Transcription
Hi everyone, my name is Onyachi Ak, and I'm an ultrasound fellow. Here with me is the chief of our division, Dr. Litepla.
Hi everybody, thanks for joining today. We'll be talking about pericardial tamponade. Let's get into it.
So we're going to start with a case. This was a gentleman who came in with the chief complaint: "I can't breathe." He was a 65-year-old male with a history of ESRD and CAD, presenting with three days of progressive chest pain and shortness of breath. He was actually at dialysis and could not complete his session because he felt so out of breath.
On presentation, he was hypotensive. We placed a probe on his chest, and this is what we found. Andrew, what do you see?
I see a beautiful parasternal long axis view with what looks like a significant pericardial effusion.
That goes to our talk. So today, again, we'll be talking about pericardial tamponade. Tamponade occurs when fluid in the pericardial sac compresses the heart and decreases cardiac output. It is a diagnosis that is made by echo, and the management is based on the clinical findings as well as on the echo findings.
The management includes IV fluids and pericardiocentesis. You might wonder how good our physical exam and history are in diagnosing cardiac tamponade. Well, this was a meta-analysis looking at history and physical exam findings of patients who were diagnosed with tamponade. As we can see, the sensitivities are variable, and even the best sensitivities are only about 80 percent.
I find that this is very interesting because every time we call cardiology or some other consultation about a suspected tamponade, they ask, "Well, what's the pulses?" Knowing that the normal pulses do not rule it out, I think is really useful.
Thanks, Andrew. So today, we'll be talking about the echo findings of tamponade. These include the presence of pericardial effusion, systolic right atrial collapse, diastolic right ventricular collapse, IVC plethora, and exaggerated respiratory cycle changes in mitral inflow velocity, or a surrogate for pulses paradoxes.
So let's start with pericardial effusion. In these figures or videos, we see pericardial effusion in the parasternal long axis, parasternal short axis, subxiphoid, and apical four-chamber views. The pericardial sac has less than 30 cc of IV fluid, so any additional fluid can cause hemodynamic compromise.
So how do you think about sizing pericardial effusions? I think for tamponade physiology, size is not as important as the rate of accumulation of fluid and the ability for the pericardial sac to accommodate the fluid. For example, in patients with chronic conditions like malignancy or ESRD, they could have a larger effusion but have no hemodynamic compromise.
However, in patients with acute conditions, even with small effusions, there might be hemodynamic collapse. The next finding is systolic right atrial collapse. Now, this is an early echo sign of tamponade.
And why is that? This is because the right atrium is under lower pressure compared to the right ventricle; therefore, it's more susceptible to compression from fluid in the pericardial sac. The best views to obtain this are the parasternal long axis and an apical chamber, as indicated by the blue arrows.
Now, the sensitivities and specificities are very broad. So again, a takeaway from this slide is that this is an echo sign of tamponade that can be seen early on. The next finding is diastolic right ventricular collapse.
When we look at the upper left figure, we see a heart in which the right ventricular free wall is scalloping. A good way to think about that is you're changing concavity. If you guys remember back to high school calculus, we talked about the concavity of lines. When it's bowing downward, then it's concave inward.
Our friend Dr. Chris Fox has described this as a tiny little person jumping on a trampoline. The way to examine if this right ventricular collapse is occurring in diastole is to use M-mode.
When we use M-mode, it goes over the right ventricular free wall and cuts across the mitral valve. This is the figure that we see. The first thing here is the pericardial fluid, then we have the right ventricular free wall, right ventricle, septum, left ventricle, and then the mitral valves.
When the mitral valve opens, that is diastole, and then when we correlate that with right ventricular collapse, that is tamponade physiology. I would just say that that's a beautiful picture, but you don't have to have M-mode for the advanced practitioner who's great at ultrasound.
This is beautiful when you can get it, but usually the 2D mode is enough. Thanks, Andrew. This finding, while not very sensitive, is pretty specific.
The next finding is IVC plethora. The reason we have plethora of the IVC is that the fluid in the pericardial sac is compressing the right chamber of the heart, so fluid backs up into the IVC.
Now, this is a qualitative analysis where we look and say, "Is it plump or is it not?" However, if you want to have a quantitative analysis, the way to do so is to measure the IVC two to three centimeters from the atrial cable junction, right where the hepatic veins empty into the IVC.
If it's more than two centimeters with less than fifty percent inspiratory reduction, that is concerning for tamponade physiology. While this is a very sensitive test, it doesn't have a high specificity.
Okay, so let's see what that means. A very high sensitivity test means that almost everybody with tamponade has IVC plethora. Therefore, if the IVC is small and collapsing, it's most likely not tamponade.
Our last echo finding is exaggerated respiratory cycle changes in mitral inflow velocities, again a surrogate for pulses paradoxes. Flow in and out of the heart varies with respiration. In tamponade physiology, the variation is exaggerated.
So how do you do it? First of all, you obtain your image in the apical four-chamber view, and then using pulse wave Doppler, you place the gates just distal to the opening of the mitral valve and look at flow over time. Normal variation of flow is less than 25 percent. If it's more than that, that is concerning for tamponade physiology.
The sensitivity again is about 82 percent. So when we go back to our case with this gentleman with ESRD, CAD, and hypotension with these findings, Andrew, what do you think?
Well, I can see a little bit of maybe right atrial collapse there. So with echocardiographic signs of tamponade and the hypotension, I think you need to act quickly. We don't know exactly how long he's had this, but the first thing is I would give him some IV fluids.
The game is to maximize the pressure inside the right ventricle to combat the pressure from outside around the heart. Then we would either prepare for pericardiocentesis at the bedside or call cardiology to do it, depending on what your local practices are.
In summary, pericardial tamponade: the clinical exam and the history are not very sensitive. There's no finding on history or exam that can rule it in or out. Clinically, echo is the gold standard for diagnosis.
That's right. So echo can rule out or identify tamponade. It's also very helpful when you see absolutely no effusion; then you know it's not tamponade.
But this is where the clinical picture is really important. People talk about it being a clinical diagnosis. Well, it's more than that; it's a joint echo and clinical diagnosis.
As far as the diagnosis and management, the echo signs include the presence of a pericardial effusion, atrial systolic collapse, which is an early finding, right ventricular diastolic collapse, which is the most specific finding, IVC plethora, which is the most sensitive finding, and exaggerated changes in mitral valve inflow velocity, which is a surrogate again for pulses paradoxes.
Thank you to all the listeners. Thank you, Andrew. Thank you so much. Thanks, Onyachi, and we hope you find this information helpful. Follow us on Twitter. Bye, guys!