Bubble Echo: Contrast Echocardiogram for a Hole in the Heart
Consultant-led bubble study to look for a patent foramen ovale
Arrange a bubble echo (agitated saline contrast echocardiogram) with Consultant Cardiologist Dr Salam Salloum (GMC 5209498), who holds British, European and American board certifications in echocardiography.
A bubble echo is an ultrasound scan of the heart with a harmless saline solution containing tiny bubbles injected into a vein. It shows whether blood passes through a small opening between the right and left sides of the heart, such as a patent foramen ovale (PFO).
Available at Innovate Diagnostics, Corby, and at The National Heart Clinic, 69 Harley Street, London W1G 8QW. You can self-refer without a GP letter.
Price on enquiry
What is a bubble echo?
A bubble echo, also called a contrast echocardiogram or bubble study, is a standard echocardiogram with an added test. A small amount of saline is shaken (agitated) to create microscopic bubbles, which are injected through a cannula into an arm vein. The bubbles are bright on ultrasound and travel to the right side of the heart.
Normally the bubbles are filtered out by the lungs and do not reach the left side of the heart. If the bubbles appear on the left side, there is a connection through which blood can bypass the lungs.
Why might you need a bubble echo?
The test is used to look for a right-to-left shunt, most often a patent foramen ovale. It may be recommended for:
- A stroke or transient ischaemic attack (TIA) with no clear cause, particularly in people under 60
- Migraine with aura, in selected cases, after specialist advice
- Decompression illness in divers, or before returning to diving
- Low oxygen levels with no clear explanation, or breathlessness that worsens on sitting up or standing
- A suspected abnormal connection in the lungs (pulmonary arteriovenous malformation)
- Follow-up after a heart or lung procedure
A PFO is a small flap-like opening that is present before birth and remains open in roughly one in four adults. Most people with a PFO never have any problem.
Bubble echo for divers
A patent foramen ovale (PFO) is a small flap-like opening between the upper chambers of the heart that stays open in about one in four adults. In most people it causes no problems. After a dive, small nitrogen bubbles normally pass through the veins and are filtered out by the lungs. If there is a significant right-to-left shunt, some bubbles can cross to the arterial side and reach the brain, spinal cord, inner ear or skin. This is linked to a higher risk of certain types of decompression illness.
The joint position statement of the South Pacific Underwater Medicine Society (SPUMS) and the UK Diving Medical Committee (2025) advises that:
- Routine screening of all divers is not recommended.
- Testing should be considered after decompression illness affecting the brain, spinal cord, inner ear, heart or skin, and in divers with migraine with aura, a previous stroke with no clear cause, a close relative with a PFO or atrial septal defect, or congenital heart disease.
- The test should be a bubble contrast echocardiogram with provocation manoeuvres, such as release of a Valsalva strain and sniffing. Standard echocardiography and colour Doppler alone are not enough.
- The size of the shunt is graded by counting the bubbles that reach the left side of the heart (small, medium or large), and this affects the advice.
If a shunt is found and judged to raise your risk, the options include stopping diving, diving more conservatively (for example limiting depth, staying well within no-decompression limits and allowing longer safety stops), or considering closure of the PFO through a catheter. After closure, the guidance advises a repeat bubble echo at least three months later to confirm that the shunt has gone or has been greatly reduced before you return to diving.
Please bring your dive log, any hyperbaric treatment records and letters from your diving doctor. Decisions about returning to diving should be made with a diving medicine physician; this page does not replace that advice.
What does the test show?
- Whether bubbles cross from the right to the left side of the heart, and how many
- The timing of the bubbles: those appearing within the first few heartbeats suggest a hole in the heart, whereas bubbles that appear later suggest a connection in the lungs
- The size of the shunt, graded as small, moderate or large
- Whether the shunt increases with a cough or the Valsalva (bearing-down) manoeuvre
- Other heart findings from the standard echocardiogram, including pumping function, valves and chamber size
What happens during the appointment?
- A small cannula is placed in a vein in your arm.
- You lie on your left side with ECG stickers on your chest, and the heart is scanned as in a standard echocardiogram.
- The saline bubbles are injected while the heart is scanned. You are asked to cough or to bear down (Valsalva) at set moments, as this reveals a PFO that may only open briefly.
- The injection is repeated once or twice.
The scan usually takes 30 to 45 minutes, and the appointment about an hour. You can eat, drink, take your medicines and drive as normal afterwards.
