Synthetic Aortic Graft Research Articles

An experimental evaluation of a concept to improve conventional aortic prostheses

Conventionally used textile prosthesis for traditional open surgical repair (OSR) of aortic aneurysms have a lower compliance than the native aortic tissue. Graft placements lead to an acute drop in compliance which effects cardiovascular risk and the development of graft related complications. A custom-made spring casing was applied to a Dacron graft segment under physiological pressure conditions within a five-element biventricular mock circulation loop, to investigate experimentally a concept to improve the compliance of a conventional aortic prosthesis by changing the transverse graft cross-section. Two different prosthesis locations, proximal and distal of compliant silicone tubing were used to study uniaxial graft compression with an elastic device. To characterise the devices’ performance by means of pulse pressure (PP), diastolic pressure (Pdia) and pulse wave velocity(PWV), fluid pressures and flow were recorded.In a proximal graft setting (ascending aorta repair) elastic uniaxial compression with a custom-made spring casing (2 cm width) could significantly reduce PP by 10–14% (p < .001) and slowed PWV from 6.7 to 5.2 m/s (22%, p = .002). Applied to a graft in a distal position, the spring casing demonstrated less impact on PP (2–10%), but significantly reduced PWV in this mock aorta segment from 13.7 to 5.5 m/s (60%, p = .004). In conclusion, a newly conceptualised spring casing applied to the external wall of synthetic aortic grafts can reduce PP and slow PWV. By restoring elastic aortic recoil in stiff textile aortic prostheses, the presented concept is a potential solution to improve long-term aortic prosthesis related complications.

Two cases of aortoenteric fistula with gastrointestinal bleeding.

Aortoenteric fistula (AEF) is a life-threatening condition that can present with gastrointestinal (GI) bleeding. AEFs have been classified into primary and secondary types. Primary AEF (PAEF) is a direct communication between the aorta and the GI tract. Secondary AEF (SAEF) is the result of a previous abdominal aortic aneurysm repair involving placement of a synthetic aortic graft. Diagnosis of AEF, especially PAEF, is difficult largely because AEF is so rarely encountered in practice. Computed tomography (CT) and endoscopic gastroduodenoscopy (EGD) are most frequently used to diagnose AEF, with abdominal contrast-enhanced CT being the preferred initial diagnostic test of choice. Although EGD can exclude other common causes of GI hemorrhage, it cannot be used to rule out AEF when another source of bleeding is identified, as the two conditions can coexist. We discuss here two patients with GI bleeding who were diagnosed as PAEF and SAEF. We tried to diagnose and treat with EGD, but failed. That bleeding was due to an AEF became evident when abdominal CT scans revealed direct extravasation of contrast media from the abdominal aorta into the GI tract. The lack of awareness of AEF, coupled with the inaccessibility to the distal duodenum via EGD, were probably responsible for initial misdiagnosis and delay of appropriate management. We suggest that the diagnosis of AEF remains dependent on the clinician's heightened suspicion.

Aorto-duodenal fistula: a rare but serious complication of gastrointestinal hemorrhage. A case report.

A primary aortoduodenal fistula (PADF) is a rare cause of gastrointestinal bleeding that is difficult to diagnose (and sometimes not diagnosed until a laparotomy.) A PADF is associated with high mortality if undiagnosed and untreated (the mortality rate of nearly 100% in the absence of a surgical intervention). While this condition is extremely rare with an incidence rate at autopsy of 0.04% to 0.07%, a secondary ADF occurs much more commonly (the post-operative incidence of 0.5% to 2.3%) and is due to prior aortic surgery and/or the placement of a synthetic aortic graft. It should be considered in any elderly patient who presents with upper gastrointestinal bleeding in the context of a known abdominal aortic aneurysm or without it when no identifiable source of bleeding is found. We present an autopsy case of a 59-year-old man with no history of an abdominal aortic aneurysm who presented with intermittent massive gastrointestinal bleeding. The autopsy revealed a pinhole fistula. It was identified between an atherosclerotic abdominal aortic aneurysm and the lower horizontal part of the duodenum. Our case indicates that the aortoenteric fistula can result in fatal gastrointestinal bleeding. This case is unique in that the fistula formed as a result of a complex atherosclerotic abdominal aorta and a localized necrotizing granulomatous aortitis the etiology of which was not clear.

