Influence of vessel size, age and body mass index on the flow-mediated dilatation (FMD%) of the brachial artery.

BACKGROUND: The non-invasive determination of the endothelial dysfunction (ED) of the brachial artery is a widely used method in clinical research. It remained, however, unclear, whether the test-results are influenced by the anatomical vessel size, the patients age, body mass index (BMI) or gender. METHODS: The flow-mediated vasodilatation (FMD%) of the brachial artery was determined in 122 consecutive (88 male, 34 female) patients. FMD% was measured using high resolution ultrasound (13 Mhz) at rest, during reactive hyperaemia and after the sublingual administration of glycerolnitrate (GTN%). RESULTS: Lumen diameters at rest varied from 2.48 mm to 6.33 mm (4.46+/-0.74 mm). The extent of FMD% as well as of GTN% showed an inverse correlation to the resting lumen diameters (r=-0.33, P<0.001/r=-0.51, P<0.001). This correlation was even more distinct in females (females: FMD% r=-0.54, P<0.001; GTN% r=-0.64, P<0.001 vs. males: FMD% -0.23, P<0.001; GTN% -0.59, P<0. 001). No significant influence of age (61+/-9 years, FMD%: r=-0.04, P=0.68, GTN%: r=-0.18, P=0.05) and BMI (27.03+/-3.43 kg/m(2), FMD%: r=0.16, P=0.08, GTN%: r=0.09, P=0.3) on the test results were found. CONCLUSIONS: FMD% was found to be rather independent of age or BMI. The anatomical vessel size had an influence on the test results, which was more obvious in female patients. Our data indicate the necessity of further methodological studies, in larger, community-based populations. In particular, it needs to be clarified, whether vessel size or even gender-specific correction factors are required when using this technique in routine clinical practice.

Noninvasive determination of endothelium-mediated vasodilation as a screening test for coronary artery disease: pilot study to assess the predictive value in comparison with angina pectoris, exercise electrocardiography, and myocardial perfusion imaging.

BACKGROUND: Peripheral endothelial dysfunction (ED) quantified by the determination of flow-mediated dilation (FMD%) of the brachial artery with the use of high-resolution ultrasound is an early marker of atherosclerosis. Although a positive correlation with coronary artery disease (CAD) has been reported, the unanswered clinical question is the validity of FMD% as a screening test in patients with clinical suspicion of CAD. Thus the aim of this study was to determine the predictive value of FMD% compared with angina pectoris, exercise electrocardiography, and myocardial perfusion imaging. METHODS AND RESULTS: In this pilot study, we measured ED in 122 patients scheduled for coronary angiography by using high-resolution ultrasound (13 MHz). We defined ED as FMD%

[The ultrasonic measurement of the endothelial function of the brachial artery in suspected coronary heart disease]. / Ultraschallmessung der Endothelfunktion der Arteria brachialis bei Verdacht auf eine koronare Herzkrankheit.

BACKGROUND AND OBJECTIVE: A positive correlation between the presence of coronary artery disease (CAD) and peripheral endothelial dysfunction (ED) of the brachial artery has been shown in several studies. Aim of the present study was to evaluate whether the non-invasive determination of ED could also be used as a screening test in patients suspected of having CAD. PATIENTS AND METHODS: 122 patients were included. 112 had an exercise-ECG before hospital admission. Preceding coronary angiography, FMD% was measured by high-resolution ultrasound (13 Mhz). Longitudinal scans of the brachial artery were done at rest, during reactive hyperemia and after the sublingual administration of nitroglycerin. RESULTS: In 101 of the 122 patients the presence of CAD was diagnosed by angiography, whereas 21 patients had normal coronary arteries. The extent of the vasodilation (FMD%) was found to be largely independent of the resting vessel diameters (FMD%/vessel diameter at rest: r = -0.32767 p = 0.0002). FMD% was significantly higher in patient without CAD than in the CAD group (7.01 +/- 3.5% vs. 3.73 +/- 4.11%, p < 0.001). Comparison of sensitivity and specificity to predict the presence of CAD between FMD% [sensitivity 71.3%, specificity 81%] and exercise-ECG [sensitivity 82.4%, specificity 57.1%] gave similar results. No correlation was found between the degree of the impairment of FMD% and the severely of CAD. CONCLUSION: The determination of peripheral ED was found to be a sensitive and specific measure for predicting the presence of CAD in our cohort. Since this approach is non-invasive, non-radioactive and cost-effective it warrants further evaluation of its role as an additional screening test in patients clinically suspected of having CAD.

Comparison of peripheral endothelial dysfunction and intimal media thickness in patients with suspected coronary artery disease.

OBJECTIVE: Flow associated dilatation (FAD%) and intimal media thickness are established markers of early atherosclerosis. This study aimed to compare the ability of the non-invasive measurements FAD% and intimal media thickness to predict coronary artery disease. METHODS: FAD% and intimal media thickness were determined using high resolution ultrasound in 122 patients with clinically suspected coronary artery disease before coronary angiography. Results are given as mean (SD). RESULTS: Patients with coronary artery disease had reduced FAD% compared with those with angiographically normal coronary vessels (3.7 (4.1) v 7.0 (3.5)%, p < 0.001), whereas intimal media thickness tended to be increased in patients with coronary artery disease (0.58 (0.35) v 0.47 (0.11)mm, p = 0.054). There was a negative correlation between FAD% and intimal media thickness (R = -0.317, p = 0.0004). Receiver operating characteristic analysis showed that FAD% < or = 4.5% predicted coronary artery disease with a sensitivity of 0.71 (95% confidence interval 0.61 to 0.80) and a specificity of 0.81 (0.58 to 0.95). In contrast, intimal media thickness showed a positive correlation with the extent of coronary artery disease (number of vessels with a lesion > or = 50%) (R = 0.324, p = 0.0003), without a clear cut off point. CONCLUSIONS: In patients with clinically suspected coronary artery disease, FAD% discriminates between the presence or absence of coronary artery disease, whereas intimal media thickness is associated more with the extent of coronary artery disease.