Countershock

Primary indications for the use of quinidine include (1) abolition of premature complexes that have an atrial, A-V junctional, or ventricular origin (2) restoration of normal sinus rhythm in atrial flutter and atrial fibrillation after controlling the ventricular rate with digitahs (3) maintenance of normal sinus rhythm after electrical conversion of atrial arrhythmias (4) prophylaxis against arrhythmias associated with electrical countershock (5) termination of ventricular tachycardia and (6) suppression of repetitive tachycardia associated with Wolff-Parkinson-White (WPW) syndrome. 

Following inhalation overexposure, a calm environment with no physical exertion is imperative to avoid an endogenous adrenaline surge. Exogenous adrenergic drugs should not be used to prevent induction of sensitized myocardial dysrhythmias. Dip-henylhydantoin and countershock may be effective for ventricular dysrhythmias. 

Harrison EE. Lidocaine in prehospital countershock refractory ventricular fibrillation. Ann Emerg Med 1981 10 420M23. 96. 

Ornato JP, Gonzalez ER, Morkunas AR, et al. Treatment of presumed asystole during prehospital cardiac arrest Superiority of electrical countershock. Am J Emerg Med 1985 3 395-399. 

Acute treatment of TdP is different from treatment for the more common acute monomorphic ventricular tachycardia (or polymorphic VT with a normal QT interval). For an acute episode of TdP, most patients will require and respond to DCC. However, TdP tends to the paroxysmal in nature and often will recur rapidly after countershock. Therefore, after the initial restoration of a stable rhythm, therapy designed to prevent recurrences of TdP should be instituted. Drugs that further prolong repolarization such as intravenous procainamide are absolutely contraindicated. Lidocaine usually is inef-... 

For ventricular fibrillation, immediately apply direct-current countershock at 3-5 J/kg. Repeat twice if no response. Continue CPR if the patient is still without a pulse, and administer epinephrine, repeated countershocks, amiodarone, and/or lidocaine as recommended in advanced cardiac life support (ACLS) guidelines. 

For ventricular tachycardia in patients without a pulse, immediately give a precordial thump or apply synchronized direct-current countershock at 1-3 J/kg. If this is not successful, begin CPR and apply countershock at 3-5 J/kg administer amiodarone and/or lidocaine and repeated counter-shocks as recommended in ACLS guidelines. 

For patients in cardiac arrest, usual antiarrhythmic agents and direct-current countershock are frequently ineffective until the core temperature is above 32-35°C (90-95°F). Provide gastric or peritoneal lavage with warmed fluids and perfonn CPR. For ventricular fibrillation, bretylium, 5-10 mg/kg IV (see p 421), may be effective. 

Excludes events involving planned treatments such as electric countershock. 

Jones DL, Sohla A, Bourland JD, Tacker WA, Kallok MJ, Klein GJ. Internal ventricular defibrillation with sequential pulse countershock in pigs comparison with single pulses and effects of pulse separation. Pacing Clin Electrophysiol 1987 10 497-502. 

Dahl CF, Ewy GA, Warner ED, Thomas ED. Myocardial necrosis from direct current countershock effect of paddle electrode size and time interval between discharges. Circulation 1974 50 956-960. 

Das G, Eaton J. Pacemaker malfunction following transthoracic countershock. Pacing Clin Electrophysiol 1981 4 487 90. 

Ironically, the treatment for cardiac arrest induced by an electric shock is a massive countershock, which causes the entire heart muscle to contract. The random and uncoordinated ventricular fibrillation contractions (if present) are thus stilled. Under ideal conditions, normal heart rhythm is restored once the shock current ceases. The countershock is generated by a cardiac defibrillator, various portable models of which are available for use by emergency medical technicians and other trained personnel. Although portable defibrillators may be available at industrial sites where there is a high risk of electrical shock to plant personnel, they should be used only by trained personnel. AppHcation of a defibrillator to an unconscious subject whose heart is beating can induce cardiac standstill or ventricular fibrillation, just the conditions that the defibrillator was designed to correct. 

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