What is an electrical cardioversion?
· Brief procedure where an electrical shock is delivered to the heart to convert an abnormal heart rhythm back to a normal rhythm (Sinus Rhythm).
· “Non-emergency": to treat atrial fibrillation or atrial flutter, benign heart rhythm disturbances originating in the upper chambers (atria) of the heart.
· Emergency situations: to correct a rapid abnormal rhythm associated with faintness, low blood pressure, chest pain, difficulty breathing, or loss of consciousness.
Why do I need a cardioversion?· In atrial fibrillation, however, the atria fibrillate (or "quiver") due to chaotic electrical signals that circulate throughout both atria. This typically results in a fast and irregular heartbeat.
· While some patients have no symptoms, others may experience shortness of breath, lightheadedness and fatigue.
· Depending on your specific medical history and symptoms, your physician may recommend a cardioversion to return your heart to a normal rhythm.
· "Chemical" or "electrical".
o Chemical cardioversion
§ Use of antiarrhythmia medications to restore the heart's normal rhythm.
§ Mode of action: Modifying the heart's electrical properties to reduce the frequency of abnormal heart rhythms and to help restore a normal rhythm.
§ May start your antiarrhythmia medication as an outpatient, or may choose to give you an intravenous (IV) or oral antiarrhythmia medication while heart rhythm is monitored.
o Electrical cardioversion
§ a.k.a "direct-current" or DC cardioversion)
§ M.O.A: A synchronized (perfectly timed) electrical shock is delivered through the chest wall to the heart through special electrodes or paddles that are applied to the skin of the chest and back
§ The goal is to disrupt the abnormal electrical circuit(s) in the heart and to restore a normal heart beat.
§ The shock causes all the heart cells to contract simultaneously, thereby interrupting and terminating the abnormal electrical rhythm (typically fibrillation of the atria) without damaging the heart.
§ This split second interruption of the abnormal beat allows the heart's electrical system to regain control and restore a normal heartbeat.
§ Special cardioversion pads are placed on your chest and back (or alternatively, both pads can be placed on the front of the chest). The pads are connected to an external defibrillator by a cable.
§ Patient under anesthesia/sedated – not conscious during the procedure
· A normal heart rhythm can be restored more than 90% of the time, although abnormal rhythms may recur in about half the patients within 1 year.
· The success of electrical cardioversion often depends on the duration of atrial fibrillation and the underlying cause (heart disease).
· Cardioversion is not appropriate for every patient with atrial fibrillation.
· Because the upper chambers of the heart are fibrillating (quivering) and do not squeeze uniformly in patients with atrial fibrillation, there is a potential risk that blood clots may form.
· The process of restoring a normal rhythm could potentially dislodge a blood clot from the heart resulting in a heart attack or a stroke.
· Thinning the blood prior to cardioversion can prevent most blood clots.
· Prior to performing a cardioversion, risk of blood clot formation is determined (and thus, your risk of stroke or heart attack) and an anticoagulant medicine is given.
· Blood must be adequately thinned for at least 3-4 weeks prior to the cardioversion to reduce the risk of stroke.
· Because it takes many hours for blood clots to form, cardioversion can be safely performed without blood thinning medication in patients who have had their heart rhythm problem for less than 48 hours.
· Transesophageal echocardiogram or TEE may be used to allow the atria to be visualized and thus scan for potential blood clots.
· Typically, anticoagulation is continued after the cardioversion for an additional 4 weeks to 6 months, even if the cardioversion is successful.
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