Arrhthymias Flashcards
What are ectopic beats?
Beats or rhythms that originate in places other than the SA node
Are ectopic beats always dangerous?
No, depends on how they affect cardiac output
Can myocarditis cause an arrhythmia?
Yes
What is the congenital long QT syndrome a mutation of?
mutation of cardiac ion channels (can cause arrhythmias)
What causes WFW syndrome?
presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles
What do local areas of ischemia or necrosis do to automaticity of neighboring cells?
increase
What is triggered activity thought to be the underlying mechanism for?
digoxin toxicity, Torsades de Pointes in the long QT syndrome and hypokalaemia
What does a stress ECG look for?
Looks for myocardial ischaemia, exercise related arrhythmias
What are q waves a sign of?
previous MI
What is pre-excitation a sign of?
WPW syndrome
What does an echo help find?
structural heart disease (e.g enlarged atria in AF, LV dilatation, previous MI scar, aneurysm)
There is generally no treatment for Atrial Ectopic Beats, but what may help?
avoiding stimulants, B-blockers
What type of MI is ischaemia commoner in?
STEMI
What is the treatment for sinus bradycardia?
Atropine (acute cases)
Pacing if haemodynamic compromise: hypotension, CHF, angina, collapse
What is the treatment for sinus tachycardia?
Treat underlying cause
B-blockers
What may SVTs be due to?
AV nodal re-entrant tachycardia
Accessory pathway tachycardia i.e., Wolff Parkinson White syndrome
Ectopic atrial tachycardia
What is the acute management for an SVT?
Vagal manoeuvres, carotid massage
IV Adenosine
IV Verapamil
What is the chronic management for an SVT?
Avoid stimulants Radiofrequency ablation Antiarrhythmic drugs (Class II or IV)
What does this describe: Selective cautery of cardiac tissue to prevent tachycardia, targeting either an automatic focus or part of a re-entry circuit?
Ablation
In ablation, catheters are placed in the heart via what vein?
femoral
What does ablation involve?
Intracardiac ECG recorded during sinus rhythm, tachycardia and during pacing manoeuvres
Catheter placed over focus / pathway and tip heated to 55-65C
What does an intracardiac ECG show?
shows the activation sequence of the heart
Which is more detailed, an intracardiac ECG or an ECG?
intracardiac ECG
What drugs can cause AVN conduction disease?
B-blockers
Calcium channel blockers
What disease may these genetic conditions cause: Lenegre’s disease, myotonic dystrophy?
AVN conduction disease
What happens to the PR interval in first degree heart block?
P-R interval longer than normal (> 0.2 sec)
What is the treatment for 1st degree heart block?
None (but follow up recommended)
What is 2nd degree heart block?
Intermittent block at the AVN (dropped beats)
What happens in Mobitz 1?
progressive lengthening of the PR interval, eventually resulting in a dropped beat
What happens in Mobitz 2?
Intermittent non-conducted P waves without progressive prolongation of the PR interval
Where is Mobitz type 2 almost always located?
bundle branches
Why would a transcutaneous pacer be used?
emergency temporary use till venous access achieved
Is transcutaneous pacing painful?
Yes
What vein should be used if patient had received streptokinase and is at risk of major bleed if the artery is punctured accidentally?
femoral
What does a single chamber pacemaker pace?
the right atria or right ventricle only
What does a dual chamber pacemaker pace?
the RA and RV
What is a dual chamber pacemaker used for?
AVN disease
What are atrial pacemakers used in?
isolated Sino-atral node disease but normal AV node
What type of pacemaker would be used in AF with a slow ventricular rate?
ventricular single pacemaker
Are Premature Ventricular Ectopics common?
yes
What may premature ventricular ectopics be a marker for?
inherited arrhythmia syndromes e.g. cardiomyopathy
When would you need to investigate a Premature Ventricular Ectopic beat further?
if it worsens on exercise
What is used to treat Premature Ventricular Ectopics?
beta blockers
Who are VTs common in?
patients with significant heart disease e.g.
Coronary artery disease
A previous myocardial infarction
What is a familial arrhythmial syndrom which can cause VT?