Matériaux de reconstruction aortique résistants à la contamination bactérienne

Synthetic graft infection is a rare but extremely serious complication of aortic reconstruction procedures, with morbidity-mortality rates as high as 60 %. Some of the proteins (albumin, gelatin, collagen) used to coat polyester graft materials can establish ionic bonds with antibiotics or can capture antiseptics such as triclosan or ionic silver in their matrices. These active substances are then released from the graft, at varying rates, during the coating degradation that takes place during the weeks following polyester graft implantation in living tissues. Rifampin-bonded prostheses have proved effective against S. aureus and S. epidermidis in several canine models of synthetic aortic graft infection. Rifampin-bonded grafts have also been used successfully in patients with synthetic aortic graft infection by low-virulence bacteria. However, their effectiveness may be limited by the diverse and changing ecology of synthetic aortic graft infections, with an increasing prevalence of multidrug-resistant bacteria and polymicrobial infections. These include species that are naturally, or are likely to become, resistant to rifampin. We evaluated silver-ion-bonded prostheses in this setting but observed a disappointingly high mid-term rate of recurrent infections. Over the past few years we have been involved in the development of polyester vascular prostheses functionalized with a hydroxypropyl-β-cyclodextrin polymeric matrix that can capture and elute several therapeutic agents. The results are promising, as these prostheses enable the sustained release of various antibiotics in amounts several times their minimum inhibitory concentrations. This provides a unique opportunity to functionalize materials for aortic graft reconstruction, based on epidemiological data or individual bacteriological findings.

High 18F-FDG Uptake in Synthetic Aortic Vascular Grafts on PET/CT in Symptomatic and Asymptomatic Patients

Graft infection is a serious complication to vascular surgery. The aim of this study was to assess (18)F-FDG uptake in vascular grafts in patients with or without symptoms of graft infection. In all 2,045 patients examined by PET/CT at our clinic, 16 patients with synthetic aortic grafts were identified and reevaluated for (18)F-FDG accumulation. Clinical and biochemical data were obtained from patient records. High (18)F-FDG uptake was found in 10 of 12 grafts in the patients who underwent open surgery and in 1 of 4 grafts in patients who underwent endovascular aneurysm repair. On the basis of biochemical and clinical data, it was concluded that 1 of the 16 patients had a graft infection at the time of investigation. (18)F-FDG uptake in vascular grafts was found in the vast majority of patients without graft infection. The risk of a false-positive diagnosis of graft infection by (18)F-FDG PET/CT is evident.

Intraaortic balloon pump counterpulsation after implantation of infrarenal and thoracoabdominal aortic protheses

Highly complex vascular surgery interventions have nowadays become possible due to sophisticated operative techniques and modern intra- and postoperative anesthesiological strategies. Accordingly, the number of high risk vascular surgery interventions rises continuously and thus, the number of secondary complications after high risk interventions increases as well and requires likewise extraordinary treatment concepts. We report of a 68-year old patient who 6 months previously was operated on a ruptured abdominal aneurysm, before he was admitted to our institution for the treatment of a type IIIb (Crawford classification) thoracoabdominal aneurysm. Intraoperatively we implanted a 26 mm Dacron prosthesis which was anastomosed with the previously existing infrarenal graft. Postoperatively the patient suffered from a hemodynamically significant myocardial infarction and acute coronary catheter intervention was necessary. However, circulatory stability could not be reestablished by interventional measures and we therefore decided to implant the intraaortic balloon pump despite the presence of two synthetic aortic grafts. However, the chance of success of such a manoeuver as well as the effectiveness of intraprosthetic counterpulsation was unclear and our literature research undertaken to predict the risk of such a manouver was unsatisfactory. We therefore want to report this case and compile the literature dealing with perceptions and complications of intraaortic counterpulsation after the implantation of synthetic aortic prostheses, since such a treatment option comes to an increased clinical application in comparable constellations.

