Arrhythmias Flashcards
ECG features of left bundle branch block
Wide QRS, deep S wave in V1, broad notched R wave in V6
Features of left anterior fasicular block
Left axis deviation and Initial R wave in inferior leads
Features of Left posterior fasicular block
Right axis deviation and initial R wave in 1 and aVL and q wave in inferior leads
ECG features of right bundle branch block
Wide QRS, rSR in V1, deep S wave in V6
Explain difference between two types of AV junctional re-entrant tachycardias
AVNRT- AV node is dissociated into 2 pathways which can both conduct impulses
AVRT- caused by an accessory pathway between atria and ventricles which can set up a re-entrant circuit with the AV node
What is direction of conduction in most AVNRT tachycardias?
Antegrade via slow pathway, retrograde via fast pathway (slow-fast type = 80-90%)
Explain reason for delta wave in sinus rhythm?
Conduction occurs via both accessory and AV nodal pathways. Accessory pathway is fast to conduct so impulse gets rapidly to ventricle (short PR and slurred upstroke) but then activation of ventricles is slow due to not being through usual conducting system. By this time the conduction has occurred through the slower AV node and ventricles get activated quickly via His-Purkinjie system so you see a normal QRS (fusion beat)
What are the two patterns of AVRT?
Orthodromic - antegrade conduction via AV node and retrograde via accessory (narrow complex)
Antidromic - antegrade conduction via accessory pathway and retrograde via AV node (large wide complexes with delta wave)
What are the two types of WPW?
Type A - v1 is positive, left sided accessory pathway
Type B - V1 is negative
Differences between AVRNT and AVRT on ECG
Hard to tell, can look at p wave
In AVNRT the p wave immediately follows or I superimposed on the QRS because the circuit is short
In AVRT inverted p waves occur halfway between the QRS complexes usually superimposed on the T waves
Features of pre-excited AF
Irregular
Different QRS morphologies - wide delta waves, normal QRS
Axis stable
Can deteriorate into VT or VF (more likely if faster rate
Treatments for AV junctional re-entrant tachycardias
Vagal stimulation Adenosine Verapamil, flecainide, sotalol, disopyramide Pacing Cardioversion
Prevention = ablation (high success-90%)
Lifetime risk of AF
Increases with age, lifetime = 26%
Causes of AF
Heart disease - ischaemia, heart failure, surgery, pericarditis, valvular disease, hypertension
Extrinsic - hyperthyroid, alcohol, Obesity, sleep apnoea, extreme exercise, infection, PE
Genetic
What makes up CHA2DS2-VASc?
C - cardiac failure H - hypertension A - over 75 = 2 points D - diabetes S - previous stroke or TIA = 2 points V - vascular disease (MI, peripheral vascular disease, significant aortic plaque) A - between 65-74 S- female
Stroke risk in AF
In general 5% per year
Risk stratified
Score 2 = 2.2%, score 5 = 10%
Difference between rate and rhythm control in AF?
Rate control is non inferior to rhythm control as per AFFIRM and RACE trials
But most rhythm control pts didn’t maintain sinus rhythm and a secondary analysis showed sinus rhythm was associated with better outcomes