Cardioversion electrical

Duration of atrial fibrillation/atrial flutter >48 h or unknown, o Electrical or chemical cardioversion in a patient without adequate anticoagulation may cause embolization of atrial thrombi. 

Pharmacological agents play a secondary role to electric cardioversion in unstable patients. 

All antiarrhythmics can be proarrhythmogenic. Sequential use of more than one agent can result in an adverse drug event. Do not use more than one antiarrhythmic unless absolutely necessary. Electric cardioversion is preferred over a second antiarrhythmic if the initial agent fails. 

Direct current cardioversion is the process of administering a synchronized electrical shock to the chest. The purpose of DCC is to simultaneously depolarize all of the myocardial cells, resulting in interruption and termination of the multiple reentrant circuits and restoration of normal sinus rhythm. The initial energy level of the shock is 100 joules (J) if the DCC attempt is unsuccessful, successive cardioversion attempts maybe made at 200,300, and 360 J.14 Delivery of the shock is synchronized to the ECG by the cardioverter machine, such that the electrical charge is not delivered during... 

In patients who have experienced VT and are at risk for sudden cardiac death, implantation of an implantable cardioverter-defibrillator (ICD) is the treatment of choice.44 An ICD is a device that provides internal electrical cardioversion of VT or defibril -lation of VF the ICD does not prevent the patient from developing the arrhythmia, but it reduces the risk that the patient will die of sudden cardiac death as a result of the arrhythmia. Whereas in the past ICD implantation required a thoracotomy, these devices now may be implanted transvenously, similarly to pacemakers, markedly reducing the complication rate. 

Direct current cardioversion The process of administering a synchronized electrical shock to the chest to simultaneously depolarize all of the myocardial cells, resulting in restoration of normal sinus rhythm. 

Implantable cardioverter-defibrillator (ICD) A device implanted into the heart transvenously with a generator implanted subcutaneously in the pectoral area that provides internal electrical cardioversion of ventricular tachycardia or defibriUation of ventricular fibrillation. 

Electrical cardioversion It may be desirable to reduce the dose of digoxin for 1 to 2 days prior to electrical cardioversion of atrial fibrillation to avoid the induction of ventricular arrhythmias, but physicians must consider the consequences of increasing the ventricular response if digoxin is withdrawn. If digitalis toxicity is suspected, delay elective cardioversion. If it is not prudent to delay cardioversion, select the lowest possible energy level to avoid provoking ventricular arrhythmias. Lab test abnormalities Periodically assess serum electrolytes and renal function (serum creatinine concentrations) the frequency of assessments will depend on the clinical setting. 

Synchronized Electrical Cardioversion (Tachycardia w/ Pulses in Hemodynamic Instability) Adult... 

Remove the transdermal patch before cardioversion or defibrillation because the electrical current may cause arcing which can burn the patient and damage the paddles... 

Marcus GM, Sung RJ. Antiarrhythmic agents in facilitating electrical cardioversion of atrial fibrillation and promoting maintenance of sinus rhythm. Cardiology. 2001 95 1-8. 

McNamara RL, et al. Management of atrial fibrillation review of the evidence for the role of pharmacologic therapy, electrical cardioversion, and echocardiography. Ann Intern Med 2003 139(12) 1018-1033. 

Bianconi L, et al. Effects of oral propafenone administration before electrical cardioversion of chronic atrial fibrillation a placebo-controlled study. J Am Coll Cardiol 1996 28(3) 700-706. 

For effectual rhythm control, the first action is often to restore NSR acutely with a nonsurgical intervention called a cardioversion, by which the patient s heart is reset through the use of electrical current strategically delivered to the heart via external electrode pads. When atrial fibrillation is changed to a normal sinus rhythm, the patient is said to have been converted. The cardioversion process has a good success rate for achieving conversion however, patients must be anesthetized for the procedure, and the AF often returns. 

Cardiac ischaemia may trigger abnormal electrical activity, causing fibrillation. Defibrillators deliver a large DC shock across the heart (cardioversion), to arrest abnormal activity and allow re-establishment of sinus rhythm. 

A 34-year-old man developed palpitation, shortness of breath, and chest pain. He had smoked a quarter to a half an ounce of marijuana per week and had taken it 3 hours before the incident. He had ventricular tachycardia at a rate of 200/minute with a right bundle branch block pattern. Electrical cardioversion restored sinus rhythm. Angiography showed a significant reduction in left anterior descending coronary artery flow rate, which was normalized by intra-arterial verapamil 200 micrograms. 

