ECG causes Flashcards
Causes
1
Q
Causes
Myocardial ischaemia ECG features
A
- A prolonged PR interval
- A long QT interval
- Right bundle branch block
- Right axis deviation
- Peaked T waves
- Inverted T waves
- Left bundle branch block
- ST depression
- ST elevation
2
Q
Causes
Causes of ST-segment elevation
A
- STEMI
- LV aneurysm
- Takotsubo (stress) cardiomyopathy
- Coronary vasospasm (Prinzmetal angina)
- Acute stroke
- Early repolarisation
- Pericarditis (saddle shaped)
- During angioplasty
- Non-standard ECG acquisition settings (eg on monitor)
- Normal variant - ‘high take-off’
- Subarachnoid haemorrhage
3
Q
Causes
Lengthens QT interval
A
Congenital:
- Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel),
- Romano-Ward syndrome (no deafness)
Drugs:
- amiodarone,
- sotalol,
- class 1a antiarrhythmic drugs,
- tricyclic antidepressants,
- selective serotonin reuptake inhibitors (especially citalopram),
- methadone,
- chloroquine,
- erythromycin,
- haloperidol,
- ondansetron
Others:
- electrolyte disturbances (hypocalcaemia, hypokalaemia, hypomagnesaemia),
- acute myocardial infarction,
- myocarditis,
- hypothermia,
- subarachnoid haemorrhage
4
Q
Short QT interval
A
- Hypercalcaemia
- Digoxin toxicity
- Hyperkalemia
- Hyperthermia
- Acidosis
- Effect of catecholamine
- Activation of ATP-sensitive potassium current
- Activation of acetylcholine-sensitive potassium current
- Myocardial ischemia
- Increased vagal tone
5
Q
Prolonged PR interval
A
- Idiopathic
- Ischaemic heart disease
- Digoxin toxicity
- Hypokalaemia
- Rheumatic fever
- Aortic root pathology e.g. abscess secondary to endocarditis
- Lyme disease
- Sarcoidosis
- Myotonic dystrophy
Note: no hypocalcemia
Digoxin causes prolonged PR and short QT
6
Q
Short PR interval
A
- Wolff-Parkinson-White (WPW) syndrome
7
Q
Inverted T waves
A
- Myocardial ischaemia
- Digoxin toxicity
- Subarachnoid haemorrhage
- Arrhythmogenic right ventricular cardiomyopathy
- Pulmonary embolism (‘S1Q3T3’)
- Brugada syndrome
8
Q
Peaked T waves
A
- Hyperkalaemia
- Myocardial ischaemia
9
Q
Causes of ST depression
A
- Secondary to abnormal QRS (LVH, LBBB, RBBB)
- Ischaemia
- Digoxin
- Hypokalaemia
- Syndrome X
10
Q
Causes of LBBB
A
- Ischaemic heart disease
- Hypertension
- Aortic stenosis
- Cardiomyopathy
- Rare: idiopathic fibrosis, digoxin toxicity, hyperkalaemia
11
Q
Causes of RBBB
A
- Normal variant - more common with increasing age
- Right ventricular hypertrophy
- Chronically increased right ventricular pressure - e.g. cor pulmonale
- Pulmonary embolism
- Myocardial infarction
- Atrial septal defect (ostium secundum)
- Cardiomyopathy or myocarditis
- According to OE both primum & secundum cause RBBB
12
Q
Causes of left axis deviation (LAD)
A
- Left anterior hemiblock
- Left bundle branch block
- Wolff-Parkinson-White syndrome (right-sided accessory pathway)
- Hyperkalaemia
- Congenital: ostium primum ASD, tricuspid atresia
- Minor LAD in obese people
13
Q
Causes of right axis deviation (RAD)
A
- Right ventricular hypertrophy
- Left posterior hemiblock
- Chronic lung disease → cor pulmonale
- Pulmonary embolism
- Ostium secundum ASD
- Wolff-Parkinson-White syndrome (left-sided accessory pathway)
- Normal in infant < 1 years old
- Minor RAD in tall people
14
Q
Causes of RBBB + RAD
A
- Right ventricular hypertrophy
- Pulmonary embolism
- Cor pulmonale
- Ostium secundum ASD
15
Q
Causes of RBBB + LAD
A
- Ostium primum ASD
