Cardiac stress test

Diagnostic test used to evaluate heart function under stress

Cardiopulmonary exercise test using a treadmill.

Stress test

Stress-ECG of a patient with coronary heart disease: ST-segment depression (arrow) at 100 watts of exercise. A: at rest, B: at 75 watts, C: at 100 watts, D: at 125 watts.

A cardiac stress test is a diagnostic procedure used to evaluate how well the heart functions under physical or pharmacologic stress. It helps in detecting coronary artery disease (CAD), heart rhythm abnormalities, and exercise tolerance.

The test measures the heart’s response to increased workload by monitoring:

• Heart rate
• Blood pressure
• Electrocardiogram (ECG) changes
• Oxygen consumption

Cardiac stress tests are commonly performed in patients with chest pain, shortness of breath, or a history of heart disease. They are also used to assess the effectiveness of treatments such as coronary stents or bypass surgery.

Types of Cardiac Stress Tests

There are different types of stress tests, categorized based on how stress is induced:

1. Exercise Stress Test

The exercise stress test, also known as the treadmill or bicycle stress test, evaluates how the heart responds to physical exertion. The patient exercises on a treadmill or stationary bicycle while heart function is continuously monitored.

• Procedure:
• Electrodes are attached to the chest, arms, and legs for ECG monitoring.
• A blood pressure cuff measures BP at intervals.
• The patient walks on a treadmill or pedals a bicycle with increasing difficulty.
• The test continues until target heart rate is reached or symptoms like chest pain, fatigue, or abnormal ECG changes occur.

2. Pharmacologic Stress Test

For patients who cannot exercise, a pharmacologic stress test is performed. This involves using medications to mimic exercise by increasing heart workload.

• Common Medications Used:
• Dobutamine – Increases heart rate and contractility.
• Adenosine/Dipyridamole (Persantine) – Causes vasodilation, increasing blood flow.
• Regadenoson (Lexiscan) – A newer agent used for vasodilator stress testing.

3. Nuclear Stress Test

A nuclear stress test (also called a myocardial perfusion imaging test) uses radioactive tracers to visualize blood flow to the heart.

• Procedure:
• A radioactive tracer (such as technetium-99m or thallium-201) is injected into the bloodstream.
• A special gamma camera captures images of the heart at rest and stress conditions.
• Any areas with poor blood flow (ischemia) appear as defects in the images.

This test is highly sensitive for detecting coronary artery disease and assessing heart muscle viability.

4. Stress Echocardiogram

A stress echocardiogram combines an exercise or pharmacologic stress test with an ultrasound of the heart.

• Procedure:
• Baseline echocardiogram (heart ultrasound) is taken at rest.
• The patient undergoes exercise or receives stress-inducing medication.
• Post-exercise echocardiogram images are captured to assess changes in heart function.

This test evaluates heart wall motion abnormalities, which can indicate areas of reduced blood supply.

Indications for a Cardiac Stress Test

Cardiac stress tests are used to assess heart function in various conditions, including:

• Coronary artery disease (CAD) detection – Identifies narrowed or blocked arteries.
• Evaluation of chest pain (angina) – Determines if symptoms are due to ischemia.
• Assessment of heart rhythm abnormalities (arrhythmias) – Detects stress-induced palpitations or irregular beats.
• Monitoring treatment effectiveness – Evaluates the success of angioplasty, stent placement, or bypass surgery.
• Preoperative cardiac risk assessment – Determines heart health before major surgeries.
• Exercise capacity evaluation – Helps assess functional limitations in cardiac patients.

Preparation for the Test

Before undergoing a cardiac stress test, patients are given specific instructions, such as:

• Fasting for 3-4 hours before the test (especially for nuclear stress tests).
• Avoiding caffeine and certain medications that may interfere with results.
• Wearing comfortable clothing and shoes for exercise-based tests.
• Informing the doctor about current medications (e.g., beta-blockers may need to be stopped temporarily).

Interpreting Test Results

The results of a cardiac stress test help in diagnosing heart conditions:

Normal Results

• No ECG changes suggestive of ischemia.
• Normal heart rate and blood pressure response.
• No signs of decreased blood flow on imaging studies.

