ECG abnormalities Flashcards
What are the ECG features of RVH?
Diagnostic features: - RAD of >109 - dominant R wave in V1 (>7mm or R/S ratio >1) -dominant S wave in V5 or V6 -QRS < 120ms Supporting criteria -RAE - p pulmonale -RV strain ST dep/TWI V1-4, II, III, aVF - S1Q3T3 patter - Deep S waves in lateral leads (I, aVL, V5-6)
What are the causes of RVH?
Pulmonary hypertension Mitral stenosis PE Cor pulmonale Congenital heart disease e.g. TOF, pulm stenosis, Arrythmogenic RV cardiomyopathy
What are the ECG features of LVH?
Most common diagnostic criteria is the Sokolov-Lyon criteria
- S wave depth V1 and tallerst R wave height V5 or v^ > 35mm
Voltage criteria must be accompanied by non-voltage criteria to be considered LVH
- Increased R wave peak time in V5 or V6
- ST segment depression and TWI in left sided leads
- May also be LAE, LAD
What is LVH?
Hypertrophy of LV in response to pressure overlaod secondary to conditions such as AS and HTN
The thickened LV walls lead to prolonged depolarisation and prolonged repolarisation in the lateral leads
What are the causes of LVH?
HTN AS AR MR Coarctation of the aorta Hypertrophic cardiomyopathy
What is RBBB and its ECG features?
Activation of the RV is delayed as depolarisation has to spread across the septum from the LV
ECG - Broad QRS
RSR’ pattern in V1-3
Wide slurred S wave in the lateral leads (I, aVL, V5-6)
ST depression and TWI V1-3
Normal axis
What are the causes of RBBB?
RVH PE IHD Myocarditis Primary degenerative disease of the conducting system Congenital heart disease (e.g. ASD)
What is LBBB and its ECG features?
In LBBB the noral septal depolarisation is reversed (becomes right -to -left) as the impulse spreads 1st to the RV and then the LV
ECG:
- QRS > 120ms
- dominant S wave in V1
- broad monophasic R wave in lateral leads (I, aVL, V5-6)
- prolonged peak R wave in V5-6
-ST segs and T waves are discordant with the QRS vector
- poor R wave progression in chest leads
-LAD
Describe QRS morphology in LBBB
maybe rS or QS in V1
R wave may be M shaped or notched
What are the causes of LBBB?
Aortic stenosis IHD HTN Dilated cardiomyopathy Anterior MI Primary degenerative disease of the conducting system Hyperkalaemia Digoxin toxicity
What is trifascicular block?
Conducting disease in RBB, LAF and LPF
Can be incomplete or complete
What are the ECG features of incomplete trifascicular block?
Fixed block of 2 fascicles (i.e bifascicular block) with delayed conduction in the remaining (1st or 2nd AV block)
What are the ECG features of trifascicular block?
3rd degree AV block with features of bifascicular block
What are the causes of trifascicular block?
IHD HTN AS Anterior MI Primary degenerative disease of the conducting system Congenital heart disease Hyperkalaemia Digoxin toxicity
What is left posterior fascicle block and what are the ECG features?
Impulses are conducted to the LV via the left anterior fascicle which inserts into the upper, lateral wall of the LV along its endocardial surface
ECG - small R waves and deep S waves (rS) in I and aVL
Small Q waves and tall R waves in II, III and aVF
QRS normal duration or slightly prolonged
Prolonged R wave peak in aVF
Increased QRS voltage in limb leads
No evidence of RVH
Rarely occurs in isolation - more likely to be found in the context of bifascicular block
Describe the cardiac conducting system
AVN
Bundle of His
Splits into RBB and LBB
LBB divides into LAF and LPF
What is left anterior fascicular block (left ant hemiblock) and what are the ECG criteria?
Impulses are conducted to the LV via the left posterior fascicle which inserts into the infero-septal wall of the LV
LAD
Small Q waves with tall R waves (qR) in I and aVL
Small R and deep S waves (rS) in II, III, aVF
QRS normal duration or slightly prolonged
Prolonged R wave peak time in aVL
Increased QRS voltage in the limb leads
What is bifascicular block?
Combination of RBBB with either LAFB or LPFB
Conduction to the ventricles via the single remaining fascicle
ECG shows RBBB and LAD or RAD
RBBB and LAFB is more common
What causes bifascicular block?
IHD HTN Aortic stenosis Anterior MI Primary degenerative disease of the conducting system Congenital heart disease Hyperkalaemia
What is Brugada syndrome?
An ECG abnormality with a high incidence of sudden death in patients with a structurally normal heart
Diagnosis depends on characteristic ECG plus clinical criteria
Due to a defect in the cardiac sodium channel gene (sodium channelopathy)
ECG changes can be transient and unmasked by fever, ischaemia, drugs e.g. B-blockers, cocaine, ETOH, decreased temp, hypokalaemia
Type 1 - coved ST elevation > 2 mm in > 1 of V1-3 followed by a negative T wave
ECG must be associated with documented VT, fmhx of sudden cardiac death < 45, coved-type ECGs in family members, inducible VT, syncope or nocturnal agonal respiration
What are the causes of LAD?
LVH LBBB Inferior MI Ventricaular pacing WPW Left ant fascicular block horizontal heart - short, squat person
What are the causes of extreme axis deviation?
ventricular rhythms e.g. VT
hyperkalaemia
Severe RVH
What are the causes of RAD?
RVH Acute RV strain e.g. PE Lateral STEMI Chronic lung disease e.g. COPD Hyperkalaemia Sodium channel blockade e.g. TCA poisoning WPW Dextrocardia Normal paediatric ECG Left post fascicular block Vertically orientated heart - tall, thin pt
What is atrial tachycardia?
It’s a form of SVT, originating in the atria but outside the sinus node
Both a.flutter and multifocal AT are specific types
Usually due to a single ectopic focus
The underlying mechanism can involve re-entry, triggered activity or increased automaticity
What are the ECG features of atrial tachycardia?
paroxysmal or sustained atrial rate > 100 P wave abnormal At least 3 consec identical ectopic p waves isoelectric baseline p waves inverted in II, III, aVF
