Patient guide · Cardiology
Bubble echocardiogram, agitated-saline contrast echo for patent foramen ovale and paradoxical embolism.
A bubble study (agitated saline contrast) is an echocardiogram in which tiny microbubbles are injected into a peripheral vein and imaged crossing the heart. Detects patent foramen ovale (PFO) and pulmonary arteriovenous malformations — key in cryptogenic stroke, decompression illness and platypnoea-orthodeoxia.
Reviewed 2026-07-30 by Pulse Atlas Editorial Board, · 6-minute read · Next review 2027-07-30
Why patients choose us
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The right hands
We route you to a consultant cardiologist with dedicated bubble-echo experience — the person who scans and reads decides the answer.
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Often answers same-day
A bubble study is a short extension of a standard echocardiogram; findings can usually be discussed on the same visit.
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Independent, and free
We are paid by no clinic, so the recommendation is impartial and costs you nothing.
Key facts
What a bubble echocardiogram is — and isn’t.
A short bedside test with a specific job: to detect a right-to-left shunt when clinical context — usually stroke, hypoxia or diving history — makes one likely.
| Aspect | In one line |
|---|---|
| Definition | Agitated-saline contrast echo to detect right-to-left shunt. |
| When it’s done | Same-day extension of a routine echocardiogram. |
| What it detects | Patent foramen ovale (PFO), atrial septal defect, pulmonary AVM. |
| Sensitising manoeuvre | Performed with Valsalva to increase sensitivity. |
| Key indication | Central investigation in cryptogenic-stroke workup. |
| Complements | Transoesophageal echocardiogram (TOE) for anatomical detail. |
How it’s done
From cannula to report — what happens, in order.
Seven steps, usually completed in a single visit lasting under an hour.
Phase 1 · Preparation
Consultation and IV access
Phase 2 · The study
Echo, injection, Valsalva, views
Phase 3 · Report
Same-day discussion
- 01
Preparation
Cardiology consultation
A consultant cardiologist confirms the indication, reviews prior imaging and consents you for the study.
- 02
Preparation
Peripheral IV line inserted
A small cannula is placed, usually in the left arm, to deliver the agitated saline.
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The study
Baseline echocardiogram
Standard transthoracic echo views are recorded before any contrast is given.
- 04
The study
Agitated saline / contrast injected
Saline is agitated between two syringes to create microbubbles, then injected rapidly through the cannula.
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The study
Valsalva manoeuvre during injection
You bear down as the bubbles arrive — this transiently raises right-atrial pressure and unmasks a PFO.
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The study
Multiple views recorded
Apical four-chamber and subcostal views capture bubble transit across the septum and through the lungs.
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Report
Report same day
The reporting cardiologist discusses findings and, if needed, arranges TOE or a cryptogenic-stroke MDT referral.
Typical time on the day: 45–60 minutes. Written report: same day.
What it shows
What a bubble echo can — and can’t — answer.
Bubble timing and count carry the diagnosis. The presentations we see most, and the one that changes the pathway immediately.
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Right-to-left shunt
Early bubble appearance in the left heart confirms a right-to-left shunt.
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Patent foramen ovale (PFO)
Immediate transit within 3 cardiac cycles typically indicates a PFO.
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Atrial septal defect (ASD)
A persistent, high-volume shunt with structural features suggests ASD.
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Pulmonary arteriovenous malformation
Delayed bubble appearance (after 4–6 cycles) points to a pulmonary AVM.
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Timing of bubble transit
Number of cardiac cycles before left-heart opacification differentiates cardiac from pulmonary shunt.
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Shunt severity (bubble count per cycle)
Small (<10), moderate (10–30) and large (>30) shunts are graded semi-quantitatively.
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Contrast-enhanced ventricular assessment
Contrast improves endocardial border delineation for LV function assessment.
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Red flag: large shunt + cryptogenic stroke — PFO-closure MDT referral
A large right-to-left shunt in the context of cryptogenic stroke is a same-week MDT decision.
Next steps
What follows a bubble echocardiogram.
Whether the study is positive or negative, the plan is set alongside neurology, stroke or respiratory teams as appropriate.
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Reassurance if negative
A negative bubble study with negative Valsalva effectively excludes a haemodynamically significant right-to-left shunt.
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Cardiology follow-up
Structured follow-up to review findings alongside imaging, ECG and stroke workup.
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TOE for detailed anatomy
Transoesophageal echo characterises septal anatomy, atrial septal aneurysm and rim adequacy for device closure.
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Cryptogenic stroke MDT review
Joint neurology–cardiology decision on closure versus long-term antiplatelet/anticoagulant therapy.
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PFO closure with device
Percutaneous closure with an Amplatzer or GORE Cardioform device in selected patients under 60.
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Anticoagulation for high-risk cases
Anticoagulation is preferred when a concurrent hypercoagulable state or atrial fibrillation is identified.
