Blue Lightning

1
Introduction to EKG for non-EKG Techs
By Adam Arseneault CCT Many Slides Courtesy of
Mícheál P. Macken MD MRCPI And Roneil Malkani
MD
2
The Run Down

• Understanding heart conduction
• Neurological studies of interest
• What rhythms to worry about
• Commonly seen rhythms and conduction
  abnormalities
• Question time

3
Cardiac Conduction
(Marquette Electronics, 1996 )
4
Sinoatrial (SA) Node

• The Sinoatrial Node is the hearts pacemaker
• Found in the wall of the right atrium at the
  junction with the superior vena cava
• Rich vagal and parasympathetic innervation
• Intrinsic range of firing is 60-100 bpm

(French, 2006)
5
Atrioventricular (AV) Node

• Back-up Pacemaker
• Located in the wall of the right atrium next to
  the tricuspid valve
• Responsible for slowing down conduction from the
  atria to the ventricles so atrial contraction can
  occur
• This slowing lets the atria slightly overfill the
  ventricles to increase cardiac output and the
  ventricular pump
• Rich vagal and parasympathetic innervation
• Intrinsic rate is 40-60 bpm

(French, 2006)
6
Bundle of His (AKA HIS Bundle)

• Starts just at the bottom of the AV Node to where
  the Left and Right Bundle Branches fork
• Located in the right atrium and inter-ventricular
  septum
• It is the route of communication between the
  atria and ventricles
• Intrinsic rate of 40-45 bpm

(French, 2006)
7
Right and Left Bundle Branches

• Left Bundle Branches
• Conducts to the left ventricle
• Right Bundle Branch
• Conducts to the right ventricle
• Intrinsic rate is 40-45 bpm

(French, 2006)
8
Purkinje System

• Made up of individual cells just beneath the
  endocardium
• These cells initiate the ventricular
  depolarization cycle
• Located in the ventricles
• Intrinsic rate 20-40 bpm

(French, 2006)
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Cardiac Conduction
(Marquette Electronics, 1996 )
10
Conduction in Motion
11
What is an EKG?

• Basics Waveforms are representations of the
  electrical activity created by depolarization of
  the atria and ventricles
• With an EKG we can measure the rate and
  regularity of heartbeats, as well as the size and
  position of the chambers, the presence of any
  damage to the heart, and the effects of drugs or
  devices used to regulate the heart, such as a
  pacemaker.

12
What is an EKG?

• 12-lead ECG
• - 10 electrodes required to produce 12-lead ECG.
• - Electrodes on all 4 limbs (RA, LA, RL, LL)
• - Electrodes on precordium (V16)
• - Monitors 12 leads (V16), (I, II, III) and
  (aVR, aVF, aVL)
• - Allows interpretation of specific areas of the
  heart
• - Inferior (II, III, aVF)
• - Lateral (I, aVL, V5, V6)
• - Anterior (V14)

13
What is an EKG?
14
What is an EKG?

• P Wave (Atrial Depolarization)
• QRS Complex (Rapid Ventricular Depolarization)
• T Wave (Ventricular Repolarization)

(Wagner, 2006)
15
Depolarization and Repolarization

• Depolarization when a cell membrane's charge
  becomes positive in order to generate an action
  potential. Caused by positive sodium and calcium
  ions going into the cell (concentration gradient)
• Repolarization (re-negative) when a cell
  membrane's charge returns to negative after
  depolarization. Caused by positive potassium ions
  moving out of the cell.

16
What is an EKG?

• 1mm (small square) 40 ms
• 5mm (big square) 200 ms
• Methods for measuring heart rate
• For regular rhythms Rate 300 / number of
  large squares in between each consecutive R wave
• For very fast rhythms Rate 1500 / number of
  small squares in between each consecutive R wave
• For slow or irregular rhythms Rate number of
  complexes on the rhythm strip x 6 (this gives
  the average rate over a ten-second period)

17
What is an EKG?

• PR Interval
• QRS Interval
• QT Interval

18
Interval Norms
19
P-Wave

• PR Interval
• Time from beginning of the P wave to the
  beginning of the QRS complex (onset of
  ventricular depolarization) Normal range is from
  120 ms 200 ms
• Atrial contraction begins in the middle of the P
  wave and continues throughout the PR interval
• Corresponds to the delay necessary for the
  ventricles to fill after atrial contraction
• The atrial repolarization wave (electrical
  impulse) is usually hidden by the QRS complex

