okay I want to welcome everybody to our fourth lesson in this series of lessons on shock and this lesson we're going to be talking about cardiogenic shock My name is Eddie Watson and I will be presenting this series of lessons. And in order to stay up to date on the lessons as we release them, make sure and subscribe to our channel below. And also don't forget to hit that bell icon in order to be notified when we release the new lessons and they become available. And with that said, let's go ahead and jump into our lesson on cardiogenic shock. So in our last lesson, we did a deep dive into hypovolemic shock and what all is going on when you have a patient that's in that type of shock.
And in the previous lessons in this series, we've really broken down and given you a good explanation of what shock is and what's happening with the body. So for this lesson, we're going to be doing a deep dive into our cardiogenic shock. And just like in the last lesson, we're going to break this down into its root words, which we have cardio and genic. And here, cardio means Heart, and genic, is originating from.
And so what this means is in cardiogenic shock, the shock state is originating from a heart issue. Essentially, the heart is not able to beat enough blood in order to produce enough perfusion to meet the body's needs. And so this is often what we refer to as pump failure.
Our heart is that pump that's primarily responsible for moving the blood throughout our body, and in cardiogenic shock, that's just not working. And so like with everything else, I've got a picture here that I've put together of the heart, and we'll use this to talk about some of the causes of cardiogenic shock. Alright, so when we start talking about the causes, we really need to know that there are primarily four main causes of cardiogenic shock. So the first of these causes...
is going to be an issue with the filling of the heart. And essentially here, we're going to be talking about our diastolic heart failure. Now, I will get into explaining these here more in just a minute, but for now, I'm just going to list out these causes.
The second of these causes is going to be related to an issue with contraction. And some of these are going to be our cardiomyopathies, or our heart failures, as well as our myocardial infarction, or what we often call MI. Our third cause is going to be our arrhythmias. And there's many forms that this can come in, but essentially these are our conduction issues. And finally, the fourth and last cause that we're going to talk about here are what we categorize as our structural issues or structural defects.
And for this, we're really talking about our valvular diseases. And so for each of these causes, the pathophysiology is slightly different. But I do want to talk about the overall overarching theme.
And so as we talked about, the heart is essentially... not pumping blood forward as well as it should. And now in this case, unlike hypovolemic shock, we don't have a loss of volume. And so that blood is continuing to make its way around the body and ultimately returning back to the heart.
And so when that blood is not continuing forward like it's supposed to, what's going to happen is we're going to start to see things backing up. So initially things are going to be backing up in our left atrium. From there, we're going to continue to back into our pulmonary arteries and ultimately back up into our lungs. And eventually, that's going to lead into backing up into the right side of our heart.
And finally, from there, it will continue to back up throughout the rest of the body. And so now we'll go back and look at these different causes and talk about that pathophysiology that's ultimately leading to the pump failure. So in order to serve as a primer for this information, it helps to have a really good understanding of the cardiac output and all the components that are going into that.
So we do have a great lesson on that within our hemodynamics series, and I will go ahead and link to that above. So the first of these causes that we'll talk about are filling issues and most notably diastolic heart failure. And so what happens with diastolic heart failure is that we have a lot of heart failure.
heart failure is that over time, the ventricle walls become enlarged. They also become stiffer. And so as a result, you end up with less space within the ventricle, as well as decreased compliance within the heart wall.
And ultimately, what this means is you end up with a decreased preload, which ultimately leads to a decrease in cardiac output. Now when we talk about the contraction causes, there's two different things that we need to look at. The first are our cardiomyopathies or our heart failure.
And again, what happens is over time, the heart grows. But unlike diastolic heart failure, where we have the thickening of the walls, what happens with the enlargement of the heart is the heart actually becomes weaker. And as a result, over time, that contraction becomes weaker and weaker and weaker.
ultimately leading to a decreased contractility. So it's a very similar process when a patient has had an MI. So essentially they've had areas of their heart that have either suffered ischemia, or if things have been prolonged or been severe enough, ultimately muscle cell death. And once again, the heart is just not going to be able to beat or contract as well as it used to.
