CORRESPONDENCE
Reply
Francesco Barillà, MDa
a Second Section of Cardiology, University of Rome "La Sapienza", Policlinico Umberto I, Viale del Policlinico, 155, 00161 Rome, Italy
We are grateful to Dr. Barletta for his comments. Obviously, the findings we have reported constitute an intermediate step of a biphasic response phenomenon, as stated by Dr. Barletta. However, a 5-min step protocol for low dose dobutamine echocardiography is common (1,2), and a biphasic response (i.e., wall motion improvement followed by worsening) is rarely observed at low doses of 5 to 10 µg/kg body weight per min (3). Nevertheless, no change in wall motion and thickening occurred during the 3 min after tracer injection, even when we used 10 µg/kg per min of dobutamine.
We also wish to emphasize that our study was not intended to describe the behavior of inotropic contractile reserve during low dose dobutamine infusion, but it was aimed at investigating the pathophysiologic and clinical implications of the presumed mismatch between perfusion and contractility in areas with severely hypoperfused viable myocardium.
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References
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- Barillà F, Gheorghiade M, Alam M, Khaja F, Goldstein S. Low-dose dobutamine in patients with acute myocardial infarction identifies viable but not contractile myocardium and predicts the magnitude of improvement in wall motion abnormalities in response to coronary revascularization. Am Heart J. 1991;122:1522–1531[CrossRef][Medline]
- Panza JA, Dilsizian V, Laurienzo JM, Curiel RV, Katsiyiannis PT. Relation between thallium uptake and contractile response to dobutamine: implications regarding myocardial viability in patients with chronic coronary artery disease and left ventricular dysfunction. Ciculation. 1995;91:990–998
- Afridi I, Kleiman NS, Raizner AE, Zoghbi WA. Dobutamine echocardiography in myocardial hibernation: optimal dose and accuracy in predicting recovery of ventricular function after coronary angioplasty. Circulation. 1995;91:663–670[Abstract/Free Full Text]
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