Reproducibility of circulatory changes to head-up tilt in healthy elderly subjects

OBJECTIVE: to assess the reproducibility of the cardiovascular responses to head-up tilt including cardiac output, stroke volume and peripheral resistance, in healthy older subjects using non-invasive methods. PARTICIPANTS: twenty-five healthy community-dwelling volunteers with a mean age of 69+/-3 years. METHODS: the subjects underwent head-up tilt table testing on two occasions at an interval of 6 weeks. Pulse interval and blood pressure data were collected, on a beat-to-beat basis using a non-invasive monitor (Finapres, Ohmeda), during 70 degrees head-up tilt table testing and stored for analysis. ANALYSIS: the pulse interval and blood pressure data for the group were pooled and the relative changes in cardiac output, stroke volume and peripheral resistance were calculated using pulse contour analysis. RESULTS:the systolic blood pressure, pulse interval, cardiac output and stroke volume fell immediately after tilt with a rise in peripheral resistance. These responses were similar, though the baseline systolic blood pressure levels were lower at the second visit (P=0.06). CONCLUSION: these non-invasively assessed cardiovascular responses to head-up tilt in healthy older subjects show little variation between visits. The reproducibility of the responses in subjects with syncope and autonomic failure warrants further investigation.     

Hemodynamic study of 85 patients with borderline hypertension

Hemodynamic changes in supine and upright position (50 ° head-up tilt) and during exercise were studied in 40 normal subjects and 85 patients with borderline hypertension. The latter were classified in 2 groups, according to the level of cardiac index. In group I, with patients in the supine position, cardiac index, stroke index, heart rate and plasma volume were normal, but total peripheral resistance was increased (P < 0.01). During upright tilt, orthostatic decrease of mean arterial pressure (P < 0.05) was observed, and the increase in total peripheral resistance was not greater than in normal subjects. The hemodynamic response to exercise was similar to that of normal subjects. In patients in group II, cardiac index, stroke index and heart rate were increased (P < 0.001), but plasma volume was decreased (P < 0.01) and total peripheral resistance was below normal (P < 0.001). With patients in the upright position, diastolic orthostatic hypertension was observed (P < 0.001) and total peripheral resistance was greater than normal (P < 0.01) despite an abnormal fall of cardiac index (P < 0.05). The hemodynamic response to exercise indicated that total peripheral resistance did not decrease as in normal subjects and in patients of group I (P < 0.001). This study provides evidence that (1) total peripheral resistance is abnormal in patients with borderline hypertension, but only during upright tilt and exercise in patients with high cardiac index, and (2) 2 main disorders seem to be important in the early stage of hypertension: abnormality of blood volume (or blood volume distribution, or both) and impaired neurogenic activity.     

Influence of left ventricular diastolic function on vascular and humoral responses to head-up posture in hypertension

The left ventricular (LV) diastolic filling rate has been reported to be reduced in hypertensive patients. To investigate the possible influence of altered LV diastolic function in hypertension on peripheral vascular regulation, hemodynamic measurements were obtained in 16 hypertensive patients in the resting supine position and during head-up tilt. The study population included seven men and nine women with an age range of 30 to 62 years (mean, 49.5 years +/- 10.6). Measurements included LV peak filling rate (+dv/dt), LV peak ejection rate (-dv/dt), LV ejection fraction, heart rate, total peripheral resistance, stroke volume, and cardiac index. Moreover, we calculated the ratio relating left ventricular filling rate to left ventricular ejection rate (+dv/dt/-dv/dt) because a complex interaction between ventricular contraction and relaxation is well recognized. We observed that in patients with slow diastolic filling rate (ratio +dv/dt/-dv/dt less than 0.9), the increase in total peripheral resistance in response to head-up tilt was less marked than in those with normal LV filling rate (+dv/dt/-dv/dt greater than or equal to 0.9), whereas changes in stroke volume during tilt were not statistically different between the two groups. Conversely, supine resting cardiac index and total peripheral resistance was not significantly different among groups. We conclude that abnormal diastolic filling is associated with abnormal cardiovascular adjustment to changes in body posture. We suggest that the altered response to head-up posture is related to decreased sensitivity of low pressure receptors in the cardiopulmonary area as a result of impaired LV diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiovascular autonomic dysfunction in familial Mediterranean fever

