Hypertension in orthostatic hypotension and autonomic dysfunction

Pathophysiology of syncope: current concepts and their development

Syncope is a symptom in which transient loss of consciousness occurs as a consequence of a self-limited, spontaneously terminating period of cerebral hypoperfusion. Many circulatory disturbances (e.g. brady- or tachyarrhythmias, reflex cardioinhibition-vasodepression-hypotension) may trigger a syncope or near-syncope episode, and identifying the cause(s) is often challenging. Some syncope may involve multiple etiologies operating in concert, whereas in other cases multiple syncope events may be due to various differing causes at different times. In this communication, we address the current understanding of the principal contributors to syncope pathophysiology including examination of the manner in which concepts evolved, an overview of factors that constitute consciousness and loss of consciousness, and aspects of neurovascular control and communication that are impacted by cerebral hypoperfusion leading to syncope. Emphasis focuses on 1) current understanding of the way transient systemic hypotension impacts brain blood flow and brain function; 2) the complexity and temporal sequence of vascular, humoral, and cardiac factors that may accompany the most common causes of syncope; 3) the range of circumstances and disease states that may lead to syncope; and 4) clinical features associated with syncope and in particular the reflex syncope syndromes.

Effects of Atomoxetine for the Treatment of Neurogenic Orthostatic Hypotension in Patients With Alpha-synucleinopathies: A Systematic Review of Randomized Controlled Trials and a Focus-Group Discussion

BACKGROUND AND PURPOSE

Neurogenic orthostatic hypotension (nOH) is one of the most important nonmotor symptoms in patients with α-synucleinopathies. Atomoxetine is a selective norepinephrine transporter blocker that is a treatment option for nOH. This systematic review and expert focus-group study was designed to obtain evidence from published data and clinical experiences of Korean movement-disorder specialists about the efficacy and safety of atomoxetine for the pharmacological treatment of nOH in patients with α-synucleinopathies.

METHODS

The study comprised a systematic review and a focus-group discussion with clinicians. For the systematic review, multiple comprehensive databases including MEDLINE, Embase, Cochrane Library, CINAHL, PsycInfo, and KoreaMed were searched to retrieve articles that assessed the outcomes of atomoxetine therapy. A focus-group discussion was additionally performed to solicit opinions from experts with experience in managing nOH.

RESULTS

The literature review process yielded only four randomized controlled trials on atomoxetine matching the inclusion criteria. Atomoxetine effectively increased systolic blood pressure and improved OH-related symptoms as monotherapy or in combination with other drugs. Its effects were pronounced in cases with central autonomic failure, including multiple-system atrophy (MSA). Atomoxetine might be a safe monotherapy regarding the risk of supine hypertension.

CONCLUSIONS

Atomoxetine is an effective and safe option for short-term nOH management, which could be more evident in patients with central autonomic dysfunction such as MSA. However, there is a paucity of evidence in the literature, and data from the focus-group discussion were inadequate, and so further investigation is warranted.

Ageing and the Autonomic Nervous System

The vertebrate nervous system is divided into central (CNS) and peripheral (PNS) components. In turn, the PNS is divided into the autonomic (ANS) and enteric (ENS) nervous systems. Ageing implicates time-related changes to anatomy and physiology in reducing organismal fitness. In the case of the CNS, there exists substantial experimental evidence of the effects of age on individual neuronal and glial function. Although many such changes have yet to be experimentally observed in the PNS, there is considerable evidence of the role of ageing in the decline of ANS function over time. As such, this chapter will argue that the ANS constitutes a paradigm for the physiological consequences of ageing, as well as for their clinical implications.

Autonomic failure: Clinicopathologic, physiologic, and genetic aspects

Over the past century, generations of neuroscientists, pathologists, and clinicians have elucidated the underlying causes of autonomic failure found in neurodegenerative, inherited, and antibody-mediated autoimmune disorders, each with pathognomonic clinicopathologic features. Autonomic failure affects central autonomic nervous system components in the α-synucleinopathy, multiple system atrophy, characterized clinically by levodopa-unresponsive parkinsonism or cerebellar ataxia, and pathologically by argyrophilic glial cytoplasmic inclusions (GCIs). Two other central neurodegenerative disorders, pure autonomic failure characterized clinically by deficits in norepinephrine synthesis and release from peripheral sympathetic nerve terminals; and Parkinson's disease, with early and widespread autonomic deficits independent of the loss of striatal dopamine terminals, both express Lewy pathology. The rare congenital disorder, hereditary sensory, and autonomic neuropathy type III (or Riley-Day, familial dysautonomia) causes life-threatening autonomic failure due to a genetic mutation that results in loss of functioning baroreceptors, effectively separating afferent mechanosensing neurons from the brain. Autoimmune autonomic ganglionopathy caused by autoantibodies targeting ganglionic α3-acetylcholine receptors instead presents with subacute isolated autonomic failure affecting sympathetic, parasympathetic, and enteric nervous system function in various combinations. This chapter is an overview of these major autonomic disorders with an emphasis on their historical background, neuropathological features, etiopathogenesis, diagnosis, and treatment.

Utricular dysfunction in patients with orthostatic hypotension

PURPOSE

To delineate the association between otolithic dysfunction and orthostatic hypotension (OH).

METHODS

We retrospectively reviewed the medical records of 382 patients who presented with orthostatic dizziness at a tertiary dizziness center between July 2017 and December 2021. Patients were included for analyses when they had completed ocular (oVEMP) and/or cervical vestibular-evoked myogenic potentials (cVEMP), and head-up tilt table test with a Finometer (n = 155). We compared the results between the patients with OH (n = 38) and those with NOI (normal head-up tilt table test despite orthostatic intolerance, n = 117).

