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Arrhythmias Case 12 By Mariam RaufCase 12 Conduction System ECG ArrhythmiaElectrical Conduction SystemConduction System Nervous System Sympathetic Nervous System: - Increases heart rate and force of contraction - Stimulates the SAN, AVN and myocardium during a sympathetic response Parasympathetic Nervous System: - Decreases heart rate - Primarily affects the SA node and AV noce via the vagus nerve, and promotes the parasympathetic response Pacemaker Action Potential Na Funny current channels (HCN) and T-types Ca2+ channels bring the resting potential to threshold potential Voltage-gated L-type Ca2+ channels open leading to rapid depolarisation After peak, depolarisation L-type Ca2+ channels close and voltage-gated K+ channels open repolarise the cell Na+/K+ ATPase pump maintains resting membrane potential (pacemaker potential)Ventricular Action Potential When a neighbouring cell becomes depolarised, Ca2+ and Na+ ions enter the cardiomyocyte through gap junctions causing slight depolarisation Once this reaches a threshold potential (-70mV) voltage-gated Na+ channels open. This leads to rapid depolarisation. At peak depolarisation (+20mV) voltage-gated Na+ channels open and voltage-gated K+ channels & L-Type Ca2+ channels open. The K+ channels open slightly earlier than the Ca2+ channels so there is slight repolarization Plateau is maintained by K+ channels & L-type Ca2+ moving ions in opposite directions. This allows time for the sarcoplasmic reticulum to release Ca2+ for muscle contraction L-type Ca2+ close and Ca2+ is reabsorbed into SER, while voltage gated K+ channels remain open causing repolarisationECG Question 1 A Left Arm You are placed, you are asked to place the ECG leads on a B Left Mid-axillary line, 5th intercostal space female patient. You think back to your PreClinEazy revision C Left Midclavicular line, 5th intercostal space session. Where is the V4 lead placed? D Right Arm E Right Sternal edge, 2nd intercostal space Question 1 A Left Arm You are placed, you are asked to place the ECG leads on a B Left Mid-axillary line, 5th intercostal space female patient. You think back to your PreClinEazy revision C Left Midclavicular line, 5th intercostal space session. Where is the V4 lead placed? D Right Arm E Right Sternal edge, 2nd intercostal space ECG Leads RIDE YOUR GREEN BIKE V1: Right Sternal Edge, 4th IC Space Limb Leads: V2: Left Sternal Edge, 4th IC Space - Right Arm (RA) Red Lead V3: Midclavicular line, 5th IC Space - Left Arm (LA) Yellow Lead V4: Halfway between V2 & V4 - Left Leg (LL) Green Lead V5: Left Anterior Axillary line, 5th IC Space - Right Leg (RL) Black Lead V6: Left Mid-Axillary line, 5th IC Space Question 2 You are presented with a 64-year-old A Left Circumflex male who collapsed while at a restaurant complaining a severe B Left Marginal Artery chest pain. You diagnose an inferior STEMI. You know that the coronary C Posterior Descending Artery artery that is occluded also supplies the Sinoatrial Node. D Right Circumflex Which coronary artery is occluded? E Right Coronary Artery Question 2 A Left Circumflex You are presented with a 64-year-old male who collapsed while at a restaurant B Left Marginal Artery complaining a severe chest pain. You diagnose an inferior STEMI. C Posterior Descending Artery You know that the coronary artery that is occluded also D Right Circumflex supplies the Sinoatrial Node. Which coronary artery is E Right Coronary Artery occluded? - 1 small square = 0.04s ECG T erritories - Length of paper = 10sHow to read ECGs Rate Rhythm P wave & PR interval - Number of QRS x 6 - Regular or Irregular? - P wave morphology - 300/number of big squares - Sinus? - PR segment: short, long or between R-R interval - P wave before QRS complex depressed - Normal = 60-100 bpm - Normal PR interval: 3-5 small - Tachycardia >100 bpm squares - Bradycardia <60 bpm T wave & QT interval ST Segment QRS Complex - QT prolongation - Elevated or Depressed? - Wide or narrow? - T wave: peaked, - Normal <120 ms hyperacute, inverted or - Special morphology: biphasic WilliaM MarroW - U wave?Arrhythmias Sinus Rhythm Arrhythmias - Any cardiac rhythm in which - A disturbance to the normal cardiac depolarisation of the cardiac muscle rhythm and rate (60-100 bpm) begins at SA node - Tachyarrhythmia: HR >100 bpm + - Each P wave is followed by QRS abnormal cardiac rhythm complex - Bradycardia: HR <60 bpm + abnormal - PR