For Rx of ventricular fibrillation in an adult, DC shock of what joules should be started with?
Ans. A (200 J). (Ref. Harrison, Medicine, 18th/ Ch. 233; fibg 233-11). Ref- Sustained polymorphic VT, ventricular flutter, and VF all lead to immediate hemodynamic collapse. Emergency asynchronous defibrillation is required with at least 200-J monophasic/100-J biphasic shock VENTRICULAR FLUTTER AND VENTRICULAR FIBRILLATION (VF) # These arrhythmias occur most often in patients with ischaemic heart disease. # Episodes of cardiac arrest recorded during Holter monitoring reveal that approximately three fourths of the sudden deaths are due to VT or VF. Types: # Ventricular flutter usually appears as a sine wave with a rate between 150 and 300 beats/min. # VF is recognized by grossly irregular undulations of varying amplitudes, contours, and rates. # VT originates below the bundle of His at a rate >100 beats per minute; most VT patients have rates >120 beats per minute. Sustained VT at rates <120 beats per minute and even <100 beats per minute can be observed, particularly in association with the administration of antiarrhythmic agents that can slow the rate. ECG Clues Supporting the Diagnosis of Ventricular Tachycardia # AV dissociation (atrial capture, fusion beats) # QRS duration >140 ms for RBBB type V1 morphology; V1>160 ms for LBBB type V1 morphology # Frontal plane axis -90Adeg to 180Adeg # Delayed activation during initial phase of the QRS complex # LBBB pattem-R wave in V1, V2>40 ms # RBBB pattern-onset of R wave to nadir of S >100 ms # Bizarre QRS pattern that does not mimic typical RBBB or LBBB QRS complex # Concordance of QRS complex in all precordial leads # RS or dominant S in V6 for RBBB VT # Q wave in V6 with LBBB QRS pattern # Monophasic R or biphasic QR or R/S in V1 with RBBB pattern TREATMENT: VENTRICULAR TACHY C ARDIA/FEBRILL ATION # Sustained polymorphic VT, ventricular flutter, and VF all lead to immediate hemodynamic collapse. Emergency asyn- chronous defibrillation is therefore required, with at least 200-J monophasic or 100-J biphasic shock. The shock should be delivered asynchronously to avoid delays related to sensing of the QRS complex. If the arrhythmia persists, repeated shocks with the maximum energy output of the defibrillator are essential to optimize the chance of successful resuscitation. Intravenous lidocaine and/or amiodarone should be administered but should not delay repeated attempts at defibrillation. # For any monomorphic wide complex rhythm that results in hemodynamic compromise, a prompt R-wave synchronous shock is required. Pharmacologic treatment to terminate monomorphic VT is not typically successful (<30%). Intravenous procainamide, lidocaine, or amiodarone can be utilized. Idiopathic LV septal VT appears to respond uniquely to IV verapamil administration. # VT in patients with structural heart disease is now almost always treated with the implantation of an ICD to manage anticipated VT recurrence. The ICD can provide rapid pacing and shock therapy to treat most VTs effectively # Several recent secondary prevention trials have demonstrated superior survival (3 years) in patients treated with ICDs versus amiodarone ALGORITHM: VF | | Assess ABC | | Give pericardial thump and begin CPR till defibrillator is ready | | Defibrillation with 200 J (2 J/kg in children) and repeat with 300 and 360 j (4 J/kg in children) | | Rhythm after first 3 shocks | | | | Asystole Normal rhythm VF still persists | | Intubate at once, obtain IV access and give adrenaline 1 mg IV and defibrillate with 360 J. | | If not aborted, repeat adrenaline in high dose and defibrillate with 360 J. | | If not aborted, give lignocaine/ bretyl ium/MgSO4/NaHCO3 with D-360 J. | | If no response, terminate efforts.
200J
250J
300J
360J