Synchronized Cardioversion

zambezi, BSN, RN · Apr 4, 2005

Hello everyone,
I am new here. I was searching the internet for information on shocking someones heart back into rythm who has A-Fib, when I came across this site.
My mother, age 75, had pericarditis last September. We got her through that well enough. The Dr. put her on Metropolol and baby aspirin. In the last month she has been put on Coumadin and High Blood Pressure medication Altace.
She was also told that she has Atrial Fibrillation. The Dr. told her in about 3 months he is going to try shocking her heart back into rythm. I have just learned that it is called Synchronized Cardioversion. Does anyone know if there are side effects or dangers?
Thank you for your help. (End Quote)
I posted a couple of links below (at the bottom)...one is about atrial fibrillation and one is about cardioversion. The other is kind of a mix between the two...I don't know your background so they are in "layperson" terms and fairly easy to understand.
When the heart is functioning normally, it starts it's electrical impulse in a little area known as the hearts primary pacemaker- or the sinoatrial node (SA node). The SA node is located in the upper right corner of the heart and usually generated impulses 60-100 times a minute. These impulses are supposed to follow a specific path through the heart which generates the heart's normal (or sinus) rhythm. When the impulse leaves the SA node, it goes down through the atria (the top two chambers of the heart) down various pathways through the atrioventricular node (AV node- which can also function as a "back up" pacemaker) and into the ventricles down through the bundle branches and purkinje fibers (all parts of the conduction system). The AV nodes main funtion is to delay impulses from the SA node to keep the ventricles from contracting too quickly. The delay allows the ventricles to complete their filling phase as the atria contract. The heart can't pump unless an electrical stimulus occurs first and the generation and transmission of these impulses depends on the special characteristics of the cardiac muscle.
Atrial fibrillation is one of the most common cardiac arrhythmias. It is "chaotic", asynchoronous, "quivering" (like a bowl of jello) electical activity in the atrial tissue. It results from impulses origingating in areas outside of the SA node (this can occur due to the other special characteristics that the cardiac muscle has). Some people can do quite well if the atrial fibrillation (afib) is controlled but some tolerate the atrial fibrillation very poorly. This type of arrhythmia can affect the ventricular filling time (usefuly for optimal cardiac output, etc) and diminish the stregnth of the atrial kick (which comes from the normal conduction of the atria)-- this atrial kick normally gives the ventricles about 30% of their blood. The decreased amount of blood to the ventricles (and thereby the rest of the body) coupled with a fast rate means that a person has the potential to feel pretty icky as this can cause clinically significant problems. One can develeop chest pain (angina), heart failure, or syncope (fainting) from this arrhythmia. It can even lead to shock or severe heart failure if the patient has prior cardiac issues.
These abnormal impulses can fire at a rate of 400-600 times a minute (way over the 60-100 beats a minute of the normal packemaker).The ventricles respond only to those imulses that make it through the AV node. Because the atria is beating so fast, the ventricular rhythm is irregular. The rate can range from normal to very, very fast. This type of rhythm can occur from various conditions/reasons and your mothers doctor can discuss those with her.
The major goals of therapy to treat artial fibrillation are to either control the rhythm-> assist the patient in converting back to the normal sinus rhythm (either by "luck"/no treatment, medications, or cardioversion or the medication/cardioversion combo) or by controlling the rate at less than 100 beats per minute. Typically if the patient remains in afib, they will be well anticoagulated (asa/coumadin) before trying to convert them back to a normal rhythm as the risk for stroke increases with afib due to the ventricles inability to eject all of the blood. The "stagnant" blood more easily forms clots that can be thrown to various parts of the body so anticoagulation that is within the therapeutic range is pretty important.
Electrical cardioversion is used if the patient is symptomatic from the afib (they are probably waiting to see if you mom's afib converts with meds...they are also waiting for her to be optimally anticoagulated, I would guess). If she were to become symptomatic they would weigh the risks/benefits or immediate cardioversion. The cardioversion is done by placing patches on the cchest and an electrical shock is delivered to "reset" the heart by stopping the aberrent pathways. Cardiac arrest is always a possibility (and the doctor should discuss all of the risks/benefits with you and your mother) but the team is aware that it can happen and is ready for it should it occur. Usually there will be a nurse, doctor and respiratory therpaist at the bedside monitoring the cardiac rhythm, respiratory status, blood pressure, etc. Those undergoing cardioversion are typically given something for sedation/pain to help keep them comfortable. The amount of electricity used can vary depeding on how long she has had the afib, what type of defibrillator is used, etc. I usually see someone convert in one to three shocks- some people will convert to the normal rhythm and then back into afib. If you mom were to remain in afib despite multiple cardioversion attempts then the doctor would go for rate and symptom control with medication. If she were cardioverted back to a normal rhythm, she would probably be kept on meds in order to help her heart stary in a normal rhythm...of course it depends on what else she has going on too, whether there are other cardiac or major body system issues, etc---those are all good questions for her doctor...On another note, I had a good friend that just had this done due to very symptomatic afib and he said that as soon as his heart "went back to normal' he immediately felt better (and he looks better too...)
I am sending you and your mom good thoughts. Please remeber to ask your doctor all questions that you might have (write them down if you can't remember them in the office)- this site is a great place for additional information but talking with the primary health care provider is the best option so you understand the plan of care, risks, benefits, and options.
http://www.nlm.nih.gov/medlineplus/ency/article/000184.htm
http://www.annals.org/cgi/content/full/139/12/I-32
http://patients.uptodate.com/topic.asp?file=hrt_dis/5982
http://patients.uptodate.com/topic.asp?file=hrt_dis/4882

Bevvie · Apr 4, 2005

Hi Zambezi,

Thank you so much!!! This was very informative and I will be sure to let my mother know all about this. I will make sure that she writes a list of questions for her Dr.

Bev E.

ehrharba · Apr 26, 2005

Cardioversion is an electrical shock that is synchronized so that only the atria are affected - not the ventricles- as in defibrillation. The hope is that once the atria are depolorized at the same time the SA node will reassert itself as the pacemaker.It does require moderate sedation, and is over quickly. The joules that are used are about 100. However the inderlying cause of the atrial fib has not changed it is not unusual for patients to reconvert to the atrial fib.

Hello everyone,
I am new here. I was searching the internet for information on shocking someones heart back into rythm who has A-Fib, when I came across this site.
My mother, age 75, had pericarditis last September. We got her through that well enough. The Dr. put her on Metropolol and baby aspirin. In the last month she has been put on Coumadin and High Blood Pressure medication Altace.
She was also told that she has Atrial Fibrillation. The Dr. told her in about 3 months he is going to try shocking her heart back into rythm. I have just learned that it is called Synchronized Cardioversion. Does anyone know if there are side effects or dangers?
Thank you for your help.
Bev E.