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Biomedical subjects

J F Potter

Publications and source records attributed to J F Potter.

At least 55 records · Page 3Linked to original sources
PubMed1997

The reproducibility of cardiac baroreceptor activity assessed non-invasively by spectral sequence techniques.

Baroreceptor sensitivity (BRS) is increasingly used as a prognostic indicator in cardiovascular disease. Traditionally it has been measured using invasive techniques with pharmacological manipulation of blood pressure (BP). With the advent of newer methods to measure pulse interval and beat-to-beat changes in BP it is now possible, using sophisticated mathematical modelling techniques, to calculate cardiac BRS non-invasively. However, there are virtually no data on the reproducibility of these newer techniques and what factors may affect the repeatability of these measurements. We studied 39 subjects, aged 22-82 years, with a supine systolic BP range 97-160 mmHg and a diastolic BP range 57-94 mmHg on two occasions between 1 week and 6 months apart. Cardiac BRS was measured by power spectral analysis using Fast Fourier Transformation (FFT), sequence analysis (using up, down and combined sequences) and from phase IV of the Valsalva manoeuvre. There was no significant difference between visits for any of the methods for measuring cardiac BRS. Mean BRS values were similar for FFT (16.7 +/- 11.2 ms/mmHg) and sequence analysis (15.8 +/- 11.4 ms/mmHg); however, results using phase IV of the Valsalva manoeuvre were significantly lower (8.1 +/- 2.9 ms/mmHg, p < 0.0001). The coefficient of variation for the five measures of cardiac BRS varied from 16.8% for Valsalva-derived values to 26.1% for 'down' sequence analysis. However, in ten subjects BRS could not be calculated from the Valsalva manoeuvre. None of the independent variables tested (including age, BP levels and time between testing) significantly influenced the degree of repeatability. In summary, there appears to be little difference between these non-invasive methods in their degree of reproducibility. These techniques would seem suitable for longitudinal studies of changes in cardiac BRS and overcome many of the problems associated with the invasive pharmacological methods.

Adult↗
PubMed1997

Metabolic and orthostatic blood pressure responses to a low-sodium diet in elderly hypertensives.

In view of the concern regarding the potential risks and benefits of sodium restriction, the effect on biochemical and orthostatic responses from a moderate reduction in sodium intake in elderly persons that is sufficient to lower systolic blood pressure (SBP) was examined. Seventeen hypertensive subjects aged 65-79 years entered a double-blind randomized placebo controlled cross-over trial of a low sodium diet plus placebo tablets vs a low sodium diet plus sodium tablets (80 mmols/day) each for 5 weeks. At the end of high and low sodium periods, two 24-h urine collections and venous blood samples were undertaken and supine and standing BPs were recorded. On the low compared to the high sodium phase (urinary sodium excretion 95 +/- 36 vs 174 +/- 40 mmols/24-h, respectively), clinic supine SBP fell by 8 mm Hg (95% CI: 1-15 mm Hg, P< 0.05) and diastolic BP (DBP) by 1 mm Hg (CI: -3 to 5 mm Hg); there was no change in total LDL- and HDL-cholesterol and triglyceride levels, serum calcium, phosphate, parathyroid hormone, glucose, creatinine clearance or urinary albumin excretion rate. Serum urate was significantly higher during the low compared to high sodium intake (304 +/- 56 vs 277 +/- 44 micromols/l). Orthostatic BP responses during the high and low sodium intakes were unchanged. In summary, after 5 weeks of moderate sodium restriction no adverse effects other than an increase in serum urate was seen in elderly hypertensive persons.

Aged↗
PubMed1997

Endothelial function in subcutaneous resistance arteries from elderly hypertensive and normotensive subjects.

