TY - CHAP M1 - Book, Section TI - Chamber Abnormalities and Intraventricular Conduction Defects A1 - Ferry, David R. Y1 - 2007 N1 - T2 - ECG in 10 Days, 2e AB - General statementsEchocardiography and other newer imaging techniques, not the electrocardiogram (ECG), are the gold standards for assessing chamber size and wall thickness.In general, the sensitivities of the following criteria are moderate (in the range of 50%), and the specificities are very high (> 90%).Right atrial abnormality (Day 2-1)The P wave is pointed in II, III, or aVF, and the amplitude is >2.5 mm (historically referred to as P pulmonale).P wave axis is frequently >70°.Left atrial (LA) abnormalityIn most forms of acquired LA abnormality, the commonest manifestation is a wide (>40 msec) and deep (>1 mm) terminal portion of the P wave in V1. (Day 2-2)An appearance typical in mitral valvular disease is a "double-humped" P wave, at least 130 msec in duration, in II, III, or aVF (so-called P mitrale). (Day 2-3)Biatrial abnormality—suggested by a combination of tall P waves in II, III, or aVF, and the terminal negativity in V1. (Day 2-4) DAY 2-01 DAY 2-02 DAY 2-03 DAY 2-04 Right ventricular hypertrophy (RVH) (Day 2-5)RVH is suggested by all the following:Right axis deviationA tall R wave in V1 (≥7 mm)R wave in V1 + S wave in V6 ≥10 mmR/S ratio in V1 ≥ 1Incomplete RBBB patternRight atrial abnormalityS > R in V6The diagnosis of RVH requires exclusion of the other causes of a tall R wave in V1 (see Day 9).RVH in patients with acquired pulmonary disease tends to present in a different form: (Day 2-6)Deep S waves are present across the precordium.The R wave transition across the precordium is delayed.Right axis deviation and right atrial abnormality are frequently present.Low voltage may be present.Left ventricular hypertrophy (LVH)Precordial leads (any of the following) (Day 2-7)S wave in V1 + R wave in V5 or V6 > 35 mm in adults (> 30 years)R wave in V5 or V6 > 26 mmLimb leads (any of the following) (Day 2-8)R wave in I > 14 mmR wave in aVL > 11 mmLVH is frequently accompanied by ST segment and T wave abnormalities, sometimes referred to as a "strain" pattern, but more appropriately as "repolarization" abnormalities.Low voltage (Day 2-9)DefinitionNo QRS complex with an absolute value ≥ 0.1 mv (10 mm)Or, no limb lead QRS ≥ 0.05 mv (5 mm) (so-called low voltage in the limb leads) DAY 2-05 DAY 2-06 DAY 2-07 DAY 2-08 DAY 2-09 CausesDecreased voltage production by the myocardiumRestrictive cardiomyopathies (amyloidosis, sarcoidosis, etc.)HypothyroidismIncreased impedance between the voltage producing source (the myocardium) and the ECG leadsFat (obesity)Air [chronic obstructive pulmonary disease (COPD), tension pneumothorax]Water (pericardial or pleural effusion, ascites)Intraventricular conduction defects (IVCDs)The concept of the intrinsicoid deflection time (IDT) delay The genesis of the normal QRS complex in V1 and I or V6Depolarization begins in the left side of the septum and proceeds initially rightward, resulting in a positive deflection in V1 and a small Q wave in I and V6.The bulk of the left ventricle is depolarized next to the left, producing a negative deflection in V1 and a tall R wave in I and V6.Depolarization of the right ventricle ... SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accesscardiology.mhmedical.com/content.aspx?aid=1128942049 ER -