OBJECTIVE: To compare the hemodynamic responses to autonomic challenge evoked by upright tilt table testing in patients with familial Mediterranean fever (FMF). METHODS: Forty consecutive patients with FMF and 25 age and sex matched healthy controls were evaluated using the head-up tilt test (HUTT). The main outcome measures were the values of blood pressure (BP) and heart rate (HR) recorded during recumbence and tilt. The endpoints of vasodepressor and cardioinhibitory reactions, orthostatic tachycardia, and postural tachycardia syndrome were recorded. RESULTS: Patients with FMF exhibited significantly higher diastolic BP during supine and tilt measurements (p = 0.003 and 0.04, respectively). In response to tilt, patients showed significant increases in HR compared to healthy subjects (p = 0.02). Pathological endpoints on tilt were observed in the FMF group in 7 patients (17%) and in no controls. FMF severity, genotype, duration of illness, response to therapy, and associated amyloidosis did not correlate with pathological reactions on HUTT. CONCLUSION: FMF patients exhibit an abnormal cardiovascular reactivity, which is clinically occult, but can be detected on autonomic challenge. The abnormal autonomic activity in FMF is similar to dysautonomia described in a variety of rheumatic disorders.     

The capnography head-up tilt test for evaluation of chronic fatigue syndrome

OBJECTIVES: To compare the hemodynamic and ventilatory responses to autonomic challenge evoked by upright tilt table testing in patients with chronic fatigue syndrome (CFS) to healthy individuals. METHODS: Thirty-two consecutive patients with CFS and 32 healthy volunteers were evaluated with the aid of the recently introduced capnography head-up tilt test (CHUTT). The main outcome measures were values of blood pressure (BP), heart rate (HR), respiratory rate (RR), and end-tidal pressure of co2 (ETPco2) recorded during recumbence and tilt. In addition, the end points of vasodepressor and cardioinhibitory reactions, hyperventilation (defined by ETPco2 <25 mm Hg) and the postural tachycardia syndrome, were recorded. RESULTS: The BP, HR, RR, and ETPco2 recorded during recumbence were similar in both groups. During tilt, patients with CFS developed significantly lower systolic BP, diastolic BP, and ETPco2, and a significant rise in HR and RR (P<.01). In CFS patients, the postural tachycardia syndrome occurred in 44%, vasodepressor reaction in 41%, cardioinhibitory reaction in 13%, and hyperventilation in 31% of cases. One or more end points of the CHUTT were reached in 78% of patients with CFS but in none of the controls (P<.0001). CONCLUSIONS: In most patients with CFS, a spectrum of abnormal homeostatic reactions is diagnosed with the aid of the CHUTT. Data provided by the CHUTT may reinforce the clinical diagnosis by adding objective and unbiased criteria to the subjective assessment of CFS.     

Cardiovascular haemodynamics and the response of vasopressin, aldosterone, plasma renin activity and plasma catecholamines to head-up tilt in young and old healthy subjects

Increasing age impairs the regulation of blood pressure during posture change. The neuro-humoral and cardiovascular responses to head-up tilt were analysed in carefully-screened young and healthy elderly individuals. Mean blood pressure was significantly higher in the elderly but there were no differences in total peripheral resistance, heart rate, stroke volume and cardiac index. Age-related interactions were observed in the control of mean blood pressure, heart rate and stroke volume. Total peripheral resistance increased and cardiac index decreased but there was no difference in their control in the young and old. Noradrenaline, vasopressin, plasma renin activity and aldosterone all increased in response to the tilt. These observations indicate differences in the neuroendocrine responses and cardiovascular haemodynamics of young and old healthy individuals to head-up tilt and are particularly important because of all observations were made simultaneously in the same subject. It is suggested that a similar approach should be adopted in the investigation of patients with postural hypotension.     

Effects of standing on cerebrovascular resistance in patients with idiopathic orthostatic intolerance.

