TOPIC 4 Electrophysiology Topic Contents Normal 12-lead ECG 25 Lead position 25 Cardiac axis 25 Normal resting values 25 Abnormalities of the 12-lead ECG 27 Atrial hypertrophy 27 Left ventricular hypertrophy (LVH) 28 Right ventricular hypertrophy 28 Left bundle branch block 28 Right bundle branch block 28 Stress ECG 28 Bruce Protocol 28 Pathological changes during exercise 28 Signal averaged ECG 28 T wave alternans 29 Positive 29 Negative 29 Intermediate 29 Intracardiac electrograms 31 Typical 4-wire EP study 31 Catheter position 31 Normal activation pattern 33 Accessory pathways and Wolff-Parkinson-White syndrome 33 Pacemakers 33 Normal 12-lead ECG Lead position See Figure 4.1. Figure 4.1 Standard ECG lead position. (A) Standard limb lead position with corresponding electrocardiographic vectors. (B) Standard praecordial chest lead position. Cardiac axis See Figure 4.2. Normal axis: –30° to +90° Leftward axis: –30° to –90° Rightward axis: +90° to +180° Figure 4.2 Einthoven’s triangle demonstrating electrocardiographic vectors. Normal resting values Adult resting heart rate: 50–100 beats per minute ECG R-R interval (25 mm/s paper speed): each large square is 0.2 s; each small square is 0.04 s. P wave (best seen lead II) • Amplitude <2.5 mm. • Duration <12 ms. • Frontal plane axis 0 to +75°. PR interval: 120–220 ms QRS • Duration : <110 ms. • Normal q wave duration < 0.04 s, amplitude < 25% of R wave. • R waves begin in V1 or V2 and progress in size to V5 (R-V6 usually smaller than R-V5). • S waves begin in V6 or V5 and progress in size to V2 ( S-V1 usually smaller than S-V2). • Usual transition from S>R in the right precordial leads to R>S in the left precordial leads is V3 or V4. QT interval: • Male: < 440 ms • Female: < 460 ms • QT interval corrected for heart rate (QTc) = QT/√RR U wave • Amplitude < 1/3 T wave amplitude in the same lead. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: 10: Systemic vascular disease 9: Pulmonary vascular disorders 3: Preventative cardiology 5: Ventricular function Stay updated, free articles. Join our Telegram channel Join Tags: Cardiology Churchills Ready Reference Jun 5, 2016 | Posted by admin in CARDIOLOGY | Comments Off on 4: Electrophysiology Full access? Get Clinical Tree
TOPIC 4 Electrophysiology Topic Contents Normal 12-lead ECG 25 Lead position 25 Cardiac axis 25 Normal resting values 25 Abnormalities of the 12-lead ECG 27 Atrial hypertrophy 27 Left ventricular hypertrophy (LVH) 28 Right ventricular hypertrophy 28 Left bundle branch block 28 Right bundle branch block 28 Stress ECG 28 Bruce Protocol 28 Pathological changes during exercise 28 Signal averaged ECG 28 T wave alternans 29 Positive 29 Negative 29 Intermediate 29 Intracardiac electrograms 31 Typical 4-wire EP study 31 Catheter position 31 Normal activation pattern 33 Accessory pathways and Wolff-Parkinson-White syndrome 33 Pacemakers 33 Normal 12-lead ECG Lead position See Figure 4.1. Figure 4.1 Standard ECG lead position. (A) Standard limb lead position with corresponding electrocardiographic vectors. (B) Standard praecordial chest lead position. Cardiac axis See Figure 4.2. Normal axis: –30° to +90° Leftward axis: –30° to –90° Rightward axis: +90° to +180° Figure 4.2 Einthoven’s triangle demonstrating electrocardiographic vectors. Normal resting values Adult resting heart rate: 50–100 beats per minute ECG R-R interval (25 mm/s paper speed): each large square is 0.2 s; each small square is 0.04 s. P wave (best seen lead II) • Amplitude <2.5 mm. • Duration <12 ms. • Frontal plane axis 0 to +75°. PR interval: 120–220 ms QRS • Duration : <110 ms. • Normal q wave duration < 0.04 s, amplitude < 25% of R wave. • R waves begin in V1 or V2 and progress in size to V5 (R-V6 usually smaller than R-V5). • S waves begin in V6 or V5 and progress in size to V2 ( S-V1 usually smaller than S-V2). • Usual transition from S>R in the right precordial leads to R>S in the left precordial leads is V3 or V4. QT interval: • Male: < 440 ms • Female: < 460 ms • QT interval corrected for heart rate (QTc) = QT/√RR U wave • Amplitude < 1/3 T wave amplitude in the same lead. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: 10: Systemic vascular disease 9: Pulmonary vascular disorders 3: Preventative cardiology 5: Ventricular function Stay updated, free articles. Join our Telegram channel Join Tags: Cardiology Churchills Ready Reference Jun 5, 2016 | Posted by admin in CARDIOLOGY | Comments Off on 4: Electrophysiology Full access? Get Clinical Tree
