Masanori Munakata

Comparison between carotid-femoral and brachial-ankle pulse wave velocity as measures of arterial stiffness

Background Arterial stiffness is an important risk factor for cardiovascular disease. Carotid-femoral pulse wave velocity (cfPWV) is the most recognized and established index of arterial stiffness. An emerging automatic measure of PWV primarily used in the Asian countries is brachial-ankle PWV (baPWV). Method To systematically compare these two methodologies, we conducted a multicenter study involving a total of 2287 patients. Results There was a significant positive relation between baPWV and cfPWV (r = 0.73). Average baPWV was approximately 20% higher than cfPWV. Both cfPWV and baPWV were significantly and positively associated with age (r = 0.56 and 0.64), systolic blood pressure (r = 0.49 and 0.61), and the Framingham risk score (r = 0.48 and 0.63). The areas under the receiver operating curves (ROCs) of PWV to predict the presence of both stroke and coronary artery disease were comparable between cfPWV and baPWV. Conclusion Collectively, these results indicate that cfPWV and baPWV are indices of arterial stiffness that exhibit similar extent of associations with cardiovascular disease risk factors and clinical events.

Utility of automated brachial ankle pulse wave velocity measurements in hypertensive patients

BACKGROUND We examined whether pulse wave velocity (PWV), determined by brachial ankle arterial pressure wave measurements, using a newly developed, fully automated device could be a surrogate measure for carotid femoral PWV. METHODS & RESULTS This device (AT-form PWV/ABI, Nippon Colin, Komaki, Japan) can simultaneously monitor bilateral brachial and ankle pressure wave forms using the volume plethysmographic method, with two optional tonometry sensors for carotid and femoral arterial wave measurements. We examined the right brachial-right ankle PWV and left carotid-left femoral PWV in 89 normotensive and untreated hypertensive patients. The brachial ankle PWV correlated well with carotid femoral PWV (r = 0.755, P <.00001). The Bland-Altman plots of the two variables, however, showed a significant difference exists between the two techniques over the range of measurement. The within-observer and between-observer coefficients of variation of the brachial ankle PWV were 6.5% +/- 4.1% and 3.6% +/- 3.9%, respectively. To determine the factors affecting brachial ankle PWV, we studied treated and untreated hypertensive patients with World Health Organization stage I (n = 146), stage II (n = 74), or stage III (n = 54). In multiple regression analysis, age, brachial ankle PWV, and the presence of diabetes were significant predictors of the severity of hypertensive organ damage. Age, systolic blood pressure, and the stage of hypertensive organ damage were major determinants of brachial ankle PWV. CONCLUSIONS Although the brachial ankle PWV does not agree with the carotid femoral PWV, this parameter may yet become a new, useful measure for arterial stiffness. Further longitudinal studies are necessary to confirm the clinical significance of the brachial ankle PWV.

Altered circadian blood pressure rhythm in patients with Cushing's syndrome.

The circadian blood pressure rhythm was compared in patients with Cushings syndrome, essential hypertension, and primary aldosteronism. In patients with essential hypertension or primary aldosteronism, a clear nocturnal fall in systolic and diastolic blood pressure and heart rate was observed. This fall was seen in untreated subjects as well as in patients receiving combined treatment with a calcium antagonist, diuretic, converting enzyme inhibitor, alpha-blocker and beta-blocker, or sympatholytic drug. In these groups, there was a positive correlation between heart rate and systolic or diastolic blood pressure. On the other hand, in patients with Cushings syndrome, there was no nocturnal fall in blood pressure but in some patients a rise was observed. In all patients there was a nocturnal fall in heart rate. Thus, there was no significant correlation between heart rate and blood pressure in these patients. Exogenous glucocorticoid eliminated the normal nocturnal fall of blood pressure in patients with chronic glomerulonephritis or systemic lupus erythematosus. These results suggest that the changed circadian blood pressure pattern in patients with Cushings syndrome is not due to antihypertensive treatment or to the mineralocorticoid excess accompanying this disease, but it is attributable to excess glucocorticoid or the associated disturbance in the adrenocorticotropic hormone-glucocorticoid system (or both). This conclusion also implies that the normal circadian rhythm of blood pressure may be regulated at least in part by the adrenocorticotropic hormone-glucocorticoid system.

Ambulatory blood pressure of adults in Ohasama, Japan.

