Arrhythmias and ECG Changes Flashcards
Describe the tachycardia algorithm
ABCDE assessment
If adverse features (shock, syncope, HF, MI) emergency synchronised direct current cardioversion
If haemodynamically stable, management defers on if the tachycardis is narrow (QRS>120) or broad complex (QRS<120)
For regular narrow, vagal manoeuvres is first line, followed by IV 6mg adenosine, followed by further 12mg
For irregular narrow, if <48 hours rhythm control and rate control if >48 hours
What is atrial fibrillation?
Disorganised atrial activity resulting in irregularly-irregular AV node stimulation and therefore disregular ventricular response
What are the types of AF?
First detected episode
Paroxysmal
- <7 days, typically <24 hours
- Episodes terminate spontaneously
Persistent
- >7 days
- Amenable to cardioversion
Permanent
- >7 days
- Not amenable to cardioversion
What are the causes of atrial fibrillation?
HTN
Lung disease
- PE, Pneumonia
Ischaemic heart disease
Heart failure
Rheumatic heart disease
Hypoxia
Alcohol/Caffeine
Hypercapnia
Mitral stenosis
Atrial septal defect
Thyrotoxicosis
Sepsis
Metabolic abnormalities
Describe the presentation of atrial fibrillation
Palpitations
Fatigue
Chest pain
Dizziness
Dyspnoea
Irregularly Irregular pulse
Apical to radial pulse deficit
What ECG signs are seen in atrial fibrillation?
Absent P waves
Irregular QRS complex, but normal shape, so therefore an irregular rate
What is involved in rate control of AF?
ABCD
B Blocker, first line
- Bisoprolol
- Contraindicated in asthma, hypotension
CCB, first line
- Verapamil
- Contraindicated in HF
Digoxin, second line
- Used in hypotension or co-existent HF
- Contraindicated in younger patients because it increases cardiac mortality
When should rate control be offered in AF?
Offer rate control as the first-line strategy to people with AF, except in people
- Whose AF has a reversible cause
- Who have heart failure thought to be primarily caused by AF
- With new-onset AF
- For whom a rhythm control strategy would be more suitable based on clinical judgement
What is involved in rhythm control of AF?
AF = Amiodarone and Flecainide
Amiodarone
- Older sedentary patients
Flecainide
- Young patients with structurally normal hearts
Direct current cardioversion
- If acute/<48 hours can be cardioverted with sedation
- If >48 hours patient has to be anticoagulated for 3 weeks before cardioversion
What is the mechanism of amiodarone?
Blocking potassium channels which inhibits repolarisation and hence prolongs the action potential
Give adverse effects of amiodarone
Thyroid dysfunction, both hypothyroidism and hyper-thyroidism
Corneal deposits
Pulmonary fibrosis/pneumonitis
Liver fibrosis/hepatitis
Peripheral neuropathy, myopathy
Photosensitivity
‘Slate-grey’ appearance
Thrombophlebitis and injection site reactions
Bradycardia
Lengths QT interval
What score assesses the risk of stroke in AF?
CHAD VASC 2
What factors does the CHADS VAS score take into consideration?
C point for congestive cardiac failure
H 1 point for hypertension
A2 2 points if the patient is aged 75 or over.
D 1 point if the patient has diabetes mellitus.
S2 2 points if the patient has previously had a stroke or transient ischaemic attack (TIA)
V 1 point if the patient has known vascular disease
A 1 point if the patient is aged 65-74
S 1 point if the patient is female
What are the groups of anticoagulants?
Vitamin K Antagonists
DOAC (direct oral anticoagulant)
- Direct thrombin inhibitors
- Direct factor Xa inhibitors
Low molecular weight heparins
When are anti-cogulants used in AF?
Males who score 1 or more or females who score 2 or more should be anticoagulated
What anticoagulants are used in AF?
Warfarin
- Requires cover with LMWH for 5 days
- Only drug lisenced for valvular AF
DOACS
- Patients are not covered if they miss doses
- Use if require anticoagulation but unable to carry out regular monitoring
LMWH
- Rare option in those who cannot tolerate oral
When should anticoagulation be started for patients with AF after a stroke?
2 weeks
What is the mode of action of warfarin?
Inhibits thromboxane
Give side effect of warfarin
Haemorrhage
Teratogenic, although can be used in breastfeeding mothers
Skin necrosis
Purple toes
What has to be monitored with warfarin?
INR (International normalised ration)
The ratio of the prothrombin time for the patient over the normal prothrombin time
What is the INR target for AF?
2.5
What drugs can increase INR (inhibitors of P450 system)?
