ecg basics for physiotherapy students reference purpose

ECG basic easy understanding

1. ECG INTERPRETATION

2. TOPICS BASICS- conduction system, waves, intervals, axis. MI Cardiac Enlargements Arrythmias Conduction defects

3. Conduction system

4. Recording

5. Calibration Why use 50 mm/second? Doubling the standard rate can reveal subtle ECG findings hidden at the slower rates, in particular atrial flutter waves in a 2:1 block:

6. Leads

7. Sequence of interpretation: Rate R hythm . A xis P wave , PR interval . QRS complex . ST-segment T wave, QT interval

8. RATE:

9. RHYTHM R hythm strip. On a 12 lead ECG this is usually a 10 second recording from Lead II. Sinus rhythm: p upright in lead 2 p inverted in avR Each p wave is similiar . Pattern of QRS comple xes-reg/irreg QRS morphology: Narrow complex: sinus, atrial or junctional origin. Wide complex: ventricular origin, or supraventricular with aberrant conduction. P waves: Absent: sinus arrest, atrial fibrillation Present: morphology and PR interval may suggest sinus, atrial, junctional or even retrograde from the ventricles. Relationship between P waves and QRS complexes: AV dissociation -For conduction blocks

10. (a) Normal Sinus Rhythm (b) Ventricular Fibrillation (c) Atrioventricular Block (d) Premature Ventricular Contraction (e) Atrial Flutter (f) Atrial Fibrillation.

11. Axis:

12. Waves and Intervals:

13. P- wave A trial depolarisation Duration: < 0.12 s ( 3 small squares) Amplitude : < 2.5 mm (0.25mV) in the limb leads < 1.5 mm (0.15mV) in the precordial leads Atrial abnormalities - most seen in the inferior leads (II, III and aVF) and lead V1 . P mitrale (bifid P waves), seen with left atrial enlargement. P pulmonale (peaked P waves), seen with right atrial enlargement. P wave inversion, seen with ectopic atrial and junctional rhythms. Variable P wave morphology, seen in multifocal atrial rhythms.

14. PR INTERVAL: PR interval - 120 – 200 ms (0.12-0.20s) in duration (three to five small squares). PR interval is > 200 ms, first degree heart block is said to be present. PR interval < 120 ms suggests P re-excitation (the presence of an accessory pathway between the atria and ventricles) or AV nodal (junctional) rhythm.

15. QRS Complex:

16. Narrow QRS Complex Morphology Narrow (supraventricular) complexes ) 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) Broad/Wide QRS Complexes A QRS duration > 100 ms is abnormal A QRS duration > 120 ms is required for the diagnosis of bundle branch block or ventricular rhythm Causes: Bundle branch block (RBBB or LBBB) Hyperkalaemia Poisoning with sodium-channel blocking agents (e.g. tricyclic antidepressants) Pre-excitation (i.e. Wolff-Parkinson-White syndrome) Ventricular pacing Hypothermia

17. Qwave Pathological if - > 40 ms (1 mm) wide > 2 mm deep > 25% of depth of QRS complex Seen in leads V1-3 Myocardial infarction Cardiomyopathies — Hypertrophic (HCM), infiltrative myocardial disease

18. ST segment:

19. Primary st t changes abnormal repolarisation ischemia electrolyte disorders drug side effects. Secondary st t changes abnormal depolarisation causes abnormal repolarisation. bbb vent.hypertrophy premat. vpc pacemaker beats.

20. T WAVE

21. TO BE CONTINUEDDD.....