Arryhthmias: Atrial flutter Flashcards
What is atrial flutter?
Atrial flutter is a form of supraventricular tachycardia characterised by a succession of rapid atrial depolarisation waves.
What are the ECG findings in atrial flutter?
‘Sawtooth’ appearance; the underlying atrial rate is often around 300/min, and the ventricular rate depends on the degree of AV block.
What happens to the ventricular rate with a 2:1 AV block in atrial flutter?
The ventricular rate will be 150/min.
When may flutter waves be visible?
Flutter waves may be visible following carotid sinus massage or adenosine.
How is the management of atrial flutter similar to atrial fibrillation?
Management is similar, although medication may be less effective.
How does atrial flutter respond to cardioversion?
Atrial flutter is more sensitive to cardioversion, allowing for lower energy levels to be used.
What is a curative treatment for most patients with atrial flutter?
Radiofrequency ablation of the tricuspid valve isthmus.
What is atrioventricular (AV) block?
AV block, or heart block, is impaired electrical conduction between the atria and ventricles.
What are the types of atrioventricular block?
There are three types: First-degree heart block, Second-degree heart block, and Third-degree heart block.
What characterizes first-degree heart block?
In first-degree heart block, the PR interval is greater than 0.2 seconds.
Asymptomatic first-degree heart block is relatively common and does not need treatment.
What are the types of second-degree heart block?
Second-degree heart block has two types: Type 1 (Mobitz I, Wenckebach) and Type 2 (Mobitz II).
What is type 1 second-degree heart block?
Type 1 (Mobitz I, Wenckebach) involves progressive prolongation of the PR interval until a dropped beat occurs.
What is type 2 second-degree heart block?
Type 2 (Mobitz II) has a constant PR interval, but the P wave is often not followed by a QRS complex.
What characterizes third-degree heart block?
In third-degree (complete) heart block, there is no association between the P waves and QRS complexes.
What are features suggesting VT rather than SVT with aberrant conduction?
AV dissociation, fusion or capture beats, positive QRS concordance in chest leads, marked left axis deviation, history of IHD, lack of response to adenosine or carotid sinus massage, QRS > 160 ms
What is AV dissociation?
A condition where the atria and ventricles beat independently.
What are fusion or capture beats?
Fusion beats occur when a normal heartbeat merges with a ventricular tachycardia beat, while capture beats occur when a normal impulse captures the ventricle during tachycardia.
What does positive QRS concordance in chest leads indicate?
It suggests that all QRS complexes in the chest leads are in the same direction.
What does marked left axis deviation indicate?
It suggests a significant change in the heart’s electrical axis, often associated with ventricular tachycardia.
What is the significance of a history of IHD?
It indicates a higher risk for ventricular tachycardia due to underlying heart disease.
What does lack of response to adenosine or carotid sinus massage suggest?
It suggests that the tachycardia is likely ventricular rather than supraventricular.
What is the significance of a QRS duration greater than 160 ms?
It is a criterion that supports the diagnosis of ventricular tachycardia.
What are the features of complete heart block?
Syncope, heart failure, regular bradycardia (30-50 bpm), wide pulse pressure, JVP: cannon waves in neck, variable intensity of S1.
What is first degree heart block?
PR interval > 0.2 seconds.
What is second degree heart block type 1?
Progressive prolongation of the PR interval until a dropped beat occurs.
Also known as Mobitz I or Wenckebach.
What is second degree heart block type 2?
PR interval is constant but the P wave is often not followed by a QRS complex.
Also known as Mobitz II.
What is third degree (complete) heart block?
There is no association between the P waves and QRS complexes.
What is bradycardia?
Bradycardia is a slower than normal heart rate.
What does the management of bradycardia depend on?
The management of bradycardia depends on identifying adverse signs and the potential risk of asystole.
What are adverse signs indicating haemodynamic compromise?
Adverse signs include shock (hypotension, pallor, sweating, cold clammy extremities, confusion), syncope, myocardial ischaemia, and heart failure.
What is the first line treatment for bradycardia?
Atropine (500mcg IV) is the first line treatment.
What interventions may be used if there is an unsatisfactory response to atropine?
Interventions may include atropine (up to 3mg), transcutaneous pacing, or isoprenaline/adrenaline infusion titrated to response.
When should specialist help be sought in bradycardia management?
Specialist help should be sought for consideration of transvenous pacing if there is no response to initial measures.
What are the risk factors for asystole?
Risk factors for asystole include complete heart block with broad complex QRS, recent asystole, Mobitz type II AV block, and ventricular pause > 3 seconds.
When is specialist help indicated even with a satisfactory response to atropine?
Specialist help is indicated to consider the need for transvenous pacing in certain risk factors for asystole.
What is tachycardia?
Tachycardia refers to a rapid heart rate, typically defined as a resting heart rate of over 100 beats per minute.
What did the 2015 Resuscitation Council (UK) guidelines change regarding tachycardia management?
The guidelines replaced separate algorithms for broad-complex tachycardia, narrow complex tachycardia, and atrial fibrillation with one unified treatment algorithm.
How are patients classified in the management of peri-arrest tachycardias?
Patients are classified as stable or unstable based on the presence of adverse signs.
What are the adverse signs indicating an unstable patient?
Adverse signs include shock (hypotension, pallor, sweating, cold clammy extremities, confusion), syncope, myocardial ischaemia, and heart failure.
What should be done if any adverse signs are present?
Synchronised DC shocks should be given, with up to 3 shocks allowed before seeking expert help.
What is the treatment for regular broad-complex tachycardia?
Assume ventricular tachycardia and administer a loading dose of amiodarone followed by a 24-hour infusion.
