retrograde beat的用法和樣例：
例句
- Aex beat enlargement and left-downward displacement.
心尖搏動範圍擴大，向左下移位。 - On examination, he has a resting tachycardia and eidence of left entricular dilatation with a displaced apex beat and possible secondary mitral regurgitation.
體檢發現有靜息時心動過速與左心室擴大依據，心尖搏動偏移，可能有二尖瓣返流。
