The practice of carotid endarterectomy in Australasia.

BACKGROUND: Carotid endarterectomy (CEA) is a frequently performed surgical procedure and there are variations in the preoperative, operative and postoperative management related to this operation. METHODS: Questionnaires were sent to all 191 members of the Division of Vascular Surgery, Royal Australasian College of Surgeons, and the Australasian Chapter of the International Society of Cardiovascular Surgery. RESULTS: The questionnaire was returned by 179 surgeons (94%). One hundred and fifty-nine were vascular surgeons, of whom 139 perform CEA. Most surgeons reported performing more CEA than 5 years previously. Surgery for asymptomatic carotid stenosis was performed by 78% of surgeons at the time of the survey. Routine carotid angiography is performed pre-operatively for symptomatic patients by 61% of surgeons and for asymptomatic patients by 56%. Intra-operative shunting is used routinely by 37% of surgeons, selectively by 58% and never by 5%. Arteriotomy patch closure is performed routinely by 16%, usually by 30%, rarely by 52% and never by 3%. The favoured patch material is Dacron 39%, PTFE 19%, ankle long saphenous vein (LSV) 22%, thigh LSV 18% or other materials 2%. Compared to their practice 5 years previously, arterial patch closure is used more often by 42% of surgeons, the same by 51% and less by 7%. Postoperatively, patients are nursed mainly in intensive care (34%) or a high-dependency unit (33%). CONCLUSIONS: The practice of CEA by Australasian vascular surgeons reflects the recent trends reported in the world literature. Most Australasian surgeons perform CEA for asymptomatic disease. Forty per cent are performing CEA on the basis of duplex scanning alone. There is a trend towards increased use of patch closure. Most patients are managed in intensive care or high-dependency units.

New device for visual neodymium:YAG laser prostate ablation: acute and chronic canine evaluation.

This canine study (n = 6) evaluated the acute and chronic effects of Nd:YAG laser prostatectomy using a Prolase II fiber. The Prolase II device consists of a 1,000 microns quartz fiber which directs a cone of Nd:YAG laser energy, at 45 degrees to the axis of the fiber, into the prostatic urethra under direct visual guidance [visual laser ablation of prostate, (VLAP)]. Under visual guidance and saline irrigation, 60 seconds of 60 watts of laser power was delivered at 3, 6, 9, and 12 o'clock positions (14,400 J). One canine was instrumented but received no laser energy (control). One prostate was harvested acutely. The remaining four laser-treated dogs were evaluated at 6 to 16 weeks. The histopathology of acute laser effects shows areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 12.6 mm into the prostate. Two of the four dogs developed urinary retention at 6.5 and 9 weeks. On examination, both were found to have fibrotic strictures at the distal prostatic urethra with markedly dilated proximal prostatic urethral lumens (1.98 and 2.8 cm). Two other dogs showed no signs of urinary retention at sacrifice. Histopathology, both the 6 and 16 week laser-treated animals without urinary retention demonstrated dilated prostatic urethras with maximum cross-sectional diameters of 1.52 and 1.50 cm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Nd:YAG laser-welded canine arteriovenous anastomoses.

This preliminary report describes formation of femoral arterio-venous fistulas (n = 10) in six dogs using a 1.32-microns wavelength Nd:YAG laser welding technique. Stay sutures (6-0 polypropylene) were placed at 5-7 mm intervals along the anastomoses for vessel apposition. Delivery of laser energy through a 400-microns diameter fiber optic was controlled by a new computer-based software system. At 3 mm distance above the anastomosis, energy fluences of 110-260 J/mm2/cm length of anastomosis were used for laser welding. One or two additional hemostatic sutures were required in seven of the ten anastomoses. Flow was maintained for 1-2 hours prior to tissue harvesting. No thrombosis or delayed anastomotic failures were observed after initial welding and repair. Histologic examination revealed good apposition and adherence between wall layers and a fibrinous coagulum at the intimal junctions. Mild thermal injury of the wall was present at some anastomoses. This early investigation suggests that a 1.32 microns Nd:YAG laser welding technique can successfully create large vessel arteriovenous fistulas in the canine.