20
QRS Complex

• Time it takes for the depolarization of the
  ventricles
• Norms 40 ms to 120 ms measured from the initial
  deflection of the QRS from the isoelectric line
  to the end of the QRS complex.
• R-wave point when half of the ventricular
  myocardium has been depolarized
• RS line activation of the posteriobasal portion
  of the ventricles

21
Ventricular Depolarization

• Ventricular depolarization requires normal
  function of the right and left bundle branches. A
  block in either the right or left bundle branch
  delays depolarization of the ventricles,
  resulting in widening QRS
• Ventricular contraction begins at about half-way
  through the QRS complex and continues to the end
  of the T-wave.
• Pumping of blood begins when ventricular pressure
  exceeds aortic pressure, causing the semi lunar
  valves to open. This is normally at the end of
  the QRS complex and start of ST segment.

(Molson Medical Informatics Project, 2000)
22
ST Segment

• Period from the end of ventricular depolarization
  to the beginning of ventricular repolarization
• Although the ST segment is isoelectric, the
  ventricles are actually contracting
• Elevated or depressed is a hallmark sign of
  ischemia, CAD or impending MI (STEMI)
• Norm 80 ms to 120 ms

(Molson Medical Informatics Project, 2000)
23
QT Interval

• Normally 340 ms to 430 ms
• Measure from the beginning of the Q wave to the
  end of the T wave
• Represents the total duration of electrical
  activity of the ventricles
• Prolonged QT is associated with an increased risk
  of ventricular arrhythmias, especially torsades
  de pointes
• QTc is prolonged if gt 440ms in men or gt 460ms in
  women
• QTc gt 500 is associated with increased risk of
  torsades de pointes
• QTc is abnormally short if lt 350ms
• A useful rule of thumb is that a normal QT is
  less than half the preceding RR interval

24
T Wave

• Corresponds to the rapid ventricular
  repolarization
• Normally rounded and positive
• Most labile wave in the EKG

25
U Wave

• Thought to represent repolarization of the
  purkinje fibers
• Not always seen
• Prominent U waves are most often seen in
  hypokalemia, but may be present in hypercalcemia,
  thyrotoxicosis, or exposure to digitalis, or
  epinephrine

26
Telemetry Monitoring

• Rate per minute
• Examine R to R regularity
• Check P waves
• Measure PR Interval
• Determine if each P wave is followed by a QRS
  complex
• Examine the QRS
• Examine the QT Interval

(Wagner, 2006)
27
Normal Cardiac Rhythm

• Rate 60-100 bpm
• Regular rate and rhythm
• PR Interval between 120-200 ms
• QRS Interval between 40-120 ms
• QT Interval between 340-430 ms

28
Sinus Rhythm

• Rate 60-100 bpm
• Regularity Regular
• P-Waves Regular and 11 ratio with QRS
• PR Interval PR 120-200 ms

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Sinus Bradycardia

• Rate lt60 bpm
• Regularity Regular
• P-Waves Regular and 11 ratio with QRS
• PR Interval PR 120-200 ms

30
Sinus Tachycardia

• Rate gt100 bpm usually under 170 bpm
• Regularity Regular
• P-Waves Regular and 11 ratio with QRS
• PR Interval PR 120-200 ms

31
Sinus Arrhythmia

• Rate Any sinus rate
• Regularity Irregular
• P-Waves Regular and 11 ratio with QRS
• PR Interval PR 120-200 ms

32
EKG Abnormalities During Partial Seizures in
Refractory Epilepsy

• Fifty-one seizures in 43 patients with
  intractable partial epilepsy
• Cardiac rhythm and conduction abnormalities are
  common during seizures, particularly if they are
  prolonged or generalized, in intractable
  epilepsy. These abnormalities may contribute to
  SUDEP.

Nei et al, Epilepsia, 2000
33
EEG and ECG in Sudden Unexplained Death in
Epilepsy

• 21 patients with SUDEP compared with previous
  study of 43 patients with refractory partial
  epilepsy studied ECG changes
• Ictal max HR was significantly higher in SUDEP
  patients than in controls (mean 149 bpm vs 126
  bpm)
• Ictal cardiac repolarization or rhythm
  abnormalities 56 in SUDEP vs 39 in controls
  not significant

Nei et al, Epilepsia, 2004
34

• Ictal asystole (IA) preventable cause of sudden
  unexplained death in Epilepsy
• Compared heart rate (HR) characteristics of IA
  patients to a group of patients with vasovagal
  (benign, not seizure-related) asystole.
• IA was seen in 8 patients, all with temporal lobe
  epilepsy.
• No statistical difference was found in
• duration of asystole, bradycardia, and baseline
  HR characteristics
• Only significant difference higher HR
  acceleration post-asystole in the controls.

