1 BY DR. YVONNE KINYANJUI RUGARAMA HOSPITALLEARNING THE EKG BY DR. YVONNE KINYANJUI RUGARAMA HOSPITAL

2 LEARNING SESSIONS - simplifiedIntroduction – Cardiac anatomy, understanding the EKG, Interpreting the rhythm strips. Rhythm i.e. arrhythmias – Irregular rhythms, escape and premature beats, Rapid ectopic rhythms, heart blocks. Axis and hypertrophy – Lt. & Rt. Atrial hypertrophy and Lt. & Rt. Ventricular hypertrophy Myocardial infarction

3 INTRODUCTION TO EKG

4 OBJECTIVES Basic cardiac anatomy and physiology. What is an EKG?Interpreting a rhythm strip.

5 BASIC CARDIAC ANATOMY AND PHYSIOLOGYTHE HEART IS LIKE A CONE THAT HAS FALLEN OVER.

6 BASIC CARDIAC ANATOMY AND PHYSIOLOGY

7 BASIC CARDIAC ANATOMY AND PHYSIOLOGY

8 BASIC CARDIAC ANATOMY AND PHYSIOLOGY

9 BASIC CARDIAC ANATOMY AND PHYSIOLOGY

10 WHAT IS AN EKG? Electrocardiograph – is the instrument that records the electrical activity of the heart. Electrocardiogram (ECG) is the record of that activity.

11 12 lead EKG tracing

12 WHAT IS AN EKG? 2 types of EKGs: single and 12 lead.Can also have ambulatory, resting and stress EKG. The standard EKG is made up of 12 separate leads (chest and limb leads) which are found on 2 planes (horizontal and frontal).

13 LEADS AND PLANES To understand the EKG, we must understand leads and planes. An EKG records information about the waveforms from different views or perspectives. These perspectives are the leads and planes.

14 LEADS Provide a view of the heart’s electrical activity between one positive pole and one negative pole. An imaginary line lies between the two poles and forms the lead’s axis. Limb leads: I, II, III, aVL, aVR, aVF. Chest leads: V1 to V6.

15 LIMB LEADS

16 LIMB LEADS

17 CHEST LEADS

18 LEADS

19 PLANES A cross-sectional perspective of the heart’s electrical activity. 2 planes: Frontal (ant to post view) and Horizontal(superior or inferior view).

20 PLANES

21 WHAT IS AN EKG? The heart’s electrical activity produces currents that radiate through the surrounding tissue to the skin. Electrodes attached to the skin sense those electrical currents and send them to an EKG monitor. The currents are then transformed into waveforms that represent the heart’s depolarization-repolarization cycle.

22 INTERPRETING A RHYTHM STRIPTHE ECG GRID

23 INTERPRETING A RHYTHM STRIP

24 THE P WAVE 1st component of a normal EKG waveform.Represents atrial depolarization. Look especially at: Location Configuration Deflection

25 THE P WAVE A normal P wave: Location: Precedes the QRS complexAmplitude: 2 to 3 mm high Duration: 0.06 to 0.12 seconds Configuration: Usually rounded and upright Deflection: +ve in I, II, aVF, V2. Usually +ve but may vary in III and aVL. –ve in aVR. Biphasic in V1.

26 THE PR INTERVAL Tracks the atrial impulse from the atria through the AVN, Bundle of His and the bundle branches. Look especially at the duration. A normal PR interval: Location: From beginning of the P wave to the beginning of the QRS complex. Duration: 0.12 – 0.20 seconds.

27 THE QRS COMPLEX Follows the P wave.Represents depolarization of the ventricles. Look especially at: Duration Configuration

28 THE QRS COMPLEX A normal QRS complex:Location: Follows the PR interval. Amplitude: 5-30mm high. Duration: seconds Configuration: Consists of the Q wave (1st –ve deflection, R wave (+ve deflection) and the S wave (2nd –ve deflection). Deflection:+ve in I, II, III, aVL, aVF, V4, V5, V6. –ve in aVR, V1, V2, V3.

