Supine Mean Arterial Pressure Research Articles

Development of prognostic nomogram model to predict syncope recurrence in children with vasovagal syncope.

Vasovagal syncope (VVS) is a common form of syncope. In children with VVS, recurrent syncope or presyncope can affect the physical and mental health of both children and parents, which markedly impairs quality of life. We aimed to identify factors at baseline that can predict the recurrence of syncope or presyncope over a 5-year follow-up period, and further to develop a prognostic nomogram model. This cohort is bidirectional in design. From July 2017 to August 2022, children with VVS were included and followed up every 3 to 6 months. Head-up Tilt Test (HUTT) was performed for diagnosing VVS. Data were analyzed using STATA software, and risk estimates are presented as hazard ratio (HR) and 95% confidence interval (CI). Total 352 children with VVS who had complete information were included in this study. Median follow-up time was 22 months. Overall, supine mean arterial pressure (MAP-supine) in HUTT and baseline urine specific gravity (USG) were associated with the significant risk of syncope or presyncope recurrence (HR: 0.70 and 3.00, respectively; both P < 0.05). Calibration and discrimination analyses revealed that the addition of MAP-supine and USG can result in a better fit. A prognostic nomogram model based on significant factors annexed with five traditional promising factors was finally constructed, with strong discriminative and predictive abilities (C-index approaching 0.700, P < 0.05). Our findings indicated that MAP-supine and USG can independently predict the significant risk of syncope recurrence in children with VVS, and the prediction was more obvious in a nomogram model.

Compliance with dietary guidelines affects capillary recruitment in healthy middle-aged men and women

PurposeHealthy microcirculation is important to maintain the health of tissues and organs, most notably the heart, kidney and retina. Single components of the diet such as salt, lipids and polyphenols may influence microcirculation, but the effects of dietary patterns that are consistent with current dietary guidelines are uncertain. It was hypothesized that compliance to UK dietary guidelines would have a favourable effect on skin capillary density/recruitment compared with a traditional British diet (control diet).MethodsA 12-week randomized controlled trial in men and women aged 40–70 years was used to test whether skin microcirculation, measured by skin video-capillaroscopy on the dorsum of the finger, influenced functional capillary density (number of capillaries perfused under basal conditions), structural capillary density (number of anatomical capillaries perfused during finger cuff inflation) and capillary recruitment (percentage difference between structural and functional capillary density).ResultsMicrovascular measures were available for 137 subjects out of the 165 participants randomized to treatment. There was evidence of compliance to the dietary intervention, and participants randomized to follow dietary guidelines showed significant falls in resting supine systolic, diastolic and mean arterial pressure of 3.5, 2.6 and 2.9 mmHg compared to the control diet. There was no evidence of differences in capillary density, but capillary recruitment was 3.5 % (95 % CI 0.2, 6.9) greater (P = 0.04) on dietary guidelines compared with control.ConclusionsAdherence to dietary guidelines may help maintain a healthy microcirculation in middle-aged men and women. This study is registered at www.isrctn.com as ISRCTN92382106.

Role of the ovarian cycle on neural cardiovascular control in sleep-deprived women

The midluteal (ML) phase of the ovarian cycle is often sympathoexcitatory compared with the early follicular (EF) phase. We recently reported that 24-h total sleep deprivation (TSD) augmented cardiovascular reactivity in both men and women, but that sex differences existed in resting muscle sympathetic nerve activity (MSNA) responses to TSD. In the present study, we hypothesized increased resting MSNA and augmented cardiovascular reactivity to acute laboratory stressors during the ML phase in sleep-deprived women. Heart rate (HR), mean arterial pressure (MAP), forearm vascular conductance (FVC), and MSNA were measured in 14 eumenorrheic women (age, 20 ± 1 yr) during 10 min supine rest, 5 min mental stress (MS) trial, and 2 min cold pressor test (CPT) trial. Subjects were tested twice after TSD: once during EF phase and once during ML phase (randomized, crossover design). Estradiol (29 ± 2 vs. 63 ± 8 pg/ml, P = 0.001) and progesterone (1.6 ± 0.2 vs. 4.4 ± 0.7 ng/ml, P = 0.002) were elevated during the ML phase. Resting supine MAP (75 ± 2 vs. 72 ± 1 mmHg, P = 0.042) was lower during the ML phase. In contrast, resting supine HR, MSNA, and FVC were not significantly different between EF and ML phases. MAP, HR and FVC reactivity to MS were not statistically different between the EF and ML phases. Similarly, MAP and HR reactivity to CPT were not different between the ovarian phases. Contrary to our original hypothesis, the ML phase was not associated with sympathoexcitation or exaggerated cardiovascular reactivity in sleep-deprived premenopausal women. However, our data reveal elevated resting blood pressure during the EF phase in sleep-deprived women.

