Pericardial Effusion: Causes & Treatment

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  • 0:01 Fluid Around the Heart
  • 0:30 Pericardial Effusion
  • 2:38 What Happens During…
  • 4:59 Clinical Signs and Diagnostics
  • 8:05 Two Major Treatment Options
  • 8:38 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Can the heart swing inside of your body? Maybe. You'll find out for sure in this lesson as we take a look at the pericardium, pericardial effusion, and cardiac tamponade!

Fluid Around the Heart

If I told you that the heart is filled with fluid then you'd probably give me a 'Duh!' type of look. Of course it is; it's filled with blood that it's constantly pumping! But what if I told you that fluid can also build up around the heart, not just inside of it, and that this type of fluid buildup can result in death? Well, unfortunately this can happen, it does happen, and there are many reasons for it that we'll be taking a look at right now.

Pericardial Effusion

The presence of an abnormal amount of fluid in the pericardial space is known as pericardial effusion. The word 'pericardial' references the pericardium, which is a strong, inelastic, and double-walled membranous sac that encloses the heart and partially regulates its health and function.

There are two main layers to the pericardium. The strong, protective, and outermost layer of the pericardium is known as the fibrous pericardium. The inner layer of the pericardium lining the pericardial cavity and the layer that secretes a lubricating fluid known as serous pericardial fluid is known as the serous pericardium.

The serous pericardium is itself divided into two layers. The layer that is directly internal to the fibrous pericardium is called the parietal layer. The layer that is directly external to the heart muscle (the myocardium) is called the visceral layer and is also known as the epicardium.

In between the two layers of the serous pericardium is the pericardial cavity. It is normally filled with a little bit of serous fluid to make sure the heart doesn't rub itself raw during movement. But when there is too much fluid or an abnormal type of fluid in the pericardial cavity, we term that a pericardial effusion.

Don't get yourself too caught up in all of those definitions above; they're just there for your reference if you need them. What I want you to understand for this lesson is that our heart is surrounded by an important protective layer, the pericardium. Just think of the pericardium as the tough skin that protects your favorite fruit - sort of like apple skin, or a banana peel, or what have you.

Anyways, the things that can cause a pericardial effusion are many and many times involve pericarditis, or the inflammation of the pericardium. These include:

  • Infections due to viruses such as HIV or bacteria
  • Cancer
  • Many times, idiopathic causes (or unknown causes)

What Happens During Pericardial Effusion

If the pericardial cavity fills with too much fluid, the pressure in the pericardial cavity rises to improper levels. This pressure is like a fist squeezing around the heart really tightly. Go ahead and squeeze your fist really tightly around a deflated balloon. Just try and fill it with air. It'll be very hard. In our case, it'll be really hard for the heart to fill with blood.

What I mean is, the excess fluid around the heart exerts a big force that prevents the heart from properly opening up. If the heart chambers can't open up because they're being squeezed shut, then they cannot fill with enough blood. If they can't fill with enough blood, then when they contract not enough blood is sent into circulation in order to keep you alive. In short, pericardial effusion diminishes stroke volume and therefore cardiac output.

If this process occurs quickly due to something like hemorrhage (bleeding), then it can lead to a condition known as cardiac tamponade. This is a serious restriction of heart motion and function as a result of an acute pericardial effusion.

In essence, the pericardial cavity fills so quickly and compresses the heart so fast, it leads to massive hemodynamic compromise because the heart cannot fill normally during its diastolic, or relaxed, filling phase. If it can't fill up on blood during the diastolic phase, then when it contracts during its systolic phase, it'll only spit out a tiny amount of blood, not enough for survival. This is why cardiac tamponade is oftentimes fatal.

Now, if the pericardial effusion occurs over a long period of time, then the pericardium can actually stretch out in order to accommodate a lot of fluid in the pericardial cavity, sort of like people's skin stretches out over a long period of time if they gain too much weight - same deal here.

Clinical Signs and Diagnostics

As a result of all of this, pericardial effusion can cause:

  • Muffled heart sounds - it's kind of hard to hear things underwater, so it's kind of hard to hear the heart well with a stethoscope if it's surrounded by a ton of fluid.
  • Furthermore, jugular distension can occur. Your jugular veins drain blood into your heart, but because the blood backs up in the veins since it can't enter the heart as it's being squeezed shut, then the jugular veins become engorged and distended with blood instead.
  • Another problem that can occur is hypotension, or low blood pressure, because little blood is leaving the heart since little is getting in in the first place.

These three signs (hypotension, muffled heart sounds, and jugular distension) are known as the classic Beck triad of cardiac tamponade. Other signs include:

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