Cardiology Flashcards
ECG leads and relevant blood supply
II, III, aVF - Right coronary artery
I, aVL, V5 + V6 - Left circumflex artery
V2-V4 - Left anterior descending artery
V2-V6 - Left main stem
V1, V2, V3 (posterior view) - RCA
How to calculate rate on an ecg
300 / number of large squares between two equivalent adjacent points
Rhythm in AF
No discernible P waves
Irregularly Irregular
Rhythm in Atrial flutter
Saw-toothed baseline
Rhythm in nodal/junctional rhythm
Regular QRS but no P waves
Normal axis deviation
Leads I and II +ve
Left axis deviation
Lead I +ve and lead II -ve (leaving)
Right axis deviation
Lead I -ve and lead II +ve (reaching)
Causes of right axis deviation
- Anterolateral MI
- RVH
- PE
- Left posterior hemiblock WPW
- Atrial Septal Defect secundum
Causes of left axis deviation
- Inferior MI
- LVH
- Left anterior hemiblock WPW
- Atrial septal defect primum
Causes of absent P waves
AF
Sinoatrial node block
Nodal rhythm
Cause of dissociated P waves
Complete heart block
P mitrale
bifid P waves = Left Atrial hypertrophy
HTN, AS, MR, MS
https://ecgwaves.com/the-ecg-in-left-and-right-atrial-enlargement-abnormality-p-pulmonale-p-mitrale/
P pulmonale
peaked p waves = Right Atrial hypertrophy
Pulmonary HTN, COPD
https://ecgwaves.com/the-ecg-in-left-and-right-atrial-enlargement-abnormality-p-pulmonale-p-mitrale/
Definition and causes of wide QRS
> 120ms (3 small squares)
Ventricular initiation
Conduction defect
WPW
Definition and cause of pathological Q wave
> 1mm wide and >2mm deep
Full thickness MI
Signs of RVH in the QRS complexes
Dominant r wave in V1 + deep S wave in V6
Signs of LVH in the QRS complexes
R wave in V6 >25mm
R wave in V5/V6 + S wave in V1 >35mm
Length of normal PR interval
120-200ms (3-5 small square)
Cause of long PR interval
Heart block
Causes of short PR interval
- Accessory conduction eg WPW
- Nodal rhythm
- Hypertrophic Cardiomyopathy
Cause of depressed PR segment
Pericarditis
Normal corrected QT interval (QTc)
380-420ms
Bazett’s formula
Used to calculate corrected QT interval
QTc = actual QT/√R-R
Causes of long QT interval (>420ms)
TIIMME
Toxins
- macrolides
- anti-arrhythmics: quinidine, amiodorone
- TCAs
- Histamine antagonists
Inherited eg Romano-Ward, Jervell Lange-Neilson syndrome
Ischaemia
Myocarditis
Mitral valve prolapse
Electrolytes
- ↓Mg, ↓K, ↓Ca, ↓ temp
Causes of short QT interval (<380ms)
Digoxin
Betablockers
Phenytoin
Causes of raised ST segment (>1mm in limbs; >2mm in chest)
Acute MI
Prinzmetal’s variant angina
Pericarditis - saddle-shaped
Aneurysm - ventricular
Causes of depressed ST segments (>0.5mm)
Ischaemia - flat
Digoxin - down-sloping
T waves are normally inverted in which leads
aVR and V1
Also V2-V3 less so and more commonly in Afro-Caribbeans
Leads in which inverted T waves is abnormal and causes
I, II and V4-6
- Strain
- Ischaemia
- Ventricular hypertrophy
- BBB
- Digoxin
Effect of hyperkalaemia and hypokalaemia on T waves
Hyperkalaemia - tented T waves
Hypokalaemia - flattened T waves
U waves on ECG
Occur after T waves
Seen in hypokalaemia
J waves / Osbourne waves on ECG
Occur between QRS and ST segment
Causes
- Hypothermia < 32
- Subarachnoid haemorrhage
- Hypercalcaemia
Causes of bradycardia
DIVISIONS
- Drugs
- Ischaemia/infarction
- Vagal hypertonia
- Infection
- Sick sinus syndrome
- Infiltration
- HypO-thyroidism / kalaemia / thermia
- Neuro: ↑ ICP
- Septal defect: primum ASD
- Surgery or catherisation
Drugs which cause bradycardia
Antiarrythmics (type 1a, amiodarone)
Beta-blockers
Calcium channel blockers
Digoxin
Infections which cause bradycardia
Viral myocarditis
Rheumatic fever
Infective endocarditis
Infiltrative causes of bradycardia
Autoimmune Sarcoid Haemochromatosis Amyloid Muscular dystrophy
Definition of Narrow Complex Tachycardia
Rate >100bmp
QRS width <120ms
Management of SVT
see AS medicine notes, page 13
Definition of Broad Complex Tachycardias (VT)
Rate >100bmp
QRS width >120ms
Causes of VT
IM QVICK
- Infarction
- Myocarditis
- QT interval increase
- Valve abnormality - mitral prolapse, AS
- Iatrogenic - digoxin, antiarrythmics, catheter
- Cardiomegaly (esp. dilated)
- K↓, Mg↓, O2↓, acidosis
Management of VT
see AS medicine notes, page 14
Common causes of AF
IHD
Rheumatic heart disease
Thyrotoxicosis
Hypertension
Symptoms of AF
Asymptomatic Chest pain Palpitations Dyspnoea Faintness
Signs of AF
Irregualrly irregular pulse
Pulse deficit: difference between pulse and HS
Fast AF -> loss of diastolic filling -> no palpable pulse
Signs of LVF
CHA2-DS2-VAS Score components
- Congestive Heart Failure
- Hypertension
- Age≥75 (2 points)
- Diabetes
- Stroke or TIA (2 points)
- Vascular disease
- Age: 65-74yrs
- Sex: female
->Determines necessity of anticoagulation in AF
Score
0: aspirin 300mg
≥1: Warfarin
Management of Acute AF (≤48h)
Haemo unstable → emergency cardioversion
- electrical or pharmaceutical - 1st: Flecainide (if no structural heart disease) 2nd: Amiodarone
Control ventricular rate
- 1st line: diltiazem or verapamil or metoprolol
- 2nd line: digoxin or amiodarone
Start LMWH
Paroxysmal AF
- Self-limiting, <7d, recurs
- Anticoagulate: use CHADSVAS
- Rx “pill-in-pocket” : flecainide, propafenone
- Prevention: β-B, sotalol or amiodarone