Basic Dysrhythmia Interpretation

Basic Dysrhythmia Interpretation

Part I of II

Objectives

• Anatomy and Physiology of the Heart
• What is an EKG?
• Stages of the cardiac cycle
• How to measure
• Steps to Interpret Rhythms

Four Chambers of the Heart

Heart Sounds

"Lub"

"Dub"

Closure of atrio-ventricular valves

Closure of semi-lunar valves (after ventricular contraction).

WHAT MAKES THE HEART PUMP?

Natural electrical activity

When the muscle contracts, it squeezes the blood through the heart and to the lungs or to the body

Electrical impulses stimulate heart muscle to contract

The heart is made primarily of muscle

WHERE DOES THE ELECTRICITY COME FROM?

PACEMAKERS

SA Node

The primary pacemaker is the SA NODE located at the top of the right atrium

The heart has natural power generators that tell the heart to pump

AV Node

Secondary pacemakers are scattered throughout the heart and function as lifesaving backup if the SA node fails. Although sometimes they malfunction.

The AV node is located in the junction of both atria and ventricles

Electrical Conduction Pathway

"Power lines" quickly carry electrical impulses from the pacemakers throughout the heart

If the SA node fails, the heart will use a different "power source" to stimulate contraction. As the heart uses lower foci for energy, the intrinsic rate is also lower. The ventricular foci only has a rate of 20-40 bpm. For most people, this is not high enough to oerfuse all of the organs efficiently.

Each area can pace, but not as well as the area before it.

DECODING A RHYTHM STRIP

The electrical basis of an EKG

Electrodes sense the cardiac activity and give us a picture of how they are traveling in the form of an

ELECTROCARDIOGRAM

This is printed on EKG paper and is called a Rhythm strip or an EKG strip

EKG Leads

Electrode

An adhesive pad that contain conductive gel and attaches to the patients skin

Lead

The lead wires connect the electrodes to the cardiac monitor.

These lines represent the electricity traveling over specific parts of the heart

Stages of the heartbeat

P wave, QRS & T wave make up one complete CARDIAC CYCLE

TO KNOW IF THE HEART IS HEALTHY, WE MEASURE THE SIZE OF THESE WAVES

Measurement Guide

How to use EKG paper to measure

• Heart Rate
• P- Wave
• PR- Interval
• QRS-Interval
• QT-complex (advanced)

What do we measure?

Calculating Heart Rate

Method #1

Divide 300 by the number of large squares between the R-R interval.

*Only use these methods with a regular rhythm

Method #2

Count the number of beats by 10. (Must be a 6 second strip.

P-Wave

Characteristic of a NORMAL P wave

• Smooth, Upright, Rounded
• Positive in Lead II
• 0.5 to 2.5 mm in height 0
• 0.10 seconds in or less in duration
• One sinus P wave to each QRS complex

PR-Interval

The normal PR interval measures 0.12-0.20 seconds (120-200 milliseconds)

The PR-interval starts at the beginning of the P wave (atrial depolarization) and ends at the beginning of the QRS complex (ventricular depolarization).

• Represents ventricular depolarization
• The normal duration (interval) of the QRS complex is between 0.08 and 0.10 seconds (80- 100 miliseconds).

• When the duration is between 0.10 and 0.12 seconds, it is intermediate or slightly prolonged.

• A QRS duration of greater than 0.12 seconds is considered abnormal.

QRS-Interval

ST segment

• Represents early ventricular repolarization.

• Should be a flat line between QRS complex and T wave
• Deviation from baseline is abnormal. Above: ST Elevation Below:ST depression

T-wave

Normally rounded and slightly asymmetrical

• Represents ventricular repolarization
• Begins as the deflection gradually slopes upward from ST segment
• Ends when the waveform returns to baseline

Coming Soon..."Steps to interpret cardiac rhythms"

QT-interval

• Represents the entire duration of ventricular depolarization and repolarization
• Measured from the beginning of the QRS complex to the end of the T wave
• Varies with heart rate, so must be corrected (QTc). (Generally, the QT interval should not be more than half of the R - R interval)
• The longer the QT interval the higher the patients risk of v-fib

Threats

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• Establish a flow through the content.
• Measure results.

Weaknesses

Contextualize your topic

• Plan the structure of your communication.
• Give it a hierarchy and give visual weight to the main point.
• Add secondary messages with interactivity.
• Establish a flow through the content.
• Measure results.

Strengths

Contextualize your topic

• Plan the structure of your communication.
• Give it a hierarchy and give visual weight to the main point.
• Add secondary messages with interactivity.
• Establish a flow through the content.
• Measure results.