1. Previous studies have indicated that younger hypertensive subjects may have abnormal endothelium-dependent relaxation, which could contribute to the elevated peripheral resistance seen in established hypertension. This study was designed to examine the functional behaviour of the endothelium of small arteries from elderly hypertensive and normotensive subjects. 2. Resistance arteries were obtained from gluteal biopsies taken under local anaesthesia in 28 subjects of mean age 70 (range 60-76) years, and studied in an isometric myograph. Eighteen subjects had untreated essential hypertension, and 10 were normotensive. 3. After measurement of the contractile response to noradrenaline, relaxation responses to a variety of endothelium-dependent (acetylcholine and bradykinin) and endothelium-independent (iloprost and sodium nitroprusside) mechanisms were assessed in vessels precontracted with noradrenaline. Endothelium-dependent responses were also studied after incubation with NG-nitro-L-arginine to inhibit nitric oxide synthase. 4. There were no significant differences in the contraction or relaxation responses between elderly subjects with or without high blood pressure. Inhibition of nitric oxide synthase prevented any relaxation with acetylcholine and significantly attenuated the relaxation with bradykinin. Near-complete relaxation was however achieved with the endothelium-independent vasodilator sodium nitroprusside. 5. Hypertension in elderly subjects is not associated with a reduction in endothelial vasodilating function in the subcutaneous vessels of the gluteal region compared with age-matched normotensive controls. The results of this study do not support the hypothesis of a defect of resistance artery endothelium-dependent relaxation in the pathophysiology of hypertension in the elderly.

Acetylcholine↗
PubMed1997

Impulse response analysis of baroreceptor sensitivity.

The impulse response function (IRF) can express the dynamic relationship between systolic arterial pressure (SAP) and pulse interval (PI) and, consequently, represents an alternative method to assess baroreceptor sensitivity (BRS) in humans. Five normotensive and 13 hypertensive subjects (age 68 +/- 5 yr, range 60-74 yr) were studied at rest in the supine position during baseline conditions and after injections of phenylephrine and sodium nitroprusside. SAP and PI signals were derived from multiple 5-min noninvasive recordings of arterial blood pressure (Finapres) and electrocardiogram. Standard estimates of BRS were obtained by the slopes of transient changes in SAP and PI after the injection of phenylephrine and sodium nitroprusside (BRS(PE) and BRS(SNP)) and by spectral analysis (alpha-index). Impulse responses were obtained by the inverse Fourier transform of the transfer function between PI and SAP. The temporal pattern of the IRF was characterized by a main peak at t = 0, preceded by a "trough" at t = -1 s. A mathematical model of the baroreflex suggests that the peak value of IRF is linearly related to the BRS. The peak value and its smoothed version were shown to be significantly correlated to alpha, BRS(PE), and BRS(SNP) and significantly reduced in the hypertensive group during the three stages of the protocol. We suggest that IRF might be the ideal method to assess BRS because it does not require any subjective preselection of data segments or spectral bands.

Aged↗
PubMed1997

Long-term potassium supplementation lowers blood pressure in elderly hypertensive subjects.

Following a randomised cross-over trial of the effect of a four-week 60 mmol/day potassium supplement versus placebo on blood pressure (BP), eight of the original 18 hypertensive subjects continued with a 48 mmol daily potassium supplement for four months. For these eight subjects 24-h potassium excretion during placebo, one month of 60 mmol and four months of 48 mmol daily potassium supplementation phases was 56 +/- 23, 102 +/- 28 and 90 +/- 35 mmol/24 hours, respectively, and mean 24-h BP following each phase was 160 +/- 16/89 +/- 11, 147 +/- 13/83 +/- 12 and 145 +/- 14/81+/- 9 mmHg respectively, a significant fall in mean 24-h SBP between four months of potassium supplement and placebo period of 15 +/- 13 mmHg (95% CI: 4, 26 mmHg, p = 0.02), although the fall in 24-h DBP was not significant (8 +/- 11 mmHg, 95% CI: 0, 17 mmHg, p = 0.08). Modest increases in dietary potassium intake could have significant effects on lowering BP in the large proportion of elderly subjects with hypertension.

Aged↗
PubMed1996

Assessment of baroreceptor-cardiac reflex sensitivity using time domain analysis in patients with IDDM and the relation to left ventricular mass index.

