ECG in 20 seconds. A/Prof Peter Kas

Transcription

1 ECG in 20 seconds A/Prof Peter Kas

2 THE SYSTEM Tachy/brady arrhythmias 6 Pacing Spikes Pericarditis WPW Prolonged QT Morphology Wellens, Brugada, K abnormalities AMPLITUDE Delta wave? ischaemia

3 Junctional Bradycardia! There is no atrial activity! The QRS is narrow this means that the ventricle is depolarised by the normal conduction pathway ie., They are SUPRAVENTRICULAR Complexes! The rhythm is a junctional rhythm that is generated via the AV node.! The AVN has intrinsic automaticity to initiate impulses.! These are at a rate of 40-60bpm! There may/may not be retrograde P waves

4 AVN BLOCKS

5 1 st degree block! AV node block where PR > 0.2s ( )! There is prolongation of AV Conduction time! 1 st degree block and normal QRS has no adverse prognosis.

6 2 nd Degree Block! It occurs when one or more, but not every atrial impulse fails to reach the ventricles.! It may be intermittent or continuous! It can have any ratio of P waves to QRS s.! Think of it when you see a clumping of waveforms.! In one form of 2 nd degree block the PR prolongs until the QRS is dropped.

7 Mobitz 1 - Wenckebach! The AV node conducts every successive impulse earlier and earlier so the RR distance decreases.! At one point the impulse arrives when the AV node cannot conduct and so have a missed impulse.! The next impulse conducts and so it begins again.

8 Mobitz I - Wenckebach! PR interval prolongs! After missed beat PR is the shortest! RR shortens with every beat! pp interval stays the same

9 Mobitz II- 2 nd degree AVN block! PR stays the same! There are alternate conducted and nonconducted beats.! May degenerate to 3 rd degree heart block

10 3 rd degree No atrial Impulses are conducted to the Ventricles There is an escape or junctional rhythm that is regular. If no compensatory escape rhythm, there is arrest. 3 rd degree AV block always produces AV dissociation

11 Causes of WCT 1. VT 2. SVT with Aberrancy Arrhythmia Kalaemia Toxaemia 3. BBB 4. Torsades 5. Paced Rhythm 6. Na Channel Blockers- including TCA 7. Other OD s- Digoxin, Lithium, Cocaine 8. Hyperkalaemia

12 Diagnosing VT

13 How to diagnose VT 1. What is the patient s age- older= more chance of ischaemia 2. Are the complexes wide? >4 small squares (>160ms) 3. Are there p waves and s there AV dissociation? 4. Are there Capture beats or fusion beats 5. Is axis extreme? 6. Is there concordance in V1-V6 7. Is there RSr pattern? 8. Are the signs present 1. Brugada s Sign- QRS to S wave > 100ms 2. Josephson s Sign-Notching in the S wave

14 Capture beats in VT! Capture beats are narrow QRS complexes that occur earlier than expected. They show that the conduction system can depolarise the ventricles via normal conduction system.! They confirm VT

15 Fusion beats! They occur when a beat conducted via the AV node fuses with a beat arising from the ventricles.! It results in an intermediate looking beat and supports the diagnosis of VT

16 Capture Beat

17 How to diagnose VT 1. What is the patient s age- older= more chance of ischaemia 2. Are the complexes wide? >4 small squares (>160ms) 3. Are there p waves and is there AV dissociation? 4. Are there Capture beats or fusion beats 5. Is axis extreme? 6. Is there concordance in V1-V6 7. Is there RSR pattern? tall left ear in V1- very specific for VT 8. Are the signs present 1. Brugada s Sign- QRS to S wave > 100ms 2. Josephson s Sign-Notching in the S wave

