ECG Flashcards
(11 cards)
Where do you measure the PR segment from and what can changes indicate?
From the end of the P wave to the start of the QRS. Elevation or depression here can indicate Pericarditis or Atrial Infarction.
What are the four causes of poor R wave progression (assuming ECG lead placement is correct)?
RVH, LVH, prior Anteroseptal MI, Dilated Cardiomyopathy.
What are the two causes of biphasic T waves and what pattern do they follow?
Ischaemia = up then down.
Hypokalaemia = down then up.
What method can you use to calculate HR from small squares?
1500/small squares between R-R = HR.
Describe the differences between LBBB and RBBB on an ECG.
LBBB - poor R wave progression, large R wave in V1. RBBB - RSR pattern in V1 - V3. Wide slurred S wave in lateral leads.
What are the rates of VF and how does it deteriorate?
150-500bpm. Amplitude decreases with duration and goes from coarse to fine VF.
What are the types of AVNRT, which are most common and what ECG traits do they show? Why can it cause polyuria?
Fast-slow AVNRT = antegrade conduction down the fast pathway and retrograde up the slow. Retrograde P wave appears after QRS.
Slow-fast AVNRT = most common, antegrade slow conduction and retrograde fast conduction. Retrograde P wave appears embedded in the QRS or just after it like a pseudo r’ or S wave.
Slow-slow AVNRT (atypical AVNRT) = Rare. Uses antegrade slow pathway conduction and slow left atrial fibres approaching the AV node for retrograde conduction. Increased atrial pressure can cause polyuria.
What is AVRT, what are the types and what ECG features do they have?
Re-entry circuit formed of accessory pathway and the AV node.
Orthodromic: Antegrade conduction via AV node so QRS duration <120ms.
Antidromic: Retrograde conduction via AV node so QRS duration >120ms.
What are the atrial rates of fibrillation and flutter?
Flutter ~300bpm. Fibrillation 400-600bpm.
How many seconds must pass to constitute a sinus arrest?
Minimum 3.
What are the criteria for RAE and LAE?
LAE: Biphid P wave in II (P mitrale), negative terminal portion enlarged in V1.
RAE: P wave amp >2.5mm in inferior leads, >1.5mm in V1 and V2.
