Assessment of Perioperative Events and Problems

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Assessment of Perioperative Events and Problems

Ricardo Martinez-Ruiz and Christopher J. Gallagher

Hypotension and Causes of Cardiovascular Instability

Real World Note

Let’s face it, cowboys and cowgirls, this is the real crux of the whole deal with echo. All the cool physics and gradients and Doppler stuff are necessary for the test. And if you’re going to do cardiac echo, you need to know all the neato-frito valve details. But as TEE gets more and more common, the day will come when every single anesthesiologist or ICUologist will need to know at least the basics of TEE to figure out what’s going on when a patient gets unstable.

The TEE is the anticrash weapon of choice.

When badness happens (and we’ve all seen it happen), you might not have a Swan or CVP. And even if you do, you’re still wrestling with numbers that tell you something, but not the whole picture. You are left with a set of numbers from which you infer, or hope, you have the picture.

The TEE gives you the real picture, right now, no need for a leap of faith.

Cahalan points out in the tapes and at the meetings that, even with only a little TEE experience, most people can diagnose the most common problems in mere minutes. After all, when most patients go to caca, you want to know:

For most problems, then, Cahalan gives us a nice, neat, easy-to-understand and inherently obvious breakdown of the main causes of hypotension:

1. End-diastolic area decreased, ventricle contracting OK—You’re low on volume. The heart is empty, so fill it.

2. End-diastolic area increased, ventricle contracting poorly—You have a bad and already overfilled ventricle. Fix whatever’s causing the global hypokinesis (Get a blood gas! Don’t forget the basic stuff!), and once you’ve fixed what you can fix, it’s time for inotropes or ventricular support of some kind.

3. End-diastolic volume normal or low, ventricle contracting well or hyperdynamic—You have a problem with the volume not “going where it’s supposed to go”. Either the volume is all going out into a vastly dilated circulatory tree (anaphylaxis with low systemic vascular resistance), or else some other channel is misrouting your good cardiac output (severe mitral regurg or aortic regurg, or a ventricular septal defect).

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The first two are easy to see with a glance at the TEE. The third is a little trickier, but you can augment your TEE findings with other stuff. (Flushed appearance and wheezing going along with anaphylaxis; murmurs or further TEE views to find mitral regurg, aortic regurg, or a VSD.)

Then the final thing you want to know, “Tamponade, yes or no?”, is figure-outable with your basic search for a pericardial effusion plus the hemodynamics of tamponade.

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If you take nothing else away from TEE (say you don’t want to bother taking the TEE exam), if you at least know this, the differential for hypotension, you will save somebody some day.

Cardiac Surgery: Techniques and Problems

Assessment of Bypass and Cardioplegia

How the hell do you use TEE to assess bypass and cardioplegia? Got me. I have no clue what the Society of Cardiovascular Anesthesia folk were thinking when they put this on their magical list.

Let’s stretch a little and try to figure this one out.

One thing is worth mentioning at this time. Disconnect your echo probe while on bypass. That will allow the probe to cool down and prevent esophageal burns. And remember that you do need to disconnect the probe, not just put the image on FREEZE. Although the word FREEZE implies a cool state of affairs, you have just frozen the image. You haven’t actually frozen the probe and turned it into a big Fudgecicle.

Cannulas and Devices Commonly Used During Cardiac Surgery

The main cannula you’ll be asked to visualize is the retrograde cannula for cardioplegia. First, you need to know where the coronary sinus is (the site of the retrograde cannula).

To see the coronary sinus on TEE, you need to get your ME 4-chamber view and slowly advance the probe into the stomach and VOILA!!! The coronary sinus shows up as a drak conduit that drains into the right atrium (you can check with Doppler to see the coronary sinus blood flow). Ocassionally you may have a valve (Thebesian valve) impeding the easy positioning of the retrograde cannula, the cannula gets stuck on it. It is pretty cool to tell your surgeon that the reason he is struggling getting it in position is because of the valve.

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Cannula to cross the threshold. Like all cannulas, the retrograde cannula has a “double line” that tells you it’s a man-made thingamajig. And like all cannulas, its 3-D reality will dive in and out of your 2-D picture, making it sometimes a little tough to keep it entirely in view. In some occasions you may see the stippled balloon at the end of the cannula: it looks like a star cluster (yes…use your imagination!).

Circulatory Assist Devices

It’s not a stretch to look for correct placement of an intra-aortic balloon pump. You want to see the tip of the IABP at the takeoff to the left subclavian artery. No higher (occlusion to the left arm) and no lower (inadequate function of the balloon pump and potential occlusion of renal arteries, oops). You should see the tip of the IABP, but no balloon!, at the level of the takeoff of the Lt subclavian artery on the most upper view of the descending thoracic aorta. As soon as you push the probe deeper, the balloon should be visible with its characteristic up and down, up and down… (you can also assess the quality of expansion of the balloon).

