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Heart murmurs are heart sounds produced when blood flows across one of the heart valves that is loud enough to be heard with a stethoscope. There are two types of murmurs. A functional murmur or "physiologic murmur" is a heart murmur that is primarily due to physiologic conditions outside the heart. Other types of murmurs are due to structural defects in the heart itself. Functional murmurs are benign (an "innocent murmur"). Murmurs may also be the result of various problems, such as narrowing or leaking of valves, or the presence of abnormal passages through which blood flows in or near the heart. Such murmurs, known as pathologic murmurs, should be evaluated by an expert. Heart murmurs are most frequently categorized by timing, into systolic heart murmurs and diastolic heart murmurs, differing in the part of the heartbeat on which they can be heard. However, continuous murmurs cannot be directly placed into either category. ==Classification== Murmurs can be classified by seven different characteristics: timing, shape, location, radiation, intensity, pitch and quality.〔(【引用サイトリンク】 Heart murmur: characteristics )〕 * Timing refers to whether the murmur is a systolic or diastolic murmur. * Shape refers to the intensity over time; murmurs can be (crescendo ), (decrescendo ) or crescendo-decrescendo. Crescendo murmurs progressively increase in intensity. Decrescendo murmurs progressively decrease in intensity. With crescendo—decrescendo murmurs (diamond or kite-shaped murmurs), a progressive increase in intensity is followed by a progressive decrease in intensity. * Location refers to where the heart murmur is usually heard best. There are four places on the anterior chest wall to listen for heart murmurs; each of the locations roughly corresponds to a specific part of the heart and should be listened to (through the stethoscope) with the patient lying down, face up. The four locations are: * * Aortic region - the 2nd right intercostal space. * * Pulmonic region - the 2nd left intercostal spaces. * * Tricuspid region - the 5th left intercostal space. * * Mitral region - the 5th left mid-clavicular intercostal space. :Additional maneuvers can be performed for additional auscultation: : * Left lateral decubitis. : * With the patient sitting upright. : * With the patient leaning forward and exhaling. * Radiation refers to where the sound of the murmur radiates. The general rule of thumb is that the sound radiates in the direction of the blood flow. * Intensity refers to the loudness of the murmur, and is graded according to the Levine scale, from 1 to 6: *# The murmur is only audible on listening carefully for some time. *# The murmur is faint but immediately audible on placing the stethoscope on the chest. *# A loud murmur readily audible but with no palpable thrill. *# A loud murmur with a palpable thrill. *# A loud murmur with a palpable thrill. The murmur is so loud that it is audible with only the rim of the stethoscope touching the chest. *# A loud murmur with a palpable thrill. The murmur is audible with the stethoscope not touching the chest but lifted just off it. * Pitch may be low, medium or high and is determined by whether it can be auscultated best with the bell or diaphragm of a stethoscope. * Quality refers to unusual characteristics of a murmur, such as blowing, harsh, rumbling or musical. A mnemonic to remember what characteristics to look for when listening to murmurs is SCRIPT: Site, Configuration (shape), Radiation, Intensity, Pitch and quality, and Timing in the cardiac cycle. The use of two simple mnemonics may help differentiate systolic and diastolic murmurs; PASS and PAID. ''P''ulmonary and ''a''ortic ''s''tenoses are ''s''ystolic while ''p''ulmonary and ''a''ortic ''i''nsufficiencies (regurgitation) are ''d''iastolic. Mitral and tricuspid defects are opposite.〔http://www.youtube.com/watch?v=4euNGIguluk Mnemonic tutorial video for cardiac murmurs〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Heart murmur」の詳細全文を読む スポンサード リンク
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