Cardioversion direct current

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... 

DCC, direct current cardioversion IV, intravenously LVEF, left ventricular ejection fraction TEE, transesophageal echocardiogram. 

DCC, direct current cardioversion HF, heart failure LVEF, left ventricular ejection fraction VT, ventricular tachycardia. (Algorithm adapted with permission fromTisdaleJE, Moser LR. Tachyarrhythmias. In Mueller BA, Bertch KE, DunsworthTS, et al. (eds.) Pharmacotherapy Self-Assessment Program, 4th ed. Kansas City American College of Clinical Pharmacy 2001 21 7-267.)50... 

CAH Chronic active hepatitis DCC Direct-current cardioversion... 

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. 

If symptoms are severe and of recent onset, patients may require direct-current cardioversion (DCC) to restore sinus rhythm immediately. 

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

According to recent ACC/AHA/ESC Guidelines (see Zipes et al., 2006), in patients with sutained VT, direct-current cardioversion is appropriate and most effective, and also intravenous procainamide (or ajmaline in some European countries) is recommended as a reasonable choice for initial treatment for sustained monomorphic VT in patients with acute coronary syndrome. Intravenous amiodarone or lidocaine may be reasonable chose as alternative treatment. 

NPV = negative predictive value PPV = positive predictive value ACS = acute coronary syndrome PTCA = percutaneous transluminal coronary angioplasty PCI = percutaneous coronary intervention DCCV = direct-current cardioversion A fib = atrial fibrillation NA = not applicable. 

Roy D, Quiles J, Sinha M, et al. Effect of direct-current cardioversion on ischemia modified albumin levels in patients with atrial fibrillation. Am J Cardiol 2004 93 366-368. 

Coronary vasospasm Intracranial hemorrhage or Stroke Ingestion of sympathomimetic agents Direct myocardial damage Cardiac contusion Direct current cardioversion Cardiac infiltrative disorders Chemotherapy Myocarditis Pericarditis... 

Early cardioversion may be necessary in patients with hemodynamic compromise (acute pulmonary edema, worsening angina, or hypotension) in relation to uncontrolled AF (flow chart). Synchronized, direct current cardioversion is more effective and preferable to pharmacologic cardioversion under these circumstances. Intravenous anticoagulation should precede and follow the cardioversion (Fig. 2). 

Arnold AZ, et al. Role of prophylactic anticoagulation for direct current cardioversion in patients with atrial fibrillation or atrial flutter. J Am Coll Cardiol 1992 19(4) 851-855. 

Therapeutic uses Quinidine is used in the treatment of a wide variety of arrhythmias, including atrial, AV junctional, and ventricular tachyarrhythmias. Quinidine is used to maintain sinus rhythm after direct current cardioversion of atrial flutter or fibrillation and to prevent frequent ventricular tachycardia. 

FIGURE 6-1. Algorithm for the treatment of atrial fibrillation (AF) and atrial flutter. °lf AF <48 hours, anticoagulation prior to cardioversion is unnecessary may consider transesophageal echocardiogram (TEE) if patient has risk factors for stroke. Ablation may be considered for patients who fail or do not tolerate one antiarrhythmic drug (AAD). Chronic antithrombotic therapy should be considered in all patients with AF and risk factors for stroke regardless of whether or not they remain in sinus rhythm. (BB, 8-blocker CCB, calcium channel blocker p.e., verapamil or diltiazem] DCC, direct-current cardioversion.)... 

Direct current cardioversion increases the risk of digitalis-induced dysrhythmias, but digitalis treatment is not a contraindication to cardioversion (151). 

FIGURE 17-6. Algorithm for the treatment of atrial fibrillation and atrial flutter. Sx = symptoms AVN = AV node DCC = direct-current cardioversion CCB = calcium channel antagonist (verapamil or diltiazem) BB = jS-blocker ASA = aspirin OHD = organic heart disease AADs = antiarrhythmic drugs INR = international normalized ratio MVD = mitral valve disease CHF = congestive heart failure HTN = hypertension DM = diabetes mellitus. 

AVID Antiarrhythmic drug Versus Internal Defibrillator trial CAST Cardiac Arrhythmia Suppression Trial DCC direct-current cardioversion EADs early after-depolarizations... 

Murdock DK, Schumock GT, Kaliebe J, et al. Clinical and case comparison of ibutilide and direct-current cardioversion for atrial fibrillation and flutter. Am J Cardiol 2000 85 503-506. 

There are a variety of conditions that can increase the myocardial capture threshold. These include metabolic derangements, medications, and traumatic events such as inadvertent conduction of current down the lead during direct current cardioversion or defibrillation that results in tissue injury at the lead-tissue interface. Metabolic disturbances that increase the myocardial capture threshold include myocardial ischemia and infarction, hyperkalemia, hypoxemia, hypercarbia, acidemia, alkalemia, hyperglycemia, and hypothyroidism (59-62). Hyperkalemia is the most common electrolyte abnormality that can leads to failure to capture (Fig. 16.7), and the threshold typically increases when the serum potassium concentration exceeds 7.0mEq/L (63-65). Increasing the stimulus output is only variably successful and should not be relied on. Inunediate reversal of hyperkalemia should be the first priority. 

Waller D, Calhes E, Langenfeld H. Adverse effects of direct current cardioversion on cardiac pacemakers and electrodes. Is external cardioversion contraindicated in patients with permanent pacing systems Europace 2004 6 165-168. 

Treatment of intoxication is supportive. No specific antidote is presently known. M-cholinoblockers (atropine) are indicated to treat bradycardia. Amiodarone and flecainide can be recommended for the treatment of aconitine-induced arrhythmia. Ventricular arrhythmias provoked by aconitine are often refractory to direct current cardioversion and antiarrhythmic drugs. In refractory cases of ventricular arrhythmias and cardiogenic shock, the cardiopulmonary bypass is recommended. 

---