And so again, we'll find ourselves with a decreased contractility. Now when talking about arrhythmias, there's really several different things that can be happening that could be impacting our ability of our heart to pump. So as we know, we have our SA node and our AV node, our bundle of his. And normally those pacemakers in the SA node initiate contraction in the atria.
which is passed along to the AV node, ultimately down to the bundle of his, and out to the heart itself. But all along in this process, there can be multiple issues that come up. We can have bradycardia arrhythmias that are ultimately a result of conduction issues.
We can also have tachycardia issues, and these are both on the atria and the ventricle side. And ultimately, any sort of... dyssynchrony between both the atria and the ventricle is going to have an impact.
And so with those arrhythmias, if we lose that atrial kick, that's going to impact our preload. Also in the case of our heart blocks or conduction issues and the ventricle is initiating the contraction, you end up with a very different contraction than if that signal had passed rapidly through the bundle of his and out the Purkinje fibers. And so that ultimately could impact our contractility, as well as when we look at the cardiac output equation, if we are having bradycardia issues, that's going to be impacting our heart rate, and again, ultimately our cardiac output.
So again, there's several different things and lots of different processes that can be going on and really contributing to this malfunctioning of our heart. And now finally for the structural causes, like we talked about, the main thing we're looking at is various valvular diseases. Most importantly for this particular lesson is going to be our regurgitation. And that's essentially where you have an incompetent valve here that just does not close all the way.
And as a result, you're going to get a backflow of blood during the time the heart should be filling as well as during contraction. which will take away from that blood that is being ejected forward and ultimately reducing our cardiac output. And so again for this here, we are talking about a decreased preload.
Now I will take a quick minute here to point out that there are other causes of pump failure, and depending which source you're looking at, it may classify those within the overall cardiogenic shock picture. But for the purpose of these lessons, we actually subdivide these out into another process, another subcategory of cardiogenic shock that we call obstructive shock, and we will talk about that in the next lesson. And so hopefully at this point you have a pretty good idea of some of the causes and what's really happening in cardiogenic shock, and that the blood is just not moving forward for various reasons, and ultimately is not able to perfuse the rest of our body. And so what we'll do is we'll go ahead and move on to some of our signs that you'll see with a patient that is in cardiogenic shock. Now the first of these is actually a symptom that your patient will be experiencing, but they will be having angina.
essentially chest pain. And again, like with all forms of shock, the most obvious sign is going to be our decreased blood pressure or hypotension. As a result, the body's compensation mechanisms are going to kick in and we're going to see an increased heart rate or tachycardia. And again, as a part of that compensatory mechanism, you're going to see that peripheral vasoconstriction and ultimately end up with cool, clammy skin. And now along with that, like we had talked about, the flow of blood is going to begin to back up.
We're going to start seeing things like cardiomegaly. And as the blood continues to back up into the pulmonary arteries and ultimately the lungs, we're going to start to see pulmonary edema. And this will often manifest itself in coughing as well as bloody and frothy sputum.
Your patient will eventually develop... jugular venous distension, or JVD, which as that blood begins to back up throughout the rest of the body, you'll see a swelling and extension of the veins in the neck, as well as as that blood continues to back up everywhere else, you'll also see peripheral edema. And so now let's move on and talk about some of the lab tests and things that we're going to look to do to try and diagnose what's going on.
So again we're going to want to check the serum lactate level and again checking to see if we've switched into that anabolic process or how far along it is. We'd also want to run an arterial blood gas and assess our oxygenation. In addition though we're also going to want to check some troponins as these are going to be an indicator of damage to the heart. Now we typically aren't going to see these begin to rise for a few hours, but they can be a good indicator as far as what is potentially going on. Along with these lab tests, we could also get a chest x-ray.
We could use this to look for the pulmonary congestion. You may want to get an EKG, and this is either to assess or diagnose some sort of arrhythmia, or also checking to see if the patient has had a myocardial infarction. And ultimately, our gold standard is our echo, which will give us a great picture of what is going on with the heart on many levels and can really help to tell us what exactly the cause is in order to try to figure out how to fix it. Along with that, we also want to be watching some of our hemodynamic values. So things as simple as a CVP or watching for that elevated CVP can be a sign that fluid is beginning to back up into the peripheral circulation.
As well as if you have a swan GANS or a PA catheter, you want to be looking at that pulmonary capillary wedge pressure and essentially looking at the left side of our heart and seeing if the blood and fluid are beginning to back up from there. And finally, we're also going to be looking at our cardiac output and cardiac index. And this is again where that swan GAN catheter will be able to give us that information, although there are also other ways in order to get this information as well.
