ECG Dysrhythmia Interpretation PDF

Chapter 7: Dysrhythmia Interpretation and Management  Objectives At the end of this lecture you will be able to: Identify major dysrhythmias including Sinus Tachycardia, Sinus Bradycardia, Sinus Arrhythmia, Sinus Pauses, Atrial Tachycardia, Atrial Flutter, Atrial Fibr...

Chapter 7: Dysrhythmia Interpretation and Management  Objectives At the end of this lecture you will be able to: Identify major dysrhythmias including Sinus Tachycardia, Sinus Bradycardia, Sinus Arrhythmia, Sinus Pauses, Atrial Tachycardia, Atrial Flutter, Atrial Fibrillation, Junctional Escape Rhythm, Ventricular Tachycardia, Ventricular Fibrillation, PVCs and Asystole. Identify the characteristic of each dysrhythmia Identify and discuss the possible causes, patient responses and treatments of each dysrhythmia Demonstrate the use of the systematic ECG rhythm analysis Describe appropriate interventions for common dysrhythmias  What is dysrhythmia?? It is an abnormal cardiac rhythm, also called (arrhythmia) Basic dysrhythmia classification: – Dysrhythmia of the SA node – Dysrhythmia of the atria – Dysrhythmia of the AV node – Dysrhythmia of the ventricles Systematic ECG rhythm analysis Step 1: Calculate rhythm rate. Step 2: Determine rhythm regularity. Step 3: Assess the P waves. Step 4: Determine PR interval. Step 5: Determine QRS duration. Step 6: Assess ST segment Step 7: Assess P:QRS ratio.  Normal Sinus Rhythm Rate 60 – 100 bpm Regularity regular P waves normal PR interval normal QRS duration normal ST segment Isoelectric P:QRS ratio 1:1  Classification of Dysrhythmias The basic dysrhythmias are classified based on their site of origin, including: SA node. Atrial. AV node or junctional. Ventricular  Dysrhythmia of the SA node Sinus Tachycardia Sinus Bradycardia Sinus dysrhythmia Sinus pauses / arrest  Dysrhythmia of the SA node 1-Sinus Tachycardia Rate >100 bpm Regularity regular P waves normal PR interval normal / less QRS duration normal ST segment Isoelectric P:QRS ratio 1:1  Sinus Tachycardia Causes: – Stimulation of the sympathetic nervous system. – Response to fear or pain and anxiety – Hyperthyroidism, heart failure, anemia, – Exercise – Stimulants ( caffeine, decongestants, stress and pain) – High temp (fever). – Alterations in fluid status (hypovolemia) Patient response: – Decreased ventricles filling time →Low cardiac output – Decrease coronary filling during diastole  Treatment Treat the underlying cause, e.g. pain medications are administered to treat pain or antipyretics are given to treat fever. No medication to be give to slow down the heart rate.  Dysrhythmia of the SA node 2-Sinus Bradycardia ▪ Rate < 60 bpm ▪ Regularity regular ▪ P waves normal ▪ PR interval normal ▪ QRS duration normal ▪ ST segment isoelectric ▪ P:QRS ratio 1:1  Sinus Bradycardia Causes: – Athletes – Increased vagal stimulation (parasympathetic nervous system) – Drug effects e.g. digoxin , or AV nodal blocking agents, including calcium channel blockers and beta blockers;or (sometimes desired result) – Myocardial Infarction (MI) – SA node diseases – Hypoxemia and hypothermia – Increased intracranial pressure  Sinus Bradycardia Patient response: – Decreased in cardiac output → hypotension → decrease organ perfusion Treatment : – Treat the underlying cause – Assess for hemodynamic instability related to the bradycardia. If the patient is symptomatic, – Administer atropine and/ or TCP (transcutaneous pacing) when symptomatic bradycardia  Quick Quiz! A symptom of decreased cardiac output that is an indication of decreased coronary artery perfusion is: A. Cyanosis B. Chest pain C. Dyspnea D. Decreased urine output 15  Dysrhythmia of the SA node 3- Sinus Arrhythmia Rate may be normal Regularity irregular P waves normal PR interval normal/ abnormal QRS duration normal ST segment isoelectric P:QRS ratio 1:1 Sinus arrhythmia is a cyclical change in heart rate that is associated with respiration.  