interval = 120-200 ms cardiac rhythm - Regular rhythmBradyarrhythmia BRADYARRHYTHMIA NARROW QRS <120ms BROAD QRS >120ms SINUS BRADYCARDIA AV NODE BLOCK BUNDLE BRANCH BLOCKHeart Block 1st Degree HB 2nd Degree HB 3rd Degree HB - Pathophysiology: - Pathophysiology: - Pathophysiology: Slowed AVN conduction Intermittent conduction between atria Complete lack of conduction + ventricles between atria & ventricles - Causes: AV node blocking drugs - Causes: - Causes: High Vagal tone Ischaemia, AV node blocking drugs RCA occlusion (supplying - Symptoms: SAN & AVN), inferior MI, - Symptoms: Bradycardia, dyspnoea, syncope, Asymptomatic AVN blocking drugs, cardiac regularly irregular pulse surgery - ECG Findings: - ECG Findings: - Symptoms: Prolonged sinus rhythm BUT Mobitz type 1: Severe bradycardia, SOB, prolonged PR interval Progressive PR interval lengthening syncope, heart failure (>200ms until a QRS drops - ECG Findings: No Mobitz type 2: Constant PR interval BUT regular or association between p wave & QRS irregular dropped QRS complex TREATMENT: Heart Blocks Stop any causative agents + monitor degree need 3rd If the R is far from , PACEMAKER then you have a FIRST DEGREE Longer , longer, longer, drop! Then you have a WENKEBACH If some Ps don’t through, then you have MOBITZ II If Ps and Qs don’t agree, then you have a THIRD DEGREE Left Bundle Branch Block V6 WiLLiaM V1 V1 MaRRoW V6 Right Bundle Branch Block Question 3 A Atrial Flutter A 5-year-old child is brought in by their mother following an accident at school. Alongside the Atrial Fibrillation wound being cleaned and treated (using B aseptic wound care techniques ofc), it is found that the child heart is abnormal. When the C Supraventricular Arrhythmia child takes a deep breath in their HR increases and taking a deep breath out causes HR to Sinus Arrhythmia decreases. D What is the phenomena known as? E Ventricular Fibrillation Question 3 A Atrial Flutter A 5-year-old child is brought in by their mother following an accident at school. Alongside the Atrial Fibrillation wound being cleaned and treated (using B aseptic wound care techniques ofc), it is found that the child heart is abnormal. When the C Supraventricular Arrhythmia child takes a deep breath in their HR increases and taking a deep breath out causes HR to Sinus Arrhythmia decreases. D What is the phenomena known as? E Ventricular FibrillationTachyarrhythmia TACHYCARDIA BROAD QRS NARROW QRS REGULAR IRREGULAR IRREGULAR REGULAR POLYMORPHIC VENTRICULAR ATRIAL FLUTTER ATRIAL FIBRILLATION TACHYCARDIA VENTRICULAR TACHYCARDIA VENTRICULAR SVT (AVRT/AVNRT) FIBRILLATION A TRIAL FLUTTER WHAT IS IT? SIGNS + SYMPTOMS - Palpitations - Supraventricular tachycardia - Chest pain - Rapid atrial depolarisation waves - Fatigue - Small reentrant circuit in right atrium - Lightheadedness repeatedly conduct atrial impulses to AVN - SOB - Tachycardia (can present with 2:1 block) DIAGNOSIS TREATMENT ECG: 1. Rate control = Beta and calcium blockers - Typical Sawtooth Pattern 2. Rhythm control = Digoxin If hemodynamically unstable: DC - Narrow QRS cardioversion+anticoagulation A TRIAL FIBRILLA TION WHAT IS IT? SIGNS + SYMPTOMS Paroxysmal: recurrent episodes (>30s in duration) that - Asymptomatic terminate spontaneously or with intervention within 7 - Palpitations days - Chest pain Persistent: AF that fails to self-terminate within 7 days. If - Dyspnoea lasts >12 months known as ‘long-standing persistent AF’ Permanent: sinus rhythm cannot be restored or - Syncope maintained ans AF is the accepted final rhythm - Thromboembolic events (Stroke) DIAGNOSIS TREATMENT ECG: RATE CONTROL: RHYTHM CONTROL: - Irregularly irregular rhythm 1. Beta Blockers 1. Na+ Channel - Absence of P waves (no coordinated atrial 2. Ca2+ Channel Blockers activity) Blockers 2. Amiodarone - Irregular, fibrillating baseline 3. Digoxin 3. Electrical conduction Don’t give Beta-blockers with Ca2+ JVP: Absent ‘a’ wave on JVP channel bblockrs due to risk of heart Question 4 A Add Apixaban A 70-year-old man is attending the cardiology clinic for a review of his Add Furosemide medication for his atrial fibrillation. His blood B pressure reading in clinic today was 150/95 mmHg. You notice he has bilateral pitting C Add Spironolactone oedema. He has no history of a stroke or TIA. His current medications include: D Add Ramipril Atorvastatin, Digoxin, Ramipril & Metformin. What is the most appropriate next stage of E D/C cardioversion + heparin managing