EKG

Objective:

• The student will become familiar with an EKG and how it works to record the electrical activity of the heart

• The student will become familiar with how to read an EKG and what the significance of the EKG is

Question of the day:

• What do all of those lines mean anyway?

What is an EKG?

– An EKG also known as an electrocardiogram, is used for recording the electrical activity of the heart.

How is an EKG performed?

• This test is performed by placing electrodes on the arms, legs, and chest.

• The electrodes monitor the electrical activty of the heart and records it onto EKG graph paper where one large block equals .20 seconds (each small block is .04 seconds and 5 small blocks make up one large block)

• There are 4 lead EKGs and 12 lead EKGs

4 lead EKG vs. 12 lead EKG

• Electrode placement

http://www.biolog3000.com/electrodepl.jpg

Reading a 12 lead EKG

http://www.ems1.com/data/images/EKG_Case4_Large1.jpg

Just in case you were wondering ..

• Einthenoven was the first person to label the different waves (P, Q, R, S, T) that the ECG showed, and was also the first person to actually describe what each wave sequence of a certain heart disorder looked like.

Early ECG Machines

EKG:

http://www.msjc.edu/pic/224/ekg.gif

What do all those lines mean?• The P wave and QRS complex both demonstrate

depolarization. – Depolarization initiates contraction of resting myocytes as the

charge within each cell changes to positive

• The P wave represents atrial depolarization• The QRS complex represents ventricular depolarization.• The T wave demonstrates recovery or repolarization of

the myocytes

Please note:

• These “waves” are NOT heart muscle contractions!

• They are the electrical events that precede muscle contraction/heart beat!!

Sinus Rhythm:

• “Normal” Heart Rhythm between 60-100 bpm with a slight irregularity of rhythm due to normal breathing

Bradycardia:• Described as a resting heart rate less than 60

bpm• Usually not problematic unless HR falls below 50

bpm• Common “condition among endurance athletes

Tachycardia• Cardiac Arrhythmia that refers to a rapid beating

of the heart usually over 100 bpm• This can be considered normal if it is as a result

of exercise or stress

Complications of Tachycardia:• if the heart is pumping too rapidly for an

extended period of time it will change the balance of oxygen and carbon dioxide in the blood

• When the heart beats too rapidly, it may pump blood less efficiently by not allowing the atria and ventricles to fill completely before contracting

• Also, the faster the heart beats, the more oxygen and nutrients the heart requires which takes those much needed nutrients away from other parts of the body

Atrial Fibrillation

• Irregularly irregular arrhythmia • In atrial fibrillation, the electrical impulses that

are normally generated by the SA node are replaced by disorganized activity in the atria resulting in irregular conduction of impulses to the ventricles that generate the heartbeat

Ventricular Tachycardia (V-tach): Tachycardia that begins in the ventricles, may lead to ventricular

fibrillation.

Uncoordinated contraction of the cardiac muscle of the ventricles of the heart, making them tremble rather than contract properly

Myocardial Infarction:• More commonly known as a heart attack occurs

when blood supply to the heart is interrupted and results in an ischemic injury

Asystole:• You tell me …..

EKG game

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