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Investigate pulmonary AVM (chest CT)
A delayed shunt prompts contrast-enhanced chest CT to map pulmonary AVMs for embolisation planning.
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Neurology follow-up
Ongoing neurology review after stroke or TIA to monitor recurrence and secondary-prevention targets.
Red flags and indications
When a bubble echo is the right test.
Nine contexts in which the shunt question needs an answer — and one caution to flag before you attend.
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Cryptogenic stroke
A stroke with no identified conventional cause in a patient under 60 — a core bubble-study indication.
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Recurrent TIA
Repeated transient ischaemic attacks despite antiplatelet therapy warrant a shunt search.
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Migraine with aura (unclear role)
An association with PFO exists; closure for migraine alone is not standard of care.
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Decompression illness in divers
Divers with unexplained decompression sickness are routinely screened for PFO.
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Platypnoea-orthodeoxia
Positional hypoxia — dyspnoea and desaturation on standing — is a classic bubble-study indication.
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Hereditary haemorrhagic telangiectasia
HHT patients are screened for pulmonary AVMs, often first detected on bubble echo.
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Post-PFO-closure device thrombosis
A concern after percutaneous closure; bubble study confirms residual or new shunt.
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Post-cardiac-catheter shunt
Bubble echo helps evaluate iatrogenic shunts after septal puncture procedures.
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Contrast allergy
Rare with agitated saline, but any prior reaction must be flagged before the study.
Sources
Every claim on this page is traceable.
Guidance drawn from NICE and the major cardiology and echocardiography societies.
- 01 Reference
NICE. Percutaneous closure of patent foramen ovale to prevent recurrent cerebral embolic events (IPG472).
- 02 Reference
European Society of Cardiology. Position paper on management of patent foramen ovale.
European Society of Cardiology. Position paper on management of patent foramen ovale.
- 03 Reference
British Society of Echocardiography. Guidelines and minimum dataset for contrast echocardiography.
British Society of Echocardiography. Guidelines and minimum dataset for contrast echocardiography.
- 04 Reference
American Society of Echocardiography. Guidelines for the use of echocardiographic contrast agents.
American Society of Echocardiography. Guidelines for the use of echocardiographic contrast agents.
Frequently asked
Everything we get asked about bubble echocardiograms.
Quick answers on safety, indications, the Valsalva manoeuvre, PFO versus ASD, and what a positive study means.
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What is a bubble echocardiogram?
A bubble study is an echocardiogram in which agitated saline — a suspension of tiny microbubbles — is injected into a peripheral vein and imaged as it crosses the heart. It is the standard bedside test for detecting a right-to-left shunt.
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Why would I need a bubble study?
The commonest indications are cryptogenic stroke or TIA (looking for a patent foramen ovale), decompression illness in divers, platypnoea-orthodeoxia, and screening for pulmonary arteriovenous malformations in hereditary haemorrhagic telangiectasia.
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Is agitated saline safe?
Agitated saline is one of the safest contrast agents used in cardiology — it is simply sterile saline with air microbubbles. Adverse events are rare and typically limited to transient flushing.
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What is the Valsalva manoeuvre for?
Bearing down transiently raises right-atrial pressure so that any patent foramen ovale opens under strain. Without a good Valsalva, the study can miss a clinically important PFO.
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How is a PFO different from an ASD?
A PFO is a persistent flap-like remnant of fetal circulation, present in around a quarter of adults. An ASD is a true structural defect in the atrial septum with a fixed left-to-right shunt.
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What happens if the study is positive?
A positive study is discussed at a cardiology or joint neurology–cardiology MDT. Options include a transoesophageal echo for detailed anatomy, percutaneous PFO closure, or long-term anticoagulation depending on the clinical context.
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In practice, in London
Getting bubble echocardiogram sorted in London, without the guesswork
With bubble echocardiogram, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. Waiting lists on the NHS for bubble echocardiogram vary widely by borough and by how the GP letter reads. Privately in London, we can normally offer a slot inside the same week, sometimes within 48 hours if there’s a cancellation. The difference isn’t clinical quality — the consultants are frequently the same faces you’d see on the NHS — it’s the calendar.
A typical private booking for bubble echocardiogram in London starts with a consultant conversation — sometimes in person on Harley Street or Marylebone, sometimes on video if that suits better. Any imaging or diagnostics happen at a nearby CQC-registered facility, and reports usually land within 24 to 72 hours. The whole loop, from first call to written report, is often done inside a fortnight. For bubble echocardiogram specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
The value of going through a concierge for bubble echocardiogram isn’t access — anyone with an insurer or a credit card can get a private appointment in London. The value is knowing which consultant reads this particular presentation best, which unit turns reports around fastest, and which pathway won’t hit a dead end if the findings point somewhere unexpected.