The chemically treated bovine ureter--clinical performance of a novel biological vascular prosthesis.

AIM: This paper describes the rationale, development and clinical performance of a novel small-diameter vascular prosthesis of non-vascular animal tissue origin. METHOD: Durable conduits suitable for coronary and peripheral arterial reconstruction are prepared for the first time from non-vascular animal tissue. Australian bovine ureters from young steers from protected herds are processed to form strong, bloodflow-compatible and non-immunogenic biologic grafts ('Flonova', Bionova International Pty Ltd, Melbourne). Fifty-six patients lacking suitable autogenous veins received 62 prostheses (32 bypasses were implanted above knee and 30 below knee). Determination of patency and function included Doppler ultrasound, duplex scanning and angiography. FINDINGS: The primary patency rate at 1, 2 and 5 years, respectively was 67, 59 and 52% and the secondary patency for the same time frames was 88, 73 and 61%. There were no occlusions as a result of intimal hyperplasia. Dilatation of the wall was diagnosed in one prosthesis at 3.5 years, and one at 7 years, and a false aneurysm of unknown aetiology occurred in another at 3 months. There were no primary graft infections. CONCLUSION: This evaluation shows the chemically treated bovine ureter (CTBU) is a viable medium-term alternative to the currently available artificial vascular prostheses for peripheral revascularisation.

Tandem lesions of the carotid circulation: combined extracranial endarterectomy and intracranial transluminal angioplasty.

A case series is presented demonstrating a unique approach to the treatment of tandem atherosclerotic lesions of the internal carotid artery. Between 1994 and 1999 eight patients with tandem lesions of the internal carotid artery were treated by combined carotid endarterectomy for the proximal lesion and intraoperative angioplasty of the distal intracranial lesion via the carotid arteriotomy. The success and complication rates were evaluated. A 100% technical success rate was achieved with one post procedural complication by ipsilateral stroke within 24 h. The advantages of this technique include the treatment of tandem lesions by the one procedure, improved transluminal access to the intracranial lesion and the ability to reduce the risk of embolism by flow control during balloon inflation.

Adherence of human saphenous vein endothelial cell monolayers to tissue-engineered biomatrix vascular conduits.

This study investigates the adherence and retention under in vitro flow conditions of endothelium grown on the luminal surface of 4-mm-internal-diameter, biomatrix vascular conduits. The biomatrix vascular conduits are produced in living animals and consist of a naturally formed extracellular matrix wall incorporating a polyester mesh. We propose that the microarchitecture of the luminal surface may be conducive to endothelial cell (EC) seeding and to the formation of a firmly adherent endothelium without prior treatment of the surface with cell adhesives. ECs were isolated from segments of human saphenous vein and grown to confluence in a culture. Cultured cells were characterized by morphology and immunocytochemistry with anti-CD31, Von Willebrand factor, smooth muscle actin, cytokeratin, and the lectin Ulex Europaeus agglutinin. After culture, ECs were seeded (1 x 10(6) cell/mL) by rotation onto the luminal surface of 20-cm-long, biomatrix vascular conduits (n = 3). The seeded conduits were incubated for 72 h, and at set time points postseeding (1, 24, 48, and 72 h), the morphology, percentage luminal surface cover, and cell density (cell/cm(2)) were determined from en face preparations and histological cross sections. After 72 h in culture, the seeded conduits were subjected to a nonpulsatile flow for 1 h with culture media. A flow rate of 480 mL/min generated physiological-range shear stresses of 12 dyn/cm(2) on the endothelialized surface. After the flow, the conduits were fixed for histology, and the EC morphology and percentage luminal surface cover were determined. Quantification of the extent of luminal surface endothelialization, preflow and postflow, and cell densities at confluence was performed with digital imaging light microscopy and image analysis software. An analysis of the results demonstrated that confluent EC monolayers may be established on the luminal surface of biomatrix vascular conduits within 48 h. The formed endothelium was firmly adherent and was retained under physiological-range flow.

Treatment of renovascular disease with percutaneous stent insertion: long-term outcomes.

Renal artery stenosis is a common, progressive cause of hypertension and renal impairment, and is frequently treated with percutaneous transluminal dilatation and stenting. The outcome of this procedure is still being evaluated. The records of 198 consecutive patients who had stents inserted at the Royal Melbourne Hospital were analysed retrospectively, and adequate follow-up information on 148 (75%), in whom a total of 182 renal arteries had been treated was obtained. Technical success was achieved in 144 patients (97%). Complications occurred in 19 patients (13.3%), with major complications occurring in 10 (7.0%) and one death occurring in relation to the procedure. A fall in average systolic blood pressure of 13.2 mmHg (12.1-14.3 mmHg) was seen and a fall in diastolic blood pressure of 10.1 mmHg (9.3-10.9 mmHg), without an increase in the number of antihypertensive drugs used. Renal function remained stable in the majority of patients, particularly those who had minimal baseline renal impairment. Restenosis was common after 6 months, occurring eventually in 29% of screened patients, but was not shown to affect clinical outcomes. Insertion of renal artery stents is a safe and effective treatment for renal artery stenosis.

