Lidocaine arrhythmia prevention

Aprindine ( ) is a new anti-arrhythmic agent that is 20 times more potent than lidocaine as a local anesthetic. Clinical studies have shown that aprindine is a long-acting, orally effective anti-arrhythmic agent which compares favorably with intravenous lidocaine in preventing ventricular arrhythmias after acute myocardial infarction.43... 

Early after-depolarizations and the associated ventricular arrhythmia can be prevented or suppressed by the appropriate adjustment of plasma potassium and/or magnesium concentrations. Lidocaine or procainamide may be effective for termination of the arrhythmia. 

Lidocaine is the agent of choice for termination of ventricular tachycardia and prevention of ventricular fibrillation after cardioversion in the setting of acute ischemia. However, routine prophylactic use of lidocaine in this setting may actually increase total mortality, possibly by increasing the incidence of asystole, and is not the standard of care. Most physicians administer IV lidocaine only to patients with arrhythmias. 

MI usually develops after rupture or erosion of an atherosclerotic plaque within a coronary blood vessel. At this site, the clotting cascade is activated and the resultant thrombus occludes the lumen. In all patients under suspicion of MI, immediate therapy has to be initiated by the emergency physician. To relieve the patient from severe pain and anxiety, morphine and a benzodiazepine need to be given. Antiplatelet drugs and heparin are necessary for preventing further formation of thrombi. Nitroglycerin can be used to reduce cardiac load. When blood pressure and heart rate have stabilized, a p-blocker can be administered to lower cardiac 02 consumption and the risk of arrhythmias. Infusion of lidocaine is required to counter the threat of arrhythmias. The chance of survival of the MI patient depends on the interval between the onset of infarction and the start of therapy. 

All basic and advanced life-support measures should be implemented. Gastric decontamination should be performed. Butyrophenones are readily absorbed by activated charcoal. Aggressive supportive care should be instituted. Dystonic reactions respond well to intravenous benztropine or diphenhydramine. Oral therapy with diphenhydramine or benztropine should be continued for 2 days to prevent recurrence of the dystonic reaction. For patients suffering from neuroleptic malignant syndrome, a potentially fatal condition associated with the administration of antipsychotic drugs, dantrolene sodium, and bromocriptine have been used in conjunction with cooling and other supportive measures. Arrhythmias should be treated with lidocaine or phenytoin. Diazepam is the drug of choice for seizures phenytoin is used to prevent recurrence. Hemodialysis and hemoperfu-sion have not been shown to be effective. 

Lidocaine, proprietary name Xyhcaine, is the drug of choice for the initial therapy of PVCs and the prevention of ventricular arrhythmias. Lidocaine is contraindicated when bradycardias and severe atrioventricular node block appear after myocardial infarction. Lidocaine shortens the action potential refractory period in these fibers and does so at concentrations less than those required to exert pharmacological effects at other sites, such as the ventricular myocardium. 

Lidocaine as a preventive ( ) this point is highly debatable, since arrhythmia can be avoided simply by taking more than 1 hour to apply the phenol. Simple lidocaine used to do nerve blocks before the phenol peel should be considered a cautious technique. 

Lidocaine is ineffective orally and its use is restricted to preventing and treating ventricular arrhythmia after myocardial infarction. (Lidocaine by virtue of the same mechanism of action is used as a local anaesthetic. See Chapter 12.)... 

Lidocaine [2-(diethylamino)-N-(2, 6-dimethylphenyl) acetamide monohydrochloride] is the most commonly used amino amide-type local anesthetic. Lidocaine is very lipid soluble and, thus, has a more rapid onset and a longer duration of action than most amino ester-type local anesthetics, such as procaine and tetracaine. It can be administered parenterally (with or without epinephrine) or topically either by itself or in combination with prilocaine or etidocaine as a eutectic mixture that is very popular with pediatric patients. The use of lidocaine-epinephrine mixtures should be avoided, however, in areas with limited vascular supply to prevent tissue necrosis. Lidocaine also frequently is used as a class IB antiarrhythmic agent for the treatment of ventricular arrhythmias, both because it binds and inhibits sodium channels in the cardiac muscle and because of its longer duration of action than amino ester-type local anesthetics. 

TLC is useful for monitoring drugs used in the treatment of cardiac disorders. Drugs such as lidocaine and digitalis and its derivatives are used to regulate heartbeat, thus preventing cardiac arrhythmias. Malikin et al. (1984) have reported on the use of HPTLC to monitor the serum of patients treated with various drugs used to control cardiac arrhythmias. 

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