At least 60% of the lesions can be characterised purely with ultrasound. To ensure patients do not become unnecessarily concerned, and to avoid further expensive examinations, or possible complications that can occur in the course of these examinations, it is important that as many as possible benign changes are also diagnosed. This happens when the heart rate reaches an elevated rate and becomes uncoupled from the refractory period, thus blocking the next electrical stimuli down the right bundle branch.Dr Antonius Schuster MD MBA is Head of the Department of Radiology at the LKH Bregenz, (Vorarlberg) In patients with underlying heart disease causing degeneration of the conduction pathway, a tachycardia dependent bundle branch block can occur. Idiopathic fibrosis and calcification of the conduction system, called Lenegre’s disease or Lev’s disease, is a less common cause of right bundle branch block but most commonly occurs in the elderly. RBBB can also be induced iatrogenically from right heart catheterizations and by ethanol ablation for a septal reduction in hypertrophic cardiomyopathy. Increased right intraventricular pressure, either acutely by pulmonary embolism or chronically as in cor pulmonale, can stretch the right bundle branch causing a bundle branch block. Infections such as myocarditis or myocardial infarction can cause direct cellular damage to the right bundle branch. Rarely, hyperkalemia can alter the conduction physiology by slowing electrical impulse conduction through cardiac tissue, causing a right bundle branch block. Ī right bundle branch block is typically caused by disease processes that change the myocardium of the right bundle branch, for example, structural changes, trauma, and infiltrative processes. The terminal right bundle is injured during ventriculotomy or transatrial resection. The distal right bundle is typically only injured when the moderator band is transected during surgery. The proximal right bundle nearest the endocardium is the most common location to be affected. ĭue to the anatomy of the right bundle branch, damage typically occurs at 3 different locations. In asymptomatic patients, isolated right bundle branch block typically does not need further evaluation. Although there is no significant association with cardiovascular risk factors, the presence of a right bundle branch block is a predictor of mortality in myocardial infarction, heart failure, and certain heart blocks. It can also occur iatrogenically from certain common cardiac procedures, such as right heart catheterization. Right bundle branch block is associated with structural changes from stretch or ischemia to the myocardium. It also receives collateral circulation from the right or left circumflex coronary arteries, depending on the dominance of the heart. The right bundle branch receives most of its blood supply from the anterior descending coronary artery. It then dives deeper into the muscular layer before re-emerging near the endocardium again. Initially, the right bundle branch off of the bundle of His travels down the interventricular septum near the endocardium. The bundle of His divides in the interventricular septum into the right and left bundle branches. Right bundle branch block (RBBB) is an electrocardiogram finding that occurs when the physiologic electrical conduction system of the heart, specifically in the His-Purkinje system, is altered or interrupted resulting in a widened QRS and electrocardiographic vector changes.
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