BACKGROUND/AIMS: The aim of this study was to identify changes in left ventricular (LV) performance in patients with a myocardial bridge (MB) in the left anterior descending coronary artery during resting and in an inotropic state. METHODS: Myocardial strain measurement by speckle-tracking echocardiography and conventional LV wall-motion scoring was performed in 18 patients with MB (mean age, 48.1 +/- 1.7 years, eight female) during resting and intravenous dobutamine challenge (10 and 20 microg/kg/min). RESULTS: Conventional LV wall-motion scoring was normal in all patients during resting and in an inotropic state. Peak regional circumferential strain increased dose dependently upon dobutamine challenge. Longitudinal strains of the anterior and anteroseptal segments were, however, reduced at 20 microg/kg/min and showed a dyssynchronous pattern at 20 microg/kg/min. Although there were no significant differences in radial strain and displacement of all segments at rest compared with under 10 microg/kg/min challenge, radial strain and displacement of anterior segments at 20 microg/kg/min were significantly reduced compared with posterior segments at the papillary muscle level (44.8 +/- 14.9% vs. 78.4 +/- 20.1% and 5.3 +/- 2.3 mm vs. 8.5 +/- 1.8 mm, respectively; all p < 0.001), and showed plateau (40%) or biphasic (62%) patterns. CONCLUSIONS: Reduced LV strain of patients with MB after inotropic stimulation was identified. Speckle-tracking strain echocardiography identified a LV myocardial dyssynchrony that was not demonstrated by conventional echocardiography in patients with MB.
Adrenergic beta-1 Receptor Agonists/*diagnostic use ; Adult ; Aged ; Chest Pain ; Coronary Angiography ; Diastole ; Dobutamine/*diagnostic use ; Echocardiography, Stress/instrumentation/*methods ; Female ; Humans ; Male ; Middle Aged ; *Myocardial Contraction ; *Myocardium ; Physical Exertion ; Systole ; *Ventricular Dysfunction, Left ; Ventricular Function, Left/*drug effects

BACKGROUND/AIMS: The blunted ventricular systolic and diastolic contractile responses to physical and pharmacological stress in cirrhosis are termed cirrhotic cardiomyopathy (CCM). CCM has been known to involve multiple defects in the beta-adrenergic signaling pathway. The aim of this study was to determine whether cirrhotic patients have blunted cardiac responses to catecholamine stimulation through dobutamine stress echocardiography (DSE). METHODS: Seventy-one cirrhotic patients with normal left ventricular (LV) chamber size and ejection fraction were enrolled. The LV systolic and diastolic functions were evaluated by two-dimensional and Doppler echocardiography at rest and during peak dobutamine infusion (40 microg/kg/min). An abnormal response was defined as a decrease of less than 10% in LV end-diastolic volume, a decrease of less than 20% in end-systolic volume, and an increase of less than 10% in LV ejection fraction (EF) at peak dobutamine infusion, based on previously used criteria. The early/late diastolic flow (E/A) ratio and diastolic parameters were also measured. RESULTS: A blunted LV response to dobutamine was observed in 18 of 71 cirrhotic patients (25.4%). The baseline EF was significantly higher in 18 patients with a blunted DSE response than that of those with a normal DSE response (P<0.05). The baseline and peak E/A ratios, which are common diastolic dysfunction markers, were higher in the cirrhosis group than in the control group (P<0.001). No adverse events associated with DSE were observed. CONCLUSIONS: Blunted cardiac responses to dobutamine stimulation, which are implicated in defects in the beta-adrenergic signaling pathway, might contribute to the pathogenesis of CCM in patients with cirrhosis.
Adrenergic beta-1 Receptor Agonists/*diagnostic use ; Adult ; Aged ; Dobutamine/*diagnostic use ; Echocardiography, Stress ; Female ; Heart Diseases/complications/physiopathology/*ultrasonography ; Humans ; Liver Cirrhosis/*complications/physiopathology ; Male ; Middle Aged ; Receptors, Adrenergic, beta-1/chemistry/metabolism ; Severity of Illness Index ; Ventricular Function, Left/physiology