel or conduit can give rise to marked increases in wall shear stress, which is the major mechanical factor responsible for vascular thrombosis. Thus, the objective of this study was to use computational fluid dynamics to investigate whether wall shear stress (and shear rate) generated in angulated central aorta-to-pulmonary artery connections, invivo, can be of magnitude and distribution to initiate platelet activation/aggregation, ultimately leading to thrombus formation. Anatomical features required to construct the computer-simulated blood flow pathways were verified from angiograms of central aortic shunts in patients. For the modeled central aortic shunts, we found wall shear stresses of (80-200N/m(2)), with shear rates of (16,000-40,000/s), at sites of even modest curvature, to be high enough to cause platelet-mediated shunt thrombosis. The corresponding energy losses for the fluid transitions through the aorta-to-pulmonary connections constituted (70%) of the incoming flow's mechanical energy. The associated velocity fields within these shunts exhibited vortices, eddies, and flow stagnation/recirculation, which are thrombogenic in nature and conducive to energy dissipation. Angulation-induced, shear stress-mediated shunt thrombosis is insensitive to aspirin therapy alone. Thus, for patients with central aortic shunts of longer length and with angulation, aspirin alone will provide insufficient protection against clotting. These patients are at risk for shunt thrombosis and significant morbidity and mortality, unless their anticoagulation regimen includes additional antiplatelet medications.

Failing left ventricle to ascending aorta conduit—Hybrid implantation of a melody valve and NuMed covered stent

We present the case of a 36-year-old woman with increasing shortness of breath, a new 3/4 diastolic murmur, and a complex history of LV outflow tract obstruction. She has undergone multiple surgeries including the replacement of her old LV apex to ascending aorta conduit with a 20-mm Gore-Tex tube graft, addition of a 24-mm homograft sutured between the conduit and the LV apex, and insertion of a 21-mm Freestyle porcine valve conduit between the Gore-Tex tube graft and allograft at age 23. The current assessment showed a failing Freestyle conduit prosthesis leading to left heart decompensation. Due to substantial surgical risk, the patient underwent successful implantation of a Melody valve into the Gore-Tex tube and exclusion of the failing Freestyle bioprosthesis with a NuMed CP stent in a hybrid procedure. The case nicely illustrates the collaborative potential of cardiovascular surgeons and interventional cardiologists in the new arena of a hybrid operating room. Complex hybrid procedures like the current one, especially those including percutaneous placements of valves, offer therapeutic options for patients that are otherwise too high risk for conventional open heart surgery.

Total Cavopulmonary Connection With Innovative Combined Lateral Tunnel and Extracardiac Conduit in Heterotaxy Syndrome

Total cavopulmonary connection remains a challenging procedure when treating heterotaxy syndrome patients with a widely separate drainage of the inferior vena cava and the hepatic vein into the common atrium. We trimmed a Gore-Tex tube graft (W.L. Gore & Associates, Flagstaff, AZ) to form a skirt to cover both openings of the inferior vena cava and the hepatic vein. This tubular structure pierces the atrium and travels outside the heart, and then reaches the inferior side of the pulmonary artery to avoid pulmonary vein obstruction. We then sutured the pierced atriotomy margin to the conduit. This innovative procedure has been shown to accommodate the widely separated hepatic vein drainage with a promising outcome.

Longitudinal growth of the autologous vessels above and below the Gore-Tex graft after the extracardiac conduit Fontan procedure☆