Abstract 513: Impaired Hemodynamic Response to Head up Tilt in Adolescents Presenting with Chronic Nausea and Orthostatic Intolerance

We previously reported that ~70% of adolescents presenting to a Pediatric GI clinic for chronic nausea exhibit orthostatic intolerance (OI) in response to head upright tilt testing (HUT). The objective of this study was to determine whether supine mean arterial pressure or hemodynamic responses to HUT differ in these patients. Forty-eight patients (mean age of 15 [10-18] years, 36 females) completed a 45 minutes 0 to 70° HUT. Continuous blood pressure and heart rate recordings were acquired using non-invasive finger cuff. Thirteen subjects had normal tilt (Normal) while thirty five demonstrated OI. There were no differences between the two groups in supine blood pressures (BP), baroreflex sensitivity measured by frequency method in HF range (BRS), heart rate variability (HRV) measured as the root of mean square of successive differences (rMSSD), blood pressure variability (BPV) measured as standard deviation of mean arterial pressure (SDMAP) or the sympathovagal balance measure LF RRI /HF RRI . HUT caused a greater increase in heart rate in OI group (from 71 ± 6 beats/min to 104 ± 4 in OI vs from 75 ± 3 to 95 ±3 in normal, p=0.01) which was accompanied with lesser increase in BP (mainly due to lack of increase in diastolic) in the OI group. There was a trend for greater reduction in BRS in OI subjects (from 28.5 ± 13 ms/mm Hg to 6.3 ± 0.8 in OI vs from 21.1 ± 3.6 to 12.0 ± 2.9 in normal, p=0.09). HUT impaired HRV in both groups compared to supine values but the reduction was greater in OI group (-66.7 ± 4 % vs -52.0 ±5.6 in normal, p=&lt;0.001). SDMAP increased by HUT compared to supine but to a greater extent in OI (40.6 ± 4 % vs 13.4 ± 8 in normal, p=0.02). LF RRI /HF RRI increased to a greater magnitude in OI group with HUT (from 1.8 ± 0.8 to 6.8 ± 0.8 in OI vs from 1.14 ± 0.18 to 4.1 ±0.7 in normal, p=0.02). These data reveal that the adolescents with orthostatic intolerance have attenuated parasympathetic responses and exaggerated activation of the sympathetic system to the heart and blood vessels. Despite these responses, subjects fail to maintain BP. Similar to previous studies in other subjects with OI, the excessive tachycardia often followed by syncope in most of these adolescents may reflect a loss of vascular responses to the activation of sympathetic and neurohumoral stimuli. Support: AHA12CRP9420029