Sinus Arrhythmia Patient response: – This rhythm is tolerated well. Treatment : – No treatment is required. Dysrhythmia of the SA node 4- Sinus Pauses  Dysrhythmia of the SA node 4- Sinus Pauses Rate may be normal Regularity irregular for the period of the pause ------------------ but regular when sinus rhythm resumes. P waves normal PR interval normal QRS duration normal ST segment isoelectric P:QRS ratio 1:1  Sinus Pauses ▪ Causes: – Hypoxemia; ischemia or damage of the sinus related to myocardial infarction. – AV nodal blocking medications such as beta blockers, calcium channel blockers, and digoxin. – Increased vagal tone may cause sinus exit block. ▪ Patient response: – Single pauses may not be significant. – Frequent pauses may result in a severe bradycardia and signs and symptoms of decreased cardiac output.  Sinus Pauses Treatment :  If the patient is symptomatic with significant numbers of pauses may require temporary and permanent implantation of a pacemaker.  Causes are explored and treated.  Medications may need to be adjusted or discontinued.  Dysrhythmia of the atria Atrial Tachycardia Atrial Flutter Atrial Fibrillation  Dysrhythmia of the atria 1- Atrial Tachycardia Atrial tachycardia is a rapid rhythm that arises from an ectopic focus in the atria. Rate 150-250 bpm Regularity regular P waves merged with T wave if present PR interval not measurable QRS duration normal / less  Atrial Tachycardia Causes: – Patient with cardiac diseases – Could occur in healthy patients – Electrolyte imbalance – Digitalis toxicity – Ischemic heart disease – Valvular abnormalities – Lung disease  Atrial Tachycardia Patient response: – Low cardiac output – Life-threatening Treatment: – Assessing patient tolerance to tachycardia – Cardioversion – Medications include adenosine , beta-blockers, calcium channel blockers, and amiodarone.  Dysrhythmia of the atria 2- Atrial Flutter Rate atrial rate (250 to 350 bpm) ventricular rate (varies) Regularity regular P waves classic saw-tooth in leads II, III, and aVF PR interval unmeasurable QRS duration normal to wide P:QRS ratio No. of P waves :1  Atrial Flutter Figure 7-33. Atrial flutter. A, Flutter waves show sawtooth pattern. B, Enlarged view shows one large box between flutter waves. Copyright © 2013, 2009, 2005, 2001, 1997, 1993 by Saunders, an imprint of Elsevier 27 Inc.  Atrial flutter Arises from single irritable focus in the atria. Causes: – Hyperthyroidism – Hypoxemia – Ischemic heart disease – Heart failure – Lung disease – Alcoholism  Atrial flutter Patient response: – Asymptomatic – Fast ventricular rate could result in low cardiac out put Treatment: – Anticoagulation therapy – Cardioversion done after receiving anticoagulation for 6 weeks – Electrophysiological treatment (ablation of irritable focus)  Dysrhythmia of the atria 3- Atrial Fibrillation Rate atrial (indiscernible from 350 to 500 bpm) ventricular (varies) Regularity irregular P waves absent (fine waves) PR interval unmeasurable QRS duration normal/ wide  Atrial Fibrillation Atrial fibrillation arises from multiple ectopic foci in the atria, causing chaotic quivering of the atria and ineffectual atrial contraction. Most common rhythm with clinical importance Erratic impulses formation throughout the atria. Causes: – Hyperthyroidism - Ischemic heart disease – Valvular disease - Heart failure – Lung disease  Atrial Fibrillation Patient response: – Patient may or may not be aware of Atrial Fibrillation – Fast ventricular rate could result in low cardiac out put Treatment: – Anticoagulation therapy – Cardioversion done after receiving anticoagulation for 4 to 6 weeks – Emergent cardioversion is done if hemodynamic unstable – Electrophysiological treatment (ablation of irritable focus)  Dysrhythmia of the AV node Junctional Escape (nodal) Rhythm P-wave changes - When the AV node impulse moves forward: No P wave – When the AV node impulse