Module 2 interpreting ecg rythm strips-1-converted
- 1. MODULE2 Interpreting E C G rhythm STRIPS
- 2. Objectives • Utilize asystematic process whenapproaching the interpretation of theECG. • Identify normal and abnormal components on the ECG.
- 4. Cardiac Anatomy ▪ 2upper chambers ▪ Right and left atria ▪ 2lower chambers ▪ Right and left ventricle ▪ 2Atrioventricular valves (Mitral &Tricuspid) ▪ Open with ventriculardiastole ▪ Closewith ventricularsystole ▪ 2Semilunar Valves(Aortic &Pulmonic) ▪ Open with ventricularsystole ▪ Open with ventriculardiastole
- 6. ▪ 2major vessels of thecoronary circulation ▪ Left main coronaryartery ▪ Left anterior descending and circumflexbranches ▪ Right main coronaryartery ▪ Left and right coronary arteries originate at the base of the aorta from openings called the coronary ostia behind the aortic valve leaflets. Anatomy Coronary Arteries
- 7. Normal Conduction System Sinoatrial node Internodalpathway A Vnode Bundle of His BundleBranches Purkinjefibers
- 8. Pacemakers of the Heart • SA Node -Dominant pacemakerwith an intrinsic rate of 60 -100beats/minute. • AVNode -Back-up pacemaker with an intrinsic rate of 40 -60 beats/minute. • Ventricular cells-Back-up pacemaker with an intrinsic rate of 20 -45bpm.
- 9. ECGs?
- 10. Basic E C G Interpretation STANDARD CALLIBRATION Speed = 25mm/s Amplitude = 0.1mV/mm • 1large square: 0.2s(200ms) 1small square: 0.04s(40ms) • 1mV:10mm high • 0.1mV amplitude
- 11. OBTAINA NECG,ACT CONFIDENT,READ THE PT DETAILS
- 12. OBTAINA NECG,ACT CONFIDENT,READ THE PT DETAILS • Some ECGmachines come with interpretation software. • Thisone says the patient is fine. DONOTtotally trust this software.
- 13. ECGLIMB LEADREVERSAL • LeadI or aVLis completely inverted (P wave, QRScomplex andTwave). • Lead aVRoften becomespositive. • The P-wave is unexpectedly larger in lead I than lead II (it is usually the other way around).
- 14. The best way to interpret an EC G is to do it step-by-step Step 1:Rate Step 2:Rhythm +Regularity Step 3:P-wave Step 4: PR-interval Step 5:QRSComplex Step 6: STSegment andTwaves Step 7:QTinterval (Include TandU wave) Step 8 :CardiacAxis Step 9: Other ECGsigns
- 15. THE NORMAL SIZE <3small square <3-5 small square <2large square <2small square
- 16. PQRSTConfiguration One completecardiac cycle =P ,Q, R, S, (QRS complex), and Twave P wave First deflectionRounded and upright in lead II Amplitude: 0.5-2.5mn Duration: 0.10s Atrial depolarization PR Interval Beginning of Pwaveto beginning of QRS complex Duration: 0.12s-0.2s Atrial depolarization +conductiondelay through AVjunction (AVN+ Bundle ofHis) QRS Complex Beginning of Qwaveto the end of Swave Duration: 0.06-0.12s Ventricular depolarization ST Segment Between Swave tothe beginning of Twave Normal STsegmentis flat (isoelectric) Isoelectric, ventricle stilldepolarized QT Interval Beginning of QRS complex to the end of T wave Duration: ½of the distance of RRinterval Ventricular depolarization +repolarization Mechanical contraction of ventricle T Wave End of STsegmentto the end ofTwave Rounded and asymmetrical Upright in lead II Amplitude: <5mm Ventricular repolarization