Autonomic dysfunction in insulin-dependent diabetic (IDDM) patients has been associated with abnormalities of left ventricular function and an increased risk of sudden death. A group of 30 patients with IDDM and 30 age, sex and blood pressure matched control subjects underwent traditional tests of autonomic function. In addition, baroreceptor-cardiac reflex sensitivity (BRS) was assessed using time domain (sequence) analysis of systolic blood pressure and pulse interval data recorded non-invasively using the Finapres beat-to-beat blood pressure recording system. 'Up BRS' sequences-increases in systolic blood pressure associated with lengthening of R-R interval, and 'down BRS' sequences-decreases in systolic blood pressure associated with shortening of R-R interval were identified and BRS calculated from the regression of systolic blood pressure on R-R interval for all sequences. We also assessed heart rate variability using power spectral analysis and, after expressing components of the spectrum in normalised units, assessed sympathovagal balance from the ratio of low to high frequency powers. IDDM subjects underwent 2-D echocardiography to assess left ventricular mass index. Standard tests of autonomic function revealed no differences between IDDM patients and control subjects, but dramatic reductions in baroreceptor-cardiac reflex sensitivity were detected in IDDM patients. 'Up BRS' when supine was 11.2 +/- 1.5 ms/mmHg (mean +/- SEM) compared with 20.4 +/- 1.95 in control subjects (p < 0.003) and when standing was 4.1 +/- 1.9 vs 7.6 +/- 2.7 ms/mmHg (p < 0.001). Down BRS when supine was 11.5 +/- 1.2 vs 22 +/- 2.6 (p < 0.001) and standing was 4.4 +/- 1.9 vs 7.3 +/- 2.5 ms/mmHg (p < 0.003). There were significant relations between impairment of the baroreflex and duration of diabetes (p < 0.001) and poor glycaemic control (p < 0.001). From a fast Fourier transformation of supine heart rate data and using a band width of 0.05-0.15 Hz as low-frequency and 0.2-0.35 Hz as high frequency total spectral power of R-R interval variability was significantly reduced in the IDDM group for both low-frequency (473 +/- 62.8 vs 746.6 +/- 77.6 ms2 p = 0.002) and high frequency bands 125.2 +/- 12.9 vs 459.3 +/- 89.8 ms2 p < 0.0001. When the absolute powers were expressed in normalised units the ratio of low frequency to high frequency power (a measure of sympathovagal balance) was significantly increased in the IDDM group (2.9 +/- 0.53 vs 4.6 +/- 0.55, p < 0.002 supine: 3.8 +/- 0.49 vs 6.6 +/- 0.55, p < 0.001 standing). Thus, time domain analysis of baroreceptor-cardiac reflex sensitivity detects autonomic dysfunction more frequently in IDDM patients than conventional tests. Impaired BRS is associated with an increased left ventricular mass index and this abnormality may have a role in the increased incidence of sudden death seen in young IDDM patients.

Adult↗
PubMed1996

Abnormal baroreceptor-cardiac reflex sensitivity is not detected by conventional tests of autonomic function in patients with insulin-dependent diabetes mellitus.

1. Autonomic neuropathy is a common complication of diabetes mellitus and is a major risk factor for sudden death. 2. A group of 30 patients with insulin-dependent diabetes mellitus and 30 age-, sex- and blood pressure-matched control subjects underwent traditional tests of autonomic function. Resting supine R-R interval and systolic blood pressure variability were assessed using spectral analysis methods. In addition, we assessed the baroreceptor-cardiac reflex from the linear relation of the change in R-R interval to the increasing systolic blood pressure measured non-invasively with the Finapres monitor during phase 4 of the Valsalva manoeuvre and from resting heart rate and systolic blood pressure power spectra. 3. Whereas standard tests of autonomic function revealed no differences between patients with insulin-dependent diabetes mellitus and control subjects, there was a significant reduction in power spectral density of heart rate variability around the high-frequency region (125.2 +/- 112.9 versus 459.3 +/- 189.8 ms2, mean +/- SD). Furthermore, reductions in baroreflex sensitivity calculated from the Valsalva manoeuvre were detected in diabetics compared with controls (3.3 +/- 1.6 versus 9.5 +/- 2.5 ms/mmHg, mean +/- SD, P < 0.00001). There were significant relations between impairment of the baroreflex and duration of diabetes (P < 0.001) and poor diabetic control (P < 0.05). 4. In summary, autonomic dysfunction occurs much more frequently in diabetic patients than conventional tests would suggest. Abnormal baroreceptor-cardiac reflex sensitivity in patients with insulin-dependent diabetes mellitus may in part be explained by abnormal parasympathetic function. This unrecognized abnormality may have a role in the increased incidence of sudden death seen in young diabetic subjects.