RESULTS

Thirty-eight patients with OH were further categorized as either classic (n = 30), delayed (n = 7), or initial (n = 1) types. Multivariable logistic regression showed that OH was associated with high baseline systolic BP (p = 0.046), presence of heart failure (p = 0.016), and unilateral oVEMP abnormalities (p = 0.016). n1 latency of oVEMP were negatively correlated with the maximal changes of systolic blood pressure (BP) in 15 s ([Formula: see text]SBP_15s, p = 0.013), 3 min ([Formula: see text]SBP_3min, p = 0.005) and 10 min ([Formula: see text]SBP_10min, p = 0.002). In contrast, the n1-p1 amplitude was positively correlated with [Formula: see text]SBP_15s (p = 0.029). Meanwhile, p13 latency of cVEMP was negatively correlated with [Formula: see text]SBP_10min (p = 0.018).

CONCLUSIONS

Our study provides evidence of utricular dysfunction related to OH.

Hypertension depresses arterial baroreflex control of both heart rate and cardiac output during rest, exercise, and metaboreflex activation

Rapid regulation of arterial blood pressure on a beat-by-beat basis occurs primarily via arterial baroreflex control of cardiac output (CO) via rapid changes in heart rate (HR). Previous studies have shown that changes in HR do not always cause changes in CO, because stroke volume may vary. Whether these relationships are altered in hypertension is unknown. Using the spontaneous baroreflex sensitivity (SBRS) approach, we investigated whether baroreflex control of HR and CO were impaired after the induction of hypertension in conscious, chronically instrumented canines at rest, during mild exercise, and during exercise with metaboreflex activation (induced via reductions in hindlimb blood flow) both before and after induction of hypertension (induced via a modified Goldblatt approach-unilateral reduction in renal blood flow to ∼30% of control values until systolic pressure ≥ 140 mmHg and a diastolic pressure ≥ 90 mmHg for >30 days). After induction of hypertension, SBRS control of both HR and CO was reduced in all settings. In control, only about 50% of SBRS changes in HR caused changes in CO. This pattern was sustained in hypertension. Thus, in hypertension, the reduced SBRS in the control of HR caused reduced SBRS control of CO and this likely contributes to the increased incidence of orthostatic hypotension seen in hypertensive patients.

Pure Autonomic Failure-A Localized Alpha Synucleinopathy with a Potential for Conversion to More Extensive Alpha Synucleinopathies

Pure autonomic failure (PAF) is an alpha synucleinopathy with predominant involvement of the autonomic ganglia and peripheral nerves. The hallmark clinical feature is orthostatic hypotension. However, genitourinary, sudomotor, and cardiac involvement is also common. Many patients also develop supine hypertension. Almost a quarter of patients can phenoconvert or evolve into Parkinson's disease, multiple system atrophy, and Lewy body dementia in the future. Early severe bladder involvement, higher supine noradrenaline level, early motor involvement, and dream enactment behavior increase the risk of phenoconversion. The diagnosis is confirmed via autonomic function testing and serum noradrenaline measurement. The treatment is mainly supportive. The non-pharmacological treatment includes adequate fluid, dietary salt, compression stockings, and abdominal binders. The drug therapies to improve blood pressure include midodrine, fludrocortisone, pyridostigmine, and droxidopa. The diagnostic criteria need to be updated to incorporate the recent understandings. The treatment of orthostatic hypotension and supine hypertension is mainly based on case series and anecdotal reports. Randomized control trials are needed to ascertain the best treatment strategies for PAF.

Advances in the Pathophysiology and Management of Supine Hypertension in Patients with Neurogenic Orthostatic Hypotension

PURPOSE OF REVIEW

Patients with neurogenic orthostatic hypotension (OH) frequently have hypertension in the supine position (sHTN). We review the controversies surrounding the need and safety of treating sHTN in patients with OH.

RECENT FINDINGS

The presence of sHTN complicates the management of OH because treatment of one can worsen the other. New approaches have been developed to treat OH without worsening sHTN by preferentially improving standing blood pressure, such as medications that harness the patient's residual sympathetic tone like pyridostigmine and atomoxetine, and devices such as an automated abdominal binder that targets the inappropriate splanchnic venous pooling causing OH. There is a reluctance to treat sHTN for fear of increasing the risks of falls and syncope associated with OH, thought to be more immediate and dangerous than the late complications of organ damage associated with sHTN. This, however, does not take into account that nighttime sHTN induces natriuresis, volume loss, and begets daytime orthostatic hypotension. It is possible to treat sHTN in ways that reduce the risk of worsening OH. Furthermore, novel approaches, such as the use of local heat can control nighttime sHTN, reduce nocturia, and improve OH. Although continued progress is needed, recent findings offer hope that we can treat nocturnal sHTN and at the same time improve daytime OH, lessening the controversy whether to treat or not sHTN.

The Pathogenesis and Treatment of Cardiovascular Autonomic Dysfunction in Parkinson's Disease: What We Know and Where to Go