What should be done for irregular broad-complex tachycardia?
Seek expert help; possibilities include atrial fibrillation with bundle branch block or torsade de pointes.
What is the treatment for regular narrow-complex tachycardia?
Perform vagal manoeuvres followed by IV adenosine; if unsuccessful, consider atrial flutter and control the rate.
What is the approach for irregular narrow-complex tachycardia?
It is likely atrial fibrillation; if onset is < 48 hours, consider electrical or chemical cardioversion.
What is usually the first-line treatment for rate control in irregular narrow-complex tachycardia?
Beta-blockers are usually the first-line treatment unless contraindicated.
What is the definition of supraventricular tachycardia (SVT)?
SVT refers to any tachycardia that is not ventricular in origin, typically used in the context of paroxysmal SVT.
What characterizes episodes of paroxysmal SVT?
Episodes are characterized by the sudden onset of a narrow complex tachycardia, typically an atrioventricular nodal re-entry tachycardia (AVNRT).
What are other causes of supraventricular tachycardia?
Other causes include atrioventricular re-entry tachycardias (AVRT) and junctional tachycardias.
What are the acute management options for SVT?
Acute management options include vagal manoeuvres, intravenous adenosine, and electrical cardioversion.
What is the Valsalva manoeuvre?
The Valsalva manoeuvre involves trying to blow into an empty plastic syringe.
What is the dosing protocol for intravenous adenosine in SVT management?
Administer a rapid IV bolus of 6mg; if unsuccessful, give 12 mg; if still unsuccessful, give a further 18 mg.
What is contraindicated in asthmatics during SVT management?
Intravenous adenosine is contraindicated in asthmatics; verapamil is a preferable option.
What are the prevention strategies for SVT episodes?
Prevention strategies include beta-blockers and radio-frequency ablation.
What is Torsades de pointes?
A form of polymorphic ventricular tachycardia associated with a long QT interval. It may deteriorate into ventricular fibrillation and lead to sudden death.
What are some congenital causes of long QT interval?
Jervell-Lange-Nielsen syndrome and Romano-Ward syndrome.
Which antiarrhythmics can cause a long QT interval?
Amiodarone, sotalol, and class 1a antiarrhythmic drugs.
What medications can lead to a long QT interval?
Tricyclic antidepressants, antipsychotics, chloroquine, terfenadine, and erythromycin.
What electrolyte imbalances can cause a long QT interval?
Hypocalcaemia, hypokalaemia, and hypomagnesaemia.
What are other causes of long QT interval?
Myocarditis, hypothermia, and subarachnoid haemorrhage.
What is the management for Torsades de pointes?
IV magnesium sulphate.
What is ventricular tachycardia (VT)?
Ventricular tachycardia (VT) is 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 ventricular tachycardia (VT)?
The two main types of VT are monomorphic VT and polymorphic VT.
What commonly causes monomorphic VT?
Monomorphic VT is most commonly caused by myocardial infarction.
What is a subtype of polymorphic VT?
A subtype of polymorphic VT is torsades de pointes, which is precipitated by prolongation of the QT interval.
What are the causes of a prolonged QT interval?
Causes of a prolonged QT interval include congenital factors, drugs, and other conditions.
What are some congenital causes of prolonged QT interval?
Congenital causes include Jervell-Lange-Nielsen syndrome (includes deafness) and Romano-Ward syndrome (no deafness).
What drugs can cause prolonged QT interval?
Drugs that can cause prolonged QT interval include amiodarone, sotalol, class 1a antiarrhythmic drugs, tricyclic antidepressants, fluoxetine, chloroquine, terfenadine, and erythromycin.
What are some other causes of prolonged QT interval?
Other causes include electrolyte imbalances (hypocalcaemia, hypokalaemia, hypomagnesaemia), acute myocardial infarction, myocarditis, hypothermia, and subarachnoid haemorrhage.
What is the management for VT with adverse signs?
If the patient has adverse signs (systolic BP < 90 mmHg, chest pain, heart failure), then immediate cardioversion is indicated.
What is the management for VT without adverse signs?
In the absence of adverse signs, antiarrhythmics may be used. If these fail, then electrical cardioversion may be needed with synchronised DC shocks.
What are the drug therapies for VT?
Drug therapies include amiodarone (ideally through a central line), lidocaine (use with caution in severe left ventricular impairment), and procainamide.
What should NOT be used in VT?
Verapamil should NOT be used in VT.
What to do if drug therapy fails in VT?
If drug therapy fails, options include electrophysiological study (EPS) and implantable cardioverter-defibrillator (ICD), particularly indicated in patients with significantly impaired LV function.
What does the European Resuscitation Council advise regarding broad complex tachycardia in a peri-arrest situation?
It is assumed to be ventricular in origin.
What signs indicate that immediate cardioversion is needed?
Adverse signs include systolic BP < 90 mmHg, chest pain, heart failure, and syncope.
What should be used if adverse signs are absent?
Antiarrhythmics may be used.
What is the next step if antiarrhythmics fail?
Electrical cardioversion may be needed with synchronised DC shocks.
What is the preferred method for administering amiodarone?
Ideally administered through a central line.
What caution should be taken with lidocaine?
Use with caution in severe left ventricular impairment.
Which drug should NOT be used in ventricular tachycardia (VT)?
Verapamil should NOT be used in VT.
What are the options if drug therapy fails?
Options include electrophysiological study (EPS) and implantable cardioverter-defibrillator (ICD).
In which patients is an implantable cardioverter-defibrillator (ICD) particularly indicated?
Patients with significantly impaired left ventricular function.