Schuele et al, Epilepsia, 2008
35
Arrhythmias Encountered in Neurological
Conditions (Stroke, Seizures, etc.)

• Atrial
• Bradycardia
• Supraventricular tachycardias
• Atrial flutter
• Atrial fibrillation

• Ventricular
• Ectopic ventricular beats
• Multifocal ventricular tachycardias
• Torsades de pointes
• Ventricular fibrillation

36
Possible Mechanisms

• Altered parasympathetic/vagal activity
• Altered sympathetic activity
• Imbalance between these two arms of the autonomic
  nervous system
• Increased circulating catecolamines

37
Premature Atrial Contractions

• These complexes originate in the atria
• They often originate from ectopic pacemaker sites
  within the atria which results in an abnormal P
  wave
• The complex occurs before the normal beat is
  expected, and followed by a pause

38
Premature Atrial Contractions

• Rate Underlying rhythm
• Regularity Irregular with PAC's Compensatory
  Pause
• P-Waves Ectopic P-wave Differs from Sinus P
  wave
• PR Interval Differs from underlying Sinus P wave

39
Supraventricular Tachycardia

• Regularity Regular
• Rate 140 220 bpm
• P-Waves Usually blocked by preceding T wave
• QRS Generally normal
• Usually starts and stops suddenly

40
Atrial Flutter

• Rate Atrial 240-440 bpm Ventricular varies
• Regularity Atrial rate regular Ventricular rate
  from 21 to 81
• Atrial flutter is characterized by "sawtooth"
  atrial activity and a conduction ratio to the
  ventricles of 21 to 81
• Caused by a reentry circuit located in the right
  atrium
• Check patients cardiac history, if any

41
Atrial Fibrillation

• Rate Can vary
• Regularity Irregular
• P-Waves No discernible P-wave present
• This is the most common sustained cardiac
  arrhythmia
• Characterized by an undulating baseline
  replacing P waves and an irregularly irregular
  ventricular response
• Check patients cardiac history, if any

42
Premature Ventricular Contraction

• A PVC is a depolarization that arises in either
  ventricle before the next expected sinus beat
  altering the normal sequence of depolarization
• The two ventricles depolarize sequentially
  instead of simultaneously
• Conduction moves slowly and this results in a
  widened QRS complex (greater than 120 ms)
• Three or more PVC's in a row is considered a run
  of Ventricular Tachycardia
• If it lasts for more than 30 seconds it is
  designated sustained VT

(French, 2006)
43
Premature Ventricular Contraction

• Rate Underlying rhythm
• Regularity Irregular
• P-Waves Underlying rhythm
• PR Interval Underlying rhythm
• QRS Severely different from other beats, gt120 ms

44
Ventricular Tachycardia

• Rate gt100 bpm to lt220 bpm
• Regularity Generally Regular Can be Irregular
• QRS Interval gt120 ms
• Treatment If patient is sleeping wake them up
  and see if they are responsive and whether rhythm
  terminates. Also check whether pt. has AICD
• If neither call Code!

45
Torsades de Pointes
46
Torsades de Pointes

• Polymorphic ventricular tachycardia (PVT) is a
  form of ventricular tachycardia in which there
  are multiple ventricular foci with the resultant
  QRS complexes varying in amplitude, axis and
  duration. The most common cause of PVT is
  myocardial ischaemia.
• Torsades de pointes (TdP) is a specific form of
  polymorphic ventricular tachycardia occurring in
  the context of QT prolongation it has a
  characteristic morphology in which the QRS
  complexes twist around the isoelectric line.
• For TdP to be diagnosed, the patient has to have
  evidence of both PVT and QT prolongation.