Reflecting excellent mid-term outcomes, extracardiac conduit Fontan procedure (ECFP) using Gore-Tex tube graft has been performed with increasing frequency in patients with functional single ventricle. Nevertheless, due to the lack of growth potential of the artificial conduit, the status of the venous pathway along with somatic growth is a continuing concern. In this study, we evaluated the longitudinal growth of the autologous vessels above and below the Gore-Tex graft used in the ECFP. This study included 34 patients who had completed cardiac catheterisations at 1 month and 5.1 years after the ECFP. The average age, weight and height at the ECFP were 3.8+/-2.5 years (1.8-12.7 years), 12.7+/-4.6 kg (7.4-33.0 kg) and 92.9+/-16.1cm (72.5-153.5 cm), respectively. We measured the vertical lengths of three different parts angiographically: the length between the confluence point of the innominate vein and the anastomotic site of the conduit to the pulmonary artery (SVC-C), the conduit vertical length (C) and the length between the confluence point of the hepatic vein and the conduit's anastomotic site to the inferior vena cava (IVC-C). We have not observed stenosis or thrombus formation in the conduit or distortion of the conduit or pulmonary artery in any of the cases. No intervention or re-operation related to the extracardiac conduit was required, and laminar flow through the conduit was maintained with efficient Fontan haemodynamics. At 5.1 years after the ECFP, the average weight and height gain were 10.3+/-4.4 kg and 28.5+/-1.9 cm, respectively. The length of SVC-C, C and IVC-C were significantly increased as 124+/-15%, 106+/-7% and 132+/-24%, respectively, compared to the lengths at 1 month after the ECFP. The degree of increase in SVC-C and IVC-C was significantly larger than that in C. Along with the patient's somatic growth, longitudinal growth of the autologous vessels above and below the Gore-Tex graft was demonstrated to compensate for the lack of growth potential of the artificial graft.

Combined Liver Resection and Reconstruction of the Supra-Renal Vena Cava

Liver tumors with inferior vena cava (IVC) involvement may require combined resection of the liver and IVC. This approach, with its high surgical risks and poor long-term prognosis, was precluded until the development of neoadjuvant chemotherapy, portal vein embolization, reinforced vascular prostheses, and technical advances in liver transplantation. We reviewed 22 cases of hepatectomy with retrohepatic IVC resection and reconstruction. The patients had a median age of 51.5 years (range, 32.8-75.3 years). Indications for resection were: liver metastases (n = 9), cholangiocarcinoma (n = 8), hepatocellular carcinoma (n = 2), other cancers (n = 3). The liver resections carried out included 18 first, 3 second, and one third hepatectomy. Segment 1 (caudate lobe) was included in the specimen in 19 cases (86%). Resection concerned 1 to 6 liver segments (median = 5.0). Vascular control was achieved by vascular exclusion of the liver preserving the caval flow (n = 1), standard vascular exclusion of the liver (n = 12), in situ cold perfusion of the liver (n = 9). Ex situ surgery was not necessary in any case. Venovenous bypass was used in 12 cases. The IVC was reconstructed with a ringed Gore-Tex tube graft (n = 10), primarily (n = 8), or by caval plasty (n = 4). A main hepatic vein was reimplanted in 6 cases: into the native IVC (n = 4) or into a Gore-Tex tube graft (n = 2). One patient died (4.5%) due to catheter infection, 7 days after in situ cold perfusion with replacement of the vena cava. Eight patients (36%) had no complications and 14 patients (64%) had 23 complications. In all but 1 case, the complications were transient and successfully controlled. The patients stayed in intensive care for 3.3 +/- 2.0 days and in the hospital for 17.7 +/- 7.8 days. All vascular reconstructions were patent at last follow-up. With median follow-up of 19 months, 10 patients died of tumor recurrence and eleven were alive with (n = 5) or without (n = 6) disease. Actuarial 1-, 3-, and 5-year survival rates were 81.8%, 38.3%, and 38.3%, respectively. IVC resection and reconstruction combined with liver resection can be safely performed in selected patients. The lack of alternative treatments and the spontaneous poor prognosis justify this approach, provided that surgery is carried out at a center specialized in both liver surgery and liver transplantation. The development of adjuvant chemotherapy regimens is required to improve the long-term results of this salvage surgery.

Combined resection of the liver and inferior vena cava for hepatic malignancy.