Long QT, Brugada syndrome
Can cardiomyopathy cause VT?
yes (a rare cause)
What does this describe: Chaotic ventricular electrical activity which causes the heart to lose the ability to function as a pump?
ventricular fibrillation
What is the treatment for VF?
Defibrillation, Cardiopulmonary resuscitation
What is the acute treatment for VT?
DC cardioversion if unstable
If stable: consider pharmacologic cardioversion with AAD
If unsure if VT or something else - adenosine
What changes in electrolyte balance could cause VT?
Hypokalaemia, hypomagnesaemia
What medications could cause VT?
that prolong the QT interval i.e. sotalol, quinidine, terfenadine, erythromycin
How could you correct ischaemia in VT?
revascularisation
Should anti-arrhythmic drugs be used for long term VT?
No
What should be used for life threatening long term VT?
Implantable cardiovertor defbrillators (ICD)
What types of AF are there?
paroxysmal, persistent or permanent
What is the common sustained arrhythmia?
AF
How long does paroxysymal AF last?
less than 48 hours
What is permanent AF?
cannot restore NSR by any method
Can persistent AF be carioverted to NSR?
Yes
Is Sick sinus syndrome ‘tachy brady syndrome’ related to AF?
Yes
Can idiopathic AF be genetic?
Yes
What are the symptoms of AF?
Chest pain Dyspnea Sweatiness Fatigue Palpitations Pre-syncope (dizziness) Syncope
In AF what is there an ectopic focus around?
pulmonary veins
What is the atrial rate in AF?
> 300bpm
What can be seen on an ECG in AF?
Irregularly irregular pulse
Absence of P waves
Presence of ‘f’ waves
Can AF exist with a slow ventricular rate?
Yes
What happens to cardiac output in AF?
decreased
Which rate control drugs should be used in AF?
Betablockers
Verapamil, diltiazem
Digoxin (not first line)
How can rhythm be controlled in AF (to restore NSR)?
- Pharmacologic cardioversion (anti-arrhythmic drugs e.g. amiodarone)
- Direct Current Cardioversion (DCCV)
How can NSR be maintained in AF?
Anti-arrhythmic drugs
Catheter ablation of atrial focus/ pulmonary veins
Surgery (Maze procedure)
What class of anti-arrhythmic drugs are sodium channel blockers?
1
What class of anti-arrhythmic drugs are beta-blockers?
2
What class of anti-arrhythmic drugs are potassium channel blockers?
3
What class of anti-arrhythmic drugs are calcium channel blockers?
4
What action potential phase is blocked in each of the anti-arrhythmic drug classes?
Class 1 - 0
Class 2 - 4
Class 3- 3
Class 4 - 2
Which anti-arrhythmic drug classes are rate control and which are rhythm control?
Rate - 2,4
Rhythm - 1,3
Which anti-arrhythmic drug class prolongs action potentials?
3
What are examples of class 3 anti-arrhythmic drugs?
Amiodarone, sotalol, dronedarone
What do Torsades de Pointes have a rate of?
200 - 250 bpm
How do Torsades de Pointes appear on an ECG?
Long QT interval
Wide QRS
Continuously changing QRS morphology
Irregular rhythm
What events can cause TdP?
Hypokalemia Prolongation of the action potential duration (drug induced) Renal impairment (increased drug levels)
Does Thyrotoxicosis put you at risk of thromboembolism?
Yes
Which valve diseases are an indication for thromboembolism?
MS and MR
Why would radiofrequency ablation be used in AF?
To maintain SR
by ablating AF focus (usually in the pulmonary veins)
For rate control
Ablation of the AVN to stop fast conduction to the ventricles
Is atrial flutter usually paroxysmal?
Yes
What circuit is Atrial Flutter sustained by?
macro-reentrant
In atrial flutter, where is the circuit confined to?
Circuit is confined to the right atrium
What does atrial flutter usually progress to?
AF
Is radiofrequency ablation successful in Atrial flutter?
Yes
What should drug treatment for Atrial flutter aim to do?
Slow the ventricular rate
Restore sinus rhythm
Maintain sinus rhythm once converted