STICKFACE.COM
Sodium valproate
Ticlodipine
Isoniazid
Cimetidine
Ketoconazole
Fluconazole
Alcohol, Amiodarone
Ciprofloxacin
Erythomycin
Sulfonamides
Chlorampenicol
Omeprazole
Metronidazole
What drugs can decrease INR (inducers of the P450 system?)
BS CRAP GPS
Barbituates
St John’s wort
Carbamezapine
Rifampicin
Alcohol (chronic)
Phenytoin
Griseofluvin
Phenobarbital
Sulphonylureas
How do you manage INR of 5.0-8.0 with no bleeding?
Withhold 1 or 2 doses of warfarin
Reduce subsequent maintenance dose
How do you manage INR of 5.0-8.0 with minor bleeding?
Stop warfarin
Give intravenous vitamin K 1-3mg
Restart when INR <5.0
How do you manage INR >8.0 with no bleeding?
Stop warfarin
Give vitamin K 1-5mg by mouth, using the intravenous preparation orally
Repeat dose of vitamin K if INR still too high after 24 hours
Restart when INR < 5.0
How do you manage INR >8.0 with minor bleeding?
Stop warfarin
Give intravenous vitamin K 1-3mg
Repeat dose of vitamin K if INR still too high after 24 hours
Restart warfarin when INR < 5.0
How do you manage major bleeding with high INR?
Stop warfarin
Give intravenous vitamin K 5mg
Prothrombin complex concentrate,if not available then FFP
How do you manage INR <2?
Increase dose of warfarin and start LMWH
How long before surgery should warfarin be stopped?
In general, warfarin is usually stopped 5 days before planned surgery, and once the person’s INR is less than 1.5 surgery can go ahead
What is the preferred NOAC used in AF for renal impaired patients?
Apixaban
What is atrial flutter?
SVT characterised by a succession of rapid atrial depolarisation waves
What ECG signs are present in atrial flutter?
Sawtooth P waves due to AV block
High QRS rate
Flutter waves may be visible following carotid sinus massage or adenosine
How is atrial flutter managed?
Similar to AF although medication may be less effective
More sensitive to cardioversion however so lower energy levels may be used
Radiofrequency ablation of the tricuspid valve isthmus is curative for most patients
What are the two types of SVT?
Atrioventricular retentry tachtcardia (AVRT)
Atrioventricular nodal reentrant tachycardias (AVNRT)
How can SVT be prevented?
B blockers
Radio-frequency ablation
How are SVT managed?
Vagal manoeuvres
- Valsalva manouvre
- carotid sinus massage
IV 6mg Adenosine, infused via large cannula
Followed by further 12mg Adenosine
Later bolus can be repeated until a total of 30mg adenosine
What is used instead of adenosine for SVT management in asthmatics?
Verapamil
Give adverse affects of adenosine
Chest pain
Bronchospasm, avoid in asthmatics
Transient flushing
Can enhance conduction down accessory pathways, resulting in increased ventricular rate (e.g. WPW syndrome)
Infused via large calibre cannula due to short half life (8-10 seconds)
What is wolf parkinson white syndrome?
Atrioventricular re-entry tachycardia (AVRT) caused by a congenital accessory pathway between the atria and ventricles
What ECG signs are seen in WPW?
Short PR interval
Wide QRS complexes with a slurred upstroke, known asdelta wave
Left axis deviation if right-sided accessory pathway
Right axis deviation if left-sided accessory pathway
What is the management of WPW?
Definitive management
- Radiofrequency catheter ablation of accessory pathway
Medical therapy
- Amiodarone
What is ventricular tachycardia?
Broad-complex tachycardia in which heart rate originates in ventricles/does not start in SA node
What ECG signs are seen in ventricular tachycardia?
Regular broad QRS complex
No P waves
What are the types of ventricular tachycardia?
Monomorphic VT
- Most commonly caused by myocardial infarction
Polymorphic VT
- Prolongation of the QT interval
How is ventricular tachycardia managed?
Emergency unsynchronised direct current cardioversion, if no palpable pulse (+chest compressions at 100-120bpm)
300mg IV amiodarone
- Administered in shockable rhythms after delivery of 3rd shock
- Once off dose
1mg IV adrenalin (1:10,000)
- Administered in shockable rhythms after delivery of 3rd shock
- Repeated every other cycle following a shock
Implantable Cardioverter Defibrillator
- If drug therapy fails
What drug is contraindicated in ventricular tachycardia?
Verapamil
What is ventricular fibrillation?
Medical emergency in which there is chaotic depolarisation of ventricles, resulting in arrested pump function and CO
What are the causes of ventricular fibrillation?
