Burggraf G W
Circulation. 1981 Feb;63(2):429-35. doi: 10.1161/01.cir.63.2.429.
To examine the nature of the first heart sound in left bundle branch block (LBBB), 26 patients with LBBB were studied using echophonocardiography. Apexcardiograms and systolic time intervals were also obtained from these patients and the results were compared with 20 normal subjects. Mitral closure preceded tricuspid closure by 0.02-0.04 second in 19 of the 20 normal subjects. In contrast, in subjects with LBBB there was a variable delay in mitral closure so that in seven subjects the sequence of mitral and tricuspid closure was normal, in 11 it was reversed compared wih the normal group, and in eight closure of both valves was simultaneous. The interval from the onset of ventricular depolarization to mitral closure was 0.074 +/- 0.019 (mean +/- SD) for the patients with LBBB and 0.057 +/- 0.008 second for the normal group (p < 0.001). With LBBB the first sound tended to be of reduced intensity and separate mitral and tricuspid components could not be identified. Systolic time intervals and the apexcardiograms demonstrated a delayed onset of left ventricular contraction and an increased isometric contraction time in the LBBB group, both of which would contribute to a delayed mitral valve closure and decreased first heart sound intensity.
为研究左束支传导阻滞（LBBB）时第一心音的性质，对26例LBBB患者进行了超声心动图检查。同时获取了这些患者的心尖搏动图和收缩期时间间期，并将结果与20名正常受试者进行比较。20名正常受试者中有19名二尖瓣关闭比三尖瓣关闭提前0.02 - 0.04秒。相比之下，LBBB患者二尖瓣关闭存在不同程度的延迟，7名患者二尖瓣和三尖瓣关闭顺序正常，11名患者与正常组相比顺序相反，8名患者两个瓣膜同时关闭。LBBB患者从心室去极化开始到二尖瓣关闭的间期为0.074±0.019（平均值±标准差），正常组为0.057±0.008秒（p<0.001）。LBBB时第一心音强度往往降低，无法识别二尖瓣和三尖瓣的单独成分。收缩期时间间期和心尖搏动图显示LBBB组左心室收缩开始延迟，等容收缩时间延长，这两者都会导致二尖瓣关闭延迟和第一心音强度降低。