The objective of this paper is to review the results of combined resection of the liver and inferior vena cava for hepatic malignancy. The morbidity and mortality along with preliminary survival data are assessed in order to determine the utility of this aggressive approach to otherwise unresectable tumors. Involvement of the inferior vena cava has traditionally been considered a contraindication to resection for advanced tumors of the liver because the surgical risks are high and the long-term prognosis is poor. Progress in liver surgery allows resection in some cases. Twenty-two patients undergoing hepatic resection from 1997 to 2003, that also required resection and reconstruction of the inferior vena cava (IVC), were reviewed. The median age was 49 years (range 2 to 68 years). Resections were carried out for: hepatocellular carcinoma (n = 6), colorectal metastases (n = 6), cholangiocarcinoma (n = 5), gastrointestinal stromal tumor (n = 2), hepatoblastoma (n = 2), and squamous cell carcinoma in 1 patient. Liver resections performed included 13 right trisegmentectomies, 6 right lobectomies extended to include the caudate lobe, and 3 left trisegmentectomies. Complex ex vivo procedures were performed in 2 cases using venovenous bypass while the other 20 cases were performed using varying degrees of vascular isolation. In situ cold perfusion of the liver was used in 1 case. The IVC was reconstructed with ringed Gore-Tex tube graft (n = 14), primarily (n = 6), or with Gore-Tex patches (n = 2). There were 2 perioperative deaths (9%). One cirrhotic patient died of liver failure 3 weeks post operatively and 1 patient with cholangiocarcinoma died of pulmonary hemorrhage secondary to a cavitating pulmonary infection after aspiration pneumonia 6 weeks after resection. Six patients had evidence of postoperative liver failure that resolved with supportive management and 2 patients required temporary dialysis. All vascular reconstructions were patent at last follow-up. With median follow-up of 26 months, 5 patients have died of recurrent malignancy at 44, 40, 32, 26, and 24 months, while an additional patient is alive with disease at 31 months. Actuarial 1-, 3-, and 5-year survivals were 85%, 60%, and 33%, respectively. IVC involvement by hepatic malignancy does not necessarily preclude resection. Liver resection with reconstruction of the inferior vena cava can be performed in selected cases. The increased risk associated with the procedure appears to be balanced by the possible benefits, particularly when the lack of alternative curative approaches is considered.

Distribution of Sac Pressure in an Experimental Aneurysm Model After Endovascular Repair:The Effect of Endoleak Types I and II

Purpose To study in an experimental aneurysm model the differential distribution of strain/pressure (S/P) on the aneurysm wall before and after endograft exclusion and in the presence of individual type I and type II endoleaks. Methods Two tapered elliptical Gore-Tex patches were sutured to an anterior and posterior longitudinal arteriotomy of an 8-mm Gore-Tex tube graft, thus creating a fusiform aneurysm. Two S/P transducers were placed at the proximal sac adjacent to the proximal neck, 2 at the site of the widest sac diameter, and 2 at the sac adjacent to the distal neck. The aneurysm, which was connected to a pulsatile pump system, was excluded using a 10-mm endograft. Type I and type II endoleaks were created and tested individually. S/P measurements were obtained at systemic systolic pressures (BP) of 80, 110, and 150 mmHg. Thrombosis of the sac contents was induced by injection of thrombin and calcium in the sac. Angiography was used to verify presence or absence of flow in the sac. Results Aneurysm exclusion resulted in significant S/P reductions at all 3 BP levels versus prior to exclusion (p 0.05 for all 3 BP levels). In the presence of a proximal type I endoleak, S/P distribution was not uniform, and S/P at the proximal neck was close to S/P prior to exclusion (p>0.05 no graft versus type I endoleak for all 3 BP levels). This was also true in the presence of thrombus. With a type II endoleak, S/P was more evenly distributed and was not significantly elevated compared to the pressure without an endoleak (p>0.05, graft versus type II endoleak for all 3 BP levels). Thrombus had no effect on intrasac S/P with a type II endoleak. Intrasac S/P was significantly higher in the presence of a type I endoleak compared to a type II endoleak when BP=150 mmHg (p=0.008). Conclusions Endovascular exclusion of an aneurysm results in uniform S/P reduction in the aneurysm sac. Type I endoleak, but not type II endoleak, results in significantly higher S/P in an area of the sac adjacent to the proximal neck. Thrombus does not result in significantly different S/P distribution in the aneurysm sac.