Cardiovascular autonomic dysfunctions (CAD) are prevalent in Parkinson’s disease (PD). It contributes to the development of cognitive dysfunction, falls and even mortality. Significant progress has been achieved in the last decade. However, the underlying mechanisms and effective treatments for CAD have not been established yet. This review aims to help clinicians to better understand the pathogenesis and therapeutic strategies. The literatures about CAD in patients with PD were reviewed. References for this review were identified by searches of PubMed between 1972 and March 2021, with the search term “cardiovascular autonomic dysfunctions, postural hypotension, orthostatic hypotension (OH), supine hypertension (SH), postprandial hypotension, and nondipping”. The pathogenesis, including the neurogenic and non-neurogenic mechanisms, and the current pharmaceutical and non-pharmaceutical treatment for CAD, were analyzed. CAD mainly includes four aspects, which are OH, SH, postprandial hypotension and nondipping, among them, OH is the main component. Both non-neurogenic and neurogenic mechanisms are involved in CAD. Failure of the baroreflex circulate, which includes the lesions at the afferent, efferent or central components, is an important pathogenesis of CAD. Both non-pharmacological and pharmacological treatment alleviate CAD-related symptoms by acting on the baroreflex reflex circulate. However, pharmacological strategy has the limitation of failing to enhance baroreflex sensitivity and life quality. Novel OH treatment drugs, such as pyridostigmine and atomoxetine, can effectively improve OH-related symptoms via enhancing residual sympathetic tone, without adverse reactions of supine hypertension. Baroreflex impairment is a crucial pathological mechanism associated with CAD in PD. Currently, non-pharmacological strategy was the preferred option for its advantage of enhancing baroreflex sensitivity. Pharmacological treatment is a second-line option. Therefore, to find drugs that can enhance baroreflex sensitivity, especially via acting on its central components, is urgently needed in the scientific research and clinical practice.

A review of cardiac autonomics: from pathophysiology to therapy

The effective management of cardiovascular diseases requires knowledge of intrinsic and extrinsic innervation of the heart and an understanding of how perturbations of said components affect cardiac function. The innate cardiac conduction system, which begins with cardiac pacemaker cells and terminates with subendocardial Purkinje fibers, is modulated by said systems. The intrinsic component of the cardiac autonomic nervous system, which remains incompletely elucidated, consists of intracardiac ganglia and interconnecting neurons that tightly regulate cardiac electrical activity. Extrinsic components of the autonomic nervous system, such as carotid baroreceptors and renin-angiotensin-aldosterone system, modulate sympathetic input to the heart through the stellate ganglion and parasympathetic input via the vagus nerve. There remains a need for additional therapies to treat conditions, such as advanced heart failure and refractory arrhythmias, and a better understanding of autonomics may be key to their development.

Initial orthostatic hypotension and orthostatic intolerance symptom prevalence in older adults: A systematic review

Background

Initial orthostatic hypotension is a clinically relevant syndrome in older adults which has been associated with symptoms of orthostatic intolerance. The aim of this systematic review was to determine the prevalence of orthostatic intolerance symptoms in older adults with initial orthostatic hypotension.

Methods

MEDLINE (from 1946), EMBASE (from 1974) and Cochrane were searched to December 6th^, 2019 using the terms "initial orthostatic hypotension", "postural hypotension" and "older adults". Study selection involved the following criteria: published in English; mean or median age ≥ 65 years and diagnosis of initial orthostatic hypotension encompassed a decrease in systolic blood pressure by ≥ 40  mmHg and/or diastolic blood pressure by ≥ 20  mmHg within a maximum of 1 min following a postural change.

Results

Of 8311 articles, 12 articles reporting initial orthostatic hypotension prevalence in 3446 participants with a mean age of 75 (6 SD) years (56.5% female) were included. Five initial orthostatic hypotension definition variations were utilised and symptoms were reported in six articles (968 participants, mean age 73.4 (6.1 SD) years, 56% female). The prevalence of symptoms in older adults with initial orthostatic hypotension ranged from 24 to 100% and was dependent on variations in timing or the inclusion of symptoms in the initial orthostatic hypotension definition.

Conclusions

Where orthostatic intolerance symptoms were reported, a large proportion of older adults with a diagnosis of initial orthostatic hypotension were symptomatic. However, the literature on initial orthostatic hypotension and orthostatic intolerance symptoms is scarce and a variety of definitions of initial orthostatic hypotension are utilised.

Syndrome of Supine Hypertension with Orthostatic Hypotension: Pathophysiology and Clinical Approach

This article is intended to provide guidance and clinical considerations for physicians managing patients suffering from supine hypertension with orthostatic hypotension, referred to as “SH-OH”. We review the normal physiologic response to orthostasis, focusing on the appropriate changes to autonomic output in this state. Autonomic failure is discussed with a generalized overview of the disease and examination of specific syndromes that help shed light on the pathophysiology of SH-OH. The goal of this review is to provide a better framework for clinical evaluation of these patients, review treatment options, and ultimately work toward achieving a better quality of life for patients afflicted with this disease.

Droxidopa for the treatment of neurogenic orthostatic hypotension in neurodegenerative diseases

INTRODUCTION

L-threo-3,4-dihydroxyphenylserine (droxidopa), a pro-drug metabolized to norepinephrine in nerve endings and other tissues, has been commercially available in Japan since 1989 for treating orthostatic hypotension symptoms in Parkinson's disease (PD) patients with a Hoehn & Yahr stage III rating, as well as patients with Multiple System Atrophy (MSA), familial amyloid polyneuropathy, and hemodialysis. Recently, the FDA has approved its use in symptomatic neurogenic orthostatic hypotension (NOH). Areas covered: The authors review the effects of droxidopa in NOH with a focus on the neurodegenerative diseases PD, MSA, and pure autonomic failure (PAF). Expert opinion: A few small and short placebo-controlled clinical trials in NOH showed significant reductions in the manometric drop in blood pressure (BP) after posture changes or meals. Larger Phase III studies showed conflicting results, with two out of four trials meeting their primary outcome and thus suggesting a positive yet short-lasting effect of the drug on OH Questionnaire composite score, light-headedness/dizziness score, and standing BP during the first two treatment-weeks. Results appear essentially similar in PD, MSA, and PAF. The FDA granted droxidopa approval in the frame of an 'accelerated approval program' provided further studies are conducted to assess its long-term effects on OH symptoms.

