40-year old woman presents with sudden onset palpitations. An ECG done reveals narrow QRS complex tachycardia. The most likely diagnosis is:
(a) Ventricular tachycardia
(b) Pre-excited tachycardia
(c) Paroxysmal supraventricular tachycardia with aberrancy
(d) AV re entry tachycardia
AVNRT is another form of PSVT only In SVT with aberrancy: impulse come down normally till just below AVN and then there is some obstruction to the conduction such as RBBB or LBBB, but it manages to go down via some rapid pathway (like left bundle in RBBB or right bundle in LBBB). So The initial part of the QRS is narrow but the latter part of the QRS becomes slow and wide so it is no more a narrow Qrs tachycardia