K.Wayne Johnston

Intraabdominal hemorrhage as a result of segmental mediolytic arteritis of an omental artery: Case report *

This article describes the fifth reported case of segmental mediolytic arteritis and the second in a survivor. The patient had intraabdominal bleeding as a result of a ruptured omental artery. The pathologic and arteriographic findings are described. The pathology is characterized by segmental disruption of the medial smooth muscle cells and the initiation of mediolysis. Mediolysis is associated with marked segmental thinning of the vessel wall, often with only the adventitia intact. Fibrin is deposited at the adventitial and medial surfaces, and hemorrhage into the media may occur. As in this reported case, lysis of the adventitia leads to sudden, often catastrophic intraabdominal hemorrhage. Little associated adventitial inflammation occurred. Segmental mediolytic arteritis seems to involve the intra-abdominal muscular arteries in elderly patients with nonspecific abdominal symptoms. An angiogram showed patchy areas of narrowing involving ileal, gastroduodenal, and renal arteries that correlated with the pathologic findings observed in the excised omental arteries.

Expanded PTFE Prostheses as Arterial Substitutes in Humans: Late Pathological Findings in 73 Excised Grafts

Through collaboration of surgeons, pathologists and bioengineers at five centers in Canada and France, this study analyzed the late pathology and structural changes in 73 expanded PTFE arterial prostheses harvested from patients at autopsies and reoperations. The degree of tissue encapsulation increased with the duration of implantation but was reduced by the presence of infection. In several cases, the fibrous tissue penetrated the wall of the prosthesis and partitioned off the thin outer layer, thus disrupting the delicate microporous structure of the wall. The presence of aneurysms was observed in models that had no external reinforcing layer and among grafts that apparently suffered from surgical trauma. Wrinkling of grafts was noted at areas of flexion and was often associated with thickening of the external capsule and reduced luminal diameters. Endothelialization was found within only a few millimeters of the anastomoses. The luminal surfaces were generally not well healed. The PTFE structure was usually readily visible under a thin covering of loosely adhering thrombotic deposits. Bacteria were observed in 46% of the cases, even though only 29% were considered clinically infected. The incidence of lipid or cholesterol deposits was high. Avoiding iatrogenic trauma to the external wall of the prosthesis during implantation is important. Those features where design improvements are required to provide longer term structural integrity and dimensional stability in future models of expanded PTFE prostheses should be identified.

Use of interventional procedures for peripheral arterial occlusive disease in Ontario between 1991 and 1998: a population-based study

PURPOSEnAlthough peripheral arterial occlusive disease (PAOD) is a public health issue in the elderly population, limited population-based data are available on use of interventional procedures in Canada. We describe trends in use of interventional procedures to treat PAOD in Ontario over the past decade.nnnMETHODSnA retrospective population-based cohort study was conducted for fiscal years 1991 to 1998 with Ontario administrative databases to identify all arterial bypass surgeries, angioplasty procedures, and amputations performed.nnnRESULTSnA total of 19,332 bypass operations, 16,334 angioplasty procedures, and 17,534 amputations were identified. Population-based rates showed that angioplasty use peaked at about 110 per 100,000 at age 65 to 74 years, arterial bypass surgery use peaked at 129 per 100,000 at age 75 to 84 years, and amputation use peaked at 138 per 100,000 at age 85 years or older. All types of interventional procedures to treat PAOD were performed more frequently in men than in women. Age-adjusted and sex-adjusted rate of arterial bypass surgery decreased significantly, from 77 to 61 per 100,000 population aged 45 years or older (P =.0002, linear regression analysis), whereas rate for PTA increased significantly, from 59 to 75 per 100,000 population aged 45 years or older (P =.0005). The overall major amputation rate declined slightly over the study period, influenced by the decreased rate in patients aged 85 years or older. The revascularization rate in patients aged 85 years or older increased (P =.055).nnnCONCLUSIONnReduced use of arterial bypass surgery and increased use of angioplasty procedures has occurred over the past decade and may reflect a change in the practice pattern of vascular surgeons in Ontario, who have become more conservative in treating localized disease and reserve surgical interventions for more severe forms of PAOD. The slight reduction in overall major amputation rate, driven by decreased rate in patients aged 85 years or older, may reflect a trend toward a more aggressive revascularization approach in this age group.

Percutaneous Transluminal Angioplasty of Abdominal Aortic Stenoses

Percutaneous transluminal angioplasty (PTA) was performed on 25 patients with localized distal abdominal aortic stenoses. All patients were smokers and all complained of bilateral lower limb claudication. Eleven patients had small distal aortas and iliac vessels. Technically successful dilatation was achieved in all patients. Long-term follow-up was available on 17 of the patients. The mean follow-up period was 38 months. Cumulative patency at 5 years was 70%. Thirteen patients remain asymptomatic 15–83 months following PTA. Late failure occurred in 4 patients, 1–38 months following PTA. No complications related to PTA were experienced. PTA of localized aortic stenoses is a safe alternative to surgery and should be the treatment of choice in this condition.

