Abstract
Purpose: To elucidate whether myocardial blood volume is associated with resting left ventricular (LV) function and/or contractile reserve in patients with dilated cardiomyopathy (DCM) using myocardial contrast echocardiography (MCE). Subjects and Methods: Twenty-one patients with DCM who had LV ejection fraction (LVEF)⟨45% were enrolled. Under continuous infusion of Levovist, harmonic power Doppler images were acquired at end systole every 6th beat using the apical two- and four-chamber views. Dividing the LV wall into six myocardial segments, myocardial contrast intensity (CImyo) and the contrast intensity of the adjacent intracavity blood pool (CIblood) were measured. Relative CI (RelCI), calculated as CImyo-CIblood [dB], logarithmically represents the ratio of microbubble concentrations between the myocardium and blood pool. Myocardial blood volume can be derived as 10(RelCI/10)×100 [%]. Dobutamine stress echocardiography (up to 20 μg/kg/min) was performed, and LVEF was measured at baseline and at peak dose. Results and Discussion: Myocardial blood volume did not correlate with any parameters of resting LV function, but it significantly correlated with percent change in LVEF during dobutamine stress echocardiography (r0.54, p0.01). Myocardial histomorphometric features in patients with DCM conceivably cause the reduction in myocardial blood volume, being related to the depressed contractile reserve. Conclusion: Myocardial blood volume measured by MCE was associated with LV contractile reserve in patients with DCM.