moves backward Shorter PR intervals Inverted P wave - When the impulse is conducted both forward and backward: Retrograde P waves Remember: Normal Cardiac Conduction Pathway  Dysrhythmia of the AV node 1- Junctional Escape (nodal) Rhythm  Dysrhythmia of the AV node Junctional Escape Rhythm Junctional escape rhythm occurs when the dominant pacemaker (SA node) fails to fire. Rate 40 to 60 Regularity regular P wave absent / inverted/ following QRS PR interval normal to short QRS normal ST segment isoelectric  Junctional Escape Rhythm Causes: – Loss of SA node activity Patient response: – Assessed for tolerating bradycardia Treatment: Administer atropine and/ or TCP, dopamine infusion, or epinephrine when symptomatic bradycardia Dysrhythmia of the ventricles PVCs Ventricular Tachycardia Ventricular Fibrillation Asystole  Dysrhythmia of the ventricles 1- PVCs (Premature Ventricular Contractions) PVCs are early beats that interrupt the underlying rhythm; they can arise from a single ectopic focus or from multiple foci within the ventricles.  Dysrhythmia of the ventricles A. Unifocal PVCs B. Multifocal Premature ventricular contractions (PVCs). A, Sinus rhythm with unifocal PVCs. 1 is the sinus beat; 2 points to the presence of an inverted T wave. B, Sinus rhythm with multifocal PVCs; note the different configuration of the PVCs, indicating generation from more than one focus  PVCs Bigeminy Trigeminy Quadrigeminy  PVCs Couplet Pairs Triplet  PVCs Causes: – Hypokalemia – Hypomagnesemia – Hypoxemia – Acid-Base imbalance – Ischemic heart disease Patient response: – may be experienced as palpitations. – Patients may become symptomatic if the PVCs occur frequently. Treatment: – Treat underlying cause.  Critical Thinking Challenge Why are multifocal PVCs considered more dangerous than unifocal PVCs? 44  When Are PVCs Dangerous? Frequent Multifocal Two or more in a row R on T – PVC falls into the vulnerable period of the T wave – Ventricular tachycardia or fibrillation can result 45 PVC causing ventricular fibrillation.  Dysrhythmia of the ventricles 2- Ventricular Tachycardia Ventricular tachycardia (VT) is a rapid, life-threatening dysrhythmia originating from a single ectopic focus in the ventricles. Rate greater than 100 bpm Regularity regular P waves absent PR interval unmeasurable QRS duration wide and bizarre  Ventricular Tachycardia (VT) Causes: – Hypokalemia – Hypomagnesemia – Hypoxemia – Acid-Base imbalance – Ischemic heart disease – Valvular disease – Cardiomyopathy  Ventricular Tachycardia (VT) Patient response –VT with pulse: Pulse and blood pressure present → enough cardiac output –Pulseless VT: Cardiac output impaired → lead to cardiac arrest Treatment: – No pulse and blood pressure → Cardioversion – With Pulse and blood pressure → amiodarone or lidocaine.  Dysrhythmia of the ventricles 3- Ventricular Fibrillation(VF) Rate unmeasurable Regularity irregular P waves non PR interval non QRS duration non P:QRS ratio non Ventricular fibrillation (VF) is a chaotic rhythm characterized by a quivering of the ventricles, which results in total loss of cardiac output and pulse. Dysrhythmia of the ventricles Ventricular Fibrillation (VF)  Ventricular Fibrillation (VF) It could be caused by untreated VT Total loss of cardiac output No pulse No BP Immediate BLS and ACLS interventions  Dysrhythmia of the ventricles 4- Asystole  Rate: Heart rate is absent.  Regularity: Heart rhythm is absent.  Interval measurements: PQRST waveforms are absent.  Shape and sequence: Waveform is a flat or undulating line on the monitor.  Figure 7-48. A, Asystole. B, Ventricular standstill Copyright © 2013, 2009, 2005, 2001, 1997, 1993 by Saunders, an imprint of Elsevier 55 Inc.  Asystole: Causes: Asystole is usually preceded by another dysrhythmia such as VF or ventricular escape rhythm. Patient response: The patient is in cardiac arrest. Care and treatment: BLS and ACLS protocols are initiated.