Yoshiyuki Kawano

Circadian variation of haemodynamics in patients with essential hypertension: comparison between early morning and evening

Objective An increased incidence of cardiovascular accidents in the morning has been reported, but the reason why is not clear. We measured 24-h haemodynamics and focused on its change in the morning. Design To study the circadian variation of haemodynamics, we recorded 24-h direct blood pressure and electrocardiogram using a telemetry method, in 21 untreated inpatients with essential hypertension, and measured cardiac output using the dye-dilution method in the morning, in the evening and during sleep. We also determined the beat-to-beat cardiac output (using the pulse-contour method), the total peripheral resistance and the ratio of low- to high-frequency components (using power spectral analysis of the R-R interval during 24 h), and made comparisons between morning and evening values. Results Both systolic and diastolic blood pressure increased rapidly in the early morning. Although the comparison of blood pressure between morning and evening showed no difference, total peripheral resistance and low- to high-frequency ratio were significantly higher in the morning than in the evening, but cardiac output was lower in the morning. Conclusions Sympathetic nervous activity and vascular resistance seem to be higher in the morning than in the evening, and these haemodynamic changes may stress the cardiovascular system.

Angiotensin-Converting Enzyme Gene I/D Polymorphism and Carotid Plaques in Japanese

To clarify the role of genetic factors in atherosclerotic plaque formation in the carotid artery and magnetic resonance imaging abnormalities in the brain, we investigated the association of these abnormalities with the angiotensin-converting enzyme (ACE) genotype. One hundred sixty-nine subjects (age, 59.2+/-0.8 years, mean+/-SE) admitted to our hospital for health checkups underwent brain magnetic resonance imaging to evaluate lacunar infarction. B-mode ultrasound examinations of the carotid arteries were performed to detect atherosclerotic plaque. The I/D polymorphism of the ACE gene was determined by the polymerase chain reaction method. Multivariate regression analysis was performed to assess the effects of the following variables on the presence of plaque, mean plaque thickness, and number of plaques: fibrinogen, sex, age, body mass index, mean blood pressure, glycosylated hemoglobin, LDL cholesterol, HDL cholesterol, hematocrit, and the D allele of the ACE gene. The frequency of carotid atherosclerotic plaque was significantly (P=.034) higher in subjects with the D allele than in those without this allele. However, the frequency of lacunar stroke was similar in these groups. A multivariate regression analysis showed that the presence of plaque was independently associated with the D allele (odds ratio=3.27, P=.016). However, mean plaque thickness and the number of plaques were not associated with the D allele. The D allele of the ACE gene may be involved in the presence of carotid plaque but not in the extent of this plaque or asymptomatic lacunar stroke in Japanese subjects.

A new photo-oscillometric method employing the delta-algorithm for accurate blood pressure measurement.

Objective To measure blood pressure accurately, by developing a new algorithm and an indirect method employing a non-elastic cuff with a photosensor. Design and methods A non-elastic cuff was wrapped around the brachium. A reflecting plate (10 mm × 40 mm) was sited on the inner central part of the cuff on the arterial side. On the opposite side of the cuff, a photosensor consisting of light-emitting and light- receiving elements was positioned. Oscillation due to arterial pulsation was measured photologically during cuff inflation. Cessation of oscillation was taken as the systolic blood pressure (SBP) and, when the delay time between photo-oscillation and cuff-pressure oscillation upstrokes was at its minimum, the transition from rapid to more stable changes in photo-oscillation was taken as the diastolic blood pressure (DBP; the delta-algorithm). We compared the blood pressures measured directly in the brachial artery with those obtained by this method and by the conventional auscultatory method in 10 normotensive and 26 hypertensive subjects [12 women and 24 men, mean age 45 ± 16 years (mean ± SD), with mean brachial circumference 27 ± 2.6 cm]. The blood pressure of each subject was measured simultaneously by the direct and indirect methods five times. Results Errors (differences from direct blood pressure measurements) produced with this new method [SBP–0.8 ± 3.1 mmHg, (mean ± SD) DBP 0.6 ± 2.8 mmHg] were significantly smaller than errors obtained by use of the auscultatory method (SBP −7.4 ± 5.6 mmHg, DBP 3.0 ± 7.1 mmHg; P < 0.001, n = 180). The delta-algorithm was easily applicable to an automatic blood pressure measuring device. Conclusion This new photo-oscillometric method was more accurate than the auscultatory method for measuring blood pressure. The delta-algorithm is logical and will be useful for accurate blood pressure measurement.

Guanabenz combination therapy inhibits sympathetic nerve activity and regresses left ventricular hypertrophy.

The cardiovascular and sympatholytic effects of combination therapy with guanabenz were examined in 26 patients (48 ± 13 years old [mean ± SD]) with stage 2 and 3 hypertension. Included in the study were patients under treatment with conventional antihypertensive drugs whose systolic and diastolic blood pressure was above 140 and 90 mmHg, respectively. Blood pressure, heart rate, and sympathetic parameters such as plasma concentration of norepinephrine and muscle sympathetic nerve activity at rest as well as during ambulatory conditions, 24-hour urinary excretion of norepinephrine, and low frequency (LF: 0.04–0.15 Hz)/high frequency (HF: 0.15–0.4 Hz) power ratio as a marker of cardiac sympathetic activity during 24 hours were examined before and after guanabenz (4–8 mg/d) combination therapy with first-line antihypertensive drugs such as diuretics. Left ventricular mass index (LVMI) was also calculated by conventional echocardiography. After 32 weeks of guanabenz combination therapy, systolic and diastolic blood pressure, heart rate, plasma and urinary excretion of norepinephrine, muscle sympathetic nerve activity, and LF/HF power ratio were significantly decreased, while neither LF nor HF power was changed. LVMI was also significantly decreased (270 ± 81 vs. 236 ± 83 g/m2, p < 0.005). These results indicate that guanabenz combination therapy inhibits sympathetic nerve activity under resting conditions as well as during ambulatory conditions and may accelerate regression of left ventricular hypertrophy in patients with moderate to severe hypertension.