Arrythmia Flashcards
What is the most common sustained cardiac arrhythmia?
Atrial fibrillation (AF)
> 70-75 years (5%)
> 80-85 years (10%)
What is the most important important aspect of managing patients with Atrial Fibrillation?
reducing the increased risk of stroke
What can uncontrolled atrial fibrillation can result in?
symptomatic palpitations
inefficient cardiac function
What are the types of atrial fibrillation?
first detected episode
recurrent: 2 or more episodes of AF
permanent: continuous AF which cannot be cardioverted
two types of recurrent atrial fibrillation
paroxysmal: terminates spontaneously; episodes last less than 7 days (< 24 hours)
persistent: not self-terminating; episodes last greater than 7 days
treatment goals of permanent AF
rate control
anticoagulation if appropriate
AF signs and symptoms
symptoms: palpitations, dyspnoea, chest pain
signs: irregularly irregular pulse
conditions (other than AF) that can give an irregular pulse
ventricular ectopics or sinus arrhythmia.
What investigation is essential for diagnosis of AF?
ECG
key parts of managing patients with AF
- rate/rhythm control
- rate control: accept pulse will be irregular but slow rate down to avoid negative effects on cardiac function
- rhythm control: cardioversion (to maintain normal sinus rhythm) using drugs (pharmacological) or synchronised DC electrical shocks (electrical)
- reducing stroke risk
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contraindications for rate control
coexistent heart failure
first onset AF
obvious reversible cause
(note: patients may have had a rate control strategy initially but switch to rhythm control if symptoms/heart rate fails to settle)
medications used for rate control in AF
beta-blocker or a rate-limiting calcium channel blocker (diltiazem)
combination therapy with any 2 of the following:
(if one drug does not control the rate adequately)
- a betablocker
- diltiazem
- digoxin
when is the highest risk for embolism leading to stroke in cardioversion ?
the moment a patient switches from AF to sinus rhythm
prior to attempting cardioversion, why must patients either have had a:
- short duration of symptoms (less than 48 hours)
- anticoagulated for a period of time
in cardioversion, the moment a patient switches from AF to sinus rhythm presents the highest risk for embolism leading to stroke.
how to identify most appropriate anticoagulation for reducing stroke risk in AF?
CHA2DS2-VASc
what does CHA2DS2VASc consist of
C ongestive ♡ failure (1)
H ypertension (or treated hypertension) (1)
A ge >= 75 years (2)
D iabetes (1)
S troke or TIA (2)
V ascular disease (1)
A ge 65-74 years (1)
S ex - female (1)
suggested anticoagulation strategy based on the CHA2DS2-VASc score
0: no treatment
1: males: consider anticoagulation
females: no treatment (as score only reached due to gender)
2 or more: anticoagulation
What is a common contraindication for beta-blockers
asthma
preferred rate control medication if there is coexistent heart failure
Digoxin
not considered first-line anymore as they are less effective at controlling the heart rate during exercise
rhythm control agents in patients with a history of atrial fibrillation
sotalol
amiodarone
flecainide
factors favouring rate control in AF
> 65 years
history of ischaemic heart disease
factors favouring rhythm control in AF
< 65 years
symptomatic
first presentation
lone AF or secondary to a corrected precipitant (e.g. Alcohol)
congestive heart failure
indications for catheter ablation
not responded or wish to avoid antiarrhythmic medication.
technical aspects of catheter ablation
aim is to ablate faulty electrical pathways- due to aberrant electrical activity between pulmonary veins and left atrium - that result in AF
procedure is performed percutaneously, typically via the groin
can use:
- radiofrequency (uses heat generated from medium frequency alternating current)
- cryotherapy
when should anticoagulation be started for patients undergoing catheter ablation
4 weeks before and during the procedure
therefore, patients still require anticoagulation afterwards as per theire CHA2DS2-VASc score
if score = 0: 2 months anticoagulation recommended
if score > 1: longterm anticoagulation recommended
complications of catheter ablation?
cardiac tamponade
stroke
pulmonary valve stenosis
success rate of catheter ablation
50%: early recurrence (3 months); often resolves spontaneously
55%: long term (3 years) sinus rhythm with one procedure
80%: long term (3 years) sinus rhythm with multiple procedures
When would cardioversion be used in atrial fibrillation?
