Heart block Flashcards
1st degree AV block
prolonged conduction through the AV node
2nd degree AV block mobitz type 1
Progressive prolongation of AV node conduction culminating in one atrial impulse failing to be conducted through the AV node
2nd degree AV block mobitz type 2
intermittent or regular failure of conduction through the AV node. Also defined by the number of normal conductions per failed one.
3rd degree AV block
No relationship between atrial and ventricular contraction. Failure of conduction though the AV node leads to ventricular contraction bya focus of depolarisation within the ventricle.
Heart block risk factors (6)?
MI or IHD, infection (rheumatic fever, infective endocarditis), drugs (digoxin), metabolic (hyperkalaemia), infiltration of conducting system
1st and 2nd degree heart block symptoms?
usually asyptomatic
Mobitz type 2 and complete heart block symptoms?
Stokes-Adams attacks (syncope caused by ventricular asystole), dizziness, chest pain, heart failure.
Heart block investigations bloods?
TFTs, Digoxin levels, cardiac enzymes, troponin
1st degree AV block ECG?
fixed prolonged PR interval >0.2s
Mobitz type 1 ECG?
progressively prolonged PR interval, culminating in a P wave that is not followed by a QRS complex
Mobitz type 2 ECG?
intermittently a P wave isn’t followed by a QRS
Complete heart block ECG?
no relationship between P and QRS complexes
Heart block investigations CXR?
cardiac enlargement, pulmonary oedema
Chronic heart block management?
permanent pacemaker in complete heart block, advanced mobitz type 1 and symptomatic mobitz type 2
Acute heart block management?
IV atropine, consider external pacemaker.
