Cardiac Tamponade

This has nothing to do with tampons in the heart ok! Just an FYI.

When blood or fluid accumulate in the sac which surrounds the heart it exerts pressure against the heart, making it harder for the heart to pump. As you can imagine, if the ventricles cannot fill fully or contract effectively then cardiac output decreases. Decrease cardiac output is not good news!

So how do you know if someone has this?

Well the symptoms are nothing unusual: chest pain, restlessness, quick shallow breathing, palpitations, pallor, tachycardia, weak peripheral pulses, pulsus paradoxical, distended neck veins, low BP… (do these all sound a little familiar? MI anyone?) Well causes of cardiac tamponade can be MI, Dissecting aortic aneurysm (thoracic), end-stage lung cancer, heart surgery, Pericarditis caused by bacterial or viral infections, or direct wounds to the heart.

How do we diagnose? Echocardiogram is the usual diagnostic tool, but MRI, CT, CXR or EKG can also highlight or confirm this.

Can you see the halo of fluid around the heart?

This is an emergency! The fluid must be drained to reduce damage to the myocardium and reestablish cardiac output.

Pericardiocentesis is a procedure that uses a needle to remove fluid from the pericardial sac, the tissue that surrounds the heart. The patient will be hyperoxygenated, given fluids to maintain blood pressure. It is important to note that a pericardiocentesis may have to be repeated because cardiac tamponade can return. With fast treatment the outcome is usual good, without treatment death is immanent.

A pericardial draining tube may be placed during surgery to keep in place postop. The drainage will be measured every shift and documentation on the color, amount and consistency is very important! The tube will usually be removed slowly over the postop recovery weeks at the discretion of the cardiologist.

EKG Time: I never see U waves?

Have you been diligently looking through EKG strips on your Telemetry unit trying to find a u wave? But they taught you in school it was apart of the EKG complex right? Well yes, but they are not seen all the time, which isn’t a bad thing, in fact it doesn’t really matter that much. We don’t talk about U waves very often because there isn’t really much to say, there are usually other “cardinal signs”, where a U wave can confirm something we can already see. Could be classified as last phase of ventricular repolarization or endocardial repolarization, but at the end of the day, we don’t really understand it fully though there are some things you should know about U waves:

• U waves follow T waves and should be about half the height of the T wave.
• The U wave should be less than 2 mm (2 tiny boxes on the EKG strip).
• They are mostly seen or more clearly seen, in sinus bradycardia, but if you can’t see them it’s ok!
• Best seen in leads V2, V3
• They can often interfere with the measurement of the QT intervals.

So you’ve found a EKG strip with some really cool U waves, you still need to know what the changes mean. The changes seen in U Waves (either prominent upright or depressed/inverted) are usually correlating to some other clearly visible change in the EKG (T waves changes, PR intervals or ST seg. changes). So what are some changes you should know about?

Inverted U waves are very myocardial focused. They usually mean trouble. Ischemic heart disease (often indicating left main or LAD disease) is one of a few serious readings that can come from a severely inverted U wave; Myocardial infarction (in leads with pathologic Q waves) and during a angina attack (acute ischemia or exercise-induced ischemia) they can also be present.

Upright waves (prominent ones that is) can mean Hypokalemia (remember the triad: ST segment depression, low amplitude T waves, and prominent U waves). There are times in pathological cases where the T and U wave can merge together to create a large wave, it makes it very tricky to know if it is a very large elevated T or a merge, look at the full picture, does this patient have a CNS disease or disease process going on? Then most likely it is a merge. Lastly, drugs. We all know that drugs interfere with all sorts of things, so what drugs could be messing with your U waves? Quinidine and other type 1A antiarrhythmics. Any drug that is acting on the heart can have adverse effects, but don’t forget to think about antipsychotics too! So keep this in mind when reading your EKG. Although you are focusing on a map of the heart, keep in mind that this is a patient, and every patient has a physiological story. The map you are looking at can tell you a snapshot of it’s current mapping system, but there are always other factors to consider.

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