Towne W D, Patel R, Cruz J B, Mirrer B, Kramer N E
Cathet Cardiovasc Diagn. 1978;4(1):47-52. doi: 10.1002/ccd.1810040107.
A patient with a loud intermittent midsystolic click presented a problem in differential diagnosis between mitral valve prolapse (intracardiac origin of the click) and left pneumothorax (extracardiac origin). External phonocardiography performed at the time of cardiac catheterization revealed that this loud midsystolic click disappeared whenever a catheter was positioned across the mitral valve. It reappeared whenever the catheter was removed from the transmitral position. Selective left ventriculography confirmed the diagnosis of mitral valve prolapse.
一名有响亮的间歇性收缩中期喀喇音的患者，在二尖瓣脱垂（喀喇音的心内起源）和左气胸（喀喇音的心外起源）的鉴别诊断上存在问题。在心导管检查时进行的体外心音图检查显示，每当导管穿过二尖瓣时，这个响亮的收缩中期喀喇音就会消失。每当导管从二尖瓣位置移除时，喀喇音又会重新出现。选择性左心室造影证实了二尖瓣脱垂的诊断。
