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Biomedical subjects

Samuel Siu

Publications and source records attributed to Samuel Siu.

8 recordsLinked to original sources
PubMed2005

Clinical and echocardiographic determinants of long-term survival after surgical myectomy in obstructive hypertrophic cardiomyopathy.

BACKGROUND: Surgical myectomy has been the standard treatment for patients with drug-refractory obstructive hypertrophic cardiomyopathy. The clinical and echocardiographic predictors of long-term survival and freedom from cardiovascular morbidity after myectomy have been unclear. METHODS AND RESULTS: We studied a consecutive cohort of 338 adult patients (age at operation 47+/-14 [range 18 to 77] years, 60% male) who underwent myectomy at our institution. Preoperative resting left ventricular outflow tract (LVOT) gradient was 66+/-32 mm Hg (range 5 to 158 mm Hg). Early postoperative mortality was 1.5% (5 deaths): 4 deaths occurred between 1978 and 1992, and 1 death occurred between 1993 and 2002. During long-term follow-up, 83% of patients reported an improvement to functional class I or II. The majority of patients (98%) had no resting LVOT gradient. Long-term survival was excellent, with 98+/-1% survival at 1 year, 95+/-1% at 5 years, and 83+/-3% at 10 years after myectomy. Multivariable Cox regression analysis identified 5 predictors of overall mortality: (1) age > or =50 years at surgery (hazard ratio [HR] 2.8, 95% CI 1.5 to 5.1, P=0.001), (2) female gender (HR 2.5, 95% CI 1.5 to 4.3, P=0.0009), (3) history of preoperative atrial fibrillation (HR 2.2, 95% CI 1.2 to 4.0, P=0.008), (4) concomitant CABG (HR 3.7, 95% CI 1.7 to 8.2, P=0.001), and (5) preoperative left atrial diameter > or =46 mm (HR 2.9, 95% CI 1.6 to 5.4, P=0.0008). Significant predictors of late major cardiovascular events found on multivariable analysis were (1) female gender (HR 3.3, 95% CI 2.0 to 5.4, P<0.0001), (2) history of preoperative atrial fibrillation (HR 1.9, 95% CI 1.1 to 3.3, P=0.02), and (3) preoperative left atrial diameter > or =46 mm (HR 2.5, 95% CI 1.5 to 4.3, P=0.0008). CONCLUSIONS: Myectomy provides excellent relief for LVOT obstruction in patients with hypertrophic cardiomyopathy. Preoperative clinical and echocardiographic variables can predict long-term outcome after myectomy.

Adolescent↗
PubMed2005

Guidelines for the provision of echocardiography in Canada: recommendations of a joint Canadian Cardiovascular Society/Canadian Society of Echocardiography Consensus Panel.

Recognizing the central role of echocardiographic examinations in the assessment of most cardiac disorders and the need to ensure the provision of these services in a highly reliable, timely, economical and safe manner, the Canadian Cardiovascular Society and Canadian Society of Echocardiography undertook a comprehensive review of all aspects influencing the provision of echocardiographic services in Canada. Five regional panels were established to develop preliminary recommendations in the five component areas, which included the echocardiographic examination, the echocardiographic laboratory and report, the physician, the sonographer and indications for examinations. Membership in the panels was structured to recognize the regional professional diversity of individuals involved in the provision of echocardiography. In addition, a focus group of cardiac sonograhers was recruited to review aspects of the document impacting on sonographer responsibilities and qualification. The document is intended to be used as a comprehensive and practical reference for all of those involved in the provision of echocardiography in Canada.

Canada↗
PubMed2004

Cardiovascular problems and pregnancy: an approach to management.

Women with some congenital or acquired heart lesions are at increased risk for a number of maternal and neonatal complications during pregnancy. Knowing what constitutes high risk and when to refer to a specialty clinic are key to successfully managing such patients.

Cardiomyopathies↗
PubMed2002

Heart failure and ventricular dysfunction in patients with single or systemic right ventricles.

