Today was my first day on the floor in my acute care clinical. I spent the morning in the Cardiac Observation Unit at St. Luke’s downtown. I had the opportunity to start an IV, and to see a Transesophageal Echocardiogram, or TEE, followed by a direct current cardioversion.
The patient had atrial fibrillation, or a-fib, which means the atrium of the heart was not conducting current correctly so she had irregular atrial contraction. Atrial fibrillation is the most common dysrhythmia in the USA, affecting approximately 1 in 136 adults. Atrial rate can be over 350 beats per minute with a-fib, and ventricular contractions from 50-180 bpm. A-fib can cause pooling or collecting of blood in the atrium that increases the chance of blood clot formation. These blood clots can dislodge and pass to the brain and cause a stroke.
Top: A-fib heart rhythm, Bottom: Normal Sinus Rhythm
Atrial fibrillation can be treated with drugs to control the heart rate, or by cardioversion, which is a process of restarting the heart with a normal rhythm. There are two was to cardiovert; drugs or electrical shock. Both methods stop the heart and allow it to restart with a normal sinus rhythm. Many people falsely believe that defibrillators shock a heart to get the heart to beat. In reality, the shock delivered is meant to completely stop the heart, so its natural beat can start again.
The purpose of the transesophageal echocardiogram is to check to make sure no blood clots have formed. Cardioversion can break a blood clot loose. In the case that a blood clot were found, cardioversion would not be performed. A TEE is basically an ultrasound of the heart from inside the esophagus. The esophagus runs right next to the heart, and putting an ultrasound probe right next to the heart allows for incredible views of the heart chambers, valves, arteries, and veins.
The direct current cardioversion is performed with the same defibrillators that are used if a person is having a heart attack (we’ve all seen it on E.R.). Two pads are placed on the patient and a direct current is applied to the person, which can be a very “shocking” experience.
Here is a link to a video of a cardioversion. They shocked this guy several times, ending with 100 Joules. The doctor I observed today started with 100 Joules and only needed to shock this patient once. The patient was also sedated, so she didn’t feel a thing.
Lewis, S.L., Heitkemper, M.M., Dirksen, S.R., O’Brien, P.G., & Bucher, L. (2007). Medical-Surgical Nursing (7th ed.). St. Louis: Mosby Elsevier.
When I hear “Charging…..Clear” I think about something about to go “BOOM!”