29 THE ST SEGMENT Represents the end of ventricular depolarization and the start of ventricular repolarization. Look especially at: Deflection

30 THE ST SEGMENT A normal ST segment has:Location: Extends from the end of the S wave to the beginning of the T wave. Deflection: Usually isoelectric.

31 THE T WAVE Represents ventricular relaxation. Look especially at:Amplitude Configuration Deflection

32 THE T WAVE A normal T wave has: Location: follows the S wave.0.5mm in I, II, III and up to 10mm in the chest leads. Configuration: Typically rounded and smooth. Deflection: Usually upright in I, II, V3, V4, V5, V6. Inverted in aVR. Variable in the others.

33 THE QT INTERVAL Measures ventricular depolarization and repolarization. Length varies with heart rate. Look especially at: Duration. A normal QT interval has: Location: from start of QRS to end of T. Duration: Usually 0.36 – 0.44 seconds

34 THE U WAVE Recovery period of the purkinje tissues.Not always present. Look especially at: Configuration A normal U wave has: Location: After the T wave. Configuration: Typically upright and rounded. Deflection: Upright

35 8-STEP METHOD OF RHYTHM STRIP INTERPRETATIONCheck the rhythm Calculate the rate Evaluate the P wave Check out the P to R Now check out the Q to R to S Talk to the T wave On to the QT ... Oh, yes, and don’t forget...

36 ...IN DETAIL Check the rhythm Calculate the rate Evaluate the P waveHow irregular is the rhythm? Is it slightly or markedly irregular? Does the irregularity occur in a pattern? Calculate the rate Evaluate the P wave Are P waves present? Do they all have a normal configuration? Are they all of similar size and shape? Does every P have a QRS?

37 ...IN DETAIL Check out the P to R Now check out the Q to R to SIs the duration a normal 0.12 – 0.20 sec? Is the PR interval constant? Now check out the Q to R to S Is the duration a normal <0.12 sec? Are all QRS’s the same size and shape? Does a QRS appear after every P wave?

38 ...IN DETAIL Talk to the T wave On to the QTAre T waves present? Do they all have a normal shape and normal amplitude? On to the QT Is the duration a normal 0.36 – 0.44 sec? Oh yes, and don’t forget... Check for ectopic beats and other abnormalities. Check the ST segment. Look for the presence of a U wave.

39 ...IN DETAIL Finish by noting your findings, and then interpret them by naming the rhythm strip according to one or all of these findings: Origin of the rhythm Rate xtics Rhythm abnormalities

40 RATE

41 CALCULATING THE RATE 4 methods10 x method (uses a 6 second strip). 1,500 method Sequence method The rate calculator Be mindful of the recording speed (calibration)

42 CALCULATING THE RATE THE 10 X METHODEasiest way. Not as accurate as other methods. Best for irregular rhythms and bradycadias (<60b/m). Ten 6 second strips = 1 min Atrial rate: Number of P’s in 6 second strip multiplied by 10. Ventricular rate: Number of R’s in 6 second strip multiplied by 10.

43 CALCULATING THE RATE 1,500 METHODCan’t be used if heart rate is irregular. Needs MATHS CALCULATION  1500 small squares = 1 min. Count small squares between identical points on 2 consecutive P and R waves to get atrial and ventricular rates respectively by dividing 1500 by that number.

44 CALCULATING THE RATE SEQUENCE METHODFastest and only used with Regular rythms. Requires memorization of a sequence of numbers corresponding to the heavy black vertical lines on the EKG.

45 NOW ON TO THE PRACTICE RHYTHM STRIPS...

46 RHYTHM

47 OBJECTIVES Definition of arrhythmiaHow to tell if a rhythm is regular or irregular Review the heart’s conduction pathway. Classification and discussion of arrhythmias.

