Cardiac Stress Imaging
Stress Echocardiography
Ultrasound imaging of the heart at rest and under stress — a highly accurate method for detecting coronary artery narrowing and guiding decisions about intervention. More sensitive than a standard treadmill ECG test.
S
The Test
What Is Stress Echocardiography?
Stress echocardiography combines the anatomical and functional information of echocardiography (cardiac ultrasound) with the provocation of stress — either exercise or medication — to assess how the heart copes when its demand for blood increases. At rest, even significantly narrowed coronary arteries may supply adequate blood flow. Under stress, the restricted supply becomes insufficient, causing the affected segment of heart muscle to contract abnormally — a finding called a wall motion abnormality.
Images are acquired at rest and at peak stress simultaneously on a split screen, allowing direct comparison of wall motion in every segment of the heart. This makes stress echocardiography considerably more sensitive and specific for ischaemia than a standard treadmill ECG test: sensitivity for obstructive coronary disease is approximately 80–85%, compared with 68% for exercise ECG alone.
The investigation is safe, free of ionising radiation, and provides both diagnostic and prognostic information in a single appointment. A normal stress echocardiogram is associated with an excellent prognosis — a cardiac event rate of less than 1% per year — and can provide important reassurance to patients with equivocal or ambiguous symptoms.
Two Approaches to Stress
Exercise or Dobutamine — Which Is Used?
The method of stress is selected based on your individual circumstances — primarily whether you are able to exercise adequately. Dr Nijjer will discuss which approach is most appropriate at your consultation.
Preferred when possible
Exercise Stress Echo
Treadmill or semi-supine bicycle ergometer
You exercise on a treadmill or bicycle while echocardiography images are acquired at each stage of exertion. Images at peak exercise are compared directly with rest images, capturing the heart at its most physiologically challenged point. Exercise stress is considered the preferred modality when achievable, as it also provides functional capacity (MET) and heart rate/BP response data.
The echocardiographer acquires images within seconds of peak exercise to capture the findings before the heart rate recovers. A semi-supine bicycle protocol, where you cycle while the probe remains in contact, allows continuous imaging throughout stress.
- Most physiologically natural form of stress
- Provides functional capacity and chronotropic data
- No drug side-effects
- Blood pressure and heart rate response also assessed
For those unable to exercise
Dobutamine Stress Echo
Pharmacological stress via intravenous infusion (DSE)
Dobutamine is a synthetic adrenaline-like drug that mimics the effect of exercise by increasing heart rate and contractility. It is given through a small cannula in the vein, with the dose increased in stages every three minutes until target heart rate is reached. Images are acquired at each stage. The drug clears from the body rapidly — any discomfort resolves within minutes of stopping the infusion.
Dobutamine DSE is the method of choice for patients with joint problems, peripheral vascular disease, neurological conditions, or severe deconditioning that prevents adequate exercise. Atropine may be added to achieve target heart rate if needed.
- Does not require physical fitness or exercise ability
- Continuous imaging throughout the stress protocol
- Drug effects rapidly reversible on stopping infusion
- Validated for viability assessment (low-dose protocol)
Clinical Uses
Who Should Have a Stress Echo?
Suspected Angina
For patients with chest pain or breathlessness on exertion in whom coronary artery disease is suspected, stress echocardiography can determine whether ischaemia is the cause — and, if so, which coronary territory is affected.
Equivocal Exercise ECG
When an exercise stress ECG produces borderline or uninterpretable ST changes (LBBB, LVH, pacemaker rhythm), stress echo provides the definitive anatomical answer the ECG cannot offer.
Known Coronary Disease
After coronary stenting or bypass surgery, stress echo confirms whether revascularisation has been successful and identifies any remaining ischaemia in territories not yet treated.
Pre-Operative Risk Assessment
Before major non-cardiac surgery in patients with elevated cardiac risk, stress echocardiography stratifies perioperative risk and informs the anaesthetic and surgical team.
Myocardial Viability
A low-dose dobutamine protocol (without atropine) identifies hibernating myocardium — heart muscle that is dysfunctional at rest but still viable and capable of recovery after revascularisation. This guides decisions about whether bypass surgery or angioplasty is likely to improve function.
Valve Stress Assessment
In patients with moderate aortic or mitral valve disease and symptoms disproportionate to the resting severity, exercise echocardiography can reveal haemodynamically significant disease provoked by exertion — helping time the optimal point for intervention.
Before Your Test
Preparation & Safety
Medications to Discuss
- Beta-blockers (bisoprolol, atenolol, carvedilol, metoprolol) must be withheld for 48 hours before the test — they prevent the heart from reaching target rate and will make the test non-diagnostic
- Rate-limiting calcium channel blockers (diltiazem, verapamil) should also be discussed with Dr Nijjer before the appointment
- All other medications, including aspirin and statins, should be continued as normal
- Avoid caffeine on the morning of the test
On the Day
- Do not eat a heavy meal for at least two hours before the test
- Wear comfortable clothing; trainers suitable for walking are required if an exercise protocol is being used
- An intravenous cannula will be sited in your arm before the test begins for dobutamine delivery or emergency access
- ECG monitoring continues throughout the procedure and during recovery
- The entire appointment typically takes 60–90 minutes
Safety: Serious complications are rare — approximately 1 in 1,000 for dobutamine stress echo. Transient side effects during dobutamine infusion (chest tightness, palpitations, flushing, or mild breathlessness) are common and resolve immediately when the infusion is stopped. A consultant cardiologist and resuscitation equipment are present throughout. The test is stopped at the first sign of any significant abnormality.
Understanding Your Findings
What the Results Mean
Negative result
Normal — No Ischaemia Detected
All segments of the heart muscle show normal, coordinated contraction at peak stress. This is strongly reassuring and associated with a very low risk of cardiac events (<1% per year). In most patients, this finding removes the need for further invasive testing and allows Dr Nijjer to focus on medical risk-factor management.
Positive result
Ischaemia Identified
New wall motion abnormalities appearing at stress — segments that contract normally at rest but poorly under demand — indicate ischaemia in the territory supplied by a narrowed coronary artery. The location and extent of the ischaemia guides the decision about whether medical treatment or invasive coronary angiography and possible stenting is the appropriate next step.
Chest Pain or Breathlessness
Under Exertion?
Stress echocardiography provides a definitive answer when symptoms suggest coronary artery disease. Dr Nijjer personally performs and reports every study.