- 17. 6-STEPSAPPROACHFORECGRECOGNITION STEP1– HEARTRA TE Bpmcalculation=ventricularrate 6smethod:countRwaveswithin6sstripmultiplyby10 300method:300/nolargesquaresbetweenQRS Normal:60-100bpm Bradycardia:<60bpm Tachycardia:>100 STEP2– HEARTRHYTHM IntervalsbetweenRwaves(measurefromRtoR) Regularorirregular? AretherhythmSINUS? Regular: Intervalconsistent Irregular: Irregularpattern Sinus rhythm: P-QRS-T STEP3– PWAVE LookatthePwaves ArePwavespresent? ArePwavesoccurringregularly? IsthereonePwavepresentforeveryQRScomplex present? ArethePwavessmooth,rounded,anduprightin appearance,oraretheyinverted? 5.DoallPwaveslooksimilar? Every1PforeachQRScomplex More than 1Pwave indicates AVblock None: rhythm isjunctional/ventricular STEP4 – PRINTERVAL Onset of Pwave to onset of QRScomplex Normal=0.12–0.20seconds(3-5smallsquares) ArethePRintervalsgreaterthan0.20seconds? ArethePRintervalslessthan0.12seconds? 3.ArethePRintervalsconsistentacrosstheECGstrip? PRIshorter:presenceof accessorypathwaysthat bypassedtheAVN PRIlonger: AVblock STEP5– QRSCOMPLEX Measuredfromthestartof Qwaveto theendof theSwave Normal=0.06-0.12seconds(1½to 3smallboxes) AretheQRScomplexesgreaterthan0.12seconds(in width)? AretheQRScomplexeslessthan0.06seconds(in width)? 3.AretheQRScomplexessimilarinappearanceacross theECGstrip? WidenedQRS: BBB Pre-excitation syndrome Electrolytes imbalance:Hyperkalemia Pacedrhythm Impulse originated from the ventricle STEP6– EXTRASorIDENTFYING FEA TURES Anyectopicbeats? ConsiderACSandMI(STsegmentandTwave) Identifyingfeatures? ProlongedQTIsyndrome
- 18. STEP 1: RATE
- 19. CALCULATING RATE • Asa general interpretation, look at lead II at the bottom part of the ECGstrip Thislead is the rhythm strip which shows the rhythm for the whole time the ECGis recorded. Lookat the number of squarebetween one R-Rinterval • Tocalculate rate, use any of the following formulas: OR Rate = 300 the number of BIG SQUARE between R-Rinterval 1500 the number of SMALL SQUARE between R-R interval Rate =
- 20. CALCULATING RATE For example: Rate = 300 3 Rate = 1500 15 or Rate = 100 beats per minute
- 21. CALCULATING RATE • If you think that the rhythm isnot regular, count the number of electrical beats in a6-secondstrip andmultiply that number by10.(Note that some ECGstrips have 3seconds and 6 seconds marks) Example below: 1 2 3 4 5 6 7 8 = (Number of R waves in 6-second strips) x 10 = 8 x 10 = 80 bpm Rate There are 8 R waves in this 6-seconds strip.
- 22. INTERPRETATION Interpretation Bpm Causes Normal 60-99 Bradycardia <60 Hypothermia, increased vagal tone (due to vagal stimulation or e.g. drugs), athletes (fit people) hypothyroidism, beta blockade, markedintracranial hypertension, obstructive jaundice, and even in uremia, structural SAnode disease, or ischaemia. Tachycardia >100 Any cause ofadrenergic stimulation (including pain); thyrotoxicosis; hypovolaemia; vagolyticdrugs (e.g. atropine) anaemia, pregnancy; vasodilatordrugs, including many hypotensive agents;FEVER, myocarditis
- 23. SinusBradycardia • Rate < 60bpm, otherwise normal
- 24. SinusTachycardia Rate >100bpm • Rate > 100bpm, otherwise normal
- 25. STEP 2: RHYTHM
- 26. RHYTHM • If in doubt, use apaper strip to map out consecutive beats and see whether the rate is the same further along the ECG. • Measure ventricular rhythm bymeasuring the R-Rinterval • Isthe rhythm regular orirregular?