Physical exercise improves arterial stiffness after spinal cord injury

Objective/backgroundAortic pulse wave velocity (PWV), the gold-standard assessment of central arterial stiffness, has prognostic value for cardiovascular disease risk in able-bodied individuals. The aim of this study was to compare aortic PWV in athletes and non-athletes with spinal cord injury (SCI).DesignCross-sectional comparison.MethodsAortic PWV was assessed in 20 individuals with motor-complete, chronic SCI (C2–T5; 18 ± 8 years post-injury) using applanation tonometry at the carotid and femoral arterial sites. Ten elite hand-cyclists were matched for sex to 10 non-athletes; age and time since injury were comparable between the groups. Heart rate and discrete brachial blood pressure measurements were collected throughout testing.Outcome measuresAortic PWV, blood pressure, heart rate.ResultsAortic PWV was significantly lower in athletes vs. non-athletes (6.9 ± 1.0 vs. 8.7 ± 2.5 m/second, P = 0.044). There were no significant between-group differences in resting supine mean arterial blood pressure (91 ± 19 vs. 81 ± 10 mmHg) and heart rate (60 ± 10 vs. 58 ± 6 b.p.m.).ConclusionAthletes with SCI exhibited improved central arterial stiffness compared to non-athletes, which is in agreement with the previous able-bodied literature. This finding implies that chronic exercise training may improve arterial health and potentially lower cardiovascular disease risk in the SCI population.

Vitamin D deficiency is associated with orthostatic hypotension in oldest‐old women

Orthostatic hypotension, a condition that mostly affects 'oldest-old' (i.e. ≥80years) adults, is primarily explained by age-related dysfunction of blood pressure control. Vitamin D may contribute to blood pressure control. The aim of this study was to determine whether vitamin D deficiency is associated with orthostatic hypotension in oldest-old adults. Cross-sectional analysis at baseline of the EPIDOS study. Five French areas. A total of 329 community-dwelling oldest-old women (mean age 83.3±0.2years). Orthostatic hypotension was defined as a systolic blood pressure drop of ≥20mmHg and/or a diastolic blood pressure drop of ≥10mmHg within 3min of standing. Vitamin D deficiency was defined as a serum 25-hydroxyvitamin D (25OHD) concentration ≤10ngmL(-1) . Covariates included in the models were age, body mass index, diabetes mellitus, supine mean arterial pressure, number of drugs taken per day, use of antihypertensive or psychoactive drugs, cognition, quadriceps strength, current smoking, alcohol consumption, serum concentrations of parathyroid hormone, calcium and creatinine and season of testing. Diastolic orthostatic hypotension was observed more often among women with vitamin D deficiency (19.2%) compared to those without (10.0%; P=0.03). There was an inverse linear association between 25OHD concentration and change in diastolic blood pressure after 3min of standing (adjusted β=-0.07, P=0.046). Similarly, 25OHD deficiency was associated with orthostatic hypotension [adjusted odds ratio (OR) 3.36, P=0.004], specifically with diastolic orthostatic hypotension (adjusted OR 3.81, P=0.003). 25OHD deficiency was associated with orthostatic hypotension in oldest-old women, due to a greater drop in diastolic blood pressure on standing. This finding may lead to better understanding of the pathophysiology of falls in oldest-old adults with vitamin D deficiency.

Matrix Metalloproteinase-9 and Augmentation Index are Reduced with an 8-Week Green-Exercise Walking Programme

Objectives: MMP-9 is involved in degrading the Extracellular Matrix (ECM); specifically elastin, which provides elasticity to the arterial wall. Elastin degradation and restructuring of the ECM results in increased vascular remodelling and arterial stiffness. Conversely, exercise improves age-related vascular stiffening. Therefore, this study aimed to investigate whether participation in a green-exercise programme affects vascular haemodynamics and mRNA expression of MMP-9. Methods: Thirty-six healthy, sedentary individuals (44 ± 2yrs; not taking any cardiovascular-acting medication) joining a moderate-intensity, aerobic green-exercise programme, were recruited. At baseline and 8-weeks into the programme, physical activity (measured in weekly MET-minutes [IPAQ]), supine Mean Arterial Blood Pressure (MAP), Augmentation Index (AIx) and aortic Pulse Wave Velocity (aPWV) data were collected and blood samples were obtained. Leukocytic MMP-9 mRNA expression (RT-PCR) and plasma protein levels (ELISA) were analysed; AIx and aPWV were measured via applanation tonometry (SphygmoCor, Atcor Medical, Australia). Results: The cohort was split into those who adhered (n=17) and did not adhere (n=19) to the programme. MMP-9 expression, MAP and AIx all decreased significantly in the exercise-adherent group (cf. the non-adherent group), while significant correlations were seen between: (i) ΔMMP-9 expression and ΔMET-minutes/wk; (ii) ΔMMP-9 expression and ΔAIx; (iii) ΔAIx and ΔMET-minutes/wk (P<0.05 in all cases). aPWV did not change significantly between the groups. Conclusions: These findings suggest that exercise-induced down-regulation of MMP-9 may contribute to reduced ECM degradation and therefore ameliorate vascular remodelling. Additional studies are needed to explore these findings further; however, these data may provide a biomolecular mechanism for aerobic exercises ability to delay age-related increases in arterial stiffening.

