Arrhythmias Flashcards by Rachel Hughes

How do you calculate HR from the rhythm strip of an ECG?

Calculate how many big boxes are between each QRS complex, then divide 300 by this number to get the rate

e.g. 4 boxes, 300/4=75bpm

How well did you know this?

Not at all

Perfectly

What are some symptoms and complications of arrhythmias?

Sudden death
Syncope
Chest pain
Fatigue
Dizziness
Palpitations
Embolisms

How well did you know this?

Not at all

Perfectly

How do you investigate possible arrhythmias?

12 lead 24hr ambulatory ECG monitoring
Blood tests - thyroid in particular
ECHO

How well did you know this?

Not at all

Perfectly

Describe the therapy for arrhythmias

Digoxin - AF
Beta blockers - lowers HR
Calcium antagonists
Warfarin or aspirin 
Anti-arrhythmic drugs
DC conversions
Pace and ablation of AV node
Anti-coagulation

How well did you know this?

Not at all

Perfectly

Describe the Singh-Vaughan Williams classification of anti-arrhythmic drugs

I - interferes with Na channel
II - anti-symp NS agents e.g. beta blockers
III - interferes with K+ efflux
IV - affects Ca channels and AV node
V - other/unknown mechanism

How well did you know this?

Not at all

Perfectly

What is supraventricular tachycardia?

Abnormally fast heart rate (150-250bpm) arising from improper electrical activity in the upper part of the heart: re-entry or increased automaticity

Normal rhythm, P waves not discernable

How well did you know this?

Not at all

Perfectly

How do you treat supraventricular tachycardia?

Often don’t require any treatment

Radiofrequency ablation to the abnormal electrical pathways of the heart, good success rate

How well did you know this?

Not at all

Perfectly

What are the 4 main types of supra ventricular tachycardia?

Atrial fibrillation
Wolff-Parkinson-White syndrome
Paroxysmal supraventricular tachycardia
Atrial flutter

How well did you know this?

Not at all

Perfectly

What is atrial flutter?

Common abnormal heart rhythm starting in the atria, associated with a fast HR (100+bpm), and is classified as a type of supraventricular tachycardia

How well did you know this?

Not at all

Perfectly

What causes atrial flutter?

CVD disease - hypertension, CAD, CM
DM
Spontaneously with no cardiac defect

How well did you know this?

Not at all

Perfectly

What is a complication of atrial flutter?

Can degenerate into atrial fibrillation

How well did you know this?

Not at all

Perfectly

Describe the conduction and rhythm in atrial flutter

Atrial rate is typically 300bpm, while ventricular rate is 150bpm, meaning only one flutter in 2 is conducted

Abnormal rhythm, sawtooth flutter F waves

How well did you know this?

Not at all

Perfectly

How can you transiently impair conduction to more easily identify atrial flutter?

Drugs

Carotid sinus massage

How well did you know this?

Not at all

Perfectly

Describe the treatment of atrial flutter

Radiofrequency catheter ablation of re-entry circuit is often curative

Can be treated like AF

How well did you know this?

Not at all

Perfectly

What is the most common arrhythmia?

Atrial fibrillation - seen in 5-10% of >65yo and paroxysmally in younger patients

How well did you know this?

Not at all

Perfectly

Describe atrial fibrillation

Atrial activity is chaotic and mechanically ineffective, conducting a proportion of the AV impulses to produce an irregular ventricular response

Irregularly irregular pulse, fibrillation f waves, no P waves

How well did you know this?

Not at all

Perfectly

What are some symptoms of atrial fibrillation?

Palpitations
Fatigue
Acute heart failure
No symptoms - incidental finding

How well did you know this?

Not at all

Perfectly

Describe ventricular fibrillation

Very rapid and irregular ventricular activation (300-600bpm) with no mechanical effect and hence no cardiac output. No p waves

Pulseless, unconscious, respiration ceases (cardiac arrest) - medical emergency

How do you treat those with ventricular fibrillation?

Immediate defibrillation (follow cardiac arrest protocol)

After revived, given ICD to reduce risk of sudden death

Describe ventricular tachycardia and its symptoms

Rapid ventricular rate (120-250bpm), broad QRS complexes, no P waves preceding QRS (unassociated)

Palpitations, chest pain, dyspnoea, dizziness and syncope

What two arrhythmias are more associated with underlying structural heart disease?

Ventricular tachycardia

Ventricular fibrillation

When is ventricular tachycardia considered ventricular flutter

bpm >250

What arrhythmias cause broad QRS complexes?

Ventricular tachycardia
Supraventricular tachycardia with BBB
Bundle branch blocks

Rule out with aid of ECG analysis

How do you treat ventricular tachycardia?

Urgent DC conversion
IV lidocaine or amiodarone

Recurrence prevented with

beta blockers
other anti-arrhythmias
ICD

What investigations are used for ventricular tachycardia?

ECG - rule our SVT with BBB Bloods - thyroid ECHO Angiogram

What is Torsades de Pointes?

Abnormal heart rhythm that can lead to sudden death, characterised by short-long-short RR intervals followed by TdP (looks like twirling party streamer) Type of polymorphic ventricular tachycardia which can resolve itself or cause symptoms such as palpitations, syncope, pre-syncope and sudden cardiac death

How do you treat Torsades de Pointes?

``` Remove cause (e.g. drugs) if appropriate Infusion of magnesium sulfate Anti-arrhythmic drugs Electrical therapy Defibrillation ```

What is long QT syndrome?

Prolonged ventricular repolarisation period that cause symptoms such as palpitations and syncope, that can degenerate into TdP or VF

What causes long QT syndrome?

Congenital mutations in Na and K channels Electrolyte disturbances Variety of drugs

How do you treat long QT syndrome?

Treat underlying cause Remove drugs IV isoprenaline

When is ICD implantation indicated?

High risk of sudden cardiac death Cardiac arrest due to transient or non-reversible cause Sustained VT causing syncope Sustained VT with poor lV function

What are some common causes of heart block?

CAD Cardiomyopathy Fibrosis of conduction tissue of heart

What is heart block?

Heart block is a disease or inherited condition that causes a fault within the heart's natural pacemaker due to some kind of obstruction (or "block") in the electrical conduction system of the heart, causing an abnormal rhythm where the heart beats too slowly

Where does the block have to be for AV block?

Block in AV node or His bundle

Where does the block have to be for left or right bundle branch block?

Lower conduction system e.g. Purkinje fibres

Describe 1st degree AV block

Prolonged PR interval but rate is normal

Describe 2nd degree type I AV block

Progressive PR elongation until QRS drops, then back to normal

Describe 2nd degree type II AV block

Constant prolonged PR intervals, random QRS complexes dropped

Describe 3rd degree AV block

Totally unrelated P and QRS waves

Describe RBBB on ECG

Secondary r wave in VI | Slurred S wave in V5 and V6

Describe LBBB on ECG

RSR pattern in LV leads (I, AVL, V4-6) | Slurred S in V1 and V2

What are some indications for temporary pacing?

Intermittent/sustained symptomatic bradycardia | When at high risk of severe bradycardia e.g. 2nd/3rd degree AV block, post anterior MI

What are some indications for permanent pacing?

``` Symptomatic 2nd/3rd degree block AV block with NMD With AV ablation RBBB/LBBB Syncope Sinus node disease Carotid sinus hypersensitivity Malignant vasovagal syncope ```