47
Ventricular Fibrillation

• Rate Very Rapid too unorganized to count
• Regularity Irregular No normal QRS Waveform
  varies in size and shape No P-waves No T-waves
• Treatment is always immediate unsynchronized
  defibrillation

48
Ventricular Fibrillation

• Ventricular Fibrillation is a rhythm in which
  multiple areas within the ventricles are
  erratically depolarizing and repolarizing
• There is no organized depolarization, therefore
  the ventricles do not contract as a unit
• The myocardium is quivering - There is no cardiac
  output
• This is the most common arrhythmia seen in
  cardiac arrest from ischemia or infarction.
• The rhythm is described as coarse or fine VF.
  Coarse VF indicates recent onset of VF. Prolonged
  delay without defibrillation results in fine VF
  and eventually asystole
• Treatment is always immediate unsynchronized
  defibrillation

49
Asystole

• No Conduction
• Asystole represents the total absence of
  ventricular electrical activity
• Since depolarization does not occur, there is no
  ventricular contraction
• This may occur as a primary event in cardiac
  arrest, or it may follow VF or pulseless
  electrical activity (PEA).
• Treatment Immediate

50
Transient Asystole

• Asystole can also be transient, a few seconds up
  to 1 minute or longer, due to vagal hyperactivity
• Sleep apnea/Snoring during sleep
• Valsalva maneuver
• During seizures Ictal asystole
• Medullary centers in brainstrem
• Valsalva reflex
• Other causes

51
Ancillary Information

• Junctional Rhythms/beats
• AV Blocks
• First, Mobitz I and II, Third degree
• WPW
• Brugada
• Electronic Pacer

52
Junctional Escape Rhythm

• Rate 40-60 bpm
• Regularity Regular
• P-Waves They will be inverted, and may appear
  before or after the QRS complex, or they may be
  absent, hidden by the QRS
• PR Interval If Present PR lt120 ms

53
Premature Junctional Contraction

• Rate Underlying rhythm
• Regularity Irregular
• P-Waves They will be inverted, and may appear
  before or after the QRS complex, or they may be
  absent, hidden by the QRS
• PR Interval If Present PR lt120 ms

54
First Degree AV-Block

• Regularity Regular
• Rate Underlying rhythm
• P-Waves Regular and 11 ratio with QRS
• PR Interval Constant and prolonged PR Interval,
  gt0.20 sec

55
Second Degree AV-Block Type 1Wenckebach

• Regularity Irregular
• Rate Underlying rhythm
• P-Waves Regular
• PR Interval PR gradually elongates until a
  dropped beat which leads to a reset
• This is usually benign and due to increased vagal
  activity

56
Second Degree AV-Block Mobitz Type 2

• Rate Underlying rhythm
• Regularity Irregular
• P-Waves Regular
• PR Interval P-waves march but not all conducted
• This block is bad because it originates below the
  AV node, the escape rhythm is too slow
• Treatment is a pacemaker

57
Third Degree AV-Block Complete Heart Block

• Rate Underlying rhythm
• P-Waves Regular but not related to QRS
• A total lack of conduction through the AV node
• This conduction defect is dangerous and may
  progress to ventricular standstill
• Treatment is an artificial pacemaker

58
Wolff-Parkinson-White Syndrome

• Short PR interval (lt 120ms)
• Broad QRS (gt 100ms)
• A slurred upstroke to the QRS complex (the delta
  wave)
• Pre-excitation refers to early activation of the
  ventricles due to impulses bypassing the AV node
  via an accessory pathway
• In WPW the accessory pathway is often referred to
  as the Bundle of Kent, or atrioventricular bypass
  tract
• Can cause tachyarrhythmia

Lifeinthefastlane.com
59
Wolff-Parkinson-White Syndrome
Bundle of Kent
Accessory Pathway
60
Brugada Syndrome

• Note the pattern resembling a right bundle
  branch block, the P-R prolongation and the ST
  elevation in leads V1-V3
• Brugada is a recently found arrhythmia that can
  lead to ventricular fibrillation, also may be
  inherited.

Brugada.org
61
Pacemaker Rhythms

• If a patient has a pacemaker you may see spikes
  representing the electrical activity from the
  pacemaker
• You could see a spike preceding a wide QRS when
  ventricular pacing
• Or a spike preceding P wave when atrial pacing

62
Ventricular Pacemaker Rhythm
63
Atrial Pacemaker Rhythm
64
Atrial and Ventricular Pacing
65
Left-sided Brain Hemorrhage Causing ST Segment
Elevation
66
Introduction to EKG for non-EKG Techs
By Adam Arseneault CCT Many Slides Courtesy of
Mícheál P. Macken MD MRCPI And Roneil Malkani
MD