Pure Autonomic Failure with Asymptomatic Hypertensive Urgency: A Case Report and Literature Review

We report the case study of a 70-year-old gentleman who presented with isolated, slowly progressive dizziness after prolonged standing and was eventually diagnosed with pure autonomic failure. Initially, his symptoms improved with the use of midodrine and fludrocortisone, but gradually became refractory and disabling. Despite multiple therapeutic interventions, his symptoms persisted along with worsening supine hypertension. We discuss the challenges faced in the treatment of an uncommon condition and discuss the clinical utility of performing serial 24-h ambulatory monitoring to detect subclinical blood pressure fluctuations.

Consensus statement on the definition of neurogenic supine hypertension in cardiovascular autonomic failure by the American Autonomic Society (AAS) and the European Federation of Autonomic Societies (EFAS) : Endorsed by the European Academy of Neurology (EAN) and the European Society of Hypertension (ESH)

PURPOSE

Patients suffering from cardiovascular autonomic failure often develop neurogenic supine hypertension (nSH), i.e., high blood pressure (BP) in the supine position, which falls in the upright position owing to impaired autonomic regulation. A committee was formed to reach consensus among experts on the definition and diagnosis of nSH in the context of cardiovascular autonomic failure.

METHODS

As a first and preparatory step, a systematic search of PubMed-indexed literature on nSH up to January 2017 was performed. Available evidence derived from this search was discussed in a consensus expert round table meeting in Innsbruck on February 16, 2017. Statements originating from this meeting were further discussed by representatives of the American Autonomic Society and the European Federation of Autonomic Societies and are summarized in the document presented here. The final version received the endorsement of the European Academy of Neurology and the European Society of Hypertension.

RESULTS

In patients with neurogenic orthostatic hypotension, nSH is defined as systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg, measured after at least 5 min of rest in the supine position. Three severity degrees are recommended: mild, moderate and severe. nSH may also be present during nocturnal sleep, with reduced-dipping, non-dipping or rising nocturnal BP profiles with respect to mean daytime BP values. Home BP monitoring and 24-h-ambulatory BP monitoring provide relevant information for a customized clinical management.

CONCLUSIONS

The establishment of expert-based criteria to define nSH should standardize diagnosis and allow a better understanding of its epidemiology, prognosis and, ultimately, treatment.

Blood pressure management in older people: balancing the risks

Guidelines of arterial hypertension treatment based on individualised expected outcomes are not available for frail older persons. In this paper, we review the evidence, concerning management of arterial blood pressure (BP) in frail older patients. We focused on the best affordable methods for BP measurement; the age-related optimum BP; specific BP goals in agreement with the patients' general heath, frailty status, orthostatic and postprandial hypotension; balancing the benefits against risks of antihypertensive treatment. Lenient BP goals are generally recommended for older persons with moderate or severe frailty, multimorbidity and limited life expectancy. To this aim, there may be a need for deintensification of antihypertensive treatment.

Pharmacotherapy of Cardiovascular Autonomic Dysfunction in Parkinson Disease

Cardiovascular autonomic dysfunctions, including neurogenic orthostatic hypotension, supine hypertension and post-prandial hypotension, are relatively common in patients with Parkinson disease. Recent evidence suggests that early autonomic impairment such as cardiac autonomic denervation and even neurogenic orthostatic hypotension occur prior to the appearance of the typical motor deficits associated with the disease. When neurogenic orthostatic hypotension develops, patients with Parkinson disease have an increased risk of mortality, falls, and trauma-related to falls. Neurogenic orthostatic hypotension reduces quality of life and contributes to cognitive decline and physical deconditioning. The co-existence of supine hypertension complicates the treatment of neurogenic orthostatic hypotension because it involves the use of drugs with opposing effects. Furthermore, treatment of neurogenic orthostatic hypotension is challenging because of few therapeutic options; in the past 20 years, the US Food and Drug Administration approved only two drugs for the treatment of this condition. Small, open-label or randomized studies using acute doses of different pharmacologic probes suggest benefit of other drugs as well, which could be used in individual patients under close monitoring. This review describes the pathophysiology of neurogenic orthostatic hypotension and supine hypertension in Parkinson disease. We discuss the mode of action and therapeutic efficacy of different pharmacologic agents used in the treatment of patients with cardiovascular autonomic failure.

Pure autonomic failure

Pure autonomic failure is a degenerative disorder of the peripheral autonomic nervous system. Patients experience symptomatic hypotension that requires them to sit, squat or lie down to prevent syncope. It is associated with characteristic histopathological findings, resulting in neuronal cytoplasmic inclusions in the peripheral autonomic nerves. These lesions are responsible for defects in the synthesis and release of norepinephrine from sympathetic nerve terminals, resulting in significant hypotension. Patients with autonomic failure also have exaggerated blood pressure responses to common stimuli such as food or fluid intake, heat, exercise and medications. Tilt table (head-up) testing is probably the test most commonly used to establish the diagnosis. However, simple office testing is also useful, such as having the patient stand after lying supine with blood pressure monitoring. Treatment options range from simply increasing fluid and salt intake, and using compressive garments, to medications administered orally, subcutaneously or intravenously in more severe cases.

Orthostatic Circulatory Disorders: From Nosology to Nuts and Bolts

When patients complain of altered consciousness or discomfort in the upright posture, either relieved by recumbency or culminating in syncope, physicians may find themselves baffled. There is a wide variety of disorders that cause abnormal regulation of blood pressure and pulse rate in the upright posture. The aim of this focused review is 3-fold. First, to offer a classification (nosology) of these disorders; second, to illuminate the mechanisms that underlie them; and third, to assist the physician in the practical aspects of diagnosis of adult orthostatic hypotension, by extending clinical skills with readily available office technology.