Adult↗
PubMed1996

Arterial baroreceptor-cardiac reflex sensitivity in the elderly.

Uncertainty still remains regarding the differing effects of blood pressure and age on baroreceptor-cardiac reflex sensitivity in elderly individuals; these differences are at least partly due to the differing methods and subject groups used in previous studies. We sought to resolve these issues by examining baroreflex sensitivity in 54 subjects aged 70 +/- 1 years (mean +/- SE; range, 60 to 81) divided into groups with combined systolic-diastolic hypertension (CH group, n = 16), isolated systolic hypertension (ISH group, n = 16), or normotension (NT group, n = 22). Baroreflex sensitivity was quantified from the pulse interval and blood pressure responses to the Valsalva maneuver and pressor (phenylephrine) and depressor (sodium nitroprusside) stimuli. Baroreflex sensitivity was significantly reduced in the two hypertensive groups but did not differ between them (Valsalva maneuver: CH group, 1.9 +/- 0.3 ms/mm Hg; ISH group, 2.8 +/- 0.5; NT group, 4.4 +/- 0.4; phenylephrine: CH group, 3.1 +/- 0.6; ISH group, 3.5 +/- 0.7; NT group, 7.7 +/- 1.0; sodium nitroprusside CH group, 2.1 +/- 0.3; ISH group, 3.6 +/- 0.8; NT group, 5.4 +/- 0.3; all P < .05 for comparison with the NT group). Thus, this study demonstrated reductions in baroreflex sensitivity with hypertension in elderly subjects consistent across all methods but with no difference between subjects with combined hypertension and isolated systolic hypertension matched for similar systolic pressure. Baroreflex sensitivity was related only to the level of systolic pressure independent of diastolic pressure or age. If elderly subjects with isolated systolic hypertension have a greater reduction in large-artery compliance than combined hypertensive subjects with similar systolic pressure, this does not appear to lead to further reductions in baroreflex sensitivity in these individuals.

Aged↗
PubMed1996

Comparison of diurnal systolic blood pressure change as defined by wrist actigraphy, fixed time periods and cusum.

AIMS: To assess whether differences exist in nocturnal blood pressure (BP) levels and the diurnal BP change when using fixed time and wrist actigraphy methods to define the night-time period. METHODS: Untreated hypertensive (n = 48) and normotensive (n = 33) subjects (mean age 67 years: range 29-90) underwent simultaneous 24-h ambulatory BP monitoring and wrist actigraph monitoring. The diurnal BP change and nocturnal BP levels were assessed using two fixed night-time definitions-a reference period of 22.00-06.59 and also 00.00-05.59, as well as unedited and edited actigraph values and cumulative sums (cusums) analysis. RESULTS: The reference definition of night-time 22.00-06.59 resulted in the highest values for night-time BP compared to other definitions (p < 0.05), although actigraph defined night-time BP values were not significantly different from the more restrictive definition of night-time (00.00-05.59). Restrictive night-time, edited and unedited actigraph and cusums values for the day-night difference were all significantly greater than the value calculated using the reference night-time period. Dipping status changed significantly depending on which definition of night-time was used. CONCLUSIONS: Significant differences exist in nocturnal BP levels and circadian change between the various methods for defining night-time. The routine use of wrist actigraphy does not however appear to alter the value of night-time BP levels when compared to a more restrictive fixed-time definition of night-time.

Adult↗
PubMed1996

Differences in orthostatic blood pressure changes measured with an oscillometric blood pressure monitor and a mercury sphygmomanometer.