- emergency if patient is haemodynamically unstable (electrical cardioversion)
- elective procedure where rhythm control strategy is preferred (electrical or pharmacological cardioversion)
why is electrical cardioversion is synchronised to the R wave
to prevent delivery of a shock during the vulnerable period of cardiac repolarisation when ventricular fibrillation can be induced.
AF onset <48 hours
indications prior to cardioversion
begin heparin
if risk factors for ischaemic stroke: lifelong oral anticoagulation.
may be cardioverted electrically or pharmalogically.
Following electrical cardioversion if AF is confirmed as being less than 48 hours duration then further anticoagulation is?
unnecessary
AF onset >48 hours
when should anticoagulation be given
at least 3 weeks prior to cardioversion
an alternative strategy:
- transoesophageal echo (TOE) to exclude a left atrial appendage (LAA) thrombus
- if excluded: patients may be heparinised and cardioverted immediately
AF onset >48 hours
which cardioversion?
electrical
What suggests a high risk of cardioversion failure?
Previous failure or AF recurrence
AF onset >48 hours & high risk of cardioversion failure
what should you do
4 weeks amiodarone or sotalol prior to electrical cardioversion
AF onset >48 hours
anticoagulation after electrical cardioversion ?
anticoagulation for at least 4 weeks.
after this time decisions about anticoagulation should be taken on an individual basis depending on the risk of recurrence
pharmacological cardioversion agents (effective ones)
amiodarone
flecainide (if no structural heart disease)
pharmacological cardioversion agents (less effective)
beta-blockers (including sotalol)
calcium channel blockers
digoxin
disopyramide
procainamide
If CHA2DS2-VASc score suggests no need for anticoagulation it is important to ensure what?
transthoracic echocardiogram
to exclude valvular heart disease, which in combination with AF is an absolute indication for anticoagulation.
NICE recommend that we offer patients a choice of anticoagulation
true
warfarin and the novel oral anticoagulants (NOACs)
Aspirin is no longer recommended for reducing stroke risk in patients with AF
true
A history of what make us consider whether warfarinisation is in the best interests of the patient?
falls, old age, alcohol excess and a history of previous bleeding
NICE now recommend we formalise risk assessment for wararin prescription using what system?
HASBLED
There are no formal rules on how we act on the HAS-BLED score
true
A HASBLED score of what indicates ‘high risk’ of bleeding?
> = 3
defined as intracranial haemorrhage, hospitalisation, haemoglobin decrease >2 g/L, and/or transfusion.
Outline HASBLED score
H Hypertension, uncontrolled, systolic BP > 160 mmHg 1
A Abnormal renal function (dialysis or creatinine > 200)
Or
Abnormal liver function (cirrhosis, bilirubin > 2 times normal, ALT/AST/ALP > 3 times normal 1 for any renal abnormalities
1 for any liver abnormalities
S Stroke, history of 1
B Bleeding, history of bleeding or tendency to bleed 1
L Labile INRs (unstable/high INRs, time in therapeutic range < 60%) 1
E Elderly (> 65 years) 1
D Drugs Predisposing to Bleeding (Antiplatelet agents, NSAIDs)
Or
Alcohol Use (>8 drinks/week) 1 for drugs
1 for alcohol
following a stroke or TIA, what should be given as the anticoagulant of choice?
warfarin or a direct thrombin or factor Xa inhibitor (Rivaroxaban, Apixaban)
Antiplatelets should only be given if needed for the treatment of other comorbidities
In acute stroke patients, in the absence of haemorrhage, anticoagulation therapy should be commenced after?
2 weeks. If imaging shows a very large cerebral infarction then the initiation of anticoagulation should be delayed
Atrial flutter is a form of supraventricular tachycardia characterised by?
succession of rapid atrial depolarisation waves.
What are the ECG findings in atrial flutter?