Distribution of sac pressure in an experimental aneurysm model after endovascular repair: the effect of endoleak types I and II.

To study in an experimental aneurysm model the differential distribution of strain/pressure (S/P) on the aneurysm wall before and after endograft exclusion and in the presence of individual type I and type II endoleaks. Two tapered elliptical Gore-Tex patches were sutured to an anterior and posterior longitudinal arteriotomy of an 8-mm Gore-Tex tube graft, thus creating a fusiform aneurysm. Two S/P transducers were placed at the proximal sac adjacent to the proximal neck, 2 at the site of the widest sac diameter, and 2 at the sac adjacent to the distal neck. The aneurysm, which was connected to a pulsatile pump system, was excluded using a 10-mm endograft. Type I and type II endoleaks were created and tested individually. S/P measurements were obtained at systemic systolic pressures (BP) of 80, 110, and 150 mmHg. Thrombosis of the sac contents was induced by injection of thrombin and calcium in the sac. Angiography was used to verify presence or absence of flow in the sac. Aneurysm exclusion resulted in significant S/P reductions at all 3 BP levels versus prior to exclusion (p<0.05). Thrombus in the sac did not alter S/P in the excluded sac (p>0.05 for all 3 BP levels). In the presence of a proximal type I endoleak, S/P distribution was not uniform, and S/P at the proximal neck was close to S/P prior to exclusion (p>0.05 no graft versus type I endoleak for all 3 BP levels). This was also true in the presence of thrombus. With a type II endoleak, S/P was more evenly distributed and was not significantly elevated compared to the pressure without an endoleak (p>0.05, graft versus type II endoleak for all 3 BP levels). Thrombus had no effect on intrasac S/P with a type II endoleak. Intrasac S/P was significantly higher in the presence of a type I endoleak compared to a type II endoleak when BP=150 mmHg (p=0.008). Endovascular exclusion of an aneurysm results in uniform S/P reduction in the aneurysm sac. Type I endoleak, but not type II endoleak, results in significantly higher S/P in an area of the sac adjacent to the proximal neck. Thrombus does not result in significantly different S/P distribution in the aneurysm sac.

The results of microneurosurgery of the inferior alveolar and lingual nerve

Purpose: The goal was to evaluate the experience of one surgical unit during a 5-year period in the evaluation and management of patients with injuries of the inferior alveolar and lingual nerve with particular reference to indications for and results of microneurosurgery. Patients and methods: This study includes all patients referred with a diagnosis of injury to the inferior alveolar or lingual nerve during 5-year period from January 1, 1994, to January 1, 1999. All patients were evaluated with Frey's hairs for touch and direction sense, 2-point discrimination, and hot and cold water and Minnesota thermal discs for temperature sensation. Patients who fulfilled certain specified criteria were offered microneurosurgery, and the results were evaluated for those who underwent microneurosurgery. Results: The study consisted of 880 consecutive patients; 96 were thought to fulfill the criteria for microneurosurgery. Of these, 51 underwent microneurosurgical exploration and repair. In 5 patients, no injury could be detected at surgery, and no corrective surgery was performed other than decompression. In 26 patients, excision and direct anastomosis were performed, and in an additional 20 patients, nerve gap reconstruction was performed. In 16 of these 20 patients, reconstruction was performed with an autogenous vein graft, and in 2 patients, a Gore-Tex tube graft (W.L. Gore & Associates, Inc, Flagstaff, AZ) was used to bridge the nerve gap. In 2 patients, an autogenous nerve was used. Thirty-four of the repairs were made on the lingual nerve, and 17 were made on the inferior alveolar nerve. With the use of established criteria, 10 patients were considered to have had a good improvement in sensation, 18 patients were considered to have had some improvement in sensation, and 22 patients were considered to have had no improvement in sensation; 1 patient reported an increase in dysesthesia after surgery. The semiobjective assessment of patients did not always correspond with the patients' subjective evaluation. Conclusion: In a relatively small study in selected cases, microneurosurgery can provide a reasonable result in improving sensation in the inferior alveolar and lingual nerve. More than 50% of patients experienced some improvement in sensation, and dysesthesia did not develop after surgery in any patient who did not have it before surgery. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:485-489, 2002

