<prompt> Cardiac conduction defect seen with Tricyclic antidepressants are due to-NE serotonin uptake inhibitorAntimuscarinic action on heaOnly NE uptake inhibitionBoth NE uptake inhibition and antimuscarinic action on hea  <response>: Ans. is d i.e., Both NE uptake inhibition and antimuscarinic action on hea o The commonest cardiovascular effect of tricyclic antidepressant overdose is sinus tachycardia, which is attributable to the inhibition of norepinephrine reuptake and the anticholinergic action. 