‘sawtooth’ appearance
as the underlying atrial rate is often around 300/min the ventricular or heart rate is dependent on the degree of AV block. For example if there is 2:1 block the ventricular rate will be 150/min
flutter waves may be visible following carotid sinus massage or adenosine
How do you manage atrial flutter?
is similar to that of atrial fibrillation although medication may be less effective
atrial flutter is 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 is Ventricular tachycardia?
broad-complex tachycardia originating from a ventricular ectopic focus. It has the potential to precipitate ventricular fibrillation and hence requires urgent treatment.
What are the two main types of VT?
monomorphic VT: most commonly caused by myocardial infarction
polymorphic VT: A subtype of polymorphic VT is torsades de pointes which is precipitated by prolongation of the QT interval.
What are the congenital causes of prolonged QT interval?
Jervell-Lange-Nielsen syndrome (includes deafness and is due to an abnormal potassium channel)
Romano-Ward syndrome (no deafness)
What are the drug causes of prolonged QT interval?
amiodarone, sotalol, class 1a antiarrhythmic drugs tricyclic antidepressants, fluoxetine chloroquine terfenadine erythromycin
What are the other causes of prolonged QT interval?
electrolyte: hypocalcaemia, hypokalaemia, hypomagnesaemia acute myocardial infarction myocarditis hypothermia subarachnoid haemorrhage
What are the indications for cardioversion in VT?
If the patient has adverse signs (systolic BP < 90 mmHg, chest pain, heart failure) then immediate cardioversion is indicated.
In the absence of such signs antiarrhythmics may be used.
If these fail, then electrical cardioversion may be needed with synchronised DC shocks
What drug therapy is used in VT?
amiodarone: ideally administered through a central line
lidocaine: use with caution in severe left ventricular impairment
procainamide
Which drug should NOT be used in VT?
Verapamil
This is because Verapamil also blocks the calcium current responsible for sinus and AV nodal depolarization and can precipitate haemodynamic detoriaration, VF & cardiac arrest
What to do if drug therapy fails in VT?
electrophysiological study (EPS) implant able cardioverter-defibrillator (ICD) - this is particularly indicated in patients with significantly impaired LV function
What is the key step in management of peri-arrest tachycardias?
Following basic ABC assessment, patients are classified as being stable or unstable according to the presence of any adverse signs:
shock: hypotension (systolic blood pressure < 90 mmHg), pallor, sweating, cold, clammy extremities, confusion or impaired consciousness
syncope
myocardial ischaemia
heart failure
If there are adverse signs present in peri-arrest tachycardias what should be done?
synchronised DC shocks should be given
Treatment following this is given according to whether the QRS complex is narrow or broad and whether the rhythm is regular or irregular.
How do you treat regular broad-complex tachycardias in the context of peri-arrest?
stable/unstable -> shock?
assume ventricular tachycardia (unless previously confirmed SVT with bundle branch block)
loading dose of amiodarone followed by 24 hour infusion
How do you treat irregular broad-complex tachycardias in the context of peri-arrest?
stable/unstable -> shock?
- AF with bundle branch block - treat as for narrow complex tachycardia
- Polymorphic VT (e.g. Torsade de pointes) - IV magnesium
How do you treat regular narrow-complex tachycardias in the context of peri-arrest?
stable/unstable -> shock?
vagal manoeuvres followed by IV adenosine
if above unsuccessful consider diagnosis of atrial flutter and control rate (e.g. Beta-blockers)
How do you treat irregular narrow-complex tachycardias in the context of peri-arrest?
stable/unstable -> shock?
probable atrial fibrillation
if onset < 48 hr consider electrical or chemical cardioversion
rate control (e.g. Beta-blocker or digoxin) and anticoagulation
What are possible causes of palpitations?
arrhythmias
stress
increased awareness of normal heart beat / extrasystoles
What are first line investigations of palpitations?