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Things can get more exotic, of course.

Left and right ventricular assist devices, and ECMO when things are going really swell, all enter the cardiac realm in this Brave New World we inhabit.

With an LVAD, you want to make sure the person doesn’t have a patent foramen ovale or interatrial septal defect. You could, as the blood rushes out of the left side into the assist device, “suck” blood from the right side over to the left.

If this happens, then no blood goes out the right side, so no blood goes to the lungs, so no oxygen enters the body. Unless your patient is a cyanobacterium, he or she will need oxygen.

So check for these PFO when you start an LVAD. You may also need to make sure that there is no aortic regurgitation. If that happens blood will “recirculate” in a circle of death >>>> from the LV >>> to LVAD >>>> to aorta >>> back to LV.

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Once the LVAD is going, you can also use the TEE to confirm that the aortic valve isn’t opening. At first that concept seems a little jarring.

Yes, usually that is the case, but remember, you’re not in Kansas anymore, Dorothy. The LVAD is doing all the work now. You want all the blood to leave the heart and go into the machine.

In testville, remember that the cannula that is draining blood out of the body into the machine is the inflow cannula. (That is, inflow as far as the machine is concerned. You could get faked out and think, well, relative to the body, that is technically outflow, so… Don’t think that!)

There are two new gadgets for LV support that can be placed percutaneously >> the Tandem heart and the Impella. The Tandem inflow cannula goes from the femoral vein into the IVC into the RA and then goes through the interatrial septum into the LA! The LA blood is pulled into the centrifugal pump located outside the body to be reinfused into the arterial system via the femoral artery to provide systemic perfusion. You can check the placement of the inflow cannula as it goes across the interatrial septum.

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The impella is different: it consists of a very small impeller-based pump that its placed across the aortic valve (via the femoral artery most commonly) and sucks blood out of the LV and propels it back into the aorta. This will provide for overall systemic perfusion needs and will also let the LV decompress and recover. Neat stuff!!!

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ECMO and RVADs? You can use TEE to check those cannulas too and just make sure they seem to be in the right place.

Off-pump Cardiac Surgery

Now this is more like it.

As a sign of the times, I looked back at the tapes for the 1999 TEE course. People then were talking about doing off-pump cardiac surgery in “select cases” and doing relatively small percentages of people off pump. Well, of course, by now, everybody and their second cousin is doing off-pump CABGs. McDonald’s will have a drive-thru window soon where you can get off-pump CABG done.

One pain in the ass, actually THE pain in the ass, with off pumps is “the hike”—when the surgeons lift the heart to get at those dim and distant distals. Hemodynamically the patient’s blood pressure often takes a hit with the hike, though the newer “holder thingies” and more surgeon experience have made the whole process less devastating than in days of yore. The hike also goofs up the echo, because now you may have air between the heart and the probe.

No can do the transgastric view, no way.

Hike the heart, the view goes away.

The whole deal during off-pump surgery is, “Can we do this off pump?” or “Are things getting SO BAD that we have to stop this charade, put in cannulas, and do this on pump?”. Pertinent to us is the question, “Can the TEE help me make that decision?”.

What tells you things are going to the dogs?

But during off-pump cases, you are actually looking at the wall right there, with your own eyeballs. Even “hard to see” walls are hiked up for you and the surgeon and everyone to see. You can, of course, confirm it with the TEE, but your eyeballs do just as well in the OR.

TEE helps you to see the mitral and tricuspid regurg, of course. (Unless you’re Superman, most of us can’t see inside the heart.)

So how much and how long of a wall motion abnormality is enough to push you “onto the pump”?

Uh…

Jack Shanewise gives this talk at the TEE conference. (He’s a great speaker, so don’t miss him. Remember, he spearheaded the big paper that gave us the “big 20” views, so he knows from TEE.) He tells us he usually sees signs of ischemia or wall motion abnormalities during these off-pump cases, but that as long as things improve after the anastomosis is complete, you’re usually (not always) OK.

Having heard the talk and done a bunch of off-pump cases, you’re still left with a bit of a “by guess and by God” feeling about these off-pump cases:

How’s that for the state of the art?

I tell residents an off-pump case is like a labor epidural that’s just kind of, sort of working. You pray and pray for the lady to deliver so that you’ll just be done with it! Same with these cases: you pray and pray that they get the grafts done so you’ll just be done with it!

Coronary Surgery: Techniques and Assessment

How will TEE help you in an on-pump CABG? (Since we talked about off-pump just a second ago.)

Pretty much, the TEE will replace the Swan. (This debate will swirl around for a long time, particularly the “What happens when the patient goes to the ICU; do we put a probe in again each time we get in trouble? You guys have it in the whole time in the OR, but we in the ICU don’t!”.)

