Most cardiotoxic local anesthetic is:
Correct Answer: Bupivacaine
Description: Ref: L Mather LE, Chang DM. Cardiotoxicity with modem local anaesthetics: is there a safer choice ? Drugs. 2001;61(3):333-42. 2. Lied jam JJ. de la Coassay e JE, Bassoul B. Brugada J.Mechanisms of the cardiac toxicity of bupivacaine. Ann Fr Anesth Reanim. 1988; 7(3):204-10Explanation:Bupivacaine is the most cardiotoxic of all the local anaesthetics.Associated with sudden increase in the plasma concentration of bupivacaine.It involves both electrical and mechanical structures within the heart.The main site of action on cardiac conduction tissue is the Vmax of phase 0 of the action potential of fast-reacting structures tlNa current).Bupivacaine, like lidocaine and the other class I antiarrhythmic drugs, blocks the sodium channels, this block being more slowly reversible.The disturbance of sodium channels throughout the heart leads to a decreased conduction speed throughout the conduction system, thus explaining possible acute conduction disturbances originating below the bundle of His.The ventricular dysarrhythmias are due to a re-entry circuit secondary to a slowing in conduction speed.The sinus bradycardias and junctional disturbances seen in toxic accidents are probably due to an inhibition of the slow current of the atrial and atrio-ventricular nodes (Isi current!.Bupivacaine, at toxic levels, has a direct effect on contractility.The negative inotropic effects seem to be due to a fall in the intracytoplasmic calcium concentration on wrhich depends the excitation- contraction couple, as well as disturbed cellular energetic events dependent on the contraction.Bupivacaine is disproportionately more cardiotoxic than its shorter-acting counterparts like ropivacaine and levobupivacaine.While all local anaesthetics can cause direct negative inotropic effects, ropivacaine and levobupivacaine are less cardiotoxic than bupivacaine.
Category:
Anaesthesia
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