Intravascular ultrasound imaging: an essential component of angioplasty assessment and vascular stent deployment.

Potential early complications of balloon angioplasty include occlusion due to vessel wall recoil, medial dissection, creation of intimal flaps, spasm and luminal thrombosis. These features have also been implicated in the development of restenosis and late occlusion. As a possible solution to these problems, an endovascular scaffold (stent) was proposed by Dotter in the 1960s, and initial studies suggested that use of such a device in specific circumstances may reduce complications related to major dissection, vessel recoil and spams. This paper reports the utility of two- and three-dimensional intravascular ultrasound (IVUS) imaging in assessing arterial morphology following balloon angioplasty, and guiding the need for, and adequacy of deployment of intravascular stents. IVUS imaging provides a technique to accurately assess the immediate results of angioplasty and examine both the luminal size and contour following intervention. Accurate imaging such as this is essential for the successful use of balloon expandable stents, by ensuring correct initial positioning and complete deployment at the time of balloon expansion. Two cases are reported which highlight the important issues which are critical to the ongoing development of endovascular therapies: (i) accurate assessment of the angioplasty results, and (ii) selection and confirmation of stent deployment. We conclude that IVUS imaging may provide a new standard for the assessment of angioplasty procedures and will play a pivotal role in identifying failure mechanisms of endovascular interventions.

Intravascular ultrasound imaging: development and clinical applications.

Intravascular ultrasound is an exciting, new catheter based technique for imaging blood vessels. It provides accurate, real-time information about the types and distribution of vascular disease and displays both the macro- and micro-structure of blood vessels utilizating transducer frequencies of 10 MHz to 50 MHz. This paper discusses the development and current clinical applications of intravascular ultrasound technology, based on early intracardiac devices in the 1950s and resulting in very small diameter (1.3 mm), flexible probes in the 1990s for use in coronary and small peripheral vessels. Preliminary studies have established the dimensional accuracy of intravascular ultrasound, and more recent techniques such as three-dimensional image reconstruction have produced a very powerful research and clinical tool. The value of intravascular ultrasound in the diagnosis and therapy of vascular disease is based on its ability to define the transmural distribution of disease within the vessel, characterize plaque and intimal lesions, and provide accurate cross-sectional information regarding luminal and vessel wall morphology before and after intervention. Major priorities in the ongoing development of intravascular ultrasound are the need for further miniaturization and cost-effective manufacturing. Future angioplasty guidance devices may combine the benefits of angioscopy and intravascular ultrasound in a single delivery system suitable for incorporation into any ablative (mechanical or laser) catheter.

Computerized surgical databases: introduction to design and function.

There has been an enormous increase in the variety and volume of information encountered in surgical practice, either as measurable clinical variables or laboratory research data over the last three decades. Despite its form and origin, this information remains the basis of both daily clinical decision making and analytical research. Inferences drawn from past experience will modify an individual's approach to disease and treatment. However, when the demands of information processing cannot be met, mischief begins and quality of care declines. Modern computers offer an extraordinarily powerful method of processing the large volumes of medical data that are acquired, and provide techniques for analysis that would have been impossible, and often inconceivable, without computers. The applications of computer technology to surgical data management range from such simple and repetitive tasks as practice administration and accounting to elegant statistical and image analysis. This paper outlines the utility of computerized data management in clinical surgery and surgical research, and describes techniques for designing and implementing a customized surgical database system.

Endoscopic surgery training: application of an in vitro trainer and in vivo swine model.