Jessurun GAJ, Crijns HJGM, van Wijngaarden J. 1996. An unusual case of cardiac tamponade following electrical cardioversion. Int J Cardiol 53 317-320. 

Atrial flutter, benefiting by the vagus nerve action of shortening the refractory period of the atrial muscle so that flutter is converted to fibrillation (in which state the ventricular rate is more readily controlled). Electrical cardioversion is preferred. 

In the last case the authors did not discuss the possibility that the presence of digoxin (serum concentration 1.8 ng/ml) may have contributed the risk of cardiac dysrhythmias after electrical cardioversion is increased in the presence of digoxin (SEDA-8, 174), and the same might be true of chemical cardioversion. 

The presence of digitalis increases the risk of serious dysrhythmias after electrical cardioversion, even in the absence of frank toxicity (64). In order to minimize the risk of dysrhjdhmias in these circumstances digitahs should be withdrawn if possible a day or two before cardioversion and potassium depletion should be corrected. If cardioversion is required acutely, it has been recommended that low energies (for example 10 J) should be used initially (65). 

Ali N, Dais K, Banks T, Sheikh M. Titrated electrical cardioversion in patients on digoxin. Clin Cardiol 1982 5(7) 417-19. 

In a comparison of intravenous dofetihde (8 micrograms/kg n = 48), amiodarone (5mg/kg n=50), or placebo (n = 52) in converting atrial fibrillation or flutter to sinus rhythm in 150 patients, two patients given dofetilide had non-sustained ventricular tachycardias four had torsade de pointes, in one case requiring electrical cardioversion (53). 

The use of propafenone in atrial fibrillation (SEDA-23, 202) has been studied in a randomized, double-bhnd, placebo-controUed trial in 55 patients (17). The dose of propafenone was chosen according to body weight 450, 600, and 750 mg for those weighing 50-64, 65-80, and over 80 kg respectively. Propafenone converted atrial fibrillation to sinus rhythm significantly more quickly than placebo, and most patients given propafenone had converted by 6 hours. However, by 24 hours there was no significant difference between the two groups. Four patients had hypotension after propafenone, in three cases transiently. The patient with sustained hypotension had poor left ventricular systolic function, but it responded promptly to the administration of fluids and electrical cardioversion. In one patient with transient hypotension there was a brief episode of sinus bradycardia and in another an isolated sinus pause. 

Terfenadine is adsorbed by activated charcoal and charcoal may be considered for substantial recent ingestions. There is no antidote for terfenadine overdose. Terfenadine therapy should be discontinued and standard supportive therapies should be utilized as clinically necessary. Close electrocardiographic monitoring should be instituted for a minimum of 24 h. Torsades de pointes may be treated with electrical cardioversion if the patient is hemodynamically unstable. Otherwise, magnesium, isoproterenol, and/ or atrial overdrive pacing may be used to manage this arrhythmia. 

Figure 8.31 (A) A patient with an acute myocardial infarction with evident ST-segment elevation and frequent, polymorphic, repetitive, PVC that triggers VF (asterisk) that was resolved with cardioversion. (B) Primary ventricular fibrillation in a patient with acute Ml. VF appears suddenly, without previous PVC and without evident ST-segment elevation. However, the underlying sinus rhythm is fast, which can often be present in cases of primary ventricular fibrillation and express the sympathetic overdrive that is usually present in acute phase of Ml (see p. 252). The electric cardioversion resolved the problem.

Atrial fibrillation usually is self-limited thus, electric cardioversion is advised only when the heart rate is rapid and causes haemodynamic impairment. The P-wave late potentials technique may identify candidates for atrial fibrillation in ACS (Rosiak, Bolinska and Ruta, 2002). 

Patients with hemodynamically significant ventricular tachycardia or ventricular fibrillation not associated with an acute Ml who are resuscitated successfully (electrical cardioversion, pressors, amiodarone) are at high risk for death and should receive implantation of an internal cardioverter-defibrillator. 

Van Gelder IC, Hagens VE, Bosker HA, et al. The Rate Control Versus Electrical Cardioversion for Persistent Atrial Fibrillation Study Group A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. New Engl J Med 2002 347 1834-1840. 

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