Abstract 304: Elevated Supine Arterial Pressure in Children with Postural Orthostatic Tachycardia

Elevated supine mean arterial pressure (MAP) is often present in adults with dysautonomia. Children 15.1 ± 0.4 yrs of age (n = 22) with chronic unexplained nausea underwent continuous measures of supine blood pressure (BP) and heart rate (HR) pre- and post-tilt (0-70 degrees upright) and spectral analysis of their autonomic profile. Diagnostic workup revealed ∼77% have postural orthostatic tachycardia syndrome (POTS). The controls in this cohort had chronic nausea but were identified as normal upon tilt. Resting supine MAP and HR prior to tilt were higher in POTS subjects compared with controls, while most indices of autonomic function were similar (Table 1). Those diagnosed with POTS maintained MAP during tilt accompanied by a &gt;5-fold increase in cardiac sympathetic drive (LFrri/HFrri) and &gt;80% suppression of the baroreceptor reflex sensitivity (high frequency alpha index;HFα) in comparison to 2-fold and ∼60% responses in controls. BP variability (SDMAP) measured as the standard deviation of mean arterial presuure and HRV measured as the root of mean square of successive differences (rMSSD) were impaired to a greater extent in the POTS subjects. Exaggerated suppression of HRV during upright posture in POTS subjects is known. However, our studies reveal elevated supine MAP even at this young age. In adults, both impaired HRV and elevated supine MAP are risk factors for cardiovascular problems such hypertension and cardiac hypertrophy. Future studies are necessary to determine whether young adults with POTS are at greater risk of early onset cardiovascular disease, especially given the the potential impact of treatments aimed at increasing MAP. Support: AHA12CRP9420029

Vitamin D3 Therapy Corrects the Tissue Sensitivity to Angiotensin II Akin to the Action of a Converting Enzyme Inhibitor in Obese Hypertensives: An Interventional Study

Vitamin D deficiency and obesity are associated with increased tissue renin-angiotensin system (RAS) activity. The objective of the study was to evaluate whether vitamin D(3) therapy in obesity reduces tissue-RAS activity, as indicated by an increase in tissue sensitivity to angiotensin II (AngII). Participants included obese subjects with hypertension and 25-hydroxyvitamin D less than 25 ng/ml. Subjects were studied before and after 1 month of vitamin D(3) 15,000 IU/d, while in dietary sodium balance, and off all interfering medications. Fourteen subjects successfully completed all study procedures. The study was conducted at a clinical research center. At each study visit, tissue sensitivity to AngII was assessed by measuring renal plasma flow (RPF), mean arterial pressure (MAP), and adrenal secretion of aldosterone during an infusion of AngII. Subjects were then given captopril, and a second AngII infusion to evaluate the effect of captopril on tissue-RAS activity. Vitamin D(3) therapy increased 25-hydroxyvitamin D (18 to 52 ng/ml) and basal RPF (+5%) and lowered supine MAP (-3%) (all P < 0.01). There was a greater decline in RPF and higher stimulation of aldosterone with AngII infusion after vitamin D(3) therapy (both P < 0.05). As anticipated, captopril increased the renal-vascular, MAP, and adrenal sensitivity to AngII, but this effect was much smaller after vitamin D(3) therapy, indicating that vitamin D(3) therapy corrected the tissue sensitivity to AngII akin to captopril. Vitamin D(3) therapy in obese hypertensives modified RPF, MAP, and tissue sensitivity to AngII similar to converting enzyme inhibition. Whether chronic vitamin D(3) therapy abrogates the development of diseases associated with excess RAS activity warrants investigation.