BACKGROUND: Previous studies suggested a high incidence of congestive heart failure in patients with single and/or systemic right ventricles. The corresponding risk in an adult population is unknown. METHODS AND RESULTS: A cohort of 188 consecutive adult patients with single or systemic right ventricles was prospectively assessed with gated radionuclide angiography (n=135) or 2D echocardiography (n=188) and followed up clinically. Clinical assessment showed 82.4% of the patients were in New York Heart Association class I or II, 13.3% were in class III, and 4.3% were in class IV. Heart failure occurred in 22.2% of patients with transposition of the great arteries and a Mustard procedure, 32.3% of patients with congenitally corrected transposition of the great arteries, and 40% of Fontan-palliated patients. Symptomatic patients had significantly lower anaerobic thresholds (10.3 +/- 2.8 versus 13.2 +/- 4.8 mL center dot kg(-1) center dot min(-1), P=0.006) and peak (center dot)VO(2) (15.2 +/- 4.8 versus 20.3 +/- 6.8 mL center dot kg(-1) center dot min(-1), P<0.00029). Systemic ventricular ejection fraction in symptomatic versus asymptomatic patients at rest was 34.8 +/- 15.7% versus 46.7 +/- 13.4% (P=0.00001). Mortality was 47.1% among symptomatic patients and 5% among asymptomatic patients at 15.7 years of postoperative follow-up. Seven of 12 patients with potentially correctable surgical lesions died or persisted in heart failure despite surgery. Best predictors for mortality were New York Heart Association class, systemic ejection fraction, and age at operation. CONCLUSIONS: Patients with single or systemic right ventricles have significant risk for heart failure accompanied by high mortality. This study suggests the importance of identifying this group of patients who are at risk for heart failure and considering strategies to preserve ventricular function.

Adolescent↗
PubMed2002

Economic impact of contrast stress echocardiography on the diagnosis and initial treatment of patients with suspected coronary artery disease.

OBJECTIVE: To estimate the impact of contrast stress echocardiography on resource use in the treatment of patients with suspected coronary artery disease (CAD). METHODS: Fifty-nine patients with suspected CAD underwent nuclear perfusion imaging and contrast echocardiography examination. Further treatment was planned after each test and a final treatment was recommended after reviewing the results of both examinations. Medical resources and productivity losses were then collected for a 3-month follow-up period. RESULTS: Diagnosis was possible in 96.6% of patients with nuclear perfusion imaging and 93.2% with contrast echocardiography, resulting in a cost per successful diagnosis of $637 (Can) and $476 (Can), respectively. For the majority of patients (74%), both tests provided the same result, but for 12 patients nuclear imaging suggested abnormal perfusion, whereas contrast echocardiography indicated normal function and for 2 patients it was the opposite situation. Per-patient costs for the total patient population decreased from $316 (Can) after nuclear perfusion imaging to $250 (Can) when results from both tests were known. Three-month follow-up societal costs were $441 (Can) per patient, with hospitalization contributing 58% of this total cost. CONCLUSION: Contrast echocardiography has a similar success rate to nuclear perfusion imaging in diagnosing CAD, but has a 28% lower cost and has the potential of additional cost savings through the elimination of further diagnostic tests.

Aged↗
PubMedDate not supplied

Papillary fibroelastoma of the interatrial septum: a case report.

Primary cardiac tumors are rare, with benign lesions outnumbering malignant ones by a margin of over four to one. Amongst the benign cardiac neoplasms, papillary fibroelastomas are reported second only to myxomas. Papillary fibroelastomas commonly rise from heart valves and their size ranges from a few millimeters to well over 2.0 cm in diameter. While myxomas commonly arise from the interatrial septum, we present the rare example of a large papillary fibroelastoma arising from the left side of the interatrial septum.

Coronary Angiography↗
PubMedDate not supplied

Thrombosis of mechanical mitral valve prosthesis.

Obstruction of mechanical valve prostheses is a rare but potentially lethal complication following valve replacement surgery. Identifying the etiology and differentiation between thrombus, pannus, and vegetation obstructing the valve prosthesis can pose a diagnostic challenge. We report a patient who had an acute cerebral hemorrhage, developed a progressive mass lesion obstructing his mechanical mitral valve, and discuss contemporary diagnostic and management strategies.

Cerebral Hemorrhage↗