[Show abstract][Hide abstract] ABSTRACT: Based on findings of experimental models of diabetes mellitus (DM) showing increased expression of vascular cyclooxygenase-2 (COX-2), we hypothesized that in patients with DM changes in COX-2-dependent prostaglandin synthesis affect vasomotor responses of coronary arterioles. Arterioles were dissected from the right atrial appendages obtained at the time of cardiac surgery of patient with DM(+) or without documented diabetes DM(-). Isolated arterioles (89+/-15 microm in diameter) were cannulated and pressurized (at 80 mm Hg), and changes in diameter were measured with video microscopy. After spontaneous tone developed [DM(-): 32+/-7%; DM(+): 37+/-5%; P=NS], arteriolar responses to bradykinin were investigated. Dilations to bradykinin (0.1 nmol/L to 1 micromol/L) were significantly (P<0.05) greater in DM(+) than DM(-) patients (10 nmol/L: 77+/-10% versus 38+/-14%). In both groups, dilations were similar to the NO-donor, sodium nitroprusside. In arterioles of DM(+), but not those of DM(-), patients' bradykinin-induced dilations were reduced by the nonselective COX inhibitor indomethacin or by the selective COX-2 inhibitor NS-398 (DM(+) at 10 nmol/L: to 20+/-4% and 29+/-7%, respectively). Correspondingly, a marked COX-2 immunostaining was detected in coronary arterioles of DM(+), but not in those of DM(-) patients. We conclude that in coronary arterioles of diabetic patients bradykinin induces enhanced COX-2-derived prostaglandin-mediated dilation. These findings are the first to show that in humans diabetes mellitus increases COX-2 expression and dilator prostaglandin synthesis in coronary arterioles, which may serve to increase dilator capacity and maintain adequate perfusion of cardiac tissues.
Circulation Research 09/2006; 99(5):e12-7. DOI:10.1161/01.RES.0000241051.83067.62 · 11.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The PET technique has been available for myocardial viability studies in Hungary since 1994. The early comparative results showed that FDG-PET identified more potentially reversible myocardial damages than [201Tl]-scintigraphy, defining the viability either by preserved metabolic activity of 50% or by metabolism-perfusion mismatch. According to the follow up of revascularized patients in our cases, FDG-PET had a positive predictive value for functional recovery at 80%. In our opinion, it is the detection of glucose metabolism that predicts with the greatest accuracy segments of hibernating myocardial tissue that will recover after revascularization. Unlike dobutamine echocardiography, PET can detect viable ventricular segments in the myocardium of lost contractile material often seen in the histological studies of chronically ischemic myocardium. The FDG-PET method can be regarded as the gold standard of myocardial viability.
[Show abstract][Hide abstract] ABSTRACT: Detection of left ventricular contractile reserve by means of dobutamine stress echocardiography is a well known technique. The aim of the present study was to detect velocity changes during the administration of dobutamine, to establish if Doppler myocardial imaging is a suitable method for determining left ventricular contractile reserve, and to determine if the technique provides more information than traditional stress echocardiography. Twenty-five patients (all males; mean age, 53.4 years) were examined for a clinical diagnosis of idiopathic dilated cardiomyopathy with a poor left ventricular systolic function (ejection fraction less than 30%). Doses of 5-10 and 20 mg/kg/min dobutamine were administered and elevated at 4-minute intervals. Ejection fraction was calculated using the Simpson rule. The peak systolic and the early and late diastolic velocities were measured in the basal segment of the septum and the inferior wall at baseline and at full dose of dobutamine. Results indicated that peak systolic velocity increased significantly, both in the septum (0.11±0.03 vs. 0.20±0.05 m/sec; p=0.001) and in the inferior wall (0.10±0.05 vs. 0.17±0.06 m/sec; p=0.03). Late diastolic velocities also increased significantly, both in the septum (0.17±0.05 vs. 0.22±0.07 m/sec; p=0.01) and in the inferior wall (0.18±0.08 vs.0.21±0.02 m/sec; p=0.01). There was a significant linear correlation between the relative increases in basal ejection fraction value and in peak systolic velocity upon dobutamine stimulation. Patients were divided into responders and nonresponders based on responses in either ejection fraction (25% relative increase) or peak systolic velocity (5 cm/s increase). This study concludes that 1) Doppler myocardial imaging is an adequate and simple technique to examine left ventricular contractile reserve; and 2) measurement of peak systolic velocity during dobutamine stimulation seems to be a simple and good indicator of left ventricular contractile reserve. (c)2001 CHF, Inc.
[Show abstract][Hide abstract] ABSTRACT: Left ventricular aneurysm had detected at the 55-year-old woman after extensive anterior myocardial infarction in association with progressive ventricular dilatation and symptoms of heart failure. Coronary angiogram revealed a serious lesion in the proximal segment of the left anterior descending coronary branch with a poor run off tract. 18FDG-PET and 99mTc-MIBI-SPECT investigation were performed in order to differentiate the scarred regions from the viable myocardial segments. Taking into consideration the results an aneurysm resection was performed without revascularisation procedure. After the surgery not only the ejection fraction and the left ventricular dilatation had improved but the tissue perfusion in the segments surrounding the resected aneurysm had also showed a significant increase at the follow up MIBI-SPECT imaging.