It is the characteristic finding in arrhythmogenic

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It is the characteristic finding in arrhythmogenic right ventricular dysplasia 90 Epsilon Wave
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91 1. Epsilon wave 2. T inversion in v 1 to v3 3. Positive QRS in v1
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Normal QRS width is 70-100 ms (a duration of 110 ms is sometimes observed in healthy subjects). The QRS width is useful in determining the origin of each QRS complex (e.g. sinus, atrial, junctional or ventricular). QRS Complex Morphology 92
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Main Features to Consider:- Width of the complexes: Narrow versus broad. Voltage (height) of the complexes. 93
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Narrow complexes (QRS < 100 ms) are supraventricular in origin. Broad complexes (QRS > 100 ms) may be either ventricular in origin, or may be due to aberrant conduction of supraventricular complexes (e.g. due to bundle branch block, hyperkalaemia or sodium-channel blockade). Width of the complexes: Narrow versus broad. 94
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Narrow (supraventricular) complexes arise from three main places :- Sino-atrial node (= normal P wave ) Atria (= abnormal P wave / flutter wave / fibrillatory wave ) AV node / junction (= either no P wave or an abnormal P wave with a PR interval < 120 ms ) Narrow Complexes Sinus rhythm: Each narrow complex is preceded by a normal P wave. Atrial flutter: Narrow QRS complexes are associated with regular flutter waves. Junctional tachycardia: Narrow QRS complexes with no visible P waves. 95
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A QRS duration > 100 ms is abnormal A QRS duration > 120 ms is required for the diagnosis of bundle branch block or ventricular rhythm Broad Complexes Ventricular tachycardia: Broad QRS complexes with no visible P waves. 96
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Bundle branch block Hyperkalemia Poisoning with sodium-channel blocking agents (e.g. tricyclic antidepressants) Pre-excitation (i.e. Wolff-Parkinson-White syndrome) Ventricular pacing Hypothermia CONDITIONS – BROAD COMPLEXES 97
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The QRS is said to be low voltage when: The amplitudes of all the QRS complexes in the limb leads are < 5 mm; or The amplitudes of all the QRS complexes in the precordial leads are < 10 mm. Low Voltage 98
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Increased QRS voltage is often taken to infer the presence of left ventricular hypertrophy . There are multiple “voltage criteria ” for left ventricular hypertrophy. Probably the most commonly used are the Sokolov- Lyon criteria (S wave depth in V1 + tallest R wave height in V5-V6 > 35 mm). High Voltage 99
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This is when the QRS complexes alternate in height . The most important cause is massive pericardial effusion, in which the alternating QRS voltage is due to the heart swinging back and forth within a large fluid-filled pericardium. Electrical Alternans 100
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The QT interval is the time from the start of the Q wave to the end of the T wave. It represents the time taken for ventricular depolarisation and repolarisation.
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  • Winter '16
  • jean grey
  • Cardiac electrophysiology, QRS, Rate

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