New insights into orthostatic hypotension in multiple system atrophy: a European multicentre cohort study

OBJECTIVES

Orthostatic hypotension (OH) is a key feature of multiple system atrophy (MSA), a fatal progressive neurodegenerative disorder associated with autonomic failure, parkinsonism and ataxia. This study aims (1) to determine the clinical spectrum of OH in a large European cohort of patients with MSA and (2) to investigate whether a prolonged postural challenge increases the sensitivity to detect OH in MSA.

METHODS

Assessment of OH during a 10 min orthostatic test in 349 patients with MSA from seven centres of the European MSA-Study Group (age: 63.6 ± 8.8 years; disease duration: 4.2 ± 2.6 years). Assessment of a possible relationship between OH and MSA subtype (P with predominant parkinsonism or C with predominant cerebellar ataxia), Unified MSA Rating Scale (UMSARS) scores and drug intake.

RESULTS

187 patients (54%) had moderate (> 20 mm Hg (systolic blood pressure (SBP)) and/or > 10 mm Hg (diastolic blood pressure (DBP)) or severe OH (> 30 mm Hg (SBP) and/or > 15 mm Hg (DBP)) within 3 min and 250 patients (72%) within 10 min. OH magnitude was significantly associated with disease severity (UMSARS I, II and IV), orthostatic symptoms (UMSARS I) and supine hypertension. OH severity was not associated with MSA subtype. Drug intake did not differ according to OH magnitude except for antihypertensive drugs being less frequently, and antihypotensive drugs more frequently, prescribed in severe OH.

CONCLUSIONS

This is the largest study of OH in patients with MSA. Our data suggest that the sensitivity to pick up OH increases substantially by a prolonged 10 min orthostatic challenge. These results will help to improve OH management and the design of future clinical trials.

Effect of orthostatic hypotension on sustained attention in patients with autonomic failure

INTRODUCTION

Orthostatic hypotension has been associated with impaired cognitive function, but cognitive function during orthostatic hypotension has hardly been studied. We studied the effect of orthostatic hypotension, induced by head-up tilt (HUT), on sustained attention in patients with autonomic failure.

METHODS

We studied the sustained attention to response task (SART) in the supine position and during HUT in 10 patients with autonomic failure and 10 age-matched and sex-matched controls. To avoid syncope, the tilting angle was tailored to patients to reach a stable systolic blood pressure below 100 mm Hg. Controls were all tilted at an angle of 60°. Cerebral blood flow velocity, blood pressure and heart rate were measured continuously.

RESULTS

In patients, systolic blood pressure was 61.4 mm Hg lower during HUT than in the supine position (p<0.001). Patients did not make more SART errors during HUT than in the supine position (-1.3 errors, p=0.3). Controls made 2.3 fewer errors during SART in the HUT position compared to the supine position (p=0.020). SART performance led to an increase in systolic blood pressure (+11.8 mm Hg, p=0.018) and diastolic blood pressure (+5.8 mm Hg, p=0.017) during SART in the HUT position, as well as to a trend towards increased cerebral blood flow velocity (+3.8 m/s, p=0.101).

DISCUSSION

Orthostatic hypotension in patients with autonomic failure was not associated with impaired sustained attention. This might partly be explained by the observation that SART performance led to a blood pressure increase. Moreover, the upright position was associated with better performance in controls and, to a lesser extent, also in patients.

Supine hypertension in Parkinson's disease and multiple system atrophy

OBJECTIVE

Supine hypertension (SH) is a feature of cardiovascular autonomic failure that often accompanies orthostatic hypotension and may represent a negative prognostic factor in parkinsonian syndromes. Here we investigated the frequency rate as well as the clinical and tilt test correlates of SH in Parkinson's disease (PD) and multiple system atrophy (MSA).

METHODS

197 PD (33 demented) and 78 MSA (24 MSA-Cerebellar, 54 MSA-Parkinsonian) patients who had undergone a tilt test examination were retrospectively included. Clinical-demographic characteristics were collected from clinical records at the time of the tilt test examination.

RESULTS

SH (>140 mmHg systolic, >90 mmHg diastolic) occurred in 34 % of PD patients (n = 66, mild in 71 % of patients, moderate in 27 %, severe in 2 %) and 37 % of MSA ones (n = 29, mild in 55 % of patients, moderate in 17 %, severe in 28 %). No difference was observed in SH frequency between demented versus gender-, age- and disease duration-matched non-demented PD patients, or between patients with the parkinsonian (MSA-P) versus the cerebellar (MSA-C) variant of MSA. In PD, SH was associated with presence of cardiovascular comorbidities (p = 0.002) and greater systolic (p = 0.007) and diastolic (p = 0.002) orthostatic blood pressure fall. Orthostatic hypotension (p = 0.002), and to a lesser degree, lower daily dopaminergic intake (p = 0.01) and use of anti-hypertensive medications (p = 0.04) were associated with SH in MSA.

INTERPRETATION

One-third of PD and MSA patients suffer from mild to severe SH, independently of age, disease duration or stage. In PD, cardiovascular comorbidities significantly contribute to the development of SH, while in MSA, SH appears to reflect cardiovascular autonomic failure.

