-Severe Aortic Stenosis
                         -Atrial tachyarrhythmias with uncontrolled ventricular response
                         -Recent MI (<1 week)
                         -Unstable Angina
                         -Prior h/o VT
                         -Uncontrolled HTN (BP > 200/110)
                         -Aortic dissection or large aortic aneurysm
     -Beta-blockers will attenuate HR response

Same criteria for stopping as exercise stress test:

Mechanism of action direct Beta 1 and 2 stimulation with dose related increase in HR, BP, and
myocardial contractility. Dobutamine increases regional myocardial blood flow based on physiological
principles of coronary flow reserve. A similar dose-related increase in subepicardial and subendocardial
blood flow occurs within vascular beds supplied by normal coronary arteries. However, blood flow
increases minimally within vascular beds supplied by significantly stenoses arteries, with most of the
increase occurring in the subepicardium rather than the subendocardium.
at a dose of  20 mck/kg/min, dobutamine induced coronary flow heterogeneity is similar
to exercise but less than that induced by adenosine or dipyridamole.

Side Effects
-75% of patients develop side effects: Palpitations 29% - Chest Pain 31% - Headache 14% -
Flushing 14% - Dyspnea 14% - SVT or Ventricular arrhythmias 8%
-Ischemic ST depression occurs in ~ 1/3 of patients
-Severe side effects may require reversal with short acting beta-blocker:
 Esmolol 0.5 mg/kg over 1'

Dosage starting at 5-10 mcg/kg/min, increased at 3-minute intervals to 20, 30, and 40
mcg/kg/min. Half-Life is ~2 min. As with exercise, goal is to achieve >85% of MAAP-HR

Single vessel disease = 40-92%
Multi vessel disease = 65-83%
beta-blocker injection at peak stress increases sensitivity from 81 to 99% for single vessel
In a 200 patient study, BB injection converted 3 patients from single vessel dz to multi vx and 1 patient from
normal to multi vessel disease (multiple WMAs)

other numbers:
S 81% single vessel disease
S 85% multi vessel vessel
During recovery sensitivity increases to 97%
(single vessel dz 98% - multi vx dz 89%)

At recovery: rate-pressure product (measurement of oxygen consumption rate) was lower than at peak
stress and higher than at rest = prolonged ischemic effect of dobutamine during recovery phase

-Low dose stages: permits recognition of viability and ischemia in segments with abnormal function

Side effect reversal: beta-blockers

Our Lab's criteria for stopping
Target HR
Severe WMAs
Downsloping ST depressions >2mm (0.2 mV) measured 80 ms after the J point
ST elevations >2 mm in the absence of Q waves
Symptomatic decrease in SBP> 40 mmHg or SBP<90
HTN (>240/140)
Sustained arrhythmias
Severe Angina
Intolerable side effects

Recovery = within 10% range of resting HR
5-10 mcg/kg/min increased every 3' to
20, 30 , and
40 mcg/kg/min to achieve
85% of MAAP-HR - atropine 0.25-0.5
Esmolol 0.5 mg/kg over 1'