Hypoxia
Hypothermia
Metabolic
- Hyperkalaemia
- Hypokalaemia
- Hypoglycaemia
- Hypocalcaemia
Thrombosis, coronary or pulmonary
Tension pneumothorax
Cardiac tamponade
What are the ECG signs in ventricular fibrillation?
Irregular rhythm
Unformed QRS
No P waves
What is the management of ventricular fibrillation?
Emergency unsynchronised direct current cardioversion
- Give up to 3 shots followed by CPR if no improvement
300mg IV amiodarone
- Administered in shockable rhythms after delivery of 3rd shock
- Once off dose
1mg IV adrenalin (1:10,000)
- Administered in shockable rhythms after delivery of 3rd shock
- Repeated every other cycle following a shock
How are non shockable rhythms/pulseless electrical activity managed?
IV adrenalin immediately
What is Torsade’s de Pointes?
Polymorphic ventricular tachycardia associated with a long QT interval, which may deteriorate into ventricular fibrillation and hence lead to sudden death
What ECG signs are seen in Torsade’s de pointes?
Varied QRS in amplitude, axis and duration
Twisted QRS
What is the management of Torsade’s de pointes?
IV magnesium sulphate
What is long QT syndrome?
Inherited condition associated with delayed repolarization of the ventricles, which may lead to ventricular tachycardia/torsade de pointes and can therefore cause collapse/sudden death
What are the causes of long QT syndrome?
Congenital
Electrolyte disturbance
- Hypokalaemia
- Hypocalcaemia
- Hypomagnesaemia
Drugs
- Amiodarone
- Erythromycin, Clarithromycin
- TCA
- Antipsychotics
MI
Myocarditis
Hypothermia
Subarachnoid haemorrhage
How is long QT syndrome managed?
B Blockers
Implantable cardioverter defibrillator
How is symptomatic bradycardia managed?
500mcg IV atropine, up to maximum 3mg
Transcutaneous/external pacing if atropine fails
Adrenaline infusion
What is first degree heart block?
Delay in transmission of impulses between AV node to ventricles, causing a fixed prolonged PR interval
What is second degree heart block type 1?
Progressive PR prolongation until p wave no longer conducts through and QRS is dropped
What is second degree heart block type 2?
Normal/constant PR interval with randomly dropped QRS
What is third degree heart block?
Complete AV node block, meaning p waves are not associated with QRS at all
How is heart block managed?
IV atropine, acute setting with hypotension
Transcutaneous/external pacing if atropine fails
Mobitz type 2, pacemaker
What is bundle branch block?
Block of electrical signal at one bundle branch, causing one ventricle to contract late
What are the ECG signs of bundle branch block?
Right
- Broad QRS
Left
- Broad QRS
What cause ST elevation?
MI
Pericarditis/myocarditis
Normal variant/’high take-off’
Left ventricular aneurysm
Prinzmetal’s angina/coronary artery spasm
Takotsubo cardiomyopathy
Subarachnoid haemorrhage, although rare
What causes ST depression?
Secondary to abnormal QRS (LVH, LBBB, RBBB)
Ischaemia
Digoxin
Hypokalaemia
Syndrome X
What causes peaked/tall t waves?
Hyperkalaemia
Myocardial ischaemia
What causes inverted t waves?
BBB
Ischaemia/infRCT
PE
Ventricular cardiomyopathy
Digoxin toxicity
Subarachnoid haemorrhage
Brugada syndrome
Normal in children
What caues prolonged PR interval?
Idiopathic
Ischaemic heart disease
Digoxin toxicity
Hyperkalaemia
Rheumatic fever
Aortic root pathology
Lyme disease
Sarcoidosis
Myotonic dystrophy
Athletes
What causes shortened PR interval?
WPW syndrome
What causes increased p wave amplitude?
Cor pulmonale
What causes broad notched/bifid p waves?
Left atrial enlargement, mitral stenosis
What ecg changes can be seen in hypothermia?
Bradycardia
‘J’ wave, small hump at the end of the QRS complex
First degree heart block
Long QT interval
Atrial and ventricular arrhythmias
what ecg features can be seen in hypokalaemia?
U waves
Small or absent T waves, occasionally inversion/flattening
Prolonged PR interval
ST depression
Long QT
What ecg signs are seen in hyperkalaemia?
Peaked t waves
Flat/abscent p waves
Increased pr interval
Abnormal QRS
What ecg features can be seen with digoxin?
Down-sloping ST depression (‘reverse tick’, ‘scooped out’)
Flattened/inverted T waves
Short QT interval
Arrhythmias such as AV block, bradycardia
What is seen in this ecg?
U waves