Mineralocorticoid Receptor Activation Contributes to the Supine Hypertension of Autonomic Failure

Primary autonomic failure is characterized by disabling orthostatic hypotension, but at least half of these patients have paradoxical supine hypertension. Renin-angiotensin mechanisms were not initially thought to contribute to this hypertension because plasma renin activity is often undetectable in autonomic failure. Plasma aldosterone levels are normal, however, and we recently showed that plasma angiotensin II is elevated and acts at AT1 (angiotensin type 1) receptors to contribute to hypertension in these patients. Because aldosterone and angiotensin II can also bind mineralocorticoid receptors to elevate blood pressure, we hypothesized that mineralocorticoid receptor activation plays a role in the hypertension of autonomic failure. To test this hypothesis, we determined the acute effects of the mineralocorticoid receptor antagonist eplerenone (50 mg, oral) versus placebo on supine blood pressure in a randomized, double-blind, crossover study. Medications were given at 8:00 pm with blood pressure recorded every 2 hours for 12 hours. Ten primary autonomic failure patients with supine hypertension completed this study (7 pure autonomic failure, 2 multiple system atrophy, 1 parkinson's disease; 7 male; 70±2 years of age). Eplerenone maximally reduced supine systolic blood pressure by 32±6 mm Hg at 8 hours after administration (versus 8±10 mm Hg placebo, P=0.016), with no effect on nocturia (12-hour urine volume: 985±134 mL placebo versus 931±94 mL eplerenone, P=0.492; nocturnal weight loss: -1.19±0.15 kg placebo versus -1.18±0.15 kg eplerenone, P=0.766). These findings suggest that inappropriate mineralocorticoid receptor activation contributes to the hypertension of autonomic failure, likely independent of canonical mineralocorticoid effects, and provides rationale for use of eplerenone in these patients.

Clinical characteristics of supine hypertension in de novo Parkinson disease

PURPOSE

Supine hypertension is frequently associated with autonomic failure. However, its clinical characteristics in patients with Parkinson disease (PD) remain unclear. The present study aimed to clarify the characteristics of supine hypertension in patients with de novo PD.

METHODS

The subjects were 72 patients with de novo PD. We studied blood pressure and plasma norepinephrine levels after the patients rested for 20 min in the supine position. Changes in blood pressure were also examined on head-up tilt-table testing.

RESULTS

The disease duration was 1.7 ± 1.6 years (average ± SD). Thirty-three (45.8 %) patients had supine hypertension (defined as a blood pressure of ≥140/90 mmHg). Supine blood pressure positively correlated with the degree of orthostatic hypotension. Age and the proportion of patients with akinetic-rigid motor subtype or preexisting hypertension were higher among patients with supine hypertension than among those without supine hypertension. The Mini-Mental State Examination score was lower in patients with supine hypertension than in those without supine hypertension. Sex, disease duration, disease severity, and peripheral sympathetic nervous activity as evaluated by the cardiac uptake of (123)I-metaiodobenzylguanidine and the plasma norepinephrine level did not differ between patients with and those without supine hypertension.

CONCLUSION

Older age, akinetic-rigid motor subtype, and preexisting hypertension are independent risk factors for supine hypertension. Supine hypertension alone may be associated with milder peripheral sympathetic nervous denervation than orthostatic hypotension alone. As for global cognitive decline, supine hypertension is a far riskier comorbidity of early-stage PD than is orthostatic hypotension.

Dysautonomia in Parkinson disease

Dysautonomias are conditions in which altered function of one or more components of the autonomic nervous system (ANS) adversely affects health. This review updates knowledge about dysautonomia in Parkinson disease (PD). Most PD patients have symptoms or signs of dysautonomia; occasionally, the abnormalities dominate the clinical picture. Components of the ANS include the sympathetic noradrenergic system (SNS), the parasympathetic nervous system (PNS), the sympathetic cholinergic system (SCS), the sympathetic adrenomedullary system (SAS), and the enteric nervous system (ENS). Dysfunction of each component system produces characteristic manifestations. In PD, it is cardiovascular dysautonomia that is best understood scientifically, mainly because of the variety of clinical laboratory tools available to assess functions of catecholamine systems. Most of this review focuses on this aspect of autonomic involvement in PD. PD features cardiac sympathetic denervation, which can precede the movement disorder. Loss of cardiac SNS innervation occurs independently of the loss of striatal dopaminergic innervation underlying the motor signs of PD and is associated with other nonmotor manifestations, including anosmia, REM behavior disorder, orthostatic hypotension (OH), and dementia. Autonomic dysfunction in PD is important not only in clinical management and in providing potential biomarkers but also for understanding disease mechanisms (e.g., autotoxicity exerted by catecholamine metabolites). Since Lewy bodies and Lewy neurites containing alpha-synuclein constitute neuropathologic hallmarks of the disease, and catecholamine depletion in the striatum and heart are characteristic neurochemical features, a key goal of future research is to understand better the link between alpha-synucleinopathy and loss of catecholamine neurons in PD.

Nebivolol, but not metoprolol, lowers blood pressure in nitric oxide-sensitive human hypertension

Nebivolol, unlike other selective β1-receptor blockers, induces vasodilation attributable to increased NO bioavailability. The relative contribution of this mechanism to the blood pressure (BP)-lowering effects of nebivolol is unclear because it is normally masked by baroreflex buffering. Autonomic failure provides a unique model of hypertension devoid of autonomic modulation but sensitive to the hypotensive effects of NO potentiation. We tested the hypothesis that nebivolol would decrease BP in these patients through a mechanism independent of β-blockade. We randomized 20 autonomic failure patients with supine hypertension (14 men; 69±2 years) to receive a single oral dose of placebo, nebivolol 5 mg, metoprolol 50 mg (negative control), and sildenafil 25 mg (positive control) on separate nights in a double-blind, crossover study. Supine BP was monitored every 2 hours from 8:00 pm to 8:00 am. Compared with placebo, sildenafil and nebivolol decreased systolic BP during the night (P<0.001 and P=0.036, by mixed-effects model, maximal systolic BP reduction 8-hour postdrug of -20±6 and -24±9 mm Hg, respectively), whereas metoprolol had no effect. In a subanalysis, we divided patients into sildenafil responders (BP fall>20 mm Hg at 4:00 am) and nonresponders. Nebivolol significantly lowered systolic BP in sildenafil responders (-44±13 mm Hg) but not in nonresponders (1±11 mm Hg). Despite lowering nighttime BP, nebivolol did not worsen morning orthostatic tolerance compared with placebo. In conclusion, nebivolol effectively lowered supine hypertension in autonomic failure, independent of β1-blockade. These results are consistent with the hypothesis that NO potentiation contributes significantly to the antihypertensive effect of nebivolol.

