A heart valve that looks only mildly abnormal may already be affecting the timing of the heartbeat, according to new research.
Scientists have used an advanced ultrasound method to detect subtle changes in people with mitral valve disease, including children with relatively mild conditions.
The finding could change how doctors think about mitral valve prolapse and mitral regurgitation. Instead of being problems involving only the valve, these conditions may also affect how nearby heart muscle receives and responds to electrical signals.
The mitral valve is located on the left side of the heart. Its job is simple but essential: keep blood moving in the correct direction as the heart fills and pumps.
In mitral valve prolapse, part of the valve bulges backward when the heart contracts. In mitral regurgitation, the valve allows some blood to leak backward instead of sending all of it forward into the body’s main artery.
Many cases are mild and can be monitored for years. Some people never develop major problems, while others eventually experience worsening leakage, changes in heart size or abnormal rhythms.
One of the biggest challenges is knowing who is at risk of serious complications. Certain forms of mitral valve disease have been associated with dangerous rhythms arising from the lower chambers of the heart.
Researchers at Columbia Engineering wanted to see whether they could detect warning signs hidden within the timing of each heartbeat. Their tool, Electromechanical Wave Imaging, or EWI, adds a new type of information to a familiar heart test.
Most people who have had a heart ultrasound know it as an echocardiogram. A probe placed on the chest sends harmless sound waves into the body and uses the returning echoes to create moving images of the heart.
Doctors can use these images to see whether valves open and close properly, whether blood is leaking and how well the heart muscle is pumping. Yet a standard scan does not directly map the sequence linking the heart’s electrical signal with the movement of its muscle.
EWI was developed to examine that connection. It tracks extremely small movements in the heart at very high speed, allowing researchers to follow how activation spreads through the muscle.
The work was led by Elisa Konofagou, a professor of biomedical engineering at Columbia University. Her team collaborated with Columbia NewYork-Presbyterian Pediatric Cardiology and the Institute of Cardiovascular Sciences at University College London.
The researchers studied 21 younger participants whose hearts were healthy or affected by MVP or MR. Studying children and young people helped the team examine valve disease before decades of other heart conditions could complicate the picture.
Two adults with a more dangerous form of MVP were also included. These patients had already developed abnormal rhythms in the heart’s lower pumping chambers.
The researchers found that MVP was linked with slower activation in the left ventricle, the powerful chamber that pumps oxygen-rich blood around the body. The delay was especially noticeable near the papillary muscles.
These small muscles are closely connected with the mitral valve and help keep it stable as the heart squeezes. Because they sit where the valve and heart muscle work together, changes in this region may be particularly important.
Participants with even mild MVP and MR took longer than healthy participants to complete the heart’s full activation and recovery process. People with MR had longer recovery times than those with MVP.
That finding suggests that changes may begin earlier in valve disease than doctors can easily see with conventional imaging. A valve problem that appears mild structurally may still be associated with changes in the timing and coordination of the surrounding heart muscle.
The adult cases provided another clue. During a single ultrasound examination, the researchers detected spontaneous abnormal beats and traced them to areas that also showed delayed normal activity.
Being able to locate such a problem without putting a catheter inside the heart could eventually be useful. Doctors currently use several tests to investigate abnormal rhythms, and some detailed electrical mapping procedures are invasive.
The new technique is not ready to replace those methods. The research involved a small number of people, and only two adults in the study had the serious rhythm condition that is of greatest concern.
Large studies will be needed to determine whether EWI can reliably identify patients who will later develop dangerous arrhythmias. Researchers will also need to establish normal ranges for different ages and heart conditions.
Another unanswered question is whether finding an early delay should change treatment. Detecting an abnormality is useful only if doctors know what it means and can use that information to improve outcomes.
The research was published in the Proceedings of the National Academy of Sciences. It supports a broader view of mitral valve disease in which the valve, heart muscle and electrical activity are closely connected rather than separate issues.
The study’s main strength is that the technique extracts additional information from ultrasound, a familiar and widely used form of heart imaging. If EWI can eventually be built into standard scanners, it may be easier to bring into routine care than a completely separate imaging system.
Its main limitation is the early stage of the evidence. The results are promising, but they cannot yet tell doctors exactly who is at risk of sudden cardiac problems or whether treatment based on EWI findings would prevent them.
The team now plans to test the approach in larger groups and integrate it into clinical ultrasound equipment. If those efforts succeed, a future echocardiogram could potentially show not only what the heart looks like and how it pumps, but also whether the timing of its electrical and mechanical activity is beginning to go wrong.
Source: Columbia University.
