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Amanda Hooper2008-2009EKG for ACLS1Lets start with some basics

V1: right 4th intercostal spaceV2: left 4th intercostal spaceV3: halfway between V2 and V4V4: left 5th intercostal space, mid-clavicular lineV5: horizontal to V4, anterior axillary lineV6: horizontal to V5, mid-axillar line

2Conduction 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 60-100 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.

3EKG PaperEKG machine moves at 25 mm/sec, each small box is 1 mmSmall boxes represent 0.04 secLarge boxes represent 0.2 secFive large boxes equal one second

4EKG Waves and IntervalsP wave: the sequential activation (depolarization) of the right and left atriaQRS complex: right and left ventricular depolarization (normally the ventricles are activated simultaneously)ST-T wave: ventricular repolarizationPR interval: time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex)QRS duration: duration of ventricular muscle depolarizationQT interval: duration of ventricular depolarization and repolarization

5Systematic Approach to ECG InterpretationRateRhythmAxisIntervalsHypertrophyInfarct (QRST Changes)

For acls only need to do rate, rhythm, and intervals on a rhythm strip

6Determining RateR-R interval is ventricular ratep-p interval is atrial rate. Usually the same but not always

Several ways to do this1) 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 ~130-140 bpm2) Count the number of large boxes and divide by 300Ex: 300/2 = 150 but it is a little slower than that so we might say ~130-140 bpm3) Count the number of small boxes between beats and divide into 1500Ex: 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

7Analyzing A Rhythm StripIs 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.8IntervalsPR interval From the onset of atrial depolarization to the onset of ventricular depolarizationNormal between 0.12 and 0.20 secso should be less than a large boxQRS interval:Time it takes for ventricular depolarization to occurNormal is 0.10 sec or lessso should be less than half of a large boxQT intervalFrom the beginning of ventricular depolarization to the end of ventricular repolarizationNormal is les than half of a R-R interval (cant always rely on this if rate is very tachycardic)

Prolonged QT interval- drugs, lytes, CNS9

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

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14Atrial Flutter with 2:1 AV Block

Magically atrial rate is almost always 300, and with 2:1 AV conduction the ventricular rate almost always 15015Aflutter With Carotid Massage

16Supraventricular 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 rhythm17SVT

No p waves, regular18

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PS dont forget PEA- any rhythm without a pulse!22

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26Myocardial InfarctionLook for QRST changes in each lead Note each lead where Q waves are foundLook for R wave progressiontransition normally occurs between V2 and V4Look 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 possible27Basic Lead GroupingsInferior leads: II, III, aVFLateral (left-sided) leads: V4 to V6 and I, aVLSeptal leads: V1, V2Anterior leads: V2 to V4

Right coronary artery:SA node, IV septum, inferior heart, +/- posterior heartLeft coronary artery:LAD- anterior heartLeft circumflex- lateral heart

2812 EKG with Acute MI

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Anteroseptal MI30Inferior MI with RV Infarction

From: Heart Disease 6th Edition. Braunwald E, Zipes D, and Libby P. 200131