lexiscan Flashcards
lexiscan dose
5mL (0.4mg)
what are the 4 types of adenosine receptors
A1, A2A, A2B, A3
where are adenosine receptor located
located in various tissues through the body (AV node, pulmonary, periphreal vessels, coronary vessels)
what is the A2A receptor responsible for
mediates coronary vasodilation (peak effect ~30 sec after inj)
what is the potency of the agonist determined by
affinity for its receptor
high affinity=
binds readily and remains bound (prolonged response)
low affinity=
bind less tightly and disassociates quickly (physiological response terminates quickly)
duration for low affinity
short
duration for high affinity
long
lexiscan has a ____affinity for ________ ______ ______
low, adenosine receptor agonist
coronary arteris have a high densisty of____ which causes_____
A2A receptors and only need to activate a fraction of them to reach max coronary vasodilation
what is the chemical structure of lexiscan
modified form of adenosine molecule w/ additional side chain
A2B ad A3 are responssible for
bronchoconstriction, a major issue seen with adenosine use
lexi effects the A2A adenosine receptor agonist w/o activating other three receptors
which is good
A2A receptor =
reduction in chest pain and nausea side effetc and slight inc in SOB
symptoms start to dissipate about
5-15 min after
3 T1/2 of lexi
intial phase=2-4 min
intermediate phase=30 min
terminal phase=2 hrs
low level exercise can be done w lexi which includes benefits such as
help we decrease in side effects, clear GI uptake for better image quality, quicker imaging
inj regadenoson over how many sec
10 sec
inj saline over how many sec
same pace as reg- 10 sec
inj radiotracer how many sec after flush
10-20 sec
side effetcs of regadenoson
headache, dyspnea, flushing, chest pain/discomfort, nausea./abd discomfort, rhytym abnormality
what is common to see after reg inj
modest HR incr and decr in BP
contraindications to reg
same as adenosine
headache is only symptom that take a little longer to rid
30 min
how much aminophylline can be given
50-250 mg
how long do you have to wait to give aminophylline
at least 1 min after reg inj
what more serious events have been reported with aminophylline use
stroke, MI, ischemia, A-fib, A-flutter, seizures
steps for a walking lexi
-12 series EKG (limbs, supine, standing)
-10-20 sec of walking at 0.8 mph (warm up)
- once pt comfy inject reg
-walk at 1 mph
-10-20 sec later inj regadenoson
-EKG monitored for 4 min
