By Sasha Darwazeh FY1 Arrhythmias

Types of arrhythmias Site of abnormality: ● Supraventricular ● Ventricular Abnormalities of heart rate: ● Tachyarrhythmias ● Bradyarrhythmias

Tachyarrhythmias

Supraventricular Tachycardias:

Atrial Fibrillation 0.4% of population 2.4-4% >60 year olds, 4% >80 years olds. 50% of paroxysmal & 15-20% of chronic AF are idiopathic. 2º AF caused by dilatation, ↑ muscle mass, inflammation, infiltration & fibrosis. Generally associated with LA hypertrophy. Ineffective contractions = blood stasis in atria → thrombus formation. If from LA, can cause CVA; in RA can cause PE's. 3 types of AF: Acute AF - associated with systemic disease, precipated by electrolyte disturbance or hypoxia, resolves with treatment of underlying pathology Paroxysmal AF - recurrent episodes of AF lasting <48 hours which can progress to: Chronic AF - aka permanent AF.

Risk factors HTN Heart disease Lung disease Binge drinking Hyperthyroidism Carbon monoxide poisoning Clinical Features Early signs vague - fatigue & dyspnoea. Chronic phase- Irregular pulse (some impulses from atrial walls reach the ventricle, throwing it out of sinus rhythm). Force of contraction irregular Deteriorates with exercise Absent 'a' waves in JVP Thromboembolic events - CVA & PE.

Investigations ECG Chronic AF- ECG Paroxsysmal- 24h ECG. Bloods FBC U+Es TFTs Imaging CXR Echo - size of LA, LV function. Transoesophageal echo for assessment of thrombus formation.

Management Aim: return to SR. If not possible, control ventricular rate & thromboembolism risk Conservative Avoid alcohol & caffeine. Correct underlying pathologies - electrolyte disturbance, hypoxia. Medical Acute onset: If haemodynamicaly unstable → emergency cardioversion if life- threatening. IV amiodarone if not. Paroxysmal - treat only if symptomatic: Beta-blockers 1st-line BISOPROLOL Class Ic antiarrhythmics 2nd-line FLECAINIDE or SOTALOL

Chronic Rate-control <65; symptomatic; presenting 1st time; lone AF; or congestive heart failure. Digoxin + rate-limiting calcium-channel blocker i.e verapamil/diltiazem or digoxin + beta blocker. If fails pacemaker + ablation. Rhythm-control >65; coronary heart disease; contraindications to antiarrhythmics or elctrical cardioversion; no congestive heart failure. 1 st line chemical cardioversion- amiodarone. 2nd-line: flecainide/sotalol, amiodarone in structural heart disease. Thromboprophylaxis- CHADS-VASc. Warfarin - ↓ incidence of stroke by 70%. INR 2-3. Surgery Percutaneous radiofrequency ablation: catheter up femoral vein to heart with radiological guidance. Ablate abnormal tissue.

Never use verapamil & beta blocker together as can cause heart block & asystole Popular question in pharm exams!

Atrial flutter Atrial contraction rate > bpm. Re-entrant circuit of excitation- it goes straight back into the atria instead of impulses only travelling to ventricles. Causes: IHD, hyperthyroidism, cardiomyopathy & rheumatic heart, idiopathic. Clinical Features: Palpitations Chest pain SOB O/E: Regular, fast pulse 'A' waves in JVP exceeds pulse rate Carotid compression may slow rate Signs of heart failure

Investigations ECG: 3:1 block (3 atrial contractions: 1 ventricular contraction) → saw-tooth 2:1 block, P waves difficult to see. Carotid sinus pressure can uncouple atria & ventricles, revealing P waves. Consider in patients with a regular rate of 150 bpm. Blood: U+Es TFTs Imaging: Echo Management Drugs- antiarrhythmics: Class Ia - Disopyramide Class Ic - Flecanide, Propafenone Class III - Sotalol DC Cardioversion Pacing

Re entry SVT's Caused by 2 nd connection between atria & ventricles, in addition to normal conduction system. 2 types: ● AVRNT (Atrio-Ventricular Node Re-entry Tachycardia) - 2 nd connection closely related to AV node. ● AVRT (Atrio-Ventricular Re-entry Tachycardia) - 2 nd connection not related to AV node. Clinical Features: Palpitations Syncope/presyncope Chest pain & polyuria (release of ANP due to ↑ atrial pressures from contraction of atria against closed AV valve.) Symptoms often associated with exertion

Investigation: ECG Rate Narrow QRS complex P waves are inverted & one P wave per QRS complex. - masked by QRS complex (AVNRT) - or occur halfway between complexes (AVRT) Management Vagal - carotid sinus massage, valsalva manoeuvre, apply ice to face Drugs- adenosine/verapamil.(Or flecanide, sotalol) Electrical - pacing & cardioversion Ablation - burn away extra conduction pathway.

