7.1: EKG Machine and Supplies

EKG machine

Diagnostic test that measures heart muscle activity by magnifying the sound of the electrical signal and records waves of the amplified sounds onto rhythm strips

How would you quickly describe an EKG test to a patient?

It is a non-invasive and painless test that records the electrical activity of the heart in just a few minutes

The EKG machine monitors ______ _____ and ________

Heart rate and arrhythmia

An EKG test can evaluate the effects of ________ or ________ __ ___ _______

Disease or injury of the heart

An EKG test can evaluate the function of an ________ _________

Implanted pacemaker

An EKG test can evaluate the heart’s response __ __________

To medication

The EKG machine is used to obtain a baseline recording ______, _______, ___ ______ to _____ _________

Before, during, and after surgical procedures to verify heart stability

An EKG test can evaluate for ______ __ ____________ __________

Signs of myocardial infarction

An EKG test can assess the effects of medications and __________ on the heart

Electrolytes

An EKG test can identify the presence of _________ _____________

Ischemic changes

Myocardial ischemia

The lack of oxygenated blood flow to the heart muscle, causing tissue death and chest pain

An EKG test can detect the ____________ __ ____ ______ of the heart

Enlargement of one side

The EKG machine can record _____ ________ ________ __________

Blood pressure without analyzing

Differential diagnosis

Tests or procedures performed to find potential causes for conditions with similar symptoms

Blood pressure, cardiac output (CO), and pulse

Used to assess the mechanical condition of the heart, NOT an EKG test

Cardiac output (CO)

Determined by pulmonary circulation and is measured by the volume of blood that is pumped within 1 minute by the right or left ventricle; an EKG test CANNOT determine this

Cardiac muscle hypertrophy

Abnormal thickening of the heart muscle that CANNOT be detected by an EKG test

Acquisition module

The electrical signals coming from the patient’s skin travel through the lead wires are received by this component and converted into readable data on graph paper

Lead wires

Measure the fluctuation of voltage differences between positive and negative circuits, which travel from the electrodes placed on the skin to the acquisition module

Adapter clips

Connects the electrodes on the patient’s skin to each lead wire

Electrode

A self-adhesive pad containing a conductive gel that amplifies the electrical current traveling from the patient’s skin, through the attached lead wire, and to the EKG machine

Standard 12-lead EKG

Most common type of EKG consisting of only 10 leads

Ground lead

The limb lead attached to the RF that acts as a safety wire which reduces electrical interference from outside the body, but does NOT carry any current

Bipolar leads

• Electrical voltage has 2 poles

• Electrical current flows from the negative pole to the positive pole

• Produces a view originating from the heart

Unipolar leads

Records electrical voltage in only one direction (from only one pole)

Standard limb leads

Bipolar leads that record voltage differences between the wrists and legs, in which the electrical current flows from the limbs toward the heart

RA

Lead placed on the right wrist

LA

Lead placed on the left wrist

LL

Lead placed on the left ankle

Einthoven’s triangle

Each electrode is paired such that the electrical current flows from one negative pole towards the positive pole, showing a potential difference between each bipolar standard limb lead

Each view produced in the Einthoven’s triangle is _______ ____ ___ _________

Always from the positive electrode

Each electrical current in the Einthoven’s triangle moves from _________ _____ __ _________ _____

Negative pole to positive pole

Coronal plane

An imaginary plane that divides the heart into anterior and posterior portions

Lead I

The RA carries a negative charge towards the positive pole of the LA in Einthoven’s triangle

High lateral wall of the left ventricle and left atrium

View produced by Lead I in Einthoven’s triangle

Lead I diagram

Lead II

The RA carries a negative charge downwards 60° to the positive pole of the LL in Einthoven’s triangle

Inferior wall of the left ventricle, right ventricle, and apex of the heart

View produced by Lead II in Einthoven’s triangle

Lead II diagram

Lead III

The LA carries a negative charge 120° downward to the positive pole of the LL

The inferior wall of both the left and right ventricles

View produced by Lead III in Einthoven’s triangle

Lead III diagram

Augmented leads

• Unipolar leads that provide 3 frontal plane views from the central point of the heart

• Only produces 2 views of the heart wall from the left arm and the left foot

Augmented leads triangle

Forms a triangle in which each electrical flow of a unipolar lead travels outwards from the center of the heart, toward a single positive electrode on a limb

How do the augmented leads affect the electrical signals from the heart?

Amplify the signal by 50% more that other leads, making it possible to view the waveforms printed on graph paper

What provides the negative pole in the aV lead triangle?

A combination of 2 limb electrodes, which is referenced against a single positive electrode

Lead aVR

Unipolar augmented lead that does not provide a view of the heart, so it is rarely used

Lead aVL

Unipolar augmented lead where the positive electrode is placed on the LA to provide a view of the lateral wall of the heart

Lead aVF

Unipolar augmented lead that provides a view of the interior wall of the left ventricle

Small box on EKG paper

Large box on EKG paper

Bedside monitor

EKG machine that can be found in an ICU and in a hospital’s emergency department

Portable EKG machine

A handheld device that is typically used in isolated wards, ambulances, and remote monitoring units to perform EKGs quickly and easily

Why are portable EKG machines preferred over bedside monitors?

Easier to use and can connect via USB port or Bluetooth

What should you do if there are no available pediatric electrodes?

Cut each adult electrode in half before sticking

Stress test

Monitors cardiac changes as a patient runs on a treadmill or receives medication that mimics the effects of doing so

What prevents a patient from running on a treadmill for a stress test?

Injuries, age, weight, or severity of illness

Holter monitor

Continuously monitors heart electrical activity for a 24 to 48 hour time period as the patient carries out typical daily activities

What kind of heart conditions does a Holter monitor measure?

Arrhythmias, heart irregularities, and chest pain or tightness

Patient responsibilities while wearing a Holter monitor

Record any symptoms in a diary and press the “event” button whenever they feel signs beginning

How many leads does a Holter monitor use?

5 to 7 leads

Event monitor

Continuously monitors heart electrical activity for up to 30 days

What are the only instances in which a patient is allowed to remove the event monitor?

When the battery must be recharged or if the patches need to be replaced

How does the patient record symptoms while wearing an event monitor?

By using a designated cell phone

Why is a magnet sometimes used on patients with an implanted pacemaker?

It temporarily stops its function, which provides a non-pacemaker reading