Shaun W. Leong

Coronary artery stents: identification and evaluation

First introduced in the 1980s, the coronary stent has been used to reduce the rate of arterial restenosis. Coronary stent implantation is currently a common procedure performed by interventional cardiologists, and the market for development and design is constantly expanding and evolving. This article was designed to assist pathologists in the accurate identification of coronary stents that are currently available, in addition to some that are no longer being implanted. The stents reviewed here were chosen based on frequency of use and/or occurrence in the literature. Some of the newer models have yet to undergo extensive clinical testing. The summaries accompanying each stent include concise physical descriptions and documented complications, intended to serve as a guide for the investigating pathologist.

Peripheral vascular disease: who gets it and why? A histomorphological analysis of 261 arterial segments from 58 cases.

Aims: This retrospective study aimed to document and illustrate the histomorphological changes underlying peripheral vascular disease (PVD). More specifically, it aimed to analyse and quantify those changes that lead to lower limb amputations. Histological changes were assessed in relation to various clinical pathologies, and significant correlations were sought thereafter. Methods: A total of 1305 arterial segments were examined from 58 consecutive patients undergoing a lower limb amputation from January 2002 to December 2003. Serial arterial segments were taken from the femoral, popliteal, anterior tibial, posterior tibial, peroneal, and dorsalis pedis arteries, and the degrees of atherosclerotic stenosis and medial calcification were histologically quantified. Results: Atherosclerosis was associated with severe arterial stenosis. An increased occurrence of severe atherosclerotic narrowing coincided with increasing patient age (p = 0.0166), hypertension (p = 0.0019), and diabetes mellitus (p = 0.0036). The presence of medial calcification was an important pathological feature in patients under 70 years of age (p = 0.0308) and significantly more severe in those with diabetes mellitus (p <0.001). Conclusion: Atherosclerosis and medial calcification are significant underlying lesions in diabetic patients undergoing lower limb amputation. Medial calcification can cause significant stiffening of the arterial wall and a reduction in its ability to respond to vasodilator stimuli.

Carpentier-Edwards Perimount Valves—Morphological Findings in Surgical Explants

Valvular heart disease is a growing medical problem in the 20th century, with an increasing number of patients undergoing valve repair and replacement surgery.1 Worldwide, more than 55% of implanted prosthetic heart valves (PHV) are mechanical heart valves (MHV) and 45% are bioprosthetic heart valves (BHV).2 BHV more closely resemble native valves in design than do mechanical valves, and are, therefore, better able to mimic normal blood flow patterns through a three-cusp valve.1 BHV may comprise porcine aortic tissue or bovine pericardium. The Carpentier-Edwards Perimount (CEP) bioprosthesis is a second-generation pericardial valve made of bovine (calf) pericardial tissue.1 The tissue is cut from selected regions of bovine pericardium and mounted on a lightweight Elgiloy frame covered with a porous, knitted polytetrafluoroethylene (PTFE) fabric. The sewing ring is made of molded silicone rubber covered with PTFE cloth, which enables the surgeon to sew the valve into place. Few studies have examined the postimplantation morphological changes in a series of explanted CEP. Herein, we describe such changes in 23 CEP valves, explanted at our institution since the start of their use in 1981.

Histological analysis of aortic dissections following previous cardiovascular surgery

BACKGROUND Aortic dissections have been reported as a rare complication post-cardiovascular surgery due to areas of cross clamping, suture lines and cannulation sites as locations for peri-operative injury. This study aimed to review the histological features of aortic tissues of 11 patients with aortic dissections who underwent previous cardiovascular surgery and to identify evidence of trauma within the area of surgery. METHODS A review of our records from January 2000 to July 2005 showed that 11 patients had developed a postoperative aortic dissection. Surgically excised aortic tissues were obtained either at surgery or at autopsy for further gross and histological analysis. Clinical records were also reviewed for relevant history. RESULTS The mean age of the 11 patients in this study was 60.1+/-12.5 years. The year of index surgery for all patients was between 1960 and 2005, and the interval between index surgery and admission for re-operation was 13.8+/-12.9 years (range, 1 day to 45 years). Five patients (45%) demonstrated aortic intimal thickening, two of which showed evidence of atherosclerotic plaques. Three (27%) exhibited cystic medial change. All cases showed mild to moderate medial changes near or at the site of traumatic injury, as demonstrated by a sharp discontinuity in the media of the aorta. Other than the four aortic tissues obtained at autopsy, long-term follow-up for the remaining patients was not obtained. CONCLUSION Evidence of previous trauma in close proximity to cannulation, cross-clamping and/or aortotomy sites was found in all patients in this series. All deaths in this series were found in the acute group rather than in the chronic group. It is important that the occurrence of dissections in patients undergoing previous cardiac surgery be not only reported, but analyzed by both the clinician and the pathologist. Hopefully, these efforts may identify particular patient risk factors and clarify preventative measures peri-operatively which may decrease the incidence of these potentially lethal complication.

Anomalous left coronary artery from the pulmonary artery: Case report and review of the literature

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is an uncommon occurrence, usually diagnosed at a young age. We report a 71-year-old patient who died suddenly of acute bilateral bronchopneumonia, and was found to have ALCAPA at autopsy. The patient had reported no cardiac symptoms during his lifetime. Autopsy revealed collateral connections between the left coronary artery (LCA) and right coronary artery (RCA), which were diffusely dilated, calcified and atherosclerotic.