We performed a cross-sectional study in a small town in northern Japan to evaluate the distribution, reference values, and daily variation in ambulatory blood pressure. A total of 705 subjects (229 men aged 61.3 +/- 13.4 years [mean +/- SD] and 476 women aged 57.5 +/- 13.3 years; 41.1% of the regional adult population, n = 1716), including those treated with antihypertensive drugs (n = 231, 66.5 +/- 9.5 years) as well as untreated subjects (n = 474, 55.0 +/- 13.5 years), participated in the study. Both ambulatory and screening blood pressures were measured in 659 subjects. Ambulatory blood pressure was measured with an automatic device (Colin ABPM-630). The 24-hour ambulatory blood pressure in the total population was 121.7 +/- 13.0/71.1 +/- 7.6 mm Hg (95th percentile value [95%] = 146/85 mm Hg). The corresponding value in the untreated subjects was 119.4 +/- 12.5/70.1 +/- 7.4 mm Hg (95% = 144/83 mm Hg). The 24-hour average ambulatory blood pressure was 118.0 +/- 11.1/69.4 +/- 6.8 mm Hg (95% = 139/81 mm Hg) in subjects identified as normotensive by their screening blood pressure (n = 448, 57.2 +/- 13.1 years) and 133.6 +/- 14.2/78.9 +/- 8.8 mm Hg in those identified as hypertensive by their screening blood pressure (n = 73, 63.1 +/- 10.6 years). Based on the mean+SD of the 24-hour ambulatory blood pressure in the normotensive subjects by their screening blood pressure (129/76 mm Hg), the 24-hour ambulatory blood pressures in 25 (34.2%) of these 73 hypertensive subjects by screening blood pressure were below this level. Nine (2%) of 448 normotensive subjects by screening blood pressure were above the mean+2 SDs (140/83 mm Hg) of the 24-hour ambulatory blood pressure in the normotensive group by screening blood pressure. Ambulatory and screening blood pressures increased with age. The age-dependent increase in ambulatory blood pressure was less apparent in men. The 24-hour average pulse rate decreased with age. The daily variation in ambulatory blood pressure (standard deviation) increased with age, whereas that of pulse rate decreased with age. Increases in blood pressure variation were observed in nighttime and daytime blood pressure values. The differences between day versus night ambulatory blood pressures decreased with age in men but not in women.(ABSTRACT TRUNCATED AT 400 WORDS)

Characteristics of a community-based distribution of home blood pressure in Ohasama in northern Japan.

Objective: To evaluate the distribution, reference values and day-to-day variation of blood pressure of untreated subjects measured at home Design: Cross-sectional study of a cohort Setting: General community in northern Japan Subjects: Blood pressure was measured in 871 subjects (mean±SD age 46.0±19.5 years, range 7-98, constituting 38.7% of the local population of Uchikawama region, Ohasama) who were not receiving antihypertensive medication Methods: Subjects measured their own blood pressure at home at least three times (mean±SD 19.718.4) each morning using a semi-automatic oscillometric blood pressure measuring device. Screening blood pressure was measured once. Main outcome measures: Distribution of home blood pressure in the study population as a whole and with respect to age and sex, and the distribution of day-to-day variation of home blood pressure were determined Results: Mean home blood pressure was 117.3±13.4/69.3±9.7mmHg (95% confidence interval 116.4-118.2/68.7-70.0). The 95th centile value was 143/85 mmHg, mean + SD 131/79 mmHg and mean + 2SD 144/89 mmHg. Mean screening blood pressure was 126.2 ±18.9/72.1 ±11.7 mmHg (95th centile 159/92 mmHg). Age- and sex-specific 95th centile values as well as mean±SD were obtained. Mean + SD, mean + 2SD and the 95th centile values obtained as reference upper limits of home blood pressure from subjects identified as normotensive by screening blood pressure (n=707) were 125/77, 137/86 and 134/83 mmHg, respectively. Home blood pressure increased gradually with increasing age in both men and women, although blood pressure was significantly higher in men until 50 years of age. Day-to-day variation of home systolic blood pressure also increased with age Conclusions: Since the distribution of home blood pressure values was affected by age and sex, age- and sex-matched reference values for home blood pressure should be established. Home blood pressure values in elderly subjects should be evaluated carefully, since these exhibit greater day-to-day variation

Clinical evaluation of semiautomatic and automatic devices for home blood pressure measurement: comparison between cuff-oscillometric and microphone methods.

