Echocardiography has been the most widely-used diagnostic test for heart disease for more than 50 years for good reason. It’s portable, safe and technological advancements keep the modality at the forefront of screening and diagnosing heart disease. Looking ahead, cardiologists are eyeing 4D cardiac imaging and ever-smaller equipment.
Several studies presented at the annual meeting of the American Society of Echocardiography (ASE) in June reinforced the understanding of ultrasound as an important tool in combating various forms of heart disease.
A study conducted at the University of Nebraska Medical Center found that real-time perfusion echocardiography is helpful in identifying diabetics without symptoms who are at risk for coronary artery disease. Another study showed that stress echocardiography is a more accurate method for identifying women at highest risk for coronary artery disease (CAD) than traditional stress testing and clinical risk factors.
In September, the Journal of the American Society of Echocardiography released new recommendations to further support the role of stress echocardiography in accurately identifying coronary artery disease and in determining prognosis of patients with known or suspected coronary artery disease.
Regular echocardiography in the resting state is equally beneficial to men and women, but this kind of echo stress testing is particularly beneficial to women. Since the heart lies below the left breast, other types of stress tests, especially nuclear, can be difficult to interpret because breast tissue is in the way, says Vera Rigolin, MD, a cardiologist at Northwestern Memorial Hospital in Chicago. The facility uses Vivid echocardiography systems from GE Healthcare. Plus, radiation used to image the heart also exposes breast tissue. Since echo doesn’t use radiation, there is no exposure risk.
That safety translates well to patients with severe valve issues who require an echo at least once a year to track their condition.
Benefits of real-time imaging
Aside from the benefits of portability and no radiation, echocardiography offers real-time imaging. “With all other modalities, you acquire images and look at them later,” says Rigolin. During echocardiography, sonographers are actually seeing and controlling the images they acquire. If they see an abnormality, they can change focus and really hone in, she says. That’s not possible with other modalities.
Echocardiography has been around for a long time, but continues to make incredible advances in imaging, Rigolin says. It provides “an incredible amount of useful and important information about the structure of the heart.” 2D images give clinicians an idea of how the heart is squeezing, how valves are opening, and whether there are clots, fluid or masses on valves. Doppler imaging gives information about the direction of blood flow, whether there are leaky valves or valves not opening properly, and abnormal blood flow.
3D echocardiography does 2D imaging one better. While 2D echo images one slice of the heart at a time, 3D echo images the entire heart all at the same time. “That gives us a much more realistic and accurate assessment,” she says.
Tissue Doppler is another essential technique that utilizes Doppler to look at the heart muscle rather than the heart chambers and valves. “That gives us an idea of how well the muscle is contracting and relaxing and the timing with respect to how well one wall is contracting in respect to another wall,” Rigolin says. This becomes very important in heart failure patients, with tissue Doppler key in evaluating those patients for certain types of pacemaker devices.
Paula Carr, technical director of the echo lab at the Iowa Heart Center, also appreciates tissue Doppler. “Most of our studies are scanned in harmonic frequency. We hardly ever use fundamental frequency anymore.” Tissue strain imaging (TSI) is used in parts of research. TSI permits a dynamic observation of walls in the lower extremity arteries. With TSI, it is possible to detect a significant reduction in the strain value in lower extremity arteries at risk of developing arteriosclerosis.
TEE avoids interference
Rigolin also cites advances in transesophageal echocardiography (TEE) making a difference in patient care. The patient swallows an ultrasound transducer that is positioned next to the esophagus, which sits directly behind the heart. With