Lignocaine ventricular tachycardia

Mrs. Chen is 68 and has suffered a myocardial infarction. An ECG showed ventricular tachycardia, she was successfully defibrillated and now, to maintain sinus rhythm, your consultant asks you to load her with lignocaine. She weighs 85 kg and the Cp he wants you to achieve is 1.5 mg/1. You lookup the Vd... 

These are common after myocardial infarction. Their particular significance is that the R-wave (ECG) of an ectopic beat, developing during the early or peak phases of the T-wave of a normal beat, may precipitate ventricular tachycardia or fibrillation (the R-on-T phenomenon). About 80% of patients with myocardial infarction who proceed to ventricular fibrillation have preceding ventricular premature beats. Lignocaine (lidocaine) is effective in suppression of ectopic ventricular beats but is not often used as its addition increases overall risk. 

Class I (which has a number of subtypes) is mainly used to treat atrial and ventricular tachycardias, and contains a number of sodium-channel BLOCKERS, e.g. disopyramide, flecainide. lignocaine. procainamide and quinidine. 

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