ECG introduction

1
12 Lead ECG
2
Objectives

• Fundamental review
• Importance of the EMS 12 lead
• Identify the 3 Is
• Identify the presence of the ST segment
  elevation, depression and pathologic Q wave on 12
  lead ECG.

3
Fundamentals

• SA node
• Impulse formation is initiated
• Dominant pacemaker of the heart.
• 55 population supplied by RCA, 45 by LCA

4
Fundamentals

• Internodal Pathways
• Carry the impulse from the SA node to the AV node

5
Fundamentals

• AV Junction
• This tissue acts as an escape pacemaker ...if the
  SA and Atrial tissues fail.
• The inherent rate of the AV junction is 45-55
  beats per minute.

6
Fundamentals

• AV node
• Protects the ventricles from
• run away atrial rates and delays conduction
  allowing for ventricular filling time.
• Heavy vagal(parasympathetic) innervation .
• Receives oxygenated blood from the RCA

7
Fundamentals

• Bundle Branches
• Right and Left bundle branches..
• Escape pacemakers are slow (20-30 bpm) and
  unreliable.
• The bundle branches receive virtually all their
  oxygenated blood from the LCA.

8
Fundamentals

• Purkinje fibers
• The bundles divides numerous times into the
  Purkinje fibers.
• Final pathways of conduction to the ventricles

9
Patient Position

• Patient positioning important
• Preference to hospitals flat
• Different positions cause 12 lead changes
• Include the patient position in your report
• Note patients position on the 12 lead also

10
Indications for a 12 Lead

• 1. Chest Pain
• Unrelieved by Nitroglycerin
• Lasting greater than 30 minutes.
• 2. ST Segment elevation
• Greater than 1mm in 2 or more adjacent leads.

11
EMS 12 Leads

• Serial 12 Leads are needed to
• Follow the progression of the AMI and/or
  effective treatment
• The hospital will repeat the 12 lead ECG on the
  patients arrival.

12
Additional 12 Leads and Code Summary

• Following the initial 12 Lead.
• Leave the leads connected
• If chest pain changes in intensity
• Repeat 12 Lead
• Following arrival at the hospital or AMR, run a
  Code Summary and give to the receiving
  personnel.
• When possible enter information before 12 lead
  transmission

13
The ECG signs of Infarct!

• Abnormal Q waves
• ST segment elevation
• Inverted T waves
• Indicative changes that occur in an MI/ACS

14
EMS 12 Lead

• Limb Leads
• I,II,III,
• AVR,AVL,AVF
• Chest Leads
• V1-V6

15
QRS

• Q wave
• Negative deflection preceding an R wave
• R Wave
• First positive deflection
• S Wave
• Negative deflection following an R wave

16
Q Wave

• Normal (physiologic) or due to pathology
  (pathologic).
• Depth and width are determining criteria
• Q wave gt0.04 (40 ms) wide is considered a
  significant finding (pathologic)

17
ST Segment

• The segment immediately following the QRS
  complex and ending at the T wave.
• The J point (junction point) is the exact point
  where the QRS stops and the ST begins.

18
ST Segment

• The ST segment is normally level with the T-P
  segment rather than the PR segment
• Examine every lead for ST segment elevation of 1
  mm or more.

19
ST

• St segment elevation of 1 mm or more in two
  anatomically contiguous leads is considered
  evidence of infarction in progress!
• (leads looking at adjoining portions of the heart)

20
Left Ventricle

• Anterior
• Septal
  Lateral
  
  
• Inferior

Posterior
21
Coronary Arteries

• Left Main Coronary Artery - Left Anterior
  Descending Artery (LAD) - Circumflex Artery
  (CX)
• Right Coronary Artery (RCA)

22
Left Coronary Artery

• Supplies blood to
• septum, the bundle branches and the left
  ventricle through the LAD and CX..

23
Right Coronary Artery

• Supplies blood to Right Ventricle
• Through Posterior descending branch supplies
  blood to inferior and posterior of L. ventricle

24
Coronary Arteries

• Can be variations in areas of heart supplied by
  Left and Right CoronaryArteries
• Conduction system blood supply
• SA and AV nodes, Bundle of HIS and Bundle
  Branches

25
Precordial Septal Leads

• V1 V2 Look at the Septum of the heart The
  septal branch of the LAD supplies blood to
  the septum Septum contains the bundle of HIS
  and the bundle branches Occlusions in
  this branch produce
• 2?Type II heart block, 3? heart blocks.

26
Precordial Septal Leads V1 - V2
27
Precordial Anterior Leads

• V3 V4 Look at the anterior wall of the left
  ventricle The LAD (diagonal branch) supplies
  this area Occlusions can lead to LV
  dysfunction
• CHF
• Cardiogenic Shock

28
Precordial AnteriorLeads V3 - V4
29
Anterior-Septal Terminology
30
Lateral Precordial Leads

• I,AVL,V5 V6 Faces lateral of the left
  ventricle The circumflex supplies this area
  AV nodal blocks can occur
• Usually occur with other areas of infarct

31
Precordial LateralLeads V5 - V6
32
Limb LeadsII,III,AVF

• II, III and aVF Face the Inferior wall of the
  LV. 90 of population supplied by Posterior
  Descending Branch of the RCA. May not be
  limited to inferior wall 30-50 of people are
  noted to have RV infarctions in the presence of
  infarctions of inferior wall of LV.

33
Limb Leads II, III, aVF
34
V4R Lead changes

• 50 concurrent with changes in Leads I, II, and
  aVF RV damage often presents with hypotension
  Treatment is volume infusions Use of drugs that
  reduce blood return to RV
• Morphine and NTG
• Severe hypotension, use cautiously.

35
Patient Presentation

• Right ventricular infarct
• Inferior MI
• More hypotensive than you would anticipate
• Kussmals Sign (NOT respirations)
• Clear lung sounds
• ST elevation in V4R

36
Posterior AMI

• No leads look at the posterior wall. Marked ST
  depression confined to leads V1 V4
  suggests L.CX artery occlusion
• ST depression is considered reciprocal ECG
  changes in what should be ST elevation for acute
  posterior wall injury.
• These changes indicate Posterior Infarction