Chan Peter G, Logue Michael, Kligfield Paul
Division of Cardiology, Department of Medicine, Weill Medical College of Cornell University, The New York-Presbyterian Hospital, New York, NY 10021, USA.
Ann Noninvasive Electrocardiol. 2006 Jul;11(3):230-6. doi: 10.1111/j.1542-474X.2006.00108.x.
Although right bundle branch block (RBBB) delays right ventricular depolarization, its effect on cancellation of right and left ventricular forces within the QRS complex has not been quantified during stable temporal and physiological conditions. Systematic changes in QRS amplitude during transient RBBB bear directly on performance of standard ECG criteria for left ventricular hypertrophy (LVH), and these changes require quantification.
We examined the instantaneous effect of RBBB on QRS amplitudes and LVH voltages in 40 patients who had intermittent complete RBBB during a single 10 sec standard 12-lead ECG recording, comprising 0.1% of approximately 400,000 consecutive ECGs in a university teaching hospital setting. Amplitudes were measured by magnifying graticule to the nearest 25 microvolts, averaged for up to 3 normal and 3 RBBB complexes, and compared by paired t test.
RBBB was associated with an increase in initial QRS forces (RV1, RV2, and QV6) but significant decreases in mean mid-QRS amplitudes that reflect left ventricular depolarization (RaVL [-75 microvolts], SV1 [-389 microvolts], SV3 [-617 microvolts], RV5 [-100 microvolts], and RV6 [-123 microvolts]). All late QRS forces were increased with RBBB (R'V1, SV5, SI). As a result, combined voltages used for LVH criteria were significantly reduced by RBBB: Sokolow-Lyon voltage decreased from 1520 +/- 739 to 1014 +/- 512 microvolts (p < 0.001), and Cornell voltage decreased from 1438 +/- 683 to 746 +/- 399 microvolts (p < 0.001).
RBBB is associated with significant reduction in "left ventricular" QRS amplitudes of the standard ECG, consistent with cancellation, rather than unmasking, of left ventricular mid-QRS forces by altered septal and delayed right ventricular depolarization. Because QRS voltages that are routinely combined for the detection of LVH are reduced in RBBB, standard LVH criteria will perform with lower sensitivity in patients with RBBB.
尽管右束支传导阻滞（RBBB）会延迟右心室去极化，但在稳定的时间和生理条件下，其对QRS波群内左右心室力量抵消的影响尚未得到量化。短暂性RBBB期间QRS波幅的系统性变化直接关系到左心室肥厚（LVH）标准心电图标准的表现，这些变化需要量化。
我们在40例患者的单次10秒标准12导联心电图记录中检查了RBBB对QRS波幅和LVH电压的即时影响，这些患者存在间歇性完全性RBBB，占一所大学教学医院环境中约40万份连续心电图的0.1%。通过将放大标尺放大到最接近的25微伏来测量波幅，对多达3个正常和3个RBBB波群进行平均，并通过配对t检验进行比较。
RBBB与初始QRS波力量（RV1、RV2和QV6）增加相关，但反映左心室去极化的平均QRS波群中部波幅显著降低（RaVL[-75微伏]、SV1[-389微伏]、SV3[-617微伏]、RV5[-100微伏]和RV6[-123微伏]）。所有晚期QRS波力量在RBBB时均增加（R'V1、SV5、SI）。结果，用于LVH标准的组合电压因RBBB而显著降低：索科洛夫-里昂电压从1520±739微伏降至1014±512微伏（p<0.001），康奈尔电压从1438±683微伏降至746±399微伏（p<0.001）。
RBBB与标准心电图中“左心室”QRS波幅显著降低相关，这与间隔改变和右心室延迟去极化对左心室QRS波群中部力量的抵消而非掩盖一致。由于RBBB中常规用于检测LVH的QRS波电压降低，标准LVH标准在RBBB患者中的敏感性将降低。
