Ecg Part 1

ECG diagnosis

Lead Position
A typical ECG report shows the cardiac cycle from 12 different vantage points (I, II, III, aVR, aVL, aVF, V1-V6), like viewing the event electrically from 12 different locations (like a 3D perspective).BUT only 10 electrodes are used.
Lead I represents activity that is going from the right arm to the left arm
Lead II represents activity that is going from the right arm to the left leg
Lead III represents activity that is going from the left arm to the left leg
aVL is placed on the left arm (or shoulder)
aVF is placed on the left leg (or hip)
aVR is placed on the right arm (or shoulder)
V1- 4th intercostal space to the right of sternum
V2- 4th intercostal space to the left of sternum
V3- halfway between V2 and V4
V4- 5th intercostal space in the left mid-clavicular line
V5- 5th intercostal space in the left anterior axillary line
V6- 5th intercostal space in the left mid axillary line

Aims
10 ECG rules
Heart Rate
ECG signs of M.I.
Evolution of changes in M.I.
Classical Appearences

QRS waveform nomenclature R r qR qRs Qrs QS Qr Rs rS qs rSr’ rSR’

The 10 rules for a normal ECG .2 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Rule 1 Millivolts Milliseconds 0 200 400 600 -0.5 0 0.5 1.0 P R T Q S PR interval should be 120 to 200 milliseconds or 3 to 5 little squares PR interval

Rule 2 Millivolts Milliseconds 0 200 400 600 -0.5 0 0.5 1.0 QRS The width of the QRS complex should not exceed 110 ms, less than 3 little squares P R T Q S

Rule 3 The QRS complex should be dominantly upright in leads I and II I II III aVR aVL aVF

Rule 4 QRS and T waves tend to have the same general direction in the limb leads I II III aVR aVL aVF

Rule 5 All waves are negative in lead aVR P Q T S

Rule 6 V 1 V 2 V 3 V 4 V 5 V 6 The R wave in the precordial leads must grow from V1 to at least V4

Rule 7 The ST segment should start isoelectric except in V1 and V2 where it may be elevated I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Rule 8 The P waves should be upright in I, II, and V2 to V6 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Rule 9 There should be no Q wave or only a small q less than 0.04 seconds in width in I, II, V2 to V6 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Rule 10 The T wave must be upright in I, II, V2 to V6 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

What is the heart rate?
(300 / 6) = 50 bpm
www.uptodate.com

(300 / ~ 4) = ~ 75 bpm
www.uptodate.com

(300 / 1.5) = 200 bpm

10 Second Rule
As most EKGs record 10 seconds of rhythm per page, one can simply count the number of beats present on the EKG and multiply by 6 to get the number of beats per 60 seconds.
This method works well for irregular rhythms.

33 x 6 = 198 bpm
The Alan E. Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/

Characteristic changes in AMI
ST segment elevation over area of damage
ST depression in leads opposite infarction
Pathological Q waves
Reduced R waves
Inverted T waves

ST elevation
Occurs in the early stages
Occurs in the leads facing the infarction
Slight ST elevation may be normal in V 1 or V 2
R P Q ST

Deep Q wave
Only diagnostic change of myocardial infarction
At least 0.04 seconds in duration
Depth of more than 25% of ensuing R wave
R P Q T ST

T wave changes
Late change
Occurs as ST elevation is returning to normal
Apparent in many leads
R P Q T ST

Bundle branch block I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 I II III aVR aVL aVF V1 V2 V3 V4 V5 V6 Anterior wall MI Left bundle branch block

Sequence of changes in evolving AMI 1 minute after onset 1 hour or so after onset A few hours after onset A day or so after onset Later changes A few months after AMI Q R P Q T ST R P Q ST P Q T ST R P S T P Q T ST R P Q T

Anterior infarction Anterior infarction Left anterior descending artery (LAD) I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Inferior infarction Inferior infarction Right coronary Artery( RCA) OR Circumflex (LCX) I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Lateral infarction Lateral infarction Left circumflex coronary Artery OR DAIAGONAL branch of LAD I II III aVR aVL aVF V1 V2 V3 V4 V5 V6

Location of infarct combinations aVR V1 V4 I II III LATERAL OR HIGH LATERAL INFERIOR SEPTAL ANT ANT LAT aVL aVF V2 V3 V5 V6

Diagnostic criteria for AMI
Q wave duration of more than 0.04 seconds
Q wave depth of more than 25% of ensuing r wave
ST elevation in leads facing infarct (or depression in opposite leads)
Deep T wave inversion overlying and adjacent to infarct
Cardiac arrhythmias

Hay….. wake up we are done

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Ecg Part 1

by ihab suliman on Oct 10, 2008

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