Cardioversion
People often refer to the heart as if it were the seat of certain strong emotions. A person who is very determined is described as a person who has ‘a lot of heart’ and the person who’s been disappointed romantically is called as ‘broken-hearted’. The heart is a delicate part of our body which is a muscular organ that is essential for life because it pumps blood through the body (Seeley, et. al, 2008). Emotions are a product of brain function, not heart function.
Our heart has several functions which include generating blood pressure, routing blood, ensuring one-way blood flow, and regulating blood supply.
Our heart also has electrical activity, it exhibits depolarization followed by repolarization. Depolarization is a process by which cardiac muscle cells change from a more negatively charged to a more positively charged intracellular state. Repolarization, on the other hand is a process by which cardiac muscle cells return to a more negatively charged intracellular condition, their resting state.
Without a regular rate and rhythm, the heart may not perform efficiently as a pump to circulate oxygenated blood and other life-sustaining nutrients to all of the body’s tissues and organs (including the heart itself). With an irregular or erratic rhythm, the hearty is considered to be dysrhythmic (sometimes called as arrhythmic). This has the potential to be a dangerous condition. (Smeltzer, et. al, 2008)
Dysrhythmias are disorders of the formation and/or conduction of the electrical impulse within the heart. There are a lot of different types of dysrhytmias which include sinus, junctional, and ventricular dysrhythmias with their various subcategories.
Treatments for dysrhythmias depend on whether the disorder is acute or chronic as well as the cause of it and its actual or potential hemodynamic effect. Acute dysrhythmias may be treated with medications or with external electrical therapy which can be emergency defibrillation, cardioversion, or pacing. The choice of medication depends on the specific dysrhythmia and its duration, the presence of heart failure and other diseases, and the patient’s response to previous treatment. The nurse is the one responsible in monitoring the response of the patient and documenting it, and for ensuring that the patient has the knowledge and ability to manage the medication regimen. Some of the most commonly used medications for arrhythmias are quinidine, procainamide, disopyramide, lidocaine, tocainide, mexiletine, phenytoin, flecainide, propafenone, encainide, and moricizine which are classified as sodium channel blockers; the ß-Adrenergic blockers which include propranolol, acebutolol, esmolol, sotalol; agents that prolong Phase 3 – bretylium, amiodarone, ibutalide, sotalol, dofetilide; the Calcium channel blockers – verapamil and diltiazem; the Digitalis glycosides which increase the slope of Phase 4 – digoxin and digitoxin; and the Adenosine which reduces SA node automaticity and AV node conduction. These agents cause several adverse effects which needs the nurse to monitor them. These drugs may make the patients get better, make them get better with some side effects, or make them worst. So, the nurse must always remember that proper dosage, route, and interventions must be always followed. In case there are adverse effects happening to the patient after the intake of the drug, immediately call the physician for further management.
If any of the mentioned drug/s are not effective in eliminating or decreasing the dysrhythmias, certain adjunctive mechanical therapies are available. The most common are elective cardioversion and defibrillation for acute dysrhythmias, and implantable devices called the pacemakers for bradycardias and internal cardiodefibrillators for chronic tachycardias. In these cases, the nurse is responsible for assessing the patient’s understanding of and response to mechanical therapy, as well as the patient’s self-management abilities. The nurse explains that the purpose of the device is to help the patient lead an active and productive life as his or her overall health allows.
Cardioversion and defibrillation are used to treat tachycardia by delivering an electrical current that depolarizes a critical mass of myocardial cells. When the cells are repolarized, the sinus node is usually able to recapture its role as the heart’s pacemaker. In cardioversion, it involves delivery of a ‘timed’ electrical current to terminate a tachydyrhythmia. With this therapy, the defibrillator is set to synchronize with the electrocardiogram (ECG) on a cardiac monitor so that the electrical impulse discharges during ventricular depolarization.
If the cardioversion is elective and the dysrhythmia has lasted longer than 48 hours, anticoagulation for a few weeks before cardioversion may be indicated. The patient is instructed not to eat or drink for at least 4hours before the procedure. Gel-covered paddles or conductor pads are positioned anteroposteriorly for the therapy. Before the procedure, the patient receives IV moderate sedation as well as analgesic medication or anesthesia. Respiration is then supported with supplemental oxygen delivered by bag-mask-valve device with suction equipment readily available. Although patients rarely need intubation, the intubation set must be readily available at bedside.
For the cardioversion to be considered successful, the patient should have the sinus cardiac rhythm, adequate peripheral pulses, and adequate blood pressure. Airway patency must be maintained and the state of consciousness must be assessed due to sedation. Vital signs and oxygen saturation are monitored and recorded until the patient is stable and recovered from sedation and analgesic or anesthesia. ECG monitoring is also required during and after the procedure. [i]
[i] Smeltzer, S, Bare, B., Hinkle, J.,Cheever, K., 2008. Brunner & Suddarth’s Textbook of Medical-Surgical Nursing. 11th edition. Lippincott Williams & Wilkins
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