2 Course ObjectivesTo recognize the normal rhythm of the heart - “Normal Sinus Rhythm.”Understand normal conduction of the heart
3 1887 British physiologist Augustus D 1887 British physiologist Augustus D. Waller of St Mary's Medical School, London publishes the first human electrocardiogram. It is recorded with a capilliary electrometer from Thomas Goswell, a technician in the laboratory. Waller AD. A demonstration on man of electromotive changes accompanying the heart's beat. J Physiol (London) 1887;8: Dutch physiologist Willem Einthoven sees Waller demonstrate his technique at the First International Congress of Physiologists in Bale. Waller often demonstrated by using his dog "Jimmy" who would patiently stand with paws in glass jars of saline. 1889
4 Augustus waller first to His electrocardiograph machine consisted of a Lippmann capillary electrometer fixed to a projector. The trace from the heartbeat was projected onto a photographic plate which was itself fixed to a toy train. This allowed a heartbeat to be recorded in real time. In 1911 he still saw little clinical application for his work.An initial breakthrough came when Willem Einthoven, working in Leiden, Netherlands, used the string galvanometer that he invented in 1903. This device was much more sensitive than both the capillary electrometer that Waller used and the string galvanometer that had been invented separately in 1897 by the French engineer Clément Ader.. Rather than using today's self-adhesive electrodes Einthoven's subjects would immerse each of their limbs into containers of salt solutions from which the ECG was recorded.Einthoven assigned the letters P, Q, R, S and T to the various deflections, and described the electrocardiographic features of a number of cardiovascular disorders. In 1924, he was awarded the Nobel Prize in Medicine for his discovery.- limb leadsMany advancements such as Goldbergers chest leadsR.E.Mason.,I.Likar ( 1966)
5 Impulse Conduction & the ECG Sinoatrial nodeAV nodeBundle of HisBundle BranchesPurkinje fibers
6 The “PQRST” P wave - Atrial depolarization QRS - Ventricular depolarizationT wave - Ventricular repolarization
7 Atrial depolarization The PR IntervalAtrial depolarization+delay in AV junction(AV node/Bundle of His)(delay allows time for the atria to contract before the ventricles contract)
11 Pacemakers of the Heart SA Node - Dominant pacemaker with an intrinsic rate of beats/minute.AV Node - Back-up pacemaker with an intrinsic rate of beats/minute.Ventricular cells - Back-up pacemaker with an intrinsic rate of bpm.
12 The ECG Paper Horizontally Vertically One small box - 0.04 s One large box sVerticallyOne large box mV
13 The ECG Paper (cont)3 sec3 secEvery 3 seconds (15 large boxes) is marked by a vertical line.This helps when calculating the heart rate.
15 Normal Sinus Rhythm“Normal sinus rhythm occurs when the impulse originates in the sino Atrial node and travels through the conduction system in a normal sequence ,at a normal and regular rate” American Heart Association,(2000).homepage:Availablehttp:/
18 Criteria - P waveAn upright rounded P-wave in leads II, III and AVF, and an inverted P-Wave in AVR which precede each QRS Complex.The P wave does not exceed 2.5mm in height.It does not exceed 3mm in width.A biphid P wave is seen in lead V1.
19 Criteria - PR interval PR Interval 0.12 - 0.20seconds. Delay at AV nodeProtect ventriclesAllow for ventricular filling
20 Criteria QRS complex Should not exceed 0.12 seconds in duration. Should not exceed 27mm in height.Sharp narrow complexRS in V1, QRS in V6
21 Criteria T waveThe deflection produced by repolarisation of the ventricles.No clearly defined rangeGeneral rule - T wave should not be more than 1/2 the height of the preceding QRS
22 Criteria - QT interval QTc Interval Should not exceed 0.42 seconds (QTc).QT interval corrected to the heart rate.
46 NSR Parameters Rate 60 - 100 bpm Regularity regular P waves normal PR interval sQRS duration sQT interval not exceed seconds.U wave
47 Sinus Bradycardia - Rate < 60 b pm Etiology: SA node is depolarizing slower than normal, impulse is conducted normally (i.e. normal PR and QRS interval).
48 Sinus Tachycardia - Rate > 100 bpm Etiology: SA node is depolarizing faster than normal, impulse is conducted normally.Remember: sinus tachycardia is a response to physical or psychological stress, not a primary arrhythmia.
49 Sinus arrythmia Rate – variable Etiology: SA node is depolarizing t a variable rate , impulse is conducted normally (i.e. normal PR and QRS interval).
50 Normal Rhythms !!! *Sinus Arrest* Considered a ‘Sinus rhythm’ but is abnormal
51 Rhythm 1 Rate? 130 bpm Regularity? regular P waves? normal PR interval?0.16 sQRS duration?0.08 sInterpretation?Sinus Tachycardia
52 Rhythm 2 Rate? 30 bpm Regularity? regular P waves? normal PR interval? QRS duration?0.10 sInterpretation?Sinus Bradycardia
53 ECG INTERPRETATIONIf the normal ECG is known then interpretation of abnormals becomes easier