AIMS: To compare orthostatic blood pressure (BP) changes recorded with the SpaceLabs 90207 BP monitor (SL) and the standard mercury sphygmomanometer (HgS). METHODS: 85 hospital in-patients aged 60-90 years had nine BP measurements recorded by both instruments using the same arm sequential measurement technique in supine and standing position by two observers. Supine BP was taken as the final set of three supine measurements, ie, one made with the SL, and the mean of the two HgS readings immediately before and after the monitor reading. From the SL supine reading was subtracted the three standing SL monitor readings and from the mean of the 2 supine HgS readings was subtracted the six standing measurements taken by the HgS. The orthostatic BP changes recorded by the HgS immediately before and after each SL monitor reading were averaged and compared with the corresponding orthostatic change recorded by the monitor. RESULTS: The monitor underestimated orthostatic SBP changes at all 3 comparisons compared to the HgS; i) -0.9 +/- 14.9 vs 2.7 +/- 10.3 mmHg, p < 0.05; ii) 0.3 +/- 15.4 vs 4.5 +/- 12.1 mmHg, p < 0.05; iii) 3.5 +/- 16.9 vs 7.5 +/- 14.9 mmHg, p < 0.05, respectively. These differences were more pronounced in males than females. Orthostatic hypotension (defined as SBP fall on standing of > or = 20 mmHg) was recorded in males by the monitor in four (8%) and by the HgS in 12 (25%), p < 0.05. Mean orthostatic DBP changes were similarly recorded by the monitor and HgS. On average only 60% and 77% of orthostatic SBP measurements taken by both instruments agreed within 10 and 15 mmHg respectively while 75% and 88% respectively of orthostatic DBP changes agreed within these limits. CONCLUSION: Orthostatic BP falls measured by an automatic oscillometric BP monitor may not be equivalent to those taken with a HgS and their use adds a further variable to the comparison of orthostatic BP changes between studies.

Aged↗
PubMed1995

Screening tests for microalbuminuria in non-diabetic elderly subjects and their relation to blood pressure.

1. Microalbuminuria in non-diabetic elderly subjects is predictive of vascular disease and mortality, and related to levels of blood pressure. 2. This study was designed to examine whether more restricted periods of urine collection retained the relation to the prevailing level of blood pressure and successfully identified subjects with microalbuminuria. 3. Fifty elderly subjects (aged over 60 years) made two consecutive 24-h urine collections for measurement of urinary albumin excretion, divided between daytime and night-time periods. Thirty-three subjects also provided a random 'spot' urine sample. Clinic and 24-h ambulatory blood pressure were also recorded. 4. Median 24-h urinary albumin excretion was 15.75 mg; 17 subjects had microalbuminuria. The median 24-h albumin-creatinine ratio was 1.91 mg/mmol. A threshold albumin-creatinine ratio of > or = 3.0 mg/mmol in a random urine sample predicted microalbuminuria with 92% sensitivity and 90% specificity. Alternatively, threshold values of 2.5 mg/mmol for men and 4.5 mg/mmol for women in an overnight urine collection predicted microalbuminuria with 88% sensitivity and 100% specificity. 5. The closest relation between albumin-creatinine ratio and blood pressure was that between spot albumin-creatinine ratio and clinic systolic blood pressure (r = 0.64, P < 0.001). Albumin-creatinine ratio was generally related to clinic systolic blood pressure, diastolic blood pressure and ambulatory systolic blood pressure. Microalbuminuric subjects had significantly higher levels of clinic and ambulatory systolic blood pressure than non-microalbuminuric subjects. 6. Microalbuminuria in the elderly is most related to clinic systolic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Effect of hospitalization on conventional and 24-hour blood pressure.