his atrial fibrillation? Question 4 A Add Apixaban A 70-year-old man is attending the cardiology clinic for a review of his Add Furosemide medication for his atrial fibrillation. His blood B pressure reading in clinic today was 150/95 mmHg. You notice he has bilateral pitting C Add Spironolactone oedema. He has no history of a stroke or TIA. His current medications include: D Add Ramipril Atorvastatin, Digoxin, Ramipril & Metformin. What is the most appropriate next stage of E D/C cardioversion + heparin managing his atrial fibrillation? - DOAC e.g. apixaban factor Xa inhibitor Use CHADsVASC to calculate the need for an long term anticoagulant, if greater than >1 in men or >2 in females = give DOAC AF + ANTICO AGULATION - 3 weeks anticoagulation prior to cardioversion - Non-pharmacological management: 1. Radiofrequency catheter ablation 2. Pulmonary vein isolation 3. Implantable cardiac defibrillator - Hemodynamically unstable: DC cardioversion + Heparin SUPRA VENTRICULAR TACHYCARDIA WHAT IS IT? SIGNS + SYMPTOMS - Palpitations - AVRT: Reentrant circuit across atria + - Lightheadedness - Dyspnea ventricles - Syncope - AVNRT: Reentrant circuit within AV node - Chest pain - Tachycardia DIAGNOSIS TREATMENT 1. Valsalva manoeuvre: e.g. trying to blow into an ECG: - Narrow QRS empty plastic syringe - Absent P waves 2. IV adenosine (6mg -> 12mg -> 18mg) contraindicated in asthmatics - verapamil is preferred 3. Electrical conduction Question 5 A Alpha wave A 24-year-old women attends the GP for some routine checks. She explains she is fit Delta wave and well but explained she has been getting B some intermittent palpitations for the past few months. The GP decides to do an ECG to C Gamma wave rule out anything serious. From the ECG, the GP diagnoses Wolff-Parkinson- White D J wave Syndrome. What wave is clinical to WPW syndrome E U wave Question 5 A Alpha wave A 24-year-old women attends the GP for some routine checks. She explains she is fit Delta wave and well but explained she has been getting B some intermittent palpitations for the past few months. The GP decides to do an ECG to C Gamma wave rule out anything serious. From the ECG, the GP diagnoses Wolff-Parkinson- White D J wave Syndrome. What wave is clinical to WPW syndrome E U wave WOLF P ARKINSON WHITE WHAT IS IT? RISK - Its a type/subset of AVRT - Extra conduction pathway between atria If the fast atria arrhythmia transmits to the ventricles: and ventricles AF -> VF can lead to cardiac arrest - BUNDLE OF KENT (Bypasses AVN) DIAGNOSIS TREATMENT ECG: Radiofrequency ablation of Bundle of 1. Slurred QR upstroke -> Delta wave Kent pathway 2. Short PR interval -> reduced AVN delay VENTRICULAR T ACHYCARDIA WHAT IS IT? SIGNS + SYMPTOMS - Palpitations Ventricular tachycardia occurs due to rapid, - Lightheadedness recurrent ventricular depolarisation from a focus - Chest pain within ventricles. This commonly due to scarring of - Fatigue the ventricles following myocardial infarction - Tachycardia - Signs of heart failure DIAGNOSIS TREATMENT 1. Rate Control: Amiodarone 2. Rhythm Control: Flecainide Rapid, broad-complex tachycardia (QRS >120ms) 3. Maintenance: Beta Blockers 4. Implantable cardiac defibrillator POLYMORPHIC VENTRICULAR TACHYCARDIA WHAT IS IT? SIGNS + SYMPTOMS - Palpitations A type of ventricular tachycardia in - Dizziness which have QRS complex that vary in - SOB shape, size and axis e.g. torsades de - Syncope pointes - Cardiac Arrest DIAGNOSIS TREATMENT ECG: Ventricular tachycardia that ‘twists’ around the isoelectric line. This IV Magnesium Sulphate subtype occurs secondary to a prolonged QT interval VENTRICULAR FIBRILLA TION WHAT IS IT? SIGNS + SYMPTOMS Life-threatening cardiac arrhythmia - Sudden loss of consciousness characterized by chaotic, disorganized - Absent pulse electrical activity in the ventricles, which causes the heart to quiver rather than - Apnea (no breathing) - Cardiac Arrest contract effectively. TREATMENT DIAGNOSIS ECG: - Defibrillation Chaotic, disorganized, and irregular - CPR and epinephrine pattern without discernible P waves, QRS complexes, or T waves. - Amiodarone REFERENCES • https://www.saem.org/about-saem/academies-interest-groups-affiliates2/cdem/for-students/online-e ducation/m3-curriculum/group-electrocardiogram-%28ecg%29-rhythm-recognition/stemiPLEASE FILL OUT THE FEEDBACK FORM PLEASE TUNE IN TO OUR REMAINING SESSIONS THIS WEEK osceazyofficial OSCEazy osceazy@gmail.com OSCEazy osceazyofficial