Combination ergotamine and caffeine improves seated blood pressure and presyncopal symptoms in autonomic failure

Severely affected patients with autonomic failure require pressor agents to counteract the blood pressure fall and improve presyncopal symptoms upon standing. Previous studies suggest that combination ergotamine and caffeine may be effective in the treatment of autonomic failure, but the efficacy of this drug has not been evaluated in controlled trials. Therefore, we compared the effects of ergotamine/caffeine on seated blood pressure and orthostatic tolerance and symptoms in 12 primary autonomic failure patients without history of coronary artery disease. Patients were randomized to receive a single oral dose of placebo, midodrine (5–10 mg), or ergotamine and caffeine (1 and 100 mg, respectively) in a single-blind, crossover study. Blood pressure was measured while patients were seated and after standing for up to 10 min, at baseline and at 1 h post-drug. Ergotamine/caffeine increased seated systolic blood pressure (SBP), the primary outcome, compared with placebo (131 ± 19 and 95 ± 12 mmHg, respectively, at 1 h post-drug; p = 0.003 for time effect). Midodrine also significantly increased seated SBP (121 ± 19 mmHg at 1 h post-drug; p = 0.015 for time effect vs. placebo), but this effect was not different from ergotamine/caffeine (p = 0.621). There was no significant effect of either medication on orthostatic tolerance; however, ergotamine/caffeine improved presyncopal symptoms (p = 0.034). These findings suggest that combination ergotamine and caffeine elicits a seated pressor response that is similar in magnitude to midodrine, and improves symptoms in autonomic failure. Thus, ergotamine/caffeine could be used as an alternate treatment for autonomic failure, in carefully selected patients without comorbid coronary artery disease.

Carotid artery thickening and neurocirculatory abnormalities in de novo Parkinson disease

Cognitive dysfunction constitutes a major non-motor manifestation of Parkinson disease (PD), but the mechanisms remain incompletely understood. Neurocirculatory abnormalities such as supine hypertension (SH) and orthostatic hypotension (OH), white matter hyperintensities upon magnetic resonance imaging, and dementia are inter-related in PD, even in patients with early, levodopa-untreated disease. These abnormalities might in turn be associated with carotid atherosclerosis which, by a variety of interacting means could contribute to repeated episodes of cerebral hypo- and hyper-perfusion. We investigated inter-correlations among neurocirculatory and carotid sonographic measurements [intimal-medial thickness (IMT) and wall:lumen ratios (WLR)] in 65 patients with levodopa-untreated, de novo PD who underwent tilt table testing and 24-h ambulatory blood pressure monitoring. Increased mean IMT and WLR were associated with OH and supine and overnight blood pressures. Across individuals the orthostatic fall in systolic pressure was correlated with both IMT and WLR. Since arteriosclerosis would be expected to splint carotid sinus baroreceptors, complex positive interactions among carotid wall thickening, SH, and OH may result in myriad episodes of cerebral hypo- and hyper-perfusion, contributing to microvascular injury and consequently to the cognitive dysfunction attending PD.

Current concepts in orthostatic hypotension management

Orthostatic hypotension is a condition commonly affecting the elderly and is often accompanied by disabling presyncopal symptoms, syncope and impaired quality of life. The pathophysiology of orthostatic hypotension is linked to abnormal blood pressure regulatory mechanisms and autonomic insufficiency. As part of its diagnostic evaluation, a comprehensive history and medical examination focused on detecting symptoms and physical findings of autonomic neuropathy should be performed. In individuals with substantial falls in blood pressure upon standing, autonomic function tests are recommended to detect impairment of autonomic reflexes. Treatment should always follow a stepwise approach with initial use of nonpharmacologic interventions including avoidance of hypotensive medications, high-salt diet and physical counter maneuvers. If these measures are not sufficient, medications such as fludrocortisone and midodrine can be added. The goals of treatment are to improve symptoms and to make the patient as ambulatory as possible instead of targeting arbitrary blood pressure values.

Management approaches to hypertension in autonomic failure

PURPOSE OF REVIEW

Supine hypertension is a common finding in autonomic failure that can worsen orthostatic hypotension and predispose to end-organ damage. This review focuses on nonpharmacologic and pharmacologic approaches to manage hypertension in these patients in the face of disabling orthostatic hypotension.

RECENT FINDINGS

The hypertension of autonomic failure can be driven by sympathetic-dependent or independent mechanisms, contingent on the site of autonomic lesions. Management of supine hypertension should include simple nonpharmacologic approaches including avoiding the supine position during the daytime and sleeping in a head-up tilt position at night. Most patients, however, require pharmacologic treatment. Several antihypertensive therapies lower nighttime pressure in autonomic failure, but none improve nocturnal volume depletion or morning orthostatic tolerance. Regardless, treatment may still be beneficial in some patients but must be decided on an individual basis. Blood pressure monitoring is helpful in this regard, as well as titration of doses, as these patients are hypersensitive to depressor agents due to loss of baroreceptor reflexes.

SUMMARY

Autonomic failure provides a unique opportunity to study blood pressure regulation independent of autonomic influences. Understanding mechanisms driving supine hypertension will have important implications for the treatment of autonomic failure and will improve our knowledge of cardiovascular regulation in other populations, including essential hypertension and elderly hypertensive individuals with comorbid orthostatic hypotension.