PURPOSE: Patients with idiopathic orthostatic intolerance often have debilitating symptoms on standing that are suggestive of cerebral hypoperfusion despite the absence of orthostatic hypotension. SUBJECTS AND METHODS: We evaluated the effects of graded head-up tilt on cerebral blood flow as determined by transcranial Doppler measurements in 10 patients with idiopathic orthostatic intolerance (nine women, one man, 22 to 47 years) and nine age- and sex-matched control subjects. RESULTS: In patients, mean (+/- SD) arterial pressure at 0 degrees head-up tilt was 90 +/- 11 mm Hg and was well maintained at all tilt angles (90 +/- 11 mm Hg at 75 degrees). In controls, mean arterial pressure was 85 +/- 7 mm Hg at 0 degrees and 82 +/- 11 mm Hg at 75 degrees head-up tilt. There was a substantial decrease in peak velocity with increasing tilt angle in patients (28% +/- 10%) but not in controls (10% +/- 10% at 75 degrees, P <0.001). Similarly, mean velocity decreased 26% +/- 13% in patients and 12% +/- 11% in controls (P = 0.01). With increasing head-up tilt, patients had a significantly greater increase in regional cerebrovascular resistance than controls. CONCLUSIONS: In patients with idiopathic orthostatic intolerance, peak and mean middle cerebral artery blood flow velocity decreased in response to head-up tilt despite well sustained arterial blood pressure. These observations indicate that in this group of patients, regulation of cerebrovascular tone may be impaired and might therefore be a target for therapeutic interventions.     

Quantitative genetic analysis of blood pressure reactivity to orthostatic tilt using principal components analysis

Blood pressure (BP) reactivity to orthostatic tilt may be predictive of cardiovascular disease. However, the genetic and environmental influences on BP reactivity to tilt have not been well examined. Identifying different influences on BP at rest and BP during tilt is complicated by the intercorrelation among multiple measurements. In this study, we use principal components analysis (PCA) to reduce multivariate BP data into components that are orthogonal. The objective of this study is to characterize and examine the genetic architecture of BP at rest and during head-up tilt (HUT). Specifically, we estimate the heritability of individual BP measures and three principal components (PC) derived from multiple BP measurements during HUT. Additionally, we estimate covariate effects on these traits. The study sample consisted of 444 individuals, distributed across four large families. HUT consisted of 70 degrees head-up table tilting while strapped to a tilt table. BP reactivity (deltaBP) was defined as BP during HUT minus BP while supine. Three PC extracted from the PCA were interpreted as 'general BP' (PC1), 'pulse pressure' (PC2) and 'BP reactivity' (PC3). Variance components methods were used to estimate the heritabilities of resting BP, HUT BP, deltaBP, as well as the three BP PC. Significant (P<0.05) heritabilities were found for all BP measurements, except for systolic deltaBP at 1 and 3 min, and diastolic deltaBP at 2 min. Significant genetic effects were also found for the three PC. Each of these orthogonal components is significantly influenced by somewhat different sets of covariates.     

Cardiovascular response to upright tilt in fibromyalgia differs from that in chronic fatigue syndrome.

OBJECTIVE: To compare the cardiovascular response during postural challenge of patients with fibromyalgia (FM) to those with chronic fatigue syndrome (CFS). METHODS: Age and sex matched patients were studied, 38 with FM, 30 with CFS, and 37 healthy subjects. Blood pressure (BP) and heart rate (HR) were recorded during 10 min of recumbence and 30 min of head-up tilt. Differences between successive BP values and the last recumbent BP, their average, and standard deviation (SD) were calculated. Time curves of BP differences were analyzed by computer and their outline ratios (OR) and fractal dimensions (FD) were measured. HR differences were determined similarly. Based on the latter measurements, each subject's discriminant score (DS) was computed. RESULTS: For patients and controls average DS values were: FM: -3.68 (SD 2.7), CFS: 3.72 (SD 5.02), and healthy controls: -4.62 (SD 2.24). DS values differed significantly between FM and CFS (p < 0.0001). Subgroups of FM patients with and without fatigue had comparable DS values. CONCLUSION: The DS confers numerical expression to the cardiovascular response during postural challenge. DS values in FM were significantly different from DS in CFS, suggesting that homeostatic responses in FM and CFS are dissimilar. This observation challenges the hypothesis that FM and CFS share a common derangement of the stress-response system.     