Blood pressure (BP) levels, particularly in hypertensives, often fall on admission to hospital. Whether such a BP fall also occurs for BP measured automatically without the presence of medical and nursing staff and hence without the alerting reaction has not previously been studied. Twenty-two subjects, mean age 80 +/- 7 years (BP range 110-190/60-110 mmHg) underwent nurse-taken BP measurements and 24-hour non-invasive BP monitoring on admission to hospital and again after 5 days. Nurse-taken systolic BP (SBP) levels on admission fell significantly from 149 +/- 21 mmHg to 137 +/- 16 mmHg (p < 0.01) on day 2, to 131 +/- 16 mmHg on day 5 (p < 0.05). Mean diastolic BP (DBP) levels showed a less marked fall over 5 days from 87 +/- 12 mmHg to 84 +/- 11 mmHg (p < 0.05). Mean 24-hour BP levels showed no significant change from admission to day 5 (131 +/- 17/72 +/- 12 mmHg vs. 131 +/- 17/72 +/- 10 mmHg, respectively). In addition, nurse-taken SBP on day 5 was similar to mean 24-hour and daytime SBP taken on day 1 or day 5. Using shorter periods of BP monitoring gave similar mean BP levels to the full mean 24-hour BP level although BP reproducibility was poorer, even with more than 10 hours of BP monitoring. A period of automatic BP monitoring on admission to hospital will rapidly reveal a patient's sustained hospital BP level.

Aged↗
PubMed1995

Reproducibility of the circadian systolic blood pressure variation in the elderly.

OBJECTIVES: To establish the reproducibility of the nocturnal systolic blood pressure (SBP) change in elderly subjects and to examine the use of cumulative sums (cusums) analysis in the assessment of circadian SBP variation. SUBJECTS: Forty-two untreated elderly subjects (35 hypertensive, 7 normotensive) of mean age 75.5 years from the hypertension clinic at a large teaching hospital participated in a reproducibility study. METHODS: Twenty-four-hour ambulatory blood pressure monitoring was performed and repeated at a median interval of 2 months (range 2 weeks to 9 months). OUTCOME MEASURES: Reproducibility of circadian SBP variation from fixed time analysis of day-night SBP difference and from cusums-based parameters. RESULTS: Twenty-four-hour SBP values were highly reproducible with a coefficient of variation of 5.8%. However, the day-night SBP difference for fixed time periods was poorly reproducible, with a coefficient of variation > 130%. A substantial proportion of subjects (36-43%) altered their 'dipping status' between visits. The use of cusums analysis improved the reproducibility of measures of circadian SBP change (cusums plot height and maximum circadian variation) with coefficients of variation falling to 40 and 38%, respectively. CONCLUSIONS: The use of fixed time definitions results in poor reproducibility of the circadian SBP change in the elderly, which will lead to regression dilution bias when studying the relationship of circadian SBP variation to outcome measures in hypertension. The notion of dipping and non-dipping circadian blood pressure patterns should be abandoned in favour of more reproducible cusums-based measures of circadian blood pressure variation.

Aged↗
PubMed1995

The reliability and validity of the Geriatric Depression Rating Scale administered by telephone.

OBJECTIVE: To evaluate prospectively the reliability and validity of the Geriatric Depression Scale administered by telephone (T-GDS) in patients undergoing outpatient comprehensive geriatric assessment. SUBJECTS: A total of 101 geriatric patients were evaluated in a 1-year period at the outpatient Geriatric Assessment Center of the University of Nebraska Medical Center. METHODS: The 30-item GDS was completed by all patients on three occasions: by telephone several days before their assessment, face-to-face during their assessment visit, and several days later, again by phone. During their assessment, all patients were evaluated by one of three geriatric psychiatrists who were blind to all GDS results. The test-retest reliability of the T-GDS was measured by comparing the results of the two phone interviews. The construct validity of the T-GDS was estimated by comparing the results of the initial T-GDS to the GDS obtained during the comprehensive assessment. The criterion validity of the T-GDS was estimated by comparing the results of the T-GDS with the clinical diagnosis of depression assigned by the psychiatrists. RESULTS: The individual items of the initial T-GDS showed substantial concordance with the second T-GDS (kappa range 0.35-0.75, mean = 0.52), and with the assessment GDS (kappa range 0.29-0.75, mean = 0.52). One item showed evidence of bias when comparing the two T-GDSs, and two items when comparing the initial T-GDS to the GDS done during the assessment. The mean number of symptomatic responses was not significantly different for the T-GDS versus assessment administration but did decline slightly when comparing the two T-GDSs. ROC curve analyses showed good agreement between the clinical diagnosis and the T-GDS. CONCLUSION: The GDS appears to maintain its reliability and validity when administered via telephone and thus may be useful for a variety of epidemiological and clinical purposes.