48 DEFINITION OF ARRHYTHMIAAn abnormal or irregular rhythm of the heart. A.K.A dysrhythmia

49 ASSESSING RHYTHM Use the For atrial rhythm: measure P-P intervalCaliper method Paper and pencil method. For atrial rhythm: measure P-P interval For ventricular rhythm: measure R-R interval (Or can use Q or S waves) Variations of up to 0.04sec considered normal.

50 RHYTHM

51 INHERENT RATES Sino-atrial node: 60 -100 b/m Atrial foci: 60 – 80 b/mAV junctional foci: 40 – 60 b/m Ventricular foci: 20 – 40 b/m

52 RECOGNIZING A NORMAL SINUS RHYTHMA normal sinus rhythm is the standard against which all other rhythms are compared. Xtics of a normal sinus rhythm (using 8-step method) Atrial and Ventricular rhythms are regular Atrial and Ventricular rates are between 60 – 100b/m and all impulses are conducted to the ventricles P waves are rounded, smooth and upright. And for every P there is a QRS.

53 RECOGNIZING A NORMAL SINUS RHYTHMPR interval is normal (0.12 – 0.20) QRS is of normal duration (<0.12sec) The T wave is upright. The QT is within normal limits (0.36 – 0.44 seconds). No ectopic or aberrant beats are occurring.

54

55 TYPES OF ARRHYTHMIAS Four Categories: 1. Irregular rhythms2. Escape & Premature beats 3. Rapid ectopic rhythms 4. Heart Blocks

56 IRREGULAR RHYTHMS Sinus Arrhythmia Wandering PacemakerAtrial Fibrillation

57 SINUS ARRHYTHMIA Irregular Pacemaking is still from sinus nodeAll P waves are the same QRS and T wave are normal appearing Changes seen during inspiration and expiration

58 WANDERING PACEMAKER Irregular due to pacing from a variety of atrial foci(pacemaking activity wanders from focus to focus) P waves take different shapes If rate is >100, it is called multifocal atrial tachycardia

59 ATRIAL FIBRILLATION Irregularly irregularRapid firing of multiple foci in the atria No single impulse depolarizes the entire atria Only the occasional impulse gets through to the AV node to stimulate the ventricles Ventricular response may produce rapid or slow ventricular rate

60 ESCAPE & PREMATURE BEATSESCAPE BEAT Response to a pause in cardiac activity Atrial escape beat Junctional escape beat Ventricular escape beat PREMATURE BEAT A focus discharging earlier than expected Premature atrial beat Premature junctional beat Premature ventricular contraction

61 ATRIAL ESCAPE BEAT Pause in the SA node Atrial ectopic focus “escapes”Visible pause on ECG P wave looks different QRS the same

62 JUNCTIONAL ESCAPE BEATEscape beat originates in the AV junction No P wave or inverted from retrograde atrial stimulation QRS the same- ventricles still stimulated through ventricular conduction system

63 VENTRICULAR ESCAPE BEATEscape beat originates in a ventricular ectopic focus No P wave Get an enormous QRS complex (slower conduction)

64 NOTE!!! SINUS ARREST – occurs when a sick SAN’s pacemaking activity is suddenly “arrested” and does not send out pacemaking stimuli. After a pause of sinus arrest, a new pacemaking area assumes the pacing responsibility, and forms the escape rhythm. If the junctional and ventricular escape rhythms accelerate above their inherent rates, they become accelerated idio-junctional and accelerated idio-ventricular rhythms.

65 ESCAPE & PREMATURE BEATSESCAPE BEAT Response to a pause in cardiac activity Atrial escape beat Junctional escape beat Ventricular escape beat PREMATURE BEAT A focus discharging earlier than expected Premature atrial beat Premature junctional beat Premature ventricular contraction

66 PREMATURE ATRIAL BEAT From an ectopic focus in the atriaP wave looks different, not from the SA node

67 PREMATURE JUNCTIONAL BEATFrom an ectopic focus in the AV node No P wave or inverted from retrograde atrial stimulation QRS looks the same

68 PREMATURE VENTRICULAR CONTRACTIONFrom ectopic focus in the ventricles Produces pulse beat earlier and usually weaker than normal. Wide QRS (slower conduction) No P wave Usually followed by a compensatory pause.

