Tiny gas bubbles could help identify people at risk of a life-threatening heart attack.
Once injected into the bloodstream, the movement of the bubbles can be tracked with an ultrasound probe and if they slow or stop, this could suggest that there is a potentially dangerous blockage that needs to be removed immediately.
A new study testing the technique on four patients by Imperial College London has shown promise.
Many patients admitted to the emergency room with chest pain often discover, after a long series of tests, that they do not actually have heart problems.
The hope is that bubble injection could eventually be used in busy emergency departments to quickly identify whether patients with chest pain require urgent treatment to clear a blockage, or whether something else is causing it.
More than seven million people in the UK suffer from heart disease, a condition in which the blood vessels supplying the heart become narrowed or blocked, largely due to the build-up of fatty deposits.
When blood flow to the heart is interrupted, it can cause sharp chest pain that may indicate a heart attack. This requires urgent medical treatment (with blood-thinning medications, for example, or with a typically metal tube called a stent to open a blockage).
But about half of all patients who come to the ER with chest pain don’t actually have heart problems.
Instead, your discomfort usually has to do with other problems, such as severe heartburn, anxiety, or a peptic ulcer (a painful sore in the lining of the stomach or esophagus).
Despite this, the majority of these patients initially end up undergoing lengthy check-ups to rule out a heart attack.
Under current NHS guidelines, patients with a suspected heart attack should have their blood tested for a protein called troponin as soon as they arrive at hospital. These “cardiac enzymes” are released at high levels by the heart muscle as a result of a heart attack.
A second troponin test is then performed at least three hours later to verify the results of the first.
Patients remain in the hospital under close supervision while the results are checked. Only then, after several hours, are they sent home or referred back to their GP if their heart is given the all-clear.
Those with a high troponin score are usually referred for angiography, in which a special dye is injected (under local anesthesia) into the bloodstream and tracked with x-rays as it flows through the body, highlighting any blockages.
The procedure, tested on four people by Imperial College London, involved injecting thousands of bubbles into the bloodstream and then tracking them using an ultrasound device.
The new test, which takes just a few minutes, could speed up the detection of clogged arteries and free up NHS beds occupied by patients whose pain is not actually heart-related.
In a study at Imperial College London, the technology was tested on four patients with a history of heart disease. For this simple procedure, thousands of bubbles are mixed with a salt water solution and slowly injected into a vein through a small incision made in the patient’s arm.
After a few minutes, a handheld ultrasound probe is passed over the patient to monitor the bubbles as they pass through the blood vessels around the heart.
The sound waves bounce off the bubbles and become a computer image that details how well they move through blood vessels.
The results of the study, published in the journal Nature Biomedical Engineering, showed that the scan caught all the microscopic bubbles as they navigated through even the smallest arteries.
Separate tests, using pig hearts, also showed that arteries where the bubbles had slowed, stopped or converged in the middle of the blood vessel (indicating fatty deposits in the walls) were blocked or partially blocked.
Dr Klaus Witte, consultant cardiologist at Leeds Teaching Hospitals NHS Trust, says hospitals need faster ways to diagnose heart problems and this “bubble technique could help” solve the problem.
Commenting on the technology, Dr Klaus Witte, consultant cardiologist at Leeds University Hospitals NHS Trust, said the test “is very interesting”.
“More than half of all emergency room visits for chest pain are not due to the heart,” he added.
“We need a quick and easy way to detect people with a potentially life-threatening heart problem, and this technique could help.”