With the TEE going in nearly all our patients (people at the meeting confirmed that, in a lot of places, heart surgery means a TEE, period), you get most of your “Swan-like” information right there from the TEE. (We do put introducers in everybody, so we can always put a Swan in later.)

In effect, this discussion is the exact same discussion as in Hypotension and Causes of Cardiovascular Instability above. What, after all, are you concerned about during a CABG? Hypotension and cardiovascular instability. So, boom, same exact analysis.

This helps you out at all points of the case. Hypotension and cardiovascular instability can and do happen whenever they want to—at induction, during the IMA dissection, coming off pump, whenever.

TEE also helps in regional wall motion abnormality analysis. This goes right back to another previous discussion in Chapter 14 (see Coronary Artery Distribution and Flow).

Examine the patient ahead of time, look for wall motion abnormalities. See which grafts go in which distribution. If you see a new wall motion abnormality, that is evidence a graft is not working.

This comes in especially handy once the chest is closed. The skin and sternum are “in the way” and the TEE helps you see what your eyes no longer can.

Valve Surgery: Techniques and Assessment

Valve Replacement: Mechanical, Bioprosthetic, and Other

Not to sound like a broken record here, but TEE helps you during valve surgery the same way it helps you during CABGs, that is, in the evaluation of cardiac function and volumes, the management of hypotension and cardiovascular instability.

TEE helps you keep the blood going round in circles in your patient, and Oh be Joyful to that. How?

Do we see a pattern here?

But in valve surgery, we go a little further than management of hypotension and cardiovascular instability. We look at the valve itself, before surgery, to confirm the diagnosis and assess severity, and after surgery, to confirm good function of the valve and make sure there aren’t any problems. And yes, once all is done, we go back like dutiful soldiers to evaluating for hypotension and cardiovascular instability.

Test Note

You’ve got a little memorizing to do. You will need to know what different valves look like on echo. Not the end of the world, but the hyphenated double names of the artificial valves drove me cuckoo. Doesn’t any one person ever design a valve?

Let’s plow through the various kinds of valves and how they look. Different ones have different jets of regurg (you’ll need to know that too), but one thing holds true for all valve replacements. You should not see a PERI-valvular leak. You shouldn’t see leaking OUTSIDE the sewing ring. That means bad news. All valves have some leaking INSIDE the sewing ring, but not, repeat not, outside.

Another goody to know: prosthetic valves all need anticoagulation, tissue valves don’t. Now, on to the specific valves.

Note

get all the valve pics and make them smaller and put them together in one pic.

Ross Procedure

Take out the diseased aortic valve, take out the native pulmonic valve, put the pulmonic valve in the aortic place, put a tissue graft in place of the pulmonic valve.

Test Note

For me, the shadows from the tissue valve stents and the shadows from the prosthetic valves can look pretty similar. Watch the video of this or study the CD movies of these a lot because, on the test, you only have a minute or so to look at these, and it can be pretty confusing. If there is one area where you can get fooled, this is it.

There are stentless prosthetic valves. You won’t see the metal and their reflections, but you may see a sewing ring. That is an extremely subtle finding and easy to miss.

An issue with tissue valves is longevity. They tend to wear out faster.

You can measure gradients across these valves, but it can be challenging. You have to know where the tight spots are and you have to navigate a straight shot through that spot. For example, for a Starr-Edwards, you’ll have to slip your Doppler right through one of those regurgitant jets around the sides of the ball.

A useful “Internal Medicine-y” thing to know about gradients: when you are evaluating a valve and see a gradient you think is a little high, remember, all valves have some gradient. Try to find an old reading of the gradient before you ring the alarm bells. The thinking is the same as getting an old ECG or CXR for comparison.

All valves are subject to embolism and endocarditis. So you’ll be looking through some confusing reflections (try different angles to avoid the metallic shadow) as you hunt for fistulas, abscesses, and clots.

Valve Repair

Transplantation Surgery

Lung

Most lungs are, you sincerely hope, full of air, so it’s a toughie to examine them with TEE. Unless the lung is consolidated you might be able to “see” the parenchyma > bad thing. Also with big pleural effusions you can see the lung “floating” in the descending thoracic aortic views. You can also see the presence of clot and fibrin in the fluid (pretty cool).

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So in those rare cases of lung transplants (not done too often or in too many places), you’re left with doing the usual stuff—monitoring the heart for signs of failure.

You will yawn when I say this, but you’ll be looking to monitor for hypotension and cardiovascular instability; that is, you’ll watch for:

What more can I say—by now we keep coming back to the main things a TEE does!

The TEE, your friend indeed in time of need.

Questions

1. When placing an LVAD you should look for, except:

2. The inflow cannula for the Tandem Heart is located in:

3. The mitral regurgitant jet of a bioprosthesis is, except:

4. In the case of an anaphylactic shock the heart is/has:

5. In order to assess for contractility in an off pump CABG, you should, except:

Answers

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