12-lead ECG: this will only capture the heart rhythm for a few seconds and hence is likely to miss episodic arrhythmias. However, other abnormalities linked to the underlying arrhythmia (for example a prolonged QT interval or PR interval, or changes suggesting recent myocardial ischaemia) may be seen.
thyroid function tests: thyrotoxicosis may precipitate atrial fibrillation and other arrhythmias
urea and electrolytes: looking for disturbances such as a low potassium
full blood count
Palpitations presentation: What is the next step after first line investigations?
exclude an episode arrhythmia. Holter monitoring If no abnormality is found on the Holter monitor, and symptoms continue, other options include: external loop recorder implantable loop recorder
In atrioventricular (AV) block, or heart block, there is impaired electrical conduction between the atria and ventricles.
true
3 types
First-degree heart block?
PR interval > 0.2 seconds
asymptomatic first-degree heart block is relatively common and does not need treatment
What is Mobitz I/ Wenckebach
type 1 Second-degree heart block
progressive prolongation of the PR interval until a dropped beat occurs
What is mobitz II?
type 2 Second-degree heart block
PR interval is constant but the P wave is often not followed by a QRS complex
Third-degree (complete) heart block?
there is no association between the P waves and QRS complexes
What is Torsades De Pointes?
form of polymorphic ventricular tachycardia associated with a long QT interval. It may deteriorate into ventricular fibrillation and hence lead to sudden death.
How do you manage Torsades De Pointes?
IV magnesium sulphate
What is Wolff-Parkinson White?
syndrome is caused by a congenital accessory conducting pathway between the atria and ventricles leading to a atrioventricular re-entry tachycardia (AVRT). As the accessory pathway does not slow conduction AF can degenerate rapidly to VF
What are the ECG features of Wolff-Parkinson White?
short PR interval
wide QRS complexes with a slurred upstroke - ‘delta wave’
left axis deviation if right-sided accessory pathway*
right axis deviation if left-sided accessory pathway*
What are the two of Wolff-Parkinson White types
type A (left-sided pathway): dominant R wave in V1 type B (right-sided pathway): no dominant R wave in V1
What are the associations of WPW?
HOCM mitral valve prolapse Ebstein's anomaly thyrotoxicosis secundum ASD
What is the management of WPW?
definitive treatment: radiofrequency ablation of the accessory pathway
medical therapy: sotalol***, amiodarone, flecainide
sotalol should be avoided if there is coexistent atrial fibrillation as prolonging the refractory period at the AV node may increase the rate of transmission through the accessory pathway, increasing the ventricular rate and potentially deteriorating into ventricular fibrillation
in the majority of cases, or in a question without qualification, Wolff-Parkinson-White syndrome is associated with left axis deviation
true
The 2015 Resuscitation Council (UK) guidelines emphasise that the management of bradycardia depends on?
- identifying the presence of signs indicating haemodynamic compromise - ‘adverse signs’
- identifying the potential risk of asystole
In Peri-arrest rhythms: bradycardia
The following factors indicate haemodynamic compromise and hence the need for treatment?
shock: hypotension (systolic blood pressure < 90 mmHg), pallor, sweating, cold, clammy extremities, confusion or impaired consciousness
syncope
myocardial ischaemia
heart failure
What is the first line treatment of peri=arrest bradycardia with haemodynamic compromise?
Atropine (500mcg IV) is the first line treatment in this situation.
If there is an unsatisfactory response the following interventions may be used:
atropine, up to maximum of 3mg
transcutaneous pacing
isoprenaline/adrenaline infusion titrated to response
Specialist help should be sought for consideration of transvenous pacing if there is no response to the above measures.
What are the risk factors for asystole?
complete heart block with broad complex QRS
recent asystole
Mobitz type II AV block
ventricular pause > 3 seconds
(in peri-arrest bradycardia) if there is a satisfactory response to atropine specialist help is indicated to consider the need for transvenous pacing:
What are J waves and what are they associated with?
small bumps at the end of the QRS complex.
hypothermia
What are features of hypothermia?
bradycardia 'J' wave - small hump at the end of the QRS complex first degree heart block long QT interval atrial and ventricular arrhythmias
Delta waves are associated with ?
Wolff-Parkinson-White Syndrome
Saddle ST elevation is associated with?
pericarditis
