Cardiac Arrhythmias

What if the patient is haemodynamically unstable?

Increase vagal stimulation - valsalva manoeuvre / carotid sinus massage Adenosine - AV blocking drug - terminates the junctional tachcardia IV verapamil Beta blockers - metoprolol

Outline the causes of heart block

coronary artery disease fibrosis of conducting tissue cardiomyopathy in the elderly

What symptoms occur with third degree HB at the purkinje fibres?

dizziness blackouts (Stokes Adams attacks)

What is mobitz type II HB?

dropped QRS complex not preceded by progressive prolongation of PR interval

what does sick sinus syndrome predispose to?

ectopic pacemaker activity tachyarrhythmias (Tachy-Brady syndrome is seen)

What is 2:1 /3:1 HB?

every second or third P wave conducts to the ventricle (QRS complex seen after two or three P waves)

when is sinus tachycardia a physiological response?

exercise, excitement

What can aggravate the arrhythmias?

exertion alcohol coffee

What do patients with ventricular ectopic premature beats complain of?

extra beats missed beats heavy beats

How can bradycardias be categorised?

extrinsic intrinsic neurogenic

what is sick sinus syndrome?

failure of the SAN to depolarise (sinus arrest) failure of propagation to perinodal tissue (SAN block)

when else can sinus tachycardia occur?

fever anaemia heart failure thyrotoxicosis acute PE hypovolaemia drugs (catecholamines, atropine)

What happens in sinus arrhythmia?

fluctuations of autonomic tone; causes phasic changes in discharge rate

define tachycardia

heart rate greater than 100 beats per minute

define bradycardia

heart rate less than 60 beats per minute

What is the problem in survivors?

high risk of sudden death so treat with ICD

What if the patient is haemodynamically unstable?

immediate heparinisation cardioversion IV amiodarone - if fails reattempt; can given 2 doses

When does neurogenic bradycardia occur?

in carotid sinus syndrome vasovagal attacks

What are the causes of left bundle branch block?

ischaemic heart disease left ventricular hypertrophy aortic valve disease post cardiac surgery

If third degree HB occurs at the bundle of his what is shown on the ECG?

narrow QRS complex <0.12 secs slow heart rate 50-60 bpm

What happens in right bundle branch block?

no impulse propagated along the right bundle branch the two ventricles do not contract simultaneously spread from left ventricle to right ventricle secondary R wave (RSR) in V1 slurred S wave V5, V6

What is seen on the ECG?

no p waves fibrillation f waves

What does the ECG of ventricular ectopic show?

not conducted to ventricle through normal conducting tissue QRS complex is widened strange configuration

How are they treated?

oxygen IV access and fluid replacement

What are the symptoms of long QT syndrome?

palpitations syncope

How is the atrial ectopic treated?

palpitations are treated with beta blockers

What typically happens on inspiration?

parasympathetic tone decreases - increase in HR

what happens on expiration?

parasympathetic tone increases - decrease in HR

how is sick sinus syndrome treated?

permanent pacemaker temporary pacemaker (transcutaneous, transvenous) anti-arrhythmic drugs for the tachycardia - beta blocker anticoagulation for risk of thromboembolism ATROPINE for acute bradycardia

How is third degree HB with purkinje fibres treated?

permanent pacing

What does long QT syndrome increase the risk of?

polymorphic VT torsades de pointes rapid, regular sharp QRS complex switch between being upright and inverted

What happens in an atrial ectopic?

premature discharge of ectopic atrial focus

What is mobitz type I (wenckebach) HB?

progressive PR interval prolongation until P wave fails to conduct (no QRS complex after P wave) P wave then returns to normal, cycle repeats

What is seen on the ECG in first degree HB?

prolonged PR interval >0.22 seconds no change heart rate

How does the patient with VF present?

pulseless apnoeic unconcious

What is the long term management?

radiofrequency ablation of accessory pathway via cardiac catheter flecainide, verapamil, sotalol, amiodarone

How is atrial flutter treated?

radiofrequency ablation of re-entry circuit

What does sustained ventricular tachycardia show on an ECG?

rapid ventricular rhythm broad QRS complexes

What are the associated symptoms?

rapid, regular palpitations (abrupt onset, terminate suddenly) dizziness syncope dyspnoea chest pain

What is third degree HB at the BOH due to?

recent onset ischaemia

What is the acute management?

restore/maintain sinus rhythm

How is cardiac arrest treated?

resuscitation (stop when return of spontaneous circulation/pulse) post resus - maintain O2 saturations 94-98%, blood glucose <10mmol/L, therapeutic hypothermia

What is AVNRT?

ring of conducting tissue in the AV node limbs of the ring have differing conducting times and refractory periods re-entry circuit forms

What does the ECG show?

sawtooth appearance - flutter waves

what are the signs and symptoms of arrhythmias?

severe pulmonary oedema low cardiac output hypotension impaired conciousness cold, clammy extremities

What does the ECG show then?

shortened PR interval (early depolarisation) slurred start to the QRS complex (DELTA WAVE) narrow QRS complex

what does the ECG show in sick sinus syndrome?

sinus bradycardia with pauses in between p waves

What happens in second degree HB?

some of the atrial impulses fail to reach the ventricles

What are ventricular contractions in third degree HB due to?

spontaneous escape rhythm originating below the site of the block

what does AF increase the risk of?

stroke

What can arrhythmias cause?

sudden death, syncope, dizziness, palpitations

How can tachycardias be divided?

supraventricular tachycardias ventricular tachycardias

what are atrioventricular junctional tachycardias?

