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Comparative haemodynamic effects of dobutamine and isoproterenol in man
Insights
Dobutamine significantly increases cardiac output and left ventricular function in patients with heart failure. This potent inotropic drug shows mild effects on heart rate and vascular resistance, making it valuable for managing severe heart failure.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Congestive heart failure (CHF) is a complex condition characterized by impaired cardiac function.
- Effective management of CHF requires inotropic agents to improve myocardial contractility.
Purpose of the Study:
- To evaluate the hemodynamic effects of dobutamine in patients with and without congestive heart failure.
- To compare dobutamine's effects with isoproterenol, another inotropic agent.
Main Methods:
- Dobutamine was infused at 8 mcg/kg/min in 17 patients.
- Hemodynamic parameters including cardiac output, mean aortic pressure, heart rate, and left ventricular pressures were measured.
- Comparison with equi-inotropic doses of isoproterenol in 10 patients.
Main Results:
- Dobutamine increased cardiac output (2.92 to 4.45 L/min/m²) and peak left ventricular dp/dt (doubled).
- Left ventricular end-diastolic pressure decreased, while mean aortic pressure and heart rate showed minimal changes.
- Dobutamine demonstrated potent inotropic effects with less impact on heart rate and vascular resistance compared to isoproterenol.
Conclusions:
- Dobutamine is a potent inotropic agent with beneficial effects on cardiac output and contractility.
- Its mild chronotropic and peripheral vascular effects suggest potential value in managing severe heart failure, particularly when hypotension is not a primary concern.
Abstract:
Dobutamine was infused at a rate of 8 mcg/kg/min in 17 patients with or without congestive heart failure. Cardiac output increased from an average 2.92 to 4.45 1/min/m2(p less than 0.001) with no change in mean aortic pressure (93.4 to 97.8 mmHg) and only a slight increase in heart rate (78 to 87 beats/min). Left ventricular end-diastolic pressure decreased from an average 19 to 13.7 mmHg (p less than 0.01). Peak left ventricular dp/dt was doubled (1147 to 2370 mmHg/sec, p less than 0.001) and Vmax increased from 1.08 to 2.18 circ/sec (p less than 0.001). In 10 patients given equi-inotropic doses (100 per cent increase in peak dp/dt) Isoproterenol produced a greater increase in cardiac output (71 percent) than Dobutamine /51 percent). Isoproterenol caused mean aortic pressure to fall significantly (8 percent) while no change was noted with Dobutamine. Accordingly, peripheral vascular resistances were reduced to a greater extent with Isoproterenol than with Dobutamine (p less than 0.05). Mean pulmonary arterial pressure decreased significantly (25 +/- 5.9 to 22 +/- 5.7 mmHg, p less than 0.05) with Isoproterenol infusion and remained unchanged with Dobutamine infusion. Dobutamine increased both stroke work (57 percent) and minute work (83 percent). With Isoproterenol however, only minute work was significantly increased (90 percent). Dobutamine therefore is a potent inotropic drug, with mild chronotropic and peripheral vascular effect and may be valuable in the management of severe heart failure not associated with hypotension.