Arrhythmias - Arrythmias: Sinus, Supraventricular, and...

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Unformatted text preview: Arrythmias: Sinus, Supraventricular, and Sinus, Ventricular Arrythmias Arrythmias of sinus origin Arrythmias Ectopic rhythms Ectopic – Atrial, junctional, and ventricular Conduction blocks – Conduction – Atrioventricular (Chapter 4) – Right or left bundle branch (Chapter 4) Pre-excitation Syndromes – due to bypass tracts in Pre the atria or AV area (Chapter 5) 1 Electrical Conduction System SA node SA AV node AV Bundle of His Bundle Purkinjie Fibers Purkinjie Basic ECG Rhythm Terminology normal sinus rhythm (NSR) normal sinus arrhythmia sinus ectopic beat, ectopy, ectopic pacemaker ectopic supraventricular rhythm supraventricular – atrial – A-V nodal (junctional) Ventricular rhythm Ventricular Escape beat or escape rhythm Escape 2 Identification of the Origin of an Ectopic Beat 1. Is there a P wave? 2. Does a P wave precede each QRS complex? 3. QRS complex width: < 0.10 sec 4. Is the rhythm regular or irregular? Sinus Rhythms Sinus bradycardia – heart rate < 60 bts•min-1 Sinus Sinus tachycardia – heart rate > 100 bts•min-1 Sinus Sinus arrhythmia – Is most notably due to Sinus effects of breathing. – Increased heart rate with inhalation – Decreased heart rate with exhalation ? Sinus arrest or exit block Sinus 3 Mechanisms of Abnormal Electrical Impulse Formation Enhanced automaticity – abnormal condition Enhanced of latent pacemaker cells in which their firing rate is increased beyond their inherent rate Thaler, pg 113 4 Mechanisms of Abnormal Electrical Impulse Formation (con’t) Reentry – progression of an electrical impulse is delayed or blocked in one or more segments of the electrical conduction system while being conducted normally through the rest of the conduction system Atrial premature beat P wave is altered in shape compared to other wave P waves and comes early. QRS complex – normal shape and duration QRS Cycle comes early, (i.e. distance between 2 Cycle QRS complexes is less than adjacent cardiac cycles) 5 Junctional Premature Beat single ectopic beat that originates in the AV node or single Bundle of His area of the condunction system – Retrograde P waves immediately preceding the QRS – Retrograde P waves immediately following the QRS – Absent P waves (buried in the QRS) Goldberger & Goldberger, p 164 6 AV node as a pacemaker Goldberger & Goldberger, p 163 Causes of PAC and PJC Cause Cause – Digitalis toxicity – Myocardial Infarction – Myocardial Ischemia – ingestion of caffeine or amphetamines Clinical Significance Clinical 7 Atrial Flutter Regular rhythm with P waves appearing at a rate Regular of 250 to 300 bts•min-1 P waves are noted for there “saw tooth” pattern, waves and or flutter waves Can be in normal hearts or in those with disease Can Most likely due to AV block, creating a reentry Most circuit 8 Atrial Flutter (example) Saw Tooth Regular Ventricular Rhythm Atrial Fibrillation In this rhythm the AV node is bombarded with impulses In at a rate of 300 + times per min. P waves are not distinguishable on the ECG, and appear waves as “fibrillation waves or f waves.” QRS complexes are irregular in rhythm with normal QRS duration Causes – mitral valve or coronary artery disease, long Causes standing hypertension is still the most common cause 9 Atrial Fibrillation (example) Fine fib waves Course fib waves Irregular Ventricular Rhythm 10 Junctional Escape Beat JEB PJC JEB PJC Goldberger & Goldberger, p 163 11 Junctional Rhythm Rhythm •Rate: •Rhythm: •P wave: 40 to 60 beats/minute (atrial and ventricular) regular atrial and ventricular rhythm usually inverted, may be upright; may precede, follow or be hidden in the QRS complex; may be absent •PR interval: not measurable or less than .20 sec. •QRS and T wave : usually normal Junctional Escape Rhythm Goldberger & Goldberger, 1994 12 Junctional Rhythms Causes Causes – – – – – – – – – – Digitalis toxicity Inferior wall MI Myocardial Ischemia Increased vagal tone Rheumatic heart disease Valvular disease Organic disease of the SA node Verapamil toxicity Anticholinesterase toxicity May occur immediately after surgery Paraoxysmal Supraventricular Tachycardia (PSVT) Tachycardia (PSVT) Rate: Rate 160 to 240 beats/minute Rhythm: Rhythm regular atrial and ventricular P wave: wave usually inverted, may be upright; may precede, follow or be hidden in the QRS complex; may be absent PR interval: not measurable or less than .12 sec. PR QRS and T QRS wave : usually normal usually 13 PSVT (example) Sudden run of 3 or more premature supraventricular (junctional) beats Etiology of PSVT 2 most common types of PSVT SA SA AV BT AV 14 Carotid Massage Can help to diagnose and terminate PSVT Thaler, 99 Thaler, 99 Ventricular Arrythmias Supraventricular area fails to fire, which results Supraventricular in ventricular ectopic beat Premature ventricular contraction (PVC) – by Premature far the most common. – No visible P wave – QRS > 0.12 seconds in length and is bizarre in morphology – May be common 15 Types of PVCs Uniform Uniform Multiform Multiform PVC rhythm patterns PVC – Bigeminy – PVC occurs every other complex – Couplets – 2 PVCs in a row – Trigeminy – Two PVCs for every three complexes Malignant PVC patterns Frequent PVCs Frequent Multiform PVCs Multiform Runs of consecutive PVCs Runs R on T phenomenon – PVC that falls on a T on wave PVC during acute MI PVC 16 Thaler, 99 Thaler, 99 17 Ventricular Rhythms Ventricular tachycardia (VTach) Ventricular – 3 or more PVCs in a row at a rate of 120 to 200 bts•min-1 – Most likely due to acute infarction and/ or ischemia Ventricular fibrillation (VFib) Ventricular – Preterminal event in which myocardium is “dying” – No visible P or QRS complexes. Waves appear as fibrillating waves VTach Vfib 18 Torsades de Pointes Type of VT known as “twisting of the points.” Type Usually seen in those with prolonged QT Usually intervals caused by – Pharmacologic agents Accelerated Idioventricular Rhythm Benign rhythm sometimes seen in acute infarction at a rate of 50 to 100 beats per minute 19 Non-pharmacoligic Treatment Programmed Electrical Stimulation Programmed – More of a diagnostic procedure to determine origin of the arrhythmia in order to administer proper treatment – Recurrent VT or experienced sudden death – Can even use catheter ablation to treat the malignant pathway Implantable defibrillators Implantable Goldberger & Goldberger, 1994 20 Goldberger & Goldberger, 1994 A 50 year old man with chest pain for 24 hours 21 ...
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This note was uploaded on 01/16/2012 for the course KINE 430 taught by Professor Dr.jenniferblevins-mcnaughton during the Fall '11 term at Tarleton.

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