Akiko Kawamoto

Accuracy of a continuous blood pressure monitor based on arterial tonometry.

A validation study of the continuous noninvasive tonometric blood pressure monitor called JENTOW was performed in 20 normotensive subjects and 10 hypertensive patients. Tonometric and intra-arterial blood pressures were simultaneously recorded at supine rest and during a Valsalva maneuver and tilting test. The results of the strict evaluation of the instruments capacity for reproducing intra-arterial blood pressure were as follows: 1) The overall frequency response of the transcutaneous blood pressure-monitoring system based on arterial tonometry was flat, with negligible delay to intra-arterial blood pressure in the range of 0-5 Hz. 2) The largest discrepancy between intra-arterial and tonometric pressure waveforms was found at the early systolic phase; except for this phase, the tonometric waveform was almost equal to the intra-arterial waveform. 3) The beat-to-beat variability of tonometric pressure corresponded to that of intra-arterial pressure almost perfectly in the physiologically significant frequency range of 0-0.5 Hz. 4) During resting conditions, the averages of the systolic and diastolic values measured tonometrically corresponded well to those measured intra-arterially. 5) The changes in the between-method discrepancy of blood pressure values during the Valsalva maneuver were statistically significant but small (< 5 mm Hg). 6) No significant effect of postural tilting was found on the between-method discrepancy. We conclude that this method is clinically acceptable and reliable except for its limited capacity for recording the higher frequency intra-arterial waveform and for responding to the relatively rapid and large transient changes in blood pressure.

Incidental brain lesions on magnetic resonance imaging and neurobehavioral functions in the apparently healthy elderly.

Controversies exist whether incidental neuroradiological brain lesions in the elderly are associated with depressed neuropsychological function. To address this important issue in a cross-sectional study, we related brain lesions on magnetic resonance imaging to a variety of cognitive and neurobehavioral function tests in an independent, normal elderly population. Methods We studied 73 independent asymptomatic elderly individuals (mean±SD age 70±6 years) to determine the relations between degree of brain atrophy, location and number of “lacunes,” and grade of periventricular hyperintense lesions with a variety of cognitive and neurobehavioral function scores. Results We found that severity of neuroradiological changes increased while neuropsy-chological function scores declined with age. After adjustment for the effect of age, advanced periventricular hyperintensities, but not brain atrophy or patchy “lacunar” lesions, were associated with declines in all neuropsychological functions tested. Conclusion We conclude that incidental advanced periventricular diffuse or patchy white matter changes may play a role in the development of cognitive and neurobehavioral impairments in apparently normal elderly persons.

FACTORS ASSOCIATED WITH SILENT MULTIPLE LACUNAR LESIONS ON MAGNETIC RESONANCE IMAGING IN ASYMPTOMATIC ELDERLY HYPERTENSIVE PATIENTS

1. Factors associated with advanced cerebrovascular damage incidentally seen on brain magnetic resonance imaging (MRI) were investigated in a population of 34 normotensive and 54 hypertensive asymptomatic elderly individuals (69±5 years).

Cardiovascular regulatory functions in elderly patients with hypertension.

To dissociate the effects of an elevated blood pressure on the cardiovascular regulatory functions from those of aging in the hypertensive elderly individual, resting hemodynamic measurements and circulatory autonomic functions in 30 elderly (mean age, 66 years) hypertensive (World Health Organization stages I and II) patients were compared with those in 30 healthy elderly (mean age, 65 years) normotensive volunteers. The elderly hypertensive group showed a significantly lower cardiac index and higher total peripheral resistance. beta-Receptor sensitivity, as determined by chronotropic dose of infused isoproterenol, and baroreceptor reflex sensitivity index, derived from phase II, but not phase IV, of Valsalvas maneuver, were only slightly but significantly reduced in the hypertensive group. The variability of heart rate at rest as an index of parasympathetic control of heart was similar between these two groups. Plasma norepinephrine level was significantly inversely related to resting mean blood pressure (r = -0.31, p less than 0.05) when analyzed as a whole group. Plasma renin activity, but not plasma aldosterone, was significantly decreased in the hypertensive group. To define the effects of age itself, these parameters in normotensive elderly subjects were also compared with those in 12 young normotensive subjects (mean age, 23 years). Although resting hemodynamic measurements did not differ, various circulatory autonomic functions were significantly different between these two age groups. The variability of heart rate in 24-hour ambulatory monitoring, beta-receptor responsiveness, resting vagal cardiac activity, and baroreceptor reflex sensitivity derived from phase IV of Valsalvas maneuver were significantly depressed in the elderly. Resting plasma norepinephrine level was elevated and renin-aldosterone system decreased in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure and Diastolic Function in the Elderly

To evaluate the relation between blood pressure and diastolic function in the elderly, 28 apparently healthy volunteers underwent blood pressure measurements, echocardiographic examinations, and radionuclide angiography acquired in list mode. Casual blood pressure did not correlate with diastolic indices measured either by echocardiography or by a radionuclide method, except for peak filling rate during atrial contraction assessed by radionuclide angiography (r = 0.39, p < 0.05). Ambulatory blood pressure monitoring revealed significant correlations between peak filling rate during atrial contraction assessed by radionuclide angiography and blood pressure measured over 24 hours, while awake and during sleep. The time to peak filling rate and the velocity of early diastolic filling were found to correlate with blood pressure, but the best correlation was between blood pressure during sleep and peak filling rate during atrial contraction (r = 0.53, p < 0.005). These results show a direct relation between blood pressure and diastolic function in the elderly, which is stronger during sleep than during wakefulness.

Comparison of Cardiovascular Regulatory Functions in Elderly Hypertensive Patients and Normal Elderly Subjects

In order to dissociate the effects of an elevated blood pressure on cardiovascular regulatory functions from those of aging in elderly hypertension, resting hemodynamic and circulatory autonomic functions of 30 elderly hypertensive patients were compared with those of 30 healthy, age-matched, normotensive volunteers with mean age of 65 years. The hypertensives showed significantly lower cardiac index and higher total peripheral resistance. s-receptor and baroreflex sensitivity indices were only marginally reduced in hypertensives as compared to normotensives, while the variability of the resting heart rate as an index of cardiac parasympathetic control did not differ between the two groups. Plasma renin activity, but not plasma aldosterone, was significantly decreased in the hypertensives. Group results showed plasma norepinephrine level inversely related to resting mean blood pressure (r = -0.31, P < 0.05). Thus, it is unlikely that either sympathetic nervous system or reninangiotensin system is responsible for the increase in peripheral resistance in elderly hypertension. Furthermore, high blood pressure has a very limited influence on circulatory regulatory functions, which in the older subjects have already been substantially altered by age.