[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Clinical exam](https://durgical.com/en/clinical-exam/) › [Cardiovascular system](https://durgical.com/en/clinical-exam/areas/cardiovascular/) › Cardiac studies: stress test, Holter, echo, nuclear, EP study and cath

# Cardiac studies: stress test, Holter, echo, nuclear, EP study and cath

- Topic

The main heart tests after the ECG: what each one shows, when it is chosen, how the patient is prepared and what can go wrong.

Updated Nov 13, 2026

## Key points

- Ischemia tests: exercise ECG first if the patient can walk and the ECG is readable; otherwise nuclear or stress echo.
- Holter for frequent symptoms (daily); event or loop recorder for rare ones.
- Echocardiography is the first imaging test for murmurs, heart failure and suspected hypertrophy.
- TEE sees the back of the heart better: left atrial appendage clot, endocarditis, prosthetic valves.
- After cardiac catheterization: puncture site, distal pulses and kidney function are the nurse's three checks.

## What it is

After the history, examination and resting ECG, a few studies answer most cardiac questions. Exercise testing and nuclear perfusion imaging look for ischemia; Holter and event monitors catch intermittent arrhythmias; echocardiography with Doppler shows chambers, walls, valves and pressures; the electrophysiology study maps the conduction system; cardiac catheterization measures pressures and shows the coronary arteries. They go from non-invasive and risk-free to invasive, and the choice depends on the clinical question and the patient's risk.

## Key facts

- A positive exercise test classically shows horizontal or downsloping ST depression of 1 mm or more, or angina, or a fall in blood pressure with effort.
- Pharmacological stress uses a vasodilator or dobutamine when the patient cannot exercise.
- Doppler measures blood velocity, which lets the echo estimate valve gradients and pulmonary artery pressure without a catheter.
- An ejection fraction below about 40% on echo defines heart failure with reduced ejection fraction.
- A reversible perfusion defect means ischemia; a fixed defect usually means scar.
- Catheterization is the reference for coronary anatomy and allows treatment (angioplasty, stent) in the same session.

## Step by step

- Before any study, confirm identity, the indication and that the patient understands the test; obtain written consent for invasive ones.
- Check fasting, allergies (contrast, iodine, latex, tape), pregnancy, kidney function and anticoagulants for invasive or contrast studies.
- Remove metal, place electrodes on clean dry skin and record baseline vital signs and ECG.
- During the test, watch symptoms, rhythm and blood pressure; stop and call for help if chest pain, severe dyspnea or arrhythmia appear.
- After catheterization or an EP study: check the puncture site, distal pulses, colour and temperature of the limb, and vital signs at set times.
- Encourage fluids after contrast when allowed, and record urine output.
- Teach warning signs at home: bleeding or swelling at the puncture, chest pain, fainting.

## Cardiac studies from least to most invasive.

| Study | What it shows | Chosen when | Preparation and nursing | Main risks and limits |
| --- | --- | --- | --- | --- |
| [Exercise ECG (treadmill or bicycle)](https://durgical.com/en/conditions/stable-angina/) | ST changes, symptoms, blood pressure response, arrhythmias and exercise capacity under rising workload | Suspected stable angina with an interpretable resting ECG who can exercise; prognosis after infarction; exercise-related arrhythmia | Several hours without food, smoking or caffeine; comfortable shoes; the team asks which medicines to hold; resuscitation equipment at hand | Rare infarction or arrhythmia; not done in unstable angina or severe symptomatic aortic stenosis; less accurate with LBBB, paced rhythm or digoxin |
| [Holter and event monitors](https://durgical.com/en/conditions/syncope/) | Continuous rhythm for 24–48 hours (Holter) or longer (event or loop recorders), matched to a symptom diary | Palpitations, syncope or dizziness of possible rhythm origin; checking rate control or a new drug | Shower before; skin prepared for electrodes; teach the diary; avoid water and strong magnetic fields | Painless; electrode skin reaction; misses symptoms that do not occur while it is worn |
| [Echocardiography (transthoracic, transesophageal) with Doppler](https://durgical.com/en/conditions/heart-failure/) | Chamber size, wall thickness and motion, ejection fraction, valves, pericardial fluid, estimated pressures and blood flow direction | Murmur, heart failure, suspected endocarditis, tamponade, cardioembolic stroke, hypertrophy seen on ECG | TTE: none. TEE: fasting, sedation, throat anaesthesia, nothing by mouth until swallowing returns | TTE: no known risk, limited by obesity or lung disease. TEE: sedation reactions, rare esophageal injury |
| [Nuclear perfusion imaging (SPECT, PET)](https://durgical.com/en/conditions/stable-angina/) | Tracer uptake in the myocardium at rest and under exercise or drug stress: fixed defects (scar) versus reversible defects (ischemia) | Patients who cannot exercise or whose ECG cannot be read; locating ischemia; viability | Fasting and no caffeine for about a day (caffeine blocks vasodilator stress); intravenous line; ask about asthma | Small radiation dose; bronchospasm or blocks with vasodilators; attenuation artefacts |
| [Electrophysiology study](https://durgical.com/en/conditions/wolff-parkinson-white-syndrome/) | Intracardiac signals and conduction times; induction and mapping of arrhythmias | Unexplained syncope with heart disease, WPW, recurrent tachycardias before ablation, sudden-death risk | Fasting, consent, intravenous line, sedation; monitor rhythm and puncture sites afterwards | Bleeding, thrombosis, induced arrhythmias, rarely tamponade or stroke |
| [Cardiac catheterization and coronary angiography](https://durgical.com/en/conditions/myocardial-infarction/) | Intracardiac pressures and oxygen saturations, cardiac output, coronary anatomy with contrast; ventriculography; biopsy | Acute coronary syndrome, positive non-invasive tests, valve or congenital disease before surgery, pulmonary hypertension | Fasting, consent, allergies and kidney function checked; after: puncture site, distal pulses, limb position, bleeding, urine output | Bleeding and hematoma, arterial injury, arrhythmia, infarction, stroke, contrast allergy and contrast kidney injury |