tachycardia due to re-entry circuits 2 pathways for conduction paraoxysmal SVTs - young patients

what is a supraventricular tachycardia?

tachycardia of the atria/ atrioventricular junction

What happens in AF?

the atrial activity is choatic and the atria becomes mechanically ineffective Av node conducts a proportion of atrial impulses, but this results in an irregular ventricular response

what is the rate of discharge under control of?

the autonomic nervous system (parasympathetic NS predominantly) this slows the spontaneous discharge rate

What happens in left bundle branch block?

the opposite to right bundle branch block secondary R wave (RSR) in lead I, AVL, V4-6 deep S wav in V1, V2

what is the normal cardiac pacemaker?

the sinoatrial node

What happens in first degree heart block?

there is prolonged conduction at the atrioventricular node

How is AF managed?

treat the precipitating factor; e.g. alcohol, toxicity, chest infection, hyperthyroidism

how is extrinsic bradycardia managed?

treat the underlying cause

What is the treatment for sinus tachycardia?

treat the underlying cause beta blockers can slow the sinus rate

How is it treated?

urgent DC cardioversion if haemodynamically compromised IV lidocaine/ amiodarone

What is ventricular fibrillation?

very rapid, irregular ventricular activation no mechanical effect so NO CARDIAC OUTPUT

When is sinus bradycardia normal?

when sleeping/ in athletes

What does a bundle branch block show on ECG?

wide QRS complex with abnormal pattern

How long does it take for irreversible brain damage to occur in cardiac arrest?

3 minutes

When does atrial fibrillation present?

5-10% >65 years are affected younger - paroxysmal

when does intrisic bradycardia occur?

1) acute ischaemia/ infarct of sinoatrial node (complication of myocardial infarction) 2) chronic degenerative conductions - fibrosis of the atria and sinoatrial node (sick sinus syndrome)

What if the patient is stable?

1) control heart rate - beta blockers - calcium antagonists - sedentary lifestyle give digoxin 2) control rhythm (young patients <65 yrs and symptomatic patients) cardioversion using beta blockers If HD present - amiodarone No HD - sotalol, flecainide, propafenone patients with infrequent symptomatic paraoxysmal AF, e.g. 1/ month - pill in pocket approach with oral flecainide/ propafenone 3) assess for anticoagulation as AF increase risk of thromboembolism warfarin; aim for INR around 2-3 young patients - aspirin

When does extrinsic bradycardia occur?

1) drugs - beta blockers, digoxin 2) hypothyroidism 3)hypothermia 4)cholestatic jaundice 5) raised intracranial pressure

What causes long QT syndrome?

1)congenital problems with sodium and calcium channel genes 2) electrolyte disturbances - hypokalaemia - hypocalcaemia - hypomagnesaemia 3) drugs - tricyclic antidepressants, phenothiazines, macrolide antibiotics

What does the ECG show in atrial ectopic?

ECG - early/abnormal P wave, normal QRS

What causes atrial tachyarrhythmias?

IHD rheumatic HD thyroitoxicosis cardiomyopathy lone AF WPW syndrome pneumonia atrial septal defect bronchial carcinoma pericarditis PE cardiac surgery acute on chronic alcohol use

How is VF treated?

IMMEDIATE DEFIBRILLATION

What does it respond to?

IV Atropine - no needed for pacing

How is long QT syndrome treated?

IV isoprenaline

When does WPW syndrome show on an ECG?

If the accessory path allows some atrial depolarisation to pass to the ventricle before entering the AV node

What are the three types of second degree heart block called?

Mobitz type I (wenckebach) Mobitz type II 2:1/3:1

Is treatment necessary in first degree HB?

No just monitoring

What does the ECG show in AVNRT?

P waves absent or P waves present immediately before the QRS complex QRS complex of normal shape (activated normally) occasionally wide QRS complex

What happens in cardiac arrest?

There is no effective cardiac output patient is unconcious, apnoeic, absent arterial pulses (carotid arteries)

What is non-sustained ventricular tachycardia?

VT >5 consecutive beats lasts less than 30 seconds occurs in patient with heart disease

What is third degree HB?

When atrial activity fails to conduct to the ventricles NO ASSOCIATION BETWEEN P WAVES AND QRS COMPLEXES

What is long QT syndrome?

When ventricular repolarisation is prolonged prolonged QT interval

What syndrome is defined by AVRT?

Wolf Parkinson's White syndrome

What is an arrhythmia?

abnormality of cardiac rhythm

What is an AVRT?

accessory pathway - connects atria and ventricles can be retrograde or anterograde conduction

What does this irregular ventricular response cause?

an irregularly irregular pulse

What is atrial flutter?

associated with AF atrial rate 300bpm AV node conducts every second flutter beat ventricular rate 150bpm

what does the term atrial tachyarrhythmia encompass?

atrial fibrillation, atrial flutter

If a conduction block occurs at the AV node or the bundle of his what is it called?

atrioventricular block

What does AVNRT stand for?

atrioventricular nodal re-entry tachycardia

What is AVRT?

atrioventricular reciprocating tachycardia

How are ventricular ectopics treated?

beta blockers

How is it treated?

beta blockers ICD

How is recurrence prevented?

beta blockers implantable cardioverter-defibrillator

If third degree HB occurs at the purkinje fibres what is shown on the ECG?

broad QRS complex >0.12 secs slow heart rate 40bpm

if a conduction block occurs at the bundle branch what is it called?

bundle branch block

What are the causes of right bundle branch block?

can occur in normal individuals pulmonary embolus right ventricular hypertrophy ischaemic heart disease congenital heart disease (atrial septal defect) Fallots teratology