Mycotic cervical carotid aneurysm.

Mycotic aneurysms of the extracranial carotid arteries are rare, with only 27 cases reported in the English literature. The causative organism is most frequently Staphylococcus but infections due to Streptococcus, Salmonella and Klebsiella have been reported. Escherichia coli has been reported as the causative organism in three cases. Mycotic aneurysms usually present in the setting of generalized sepsis such as postoperative infection, septicaemia, dental sepsis, drug addiction or bacterial endocarditis. We report a patient who presented with a mycotic aneurysm of the internal carotid artery 2 months after undergoing a laparotomy for perineal sepsis.

The role of physical and chemical characteristics in assessing the performance of a new biological vascular graft.

Information obtained from physical and chemical characterization of vascular grafts can prove valuable in obtaining a preliminary assessment of potential in vivo performance. The data presented illustrate the concept and show that the new biological graft made from bovine ureters has adequate performance characteristics for use as a potentially successful vascular graft.

Combined carotid and coronary surgery.

A retrospective review of 40 consecutive patients undergoing combined coronary artery bypass grafting (CABG) and unilateral carotid endarterectomy (CEA) was carried out to determine the stroke rate for the procedure. Patients presenting with severe coronary artery disease judged to be at risk of imminent myocardial infarction, who had signs of cerebral ischaemia (70%) or asymptomatic carotid bruits (30%), were investigated for extracranial carotid vascular disease. Patients with severe stenotic carotid lesions associated with high risk coronary artery disease underwent combined CEA/CABG. Three patients had a previous contralateral CEA. The average age of the patients was 62 years, and there were 31 males and nine females. CEA was completed prior to CABG under the same general anaesthetic. There were 24 CEAs on the left and 16 on the right. Six patients suffered a postoperative cerebral ischaemic event (15.4%): a reversible ischaemic neurological deficit in three (7.7%), a transient ischaemic cerebral event in two (5.1%), and a permanent stroke occurred in one (2.6%). Two deaths occurred and both were cardiac related. Combined CEA/CABG in patients with stenotic lesions of the coronary and extra-cranial carotid vascular systems who are at risk of cerebral or myocardial infarction, can be performed with a permanent stroke rate within the published range for either CEA or CABG alone and with a mortality of 5%.

Balloon dilatation in the treatment of early intermittent claudication.

Balloon dilation of atherosclerotic arteries is an established procedure with a high success rate and low morbidity. In the past 18 months, 71 patients underwent balloon dilatation at the Royal Melbourne Hospital, with a success rate of 90%. This technique is most successful in short stenoses or occlusions, and earlier investigation of selected patients with intermittent claudication is recommended.

A new replacement for small vessels.

A new modification of the mandril-grown vascular prosthesis appears to combine the best features of presently available synthetic vascular replacement materials. Glutaraldehyde-tanned polyester mesh-supported conduits (diameters 4, 6, and 8 mm) grown in the subcutaneous tissue of sheep, maintain 100% patency in the aortic, aortoiliac, and common iliac positions of canine recipients for over 2 years. One-millimeter diameter grafts placed in the infrarenal abdominal aorta of rat recipients were patent in 72% for 6-month follow-up periods. The grafts maintained a modicum of antigenicity despite tanning, as evidenced by the slightly elevated hemagglutination (0 to 2 dilutions) titers against sheep red blood cells in ovine graft recipients and the accelerated rejection of the donor strain skin grafts in Fischer rats receiving Brown-Norway conduits. Finally, in a limited clinical study, 21 of 24 femoropopliteal and three of three femoroposterior tibial grafts remained patent in short follow-up periods (2 to 16 months). Two aortocoronary bypass grafts have continued to function in one patient for 19 months. Minimal inflammatory reaction and no aneurysmal degeneration were found in the material studied.

A vascular surgeon's approach to renal transplantation.

The blood vessels and blood supply are of first importance in organ transplantation, and the use of established vascular surgical principles and techniques can simplify renal grafting and reduce its risks and complications. This paper describes a vascular surgeon's approach to the problems of donor nephrectomy, kidney insertion, and the avoidance and management of complications, based on the surgical experience in the Royal Melbourne Hospital of some 350 transplants.

Embolization of traumatic aneurysm of the maxillary artery.

An expanding false aneurysm in the infratemporal fossa followed this patient's complicated jaw fracture. Successful Gelfoam embolization of the maxillary artery has controlled haemorrhage, treated the aneurysm, and avoided the hazards of local operative intervention. The technique of embolization has a place in the management of various difficult vascular problems.