The effects of ageing and passive heating on cardiorespiratory and cerebrovascular responses to orthostatic stress in humans

We tested the hypothesis that older adults, relative to younger adults, would be more prone to critical reductions in cerebral blood flow and oxygenation upon standing during passive heat stress. Six older (70+/-4 years, mean+/-s.d.) and six younger males (29+/-4 years) were heated (oesophageal temperature raised 0.5 degrees C) in a water-perfused suit. Blood flow velocity in the middle cerebral artery (MCAv), cerebral oxygenation, mean arterial pressure (MAP) and end-tidal partial pressure of carbon dioxide (PET,CO2) were measured continuously before and during 3 min standing in each thermal state. At supine normothermic baseline, MCAv was 47% lower in older participants (P<0.001), whilst MAP and cerebral oxygenation were similar between groups (P>0.05). Heating lowered the supine MAP more in younger adults, and elevated heart rate only in this group. Upon initial standing in normothermia, older participants had a greater drop in MCAv (P<0.05 versus young), a lesser drop in MAP (approximately 24 and approximately 42% in older and younger participants, respectively), but slower recovery of MAP (27.3+/-6.8 versus 18.6+/-4.7 s, mean+/-s.d., P=0.004); heating did not exacerbate any postural responses in either age group. During the last minute of standing, MCAv and PET,CO2 were lower in older participants, though age differences were not evident in cerebral oxygenation (normothermic or heated). Thus, independent of heat stress, in addition to lower resting MCAv, there are further age-related reductions in MCAv and slower corrections of MAP following standing. However, these asymptomatic changes seem to represent a physiologically acceptable insult which can be well tolerated in otherwise healthy older participants even during heat stress.

Contrasting effects of isocapnic and hypocapnic hyperventilation on orthostatic circulatory control

The effects of hyperventilation (HV) on mean arterial pressure (MAP) are variable. To identify factors affecting the MAP response to HV, we dissected the effects of hypocapnic HV (HHV) and isocapnic HV (IHV) and evaluated the effects of acute vs. prolonged HHV. In 11 healthy subjects the cardio- and cerebrovascular effects of HHV and IHV vs. normal ventilation were examined for 15 min in the supine position and also for 15 min during 60 degrees head-up tilt. The end-tidal CO(2) of the HHV condition was set at 15-20 mmHg. With HHV in the supine position, mean cerebral blood flow velocity (mCBFV) declined [95% confidence interval (CI) -43 to -34%], heart rate (HR) increased (95% CI 7 to 16 beats/min), but MAP did not change (95% CI -1 to 6 mmHg). However, an augmentation of the supine MAP was observed in the last 10 min of HHV compared with the first 5 min of HHV (95% CI 2 to 12 mmHg). During HHV in the tilted position mCBFV declined (95% CI -28 to -12%) and MAP increased (95% CI 3 to 11 mmHg) without changes in HR. With supine IHV, mCBFV decreased (95% CI -14 to -4%) and MAP increased (95% CI 1 to 13 mmHg) without changes in HR. During IHV in the tilted position MAP was further augmented (95% CI 11 to 20 mmHg) without changes in CBFV or HR. Preventing hypocapnia during HV resulted in a higher MAP, suggesting two contrasting effects of HV on MAP: hypocapnia causing vasodepression and hyperpnea without hypocapnia acting as a vasopressor.

Normalization of Supine Blood Pressure After Nitric Oxide Synthase Inhibition in Persons With Tetraplegia