Resection of the Inferior Vena Cava for Hepatic Malignancy

Involvement of the inferior vena cava (IVC) by hepatic tumors, although uncommon, is considered to be unresectable by standard surgical techniques. Recent advances in hepatic surgery have made combined hepatic and vena caval resection possible. The purpose of this study is to describe the surgical techniques and early results of combined resection of the liver and IVC. From 1997 to 2000, 11 patients underwent resection of the IVC along with four to seven liver segments. Resections were carried out for hepatocellular carcinoma (four); colorectal metastases (four); and hepatoblastoma, gastrointestinal stromal tumor metastases, and squamous cell carcinoma in one patient each. Ex vivo procedures were performed twice, and total vascular isolation was used in the nine other cases. The IVC was reconstructed with ringed Gore-Tex tube graft (five), primarily (five), or with Gore-Tex patches (one). There were two early deaths: one from liver failure at 3 weeks and one from sepsis secondary to a perforated segment of small bowel 4 months postresection. One patient with a gastrointestinal stromal tumor died at 32 months of recurrent tumor and one patient with hepatocellular carcinoma is alive with recurrent tumor at 16 months. The remaining patients are alive and disease free with follow-up ranging from 3 to 40 months without evidence of IVC occlusion. Combined resection of the liver and IVC is a formidable undertaking with substantial surgical risk. However, this aggressive surgical approach offers a chance for cure in patients with tumors involving the IVC that would otherwise have a dismal prognosis.

Ex vivo and in situ resection of inferior vena cava with hepatectomy for colorectal metastases.

To describe the surgical techniques and early results of inferior vena cava (IVC) resection in patients with advanced liver tumors. Involvement of the IVC by hepatic tumors, although rare, is considered inoperable by standard resection techniques. Concomitant hepatic and IVC resection is required to achieve adequate tumor clearance. Between February 1995 and February 1999, 158 patients underwent hepatic resection for colorectal metastases in the authors' unit. Eight patients, aged 42 to 80 years (mean 62 years), with hepatic metastases from colorectal cancer underwent concomitant resection of the IVC and four to six hepatic segments. Resections were carried out under total hepatic vascular exclusion in four patients and ex vivo in four patients. Between 30 degrees and 360 degrees of the retrohepatic IVC was resected and replaced with an autogenous vein patch (n = 1), a ringed Gore-Tex tube graft (n = 2), a Dacron tube graft (n = 1), or a patch (n = 3) or was repaired by primary suturing (n = 1). There were two early deaths from multiple organ failure. One patient survived 30 months after ex vivo resection but died of renal cell carcinoma, and another died with recurrent disease at 9 months. The remaining four patients remained alive 5 to 12 months after surgery, with no hepatic failure or venous obstruction; tumor recurrence was present in two. Nonthrombotic occlusion of the neocava occurred in one patient and was stented successfully. Although concomitant hepatic and IVC resection is associated with a considerable surgical risk, this aggressive surgical approach offers hope for patients with hepatic tumors involving the IVC, who would otherwise have a dismal prognosis. This procedure can be performed under total hepatic vascular exclusion, with or without venovenous bypass, and by ex vivo bench resection.

Reduced frequency of occlusion of aorto-pulmonary shunts in infants receiving aspirin.

