The cardiovascular system is more resistant than the central nervous system to local anaesthetic toxicity.

Usually, about 4-7 times the convulsant dose needs to be injected before cardiovascular collapse occurs.

Altered cardiac conduction can cause arrhythmias.

Cardiovascular collapse is due to the depressant effect of the LA drug acting directly on the myocardium.

Bupivacaine is more cardiotoxic than lidocaine.

Severe and intractable arrhythmias can occur with accidental IV injection of bupivacaine.