The development of endoscopic surgical procedures is changing general surgery, with many operations such as cholecystectomy, appendectomy, and hernia repair being performed using laparoscopic surgical techniques. Training and credentialing of surgeons are key issues for the safe and ethical introduction of these new procedures. This article reviews techniques employed at our institution for laparoscopic surgical training and certification including didactic instruction, an in-vitro model for learning instrumentation and hand-eye coordination, and in-vivo training using the porcine animal model.

Pathology of arterial disease: influence of morphology and distribution of lesions on interventional therapy.

The pathologic morphology and distribution of arterial diseases determine the adaptability and utility of interventional therapies. This paper focuses on the aspects of lesion pathology which impact on the choice of surgical and endovascular approaches, and outlines the efficacy and limitations of the methods determined by these factors. An extensive review of vascular disease processes is beyond the scope of the paper, so individual entities will only be discussed in the context of pathologic factors affecting interventional approaches. Selected references are included to guide the interested reader to more extensive reviews.

Imaging technologies in cardiovascular interventions.

New and exciting vascular imaging technologies are assuming increasingly important roles in the management of vascular disease. Non-invasive modalities such as computerized tomography, magnetic resonance imaging and duplex ultrasound supplement the information obtained by invasive techniques including angiography, angioscopy and intraluminal ultrasound. This paper outlines the modern and developing vascular imaging techniques that are rapidly becoming integral components of therapeutic devices as well as advanced diagnostic systems.

Argon laser-welded bovine heterograft anastomoses.

UNLABELLED: This study evaluated the strength of laser-welded arteriovenous shunts established using St. Jude BioPolyMeric vascular grafts. The arterial anastomoses of the biological graft were laser welded with and without the addition of soluble collagen or fibrin sealant. In four dogs, 16 arteriovenous grafts were implanted between the femoral artery and vein or the carotid artery and jugular vein using a 6 cm long, 4 mm internal diameter prosthesis. The 16 arterial anastomoses were evenly divided into four groups: sutured control, laser welded (LW), LW with soluble collagen applied immediately before and during welding, and LW with fibrin sealant applied after welding. All arterial control and venous anastomoses were sutured using continuous 6-0 polypropylene suture. All LW anastomoses were initially divided into six 5 mm long segments using six evenly spaced 6-0 polypropylene stay sutures. Each segment was laser welded using 15 to 18 5-sec pulses of the 0.5 W (7.5 W/cm 2) argon laser energy delivered via a 300 mum fiber while cooling the tissue with slow-drip saline irrigation. Blood flow was established and maintained through each anastomosis for 1 h. The vessels were then controlled, and anastomotic bursting pressure was determined with infusion of heparinized blood. RESULTS: An additional hemostatic suture was required in 3 LW anastomoses (2 LW, 1 LW with collagen). Mean bursting pressures (mm Hg) of the arterial anastomoses were as follows: sutured controls 165 +/- 159, LW 144 +/- 58, LW and collagen 93 +/- 47, LW and fibrin sealant 181 +/- 45.(ABSTRACT TRUNCATED AT 250 WORDS)

Three-dimensional intravascular ultrasound imaging of normal and diseased canine and human arteries.

This study reports three-dimensional reconstruction of two-dimensional intravascular ultrasound images obtained along 5 cm vessel segments. Each three-dimensional image was produced by computerized "stacking" of a set of consecutive two-dimensional images (mode 90 images per set; range 32 to 256). Three-dimensional images (n = 26) were obtained from 11 human normal and atherosclerotic arteries (three in vitro and eight in vivo) and five in vivo canine studies. In vivo human examinations included three iliac, one deep, and three superficial femoral arteries and one aortic dissection. Five in vivo canine vessels (three iliac stenoses and two aortic dissections) were imaged before and after intraluminal stent deployment. Images were displayed on a gray-scale monitor, allowing examination of vessel images as complete cylinders or longitudinal hemisections in any user-defined plane. This enabled global examination of vascular segments and identified luminal shape, wall thickness, and distribution and morphology of plaques. Reconstructions of aortic dissections illustrated the extent of the dissection and produced an anatomic picture of the false lumen. Three-dimensional imaging enhanced stent deployment by identifying the site for deployment, dimensions of the vessel lumen, and changes in morphology after stent insertion. There was good correlation in vessel dimensions measured by angiography, two-dimensional intravascular ultrasonography and longitudinal gray-scale reconstructions (r = 0.74 to 0.95; p = 0.34 to 0.001) but poor correlation with measurements from three-dimensional surface-rendered images (r = 0.13 to 0.48; p = 0.42 to 0.87). We conclude that three-dimensional intravascular ultrasound imaging is an innovative new method for identifying the type, extent, and spatial configuration of arterial disease, with promising diagnostic and therapeutic applications.

