Blood flow pattern in the middle cerebral artery in relation to indices of arterial stiffness in the systemic circulation.

BACKGROUND: The brain is perfused at high-volume flow throughout systole and diastole. We explored the association of blood flow in the middle cerebral artery (MCA) with the pulsatile components of blood pressure in the systemic circulation and indices of arterial stiffness. METHODS: We enrolled 334 untreated subjects (mean age, 50.9 years; 45.4% women) who had been referred for ambulatory blood pressure monitoring to Ruijin Hospital, Shanghai, China. We measured the MCA pulsatility index (PI) by transcranial Doppler ultrasonography. The indices of arterial stiffness included pulse pressure (brachial (bPP) and central (cPP) measured at the office and 24-h ambulatory (24-h PP)) and carotid-femoral (cf-PWV) and brachial-ankle (ba-PWV) pulse wave velocity. Effect sizes, expressed per 1 s.d., were adjusted for sex, age, heart rate, and mean pressure. RESULTS: Women had faster MCA blood flow than men (68.0 vs. 58.3 cm/s), but lower PI (75.4 vs. 82.3%; P < 0.001). The five arterial stiffness indices were intercorrelated (r ≥ 0.37; P < 0.001). PI increased (P ≤ 0.045) with bPP (+6.78%), cPP (+5.56%), 24-h PP (+7.58%), cf-PWV (+1.59%), and ba-PWV (+3.46%). In explaining PI variance, bPP ranked first (partial r(2) = 0.25), 24-h PP second (0.20) and cPP third (0.14). In models including both cf-PWV and ba-PWV, only the latter was significant (-0.19%; P = 0.84 vs. +3.54%; P < 0.001). In models including both bPP and ba-PWV, only the former contributed to PI variance (+6.98%; P < 0.001 vs. -0.24%; P = 0.78). CONCLUSION: MCA blood flow is closely associated with the pulsatile pressure in the systemic circulation, which depends on arterial stiffness as measured by PWV.

Validation of the noninvasive assessment of central blood pressure by the SphygmoCor and Omron devices against the invasive catheter measurement.

BACKGROUND: To investigate the accuracy of the SphygmoCor and Omron HEM9000-AI devices in the estimation of central blood pressure (BP) in comparison with the simultaneous invasive catheter measurement. METHODS: The radial arterial pulse was sequentially recorded by the use of the Omron and SphygmoCor devices in 33 patients, with the calibration of the brachial oscillometric BP, to derive central BPs, which were also measured simultaneously with a catheter-based fluid-filled manometer system. The procedure was repeated three times to obtain 99 pairs of noninvasive and invasive measurements. RESULTS: The noninvasive central systolic BP estimations were significantly (P < 0.001) associated with the invasive measurement at the ascending aorta, with a correlation coefficient of 0.91 and 0.90 for the SphygmoCor and Omron devices, respectively. However, both devices underestimated central systolic BP with a difference of -15 mm Hg (95% confidence interval (CI), -17 to -13 mm Hg, P < 0.001) for SphygmoCor and -2 mm Hg (95% CI, -4 to 0 mm Hg, P < 0.05) for Omron. In comparison with the invasive catheter measurement at the brachial artery, the oscillometric Omron device underestimated brachial systolic BP by -19 mm Hg (95% CI, -23 to -15 mm Hg, P < 0.001). CONCLUSIONS: Both devices underestimated central systolic BP, with a larger deviation by SphygmoCor. Nonetheless, these noninvasive estimations of central BP closely correlate with the invasive measurements, and can still be properly used, on the condition that device specific diagnostic thresholds become available.

Microalbuminuria in relation to the metabolic syndrome and its components in a Chinese population.

BACKGROUND: We investigated the prevalence of microalbuminuria and its association with the metabolic syndrome and its components in a Chinese population. METHODS: The study subjects were recruited from a newly established residential area in the suburb of Shanghai. We measured anthropometry, blood pressure (BP), fasting plasma glucose, and serum lipids, and collected spot urine samples for the determination of albumin-creatinine ratio. We defined microalbuminuria as a urinary albumin-to-creatinine ratio of 30 to 299 mg/g. The metabolic syndrome was defined according to the International Diabetes Federation criteria. RESULTS: The 1079 participants included 410 (38.0%) hypertensive patients, and 66 (6.1%) diabetic patients. The prevalence of microalbuminuria (4.3%) was 3.2 times higher in 167 patients with the metabolic syndrome than 912 subjects without the metabolic syndrome (12.0% vs. 2.9%, P < 0.0001). In multiple regression adjusted for sex, age, body mass index, current smoking, alcohol intake and the use of antihypertensive drugs, and mutually adjusted for the components, microalbuminuria was significantly associated with diastolic BP (odds ratio 1.74 for +10 mmHg; 95% confidence interval [CI] 1.10-2.76; P = 0.02) and fasting plasma glucose (1.18; 95% CI 1.01-1.41; P = 0.04), but not with waist circumference, systolic BP, or serum HDL cholesterol and triglycerides (P > 0.10). CONCLUSIONS: Microalbuminuria is common in the Chinese population, and much more prevalent in the presence of the metabolic syndrome, mainly attributable to elevated diastolic BP and plasma glucose.