Arrythmia And Atrial Fibrillation Flashcards
What is the normal length of the PR interval?
0.12 to 0.20 seconds
What is the normal length of the QRS complex?
0.08 to 0.12 seconds (3 squares)
What is the normal length of the QT interval?
0.35 to 0.43 seconds
What defines a narrow complex QRS?
Less than 0.1 m/s (less than 2.5 squares)
What defines a broad complex QRS?
Over 0.1 m/s (more than 2.5 squares)
What does a peaked P wave indicate?
Right atrial enlargement (P.pulmonale)
What does a bifid P wave indicate?
Left atrial enlargement
What is a Q wave?
A negative deflection before the R wave
When is a Q wave considered pathological?
If seen in V1-V3, indicates current or prior MI.
What does more than 3 different P wave shapes on rhythm strip indicate?
mutlifocal atrial rhythm
What does ST elevation indicate?
Ischaemic heart disease if downsloping in 2 leads
What are De Winter T waves?
Upsloping ST depression with symmetrical tall peaked T waves caused by occlusion of LAD.
What does ST elevation in anterior leads indicate?
LAD blockage
What does ST elevation in inferior leads typically indicate?
RCA blockage but can be PLV blockage
What is the blood supply to the lateral leads?
left circumflex artery
Wha is the blood supply to the inferior leads?
Right coronary artery, and sometimes PLV
What is the blood supply to the posterior region of the heart?
posterolateral artery, a branch of the left ventircle
What does ST elevation on mutiple leads in more than one orientation (anterior + inferior) indicate?
pericarditis with a saddle shape.
What is the effect of digoxin on the ECG?
Down-sloping P wave with flattened T waves, called a inverted tick, which indicates that it is working due to increasing contractility with increased myocardial oxygen demand.
What causes giant T waves inversions on chest leads?
Cerebral waves- due to raised ICP.
What is the effect of hypothermia on ECG?
Hypothermia causes a J/Osborn wave, that resembles a retrograde delta wave on the chest leads.
What does hyperkalemia cause on an ECG?
Tall, peaked T waves and bradycardia
->Hyperkalemia causes increased rate of repolarisation, reducing myocardial excitability which suppresses impulses from SA node causing tall tended/peaked T wave and bradycardia that can progress to cardiac
What is the effect of chronic hyperkalemia on the ECG?
In chronic hyperkalemia, there is a widening of the QRS in a bizarre shape sometimes, flattening of P wave , prolonged PR interval and conduction blocks.
It can progress to ventircular fibrillaiton
What is the effect of hypokalemia on ECG?
ECG changes occur with 2.5-2.9mmol/l causes reduced rate of repolarisation, with T wave inversion and ST depression on many leads. There is risk of progression t o life threatening ventricular arrythmias such as ventricular tachycardia, ventricular fibrillation and Torsades de pointes.
Hypokalemia is associated with hypomagnesaemia so treatment is with IV replacement of both