The accuracy and reliability of blood pressure (BP) values were evaluated by comparing values obtained with eight automatic or semiautomatic devices designed for home BP measurement (four microphone devices based on the Korotkoff-sound technique and four cuff-oscillometric devices) with those obtained by the auscultatory method, using a standard mercury sphygmomanometer. Systolic blood pressure (SBP) values obtained using the microphone devices coincided well with those obtained by the auscultatory method. However, these devices produced a certain proportion of errors in the measurement of diastolic blood pressure (DBP), sometimes resulting in recordings at least 25mmHg higher than those obtained by the standard method. The most frequent causes of this phenomenon were an auscultatory (silent) gap and a weak Korotkoff sound after phase IV. A microphone device using a condenser microphone built into the manometer displayed comparatively good acoustic characteristics for determining DBP. All cuff-oscillometric devices demonstrated minimal mean differences and a constant s.d. of mean difference for DBP, with no great differences from the auscultatory method. However, mean differences and s.d.s in SBP measurements using cuff-oscillometric devices were relatively greater than those obtained using some of the microphone devices. Furthermore, the direction of the mean differences in measurements from those obtained with the auscultatory method differed. The error in relation to the auscultatory method tended to be reproducible in the same subjects with both the microphone and the cuff-oscillometric devices. These results indicate that practitioners should select the most appropriate method and/or device by taking into account the factors which may cause measurement error in relation to the auscultatory method in each subject, and should then evaluate, at least once, the difference in BP values obtained using the auscultatory method and using the device. In future, home blood pressure measurement devices for determination of SBP should employ a microphone method, while a method which combines a microphone with a cuff-oscillometric device, thereby compensating for the disadvantage of the Korotkoff-sound signal with the pulse wave signal, should be recommended for measurement of DBP.

Exogenous glucocorticoid eliminates or reverses circadian blood pressure variations.

The effect of glucocorticoid on circadian variations of blood pressure was examined. In untreated patients with essential hypertension, a clear nocturnal fall in blood pressure and heart rate was observed and this was unaffected by combined treatment with antihypertensive drugs. The circadian blood pressure variation in patients with chronic glomerulonephritis (CGN) not receiving glucocorticoid treatment was essentially the same as that in patients with essential hypertension. In both groups there was a positive correlation between blood pressure and heart rate. On the other hand, in patients with CGN and systemic lupus erythematosus (SLE) who were treated with glucocorticoid, there was no nocturnal fall in blood pressure, and often a significant rise. In these patients the blood pressure was lowest in the afternoon and began to rise from then, and during the night, attaining a peak level in the morning. Despite this changed pattern of blood pressure variations, the heart rate in these patients was clearly reduced at night. In 10 patients with CGN and SLE, circadian rhythm of blood pressure and heart rate was examined before and during treatment with prednisolone (40.2 ± 17.0mg/day for 58.0 ± 19.4 days, mean ± s.d.). Prednisolone abolished the nocturnal fall of blood pressure, while the nocturnal fall of heart rate remained. There was no correlation between blood pressure and heart rate in patients with glucocorticoid treatment. These results suggest that the circadian blood pressure variation is influenced by the hypothalmo-pituitary-adrenal axis, probably through its action on the autonomic nervous system.

Higher Brachial-Ankle Pulse Wave Velocity Is Associated with More Advanced Carotid Atherosclerosis in End-Stage Renal Disease

