Arrhythmias

• Atrial flutter gives a sawtooth appearance on the ECG, with repeated P wave occurring at around 300 per minute, with a narrow complex tachycardia.

  Seen best in lead V1
• Although people with atrial flutter often have no symptoms, symptoms can include:

  • palpitations
  • shortness of breath
  • fatigue
  • syncope
  • chest pain
• Treatment for atrial flutter:

  • beta-blocker or calcium channel blocker
  • an intravenous beta-blocker or verapamil hydrochloride is preferred for rapid control.
• If a patient with atrial flutter is haemodynamically unstable then direct current cardioversion is used
• Catheter ablation can stop the re-entry path in atrial flutter. Patients should be anticoagulated for at least 3 weeks
• patients with atrial flutter should be offered anticoagulation based on the CHA2DS2-VASc score.
• Paroxysmal SVT often terminates spontaneously or with:

  • valsalva manoeuvre
  • putting face in ice cold water
  • carotid sinus massage
• If manoeuvres for SVT do not work or patient has severe symptoms, administer IV adenosine. If this does not work it suggests the arrhythmia is of atrial origin such as AF
• Haemodynamically unstable patients with SVT need direct current cardio version
• Patients with recurrent SVT can be treated with catheter ablation. SVT can be prevented with beta blockers and calcium channel blockers
• Ventricular tachycardia is commonly due to scarring post MI
• Pulseless VT is a shockable cardiac arrest rhythm
• most patients with VT receive a pacemaker. It can be managed with beta blockers and/or amiodarone
• Ventricular fibrillation causes no coordinated electrical activity on an ECG. There is a chaotic fibrillating baseline. This is incompatible with life and leads to cardiac arrest
• Patients in VF require defibrillation and amiodarone. They can have an internal defibrillator implanted.
• Inappropriate sinus tachycardia is where there is no underlying pathology causing the tachycardia. Eliminate triggers. Can be treated with ivabridine, beta blockers and calcium channel blockers
• Patients with bradycardia that are unstable and at risk of asystole should receive IV atropine and inotropes (adrenaline)
• Atrial Fibrillation is a type of SVT that causes the atria to fibrillate. This causes an irregularly irregular pulse. Blood can stagnate in the atria leading to an increased risk of clot formation.
• Atrial Fibrillation causes irregularly irregular ventricular contraction. This leads to impaired filling during systole - therefore patients are at risk of heart failure
• Patients with atrial fibrillation are often asymptomatic, but can present with:

  • Palpitations
  • SOB
  • Pre-syncope / syncope
  • Symptoms of associated conditions such as stroke and sepsis
• Common causes of AF can be remembered as SMITH:

  • S - Sepsis
  • M - mitral valve pathology
  • I - ischaemic heart disease
  • T - thyrotoxicosis
  • H - Hypertension

  Other causes include PE, alcohol and caffeine
• Types of atrial fibrillation:

  • Paroxysmal - brief event that may go away on its own. Often tachy-brady syndrome
  • Persistent - lasts more than a week, could still terminate with no treatment
  • Long term persistent - more than a year
  • Permanent - does not terminate even with medication due to remodelling and damage to the circuit
• Atrial fibrillation on an ECG will show:

  • Absent P waves
  • Irregular and narrow QRS complexes

  24hr tape may be needed to diagnose paroxysmal AF
• Bloods for AF: U&Es, TFTs and cardiac enzymes
• Consider an echo for patients with AF to look for:

  • Left atrial enlargement and hypertrophy
  • Mitral valve disease
  • Poor LV function - heart failure
• All patients with AF will receive rate control and anticoagulation. Rhythm control is indicated when:

  • Reversible cause
  • new onset <48 hours
  • Heart failure caused by AF
  • Persistent symptoms
• First line rate control in AF is beta blockers

  Target is to keep heart rate below 100 so time is extended for ventricles to fill with blood

  Rate limiting calcium channel blockers can also be used but they are contraindicated in heart failure

  Digoxin if persistent symptoms but monitor for toxicity
• Amiodarone is an anti-arrhythmic that can be used in heart failure patients for long term control of atrial fibrillation
• Rhythm control can be done pharmacologically or electrically

  • Pharmacological cardioversion - flecainide and propafenone
  • Electrical cardioversion - immediate if patient unstable or delay and anti-coagulate patient for at least 3 weeks
• First line anticoagulation for AF is DOACs such as rivaroxaban and apixaban

  Give warfarin if DOACs contraindicated

  If patient acutely unwell give heparin
• DOACs shouldn't be given to patients with mechanical valves due to increased risk of thromboembolism and bleeding
• CHA2DS2-VASc score is used to calculate stroke risk in patients with AF and decide if they need anti-coagulation:

  • 0 - no anticoagulation
  • 1 - consider anticoagulation in men
  • 2 - offer anticoagulation
• ORBIT score is used to calculate the risk of major bleed in patients on anticoagulation with AF
• Torsades de pointes:

  • Consequence of prolonged QT interval
  • Will terminate spontaneously and revert to sinus rhythm or progress to VT
• Causes of prolonged QT:

  • Long QT syndrome (inherited)
  • Medications - macrolide antibiotics (clarithromycin) and amiodarone
  • Electrolyte imbalances - hypokalaemia, hypomagnesaemia and hypocalcaemia
• Medications that prolong QT:

  • Antipsychotics
  • Citalopram
  • flecainide
  • Sotalol
  • Amiodarone
  • Macrolide antibiotics - Azithromycin, clarithromycin and erythromycin
• Acute management of torsades de pointes:

  • Correct underlying cause
  • Magnesium infusion
  • Defibrillation if ventricular tachycardia occurs
• Wolff-parkinson-white syndrome:

  • Preexcitation syndrome - double excitation of ventricles
  • Congenital accessory pathway - Bundle of Kent
  • Short PR interval and delta wave (early slurred upstroke in the QRS)
  • Main concern is development of AF
  • During symptomatic episode - same treatment as SVT
  • Amiodarone
  • Catheter ablation
  • Avoid AV node blockers
• AV node blocking drugs:

  • Adenosine
  • Calcium channel blockers
  • Beta blockers
  • Digoxin
• Macrolide antibiotics e.g. erythromycin can cause QT prolongation - Torsades de pointes