左束支传导阻滞患者的冠状动脉造影分析

目的:研究左束支传导阻滞(LBBB)患者中冠状动脉受累情况。方法:回顾性分析术前常规心电图检出的195例LBBB患者冠状动脉造影和左室功能。结果:在63例左室射血分数(LVEF)≥50%的LBBB患者中,仅5例(8%)为左主干或3支血管病变;在132例LVEF<50%的患者中,仅18例(14%)为左主干或3支血管病变。结论:大多数LBBB的患者无左主干或3支血管病变,且与左室收缩功能无关。     

Hyperkalemic left bundle branch block and hyporeninemic hypoaldosteronism (hyperkalemic left bundle branch block)

A 70-year-old woman was admitted to the intensive coronary care unit with suspected myocardial infarction. During the follow-up period, the patient twice developed left bundle branch block, which was shown to be related to high serum potassium levels secondary to hyporeninemic hypoaldosteronism and moderate renal failure.     

Unmasking of left bundle branch potential in left bundle branch block during physiological pacing

Journal of Interventional Cardiac Electrophysiology -     

完全性左束支阻滞和右束支阻滞心电图结果分析

目的 了解完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.方法 分析108 610例常规心电图检测结果,分别统计完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.结果 108 610例门诊及住院患者资料,完全性左束支阻滞19例,占0.18％;右束支阻滞3 794例,占3.49％;完全性左束支阻滞发生率在不同性别之间差异无统计学意义（Х^2=1.707,P=0.191）,不同年龄之间比较差异有统计学意义（Х^2=209.874,P＜0.05）;右束支阻滞发生率在不同性别之间、不同年龄之间比较,差异均有统计学意义（Х^2=986.046,P＜0.05;Х^2=1 483.286,P＜0.05）.结论 60岁以上老年人的完全性左束支阻滞和右束支阻滞发生率较高,应定期进行常规心电图检查,及时发现异常情况并进行相应的处理.     

Left ventricular hypertrophy in left bundle branch block

The detection of left ventricular hypertrophy (LVH) in the presence of left bundle branch block (LBBB) remains a difficult clinical problem. Its prevalence and significance have not previously been studied in a group of living patients. M-mode echocardiography was utilized to determine the prevalence of anatomic LVH in 28 patients with LBBB. Various ECG and chest x-ray criteria as predictors of LVH were assessed. Anatomic LVH was present in 89% by echocardiography. A left atrial abnormality on ECG and a cardio-thoracic ratio greater than .50 were the best predictors of LVH. Hypertension and/or ischemic heart disease was present in 78.5% of the patients while only one patient was free of any evidence of cardiovascular disease.     

Exercise-induced left bundle branch block and its relation to coronary artery disease

The records of 2,584 consecutive patients who underwent both treadmill exercise testing and coronary cineangiography were reviewed to determine the relation between exercise-induced, acceleration-dependent left bundle branch block (LBBB) and the presence of coronary artery disease (CAD). Rate-dependent LBBB during exercise was identified in 28 patients (1.1%), who were categorized according to their presenting symptoms: classic angina pectoris, atypical chest pain, symptomatic cardiac arrhythmia and asymptomatic. Asymptomatic patients underwent a screening exercise test. CAD was present in 7 of 10 patients who presented with classic angina pectoris, but 12 of 13 patients presenting with atypical chest pain had normal coronary arteries. All 10 patients in whom LBBB developed at a heart rate of 125 beats/min or higher were free of CAD, whereas 9 of 18 patients in whom LBBB developed at a heart rate of less than 125 beats/min had CAD. Normal coronary arteries were present in 3 patients who presented with angina and in whom both chest pain and LBBB developed during exercise. It is concluded that patients who present with atypical chest pain in whom rate-dependent LBBB develops on the treadmill are significantly less likely to have CAD than patients who present with classic angina; the onset of LBBB at a heart rate of 125 beats/min or higher is highly correlated with the presence of normal coronary arteries, regardless of patient presentation; and patients with angina in whom both chest pain and LBBB develop during exercise may have normal coronary arteries.     

Functional anatomy of the canine left bundle branch

To elucidate the architecture of the left bundle branch, activation of Purkinje (P) and myocardial (M) cells of the canine left ventricular endocardial surface was mapped in vitro before and after lesions were placed in the proximal left bundle branch. Close bipolar electrodes or microelectrodes were employed to record P and M potentials by standard techniques. The left bundle branch has conspicuous and straight border fibers that continue as bridging strands to the papillary muscles. In addition, there is a less conspicuous network of serpentine interwoven fibers in the interior of the septal portion of the bundle that has interconnections with the border fibers. Below the mid-septum and over the free wall the P fibers form a densely interwoven network. The interior septal fibers are activated nearly simultaneously with equidistant points on the border fibers. The apparent conduction velocity of the border fibers was 1.8 m/sec as opposed to 1.45 m/sec in the interior network. The bridging strands provide a shortcut across the chamber to upper portions of the free wall and septum. The pattern of activation of M cells is represented by concentric rings with an island of earliest activation (at 15 to 25 msec) in the central septum. The M cells latest to be activated are at the tips of the papillary muscles and the upper septum below the valves. Interruption of one group of border fibers may delay by 5 to 8 msec activation of P and M cells of the upper paraseptal free wall and upper septum. Lesions in the interior network delay by 2 to 4 msec activation of the P and M cells of comparatively small areas of the septum. Activation of the mid-papillary free walls, the bases of the papillary muscles and the lower septum is not affected by proximal lesions partially interrupting the bundle branch. Transection of both groups of border fibers does not produce complete block. The left bundle branch is best represented as a fan-shaped network of interwoven fibers whose diverging border fibers are specialized for rapid, distant transport.