A bubble echo is not dangerous for the vast majority of people. It is one of the safest diagnostic heart tests available, with serious complications occurring in roughly 1 in 10,000 cases. Most people feel nothing unusual during or after the procedure, and you can drive yourself home and resume normal activities immediately.
What a Bubble Echo Does
A bubble echo, formally called an agitated saline contrast echocardiogram, is an ultrasound of the heart that uses tiny air bubbles to check for holes between heart chambers. A small amount of saline (salt water) mixed with about half a milliliter of air is rapidly pushed back and forth between two syringes to create microbubbles, then injected into a vein in your arm.
Those bubbles travel through the bloodstream to the right side of the heart, where they show up clearly on the ultrasound image. In a normal heart, the lungs filter out every bubble before blood returns to the left side. If bubbles appear on the left side, it signals an opening between the chambers, most commonly a patent foramen ovale (PFO), a small flap-like gap that never fully closed after birth. Doctors order this test frequently in younger patients who have had an unexplained stroke, since a PFO can allow tiny blood clots to bypass the lungs and reach the brain.
During the test you may be asked to bear down (a Valsalva maneuver) or cough. These actions briefly raise pressure on the right side of the heart, making it easier to detect even small shunts. The entire procedure typically takes about 15 to 20 minutes.
Common Side Effects
Most people experience no side effects at all. When minor reactions do occur, they are usually limited to a brief cool sensation or mild discomfort at the IV site as the saline is injected. Some people notice a fleeting lightheaded feeling or a slight metallic taste. These sensations resolve within seconds to minutes and do not require any treatment.
How Rare Serious Reactions Are
The numbers on serious complications are reassuring. In a study of more than 78,000 contrast echocardiograms compiled by the American Society of Echocardiography, only eight serious adverse events were recorded, a rate of 0.01%. Four of those were allergic-type (anaphylactoid) reactions, putting that specific risk at roughly 1 in 17,000. No fatalities occurred. A separate review of over 16,000 patients at a single medical center found a serious adverse event rate of 0.03%, again with zero deaths.
The one complication that gets the most attention is the possibility of a transient neurological event, such as brief numbness, vision changes, or, very rarely, a small stroke. A survey by the American Society of Echocardiography estimated transient side effects occur in about 0.062% of cases. A multi-institution case review identified five patients across four hospitals who experienced ischemic events (three strokes and two transient ischemic attacks) in connection with the test. These events are believed to happen when air bubbles cross through an existing hole in the heart and temporarily reach the brain’s blood supply. Importantly, the bubbles used in this test are extremely unstable, meaning they dissolve quickly in the bloodstream.
How It Compares to Other Contrast Methods
There are two broad categories of contrast used in echocardiography. The agitated saline bubble study uses plain salt water and air. Commercial ultrasound contrast agents use manufactured microbubbles filled with heavier gases and enclosed in stabilizing shells. These commercial agents are FDA-regulated and primarily used to get better images of the heart’s pumping function, not to look for shunts.
Interestingly, agitated saline studies are not regulated by the FDA at all, largely because saline and room air are not considered drugs. Despite delivering a relatively large volume of air-filled microbubbles into the circulation, transient neurological symptoms remain rare. Commercial contrast agents have no documented cases of acute neurological complications, likely because their bubbles are far smaller and more contained. Both types carry an extremely low overall risk profile.
Safety During Pregnancy
For a long time, there was almost no data on whether bubble studies were safe for pregnant patients. A 2025 study published in JACC: Advances examined 100 pregnant individuals who underwent agitated saline echocardiograms. None experienced air embolism, fetal distress, or any maternal or fetal complications within 24 hours of the test. While the sample size is modest, the findings support the position that the test is safe during pregnancy when clinically needed.
What to Expect Afterward
Recovery from a bubble echo is essentially immediate. Once the ultrasound probe is removed and the IV is taken out, you get dressed and leave. There are no activity restrictions, no observation period, and no driving limitations. You do not need someone to accompany you. The microbubbles dissolve completely within minutes, and the saline is simply absorbed by the body like any other IV fluid. If your doctor identifies a shunt or other finding, the follow-up plan will depend on what was found and your overall health picture, but the test itself requires nothing further from you.