Hemodynamic instability in chronic fatigue syndrome: indices and diagnostic significance.

OBJECTIVES: To evaluate the cardiovascular response to postural challenge in patients with chronic fatigue syndrome (CFS) and to determine whether the degree of instability of the cardiovascular response may aid in diagnosing CFS. METHODS: Patients with CFS (n = 25) and their age- and gender-matched healthy controls (n = 37), patients with fibromyalgia (n = 30), generalized anxiety disorder (n = 15), and essential hypertension (n = 20) were evaluated with the aid of a standardized tilt test. The blood pressure (BP) and heart rate (HR) were recorded during 10 minutes of recumbence and 30 minutes of head-up tilt. We designated BP changes as the differences between successive BP values and the last recumbent BP. The average and standard deviation (SD) were calculated. Time curves of BP differences were loaded into a computerized image analyzer, and their outline ratios and fractal dimensions were measured. HR changes were determined similarly. The average and SD of the parameters were calculated, and intergroup comparisons were performed. RESULTS: On multivariate analysis, the independent predictors of CFS patients versus healthy controls were the fractal dimension of absolute values of the systolic BP changes (SYST-FD.abs), the standard deviation of the current values of the systolic BP changes (SYST-SD.cur), and the standard deviation of the current values of the heart rate changes (HR-SD.cur). The following equation was deduced to calculate the hemodynamic instability score (HIS) in the individual patient: HIS = 64.3303 + (SYST-FD.abs x -68.0135) + (SYST-SD.cur x 111.3726) + (HR-SD.cur x 60.4164). The best cutoff differentiating CFS from the healthy controls was -0.98. HIS values >-0.98 were associated with CFS (sensitivity 97%, specificity 97%). The HIS differed significantly between CFS and other groups (P <.0001) except for generalized anxiety disorder. Group averages (SD) of HIS were CFS = +3.72 (5.02), healthy = -4.62 (2.26), fibromyalgia = -3.27 (2.63), hypertension = -5.53 (2.24), and generalized anxiety disorder = +1.08 (5.2). CONCLUSION: The HIS adds objective criteria confirming the diagnosis of CFS.     

倾斜训练对血管迷走性晕厥患者的治疗作用

目的 观察倾斜训练对血管迷走性晕厥(VVS)的治疗作用和可能机制，为采用物理方法治疗VVS提供新思路。方法 8名临床诊断为VVS且两次基础倾斜试验阳性患者，每天完成1次头高位75°的倾斜训练，连续5 d。治疗后进行基础倾斜试验，并记录试验血压、心率以及心脏泵血功能的变化。结果 倾斜训练治疗后8名患者的基础倾斜试验均转为阴性。与倾斜训练前相比，倾斜训练后平卧位时患者心率变异性低频功率、低频功率/高频功率显著升高（P<0.05），高频功率显著降低（P<0.05）；在倾斜试验终点时患者每搏量和血压显著升高（P<0.05），心率显著降低（P<0.01）。结论 每天1次、连续5 d的倾斜训练可以恢复VVS患者的立位耐力，其可能主要与改善自主神经功能、增强交感神经兴奋性和外周血管收缩能力有关。     

Distinct hemodynamic profiles in patients with vasovagal syncope: a heterogeneous population

