Substernal Epicadial Echo Imaging Technology

byTony Furnary, M.D.
Portland, Oregon

December 9, 2001

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Substernal Epicardial Echocardiography Imaging Technologiy is a new modality for performing postoperative ECHO through a disposable mediastinal imaging device (called SEE IT (SEE imaging technology)) that also functions as a mediastinal drain. The postoperative images are spectacular -- as good as or better than TEE. It can be performed on awake, extubated patients using current TEE ECHO probes passed through the SEE IT device. In my opinion (based by our initial studies of the technique for direct postoperative LV imaging), this technique may rapidly become the gold standard for ruling out tamponade as well as assessing LV / RV and valvular function postoperatively. For a full report of our initial trials, see Ann Thorac Surg 72:S1077-82, Sept 2001.

I have tried to summarize my thoughts on the best methods for insertion of the SEE IT device which has allowed me to obtain optimal images and maintain device position throughout postoperative recovery. I have learned these methods by trial and error, and are sharing these with the HSF readership in hopes that others can quickly maximize their results with this new technology.

1. The main goal of placement of the SEE IT is to keep the tube on a straight course through the skin and rectus muscle, over the apex of the heart, across the anterior RV near the septum, across the RVOT and over the main PA. This pathway allows for continuous contact of the ECHO sleeve with the tissues of the heart.
2. Start by "T-ing" the inferior edge of the pericardium all the way over to the apex. This is where you want the tube to enter the pericardium.
3. With the middle finger of your left hand start at the apex portion of the "T"ed pericardium and bluntly dissect a tunnel anterior to the diaphragm but posterior to the rectus sheath. This tunnel should run inferior as far as you finger can go. It should be aligned (on a left - right plane ) so as to make a straight line with the apex and main PA.
4. Your skin incision should be placed inferior to your finger in this tunnel by an inch or so (further down in an obese patient).
5. Make an oblique incision (45 degrees) with the lateral edge more superior. This helps maintain the constant contact of the flat sock onto the septal area of the RV. Horizontal incisions tend to allow the echo sock to rotate to the right and loose contact with the RV.
6. For an adult TEE probe SEE IT (Model #19716) the incision should be 3 cm long. For the smaller version (Model #19711) the incision should be 2 to 2.5 cm long
7. Place a horizontal mattress suture through the skin edges with the penetration points 1/3 of the way in from each side of the incision. Do not tie this suture down, rather, tie a knot at the very ends of the suture to keep it from slipping out. This suture will be used to close the skin after the SEE IT is removed.
8. Do not wrap the suture around the SEE IT . it will impede passage of the TEE Probe.
9. Since you want to avoid any lateral or anterior /posterior curves on placement of the SEE IT, plan for a straight line insertion from the incision to the apex of the heart. This allows for easier passage of the TEE probe post-op.
10. Take a Tonsil clamp (Lauer clamp) and insert it through the incision on a straight line towards the apex of the heart. It should go through the anterior rectus facia inferior to where it goes through the posterior rectus facia and enter the tunnel somewhere near the middle of your finger.
11. Avoid "diving down" straight through the rectus facia as this will create a sigmoid bend in the tube that will make the probe harder to pass.
12. Open the tonsil clamp wide and dilate all around (180 degrees) to fully dilate the tract. Then pass the tonsil clamp all the way in to the ratchet and pull it back out.
13. Then take a large Kelly clamp and repeat this maneuver dilating the tract even further. I take both my hands and open the Kelly clamp wide to do this dilation. Again rotate the open clamp 180 degrees.
14. At this point your finger should easily fit through the dilated rectus tract. Do not worry about herniation as the anterior and posterior facial defects are not juxtaposed and the rectus muscle will close over the tract upon SEE IT removal.
15. Wet the SEE IT with saline to activate the hydrophilic coating on the outside of the tube. this will make it very slippery.
16. Grab the proximal end of the tube and pull it through the incision.
17. Align the distal tip of the SEE IT over the distal main PA.
18. Place a 6-0 or 5-0 prolene through the tip of the chest tube component of the SEE IT and attach it to the pericardium which overlies the distal main PA where you want the SEE IT to lie. This will prevent the SEE IT from migrating medially over the aorta. There is a potential space between the aorta and the fat of the RV which holds air immediately post-op . If the SEE IT lies over this potential space the ECHO windows in this region will be poor early on. I usually try to use 6-0 prolene (preferred) as it does break easily on removal. the patient dos not feel it at all. The SEE IT actually comes out quite easily as well because of the intraoperative dilatation of the tract and because the hydrophilic coating makes the tube so slippery.
19. Take the inferior "T"ed edge of the pericardium and bring it anterior to the SEE IT. Reattach the inferior edges of the left and right sides to the diaphragmatic pericardium. if this seems to be too tight my second choice would be to just reapproximate the left side of the pericardium to the inferior surface, again over top of the SEE IT. If that is too tight try left sided pericardial fat. This holds the SEE IT down against the apex of the heart insuring full contact of the echo sock onto the heart all the way between the apex and the PA.
20. Finally sew the suture tabs onto the skin as they lie with simple sutures.

When performing the postoperative exam:

1. The HP adult Omniplane 2 probe is a great probe to use. It is 11mm in diameter and will easily pass. Do not try to use the older (1980'sversions) of TEE probes. These are 16 mm in diameter and, although they will fit through the tube , they will cause the patient much pain on passage.
2. The brand new pediatric multiplane form Phillips (HP) is phenomenal. Patients do not even feel this one going in. The images are spectacular.
3. I usually give 2-4 mg of MSO4 before doing an exam. Patients usually experience a pressure-pain sensation as the probe head passes through the rectus. This abates after the probe head is through the rectus and into the pericardial space.
4. On a scale of 1-10 the adult probes usually elicit a 2 to 5 response as to the level of pressure pain. The pediatric probes are a 0 or 1.
5. If the images seem to become muddled in the middle of the exam , try infusing more water through the port. Often a vacuum is created as the probe is pushed in and pulled out many times during the exam. This may push out the saline (or water) and suck some air into the sock thus degrading the image.
6. If you see an air leak in the pleuravac this is most likely coming from air sucked in along the ridges of the SEE IT. I usually take the tube off of suction to see if it is a real (alveolar) leak. Otherwise I don't worry about it.