Presentation on theme: "ELECTROCARDIOGRAM (ECG)"— Presentation transcript:
1 ELECTROCARDIOGRAM (ECG) بسم الله الرحمن الرحيمCardiovascular SystemANALYSISDr.Mohammed Sharique Ahmed QuadriAsst. Professor PhysiologyAlmaarefa CollegeELECTROCARDIOGRAM (ECG)
2 The 12-Leads The 12-leads include: 3 Limb leads (I, II, III) 3 Augmented leads (aVR, aVL, aVF)6 Precordial leads (V1- V6)
3 Views of the Heart Left Lateral portion of the heart( I , Avl, v5,v6) Some leads get a good view of the:Anterior portion of the heart(V1,V2,- setumV3,V4-)- anteriorInferior portion of the heartII, III, aVF
10 1-Determine regularity Look at the R-R distances (using a caliper or markings with a pen on paper).Regular (are they equidistant apart)? Occasionally irregular? Regularly irregular? Irregularly irregular?Interpretation?RRRegular
11 2-Calculating heart rate H.R = NO OF SMALL SQURES BETWEEN R-R WAVESORH.R = NO OF BIG SQURES BETWEEN R-R WAVES
12 Calculate Rate Option 2 R wave Find a R wave that lands on a bold line.Count the # of large boxes to the next R wave. If the second R wave is 1 large box away the rate is 300, 2 boxes - 150, 3 boxes - 100, 4 boxes - 75, etc. (cont)R wave
13 3-Assess the P waves Are there P waves? Do the P waves all look alike? Do the P waves occur at a regular rate?Is there one P wave before each QRS?Interpretation?Normal P waves with 1 P wave for every QRS
20 SINUS ARHYTHMIA INTERPRETE THE ECG ? Observe Variation in Heart Rate during Inspiration and Expiration.[Increased Heart Rate during Inspiration]
21 Atrial Fibrillation Deviation from NSR No organized atrial depolarization, so no normal P waves (impulses are not originating from the sinus node).The atrial rate is usually above 350 beats per minuteAtrial activity is chaotic (resulting in an irregularly irregular rate).Common, affects 2-4%, up to 5-10% if > 80 years old
23 AV Nodal Blocks1st Degree AV Block2nd Degree AV Block, MobitzType I2nd Degree AV Block,MobitzType II3rd Degree AV Block
24 Rate? 60 bpm Regularity? regular P waves? normal PR interval? 0.36 s Take a look at this ECG. What do you noticeRate?60 bpmRegularity?regularP waves?normalPR interval?0.36 sQRS duration?0.08 sInterpretation?1st Degree AV BlockPR Interval > 0.20 sEtiology: Prolonged conduction delay in the AV node or Bundle of His.
25 2nd Degree AV Block, Type I Take a look at this ECG. What do you noticeRate?50 bpmRegularity?regularly irregularP waves?normal, but 4th no QRSPR interval?lengthensQRS duration?0.08 sInterpretation?2nd Degree AV Block, Type IPR interval progressively lengthens, then the impulse is completely blocked (P wave not followed by QRS).Etiology: Each successive atrial impulse encounters a longer and longer delay in the AV node until one impulse (usually the 3rd or 4th) fails to make it through the AV node.
26 2nd Degree AV Block, Type II Take a look at this ECG. What do you noticeRate?40 bpmRegularity?regularP waves?normal, 2 & 3 no QRSPR interval?0.14 sQRS duration?0.08 sInterpretation?2nd Degree AV Block, Type IIOccasional P waves are completely blocked (P wave not followed by QRS).Etiology: Conduction is all or nothing (no prolongation of PR interval); typically block occurs in the Bundle of His.
27 Interpretation? 3rd Degree AV Block Rate? 40 bpm Regularity? regular Take a look at this ECG. What do you noticeRate?40 bpmRegularity?regularP waves?no relation to QRSPR interval?noneQRS duration?wide (> 0.12 s)Interpretation?3rd Degree AV BlockEtiology: There is complete block of conduction in the AV junction, so the atria and ventricles form impulses independently of each other. Without impulses from the atria, the ventricles own intrinsic pacemaker kicks in at around beats/minute.
28 RememberWhen an impulse originates in a ventricle, conduction through the ventricles will be inefficient and the QRS will be wide and bizarre.
29 Determination of Mean Electrical Axis Axis refers to the mean QRS axis (or vector) during ventricular depolarization. As you recall when the ventricles depolarize (in a normal heart) the direction of current flows leftward and downward because most of the ventricular mass is in the left ventricle. We like to know the QRS axis because an abnormal axis can suggest disease such as pulmonary hypertension from a pulmonary embolism.
30 When a vector is exactly horizontal and directed toward the person’s left side,the vector is said to extend in the direction of 0 degreesFrom this zero reference point, the scale ofvectors rotates clockwise:
33 FORMATION OF HEXAAXIAL SYSTEM -90aVR aVLIIII II+90aVF
34 Determination of Mean Electrical Axis The QRS axis is determined by overlying a circle, in the frontal plane. By convention, the degrees of the circle are as shown.The normal QRS axis lies between -30o and +110o.A QRS axis that falls between -30o and -90o is abnormal and called left axis deviation.0o30o-30o60o-60o-90o-120o90o120o150o180o-150oA QRS axis that falls between +110o and +180o is abnormal and called right axis deviation.A QRS axis that falls between +180o and -90o is abnormal and called Indeterminant (extende rt axis ) .
35 How to calculate the qrs axis Leads & there isoelectric partners
37 How to calculate the QRS axis … if the QRS is negative in lead I and negative in lead II what is the QRS axis? (normal, left, right or right superior axis deviation)QRS ComplexesI aVFAxisnormalleft axis deviationright axis deviationright superior axis deviation/ indeterminant