Background/Objective: Orthostatic hypotension is a well-defined clinical consequence of spinal cord injury (SCI), particularly in those with tetraplegia. The etiology of orthostatic hypotension is thought to be loss of sympathetic vasomotor control, although other factors may play a role. There is evidence of up-regulation of nitric oxide synthase (NOS) activity after hind-limb suspension in rats, a condition of antigravity that may have similar vascular effects as shown in persons with tetraplegia caused by paralysis. The study objective was to determine the effect of a NOS inhibitor (nitro-L-arginine methyl ester [L-NAME]) on supine mean arterial pressure in persons with chronic tetraplegia compared with non-SCI controls.Methods: Fourteen individuals participated (7 with tetraplegia and 7 controls). Subjects visited the laboratory twice for placebo on day 1 and L-NAME (1 mg/kg) on day 2; both were infused intravenously over 60 minutes. Blood pressure was monitored for 3 hours after infusion at the brachial artery using a standard manual cuff.Results: Mean arterial pressure (MAP) was lower at baseline (P < 0.05) and after placebo administration (P < 0.0001) in the tetraplegia group compared with the control group. L-NAME increased MAP in both groups; however, the relative increase was greater in the tetraplegia group compared with the control group, such that group differences for MAP were eliminated. Supine MAP was normalized with L-NAME, and there was an increased sensitivity to NOS inhibition in the group with tetraplegia.Conclusions: These findings indicate that blood pressure dysregulation in persons with tetraplegia may reflect increased vascular NO and suggest a novel treatment of hypotension using NOS inhibition in this population.

Noninvasive hemodynamic assessment of the effect of mean arterial pressure on the amplitude of pulse pressure

The present study compares the relationships between mean arterial pressure (MAP) and pulse pressure (PP) in young and older men and whether MAP determines age-related changes in PP. Impedance cardiography was used to evaluate systemic hemodynamics noninvasively in 189 unmedicated men referred to our hypertension unit. Patients were divided by age according to the median value (< and >/=40 years). In younger patients, increasing supine MAP was associated with a transition in the blood pressure pattern from systolic to diastolic, whereas in older patients, increasing MAP was associated with change from diastolic to systolic hypertension. In young patients elevation in MAP was associated with a parallel decrease in PP (P < .001) and stroke volume index (SVI) (P < .001), whereas in older patients higher MAP was associated with higher PP (P < .001) and PP/SVI ratio (P < .001), a measure of arterial stiffness. When the sample was divided according to the median value of MAP (< and >/=101 mm Hg), differences in the age-related change in PP and SVI became apparent. With a lower MAP, changes in PP and SVI remained parallel until the sixth decade, after which they began a progressive dissociation. In contrast, at higher MAP, the dissociation between PP and SVI began two decades earlier, indicating an acceleration of the age-related increase in arterial stiffness. Therefore, the relationship between MAP and PP was negative in younger men at the expense of a decrease in SVI, and positive in older men due to increasing arterial stiffness. Noninvasive hemodynamic parameters from impedance cardiography provide a useful method to characterize the mechanism of increased blood pressure.

Hemodynamic changes after levothyroxine treatment in subclinical hypothyroidism.

In hypothyroidism, lack of thyroid hormones results in reduced cardiac function (cardiac output [CO]), and an increase of systemic vascular resistance (SVR). We speculated whether hemodynamic regulation in subjects with subclinical hypothyroidism (SH) (defined as mildly elevated thyrotropin [TSH] despite free thyroxine [T(4)] and triiodothyronine [T(3)] estimates within reference range) would benefit from levothyroxine (LT(4)) substitution. CO was measured by impedance cardiography, which is an observer independent method with high precision, and mean arterial pressure (MAP) by oscillometry. SVR was then calculated as MAP/CO. Measurements were performed before and after 60 degrees head-up tilting, and before and after LT(4) substitution. Plasma levels of catecholamines were also measured. In 16 otherwise healthy women with SH (ages 44-74 years; serum TSH in mean 17.1 mU/L (range, 6.8-27), and normal free T(4) and T(3) estimates) LT(4) treatment resulted in 6% reduction in supine MAP (p < 0.01), 14% increase in upright CO (p < 0.05), and 13%-20% decrease in SVR (supine and upright position, respectively) (p < 0.05). Plasma norepinephrine as well as epinephrine decreased during LT(4) treatment (p < 0.05). These changes were qualitatively similar but quantitatively less pronounced than in 15 women with overt hypothyroidism, also studied. Taking the two groups together (n = 31), pretreatment thyroid function (expressed as either TSH or free T(4) estimate) correlated to CO and SVR as well as the changes induced by LT(4) (p < 0.05), i.e., the lower the thyroid function the lower the CO and the higher the SVR, and the greater the response to LT(4). We conclude, that LT(4) treatment in SH results in changes in hemodynamic parameters of potentially beneficial character. SH and overt hypothyroidism should be regarded as a continuum, and our data favor earlier and more aggressive treatment of SH.