Brachial-ankle pulse wave velocity is a new measure of arterial stiffness. We examined whether higher brachial-ankle pulse wave velocity is associated with more advanced carotid atherosclerosis and left ventricular hypertrophy in patients with end-stage renal disease, and whether this effect would be mediated by the influence of wave reflection on central arterial pressure. In 68 patients with end stage renal disease, we examined blood pressures, brachial-ankle pulse wave velocity and the augmentation index of the left common carotid artery, a measure of the impact of wave reflection on the systolic peak in central arteries. The degree of carotid atherosclerosis was quantified by a plaque score and maximum intimal-medial thickness. Echocardiography was used to determine the left ventricular mass index. In simple regression analysis, brachial-ankle pulse wave velocity was correlated with both plaque score and maximum intimal-medial thickness (r=0.420, p<0.001 and r=0.452, p<0.0005, respectively) but not with left ventricular mass index. Multiple regression analysis was performed with the plaque score or maximum intimal-medial thickness as the dependent variable and brachial-ankle pulse wave velocity and known clinical risk factors as the independent variables. The brachial-ankle pulse wave velocity was an independent risk factor for both plaque score (β=0.006, p=0.004) and maximum intimal-medial thickness (β=0.008, p=0.04). Independent risk factors for left ventricular mass index were left ventricular diastolic dimension (β=3.509, p=0.000007) and augmentation index (β=0.580, p=0.04). The brachial-ankle pulse wave velocity was unrelated to augmentation index in patients with end stage renal disease. In conclusion, higher brachial-ankle pulse wave velocity was found to be a risk factor for carotid atherosclerosis in patients with end-stage renal disease; this effect was independent of the influence of wave reflection on central arterial pressure. The brachial-ankle pulse wave velocity was unrelated to left ventricular structure.

Prognostic significance of the brachial–ankle pulse wave velocity in patients with essential hypertension: final results of the J-TOPP study

Brachial–ankle pulse wave velocity (baPWV) is a new tool for measuring arterial stiffness. The prognostic significance of this measure, however, is not fully established. We initiated a multicenter cohort study to examine the prognostic significance of baPWV in patients with essential hypertension in 2002. After baseline measurements were obtained, 662 previously untreated patients (mean age 60±12 years, mean blood pressure 156±19/94±12 mm Hg, 45% men) underwent long-term follow-up according to the current hypertension treatment guidelines. During the follow-up period (mean: 3 years, range: 3 months–8 years), 24 cardiovascular events were observed. The subjects were divided into high and low baPWV groups according to the median value (1750, cm s−1). Patients in the high baPWV group were older and had a lower body mass index, higher blood pressure, faster heart rate and higher fasting glucose and plasma creatinine concentrations compared with those in the low baPWV group. Cardiovascular morbidities per 1000 person-years for the high and low baPWV groups were 17.48 and 6.38, respectively (P<0.05), and the 8-year cardiovascular event-free survival rates were 78.2% and 93.5%, respectively (log-rank test, P=0.01). A multivariate Cox proportional hazard analysis showed that high baPWV compared with low baPWV was associated with a significantly poorer outcome (hazard ratio (HR) 2.97; 95% CI: 1.006–9.380). In conclusion, baPWV is an independent risk factor for future cardiovascular events in patients with essential hypertension.

Circadian blood pressure rhythm in patients with higher and lower spinal cord injury : simultaneous evaluation of autonomic nervous activity and physical activity

Objective To examine the relationships among the circadian rhythms of blood pressure, autonomic nervous function, and physical activity of patients with varying levels of spinal cord injury. Design and methods We studied 19 patients with spinal cord injury [10 tetraplegic patients with cervical cord injury (C4–C7), and nine paraplegic patients with thoracic cord injury (Th6–Th12)] compared with 16 control subjects. A new multibiomedical recorder was used to measure blood pressure (every 30 min), cardiac vagal activity (hourly frequency of R-R50), and physical activity (integrated acceleration/min) for 24 h under hospital conditions. Systemic sympathetic nervous activity and sympathoadrenal functioning were assessed by examination of hormone levels in the blood. Results Daytime and night-time values were compared; the variations in systolic and diastolic blood pressures and heart rate were slight in members of the tetraplegia group, but almost normal differences were observed in members of the paraplegia group. The circadian profile of cardiac vagal activity was normal for both patient groups, suggesting that an alteration in the sympathetic nervous rhythm had occurred in the tetraplegic patients. The plasma norepinephrine level was lower in members of the tetraplegia group than it was in members of the control group (P < 0.001), but was normal in members of the paraplegia group. The plasma level of epinephrine was lower in members of the tetraplegia (P < 0.05) and the paraplegia (P < 0.1) groups than it was in members of the control group. Daytime physical activity of members of both groups of patients was lower than that of subjects in the control group (P < 0.001 for both). Conclusion The central sympathoexcitatory pathway to the upper thoracic cord plays a critical role in the maintenance of normal circadian blood pressure rhythm in humans. Motor nerve functioning and sympathoadrenal secretion are not essential to this regulation.