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A handbook for clinical practice - part 2

Không đóng trình duyệt đến khi xuất hiện nút TẢI XUỐNG Tải xuống

Tỷ lệ đột tử do tim (SCD) được báo cáo là khoảng 300 000-400 000 trường hợp tử vong hàng năm ở Hoa Kỳ tùy thuộc vào định nghĩa được sử dụng (xem Chương 1). Mặc dù nguyên nhân thường gặp nhất gây tử vong là bệnh động mạch vành | CHAPTER 2 Genetic predisposition and pathology of sudden cardiac death Xavier Jouven Allen P. Burke and Renu Virmani Introduction The incidence of sudden cardiac death SCD is reported to be approximately 300 000-400 000 deaths yearly in the United States depending upon the definition used see Chapter 1 . Although the most frequent cause of death is coronary artery disease there is a variety of underlying substrates for fatal ventricular arrhythmias and there is a complex interaction between genetic and environmental factors regardless of the underlying cardiac disease. A precise knowledge of the morphology risk factors and genetic basis of a large series of SCDs is necessary to expand our understanding and therefore ability to prevent this common yet catastrophic event. Definition of SCD and proportion of unexpected natural deaths that are cardiac in origin Sudden cardiac death is defined as natural unexpected death due to cardiac causes that occurs within a short time after the onset of acute symptoms usually instantaneous or within 1 h from the onset of symptoms to cardiac arrest 1 . When the definition for sudden death includes duration of symptoms of less than 1 h between onset and death 91 of unexpected natural deaths are due to cardiac arrhythmias. Kuller and colleagues showed that when the definition is expanded to include deaths with symptoms occurring up to 2 h before death 12 of deaths were sudden and 88 were due to cardiac causes. However when the duration of symptoms was increased to 24 h 32 of deaths were sudden and cardiac cause of death declined to 75 2 3 . Therefore the stricter the definition of sudden instantaneous death the smaller the proportion of natural deaths that are sudden as would be expected but the higher the rate that are cardiac in origin as opposed to deaths due to internal strokes hemorrhages embolic phenomena and other noncardiac events. 21 22 Chapter 2 Causes of SCD Virtually any pathologic process that involves the heart may lead