Dextrocardia

NEW ORLEANS -- A new generation of portable hand-held ultrasound imagers no bigger than a laptop shows great promise for point-of-care fetal echocardiographic screening, Dr. Margarete Olivier said at the annual scientific sessions of the American Heart Association.

"We envision that [such a device] can be a very useful tool, much like an optical stethoscope, in a situation where one wants to have a quick and focused glance at the fetus and fetal heart," said Dr. Olivier of the Mayo Clinic, Rochester, Minn.

The new point-of-care devices may, in many instances, enable physicians to avoid utilization of conventional echocardiographic equipment for obstetric screening for congenital heart disease. In addition to being far more expensive, standard echocardiographic gear is cumbersome and ill-suited to rapid deployment in pregnant patients in diverse settings such as the antenatal unit, emergency room, and ICU.

The first of these new highly portable devices to have reached the market is the SonoHeart. Its manufacturer, SonoSite Inc., refers to it as a "PUI," for personal ultrasound imager.

Meanwhile, Agilent Technologies Inc. is gearing up to market its first device, which it calls a Small Portable Ultrasound Device, or "SPUD."

SPUDs and PUIs weigh only 5-7 pounds. They consist of a 2.5-MHz transducer, battery and base unit with a small display screen. Compromises made to achieve superportability include a limited number of simplified controls for adjusting imaging depth and gain, an imaging capability limited to 2-D and color Doppler, and inability to store images for later use.

To study the utility of SonoSite's PUI in performing screening fetal echocardiography. Dr. Olivier examined 21 consecutive mothers carrying 22 fetuses referred at a median of 23 weeks' gestation for fetal echocardiographic evaluation because of an abnormal obstetric ultrasound finding or a family history of congenital heart disease. All 22 fetuses were evaluated first by PUI, then by standard echocardiography

A fetal echocardiographic screening examination involves visualization of a four-chambered view of the heart with the atrial and ventricular septum and right and left ventricular outflow tracts, as well as measurements of ventricular length, cardiothoracic ratio, and other cardiac dimensions.

The PUI permitted complete visualization of the four-chambered view in 19 of 22 cases, the left ventricular outflow tract in 20, and the right ventricular outflow tract in 21. Standard echocardiography provided adequate images in all 22 cases. Cardiac dimensions as measured using the two devices were similar. Both portable and standard echocardiography identified one case of isolated dextrocardia and one case of cardiac dextroposition.

While the personal ultrasound imager resulted in inadequate cardiac images in 14% of cases, these were readily recognized as such, permitting prompt triage to standard echocardiography, Dr. Olivier said.

In another presentation, Dr. Kirk T. Spencer predicted that as PUIs and SPUDs become even smaller and more powerful, physicians will confront a number of novel issues.

"Who should be trained to use these devices, cardiologists or noncardiologists? What about the duration of training and assessment of competency? Which patients do we study? Will we use the technology routinely like a stethoscope or rather as a directed screening exam? Also important will be issues of reimbursement and documentation," commented Dr. Spencer, who is with the University of Chicago.

COPYRIGHT 2001 International Medical News Group
COPYRIGHT 2001 Gale Group