Chapter 12: Cardiac Stress Testing

Why may a doctor order an exercise stress test for a patient?

Their ECGs may appear normal

Exercise electrocardiography

Non-invasive type of cardiac stress testing that uses an exercise treadmill while their ECG is continuously monitored. The level of exercise is increased as the test goes on.

Other names for electrocardiography

1. Exercise tolerance test

2. Treadmill stress test

3. Stress ECG

4. Exercise treadmill test

What does common exercise electrocardiography equipment include?

A treadmill, an ECG machine, and a monitor

Noninvasive

Procedure that does not require entrance into a body cavity, tissue, or blood vessel

Who monitors the patient during the stress test?

Cardiologist and in same cases advanced cardiac life support certified professionals

What happens during the test?

Patient is asked to walk on a treadmills. The level of exertion is increased as the test progresses. 

What other things are monitored during a stress test beside the ECG?

blood pressure, heart rate, oxygen saturation, and physical appearance

Toward the end of each exercise stage, what is obtained?

Blood pressure and a 12-lead ECG

What is the patient asked to report during the test?

any chest pain, dizziness, shortness of breath or other symptoms

What is the goal of a treadmill test?

To exercise the heart and evaluate how it responds to the stress of exercise

What is your role as a healthcare professional?

To provide patient instruction and monitor patient during the procedure by taking blood pressure and other measurements. You also observe patient and apply/remove electrodes.

What are some basic responsibilities during an electrocardiograph

1. Always know location of crash cart and AED

Make sure you always report abnormalities such as ______ or ______ to the physician.

Tachycardia; tachypnea

Why is exercise electrocardiography considered non invasive?

It does not require an entrance into a body cavity, tissue, or blood vessel

Name at least three responsibilities you will have during electrocardiography

1. Provide for safety and prepare for emergencies

2. Explain, obtain, and prepare patient prior to procedure

3. Monitor the patient including blood pressure and 12-lead ECG

Exercise electrocardiography is used to evaluate how the heart and blood vessels respond to and it is used for what conditons?

physical activity

When is treadmill stress testing typically pefromed?

When a physician suspects a cardiac problem, most commonly coronary artery disease

Coronary artery disease

due to atherosclerosis which occurs when plaque forms in blood vessels from an accumulation of excess fat

If a patient has CAD, what happens to blood flow?

It will not increase in response to exercise because the arteries are narrowed or obstructed

What is a ST depression?

An abnormally low ST segment below the normal baseline of the ECG. It may indicate myocardial ischemia, which can occur during exercise electrocardiography. 

How does CAD affect the ECG tracing

ST depression which may indicate myocardial ischemia or infarction and should be reported to the doctor

What are other causes of ST depression?

Certain medications, hypothermia, hypokalemia

What is angina?

An oppressive pain or pressure that occurs when heart muscle does not receive enough oxygen due to partial or complete blockage of coronary artery. Symptoms include: weakness, shortness of breath, palpitations and dizziness.

Chemical stress test

Stress test performed after administering medications that cause the heart rate to increase or the coronary blood vessels to dilate; performed on patients who cannot perform the exercise required in a regular stress test

When is a chemical stress test used?

When the patient is unable to run or walk on a treadmill or use an exercise bike due to age, injury, or physical defect

T/F: Chemical stress tests can conducted using nuclear testing or in combination with echocardiography.

True

How is a chemical stress test conducted?

Requires one or more IVs for the introduction of a stressing chemical such as Adenocard, Persantine, dobutamine

Nuclear Stress Test

A stress test in which radionuclides are administered to trace the path of blood through the heart

Nuclear Stress Test Process

Nuclear medicine technologist inject patient with a stressing chemical. Then prior to the end of the stressing cycle, the tech injects a radioactive tracer. Then patient is scanned with a gamma camera. 

Gamma Camera

Camera that records the gamma radiation emitted by radioactive tracers in patient’s blood. 

How are the patients positioned for a nuclear stress test?

Lying on their back or sometimes sitting upright with arms above their head

What is an additional feature of nuclear testing?

3 lead ECG

Gate

a selective technique in which a gamma camera is triggered by specific events captured by a three lead ECG monitor

What kind of factors can affect nuclear stress test?

• Diet

• Female breast

Echocardiogram

Noninvasive diagnostic test that uses sound to study the heart, heart valves, and blood vessels.

Stress echocardiogram

A test that combines an exercise stress test with an electrocardiogram to assess left ventricular wall motion before and immediately after exercise.

When is a stress echo considered normal?

If the LV wall motion is normal at rest and within 45-60 seconds of achieving the target heart rate poststress.

When is ischemia suspected?

when a change is seen in the LV wall shape or contractility with exercise

How does echo work?

It directs beams of US waves through the chest wall, which are echoed by the heart tissues providing motion pictures of the heart

What are the phases of a stress electrocardiogram?

Resting echo phase, immediate post exercise scan, and recovery phase scan

What kind of images does the sonographer obtain during the resting phase?

Four specific LV wall motion images with patient lying on their left side with head slightly elevated

When is the treadmill stopped for stress echo?

When the pt achieves 85-100% of target heart rate during exercise portion.

Chemical stress echocardiogram

A stress echocardiogram is when the heart is stressed by chemicals instead of physical exercise

When the patient’s heart returns close to _____ _____ ____, the same four LV wall motion images are acquired to complete the _____ ______.

resting heart rate; recovery

What does the cardiologist do with the US scans?

assess for changes in LV motion and contractility, which can predict the presence of ischemia in one or more coronary arteries

Why is communication with the patient important?

