Researchers at the Tripler Army Medical Center in Honolulu are turning to real-time tele-echocardiology interpretation to overcome the distance between cardiologists and far-flung patient populations.
Routine store-and-forward systems like the telecardiology link between Tripler and the image acquisition center at the U.S. Naval Hospital on the island of Guam have inherent delays, restricting management of acute medical conditions.
The real-time tele-echocardiography interpretation methodology used by investigators at Tripler involves a unique application of the eICU, a product from Baltimore-based VISICU, that is described in the October 2004 issue of the Hawaii Medical Journal.
The eICU transmits high volumes of video, audio, and primary physiologic monitoring data over T1 lines at rates of up to 1544 kb/sec.
"The connection between Tripler and Guam covers 3800 miles, the greatest distance reported using this technology," said Dr. Jamalah A. Munir, CPT, of Tripler's medicine department.
In February 2004, a 55-year old man with a history of prior myocardial infarction presented with recurrent chest pain at the Guam hospital. Physicians performed an echocardiogram and trained a video camera (768 x 492 resolution on the echo screen. The data were transmitted simultaneously to Tripler for real-time interpretation by a cardiologist, facilitating medical management.
Until then, echocardiogram file transfers (90 to 120 MB each) had occurred only during off-duty hours, when reduced network traffic could increase the efficiency of the synchronous transmission and decrease the loss of potentially vital information.
"Given these constraints, there was approximately a 24-hour lag time for interpretation," Munir said.
She acknowledges that the new approach faces limitations.
The capture rate of the camera (32 frames/sec) is less than the current frame rate used in the traditional store-and-forward setup. And the gain required to make the image interpretable for live interpretation is significantly higher than the usual settings.
"In this case, there was no appreciable difference in the interpretation of the live versus store-and-forward echocardiogram," she said. "However, a subtle wall motion abnormality may have been missed at this frame rate."
Nevertheless, Munir sees plenty of potential applications for telecardiology. Patients with known or suspected heart disease are frequently cared for in remote intensive care units, emergency rooms, and newborn nurseries, without immediate availability of cardiologists.
"Essential information can be obtained via tele-echocardiography, including determination of congenital heart disease in neonates, pericardial effusions, severe valvular disease, wall motion abnormalities, and overall cardiac function," she said.