Endovascular Repair of Multiple Peripheral Aneurysms via a Dual Approach Involving a Venous Graft Conduit

Introduction stent across the other sheath, thereby facilitating haemostasis on removal. The profunda femoris origin was The authors report the management of a difficult occluded with Gianturco embolisation coils (Cook U.K. Ltd.) following a satisfactory trial balloon occlusion. surgical problem involving the repair of multiple peripheral aneurysms in a patient with a pre-existing The CFA puncture site was used to sequentially deploy three Wallgraft endoprostheses (nominal size 9 mm synthetic aortic graft in whom autologous long saphenous vein was unavailable. This was carried out long, Boston Scientific Ltd.) within the SFA and venous graft, to exclude the aneurysmal SFA from the cirby an endovascular route through dual access sites, involving uniquely a venous graft conduit. culation. The distal vein graft puncture site was then used to deploy a further Wallgraft (9 mm×70 mm) within the aneurysmal external iliac and CFA. Balloon remodelling at the Wallgraft junctions reduced any Technical Report minor endoleaks. There were no immediate complications and the patient’s feet remained well perfused A 72-year-old man with a history of a coronary artery throughout the procedure. Follow-up arterial duplex bypass graft had previously undergone several surultrasound scans at 3 days, 2 months and 3 months gical procedures for aneurysmal disease including an demonstrated graft patency with aneurysmal exaortic reconstruction with a Dacron aorto-bi-iliac graft, clusion. The patient was discharged home 3 days a right-sided superficial femoral artery (SFA) to belowfollowing the procedure. The cost of four Wallgrafts knee popliteal long saphenous vein bypass graft, and was £3800. a left-sided SFA to peroneal long saphenous vein bypass graft. Since these procedures, however, he presented with multiple aneurysms (1.6–3.6 cm diaDiscussion meter) extending from the left external iliac to the femorodistal graft (Figure 1). The option of extensive surgical repair via a groin The patient underwent endovascular repair of the approach entailing a high risk of morbidity was unaneurysms under local anaesthetic (Figure 2). An antedesirable in this patient. Factors including in-situ syngrade left common femoral artery (CFA) puncture and thetic graft infection and perioperative haemorrhage retrograde distal saphenous vein graft puncture were were also major concerns. Furthermore, the reperformed and accessed with 10 French sheaths. Dual constructed aortic segment and the unavailability of sites were accessed to enable each to deploy a covered both long saphenous veins would clearly complicate a surgical challenge. The use of endovascular covered stents to repair ∗ Please address all correspondence to: R. D. Sayers, Consultant peripheral aneurysms is a relatively new modality. Vascular Surgeon, Department of Surgery, Leicester General Hospital, Gwendolen Road, Leicester LE5 4PW, U.K. Reports have been limited to only small numbers

Diagnosing sternal wound infections with 99mTc-labeled monoclonal granulocyte antibody scintigraphy

Postoperative mediastinitis is a serious complication of thoracic operations. The diagnosis can sometimes be difficult, especially in cases with subacute clinical presentation. The aim of this study was to assess the clinical use of granulocyte scintigraphy and tomography in the diagnosis of postoperative wound infection and mediastinitis. Twenty-nine patients after cardiothoracic operations were included, of whom 5 patients with a normal postoperative course formed the control group. We injected technetium 99m-monoclonal antigranulocyte antibodies and performed single-photon emission computed tomography after 4 and 20 hours. Twenty-three patients had both the early and the later scan; the remaining 6 had only the early scan. Seven scans indicated infection: 3 cases of mediastinitis, 2 cases of superficial wound infection, 1 case of infection in a synthetic aortic graft, and 1 case of osteitis. All were verified by bacterial culture. There was one false-negative scan; this patient had only the early registration and then was explored. This method when combined with the tomographic scan option is able to distinguish between deep and superficial infections. Two registrations must be made for optimal results.

