Forget the ultrasound. Detailed information about one’s heart health can be obtained from a smartphone camera.
A proof-of-concept clinical trial involving engineers from Caltech, Huntington Medical Research Institute (HMRI) and USC demonstrated an ability to noninvasively collect heart health data simply by holding a phone up to a subject’s neck for 1-2 minutes. The technique uses an app to measure displacement on the skin caused by blood pumping through the carotid artery. This infers the left ventricular ejection fraction (LVEF) of the heart – a measurement of the amount of blood pumped out with each beat.
In a normal heart, the LVEF ranges from 50 to 70 percent. When the heart is weaker, less of the total amount of blood in the heart is pumped out with each beat, resulting in a lower LVEF value. The LVEF is a key measure of heart health, one on which doctors base diagnostic and therapeutic decisions. The value is typically measured by ultrasound echocardiography, which requires a trained technician, a costly machine and up to 45 minutes of a patient’s time.
To test their app, researchers conducted clinical trials with 72 volunteers between the ages of 20 and 92. They validated their findings by comparing them to those obtained through a magnetic resonance imaging (MRI) exam. MRI is considered the gold standard for LVEF measurement, but is seldom used due to its high cost and limited availability. The measurements made by smartphone had a ± 19.1 percent margin of error when compared to those done in an MRI; while that might sound high, the margin of error for echocardiography is around ± 20.0 percent.
"What is exciting about this study is that it shows our technique is as accurate as echocardiography at estimating LVEF when both are compared to the gold standard of cardiac MRI. This has the potential to revolutionize how doctors and patients can screen for and monitor heart disease both in the U.S. and the developing world," said Caltech’s Mory Gharib, senior author of the paper on the research published in the Journal of Critical Care Medicine.
Gharib and his team are exploring what other information about the heart can be captured by the app -- he anticipates that the technique could be used to diagnose heart valve diseases and coronary artery blockages. Some of the study’s co-authors have also founded a start-up named Avicena that has licensed this technology, and will market the app.