ECG Masterclass PDF

ECG Masterclass Paramedic Science  Learning Outcomes Overview of the Heart The Electrical Conduction System Lead Placement Lead Views How to read an ECG 32 ECG Arrythmia's The Heart The Heart The Electrical Conduction System  The Electrical Conduction Sy...

ECG Masterclass Paramedic Science  Learning Outcomes Overview of the Heart The Electrical Conduction System Lead Placement Lead Views How to read an ECG 32 ECG Arrythmia's The Heart The Heart The Electrical Conduction System  The Electrical Conduction System The Sinoatrial Node (SA) has an intrinsic Firing rate of 80 -110 bpm However, the vagus nerve stimulates the SA node and this reduces the rate to 60 – 80 bpm as a result of vagal tone. The Atrioventricular Node (AV) node has an intrinsic firing rate of 40-60 bpm Purkinje Fibres have an intrinsic firing rate of 20-40 bpm Lead Placement  Lead Placement Dextrocardia Dextrocardia is a rare congenital heart condition in which your heart is in the right side of your chest and points to the right. Typically, your heart is on your left side and points to the left. Dextrocardia only needs treatment if other heart issues or genetic syndromes are causing problems. Lead Placement Eindhoven's Triangle Polarity  What is in a beat? P Wave Atrial Depolarisation PR Segment Delay at AV Node QRS Segment Ventricular Depolarisation T Wave Ventricular Repolarisation Isoelectric Line No Electrical Activity  ECG Printer P-R Interval 0.12 to 0.20sec Q-T Interval 0.35 to 0.44 sec S-T Segment 0.05 to 0.15 sec QRS Interval 0.06 to 0.11 sec ECG Printer 1 small square = 0.04 seconds 5 small squares = 1 Large Square 1 Large Square = 0.2 seconds 5 Large squares = 1 second  Steps for Reading an ECG Is there a P Wave? Is there a P wave before every QRS? Is the PR Interval Normal? Is there a QRS? Is the QRS Complex normal? What is the QRS Interval? Is there a T wave? What is the ST Interval? Is ST Segment Normal? What is the Rate? What is the Rhythm?  Normal Sinus Rhythm Rate: 60-100 bpm Regularity: Regular P Wave: Present P:QRS Ratio: 1:1 PR Interval: Normal QRS Width: Normal  Sinus Tachycardia Rate: Greater than 100bpm Regularity: Regular P Wave: Present P:QRS Ratio: 1:1 PR Interval: Slightly Prolonged QRS Width: Slightly Prolonged  Sinus Bradycardia Rate: Less than 60bpm Regularity: Regular P Wave: Present P:QRS Ratio: 1:1 PR Interval: Slightly Prolonged QRS Width: Slightly Prolonged  Sinus Pause (AKA Ventricular Standstill) Rate: Varies Regularity: Irregular P Wave Present except during pauses P:QRS Ratio: 1:1 PR Interval: Normal QRS Width: Normal Atrial Fibrillation Rate: Variable Ventricular Response Regularity: Irregularly Irregular P Wave: None, disorganised activity P:QRS Ratio: None PR Interval: None QRS Width: Normal Supraventricular Tachycardia Rate: >100 bpm Regularity: Regular P Wave: Normal but lost in prior T wave depending on rate P:QRS Ratio: 1:1 if P wave visible PR Interval: Variable QRS Width: Varies, usually narrows QRS  1st Degree AV Block Rate: Depends on Rhythm Regularity: Regular P Wave: Normal P:QRS Ratio: 1:1 PR Interval: Prolonged >0.20 sec QRS Width: Normal 2nd Degree (Type 1) AV Block (Wenckebach) Rate: Depends on Rhythm Regularity: Regularly Irregular P Wave: Present P:QRS Ratio: Variable 3:2. 4:3 or 5:4 PR Interval: Variable QRS Width: Normal Grouping: Variable  2nd degree (Type 2) AV Block (Mobitz) Rate: Depends on Rhythm Regularity: Regularly Irregular P Wave: Normal P:QRS Ratio: Variable 3:2, 4:3 or 5:4 PR Interval: Normal QRS Width: Normal Grouping: One beat dropped between groups  3rd Degree AV Block (Complete) Rate: Separate Atrial and Ventricular Rates Regularity: Regular but P and QRS are different P Wave: Present P:QRS Ratio: Variable PR Interval: Variable, no pattern QRS Width: Normal or wide  Wolff-Parkinson White Rate: Depends on the Rhythm Regularity Regular P Wave: Present or buried in the delta wave P:QRS Ratio 1:1 PR Interval: Shortened 0.12 Broad, monomorphic R waves in 1 and V6, with no Q waves. Broad, monomorphic S waves in V1 may have small R wave  Right Bundle Branch Block QRS > 0.12 sec Slurred S wave in lead 1 and V6 Rabbit Ears in V1  Ventricular Tachycardia (Tombstone) Rate: 100 – 120 bpm Regularity: Regular P Wave: Dissociated Atrial Rate P:QRS Ratio: Ventriculoarterial Disassociation PR Interval: None QRS Width: Wide >0.12 Secs, atypical  Ventricular Tachycardia (Picket Fence) Rate: 100 – 120 bpm Regularity: Regular P Wave: Dissociated Atrial Rate P:QRS Ratio: Ventriculoarterial Disassociation PR Interval: None QRS Width: Wide >0.12 Secs, atypical  Torsade De Pointes Rate: 200 – 250 bpm Regularity: Irregular P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: Wide, >.12 sec Grouping Sinusoidal Pattern  Ventricular Fibrillation (Coarse) Rate: Indeterminate Regularity: Chaotic Rhythm P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: Wide and indistinguishable  Ventricular Fibrillation (Medium) Rate: Indeterminate Regularity: Chaotic Rhythm P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: Wide and indistinguishable  Ventricular Fibrillation (Fine) Rate: Indeterminate Regularity: Chaotic Rhythm P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: Wide and indistinguishable  Idioventricular Rate: 20-40 bpm Regularity: Regular P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: Wide >0.12 sec, atypical  Asystole Rate: None Regularity: None P Wave: None P:QRS Ratio: None PR Interval: None QRS Width: None  Long Q T Syndrome Long Q T Syndrome is normally associated as a genetic disorder. However certain types of medication can cause this condition. Such as; antibiotics, antihistamines, antidepressants, Antipsychotics, diuretics and some heart medication. Common symptoms are sudden blackouts, seizures or palpitations. Prolonged episodes of Long Q T can lead to Torsades de-Pointes.  