Blood Flow Imaging May Aid Cardiomyopathy Diagnosis

Engineers at the University of California, San Diego (UCSD) say they have determined for the first time the impact of a ring-shaped vortex on transporting blood flow in normal and abnormal ventricles within the human heart. They worked with cardiologists at the Non-Invasive Cardiology Laboratory at Gregorio Marañon Hospital, in Madrid, Spain.

In order to make the study possible, researchers developed a novel ultrasound technology that makes screening cheaper and much easier, making it possible to reach a large number of people and even infants. Intraventricular flow imaging is currently done with MRI scans, which is expensive and not suitable for many patients with implanted devices such as pacemakers.

Researchers say the findings could have an impact on the tests and measurements physicians rely on to diagnose and treat two heart conditions: hypertrophic cardiomyopathy, in which the heart muscle becomes abnormally thick, and nonischemic dilated cardiomyopathy, in which the heart's ability to pump blood decreases as the organ's main pumping chamber, the left ventricle, is enlarged and its muscle thinned. Nearly 1 million Americans suffer from one of these conditions.

So far, physicians only take into consideration the geometry of the left ventricle and the thickness and contractility of its walls when they assess how the heart fills itself with blood. But the way the blood flows into the heart's chambers is important too, researchers argue. "This isn't like toothpaste coming out of a tube," says Juan Carlos del Alamo, AeEng, PhD, a professor of mechanical and aerospace engineering at the Jacobs School of Engineering at UCSD, who led a multidisciplinary team for this study, together with postdoctoral researcher Pablo Martinez-Legazpi, MEng, PhD, and Javier Bermejo, MD, PhD, and his group of cardiologists at Gregorio Marañon Hospital.

They reported their findings in the October 21 issue of the Journal of the American College of Cardiology.

People suffering from hypertrophic and dilated cardiomyopathies often don't show symptoms of the condition until it's too late—making early screening of paramount importance. When patients are not diagnosed early, these conditions have unfavorable prognosis, with most of the patients dying within five years.

For this study, the team of cardiologists recruited 60 subjects, including 20 patients with nonischemic dilated cardiomyopathy, 20 patients with hypertrophic cardiomyopathy, and 20 healthy subjects as a control group.

All subjects underwent comprehensive 2D echocardiographic exams. Then, engineers processed the images with methods typically used to create flow simulations for the aeronautical and naval industries, capturing the blood flow inside each subject's heart.

Researchers found that the ring-shaped vortex helps to allocate about 15% of the blood flow within the left ventricle in healthy patients, roughly 20% in patients with nonischemic dilated cardiomyopathy, but only about 5% for patients with hypertrophic cardiomyopathy.

Treatment therapy for cardiomyopathies often includes devices implantation, such as pacemakers, to regulate blood flow within the heart. The data from these new imaging modalities could be instrumental, helping physicians to properly set up the devices, optimizing blood flow.