- 27. Regular rhythm • Sinus rhythm • Sinus bradycardia • Sinustachycardia • Atrial tachycardia • Junctional rhythm • SVT(AVNRT,AVRT) • Atrial flutter with fixed block Irregular rhythm • Atrial fibrillation • Atrial flutter with variable block • SRwith ectopicbeats • Multifocal Atrialtachycardia (MAT)
- 28. STEP 3: P- WAVE
- 29. P -WAVE Normal P-wave • 3small square wide, and 2.5small square high • Always positive in lead I and II in NSR • Always negative in lead aVRin NSR • Commonly biphasic in leadV1
- 30. P wave 1. Are Pwaves present? 2. Is there 1Pfor each QRScomplex? 3. Are the Pwaves smooth, rounded and upright in appearance except inverted Pwaves in leadaVR? 4. Do all Pwaves look similar?
- 31. INTERPRETATION • Sinus rhythm: Every 1Pfor each QRScomplex • More than 1Pwave indicates AVblock • None: Rhythm is junctional or ventricular in origin
- 32. RHYTHM Normal SinusRhythm • ECGrhythm characterized by a usual rate of anywhere between 60-99 bpm, every Pwave must be followed byaQRS.Normal duration of PRinterval is3-5small squares.ThePwave isupright in leadsI andII.
- 33. P -WAVE Ppulmonale • Tall peaked Pwave • Generally due to enlarged rightatrium- commonly associated with congenital • heart disease, tricuspid valve disease,pulmonary hypertension and diffuse lungdisease BiphasicPwave • It’s terminal negative deflection more than 40 ms wide and more than 1mm deep is an ECGsign of leftatrial enlargement Pmitrale • Wide Pwave, often bifid, may be due to mitral stenosisor left atrialenlargement
- 34. STEP 4: PR- INTERVAL
- 35. PR INTERVAL NORMALPRINTERVAL PR-Interval 3-5 small square (120-200ms) Long PRinterval may indicate heart block Short PRinterval may disease like Wolf-Parkinson- White
- 36. PR-INTERVAL Wolff–Parkinson–White Syndrome Wolf ParkinsonWhiteSyndrome • One beat from arhythm strip in V2 demonstrating characteristic findingsin WPWsyndrome • Note the characteristic: • Delta wave (above the blue bar), the short PRinterval (red bar) of 0.08 seconds, and the longQRScomplex (green) at 0.12seconds • Accessory pathway (Bundle of Kent) allows early activation of the ventricle (delta wave and short PRI)
- 38. QRScomplex< 3small square (0.10sec) QRS COMPLEX Prolonged indicates hyperkalemia or BBB Qwave amplitude lessthan 1/3QRSamplitude(R+S)or <1small square
- 39. INTERPRETATON • Narrow complexes (QRS<100ms) are supraventricular inorigin. • Broad complexes (QRS>100ms) may beeither: – Ventricular in origin – Due to aberrant conduction e.g. due to bundle branch block – Electrolytes imbalance e.g.Hyperkalaemia – Ventricular pacedrhythm
- 40. QRS COMPLEX Left Bundle BranchBlock(LBBB) indirect activation causes left ventricle contracts later than the right ventricle. QSor rScomplex in V1-W-shaped RsR'wave in V6-M-shaped Right bundle branchblock (RBBB) Indirect activation causesrightventricle contracts later than the left ventricle Terminal Rwave (rSR’) in V1-M-shaped Slurred Swave in V6 -W-shaped Mnemonic: WILLIAM Mnemonic: MARROW
- 41. STEP 6: ST-SEGMENT and T WAVE
- 42. ST SEGMENT NORMALSTSEGMENT STsegment <2-3small square (80 to 120ms) STsegment is isoelectric and at thesame level as subsequent TPsegment
- 43. ST SEGMENT WE DECIDE THIS BY LOOKING AT THE ST SEGMENT IN ALL LEADS Flat (isoelectric) ± Same level with subsequent TP segment Elevation or depression of STsegment by 1mm or more, measured at Jpoint is abnormal. Jpoint is the point between QRSandSTsegment NORMAL STSEGMENT OK,WEGONNATALKABOUTMYOCARDIAL INFARCTION (MI) THEREARE2TYPESOFMI ST-ELEVATION MI (STEMI) NON ST-ELEVATION MI (NSTEMI) AND