The sit-up position in breast surgery.

Breast shape is best evaluated while the patient is in an upright position. However, many surgeons are reluctant to have a patient sit upright during surgery because of concerns over the patient's hemodynamic instability. Therefore, the purpose of this study was to prospectively measure cardiovascular parameters, including heart rate and mean arterial pressure, in a series of 30 patients who were placed upright during various aesthetic and reconstructive breast procedures. Data regarding the number of times the patient was placed upright and the amount of time spent in the upright position were also recorded. Measurements were obtained immediately before and after elevating the head of the bed to 80 to 90 degrees during the procedure. The average supine mean arterial pressure was 73 +/- 3 mmHg and that for an upright position was 70 +/- 3 mmHg. The average supine heart rate was 73 +/- 4 beats per minute and that for an upright position was 76 +/- 4 beats per minute. Although the difference between these results is statistically significant (p < 0.05), there was no clinical significance to placing patients in an upright seated position in this study, and no patient had to be laid back down because of hemodynamic instability. Therefore, the upright seated position is strongly advocated for intraoperative evaluation of breast shape, and a safe and effective method to accomplish this is described.

Effects of age and gender on the pharmacodynamics of omapatrilat in healthy volunteers.

Omapatrilat is the most clinically advanced member of a new class of cardiovascular drugs, vasopeptidase inhibitors. Omapatrilat is a single molecule that simultaneously inhibits neutral endopeptidase and angiotensin-converting enzyme, thus preserving vasodilator peptides and inhibiting production of the vasoconstrictor angiotensin II. In healthy male volunteers, omapatrilat decreased blood pressure while being generally well tolerated, with no serious adverse events. This study was undertaken to determine the effect of age and gender on the pharmacodynamics of omapatrilat. Healthy male or female volunteers between the ages of 18 and 80 were given a single oral dose of omapatrilat 40 mg. Neither age nor gender affected the vasopeptidase inhibition by omapatrilat. There were no differences between subject groups in the effect of omapatrilat on supine systolic, diastolic, or mean arterial blood pressure. Based on this study of healthy subjects, it can be concluded that it is not necessary to adjust the initial dose of omapatrilat for the treatment of hypertension based solely on age or gender.

Autonomic and neurohumoral control of postprandial blood pressure in healthy aging.

Postprandial hypotension (PPH) is a common and morbid problem in elderly people that is associated with an impaired vascular response to meal digestion. Healthy aging in the absence of blood pressure elevation is associated with autonomic and neurohumoral changes that may influence the vascular response to meal ingestion. However, it is not known whether these age-related changes are associated with the development of PPH. We measured hemodynamic (blood pressure, heart rate, and forearm vascular resistance), autonomic (power spectral analysis of heart rate and blood pressure variability), and neurohumoral (plasma norepinephrine, renin, aldosterone, and endothelin) responses to a mixed 425 kilocalorie (kcal) meal in 89 rigorously screened healthy subjects aged 20-39, 40-59, and 60-83 years. After the meal, supine mean arterial blood pressure fell significantly only in the middle-aged group by 5.4 +/- 7.9 mm Hg at 30 minutes (p = .02). Forearm vascular resistance fell after the meal in all age groups ( p = .0001). Older groups had higher plasma norepinephrine (p = .02), lower heart rate (p = .03), lower cardiovagal activity (p = .0001), and lower sympathetic vasomotor (p = .000) activity, but there was no difference in the response of these variables to a meal. Healthy aging, in the absence of blood pressure elevation, alters the level of autonomic activity without further impairing the ability to maintain blood pressure during meal digestion. Hemodynamic, autonomic, and neurohumoral responses to meal ingestion remain unchanged in very healthy, normotensive elderly adults.