Brugada Syndrome Brugada Syndrome is due to a mutation in the cardiac sodium channel gene. This is often referred to as a sodium channelopathy. Over 60 different mutations have been described so far and at least 50% are spontaneous mutations, but familial clustering and autosomal dominant inheritance has been demonstrated.  Types of PVC’s Unifocal — arising from a single ectopic focus; each PVC is identical Multifocal — arising from two or more ectopic foci; multiple QRS morphologies Bigeminy — every other beat is a PVC Trigeminy — every third beat is a PVC Quadrigeminy — every fourth beat is a PVC Couplet — two consecutive PVCs  Unifocal Premature Ventricular Contraction Rate: Depends on the Rhythm Regularity: Irregular P Wave: Not present before PVC P:QRS Ratio: No P waves PR Interval: None QRS Width: Wade >0.12 sec, atypical  Multifocal Premature Ventricular Contraction Rate: Depends on the Rhythm Regularity: Irregular P Wave: Not present before PVC P:QRS Ratio: No P waves PR Interval: None QRS Width: Wade >0.12 sec, atypical  ST Depression Sinus Rhythm Rate: Depends on the Rhythm Regularity: Regular P Wave: Normal P:QRS Ratio: 1:1 PR Interval: Prolonged >0.20 QRS Width: Normal Areas of Infarction  ST Elevation Sinus Rhythm Rate: Depends on the Rhythm Regularity: Regular P Wave: Normal P:QRS Ratio: 1:1 PR Interval: Prolonged >0.20 sec QRS Width: Normal Evolution of an MI  Reperfusion Arrythmias Reperfusion arrythmias can be caused by: changes to the smallest blood vessels death of myocytes (heart muscle cells) rupture of a layer of your heart wall A RA is an abnormal heart rhythm that affects how efficiently your heart functions. The rhythm disturbance that results from reperfusion is often located in your heart’s lower chambers (ventricles), which pump blood to your lungs and the rest of your body. Accelerated idioventricular rhythm: This type of arrhythmia is an abnormal rhythm involving the ventricles. It often occurs when blood flow is restored after a heart attack. Atrial fibrillation (AF or AFib): During AFib, there’s an irregular and accelerated beating of the atria. It’s the most common RA, representing up to 28% of arrhythmias following reperfusion. Atrioventricular block, sometimes called “heart block”: This arrhythmia occurs when the electrical signals controlling your heartbeat become entirely or partially blocked. Sinus bradycardia: Sinus bradycardia is a slow heart rhythm originating in the sinus node, the collection of cells known as the heart’s “natural pacemaker.” Ventricular tachycardia: Ventricular tachycardia is an abnormally rapid heart rate originating in the ventricles.  Paediatric ECG Differences In contrast to adult ECGs, paediatric ECGs exhibit key differences. Fortunately, the majority of these differences are predictable based on normal development and physiology. The neonatal heart is smaller (smaller volume chambers and lower muscular mass) and is more dependent on the right ventricle than the adult heart. Due to the smaller muscular size, electrical impulses travel more quickly, leading to shortened durations and intervals. Additionally, the heart rate is increased. Electrical durations and intervals seen on ECG will increase and the heart rate will decrease as the patient ages and the heart enlarges. The left ventricle (LV) in the adult is larger than the right ventricle (RV) and the LV thus accounts for most of the electrical forces. In the paediatric patient, the RV is relatively larger (see table), and is most dominant at 36 weeks of gestational age. The LV to RV ratio reaches adult proportions by 1-2 months of age. These dynamic changes lead to the changes in the morphology of ECG tracings as the patient ages.  Paediatric ECG Differences Heart Rate: The neonatal heart rate is faster, as the small, noncompliant heart is dependent on heart rate rather than stroke volume to maintain cardiac output. The normal sinus rate decreases from 140 bpm at 1 month of age, to 120 bpm by 2 years of age, to 90 bpm by 10 years of age, and to 60-70 bpm for adolescents, approaching adult range. QT Interval: The QT interval is a reflection of the function of ion channels involved in repolarization and not myocardial thickness; it is most strongly modified by the HR. The baseline elevated paediatric heart rate increases the corrected QT interval (QTc). QTc = QTmeasured/HR Voltages: Neonatal voltages are overall smaller, and scale (the number of millimetres used to represent 1 mV) is often changed to optimize the ECG display. Impulses: The timing of electrical impulses is faster in the smaller heart. The PR interval is shorter in the neonate (~100 ms) and slowly increases to the adult level of ~160 ms by late adolescence. Similarly, the QRS duration is shorter in the neonate at ~50 ms and lengthens to the adult range of ~90 ms as the heart enlarges. QUESTIONS ?