69 PREMATURE VENTRICULAR CONTRACTION...Interpolated PVCs: sandwiched between the normal beats. Produce no compensatory pause and no disturbance in the rhythm

70 PREMATURE VENTRICULAR CONTRACTION...

71 PREMATURE VENTRICULAR CONTRACTION...Unifocal: Identical PVCs originating from the same focus.

72 PREMATURE VENTRICULAR CONTRACTION...Multifocal: PVCs from different ventricular foci. Appear different.

73 PREMATURE VENTRICULAR CONTRACTION...Multifocal: Considered a dangerous rhythm, especially in patients with recent myocardial infarction Risk of developing ventricular tachycardia is high

74 PREMATURE VENTRICULAR CONTRACTION...Can be numerous, but >6 per minute can be pathologic Can indicate poor coronary blood flow or: Stimulants, meds, hypoxia can set off PVC’s

75 PREMATURE VENTRICULAR CONTRACTION...If coupled with 1 normal cycle, called Ventricular Bigeminy If found in a 2:1 cycle, called Ventricular Trigeminy

76 PREMATURE VENTRICULAR CONTRACTION...VENTRICULAR PARASYSTOLE Dual rhythm caused by 2 pacemakers One is the ventricular ectopic focus which produces PVC like QRS complexes at a generally slow rate. The other is a supraventricular focus (SAN or AV junction). Appear like PVCs coupled to a long series of normal beats.

77 PREMATURE VENTRICULAR CONTRACTION...VENTRICULAR PARASYSTOLE

78 PREMATURE VENTRICULAR CONTRACTION...A single ectopic focus may produce a run of 3-6 PVC’s Considered more serious pathology Is called a “run of ventricular tachycardia” (v. tach) if more than 3 beats

79 PREMATURE VENTRICULAR CONTRACTION...PVC can occur during a T wave Dangerous event Called “R on T”

80 RAPID ECTOPIC RHYTHMS From ectopic focus pacing rapidlySometimes have more than 1 ectopic focus involved.

81 RAPID ECTOPIC RHYTHMS Paroxysmal Tachycardia - 150-250 beats/minFlutter beats/min Fibrillation beats/min ** Dx: If possible, mention rate and location of ectopic focus responsible.

82 PAROXYSMAL (SUDDEN) TACHYCARDIARates of b/m. Usually arises spontaneously from an ectopic focus. Sinus tachycardia (caused by meds, exercise, excitement, shock) not a paroxysmal tachycardia.

83 PAROXYSMAL TACHYCARDIAFirst confirm rate ( b/m) Then determine location of ectopic focus

84 PAROXYSMAL ATRIAL TACHYCARDIAEctopic atrial focus P wave looks different from those before the tachycardia. QRS and T waves preserved

85 PAROXYSMAL ATRIAL TACHYCARDIA WITH BLOCKMore than 1 P wave before QRS P waves small and spiked and upwards in leads II and III Often seen in digitalis toxicity

86 PAROXYSMAL JUNCTIONAL TACHYCARDIARate b/m Ectopic focus from AV junction No P wave or inverted P wave

87 SUPRAVENTRICULAR TACHYCARDIAParoxysmal atrial and junctional tachycardia together are called supraventricular tachycardia Both can look alike on ECG as P wave can merge with T wave and be unidentifiable Both are treated the same, so differentiating not critical

88 PAROXYSMAL VENTRICULAR TACHYCARDIARate b/m Ectopic ventricular focus Atria are still depolarizing, but hard to see P waves (AV Dissociation)

89 PAROXYSMAL VENTRICULAR TACHYCARDIAPresence of Capture and Fusion beats confirms the diagnosis of PVT.

90 PAROXYSMAL VENTRICULAR TACHYCARDIARuns of ventricular tachycardia often signify coronary artery disease or hypoxia

91 TORSADES DE POINTES Form of ventricular tachycardiaQuinidine toxicity is the most common cause

92 FLUTTER Rate Either atrial or ventricular ectopic focus

93 ATRIAL FLUTTER Rapid, identical P wavesDx most often made based on appearance rather than rate. Saw tooth appearance of P waves.

