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CLINICAL SKILLS - PART 9

Tôi QRS phức điểm với nhau như chữ R III chì IS = R có nghĩa 90 ° II Dẫn tôi S R có nghĩa 90 ° III QRS phức tạp - Bình thường nếu chiều rộng 0,12 thứ hai - khối chi nhánh bó. - Một QRS dường như rộng phức tạp, | Electrophysiology of Cardiac Contractions 251 Normal if width 0.12 second three small squares . If 0.12 second bundle-branch block. An apparently wide QRS complex 0.12 second wide partial bundle-branch block or interventricular conduction defect. Left bundle-branch block LBBB is usually associated with some form of heart disease. RBBB is often a normal variation especially in athletes. Immediately after a myocardial infarction the development of RBBB may be serious. Left bundle-branch block M pattern in V6. Throughout ECG slurred ST segment and T wave inversion opposite to major deflection of QRS. LeadV6 depolarization of septal muscle from right bundle gives positive deflection 252 Chapter 12 The 12-Lead Electrocardiogram right heart depolarization gives negative deflection left heart depolarization gives positive deflection V6 J Standard leads left axis deviation as impulse spreads from right bundle up to left ventricle also occurs if only anterior fascicle of left bundle blocked left anterior hemiblock Right bundle-branch block M pattern in V1. LeadV1 depolarization of septal muscle from left bundle gives positive deflection left heart depolarization gives negative deflection right heart depolarization gives positive deflection Electrophysiology of Cardiac Contractions 253 Lead V V1 -A Ak r- V xr 1 V 1 V 1 V 1 V Standard leads axis usually normal as depends on large muscle mass of left ventricle if RBBB is associated with left axis there is block of anterior fascicle of left bundle bifascicular block All heart is being excited via remaining posterior fascicle of left bundle. Arrhythmias sinus arrhythmia ectopics tachycardias bradycardias Sinus arrhythmia Normal variation with respiratory rate increase rate on .