Abnormal Results

• ST-segment depression or elevation on ECG – Suggests myocardial ischemia.
• Abnormal heart rate or blood pressure response – May indicate autonomic dysfunction or cardiovascular disease.
• Reduced blood flow areas on nuclear imaging – Indicates blockage or previous heart damage.

Risks and Limitations

Cardiac stress tests are generally safe, but potential risks include:

• Dizziness or fainting – Due to low blood pressure.
• Chest pain or palpitations – If the test triggers angina or arrhythmias.
• Allergic reaction – Rare, but possible with contrast agents in nuclear stress tests.
• Heart attack (extremely rare) – Occurs in high-risk individuals with severe CAD.

Alternatives to a Cardiac Stress Test

For patients unable to undergo stress testing, alternative tests include:

• Coronary CT Angiography (CTA) – A non-invasive scan to visualize coronary arteries.
• Cardiac MRI – Provides detailed images of heart structure and function.
• Invasive Coronary Angiography – A catheter-based test for direct visualization of arteries.

Conclusion

A cardiac stress test is a valuable tool for diagnosing coronary artery disease, arrhythmias, and exercise intolerance. The choice of test depends on patient condition, symptoms, and risk factors. Early detection and management of heart disease through stress testing can significantly improve patient outcomes.

See Also

• Coronary artery disease
• Electrocardiogram or ECG
• Myocardial infarction
• Echocardiography
• Nuclear medicine
• Cardiac rehabilitation

External Links

• American Heart Association - Stress Testing
• MedlinePlus - Cardiac Stress Test
• NCBI Bookshelf - Stress Testing

Cardiovascular disease A-Z

Most common cardiac diseases

• Cardiac arrhythmia‎
• Cardiogenetic disorders‎
• Cardiomegaly‎
• Cardiomyopathy‎
• Cardiopulmonary resuscitation‎
• Chronic rheumatic heart diseases‎
• Congenital heart defects‎
• Heart neoplasia‎
• Ischemic heart diseases‎
• Pericardial disorders
• Syndromes affecting the heart‎
• Valvular heart disease‎

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

• Accelerated idioventricular rhythm
• Acute decompensated heart failure
• Arteriosclerotic heart disease
• Athletic heart syndrome
• Atrial flutter
• Atrioventricular fistula
• Cardiovascular disease in Australia
• Autoimmune heart disease

B

• Brown atrophy of the heart

C

• Ebb Cade
• Cardiac allograft vasculopathy
• Cardiac amyloidosis
• Cardiac asthma
• Cardiac tamponade
• Cardiogenic shock
• Cardiogeriatrics
• Cardiorenal syndrome
• Cardiotoxicity
• Carditis
• Coronary artery aneurysm
• Coronary artery anomaly
• Coronary artery disease
• Spontaneous coronary artery dissection
• Coronary artery ectasia
• Coronary occlusion
• Coronary steal
• Coronary thrombosis
• Coronary vasospasm
• Cœur en sabot
• Coxsackievirus-induced cardiomyopathy

D

• Duke Treadmill Score
• Duroziez's disease

E

• Eisenmenger's syndrome
• Embryocardia
• Endocardial fibroelastosis
• Eosinophilic myocarditis

H

• Heart attack
• Heart failure
• Heart failure with preserved ejection fraction
• Heart to Heart (1949 film)
• High-output heart failure
• Hyperdynamic precordium

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

I

• Idiopathic giant-cell myocarditis
• Interventricular dyssynchrony
• Intraventricular dyssynchrony
• Isolated atrial amyloidosis

K

• Keshan disease

L

• Loeffler endocarditis

M

• Mydicar
• Myocardial bridge
• Myocardial disarray
• Myocardial rupture
• Myocardial scarring
• Myocardial stunning
• Myocarditis

N

• Nonbacterial thrombotic endocarditis

O

• OLR1
• Ostial disease

P

• Papillary fibroelastoma
• Pathophysiology of heart failure
• Postpericardiotomy syndrome
• Pulmonary vein stenosis

R

• Right axis deviation
• Roemheld syndrome

S

• Saturated fat and cardiovascular disease
• SCAR-Fc
• Shone's syndrome
• Strain pattern
• Subacute bacterial endocarditis
• Sudden cardiac death of athletes

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

T

• Traumatic cardiac arrest

V

• Ventricular aneurysm
• Vibroacoustic disease
• Viral cardiomyopathy

W

• Waon therapy