It is our responsibility to ensure that the patient understand what will occur during the test and what the patient should report while test is in progress.

Why would it be necessary to use chemical stress testing?

Maybe the patient cannot exercise or has a limb missing

How should the patient prepare for the test?

• Avoid consuming alcohol or caffeine for 24 hours prior to test

• No tobacco

• Not eat or drink anything 4 hrs prior to test

• War comfy shoes and clothing

Informed consent

Affirms that the patient understands treatment, why it is being performed, etc.

What should you do if a pt does not understand why consent form is necessary?

Explain the legal requirements for informed consent and refer to physician if necessary

Pt does not understand procedure you could…

notify the licensed practioner and provide a brochure for patient to review

Patient is illiterate and unable to sign their name

Have a witness present and have the consent form marked with an X by patient and signed by witness and yourself

Patient is unable to sign because glasses are not available or because patient is blind

Make every attempt to obtain glasses and have patient sign to best of their ability

Which type of medications are usually stopped before a stress test?

Beta blockers

What are beta blockers?

Drugs used to treat hypertension

T/F: You may need to complete a pt hx

True

What type of info do you need from a patient for a pt history

Medical history, medications currently being taken, cardiovascular risk factors, and reason. Consent forms must be signed and witnessed.

T/F: You can tell the patient that exercise electrocardiography is about an hour.

False: patient should be informed this is not a TIMED test. Test may take from 45 minutes to 3 hours.

Stress testing is a noninvasive procedure…why is informed consent necessary?

Patients need to affirm they understand the procedure and risks.

Why should you obtain a list of the current medications the patient is taking before the stress test procedure?

Because certain medications should not be taken prior to the test

What do you need to prepare in advance for exercise electrocardiography?

• BP equipment

• Skin prep solution

• Clippers

• Gauze

• Chest electrodes

• Stress test unit

• lead wires

• Treadmill

• adhesive tape

• belt

  • crash cart

When patient arrives what should you do?

1. Make sure they followed guidelines for food, caffeine, etc

2. Observe if pt is dressed appropriately

3. Inquire if certain rx stopped

4. Complete pt hx

5. make sure consent form is signed and

Which is preferred clipping hair or shaving?

Clipping because shaving can leave skin brisk

Attach blood pressure cuff and then

place the precordial electrodes

Where are precordial electrodes placed for an exercise ecg?

Same as a 12-lead

How are the limb leads different than a 12-lead ECG?

Limb sensors must be moved from arms and legs to upper chest and torso

To avoid artifacts, avoid placement electrodes near

patients belt

Mason-Likar Placement

Placement of electrodes for exercise cardiography

Any symptoms the patient complains of should be reported

to the physican

What equipment must be assembled before exercise electrocardiography can be performed?

• bp equipment

• chest electrodes

• stress test unit

• lead wires

• treadmill

Stress test is divided into 

2 or 3 minutes each

Each stage of the stress test is based on

protocols

What do the protocols include?

Length of time of exercise and incline

Bruce Protocol

ECG recordings are made continuously during and after exercise

Modified Bruce Protocol

for patients with limitations due to age or hx of cardiac disease

Naughton protocol

for really sick patients

How can you reduce pt fears?

• Maintaining confidence

• Answering questions

• Following safety precautions

The entire exercise period lasts up to

15 minutes but may vary

What happens at the end of each exercise?

Blood pressure is taken and level of exercise is increased

When does exercise stop?

Why patient reaches symptoms, fatigue or physician notices an issue

Target heart rate

measurement needed to truly exercise the heart

How do you calculate target heart rate?

220-pt age x by a percent

Submaximal 

Target heart of 220 minus the age multiplied by a percentage between 60 and 85. THR = [(220 − age) × 0.60] to THR = [(220 − age) × 0.85]

Maximal

Target heart rate of 220 minus the age of the patient.

Rate pressure product

Systolic blood pressure multiplied by the heart rate; also known as double product.

What are the two main factors determining the workload of the heart?

Systolic blood pressure and heart rate

A person with good blood supply and a strong heart should have a

lower RPPA

person who has a disruption of blood supply to the heart and a weaker heart muscle

higher RPP

A patient who recently has a heart attack

Noughton protocol

A 46 year old pt during a yearly physical

Bruce protocol

Patient with hypertension and chest pain

Modified bruce protocol

The period from when the patient ends their exercise but is still monitored is called the

cooling off period and lasts from 6-15 minutes

What is the goal of the cooling off period?

For the patients BP and heart rate to return to the pretest numbers

What factors are used to interpret the results of exercise electrocardiography?

• Presence of ECG changes and symptoms

• Heart rate and rhythm

• Blood pressure

• Changes in oxygen saturation 

What is an inconclusive test?

A test with questionable results but does not mean necessarily there is an abnormality or potential of an abnormaility

What should the patient do after testing?

• rest for several hours

• Avoid extreme temperatures

• Avoid stimulants

Stress testing is considered a good method to detect

early coronary vascular disease

What percentage of adults have false positive results?

5-15%

False Positive

When a diagnostic test indicates that disease is present but, in reality, no disease is present. A false positive is never considered a negative result. It is a positive result, albeit a falsely positive one.