EKG Rhythm Review

Stephanie Cordwell, BS, NRP

Paramedic Program Director Kennebec Valley Community College

Disclaimer:

I do not have any conflicts of interest or disclaimers*.

*Except…I have about 50 minutes to review a topic that I teach over a semester…

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Course Objectives

Understand the difference between electrical and mechanical cardiac function;

Identify the components of an EKG rhythm strip;

Understand how to interpret 4-lead EKG findings including atrial,

junctional, and ventricular rhythms.

Cardiac cells…

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• Automaticity • Excitability • Conductivity • Contractility

Gail Walraven, Basic Arrhythmias, Seventh Edition ©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Cardiac Function…

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Mechanical Function

Electrical Function

https://theydiffer.com/difference-between-skeletal-and-cardiac-muscle/ Gail Walraven, Basic Arrhythmias, Seventh Edition

©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Mechanical vs. Electrical Function?

6 Gail Walraven, Basic Arrhythmias, Seventh Edition

©2011 by Pearson Education, Inc., Upper Saddle River, NJ https://www.medicalnewstoday.com/articles/258118.php

So…what are we looking for?

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Bledsoe/Porter/Cherry, Essentials of Paramedic

Care, Second Edition Update

© 2011 by Pearson Education, Inc. Upper

Saddle River, New Jersey

The EKG Paper

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EKG Paper – measures time & voltage

Horizontally - time

One small box - 0.04 sec

One large box - 0.20 sec

Vertically - voltage

One large box - 0.5 mV

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The EKG Paper (cont)

Every 3 seconds (15 large boxes) is marked by a vertical line.

This helps when calculating the heart rate.

3 sec 3 sec

Rhythm Interpretation

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Calculating Heart Rates

11 Gail Walraven, Basic Arrhythmias, Seventh Edition

©2011 by Pearson Education, Inc., Upper Saddle River, NJ

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“Normal” Sinus Rhythm Parameters

Rate 60 - 100 bpm

Regularity regular

P waves normal

PR interval 0.12 - 0.20 s

QRS duration 0.04 - 0.12 s

Any deviation from above is sinus tachycardia, sinus bradycardia or a dysrhythmia

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Dysrhythmia Formation

Dysrhythmias can arise from problems in the:

• Sinus node

• Atrial cells

• AV junction/node

• Ventricular cells

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SA Node Problems

SA node depolarizing too slow

Sinus Bradycardia

SA node depolarizing too fast

Sinus Tachycardia

*Sinus Tachycardia may be an appropriate response to stress.

Rate

Regularity

P waves

PR Interval

QRS Duration

30 bpm

Regular

Present & upright

0.12 seconds

0.10 seconds

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Interpretation: Sinus Bradycardia Deviation from NSR? Rate <60 bpm

Rate

Regularity

P waves

PR Interval

QRS Duration

130 bpm

Regular

Present & upright

0.16 seconds

0.08 seconds

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Interpretation: Sinus Tachycardia Deviation from NSR? Rate >100 bpm

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Atrial Cell Problems

A single irritable focus within the atria conducted in a rapid and repetitive fashion

Atrial Flutter

Continuous, disorganized firing from multiple foci in the atria

Atrial Fibrillation

Rate

Regularity

P waves

PR Interval

QRS Duration

Averages 100 bpm

Irregularly irregular

none

none

0.06 seconds

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Interpretation: Atrial Fibrillation Deviation from NSR? Disorganized atrial depolarization; atrial activity is chaotic

Rate

Regularity

P waves

PR Interval

QRS Duration

70 bpm

regular

Flutter waves

none

0.06 seconds

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Interpretation: Atrial Flutter Deviation from NSR? No P waves; re-entry issue, only some impulses are conducted through

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AV Junctional Problems

Continuous, rapid, organized firing due to re-entry circus loop at AV junction

Supraventricular Tachycardia

Impulses originating from the SA node are delayed or blocked at the AV junction/node, disrupting ventricular depolarization

AV Blocks

Rate

Regularity

P waves

PR Interval

QRS Duration

160 bpm

regular

Cannot determine

Cannot determine

0.08 seconds

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Interpretation: Supraventricular Tachycardia

Deviation from NSR? Regular, tachycardic rate, cannot discern P waves

Rate

Regularity

P waves

PR Interval

QRS Duration

60 bpm

regular

normal

0.36 seconds

0.08 seconds

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Interpretation: 1st Degree AV Block

Deviation from NSR? PR Interval > 0.20 seconds

Rate

Regularity

P waves

PR Interval

QRS Duration

50 bpm

Regularly irregular

normal

lengthens

0.08 seconds

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Interpretation: 2nd Degree Type I AV Block

Deviation from NSR? PR Interval progressively lengthens until dropped beat, pattern resets

Rate

Regularity

P waves

PR Interval

QRS Duration

40 bpm

Regular

Normal

0.14 seconds

0.08 seconds

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Interpretation: 2nd Degree Type II AV Block

Deviation from NSR? PR Interval normal when present; occasionally atrial impulse blocked

Rate

Regularity

P waves

PR Interval

QRS Duration

40 bpm

Regular

No relation to QRS

none

Wide (>0.12 sec )

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Interpretation: 3rd Degree AV Block

Deviation from NSR? Atrial impulses are completely blocked; ventricles working independently.

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Ventricular Cell Problems

Occasional depolarization from 1 or more foci within the ventricles

Premature Ventricular Complex (PVC)

Rapid, regular depolarization from irritable foci within the ventricles

Ventricular Tachycardia

Disorganized quivering of the heart muscle, ineffective cardiac output

Ventricular Fibrillation

Rate

Regularity

P waves

PR Interval

QRS Duration

40 bpm

varies

Upright when present

0.14 seconds

variable

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Interpretation: Sinus with Premature Ventricular Contractions (PVC)

Deviation from NSR? Ectopic beat originating in the ventricles resulting in wide, bizarre QRS

Rate

Regularity

P waves

PR Interval

QRS Duration

160 bpm

regular

none

none

Wide (>0.12 seconds)

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Interpretation: Ventricular Tachycardia

Deviation from NSR? Ventricular cells fire continuously – life threatening dysrhythmia

Rate

Regularity

P waves

PR Interval

QRS Duration

40 bpm

regular

none

none

Wide (>0.12 seconds)

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Interpretation: Idioventricular

Deviation from NSR? Escape rhythm to prevent complete cardiac standstill

Rate

Regularity

P waves

PR Interval

QRS Duration

irregular

disorganized

none

none

none

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Interpretation: Ventricular Fibrillation

Deviation from NSR? Multiple ventricular foci firing without effective contractions – life threatening dysrhythmia

Rate

Regularity

P waves

PR Interval

QRS Duration

none

none

none

none

none

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Interpretation: Asystole

Deviation from NSR? No electrical activity in the heart

Let’s review…

The heart has two functioning systems

The mechanical system = pulse & BP

The electrical system = cardiac monitor

The EKG represents the electrical conduction system and how the various cells are depolarizing and repolarizing

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Let’s review (continued)…

Upright P waves = atrial depolarization

QRS Complexes = ventricular depolarization

Any deviation from “Normal” Sinus Rhythm is a dysrhythmia, not all deviations are lethal.

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Lastly…

Rhythm recognition takes lots of practice, think of it like learning another language.

Remember, what you see on the monitor is only telling a small part of the cardiac story for your patient, you must actually touch and assess them.

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