Publications by authors named "Shaun Leong"

A 27-year-old man who received a HeartMate (Thoratec Corporation, USA) left ventricular assist device for progressive heart failure as a bridge to orthotopic heart transplantation is described in the present report. The device failed (mechanical failure) after almost 19 months. The porcine bioprosthetic valves in the inflow and outflow cannulae showed hemorrhage, cusp tears and inflammatory cells, located largely on the inflow valve cusps.

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Cocaine is a powerful stimulant that gives users a temporary sense of euphoria, mental alertness, talkativeness, and a decreased need for food and sleep. Cocaine intoxication is the most frequent cause of drug-related death reported by medical examiners in the US, and these events are most often related to the cardiovascular manifestations of the drug. Once playing a vital role in medicine as a local anesthetic, decades of research have established that cocaine has the ability to cause irreversible structural damage to the heart, greatly accelerate cardiovascular disease, and initiate sudden cardiac death.

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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.

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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.

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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.

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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.

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Background: Inflammatory myofibroblastic tumor (IMT) of the heart is extremely rare with unpredictable clinical expression. IMTs, characterized by spindle cells, plasma cells, and a polymorphic inflammatory infiltrate, have a predilection for children and young adults. Clinically, IMT mimics malignancy, making a definitive diagnosis difficult, prior to histopathological examination.

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Background: The Medtronic Freestyle valve is fixed in glutaraldehyde at zero pressure on the cusps and treated with alpha-amino oleic acid. This valve reportedly has excellent clinical and hemodynamic results, but little has been reported about its long-term pathology.

Methods And Results: Nine Freestyle valves explanted between 2003 and 2005 were reviewed to assess the reasons for bioprosthesis failure (six implanted at our institution).

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We report the longest duration of implantation of a porcine bioprosthesis in the English language literature--a Carpentier-Edwards valved conduit excised after twenty-five years. This 50-year-old man had undergone a modified Fontan operation for tricuspid atresia. He presented with progressive dyspnea, fatigue and edema.

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Heart valve bioprostheses can undergo early post-implantation changes, including pannus and thrombus, which may be hastened by the presence of a left ventricular assist device (LVAD). We report the case of a 21 year-old male who was diagnosed with dilated cardiomyopathy and severe aortic insufficiency, and had his aortic valve replaced with a #25 BioPhysio valve (currently in clinical trials--Edwards Life Sciences, Irvine, CA, USA). His symptoms of congestive heart failure continued to worsen, and he received a Novacor LVAD (WorldHeart, Oakland, CA, USA), and subsequently, an orthotopic heart transplantation.

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Background: Bioprosthetic heart valves are more frequently being used in valve replacement procedures today. Although second-generation bioprosthetic valves have improved functionality over their first-generation counterparts, they still often fail due to primary tissue degeneration.

Methods: This study examines two second-generation porcine valves after surgical explantation, the Hancock-II (HAN; Medtronic Heart Valve Division, Irvine, CA, USA) and the Carpentier-Edwards supraannular (CE-SAV; Baxter Healthcare Corporation, now Edwards LifeSciences, Irvine, CA, USA), with special attention to morphological/histological changes and reasons for valve failure.

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Infective endocarditis (IE) usually involves the left-sided valves, and IE involving the tricuspid valve (TV) is rare, often developing in intravenous drug users (IDU). We present a case of a 32-year-old male, an intravenous drug abuser (IDA), who presented with nonspecific septic symptoms, and was treated with TV conserving surgery. Pathological examination confirmed tissue destruction, friable thrombotic vegetations, and microorganisms in the leaflet tissue.

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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.

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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.

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Background: Primary cardiac sarcoidosis (CS) is rare, and concomitant involvement of the coronary arteries is rarer still. Successful diagnosis of this disease is difficult due to its nonspecific symptoms which mimic those of idiopathic dilated cardiomyopathy (IDCM).

Methods And Results: We describe a 47-year-old Caucasian male who underwent orthotopic heart transplant for presumed IDCM.

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Aneurysms of the coronary arteries are uncommon occurrences that usually develop secondary to atherosclerosis and are often asymptomatic. They are usually diagnosed incidentally during investigation for ischemic heart disease or at autopsy for sudden death. We present a case of a "giant" right coronary artery aneurysm (CAA) discovered incidentally at surgery.

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Aortic valve disease is an increasingly common medical problem in the 20th century; however, its pathogenesis is poorly understood. The present paper reviews 247 cases of aortic valves surgically excised over a one-year period, with special attention to the morphological and histological changes observed in surgically excised aortic valves, and to how those changes relate to the mechanisms of valve failure. Patient age ranged from 17 to 86 years, with a mean of 64.

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Introduction: Cardiac neoplasms are rare and the vast majority are metastatic in origin. Symptoms of cardiac neoplasms (primary or metastatic) usually appear late in the course of the disease and are often ignored because of the more severe effects of the primary malignant disorder or its therapy. Consequently, cardiac neoplasms, especially metastatic ones, are often not discovered until autopsy.

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