Activities of Daily Living↗
PubMed1995

Pulse pressure and resistance artery structure in the elderly.

There has been recent interest in the possibility that resistance vessel structural adaptation in hypertension may be more closely related to pulse pressure than to other blood pressure parameters. We investigated the relation between blood pressure and resistance vessel structure in a group of subjects from an age group (older than 60 years) in which a widening of pulse pressure is a typical finding and characterized blood pressure parameters using 24-hour ambulatory blood pressure monitoring. We studied resistance vessels retrieved from biopsies of skin and subcutaneous fat taken from the gluteal region of 32 subjects under local anesthesia (age, 70 +/- 1 years [mean +/- SEM], 21 of whom were hypertensive and 11 normotensive. Media-lumen ratio was higher in the hypertensive than the normotensive subjects (18.6 +/- 1.6% versus 12.8 +/- 1.2%, P < .01) and correlated with age (r = .44, P < .05), clinic systolic pressure (r = .35, P < .05), 24-hour systolic pressure (r = .40, P < .05), and 24-hour pulse pressure (r = .56, P < .001). Stepwise multivariate regression analysis identified clinic and 24-hour pulse pressure as the only significant predictors of media-lumen ratio independent of age, other parameters of clinic blood pressure, and blood pressure variability (R2 = 41%, P < .05). These findings confirm those from animal models of hypertension in demonstrating the importance of pulse pressure in relation to cardiovascular structural adaptation and have important implications for the goals of treatment of hypertension in the elderly.

Aged↗
PubMed1995

Postprandial and orthostatic cardiovascular changes after acute stroke.

BACKGROUND AND PURPOSE: Large falls in blood pressure after meals have been demonstrated in fit and frail elderly subjects; these changes may be associated with an increased incidence of stroke. Postprandial falls in BP may be particularly deleterious after acute stroke, when normal baroreflex mechanisms and cerebral autoregulation are already impaired, resulting in stroke progression. Therefore, the postprandial hemodynamic responses to orthostasis were examined in nine acute stroke subjects and eight age-, sex-, and blood pressure-matched control subjects after an oral energy load. METHODS: All subjects were studied on two occasions in a randomized, double-blind, crossover trial after administration of either oral glucose (1 g/kg body wt) or equivalent isovolumic, isosmotic xylose (0.83 g/kg). Measurements of blood pressure, pulse rate, and forearm blood flow were recorded for 30 minutes preprandially and 90 minutes postprandially. Hemodynamic responses to 60 degrees tilt, along with plasma glucose and insulin changes, were measured at baseline and at 30-minute intervals postprandially. RESULTS: Supine mean arterial and diastolic blood pressures fell significantly after glucose but not xylose ingestion in control subjects (P < .03) but not stroke subjects, whereas supine pulse rate increased in stroke subjects (P < .04) only. No significant changes in forearm vascular resistance were recorded in either control or stroke subjects. After tilt, stroke subjects showed a fall in mean arterial pressure compared with control subjects preprandially (P = .03) and at 30 (P < .005) and 90 (P < .03) minutes postprandially, although no differences were observed between the xylose and glucose phases. Orthostatic tolerance was maintained in control subjects throughout both phases of the study. Pulse rate increased significantly to tilt at all time intervals in both groups, although there were no significant changes in forearm vascular resistance. CONCLUSIONS: Acute stroke subjects are not at significantly greater risk of blood pressure falls in response to an oral energy load than age-, sex-, and blood pressure-matched control subjects. Unlike control subjects, the stroke group had an increased pulse-rate postprandially, which could result in a compensatory rise in cardiac output as a result of increased sympathetic nervous system activity in the poststroke period. Although orthostatic blood pressure control is impaired after acute stroke, these changes are unaffected by meals.

Acute Disease↗