OBJECTIVE: The objective was to investigate mechanisms of vasovagal syncope by identifying laboratory techniques that characterize cardiovascular profiles in patients with vasovagal syncope. BACKGROUND: The triggering mechanisms of vasovagal syncope are complex. The patient population is likely heterogeneous. We hypothesized that distinct hemodynamic profiles are definable with provocative maneuvers. METHODS: Three groups of subjects were matched for age and gender: 16 patients with a history of syncope and an inducible vasovagal response during passive tilt table testing (70 degrees, 45 min, group I), 16 with a history of syncope, negative passive tilt table testing but positive isoproterenol tilt table testing (0.05 microg/kg per min, 70 degrees, 10 min, group II), and 16 control subjects. Beat-to-beat hemodynamic functions were determined noninvasively by photo-plethysmography and impedance cardiography. RESULTS: At baseline, hemodynamic functions were not different among the three groups (supine). In response to tilt before any symptoms developed, total peripheral resistance decreased 9% +/- 14% in group I from baseline supine to tilt position but increased 27% +/- 18% in group II and 28% +/- 17% in controls (p < 0.001). Responses to isoproterenol were not significantly different between group II and controls in supine position. In response to tilt during isoproterenol infusion before any symptoms developed, total peripheral resistance decreased 24% +/- 20% in group II and increased 20% +/- 48% in controls (p = 0.002). CONCLUSIONS: Group I patients may have impaired ability to increase vascular resistance during orthostatic stress. The inability to overcome isoproterenol-induced vasodilatation during tilt is important in triggering a vasovagal response in group II patients. These data suggest that the population with vasovagal response is heterogeneous. Distinct hemodynamic profiles in response to various provocative maneuvers are definable with noninvasive, continuous monitoring techniques.     

The relationship between nighttime dipping in blood pressure and cerebral hemodynamics in nonstroke patients

Inadequate dipping in nighttime blood pressure (BP) is associated with cerebrovascular disease. The authors aimed to determine whether inadequate nocturnal dipping was associated with abnormalities in cerebrovascular hemodynamics in individuals without stroke. Participants in this study underwent 24-hour ambulatory BP monitoring followed by morning transcranial Doppler measurements of blood flow velocities (BFVs) in the middle cerebral artery during supine rest, head-up tilt, hypocapnia, and hypercapnia. Nighttime BP decline by <10% was considered nondipping. Of the 102 nonstroke participants (mean age, 53.6 years), 35 (34%) were dippers. Although nondippers had similar BFV and cerebrovascular resistance (CVR) while supine, they had a lower BFV (P=.04) and greater CVR (P=.02) during head-up tilt compared with dippers. Moreover, greater nighttime dipping in both systolic BP (P=.006) and diastolic BP (P=.03) were associated with higher daytime BFV and lower CVR (P=.01 for systolic BP; P=.02 for diastolic BP). Inadequate nocturnal BP dipping is associated with lower daytime cerebral blood flow, especially during head-up tilt.     

Enhanced Vagal Withdrawal During Mild Orthostatic Stress in Adolescents with Chronic Fatigue

Background: Hemodynamic abnormalities have been documented in the chronic fatigue syndrome (CFS), indicating functional disturbances of the autonomic nervous system responsible for cardiovascular regulation. The aim of this study was to investigate autonomic heart rate control during mild orthostatic stress in adolescents with CFS. Methods: A total of 14 CFS patients and 56 healthy controls having equal distribution of age and gender underwent lower body negative pressure (LBNP) of ─20 mmHg. The RR interval (RRI) was recorded continuously, and spectral power densities were computed in the low‐frequency (LF) band (0.04–0.15 Hz) and the high‐frequency (HF) band (0.15–0.50 Hz) from segments of 120‐second length, using an autoregressive algorithm. In addition, the time‐domain indices SDNN, pNN50, and r‐MSSD were computed. Results: At rest, CFS had lower RRI than controls (P < 0.05), but indices of variability were similar in the two groups. During LBNP, compared to controls, CFS patients had lower normalized and absolute HF power and r‐MSSD (P < 0.05), and higher RRI (P < 0.001), normalized LF power and LF/HF (P < 0.05). Conclusions: During mild orthostatic stress, adolescents with CFS appear to have enhanced vagal withdrawal, leading to a sympathetic predominance of heart rate control compared to controls. Possible underlying mechanisms include hypovolemia and abnormalities of reflex mechanisms.     