- 45. ST-SEGMENT Localizing MI Look at ST changes, Q wave in all leads. Grouping the leads into anatomical location,we Ischemic change can be attributed to differentcoronary arteries supplying the area. Location of MI Lead with ST changes Affected coronary artery Anterior V1, V2, V3, V4 LAD Septum V1, V2 LAD left lateral I, aVL, V5, V6 Left circumflex inferior II, III, aVF RCA Right atrium aVR, V1 RCA *Posterior Posterior chest leads RCA *Right ventricle Right sided leads RCA * T ohelp identify MI, right sided andposterior leads can beapplied haveI.this: II. III. aVR V1 aVL V2 aVF V3 V4 V5 V6 (LAD)
- 46. ST SEGMENT ST-ELEVA TIONMI(STEMI) 0 HOUR • Pronounced TWave • STelevation (convextype) 1-24H • Depressed RWave, and Pronounced TWave • Pathological Qwaves may appear within hours or may take greater than 24hr indicating full- thickness MI. • Qwave is pathological if it is wider than 40 ms or deeper than athird of the height of the entire QRScomplex Day 1-2 • Exaggeration of TWave continues for24h Days later • TWave inverts asthe STelevation begins toresolve • Persistent STelevation is rare except in the presenceof a ventricular aneurysm Weeks later • ECG returns to normal T wave, but retains pronounced Q wave • An old infarct may look likethis
- 47. I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 Inferior MI ST SEGMENT How about thisone?
- 48. ST SEGMENT NONST-ELEVA TIONMI (NSTEMI) • NSTEMIis also known assubendocardial or non Q-wave MI • In apt with Acute Coronary Syndrome (ACS)in which the ECGdoes not show ST elevation, NSTEMI(subendocardial MI)is suspected if • ST Depression (A) • T wave inversion with or without ST depression (B) • Q wave and ST elevation will never happen To confirm a NSTEMI, do Troponin test: • If positive: NSTEMI • If negative: Unstable angina
- 49. ST SEGMENT NONST-ELEVA TIONMI (NSTEMI) • N-STEMI:acute coronary syndrome (with troponin increase) • Arrows indicate ischemic STsegmentchanges. • Without appropriate treatment in many cases STEMIinfarction will occur
- 50. MYOCARDIALISCHEMIA • 1mmST-segmentdepression • Symmetrical • Tall Twave • Long QT-interval • STdepression ismore suggestive of myocardialischemia than infarction ST SEGMENT
- 51. T wave • Twave is the positivedeflection after each QRScomplex • It representsventricular repolarisation • Upright in all leads except aVR and V1 • Amplitude – <5mm in limb leads – <15mmin precordial leads
- 52. Step 7: QT- INTERVAL
- 53. QT- INTERVAL • QTinterval decreases when heart rate increases • Asageneral guide theQTinterval shouldbe 0.35- 0.45 s,(<2 large square) and shouldnot be more than half of the interval between adjacent Rwaves(R-R interval) < 2 large square
- 54. T-WAVE Normal T wave • Asymmetrical, the first half having more gradual slope than the secondhalf • >1/8and <2/3 of the amplitude of corresponding Rwave Amplitude rarely exceeds10mm • Abnormal Twaves are symmetrical, tall, peaked, biphasic, or inverted LONGQT SYNDROME • LQTis a rare inborn heart condition in which repolarization of the heart is delayed following aheartbeat • Example: Jervell and Lange-Nielsen Syndrome or Romano-WardSyndrome
- 55. STEP 8: CARDIAC AXIS
- 56. CARDIAC AXIS • Todetermine cardiac axis look at QRScomplexes of lead I , II, III. Axis Lead I Lead II Lead III Normal Positive Positive Positive/Negative Right axis. deviation Negative Positive Positive Left axis deviation Positive Negative Negative • Remember, positive(upgoing) QRScomplex means theimpulse travels towards thelead. • Negative means movingaway