Major Vascular Injury Secondary to Laparoscopy

Laparoscopic procedures are now performed by almost all surgeons. Major vascular injuries secondary to laparoscopy, which were anecdotal before 1990, are now seen more often. This article focuses on the authors' experience with arterial trauma related to laparoscopic procedures. Their hospital is a regional center with a population base of 350,000 and six peripheral hospitals. Between August 1994 and March 1996, 6 patients inadvertently sustained major vascular injuries in the course of laparoscopic surgery. These incidents were shared by 5 different surgeons in four different hospitals. Three patients sustained intestinal perforation and aortic transection during laparoscopic cholecystectomy, two related to insertion of the veress needle and one to insertion of a trocar. Two of these injuries were repaired by end-to-end anastomosis, while the third one required a synthetic aortic graft. A fourth patient sustained an aortic perforation during laparoscopic tubal ligation. The fifth and sixth patients had an iliac artery perforation-one during laparoscopic appendectomy and the other during abdominal hysterectomy. Blood lost in these patients varied between 3 and 26 liters, and the length of hospital stay varied from six days to three months. No deaths were reported. Major vascular injuries may arise during laparoscopic procedures. The authors' experience suggests these incidents are underreported. By understanding the way they occur, they believe these injuries are preventable.

Abdominal Aortic Aneurysmorrhaphy Combined with Biliary or Gastrointestinal Surgery

Abdominal aortic aneurysms occur in 2 to 5 per cent of the population over 60 years of age. Statistically, 7 per cent of patients with aneurysms will have associated cholelithiasis. The incidence of other concomitant intra-abdominal disease is much less. Because of the catastrophic complications associated with infection of synthetic aortic grafts, most authors have advised against opening a hollow viscus during aneurysm resection. Although Staphylococcus is the predominant organism responsible for graft infections, Szilagyi and associates and Liekweg and Greenfield found gram-negative organisms in 40 per cent of infected aortic prostheses. Thomas, Bickerstaff, and Fry and their coauthors have recommended caution when considering aneurysm resection and concomitant nonvascular operations. On the other hand, there is suggestive evidence that the risk of aneurysm rupture is increased in the postoperative period, especially if the aneurysm is greater than 6 cm in diameter. Therefore, optimum management of patients with aneurysms and other intra-abdominal pathology must reduce both the risk of graft infection and the risk of postoperative rupture. To reduce morbidity and mortality rates, careful preoperative evaluation for the detection and management of coexistent disease, the proper choice of intraoperative procedures, and close postoperative monitoring with prompt surgical intervention, as indicated, are essential.

Small bowel erosion by synthetic aortic grafts

Small bowel erosion by synthetic aortic grafts

Multiple Coarctations Of The Aorta

Multiple coarctations of the aorta are quite rare. In 1959, Zaroff and co-workers 1 reported a case with four separate coarctations of the aorta. Although they were able to find seven additional cases of multiple coarctation of the aorta in the literature, none of these had more than two areas of stenosis. In the case here reported there were four separate areas of narrowing, three in the aorta and one in the left subclavian artery. Although at first it was considered inoperable, successful operative repair was carried out at a later time with the use of a synthetic aortic graft and with a heartlung machine in the operating room for temporary aortic bypass if needed. Report of a Case A 5½-year-old boy was first seen in the Pediatric Clinic of the New York Hospital—Cornell Medical Center in 1952. A heart murmur had been heard when he was 2 weeks old,

Successful long synthetic aortic grafts with transmission of normal pulsation.

Successful long synthetic aortic grafts with transmission of normal pulsation.