Left ventricular ejection fraction (biplane volumes)= [(end-diastolic - end-systolic) / end-diastolic] x 100 (%) Ejection Fraction（EF）. The left ventricle is a chamber which relaxes to fill with blood and then contracts to pump the blood out. Even in a healthy heart, the left ventricle does not pump all of the blood out with each beat. The ejection fraction is defined by the following formula: 左心在舒张时容纳大量血液，然后再收缩时将这些血液博出。即使正常的心脏，左室也不可能在每次搏动时将其内的血液完全博出。射血分数（EF）的定义公式如下：  The ejection fraction is a useful measure of left ventricular
performance. The normal range is 63-77% for males and 55-75% for
females (reference: Measurements in Cardiology). If the left ventricle wall is thinned, a decrease in the ejection fraction is seen. EF是检测左室功能的一个常用指标。EF的正常值对于男性在63%~77%之间，女性在55%~75%之间。如果左室壁变薄，EF可能会继而降低。   2D examination of the left ventricle Normal systolic function and segmental wall kinesis. Left panel: apical 4-chamber view.
Clockwise: interventricular septum, apex and antero-lateral wall. Note consistent (normal) systolic descent of
the cardiac base (i.e., mitral anulus) towards the apex of the left
ventricle (> 1 cm). Left ventricular dilatation and systolic dysfunction (biplane ejection fraction= 22.2 %). Compare with normal findings above. Extensive segmental wall motion abnormalities. The apex is dilated and akinetic. The interventricular septum, infero-posterior wall and distal anterior wall are akinetic. Note also reduced systolic descent of the cardiac base (i.e., mitral anulus) towards the apex of the left ventricle (< 0.8 cm)
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