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Normal changes in left ventricular filling and hemodynamics during dobutamine stress echocardiography
M Tanimoto1, R G Pai, W Jintapakorn
1Section of Cardiology, Jerry L. Pettis Veterans Administration Hospital, Loma Linda, CA 92357, USA.
Insights
High-dose dobutamine infusion increases cardiac output and decreases vascular resistance, often causing left ventricular cavity obliteration. Isovolumic relaxation time changes during dobutamine stress echocardiography may indicate early myocardial ischemia.
Area of Science:
- Cardiology
- Echocardiography
- Pharmacology
Background:
- Dobutamine stress echocardiography (DSE) is widely used for diagnosing myocardial ischemia.
- Hypotension is a potential side effect during DSE, and its mechanism requires further elucidation.
Purpose of the Study:
- To investigate the hemodynamic and diastolic effects of high-dose dobutamine infusion.
- To explore the potential of diastolic parameters, specifically isovolumic relaxation time, as indicators of myocardial ischemia during DSE.
Main Methods:
- Dobutamine infusion at high doses was administered.
- Echocardiographic parameters including cardiac output, systemic vascular resistance, left ventricular size, and diastolic velocities (mitral A wave, E/A ratio) were assessed.
- Isovolumic relaxation time (IVRT) and rate-corrected IVRT were measured.
Main Results:
- High-dose dobutamine caused a dose-dependent increase in cardiac output and decrease in systemic vascular resistance.
- Significant reductions in left ventricular size and E/A velocity ratio, along with an increase in mitral A wave velocity, were observed.
- A reduction in IVRT was noted, while rate-corrected IVRT remained largely unchanged. Left ventricular cavity obliteration was common.
Conclusions:
- High-dose dobutamine significantly alters cardiac hemodynamics and left ventricular diastolic function.
- The observed changes, particularly alterations in IVRT, may contribute to hypotension during DSE.
- Further research is warranted to confirm if IVRT during DSE can serve as an early marker for myocardial ischemia.
Abstract:
During high-dose dobutamine infusion, there is a dose-dependent increase in cardiac output, a reduction in systemic vascular resistance, a reduction in left ventricular size, an increase in the mitral A wave velocity, a reduction in the E/A velocity ratio, and a reduction in the isovolumic relaxation time, with little change in the rate-corrected isovolumic relaxation time. Left ventricular cavity obliteration is common. This information may be useful in defining the mechanism of hypotension commonly seen during dobutamine stress echocardiography. It is speculated that the diastolic behavior of the left ventricle during dobutamine stress echocardiography, especially the isovolumic relaxation time, may provide an additional indicator of early myocardial ischemia, but this needs to be confirmed by larger independent studies.