Beat-to-beat analysis of pressure wave morphology for pre-symptomatic detection of orthostatic intolerance during head-up tilt

OBJECTIVES: The aim of this study was to noninvasively define the hemodynamic profile characterizing the early response to tilting. BACKGROUND: The mechanisms causing orthostatic intolerance have not been fully elucidated. Usually, patients undergoing tilt test are studied in a time-consuming way. Moreover, the test can cause discomfort to the patient and even be potentially hazardous. METHODS: Nineteen orthostatic intolerant patients (OIP), compared with 22 healthy subjects (HS), performed head-up tilt test while their arterial pressure waveform was noninvasively recorded. We elaborated data using the Pressure Recording Analytical Method to obtain hemodynamic parameters, then analyzing the variables by discriminant analysis. RESULTS: Compared with HS, OIP showed lower stroke volume index (SVI) values even in baseline conditions associated with higher values of systemic vascular resistance (SVR) and heart rate (HR). From the third minute of the tilted position and until symptoms appeared, patients exhibited lower values of blood pressure (BP) and SVI and higher HR values but no difference in SVR. At termination, patients showed a further significant reduction in BP and SVI and a persistent increase in HR. CONCLUSIONS: This investigation underlines: 1) the possibility of beat-to-beat monitoring of hemodynamic changes during tilting; 2) the cardiovascular profile of OIP at rest, characterized by lower SVI and higher SVR and HR; 3) the maladaptive response to postural challenge of OIP mainly identifiable in impaired vascular regulation; and 4) the possibility of detecting parameters that enable prompt identification of the positive response to tiltingin these patients, thus guiding the duration of the test.     

Effect of various diuretic doses on hemodynamics in patients with hypertension

Before and after hypothiazide and oxodoline (chlortalidone) given in various dosages, hemodynamic parameters were examined in 132 patients with Stage II hypertensive disease at rest, in the orthostatic position, and during exercise testing on a bicycle ergometer. With either drug, a significant resting fall in systolic BP started at 25 mg, in diastolic BP at 50 mg. The hemodynamic mechanisms by which the diuretics exerted antihypertensive action were decreases in stroke index and cardiac index while specific peripheral resistance remained unchanged or slightly increased. Hypothiazide and oxodoline produced no change in orthostatic circulatory response. During bicycle ergometer testing, the absolute systolic BP value was significantly less only when hypothiazide was given in a dise of 100 mg, oxodoline--50 and 100 mg and only when exercise intensities were low (25 W). A significant drop in diastolic BP occurred only at 100 mg of oxodoline and only at low exercise intensities. The diuretics were found to have no pronounced action on the hemodynamic profile during physical exercise.     

Physiological responses to postural change in young and old healthy individuals

The cardiovascular responses to 70° head-up tilt were compared in 9 healthy young, mean age 31 ± (S.D.) 3.2 years, and 8 healthy elderly subjects, mean age 71 ± 5.1 years. After 10 minutes tilt, qualitatively similar responses were found in the two groups. Quantitatively, however, heart rate, stroke volume, cardiac output, and peripheral resistance showed smaller differences between the supine and tilt positions in the older group. Blood pressure and plasma volume changes were similar in both groups. There is an age-associated effect in the cardiovascular response to change in posture in healthy people that resembles that found in congestive cardiac failure.     

Hemodynamic reactivity to sympathoadrenal stimulation in adrenalectomized women

To determine the extent to which circulating epinephrine (E) mediates the cardiovascular effects of sympathoadrenal stimulation, we studied the blood pressure (BP), heart rate, forearm vascular resistance, and plasma catecholamine responses to a mental arithmetic test, head-up tilt test, and cold pressor test in 10 adrenalectomized women and 10 age-matched normotensive women. The mean basal diastolic BP was slightly higher in the adrenalectomized women (80 vs. 68 mm Hg; P less than 0.05). During mental arithmetic, the adrenalectomized women had a smaller heart rate increase than the normal women [6 +/- 1% (+/- SE) vs. 16 +/- 4%; P less than 0.05], but the BP response was not different. During the head-up tilt and cold pressor tests the hemodynamic responses were similar in the adrenalectomized and normal women. As expected, plasma E was undetectable in the adrenalectomized women. Plasma norepinephrine (NE) did not change in either group during mental arithmetic. In the adrenalectomized women the plasma NE increases during the head-up tilt and cold pressor test were not significantly different from those in the normal women. Thus, the adrenalectomized women had a normal pressor response during all 3 types of adrenergic stimulation, apparently independent of plasma E. Together with the normal plasma NE responses to head-up tilt and cold exposure, we challenge the contention that the E-mediated presynaptic beta-adrenergic stimulation of NE release plays a pivotal physiological role during short term adrenergic stress.     

