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.
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) | 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 | 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 | 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) | 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 | 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 | 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.
Elsewhere in DurgiPedia
- ECG basics: waves, intervals and leads
- Iodinated contrast: reactions and the kidney
- Radiation in medical imaging: risk, ALARA and pregnancy
Connections
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 (MedlinePlus, U.S. National Library of Medicine, 2026); Echocardiogram: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Nuclear stress test (MedlinePlus, U.S. National Library of Medicine, 2026); Cardiac catheterization: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026).
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