Relationship of co-morbidities of obesity to weight loss and four-year weight maintenance/rebound.

This study examined the effect of weight loss (separate from energy restriction) and weight maintenance/rebound over time on blood pressure, serum lipids, and body composition in 24 obese (mean 137% ideal body weight (IBW)) females with mild to moderate hypertension. Weight loss was induced under tightly controlled General Clinical Research Center conditions until each subject had lost at least 10 kg (mean 13 kg) and attained normal body weight (< 120% IBW). After 4 years subjects returned for repeat evaluation. Weight changes were compared with 24 pair-matched normal weight controls who were also followed for 4 years. With weight loss, significant improvements were seen in standing mean arterial pressure (MAP), serum total cholesterol, low-density lipoprotein cholesterol, and triglycerides. Subjects regained 11 kg (87% of the weight lost) over the 4 year follow-up period while control subjects gained only 2 kg. Subjects who chose self-selected exercise gained less weight than nonexercisers (6 kg vs. 13 kg, P < 0.05). With weight regain there were significant increases in standing and supine MAP, total cholesterol, and high-density lipoprotein (HDL) cholesterol. The amount of weight regained was significantly correlated with standing MAP (r = 0.73), triglycerides (r = 0.43), and HDL cholesterol (r = -0.47). The percentage fat of the weight regained was no greater than that of the weight previously lost. Weight loss, distinct from energy restriction, was associated with improvements in blood pressure and serum lipid levels. The ability to sustain these improvements in the co-morbidities of obesity was directly related to the persistence and magnitude of weight loss maintenance.

Postprandial Hypotension in Elderly Patients With Unexplained Syncope

Syncope in older patients may be caused by a variety of disorders, including hypotension, but frequently remains unexplained. Postprandial hypotension is a common disorder of blood pressure regulation in the elderly. To determine the pathogenic mechanisms and potential role of postprandial hypotension in elderly patients with otherwise unexplained syncope. We studied 16 elderly patients with unexplained syncope and nine elderly controls. Blood pressure, heart rate, forearm vascular resistance, plasma norepinephrine level, and cardiac and splanchnic blood volumes were measured before and after a 1680-kJ meal. Eight elderly patients with syncope had postprandial hypotension, with a decline in supine mean arterial blood pressure of 17 +/- 2 mm Hg after a meal (P < .001). The blood pressure remained unchanged after the meal in the other patients with syncope and the controls. In patients with postprandial hypotension, systemic vascular resistance fell after the meal, while it remained unchanged in the other groups. Heart rate and plasma norepinephrine level increased to a similar extent in all three groups. Forearm vascular resistance increased only in the control subjects. Splanchnic blood volume increased by 26% (P < .01) in patients with syncope who had postprandial hypotension and by 22% (P < .01) in control subjects. Splanchnic blood volume remained unchanged in the patients with syncope without postprandial hypotension. Postprandial hypotension may be an important causative factor in elderly patients with unexplained syncope. The evaluation of syncope in elderly patients should therefore include blood pressure measurements surrounding a meal. Elderly patients with syncope who have postprandial hypotension fail to maintain systemic vascular resistance, probably because of splanchnic blood pooling without a compensatory increase in peripheral vascular resistance.

Oscillometric Measurement of Mean Arterial Pressure: The Effect of Position on Prediction of Pregnancy Induced Hypertension

SummaryTo explain reported differences in the predictive ability of mean arterial pressure for proteinuric and non-proteinuric pregnancy induced hypertension, a prospective comparison was conducted of second trimester mean arterial pressure measured in left lateral and supine positions using a Dinamap.Thirty-four patients developed pregnancy induced hypertension, 15 with proteinuria. Left lateral mean arterial pressure predicted proteinuric pregnancy induced hypertension better than supine mean arterial pressure (P = 0.05), whereas non-proteinuric pregnancy induced hypertension was predicted rather better by supine mean arterial pressure (P<0.1).Differences in reports of mean arterial pressure prediction of pregnancy induced hypertension relate to differences in patient positioning and instrumentation.