Left ventricular filling and stress response pattern in essential hypertension

PURPOSE: To evaluate whether impaired left ventricular filling determines the hemodynamic responses to isometric and orthostatic stress in a population with mild essential hypertension. PATIENTS AND METHODS: The study population consisted of 32 patients with essential hypertension who were subdivided into those with preserved left ventricular filling (15 patients) and those with impaired left ventricular filling (17 patients). Echocardiograms were obtained before hemodynamic assessment was performed. Isometric stress and head-up tilt tests were done with a recovery period of at least 10 minutes between each to allow for blood pressure and heart rate to return to baseline. Hemodynamic reassessment was performed during the last minute of each test and at the end of the recovery period. Plasma epinephrine, norepinephrine, and dopamine levels were determined by radioenzymatic method. RESULTS: Isometric stress increased mean arterial pressure by 30% (p less than 0.0001) by an increase in cardiac output (p less than 0.0001) and total peripheral resistance (p less than 0.0001) associated with an increase in plasma catecholamine levels (p less than 0.0001). Patients with preserved left ventricular filling had an increase in arterial pressure predominantly through an elevation in cardiac output (17%, p less than 0.0001) associated with a small increase in plasma norepinephrine levels (p less than 0.05) and in peripheral resistance (11%, p less than 0.05). In contrast, patients with impaired left ventricular filling had an increase in arterial pressure mainly through an increase in peripheral resistance (25%, p less than 0.0001) that was associated with a 45% elevation in plasma norepinephrine levels (p less than 0.0001). Orthostatic stress (passive head-up tilt) caused an exaggerated decrease in stroke volume (p less than 0.01) and cardiac output (p less than 0.01) in patients with impaired left ventricular filling when compared with those with preserved diastolic function. CONCLUSION: Impaired left ventricular filling blunts the response of the heart to isometric and orthostatic stress. As a consequence, hypertensive patients with impaired ventricular filling respond to these stressors with enhanced sympathetic stimulation and exaggerated vasoconstriction.     

Hemodynamics instability score in chronic fatigue syndrome and in non-chronic fatigue syndrome

OBJECTIVE: In studying patients with chronic fatigue syndrome (CFS) we developed a method that confers numerical expression to the degree of blood pressure and heart rate lability, ie, the 'hemodynamic instability score' (HIS). The HIS in CFS patients differed significantly from healthy subjects. The present investigation compares the HIS in CFS, non-CFS chronic fatigue and patients with recurrent syncope. METHODS: Patients with CFS (n = 21), non-CFS chronic fatigue (n = 24), syncope of unknown cause (n = 44), and their age and sex-matched healthy controls (n = 21) were evaluated with a standardized head-up tilt test (HUTT). Abnormal reactions (endpoints) on HUTT were classified 'clinical outcomes' (cardioinhibitory or vasodepressor reaction, orthostatic hypotension, postural tachycardia syndrome) and 'HIS endpoint', i.e. HIS >-0.98. RESULTS: The highest incidence of endpoints was noted in patients with CFS (79%), followed by patients with syncope of unknown cause (46%), non-CFS chronic fatigue (35%), and healthy subjects (14%). Presyncope or syncope during tilt occurred in 38% of CFS patients, 21% of patients with non-CFS chronic fatigue, and 43% of patients with recurrent syncope. The average HIS values were: CFS = +2.02 (SD 4.07), non-CFS chronic fatigue = -2.89 (SD 3.64), syncope = -3.2 (SD 3.0), healthy = -2.48 (4.07). The odds ratios for CFS patients to have HIS >-0.98 was 8.8 compared with non-CFS chronic fatigue patients, 14.6 compared with recurrent syncope patients, and 34.8 compared with healthy subjects. CONCLUSION: The cardiovascular reactivity in patients with CFS has certain features in common with the reactivity in patients with recurrent syncope or non-CFS chronic fatigue, such as the frequent occurrence of vasodepressor reaction, cardioinhibitory reaction, and postural tachycardia syndrome. Apart from to these shared responses, the large majority of CFS patients exhibit a particular abnormality which is characterized by HIS values >-0.98. Thus, HIS >-0.98 lends objective criteria to the assessment of CFS.