Three-dimensional transrectal ultrasound: preliminary patient evaluation.

Transrectal ultrasound is uniquely useful in diagnosing and localizing the extent of lower colon and rectal disease. This paper reports the preliminary evaluation of three-dimensional intraluminal ultrasound imaging of normal and diseased rectal segments. The three-dimensional reconstructions were produced using a computerized PC based image analysis system which aligns ultrasound images to produce the three-dimensional images. A unique perspective for displaying both normal and pathologic anatomy is achieved using this new technology and the method has promising diagnostic and therapeutic potentials.

Intravascular ultrasound imaging: the new standard for guidance and assessment of endovascular interventions?

Intravascular ultrasound has developed rapidly during the last few years, and provides a unique perspective from which to view vascular disease and the effects of intervention. This catheter-based imaging technique utilizes advances in echographic data processing and computerized image manipulation to produce accurate luminal and transmural images of blood vessels. Although these devices have only been available for a relatively short time, numerous diagnostic and therapeutic applications have been reported. By providing a detailed image of vessels before, during, and after intervention, intravascular ultrasound provides a method for both guidance of endoluminal devices and immediate assessment of the results of therapeutic techniques including balloon angioplasty, atherectomy, laser-assisted angioplasty, and intravascular stent deployment. Intravascular ultrasound also offers exciting possibilities in peripheral vascular research such as investigation of blood vessel compliance, dynamic changes in the vessel wall caused by disease or pharmacologic intervention, and elucidation of the morphologic changes associated with the natural history of atherosclerosis.

Intravascular ultrasonography.

Intravascular ultrasonography is developing rapidly as a method for defining the transmural anatomy of vascular structures, with diagnostic and therapeutic applications. The ultrasound technology not only has unique diagnostic capabilities by defining the distribution and character of lesions, but also provides accurate control information regarding efficacy of angioplasty methods. An exciting recent development is the three-dimensional reconstruction of two-dimensional images which permits global examination of luminal and transmural vessel morphology. This technology may enable improved guidance of intraluminal devices to enhance lesion removal without damaging adjacent normal wall structure and appropriate device selection by differentiating specific plaque characteristics.

Sequential intraluminal ultrasound evaluation of balloon angioplasty of an iliac artery lesion.

This report describes intravascular ultrasound imaging of a localized 81% stenosis in the left common iliac artery of a 52-year-old woman. The lesion was dilated using an 8 mm balloon and was imaged pre- and post-dilation using arteriography and a 5F, 30 Mhz intravascular ultrasound catheter. The same site was imaged again intraoperatively at two months following the initial procedure using an 8F, 20 Mhz intravascular ultrasound catheter when the patient had a femoropopliteal bypass for continuing ischemia. Intravascular ultrasound imaging allowed accurate, sequential, on-line calculation of the cross-sectional area and volume of the lesion both, acutely and following healing of the site. The morphology of the fractured arterial plaque was clearly defined, demonstrating distribution of calcification, and intraluminal flaps not apparent on arteriography. The case demonstrates the unique potential of intravascular ultrasound in assessing the immediate effect of interventions and evaluating the long-term healing.