Redbud Medical Systems, Inc.
Custom-made beds for Supine bike stress
echo, Post treadmill imaging exercise echo, & Resting echo
Models:
400
500
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The following is excerpted, with permission, from the Manual for Stress Echo by Larry DeBord. This was written several years ago when the only digital acquisition systems (frame grabbers) were stand-alone computers. Some of the comments and suggestions apply specifically to one of these systems, the Tom-Tec (Freeland). While the concepts and basic protocol as described are fundamentally useful, you may find that your integrated frame grabber's software may not be flexible enough to perform some of these actions.
Chapter 13
Formatting the Stress Echo Study
Our next job is to review the digital images we have captured, select those that are diagnostically useful and to format them in a way that facilitates accurate judgement about myocardial contractility as affected by the exercise. The "standard" treadmill protocol calls for one immediate post-exercise image of the PSLA, PSSA, AP-4 & Ap-2. These are juxtaposed with their respective resting loops as seen below.
Four REST and four IMPOST loops
formatted in the "Standard Protocol."(above)
I feel that this limited number of images can lead to error. In our supine bike exams I examine each of the captured loops, and save many if not all the diagnostically useful ones, and then arrange these many digital loops in way that is most useful for the doctor to read.
On each quad-screen page I place one REST in the upper left (see illustration below). Because those images acquired during PEAK are the most important, I include two for each page. In the lower right corner I place an IMPOST loop. Minimally I assemble such a page for each of the five views. But usually I construct at least two such pages for each view - as many as are useful to illuminate ambiguous wall motion. Generally, the poorer the images, the more I keep for the reading. A very difficult study with poor definition or contradictory loops may include 10 - 15 quad screen pages. The doctor should see the ambiguity and the degree of uncertainty in the images rather than a shortened version censored by the echocardiographer.
Formatting in the Preferred Preferred Protocol includes the
loops of five planes; 1 REST, 2 PEAKs & 1 IMPOST. These 20 loops are the minimum
presented for reading, but usually twice this many are included to increase
confidence and/or to demonstrate ambiguity. Compare the information presented
here with that in the "Standard Protocol" above.
Preferred Formatting
1. Assemble each quad-screen page to have 1 REST, 2PEAKs, 1 IMPOST of each of the five views. (Make sure each is in a similar orthographic plane and is triggered correctly.)
2. Assemble multiple pages of each view as necessary to reveal ambiguity or to increase confidence.
3. If there is a previous study on this patient, retrieve it now for comparison with the present study. The frame grabber allows you to present useful alternate formats such as pre- and post angioplasty views of the same cut to demonstrate improved contractility.
[Freeland users: After all the useful PEAK and IMPOST loops have been locked into preferred loops, we could at this point clear (Shift F5) all the unlocked , non-diagnostic loops from RAM, leaving the remaining selected loops scattered throughout the primary loops from A through AG. This scattered spread makes it unwieldy to re-assemble the loops to the final format of REST, PEAK, PEAK, IMPOST on every page, so I do the following:
Save (F10) these locked loops to the hard disk. When these PEAK and IMPOST loops are now retrieved, along with the previously saved REST, they all appear adjacent and "consecutively compacted" in the first few primary pages of RAM.
Note, however, they are not in the final format we want. At the beginning are all the views of REST which are followed by all the PEAKs and then the IMPOSTs. So Unlock (<Shift F9>) all the loops. They can now easily be selected and locked, one at a time, to fit our format style. The loops must be locked in the proper sequence in the order they are to appear in the final format. See Figure 133..]
Reading the Study
In our lab, the study is read immediately after the study; not at the end of the day. The images are still fresh in the sonographers and doctors minds. The video tape is already loaded and the digital study is playing. All the extra loops of multiple images of each cut are now available for reading. And the patient receives his diagnosis before leaving. However, there is one benefit to reading the studies at the end of day: it may be possible to assemble everyone in the group to review together, to share ideas about what the walls are doing. Without this exchange initially, readers develop bad reading habits and fail to learn as quickly as they could. Without such group readings, there is a debilitating lack of consensus, and the diagnosis of the studies may depend less upon how the heart acted and more upon who read the images. (Reading is covered in detail in Chapter 14.)
If the technologist is not invited to participate in the reading and if he is not charged with the responsibility of obtaining the data and reading the data, he will not be motivated to get the information. Instead, he will be merely "scanning." Merely getting the Ap-4 is not sufficient. He must be able to answer the question, is the lateral wall improving or remaining the same?
Archiving the Study
When the final format for the exam is completed, we may have up to 50 loops to confirm a diagnosis. Not just eight. These extra loops allow consideration of ambiguity and they increase reader confidence that what he sees represents what actually happened. All these loops are usually more than is necessary for archival, so only the best ones, the most representative ones, those that best support the diagnosis, are archived to disk. If the study must be read later, the entire collection should be saved temporarily on the hard disk.
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Content revised: January 24, 2004