vt is characterized by : a ) qrs wider than 0.14 sec. , b ) left axis deviation ( a and b criteria are no longer reliable when a preexisting bundle branch block is present ) , c ) mono or biphasic v1 configuration ( biphasic rsr ' in st ) , d ) multiformity , e ) a-v ratio different from 1:1 in spontaneous conditions or during vagal or pharmacological ( atp , verapamil ) stimulation , f ) presence of fusion or capture beats .
C0039240
st
C0042523
verapamil