1. EKG for ACLS
Amanda Hooper

2. Let’s start with some basics…
V1: right 4th intercostal space
V2: left 4th intercostal space
V3: halfway between V2 and V4
V4: left 5th intercostal space, mid-clavicular line
V5: horizontal to V4, anterior axillary line
V6: horizontal to V5, mid-axillar line

3. Conduction System of the Heart
Sinus node is the pacemaker of the heart, the dominant center of automaticity.
Generates continuous regular depolarization stimuli at a rate of bpm
There are other potential pacemakers that can take over if SA node fails, and they have different intrinsic rates. These are in the atria, AV junction, and the ventricles.

4. EKG Paper EKG machine moves at 25 mm/sec, each small box is 1 mm
Small boxes represent 0.04 sec
Large boxes represent 0.2 sec
Five large boxes equal one second

5. EKG Waves and Intervals
P wave: the sequential activation (depolarization) of the right and left atria
QRS complex: right and left ventricular depolarization (normally the ventricles are activated simultaneously)
ST-T wave: ventricular repolarization
PR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex)
QRS duration: duration of ventricular muscle depolarization
QT interval: duration of ventricular depolarization and repolarization

6. Systematic Approach to ECG Interpretation
Rate
Rhythm
Axis
Intervals
Hypertrophy
Infarct (QRST Changes)
For acls only need to do rate, rhythm, and intervals on a rhythm strip

7. Determining Rate R-R interval is ventricular rate
p-p interval is atrial rate. Usually the same but not always
Several ways to do this…
1) Count down the number of large boxes: 300, 150, 100, 75, 60, 50, ....
Ex: this one is between 150 and 100, closer to 150 so we might say ~ bpm
2) Count the number of large boxes and divide by 300
Ex: 300/2 = 150 but it is a little slower than that so we might say ~ bpm
3) Count the number of small boxes between beats and divide into 1500
Ex: 1500/11 = 136 bpm
If QRS occurs at each large box then R-R interval is 0.2 seconds, then rate is 300 bpm (5 beats/second x 60sec/min)
25 small boxes/sec x 60 sec/min = 1500

8. Analyzing A Rhythm Strip
Is the rhythm regular?
What is the rate?
Is the QRS complex narrow or wide?
Are P waves present?
Are P waves related to the QRS complexes?
What is the PR interval ?
Rhythm= mind your Ps, Qs and the 3 Rs (p waves, QRS complexes, rate, regularity, relatedness)
If QRS is narrow, almost certain that the impulse is arising at or above the AV node.

9. Intervals PR interval QRS interval: QT interval
From the onset of atrial depolarization to the onset of ventricular depolarization
Normal between 0.12 and 0.20 sec—so should be less than a large box
QRS interval:
Time it takes for ventricular depolarization to occur
Normal is 0.10 sec or less—so should be less than half of a large box
QT interval
From the beginning of ventricular depolarization to the end of ventricular repolarization
Normal is les than half of a R-R interval (can’t always rely on this if rate is very tachycardic)
Prolonged QT interval- drugs, lytes, CNS

10. Sinus tachycardia and sinus bradycardia if all these conditions met but rate is faster or slower, respectively. May be physiologic or not.

15. Atrial Flutter with 2:1 AV Block
Magically atrial rate is almost always 300, and with 2:1 AV conduction the ventricular rate almost always 150

16. Aflutter With Carotid Massage

17. Supraventricular Tachycardia (SVT)
Supraventricular rhythms start by definition at or above the AV node. If the QRS is narrow in all leads, you can almost be guaranteed the rhythm is supraventricular.
Sinus rhythm, atrial fibrillation, atrial flutter, junctional/nodal rhythms, and PSVT
PSVT is a reentry rhythm

18. SVT
No p waves, regular

22. PS don’t forget PEA- any rhythm without a pulse!

27. Myocardial Infarction
Look for QRST changes in each lead
Note each lead where Q waves are found
Look for R wave progression—transition normally occurs between V2 and V4
Look at ST segments and note depression or elevation
Look for T wave inversion
Q waves or T wave inversion may be a normal finding in leads III, aVF, aVL, aVR, and V1
Always consider clinical scenario and compare with old EKG if possible

28. Basic Lead Groupings Inferior leads: II, III, aVF
Lateral (left-sided) leads: V4 to V6 and I, aVL
Septal leads: V1, V2
Anterior leads: V2 to V4
Right coronary artery:
SA node, IV septum, inferior heart, +/- posterior heart
Left coronary artery:
LAD- anterior heart
Left circumflex- lateral heart

29. 12 EKG with Acute MI

30. Anteroseptal MI

31. Inferior MI with RV Infarction
From: Heart Disease 6th Edition. Braunwald E, Zipes D, and Libby P. 2001