Mitral valve-sparing procedures and prosthetic heart valve failure: a case report.

Prosthetic heart valve dysfunction due to thrombus or pannus formation can be a life-threatening complication. The present report describes a 47-year-old woman who developed valvular cardiomyopathy after chorda-sparing mitral valve replacement, and subsequently underwent heart transplantation for progressive heart failure. The explanted mitral valve prosthesis showed significant thrombus and pannus leading to reduced leaflet mobility and valvular stenosis. The present report illustrates the role of the subvalvular apparatus and pannus in prosthesis dysfunction.

Aortic stent grafts.

Abdominal aortic aneurysms (AAAs) occur when weakened areas of the abdominal aortic wall result in a ballooning of the blood vessel. Attributed risk factors include smoking, atherosclerosis and hypertension. Traditionally, AAAs were treated with open surgery, involving a large abdominal incision and the placement of a synthetic graft. The introduction of endovascular aneurysm repair (EVAR) however, proved to have many advantages over open repair, chief among which is a lower perioperative morbidity and mortality rate. EVAR is likely to continue to evolve and the complications associated with this procedure will likely continue to decrease. In the meantime, the benefit of the continued, detailed analyses of explanted devices is twofold: (1) for future development of new devices; and (2) cognisance of complications that arise with any new device. This review is a guide to the many FDA approved stents which are commercially available, and those likely to become available following clinical trials.

Morphological findings in 192 surgically excised native mitral valves

INTRODUCTION Mitral valve disease (MVD) is a significant clinical problem that is becoming more common in the 21st century. The pathogenesis of MVD seems to be changing and is not well understood. PATIENTS AND METHODS The present study details the morphological findings in 192 native mitral valves excised over a one-year period at the Toronto General Hospital, Toronto, Ontario. The mean patient age was 59.7+/-12.3 years at operation. RESULTS There were 106 men (55.2%) and 86 women (44.8%) in the present study. The most frequent changes in the surgically excised valvular leaflets were fibrosis (78.6%) and thickening (66.2%). Fusion (32.3%) and calcification (25.2%) were common changes at the commissures. Chordae tendineae most often showed evidence of thickening (47.9%) and fibrosis (37.0%). In total, 110 valves showed mitral incompetence (57.3%), 72 showed mitral stenosis (37.5%), and 10 showed a combination of stenosis and incompetence (5.2%). CONCLUSIONS In the present series, MVD was most frequently caused by postinflammatory (rheumatic) valve disease (RVD) (35.9%), followed by myxomatous degeneration (33.3%). Patients with RVD were usually female (66.7%), while those with myxomatous degeneration were more likely to be male (76.6%). RVD remains a significant problem even though the incidence of acute rheumatic fever with cardiac involvement has declined in Canada. This most likely reflects the current sociodemographic composition of the referral population.

The Role of Pannus in the Longevity of an Ionescu-Shiley Pericardial Bioprosthesis

Abstract  As the population ages, bioprosthetic heart valves are increasingly being used to replace diseased native valves. Bioprosthetic valve durability depends on patient age and other factors, but rarely exceeds 15 years. Explanted bioprosthetic valves commonly show tissue degeneration, tears, and calcification. Host tissue overgrowth (pannus), to the extent of interfering with their function, is another finding in bioprostheses that have been in place for long periods. We present a case in which a bovine pericardial valve was explanted after more than 20 years of implantation. The longevity of this pericardial valve may have been related to excessive pannus growth, which most likely protected the valve from earlier failure.

Pulmonary site bioprostheses: morphologic findings in 40 cases.

CONTEXT From January 1995 to June 2003, there were 514 patients who underwent pulmonary valve replacements at either the Hospital for Sick Children or Toronto General Hospital. Fifty-four (10.5%) of these adults returned for replacement of their prostheses because of failure. Forty (74.1%) of the 54 explants were bioprostheses, and 14 (25.9%) were homografts. OBJECTIVE To present the morphologic findings from this consecutive series of 40 pulmonary-site bioprostheses. DESIGN Data were obtained by review of pathologic, clinical, and surgical records for all 40 patients with bioprosthetic pulmonary valves explanted from 1995 to June of 2003. RESULTS The mean duration of valve implantation was 14.3 +/- 5.2 years (2-26 years). Median age at implantation was 16.7 +/- 10.3 years (range, 3 months to 53 years). Structural valve deterioration was found in 39 (97.5%) of the valves. Morphologic evidence of stenosis was found in all valves, whereas incompetence was found in 28 (70.0%). Calcification was present in 32 (80.0%) of the valves and was severe and diffuse in 22 (55.0%). Host tissue overgrowth, or pannus, was present on 39 (97.5%) of the valves and was severe in 35 (87.5%). Tears were present in 19 (47.5%) of the valves. CONCLUSIONS Explanted bioprostheses showed a high degree of calcification and pannus, which together led to stenosis. Cusp immobilization, involving all 3 cusps, was frequent and was more common in patients younger than 30 years of age at explantation (P < .001). Host-tissue overgrowth is a significant problem with bioprostheses, and pulmonary-site bioprostheses are no exception.