WPW aka pre-excitation syndrome Abnormal accessory pathway between atrium & ventricle. Rare → % of the population. Males> females, young people Predisposition to sudden death. Clinical Features: Mostly asymptomatic. Occasionally, palpitations/sudden death, general cardiac symptoms (SoB, dizziness or syncope) Investigations ECG: Delta wave PR interval <0.12s Management Ablation 1 st line in symptomatics If unstable - cardioversion Amiodarone/procainamide

Ventricular Tachyarrhythmias

Ventricular Fibrillation Ventricular muscle fibres contract randomly causing complete failure of ventricular function. Occurs in those with pre-existing disease i.e CHD. Risk Factors: CAD & MI VT which often precedes to VF Antiarrhythmic drug adminsitration Hypoxia Ischaemia AF Rapid rates in pre-excitation syndromes (e.g. WPW) Shock during cardioversion Electric shock Pacing to terminate VT Clinical Features MI → Chest pain, fatigue, palpitations

Investigations ECG: VF and If survive look for evidence of MI, WPW etc. Bloods ● Cardiac enzymes: troponin-T 12 hours after onset of symptoms ● U+Es: metabolic acidosis, hypokalaemia, hyperkalaemia, hypocalcaemia, hypomagnasaemia ● Drug levels of any antiarrhythmic, particularly digoxin ● Toxicology: cocaine can induce vasospasm ● TSH: hyperthyroidism CXR: signs of left heart failure, pulmonary hypertension Echo: check for structural deficiencies Angiography

Management of VF Shockable rhythm Check for response Check for pulse/ breathing for up to 10 seconds 2222 Head tilt/chin lift Get help Chest compressions 30:2 Attach monitor Assess rhythm Stand back & shock Continue compressions for 2 mins Adrenaline IV every 2-3 mins

VT Broad-complex tachycardia (QRS >120ms/3 small squares). Risk Factors: Structural heart disease/CHD Electrolyte disturbances: hypokalaemia, hypocalcaemia & hyponatraemia Clinical Features: Features of ischaemic heart disease or haemodynamic compromise. Chest pain, palpitations, dyspnoea, dizziness, syncope & symptoms of heart failure. Investigations ECG Bloods: U+Es: particularly calcium, potassium & magnesium. Levels of therapeutic drugs like digoxin Trop T for MI CXR -? heart failure

Management of VT ● Pulseless VT: treat using ALS ● Unstable VT: synchronised cardioversion- can result in VF! Amiodarone 1 st -line for haemodynamically unstable VT. Treat electrolyte disturbances. ● Stable VT: treat with IV lidocaine & cardioversion if lidocaine ineffective ● Refractory VT: amiodarone. ● Torsades de pointes (polymorphic VT) - ● Acute(acquired) – Stop QT prolonging drugs ?examples ● IV magnesium, then beta 1-adrenergic agonist (isoprenaline), temporary pacing ● Long-term - beta-blockers (congenital), pacing

Bradycardias

Heart Block 1 st degree heart block - PR interval > 0.2s; no dropped QRS complex 2 nd -degree heart block Type 1 (Mobitz I/Wenkebach) - PR interval ↑ with each beat until you get a dropped QRS complex Type 2 (Mobitz II) - intermittent failure of P waves to conduct, not preceded by P wave elongation 2:1 & 3:1 type - regularly dropped QRS complexes with a 2:1 or 3:1 ratio 3 rd -degree heart block (complete heart block) - P waves never conduct & are unrelated on ECG Causes: usually CAD, inferior or anterior wall MI.

Management 1 st degree - no treatment 2 nd degree – pacemaker if consciousness is affected. 3 rd -degree – pacemaker Atropine can be used if symptomatic If patient has heart block, they need to avoid: ● Anti-arrhythmics - amiodarone, flecainide. ● Beta blockers - such as atenolol, bisoprolol, propanolol. ● Calcium channel blockers - such as verapamil, diltiazem.

Bundle branch block Delay of electrical conduction down either the left of right bundle branch. LBBB: aortic stenosis, dilated cardiomyopathy, MI, CAD. RBBB: atrial septal defect, PE, MI ECG Changes WiLLiaM & MaRRoW Wide QRS complexes. LBBB: there is a W shape in V1 and an M shape in V6. RBBB: there is an M shape in V1 and a W shape in V6 Management Generally nothing but if bundle branch block is severe, needs pacemaker