Outcome of revascularization procedures for peripheral arterial occlusive disease in Ontario between 1991 and 1998: a population-based study

PURPOSEnWe describe the outcome of revascularization procedures used to treat peripheral arterial occlusive disease (PAOD), using population-based administrative data.nnnMETHODSnA retrospective population-based cohort study utilizing administrative databases in Ontario, Canada, was conducted for fiscal years 1991 to 1998 to identify patients who underwent arterial bypass surgery and percutaneous transluminal angioplasty to treat PAOD. The Kaplan-Meier method was used to calculate cumulative survival rate and amputation-free survival rate. To analyze factors that affect these rates, multivariate analysis was performed with Cox proportional hazard models.nnnRESULTSnOver the study period 15,824 patients underwent bypass operations and 11,548 underwent angioplasty. For patients who underwent bypass surgery, 5-year cumulative survival rate was 61.5% and major amputation-free survival rate was 83.4%, compared with 69% and 92.2%, respectively, for patients who underwent angioplasty. Male sex, older age, diabetes, and heart disease were associated with increased risk for death after revascularization procedures. Increased risk for major amputation after revascularization procedures was associated with male sex, older age, and diabetes, whereas hypertension was linked to decreased risk.nnnCONCLUSIONnTo evaluate the long-term outcome of revascularization procedures for PAOD at the population level, survival and major amputation-free survival rates should be used, because they provide more clinically accepted estimates compared with the correlation between utilization rates for revascularization and amputation procedures, which have been used to describe outcome in previously published reports in the literature.

Human Saphenous Vein Coronary Artery Bypass Graft Morphology, Geometry and Hemodynamics

Coronary artery bypass graft (CABG) failure has been linked to graft hemodynamics, in particular wall shear stress. This study characterizes the morphology, geometry and wall shear stress patterns in human CABGs. The intimal thickness (IT) in 49 human saphenous vein CABGs was measured by digital light microscopy. The geometry of six saphenous vein CABGs was replicated by post-mortem infusion of Batson’s #17 anatomical corrosion casting compound. Graft hemodynamics were evaluated in two flow models, fabricated from the casts, under steady (Re = 110) and pulsatile flow (Re = 110, α = 2) conditions. Saphenous vein CABGs in situ for more than 2 months had, on average, the greatest IT on the hood and suture sites of the distal anastomosis. Floor thickening was highly variable and significantly less than IT at the hood, suture site and graft body. All casts showed an indentation along the floor and 5/6 casts displayed a sharp local curvature on the hood. In both flow models, a large increase in wall shear rate occurred on the hood, just proximal to the toe. The local geometry of the hood created this large spatial gradient in wall shear stress which is a likely factor in hood intimal hyperplasia.

Difficulty in Assessing the Severity of Aorto-Iliac Disease by Clinical and Arteriographic Methods

Accurate hemodynamic assessment of the severity of aorto-iliac disease has important implications in the management of patients with symptomatic peripheral arterial occlusive disease. This study has documented that history, clinical examination, and single-plane angiography are often unsatisfactory for assessing the hemodynamic significance of an aorto-iliac lesion. The use of oblique angiographic views, certain noninvasive methods, such as quanti tative Doppler waveform analysis, and direct pressure measurements will be of benefit in difficult cases and lead to a more accurate diagnosis.

Pathologic features of surgically excised human umbilical vein grafts.

This article describes the pathologic changes in 31 human umbilical vein grafts excised from 23 patients after implantations ranging from 24 hours to 5 years. Gross morphologic examination, light microscopy, and scanning electron microscopy demonstrated that the umbilical vein grafts appeared to be fragile and easily delaminated. Bacteremic colonization on the luminal surface was present in the grafts removed because of infections but in two instances had extended into the wall. The presence of lipid on the surface and in the subintimal layer was observed in five grafts, three of which had been implanted for less than 1 month. We concluded that human umbilical vein grafts pathologically exhibit fragility, biodegradation, lipid accumulation, and bacterial colonization in infected cases, and these characteristics may adversely affect the durability and long-term success of the prosthesis.

The Society for Vascular Surgery—State of the Society, 2008

Does the Society for Vascular Surgery (SVS) need to exist? This is a frank but reasonable question. A decade ago, many of us took for granted that vascular surgery was durable and unchanging. The specialty primarily dealt with major open surgery. But then things began to change. For many vascular surgeons, the past decade or more been has insecure and uncertain for a number of reasons. Many of us were slow to recognize and embrace the changes that were occurring in our specialty and to provide comprehensive vascular care, including minimally invasive and open surgery. It has taken a decade to learn and practice the new interventional skills and to show our referring doctors that we are a changed specialty. We are among the smallest of the specialties and we were divided. We didn’t always listen well to each other, we didn’t understand each others’ views, and for a time we didn’t work together. During this time, cardiologists, interventional radiologists, and cardiothoracic surgeons increasingly began treating vascular diseases. As a result of these and other factors during the past decade of change, we began losing our independent identity as the vascular specialists.

Errors and Artifacts of Carotid Ultrasound Evaluation

This chapter covers the errors than can be made in the ultrasound evaluation of carotid artery disease and suggests approaches to minimize them. The following are discussed: inter-technologist variability, inconsistent definition of percent stenosis or application of diagnostic criteria, incorrect angle of insonation, clinical situations affecting peak systolic velocity (PSV) measurements, sample volume not positioned at the site of maximum stenosis to record PSV, confusing internal and external carotid arteries, lesion obscured by acoustic shadowing, patient factors, and other artifacts.