94 VENTRICULAR FLUTTER Rate 250-350Single ventricular ectopic focus firing at a rapid rate Deteriorates into deadly arrhythmias Ventricles contracting 5/sec Blood unable to fill the ventricles, coronary arteries fail to get blood Multiple ventricular ectopic foci try to compensate, turns into ventricular fibrillation

95 VENTRICULAR FLUTTER

96 FIBRILLATION Rate 350-450 b/m Multiple foci rapidly dischargingChambers not contracting, only twitching Waves not distinguishable Can be either atrial or ventricular

97 ATRIAL FIBRILLATION No P waves discernablePebble in water vs rain in water Ventricular rate – use 6 second strip to calculate

98 ATRIAL FIBRILLATION NORMAL RHYTHM FROM SAN ATRIAL FIBRILLATION

99 VENTRICULAR FIBRILLATIONErratic, irregular ECG tracing If you can recognize a pattern, probably not ventricular fibrillation No cardiac pumping, dire emergency

100 HEART BLOCKS SINUS BLOCK AV BLOCK BUNDLE BRANCH BLOCK HEMIBLOCK

101 HEART BLOCKS Electrical blockPrevents or slows electrical stimuli and depolarization One patient may have multiple types of block

102 SINUS BLOCK SA node fails to pace for at least one cycle, then resumesAll P waves look the same May see an escape beat

103 SINUS BLOCK VERSUS SINUS ARREST

104 AV BLOCK AV node slows or stops depolarization of ventriclesGet a prolonged PR interval or a P wave without a QRS Can be 1˚, 2˚, or 3˚

105 FIRST DEGREE AV BLOCK PR interval prolonged – greater than 0.2 secondsRemains consistent with each heart cycle

106 SECOND DEGREE AV BLOCK TYPE 1 – WENCKEBACHPR interval becomes progressively longer, until QRS is dropped (AV node not penetrated)

107 SECOND DEGREE AV BLOCK TYPE 2 – MOBITZ 2PR interval does not become progressively longer, but still see a QRS dropped PR intervals normal before and after dropped QRS. P waves at a normal rate. Often signals a more serious conduction problems Different from sinus block (which lacks a P wave)

108 SECOND DEGREE AV BLOCK Can get a 2:1 AV Mobitz 2 block

109 SECOND DEGREE AV BLOCK Or a 3:1 AV Mobitz 2 block

110 THIRD DEGREE AV BLOCK Complete blockNo atrial impulse reaches the ventricles Ventricles paced independently QRS will either be junctional paced or ventricular Junctional rhythm is 40-60, Ventricular 20-40 Ventricular rate can be so slow that brain does not receive enough blood and patient loses consciousness – Stokes-Adams syndrome

111 THIRD DEGREE AV BLOCK

112 BUNDLE BRANCH BLOCK Right and left bundle branches normally depolarize at the same time During a branch block, one branch depolarizes more slowly – causes 2 “joined QRSs” i.e. 2 out of sync QRSs superimposed.

113 BUNDLE BRANCH BLOCK Get an R and R` QRS is prolonged ≥ 0.12 sec

114 BUNDLE BRANCH BLOCK RIGHT LEFT Look at leads V1 and V2

115 BUNDLE BRANCH BLOCK Left BBB would block hide the presence of a Q waveCannot rely on ECG to diagnose infarction in the presence of left BBB

116 WOLFF – PARKINSON - WHITEAccessory pathway around the AV node Causes apparent shortening of PR interval and prolonged QRS Can get paroxysmal tachycardia

117 NOW FOR MORE PRACTICE...