Dobutamine is a synthetic catecholamine which has significant inotropic effect and less chronotropic effect.
It has predominantly b1 activity with weak b2 and a1 activity.
It increases heart rate and contractility with a resultant increase in cardiac output.
The onset of action is approximately 2 minutes and the half life is 2 minutes. It is renally and hepatically excreted.
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Contraindications
Contraindications (as with exercise PLUS):
- Left bundle branch block (LBBB)
- Bifascicular block
- Paced rhythm
Protocol
- There is no universal protocol although many departments in the UK use an infusion starting at 5-10mg/kg/min and increase this by 5-10mg/kg/min to a maximum of 40mg/kg/min
- The infusion is continued until the target heart rate is achieved and the radiopharmaceutical then injected. Ideally the infusion should then continue for a further 2 minutes
Patient preparation
- Withold b blockers for 48 hours (as they reduce the inotropic and chronotropic effect)
- Ideally also stop calcium channel blockers for 24 hours.
Side effects
- Chest pain 31%
- Premature ventricular contractions 15%
- Dyspnoea 14%
- Nausea 8%
- Premature atrial contractions 8%
- Anxiety 6%
- Headache 4%
- Hypo/hypertension 4%
When to stop the test
When to stop the test (as for exercise test)
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