Mechanism
of action
|
T
1/2
|
Administration
|
Side
effects
|
Contraindications
|
|
Adenosine
|
A2A
receptor à direct
coronary vasodilation à 3.5- 4 x
increased blood flow à stenotic
epicardial coronaries will have attenuated hyperemic response.
True
ischemia may be induced by coronary steal phenomenon.
|
Secs
|
140
mcg/kg/min over a 6 min period
Minimum
time to tracer injection: 2 mins
Continue
infusion for 2 mins after tracer injection
|
Nonspecific
chest pain: not an indicator of CAD
ST
depression >1mm: indicative of significant CAD
A1
receptor: AV block à does not
require termination of infusion
A2b
receptor: Hypotension
A2b
and A3 receptors: Bronchospasm
Resolve
in few seconds (due to extremely short half-life of adenosine)
|
Asthma
with ongoing wheezing
2/3
AV block without a pacemaker
SBP
<90 mmHg
Use
of dipyridamole in last 48 hours; aminophylline in 24 hours or caffeine in
last 12 hours (pentoxifylline OK)
ACS
|
Regadenoson
|
A2A
receptor à direct
coronary vasodilation (lower affinity than adenosine)
|
2-4
mins
|
0.4mg/10
ml given as rapid injection followed by saline flush
Tracer
injection 10-20 secs after
|
SOB,
flushing, headache
Most
resolve within 15 mins, headaches resolve in 30 mins
(Use
aminophylline 50-250 mcg infused slowly)
Hypotensionѱ
|
Asthma
with ongoing wheezing
2/3
AV block without a pacemaker
SBP
<90 mmHg
Use
of dipyridamole in last 48 hours; aminophylline in 24 hours or caffeine in
last 12 hours (pentoxifylline OK)
ACS
|
Dipyridamole
|
Prevents
reuptake and deamination of adenosine à indirect coronary vasodilator
Dipyridamole
induced hyperemia lasts more than 15mins
|
30-45
mins
(liver)
|
0.56mg/kg
IV over 4 mins (142mcg/kg/min)
Tracer
injection after 3-5 mins
|
Flushing,
chest pain, headaches, dizziness.
Resolve
in 15-25 mins
(Use
aminophylline 125-250 mcg infused slowly- should also be used in the presence
of ischemic changes after dipyridamole)
|
Same
as adenosine.
CAN
be used in patients taking oral dipyridamole.
|
Dobutamine
|
Direct
B1 and B2 stimulation
Increase
in heart rate, blood pressure and myocardial contractility.
Increases
regional myocardial blood flow (similar to exercise, less than adenosine).
Does
not increase venous return (no increase in wall stress)
|
2
mins
|
5mcg/kg/min
increased at 3 minute intervals to 40mcg/kg/min. Tracer injection at peak
dose and continue infusion for 2 mins after
|
Palpitations,
chest pain, headache, flushing, dyspnea
(Use
esmolol 0.5mg/kg over 1 min)
|
ACS
Hemodynamically
significant LVOT obstruction
Severe
AS
Prior
h/o VT
Aortic
dissection/large aortic aneurysm
Uncontrolled
hypertension
B
blockers
|
Ѱ
Risk of hypotension higher in patients with autonomic dysfunction, hypovolemia,
left main coronary artery stenosis, stenotic valvular heart disease,
pericarditis, pericardial effusions, stenotic carotid artery disease with
cerebrovascular insufficiency