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)
What is SVT?
Supraventricular tachycardia
Originates above the ventricles - in atria or AVN
Abnormal electrical activity triggers abnormal rhythm (hear accelerates too quickly + doesn’t allow time for it to fill before contraction0
RFs of SVT
Age, heart disease, thyroid problems, drugs, anxiety, obstructive sleep apnoea
What is the most common SVT?
Who does it affect?
AVNRT (atrioventricular nodal re-entrant tachycardia)
YOUNG WOMEN
Mx of SVT
Vagal manouvre (1st line)
If ineffective, given ADENOSINE
Does adenosine have a long or short duration of action?
VERY SHORT!
Symptoms of SVT
Palpitations, dizziness + light-headedness
What is VT?
Abnormal electrical signals in the ventricles = heart beats fast + out of sync with atria
When is VT usually symptomatic?
When it lasts >30 seconds
Symptoms of VT
Dizziness, light-headedness, palpitations, chest pain, LOC
Sustained episodes of VT may lead to…
LOC + cardiac arrest
Biggest RF for VT
Pre-existing heart problem (e.g. post-MI)
What factors make VT a more likely diagnosis than SVT
Patient is >60
History of IHD
QRS >0.13
Capture/ fusion beats
ECG criteria for VT
Brugada criteria
What is toursades de pointes?
Rare polymorphic VT with QRS of increasing + decreasing magnitude
Causes of toursades de pointes?
Hypomagnesia, hypokalaemia, prolonget QT (e.g. in tricyclics OD)
Mx of VT:
If unstable
If stable
Unstable: DC x 3, followed by IV amiodarone
Stable: IV amiodarone
What else can be used to treat VT in haemodynamically stable
IV lidocaine
Pathophysiology of VF
Rapid, erratic heartbeats = hear abruptly stops beating
Cause of VF
Problem with the heart’s electrical impulses after a previous MI or something else causing scarring of the myocardium
Is there a pulse in VF?
NO!!
Management of VF
CPR + immediate defibrilation
What is the most common cause of sudden cardiac death?
VF