Infants with severely reduced pulmonary perfusion due to complex congenital cardiac malformations are in need of an improved flow of blood to the lungs. One option for treatment is to construct a systemic-to-pulmonary arterial shunt. Although such shunts have been used since 1945, their spontaneous occlusion remains a major problem in the long-term. We studied all infants in whom a systemic-to-pulmonary arterial shunt had been constructed using a Gore-Tex tube graft between December 1989 and March 1996. Of 46 infants undergoing construction of a shunt, 7 (15%) died within 30 days of surgery. The shunts had to be taken down in 2 infants. Thus, 37 infants were included in the study. All but three infants received Aspirin. Aspirin was discontinued on the personal decision of individual physicians. Of 22 infants, 3 never received Aspirin, and in 19 it was stopped well before undertaking subsequent surgery. Aspirin was administered continuously to 15 infants until further surgery. Those in whom Aspirin was discontinued, or not given, and those receiving Aspirin until further surgery, were comparable concerning their age, time of follow-up, severity of the cardiac lesions, and size and type of shunt. Partial or complete occlusion of the shunt occurred in 2 of 15 (13%) infants taking Aspirin, but was seen in 12 of 22 (54%) infants in whom Aspirin was discontinued. Of these, 3 died due to acute occlusion of the shunt. Aspirin reduced effectively the rate of occlusion of systemic-to-pulmonary arterial shunts, and should be continued as long as the shunt is in place.

Failure of ureteral replacement with gore-tex tube grafts

Objectives. To evaluate the role of polytetrafluoroethylene (Gore-Tex) as a ureteral substitute in dogs after resection of a 5 to 8-cm-long middle segment. Methods. Five mongrel dogs underwent resection of the middle segment of the left ureter and segmental replacement of the resected part with segments of Gore-Tex over a double-J catheter. The double-J stents were removed at 21 days and the dogs were evaluated by excretory urography and abdominal ultrasonography 12 weeks after surgery. They were then killed and the ureters and the kidneys examined both grossly and microscopically. Results. There was radiologic evidence of advanced hydronephrosis on the left side in all 5 dogs. Grossly, the left kidneys showed marked pelvic and proximal ureteral dilatation and atrophy of parenchyma. Severe stricture at the anastomotic sites and marked fibrous tissue around the prostheses were found. No cellular lining was found in the Gore-Tex lumen. Conclusions. There is no potential for ureteral replacement by Gore-Tex tube graft.

Repair of multiple mycotic aortic aneurysms in a newborn

Thoracoabdominal aortic and common and internal iliac artery mycotic aneurysms resulted from an umbilical arterial catheter in a 3 1 2 - week-old boy. He underwent staged repair including an 8-mm Gore-tex tube graft, primary repair of the common iliac artery aneurysm, and resection of the internal iliac aneurysm. His operative and postoperative course was uneventful. He was asymptomatic at 17 months' follow-up, with equal blood pressure in the upper and lower extremities. Magnetic resonance imaging showed no stenoses or recurrent aneurysms at the anastomotic sites of the Gore-tex tube graft. Blood supply to his left leg came from collaterals, principally a large crossing vessel from the right iliac artery. This case represents the first successful aortic replacement in a 5 week old with extensive involvement of the thoracoabdominal aorta and its branch vessels.

Pulmonary vascular disease in shunted and nonshunted patients with tetralogy of fallot.

Histometric analysis of pulmonary vascular disease was performed in 13 shunted and 21 nonshunted patients with tetralogy of Fallot, and in 29 normal controls. There was no significant difference in the medial thickness of the small pulmonary arteries between cases of tetralogy of Fallot and normal controls, but the media in shunted cases of tetralogy of Fallot were thicker than in the nonshunted cases. Intimal fibrosis, regarded as organized thrombi, and thrombi of small pulmonary arteries were observed generally after 4 years of age in both the shunted and nonshunted cases of tetralogy of Fallot. Intimal proliferation of musculoelastosis which was formed of longitudinal smooth muscle bundles and elastic fibers was characteristic in shunted patients, especially after the central palliation procedure, Waterston anastomosis or modified Blalock-Taussig (BT) anastomosis using the Gore-Tex tube graft. However, it was not usually seen in the BT anastomosis cases. Unexpected pulmonary hypertension due to the shunt operation is thought to be the cause of musculoelastosis, because musculoelastosis was observed even in a patient with pulmonary hypertension only 3 weeks following surgery. We therefore recommend the original BT anastomosis as the shunt procedure. When considering the use of other shunt operations in which there is a possibility of placing a pressure load on the pulmonary vascular bed, attention must be given to the size of the anastomosis or artificial tube graft.