Palpitations Flashcards
What is complete heart block?
Complete dissociation of the atria + ventricles, so no conduction through the AVN
How may someone with complete heart block present?
Syncope
Hypotension
CV collapse
Sudden cardiac death
Others: fatigue, dizziness, reduced exercise tolerance, chest pain
In complete heart block, where do ventricular escape mechanisms occur?
Anywhere from the AVN to bundle branches
Which patients are less likely to be symptomatic?
Those with narrow complex escape rhythms (e.g. occurring above the bundle of His)
Two most common causes of complete heart block
Ischaemia or infarct
Drugs
Pathology: infiltration/ fibrosis
Metabolic causes of complete heart block
Hyperkalaemia
Hypothyroidism
Drugs causing complete heart block
Excess digoxin
Combination of beta blockers + CCB
ECG in complete heart block
Regular P-P
No relationship between P waves + QRS (more P waves than QRS)
Mx of acute complete heart block
ABCDE!
What drug is 1st line in acute complete heart block?
Dose/ Route/ Max dose
Atropine (500mcg IV)
Can repeat dose <3mg
What drug can be used as a temporary measure in acute complete heart block?
Adrenaline
Definitive Mx of complete heart block
Cardiac pacing
Difference between ICD + pacemaker
Pacemaker: helps control abnormal rhythms. Uses electrical impulses to prompt heart beat. Can speed up slow HR or control a fast HR etc
ICD: monitors heart rhythm. If it senses a dangerous rhythm a shock is delivered. ICD = PACEMAKER + DEFIBRILATOR
What is first degree heart block?
Prolonged PR
Second degree heart block:
Mobitz I
Mobitz II
Mobitz I: PR becomes longer + longer until a QRS is dropped (Wenckebach phenomenon)
Mobitz II: QRS is regularly missed (e.g 2:1 block)