- 60. I (0º) I I aVF aVF (+90º) (180º) NORMAL AXIS LEFT AXIS DEVIATION RIGHT AXIS DEVIATION EXTREME RIGHT AXIS DEVIATION I aVF I aVF
- 61. Cardiac Axis Causes Left axis deviation Normal variation in pregnancy, obesity; Ascites, abdominal distention, tumour; left anterior hemiblock, leftventricular hypertrophy, QWolff- Parkinson-White syndrome, Inferior MI Right axis deviation Normal finding in children and tall thin adults, chronic lung disease(COPD), left posterior hemiblock, Wolff-Parkinson-White syndrome, anterolateral MI North West Emphysema, hyperkalaemia. leadtransposition, artificial cardiac pacing, ventriculartachycardia CARDIACAXIS
- 62. STEP 9: OTHER ECG SIGNS
- 63. LEFT VENTRICULAR HYPERTROPHY RIGHT VENTRICULAR HYPERTROPHY AND So, we have to start looking at the S waves and R waves
- 64. Left ventricular hypertrophy (LVH) Criteria: Example: • Todetermine LVH,use one of the following: Sokolow & Lyon Criteria: S (V1) + R(V5 or V6) > 35mm Cornell Criteria: S (V3) + R (aVL) > 28 mm (men) or > 20 mm (women) Others: R (aVL) > 13mm S (V1) + R(V5) = 15 + 25 = 40mm S(V3) + R (aVL)= 15 + 14 =29mm R(aVL) =14 mm LVH!
- 65. • Tall Rwaves in V4and V5with down sloping STsegment depression and Twave inversion are suggestive of left ventricular hypertrophy (LVH) with strain pattern • LVHwith strain pattern usually occurs in pressure overload of the left ventricle as in systemic hypertension or aortic stenosis Let’s see another example of LVH LVH strain pattern
- 66. Right ventricular hypertrophy (RVH) Example: Right axis deviation (QRS axis >100o) V1(R>S), V6 (S>R) Right ventricular strain T waveinversion So, it’s RVH!
- 67. CommonCausesof LVHand RVH LVH RVH • Hypertension (most common cause) Aortic stenosis • Aortic regurgitation Mitral regurgitation • Coarctation of theaorta • Hypertrophic cardiomyopathy • Pulmonary hypertension • Tetralogy of Fallot • Pulmonary valve stenosis • Ventricular septal defect(VSD) • High altitude • Cardiac fibrosis COPD • Athletic heart syndrome
- 68. • Narrow and tall peaked Twave (A) is an early sign PRinterval becomes longer • Pwave loses its amplitude and may disappear QRScomplex widens(B) • When hyperkalemia is very severe, the widened QRScomplexes merge with their • corresponding Twaves and the resultant ECGlooks like a series of sine waves (C) • If untreated, the heart arrests in asystole HYPOKALAEMIA • Twave becomes flattened together with appearance of a prominent U wave • The STsegment may become depressed and the Twaveinverted • These additional changes are not related to the degree of hypokalemia HYPERKALAEMIA
- 69. E C G RULES • ProfessorChamberlains10 rules of a normal ECG,afoundation to ECG interpretation usedall over the world to this date
- 70. 10RULESOFA NORMALECG Rule1 PRIshould be 120to 200ms (3 to 5smallsquares) Rule2 QRScomplex width should not exceed 120ms(<3 smallsquares) Rule3 QRScomplex should be Rule4 QRSand Twaves tend to have dominantly uprightin lead 1and the samedirection in the limb II leads Rule5 All waves are negative in lead Rule6 Rwave must grow from V1tov4 AVR and Swave must grow from V1toV3 and disappear inV6 Rule7 STsegment shouldstart Rule8 Pwaves should be upright inI,II isoelectric except V1andV2 and V2to V6 (maybe elevated) Rule9 No Qwave or only asmall q wave (<0.04 in width) in I,II,V2 to V6 Rule10 Twave must be upright in 1,II,V2- V6
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