title: Assessment of cardiac function and synchronicity in subjects with isolated bundle branch block using Doppler imaging.
abstract: BACKGROUND
  Using tissue Doppler imaging and conventional echocardiographic technique, we examined the cardiac function and synchronicity in individuals with isolated right bundle branch block (RBBB) or left bundle branch block (LBBB) and assessed the relationship between QRS duration and synchronicity.
  
  
  METHODS
  Subjects with isolated RBBB (n = 20), LBBB (n = 10) and normal controls (n = 20) were studied with conventional echocardiography and tissue Doppler imaging. The difference between aortic and pulmonary preejection intervals was defined as interventricular delay. Parameters in septum and lateral wall were measured using tissue Doppler imaging, including peak sustained systolic velocity (S(M)), peak early (E(M)) and late (A(M)) diastolic velocities as well as time to peak velocities (T(S), T(E) and T(A)).
  
  
  RESULTS
  Subjects with LBBB had lower S(M) and longer T(S) than did the RBBB and control groups (P < 0.05, P < 0.001 respectively). A significant difference was observed in E(M), being the lowest in the LBBB and the highest in the control group (P < 0.05). Moreover, T(E) was longer in the LBBB group compared with the other two groups (P < 0.001). Both A(M) and T(A) were similar among three groups (P > 0.05). In the bundle branch block groups, one ventricle lagged about 40 ms behind the other. A significant correlation was found between interventricular delay and QRS duration (r = 0.713, P < 0.001).
  
  
  CONCLUSIONS
  Cardiac ventricles were not well synchronized with one ventricle lagging about 40 ms behind the other in subjects with LBBB or RBBB, even though only LBBB group showed barely perceptible, impaired cardiac function. In addition, QRS duration and cardiac asynchronicity were positively correlated.
authors.affiliation: Centre of Arrhythmia Diagnosis and Treatment, Fuwai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
authors.forename: Hong-xia
authors.initials: HX
authors.lastname: Niu
authors.forename: Wei
authors.initials: W
authors.lastname: Hua
authors.forename: Shu
authors.initials: S
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Sun
authors.forename: Fang-zheng
authors.initials: FZ
authors.lastname: Wang
authors.forename: Ke-ping
authors.initials: KP
authors.lastname: Chen
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003971:Diastole; D015150:Echocardiography, Doppler / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013599:Systole