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Arrhythmias. Dr. Ahmad Hersi Med 441 6/1/2009. Conduction System. Septal Branch. Depolarization Sequence. Catechism. Identification Quality Rate Rhythm Axis Waves and intervals Specifics. I. II. aVF. Frontal (limb lead) axis. I. II. aVF. Limb-lead Misplacement.
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Arrhythmias Dr. Ahmad Hersi Med 441 6/1/2009
Conduction System Septal Branch
Catechism Identification Quality Rate Rhythm Axis Waves and intervals Specifics
I II aVF Frontal (limb lead) axis
I II aVF Limb-lead Misplacement
Precordial Leads V4: 5th ICS mid-clavicular line V6: lateral to V4 mid-axillary line V1: Right 4th ICS parasternal V2: Left 4th ICS parasternal
Start if possible on a beat whose QRS (usually R wave) is on the border of a large square Count Large squares (0.2 seconds each) 300 100 60 40 150 75 50 Rate This tracing example shows a rate of 100 bpm
Rate determination for irregular rhythm * 8 times 10 = 80 bpm 30 For irregular rhythm (such as atrial fibrillation), the method shown on the last slide may be inaccurate. Use this alternate method. Start as before by finding a QRS that lands on the border of a large square (*). Then count 30 large squares (= 0.2 X 30 = 6 seconds). Add up all beats (QRSs) that land within the interval (not counting that first beat (*) and multiple by 10. This equals the number of beats per minute.
Rhythm “Cherchez la P” • To be convinced of sinus rhythm, you should see a P wave in front of every QRS, and the PR interval should not alter, and be of a plausible length. • Lead II is usually the best lead for seeing P waves, and is often used for rhythm strips.
QRS Axis Left I (-) aVF (-) II (-) I (+) aVF (-) II (-) Right Normal I (+) aVF (+) II (+) I (-) aVF (+) II (+)
I aVF II Quick Method for QRS Axis
The P Wave • Normally from sinus node • Upright in I, II, aVF, V4-V6 • Monophasic (except V1) • Normal ranges: • < 0.12 sec wide • < 2.5 mm tall
The PR Interval • Measure from beginning of P wave to onset of QRS. Usually measure in Lead II • Measure the longest PR interval in the limb leads • Normal range 0.12-0.20 seconds • < 0.12 = Accelerated conduction • > 0.2 = Heart block
The T Wave • T waves may be normally inverted in aVR (almost always), III (frequently), and V1 (sometimes). • T waves are “tall” if their height is: • > 50% QRS height • > 5mm in limb lead • > 10 mm in precordial lead
The U Wave • Causes: • Normal • Bradycardia • CAD • Hypertension • Hypokalemia • Hypercalcemia
Left Ventricular Hypertrophy * * * *
Case 1 • 65 yr woman, presents to ER with Dizziness for 2hrs. • In the past, a doctor told her that her heart rate is slow. • Healthy otherwise, and is not on med’s. • O/E : Bp=170/100
Management • ABC • V/S • If serious symptoms or signs: - Atropine 1 mg - TCP - Dopamine - Epinephrine - Isoproterenol
Management • If clinically stable: - Prepare for TVP as a bridge device
Case 2 • 25yr old woman • 1 hr h/o palpitation • No other cardiac symptoms • Intermittent palpitation in the last 3 months , this episode is long • BP= 120/70
Management Narrow Complex tachycardia Serious signs and symptoms Stable clinically Vagal maneuvers Immediate Cardioversion Adenosine or Verapamil Consider BB, Diltiazem , or Digoxin
Case 3 • 60 yrs C/O sudden onset dyspnea for last 1/2hr • Past MI 1 yr ago, received thrombolytics. • His ECHO at the time revealed impaired LV systolic function • Med’s: ASA, Bisoprolol, Lisinopril, and Lasix • On exam , BP=80/50