Objectives: T wave normal abnormal ST elevation/ depression Diastolic current of injury Systolic current of injury Q waves normal abnormal T WAVE The Normal T wave Mechanism of a normal T wave Because the Purkinje fibers are located subendocardially, depolarization of the myocardium is endocardial to epicardial in direction. A surface electrode overlying the myocardium will record a tall QRS complex. Although the epicardium is the last to be depolarized, it is the earliest to recover because it has the shortest action potential duration when compared to other cells in the myocardium. Because the direction of repolarization is epicardial to endocardial, this causes the T wave to be normally uprigh. In general Frontal plane: T waves are inverted in aVR, and may be flat/inverted in III,aVL. The usual height is upto 5 mm but can be upto 8 mm Horizontal plane: T waves are inverted in V1, V2. The usual height is upto 10 mm but can be upto 12 mm FRONTAL PLANE In the frontal plane, the a...
Objectives: LVH RVH PE EKG of LVH Several EKG criteria have been used in the diagnosis of LVH. These include: CHANGES IN THE PRECORDIAL LEADS Abnormalities in the QRS complex Increased amplitude or voltage of the QRS complex Limb leads R wave in any limb lead measuring ≥20 mm S wave in any limb lead measuring ≥20 mm R wave in aVL >11 mm R in lead I +S in III >25 mm Precordial leads S wave in V1 or V2 ≥30 mm R wave in V5 or V6 ≥30 mm R wave in V5 or V6 >26 mm S wave in V1, V2 or V3 ≥25 mm R wave in V4, V5 or V6 ≥25 mm SV1 + RV5 or V6 > 35 mm Tallest S + tallest R in V1 to V6 >45 mm R wave in V6 > R wave in V5 Limb + Precordial leads R wave in aVL + S wave in V3 >20 mm in females R wave in aVL + S wave in V3 >28 mm in males Total QRS voltage from all 12 ECG leads >175 mm Increased duration of the QRS complex Delayed onset of intrinsicoid deflection ≥ 0.05 seconds in V5 or V6 Increased duration of the QRS complex ≥ 0.09 seconds Abnormalities in the ST segment...