## Test yourself

Think of the answer, then tap the question to see it.

## Which ECG change during exercise testing classically suggests ischemia?

Horizontal or downsloping ST depression of 1 mm or more, especially with angina or a fall in blood pressure.

## Why must a patient avoid caffeine before a vasodilator nuclear stress test?

Caffeine blocks the adenosine receptors that the vasodilator acts on, so the stress and the images become unreliable.

## When is a transesophageal echo preferred to a transthoracic one?

When images are poor or the back of the heart matters: left atrial appendage clot, endocarditis, prosthetic valves or the aorta.

## What does the nurse check after a femoral or radial cardiac catheterization?

The puncture site for bleeding or hematoma, distal pulses, colour and temperature of the limb, vital signs and urine output after contrast.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/clinical-exam/cardiac-studies-stress-test-holter-echo-nuclear-ep-study-and-cath/)

## Elsewhere in DurgiPedia

- [ECG basics: waves, intervals and leads](https://durgical.com/en/physiology/ecg-basics-waves-intervals-and-leads/)
- [Iodinated contrast: reactions and the kidney](https://durgical.com/en/radiology/iodinated-contrast-reactions-and-the-kidney/)
- [Radiation in medical imaging: risk, ALARA and pregnancy](https://durgical.com/en/radiology/radiation-in-medical-imaging-risk-alara-and-pregnancy/)

## Connections

## Related 5

- [The abnormal ECG: hypertrophy, conduction blocks and main arrhythmias](https://durgical.com/en/clinical-exam/the-abnormal-ecg-hypertrophy-conduction-blocks-and-main-arrhythmias/)
- [Chest pain: ischemic, pericardial, pleural and other patterns](https://durgical.com/en/clinical-exam/chest-pain-ischemic-pericardial-pleural-and-other-patterns/)
- [Murmurs: timing, grade, location and radiation](https://durgical.com/en/clinical-exam/murmurs-timing-grade-location-and-radiation/)
- [Heart failure syndrome: left- and right-sided signs](https://durgical.com/en/clinical-exam/heart-failure-syndrome-left-and-right-sided-signs/)
- [Peripheral pulses and the ankle–brachial index](https://durgical.com/en/clinical-exam/peripheral-pulses-and-the-ankle-brachial-index/)

## Related conditions 7

- [Stable angina](https://durgical.com/en/conditions/stable-angina/)
- [Myocardial Infarction (Heart Attack)](https://durgical.com/en/conditions/myocardial-infarction/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Aortic Valve Stenosis](https://durgical.com/en/conditions/aortic-valve-stenosis/)
- [Syncope (vasovagal, orthostatic hypotension, cardiac)](https://durgical.com/en/conditions/syncope/)
- [Wolff-Parkinson-White syndrome](https://durgical.com/en/conditions/wolff-parkinson-white-syndrome/)
- [Hypertrophic cardiomyopathy](https://durgical.com/en/conditions/hypertrophic-cardiomyopathy/)

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Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: [Exercise stress test: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003878.htm) (MedlinePlus, U.S. National Library of Medicine, 2026); [Echocardiogram: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003869.htm) (MedlinePlus, U.S. National Library of Medicine, 2026); [Nuclear stress test](https://medlineplus.gov/ency/article/007201.htm) (MedlinePlus, U.S. National Library of Medicine, 2026); [Cardiac catheterization: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003419.htm) (MedlinePlus, U.S. National Library of Medicine, 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/clinical-exam/cardiac-studies-stress-test-holter-echo-nuclear-ep-study-and-cath/