How to prepare
- There is no need to fast, and you should take your medicines as normal.
- Wear a loose two-piece outfit that is easy to change.
- Bring any previous scan reports, letters from a neurologist or stroke team, or diving records.
- Tell us if you have a known large hole in the heart, a pulmonary arteriovenous malformation, a low oxygen level, or if you might be pregnant.
Is a bubble echo safe?
The test is safe. The bubbles are tiny and dissolve, and are cleared by the lungs. The injection feels like having a blood test. Serious side effects are rare. Because the bubbles contain air, extreme care is taken to avoid any large air bubbles, and the test is performed by a trained cardiologist.
Your results and next steps
Dr Salloum reviews the images and provides a written report. If a PFO is found, he explains what it means for you. In many people no treatment is needed. After an unexplained stroke or TIA, a decision about closing a PFO is made together with a stroke specialist, because closure is helpful only for selected people, usually younger people in whom the PFO is the most likely cause. If the bubble study is unclear, a transoesophageal echocardiogram (a camera passed through the throat) may be suggested.
You can discuss results in a face-to-face, video or telephone consultation.
Limitations of a bubble echo
- Some people cannot perform the Valsalva manoeuvre well enough, which can lead to a false negative result.
- A transthoracic bubble study can be less accurate than a transoesophageal study for small shunts.
- Finding a PFO does not prove that it caused a stroke or migraine.
Cost and booking
The cost of a bubble echo depends on the site. Please contact us for a fee, and we will confirm the total cost before you book. A consultation to discuss your results is charged separately. Dr Salloum is recognised by several major insurers; please check your cover before booking.
Corby appointments are held at Innovate Diagnostics, Corby Innovation Hub, Bangrave Road South, Weldon, Corby NN17 1NN.
Related services
Important limitations
- A bubble echo is a planned outpatient test, not an emergency service.
- If you have symptoms of a stroke, such as sudden weakness, facial droop, speech difficulty or loss of vision, call 999 immediately.
- The result must be interpreted with your symptoms and other tests.
If you develop severe or persistent chest pain, marked breathlessness or collapse, call 999 or attend the nearest emergency department.
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Bubble echo FAQs
Where is the bubble echo performed?
Bubble echo is available at Innovate Diagnostics in Corby and in London. The London clinic is The National Heart Clinic, 69 Harley Street, London W1G 8QW.
What is a bubble echo?
A bubble echo is an ultrasound scan of the heart with saline bubbles injected into a vein. It shows whether blood passes through an opening between the right and left sides of the heart, such as a patent foramen ovale (PFO).
What is a patent foramen ovale (PFO)?
A PFO is a small flap-like opening between the upper chambers of the heart that is normal before birth and stays open in roughly one in four adults. Most people never know they have one.
Is a bubble echo painful?
No. You feel a small scratch when the cannula is placed. The bubbles are not felt when they are injected.
How long does a bubble echo take?
The scan takes about 30 to 45 minutes, and the whole appointment around an hour.
Is a bubble echo safe?
Yes. The bubbles are tiny and are filtered out by the lungs. Side effects are rare.
Why do I need to cough or bear down during the test?
Coughing and bearing down (Valsalva) briefly raise the pressure in the right side of the heart. This opens a PFO that may be closed at rest and makes the test more accurate.
Will a PFO need to be closed?
Many people with a PFO need no treatment. Closure may be considered in selected younger people who have had a stroke with no other clear cause. The decision is made with a stroke specialist.
Do I need a GP referral for a private bubble echo?
No. Self-funded patients can usually self-refer. If you use private medical insurance, check with your insurer first.
Can a bubble echo help with migraine or diving?
A bubble echo can show whether you have a PFO, which is more common in people with migraine with aura and in divers with decompression illness. Whether treatment is helpful depends on your circumstances and needs specialist advice.
Do I need a bubble echo before diving?
Not routinely. Current UK and Australasian diving medicine guidance does not recommend screening every diver. A bubble echo is usually considered after decompression illness affecting the brain, spinal cord, inner ear, heart or skin, or if you have migraine with aura, a previous unexplained stroke, a close relative with a PFO, or congenital heart disease.
Can I still dive if I have a PFO?
Many people with a PFO dive without problems. If a bubble echo shows a shunt that raises your risk, the options include stopping diving, diving more conservatively, or considering closure of the PFO. The right choice depends on your history and the diving you do, and should be made with a diving medicine physician.