18 Tall Rsr in V1

19 How to diagnose VT 1. What is the patient s age- older= more chance of ischaemia 2. Are the complexes wide? >4 small squares (>160ms) 3. Are there p waves and is there AV dissociation? 4. Are there Capture beats or fusion beats 5. Is axis extreme? 6. Is there concordance in V1-V6 7. Is there RSr pattern? 8. Are the signs present 1. Brugada s Sign- QRS to S wave > 100ms 2. Josephson s Sign-Notching in the S wave 100ms 2.5 sm sq

20 LVH! Lat leads! Tall R wave! Down-sloping ST segment! Assymetrical T wave! High voltage criteria! S(V1 or V2) + R (V5 or V6) >35mm! S in V1 + R in V5/6 > 35mm! Any R wave >20mm in limb or >25mm in praecordial

21 14mm" 23mm

22 Causes of low voltage! Pericardial Effusion! Pleural Effusion! Obesity! COPD! End stage Cardiomyopathy

23 Definition of Low Voltage! QRS in I + II + III < 15mm OR! QRS in V1 + V2 + V3 < 30mm

24 Electrical alternans (QRS) Causes include repolarisation(ami, long QT, HCM) conduction(mi, AF, WPW) and cardiac motion(effusion, HCM)

25 ST Elevation - causes! Acute AMI! Benign early Repolarisation! Pericarditis! LV aneurysm! Vasospasm! Bundle Branch Block

26 MI in LBBB Remember in LBBB Wide QRS Monophasic R wave in lateral leads -no Q or S waves Appropriate Discordance

27 Sgarbossa Criteria! Sgarbossa et al. have developed a clinical prediction rule to assist in the ECG diagnosis of AMI in the setting of LBBB using three specific ECG findings! Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundlebranch block. N Engl J Med 1996; 334:481-7.

28 DISCORDANCE! DISCORDANCE! When QRS points in one direction, the J-point is isoelectric or in the opposite direction! This is normal (in all 12 leads) except if the ST segment is > 5mm in opposite direction Discordant ST- elevation > 5mm Or >.25 QRS

29 CONCORDANCE! If the QRS and the j-point are in the same direction.! If ST elevation > 1mm = ischaemia.! Concordant ST-elevation > 1mm

30 CONCORDANCE! If ST depression in V1-V3 = ischaemia. Concordant ST-depression >1mm V1,V2 or V3

31 Sgarbossa Criteria ST Elevation 1 mm and concordant with QRS complex ST Depression 1 mm in V1, V2, V3 ST Elevation 5 mm and discordant with QRS complex Score 5 points Odds Ratio (OR) 25.2 Score 3 points OR 6.0 Score 2 points OR 4.3 Odds Ratio: a measure of the degree of association; for example, the odds of exposure among the cases compared with the odds of exposure among the controls (

32 Sgarbossa Criteria! A total score of 3 or more suggests that the patient is likely experiencing an AMI based on the ECG crtieria! With a score less than 3, the ECG diagnosis is less certain requiring additional evaluation! Chan TC, Brady WJ, Harrigan RA et al. ECG in Emergency Medicine and Acute Care. 1st ed. Pennsylvania: Elsevier Mosby; 2005.

33 PERICARDITIS ST elevation Concave upwards AMI Convex upwards ST elevation <5mm Diffuse ST changes No Q waves PR depression T wave inverts after ST normalises Mild reciprocal depression avr and V1 >5mm Confined changes Q waves No PR depression T wave changes concurrent with ST segment Deep changes opposite to ST elevation

34 Prolonged PR! > 0.2 sec or 1 large square! On its own means nothing! Although there are indications that it is associated with an increased risk of developing atrial fibrillation! May be associated with electrolyte abnormalities or medications such as beta or calcium channel blockers

35 QT! Beginning of QRS to end of T wave! = activation and recovery of ventricular myocardium! QTc = QT/sq root of RR! >0.44 seconds concerning! Causes! Inherited Lange-Neilsen (AR), Romano-Ward(AD)! Acquired! Drugs amiodarone, sotalol, haloperidol, methadone! Other Hypothyroidism, Hypercalcaemia