And essentially, based on the results of these various diagnostic tests, you will be able to not only confirm that your patient is in cardiogenic shock, but potentially determine what the cause of that is and work to treat it. And so now let's go ahead and move on and talk about just that, the various treatment modalities for cardiogenic shock. And so for these, the first and most basic treatment that we're going to do is to ensure that we are supplying adequate oxygen. Because again, our perfusion has decreased, and ultimately the shock state is a result of the lack of oxygen delivery. So we want to ensure that we have as much oxygen available to our patient and their body as possible.
So the next thing that we're going to really want to look at in treating our patient with cardiogenic shock is our cardiovascular support. And this is really going to come in the way of a few different things. So first we're going to look to increase that systemic vascular resistance.
And this is primarily going to be done through our vasopressors. So we're talking things like levo, neo, vaso, potentially epinephrine. And the next thing we're going to want to look at to support is to increase our contraction. And here we're really talking about our inotropes.
And so that's going to be things like our dibutamine and our primacor. Now, in addition to those, epinephrine, which we potentially are using to increase our SVR, can also have a positive impact on the contractility of the heart and sometimes serves as a dual purpose in this. Now, in addition to these, depending on what is going on with your patient, you may also need to be looking at fixing arrhythmias. And this could be for our heart rate, perhaps increasing our heart rate with dopamine.
Epi is another good alternative here, as well as some of the other vasopressors, which have that positive chronotropic effect. But we might also be looking at some antiarrhythmics, such as our amiodarone, lidocaine, procanamide, as well as in the case of a ventricular tachycardia that we often are going to look at cardioversion. And just to take a look back at our heart rate, we also want to look at options such as pacing, both internally, externally, or with a permanent pacemaker. And finally, for the last of our cardiovascular support, we may need to look at some sort of temporary assist device, something that can not only rest the heart, but also handle taking over the job of moving blood throughout the body or perfusing the body.
And so here we're looking at things like the intra-aortic balloon pump, possibly an impella. as well as possibly going to VA ECMO and just completely taking over for the heart. And so at this point, you know, we've worked to ensure our patient has enough oxygen.
We've put interventions in place via our cardiovascular support. But in order to reverse the course of shock, we ultimately have to fix the underlying cause. And so that means that we do need to repair the heart.
Now, depending what is going on and what the cause is, in the case of myocardial infarction, we are often going to go to the cath lab in order to have the percutaneous coronary intervention, or PCI as we call it, in order to relieve the blockage. This could also require open heart surgery. This could either be in the case of a cabbage for some sort of vessel disease, or even a valve repair or replacement. in the case of a structural disease.
In some cases, there is no ability to repair the heart, and so we need to look at some sort of assist device on a more permanent basis. And this could potentially be things like a left ventricular assist device or an LVAD or total artificial heart or some sort of mechanical heart replacement. And finally, sometimes those devices are used as a bridge with the ultimate goal of a heart transplant.
And so ultimately we fix the problem with the pump in order to resolve the shock state and return normal functioning or normal perfusion at least back to the body. All right, well that was quite a bit that we covered here in cardiogenic shock. Like I said, the main takeaway from this is to know that this is a pump failure or a lack of the heart's ability to pump blood, perfuse blood throughout the body.
In this lesson we talked about the main causes for cardiogenic shock. We talked about some of the signs that you would see in your patient when they are in cardiogenic shock, as well as some of the diagnostic tests and procedures in order to determine what's going on. And finally, we covered the treatment modalities in terms of support as well as ultimately fixing the underlying problem.
I hope at this point you have a better understanding of the process and what's going on in cardiogenic shock and hopefully can take that and apply that to your practice all right and so with all of that said i do want to thank you for watching today again i hope this lesson was informative for you as always if you like the video and you did find it useful make sure and hit that like button below as it really does help get the word out about our channel as well as in the comments below tell us your favorite part or what you learned in this lesson As well as feel free to ask any questions that may come up. Finally, make sure and check out our next lesson in this series covering obstructive shock. Or you can always check out another one of our great series of lessons on hemodynamics.
As always, thank you for watching and we'll see you guys in the next lesson.