When it comes to diagnosing certain heart diseases, this older testing modality is a workhorse. It is also now used to guide new treatments.
Most people are familiar with ultrasound as the technology used to monitor unborn babies during pregnancy. When ultrasound is used to look inside a beating heart from outside the body, it is called echocardiography. The technology produces images from sound waves bounced off the heart.
Echocardiography is the most commonly used noninvasive testing modality that allows physicians to view the heart on a screen as it beats. This makes it essential for monitoring how well the valves are working, or how effectively a ventricle is contracting in a patient with heart failure.
“I’m very pro echo. We all love it,” says Christine Jellis, MD, PhD, a Cleveland Clinic cardiologist with specialty expertise in cardiovascular imaging. “It doesn’t emit radiation, it’s relatively cost-effective and it’s portable. We can wheel it to the bedside and get immediate information,” she says.
Patients also like echocardiography because it’s painless, noninvasive and quiet. They can see their heart beating on the screen and watch blood flowing through it.
“We can explain what we are seeing, and what’s going on, in real time while we do the test,” says Dr. Jellis.
Echocardiography is not new, but ongoing improvements in the technology have allowed it to remain one of cardiology’s “go-to” diagnostic modalities. Its newest role is in guiding exciting new therapies.
One of the most common uses of echocardiography is to evaluate the function of the heart’s valves. For this purpose, Doppler imaging is generally used. Doppler measures how sound waves change in speed as they move toward or away from you.
As blood flows away from and toward the ultrasound probe, Doppler produces a telltale “whosh whosh” sound. Blood flowing towards the probe appears blue, and blood flowing away from the probe is red. This information allows the cardiologist to assess the heart’s structure and evaluate whether a valve is restricting blood flow or leaking.
“A resting echo is a good first step, because it gives us valuable information that determines what other studies might need to be done,” says Dr. Jellis.
Cardiac echocardiography is usually performed by placing the probe on the patient’s chest. When clearer images of the heart are required, a different style of probe can be inserted into the esophagus. This technique, called trans-esophageal echocardiography, allows the probe to be positioned right next to the heart to give the cardiologist a better view without interference from the ribs.
Two new techniques called 3D echocardiography and strain echocardiography have improved the ability to detect abnormalities in the heart.
Standard echocardiograms are seen in two dimensions. When a flat image is unable to provide the desired information—for example, the volume of the heart’s chambers—a 3D image can be obtained.
Strain imaging is a novel form of echocardiography that measures how much the heart deforms as it contracts. The computer compares this figure against the shape of the heart in its relaxed state to determine the degree of shape change.
“Strain imaging is so sensitive that it can detect reduced ventricular function before it can be identified by other measures, such as ejection fraction,” says Dr. Jellis.
While strain imaging is finding its place in patient care, cardiologists are excited about its potential. “We hope this technique will allow us to be proactive in identifying and treating different pathologies early, before permanent damage occurs,” she says.
The ability to obtain real-time images without radiation makes echocardiography a natural option for monitoring interventional procedures that require the cardiologist to see inside the heart. For these reasons, echocardiography is used to guide transcatheter aortic valve replacement (TAVR) and the placement of left atrial appendage closure devices to reduce the risk of stroke from atrial fibrillation.
This is likely just the beginning of echocardiography’s future in therapeutics.
“New applications are constantly being developed. Echocardiography remains an exciting field for us to explore,” says Dr. Jellis.