A new type of heart ultrasound may reveal dangerous changes that ordinary scans cannot see.
Researchers at Columbia University say the technique could eventually help doctors identify people with mitral valve disease who are at risk of abnormal heart rhythms.
The mitral valve sits between two chambers on the left side of the heart. It opens to let blood move forward and then closes to stop blood from flowing backward when the heart squeezes.
Problems with this valve are common. Mitral valve prolapse, or MVP, happens when part of the valve bends backward during a heartbeat, while mitral regurgitation, or MR, occurs when the valve does not close tightly enough and blood leaks in the wrong direction.
These conditions are often mild, and many people may have few symptoms. But in some patients, mitral valve disease can become more serious and may be linked with abnormal heart rhythms.
Rarely, dangerous rhythm problems can contribute to sudden cardiac death. Doctors therefore want better ways to identify which patients are likely to remain stable and which may need closer monitoring or treatment.
Standard echocardiograms are one of the main tools used to examine valve disease. An echocardiogram uses sound waves to create moving pictures of the heart, allowing doctors to see the valve, measure blood flow and examine how strongly the heart pumps.
But the heart is not only a mechanical pump. Every heartbeat begins with an electrical signal that spreads through the heart muscle and tells different areas when to contract.
Researchers led by Elisa Konofagou at Columbia Engineering have developed a method called Electromechanical Wave Imaging, or EWI. It uses information from ultrasound images to track the tiny movements that occur as electrical signals trigger the heart muscle to contract.
This allows researchers to study the timing of electrical and mechanical activity across the heart without inserting instruments into the body. The goal is to detect subtle delays or unusual patterns that conventional scans may miss.
In the new study, the researchers worked with Columbia NewYork-Presbyterian Pediatric Cardiology and scientists at University College London. They examined whether EWI could detect unusual heart activity in people with mitral valve problems.
The clinical part of the study included 21 children and young people with healthy hearts, MVP or MR. The researchers also examined two adults who had a form of MVP associated with abnormal heart rhythms.
The results showed clear differences in timing. People with MVP had delayed activation in the heart’s left lower pumping chamber, especially around structures called papillary muscles.
Papillary muscles play an important role in helping the mitral valve close correctly. They are connected to the valve by strong, cord-like structures and move as the heart contracts.
Even participants with mild MVP or MR showed longer times for the heart to complete its cycle of activation and recovery compared with healthy participants. This suggests that changes in the heart muscle may appear before valve disease becomes severe.
People with MR showed particularly long recovery times. Recovery is important because heart cells need to reset after each beat before they can respond normally to the next electrical signal.
The researchers also wanted to know whether the method could find where abnormal heartbeats began. In the adults with rhythm problems, EWI was able to locate spontaneous abnormal activity during a single ultrasound examination.
The areas producing the unusual beats were found near regions where the heart’s normal electrical and mechanical response was delayed. Additional laboratory studies supported the clinical findings.
This is potentially important because locating the source of an abnormal rhythm can sometimes require more complicated testing. A noninvasive ultrasound method that provides this information could make assessment easier if future studies confirm its accuracy.
Konofagou said the technology may help doctors view mitral valve disease as more than a structural problem involving the valve alone. The valve, heart muscle and electrical system may influence one another as disease develops.
The study was published in the Proceedings of the National Academy of Sciences. It provides early evidence that EWI can reveal changes in heart timing that are not readily visible with standard clinical imaging.
However, the study was small, particularly the part involving patients with serious rhythm problems. Results from 21 younger participants and two affected adults are not enough to show how accurately the method can predict dangerous events in the wider population.
The technology also needs to prove that finding these early delays changes patient care in a useful way. A test is most valuable when it can reliably identify people who need treatment while avoiding unnecessary worry and procedures in those at low risk.
The researchers plan to study much larger groups and work toward adding EWI to clinical ultrasound machines. If those studies are successful, doctors might eventually obtain information about the heart’s structure, pumping action and electrical timing during the same examination.
Overall, the study offers an intriguing new way to examine mitral valve disease. Its greatest promise is not that it replaces today’s heart tests, but that it may add an extra layer of information that helps doctors see hidden electrical problems before they become more serious.
Source: Columbia University.