Angiotensin II, independent of plasma renin activity, contributes to the hypertension of autonomic failure

At least half of primary autonomic failure patients exhibit supine hypertension, despite profound impairments in sympathetic activity. Although the mechanisms underlying this hypertension are unknown, plasma renin activity is often undetectable, suggesting renin-angiotensin (Ang) pathways are not involved. However, because aldosterone levels are preserved, we tested the hypothesis that Ang II is intact and contributes to the hypertension of autonomic failure. Indeed, circulating Ang II was paradoxically increased in hypertensive autonomic failure patients (52±5 pg/mL, n=11) compared with matched healthy controls (27±4 pg/mL, n=10; P=0.002), despite similarly low renin activity (0.19±0.06 versus 0.34±0.13 ng/mL per hour, respectively; P=0.449). To determine the contribution of Ang II to supine hypertension in these patients, we administered the AT(1) receptor blocker losartan (50 mg) at bedtime in a randomized, double-blind, placebo-controlled study (n=11). Losartan maximally reduced systolic blood pressure by 32±11 mm Hg at 6 hours after administration (P<0.05), decreased nocturnal urinary sodium excretion (P=0.0461), and did not worsen morning orthostatic tolerance. In contrast, there was no effect of captopril on supine blood pressure in a subset of these patients. These findings suggest that Ang II formation in autonomic failure is independent of plasma renin activity, and perhaps Ang-converting enzyme. Furthermore, these studies suggest that elevations in Ang II contribute to the hypertension of autonomic failure, and provide rationale for the use of AT(1) receptor blockers for treatment of these patients.

Arterial hypertension, a tricky side of Parkinson's disease: physiopathology and therapeutic features

The role of arterial hypertension (HT) as risk factor for Parkinson's disease (PD) is still debated. Case-control and retrospective studies do not support an association between HT and PD and the risk of PD seems to be lower in hypertensive than in normotensive subjects. In addition, the use of calcium-channel blockers (CCBs) and angiotensin-converting enzyme inhibitors seems to have a protective effect on the risk of developing PD. In clinical practice, a crucial finding in subjects with PD is the high supine systolic blood pressure (SBP) coupled with orthostatic hypotension (OH). It is not clear whether this SBP load could be a risk factor for target organ damage as this load can be largely due to the drugs used to treat OH (i.e., fludrocortisone acetate, midodrine) or PD itself (i.e., monoamine oxidase inhibitors, dopamine D2-receptor antagonists). This blood pressure (BP) load is largely independent of medications as the 40 % of subjects with PD have a non-dipping pattern of BP during 24 h ambulatory monitoring (24-h ABPM). In PD, nocturnal HT is usually asymptomatic and 24-h ABPM should be used to track both supine HT and OH. Treatment of HT in PD is difficult because the reduction of supine BP could worsen OH. To avoid this, short-acting dihydropyridine CCBs, clonidine or nitrates are recommended, assuming between meals, in late afternoon or in the evening in avoiding an aggravation in the post-prandial hypotension characteristic of PD.

Neurocardiology: therapeutic implications for cardiovascular disease

The term "neurocardiology" refers to physiologic and pathophysiological interplays of the nervous and cardiovascular systems. This selective review provides an update about cardiovascular therapeutic implications of neurocardiology, with emphasis on disorders involving primary or secondary abnormalities of catecholamine systems. Concepts of scientific integrative medicine help understand these disorders. Scientific integrative medicine is not a treatment method or discipline but a way of thinking that applies systems concepts to acute and chronic disorders of regulation. Some of these concepts include stability by negative feedback regulation, multiple effectors, effector sharing, instability by positive feedback loops, allostasis, and allostatic load. Scientific integrative medicine builds on systems biology but is also distinct in several ways. A large variety of drugs and non-drug treatments are now available or under study for neurocardiologic disorders in which catecholamine systems are hyperfunctional or hypofunctional. The future of therapeutics in neurocardiology is not so much in new curative drugs as in applying scientific integrative medical ideas that take into account concurrent chronic degenerative disorders and interactions of multiple drug and non-drug treatments with each other and with those disorders.

Mechanisms of orthostatic hypotension and supine hypertension in Parkinson disease

Non-motor aspects of Parkinson disease (PD) are now recognized to be important both clinically and scientifically. Among these facets are abnormalities in blood pressure regulation. As much as 40% of PD patients have orthostatic hypotension (OH), which is usually associated with supine hypertension (SH). Symptoms of OH range from light-headedness to falls with serious trauma. SH, while typically asymptomatic, poses a significant increased risk for cardiovascular morbidity and mortality. Neuroimaging, neurochemical, and neuropharmacological studies indicate cardiac and extra-cardiac sympathetic noradrenergic denervation and baroreflex failure in virtually all PD patients with OH, and cardiac sympathetic denervation has been confirmed histopathologically. Mechanisms of SH in PD+OH remain poorly understood. The diurnal blood pressure profile shows increased variability that is correlated with decreased baroreflex gain and with increased morbidity and mortality. Treatment should be individually tailored according to the timing of OH or SH, using primarily short-acting sympathomimetic medications in the daytime for OH and short-acting antihypertensive in the nighttime for SH. Future research is needed to understand better and attenuate blood pressure fluctuations through manipulations that improve baroreflex function.

Autonomic dysfunction in older people

The autonomic nervous system comprises the sympathetic, parasympathetic and enteric nervous systems and plays an integral role in homeostasis. This includes cardiovascular and temperature control, glucose metabolism, gastrointestinal and reproductive function and increasing evidence to support its involvement in the inflammatory response to infection and cancer. Ageing is associated with autonomic dysfunction, and many clinical syndromes associated with older adults are due to inadequate autonomic responses to physiological stressors. The aim of this review is to explore the relationship between autonomic dysfunction and ageing illustrated with examples of maladaptive autonomic responses in a variety of different clinical syndromes including an exploration of autonomic cellular changes. Appropriate investigation and management strategies are outlined, recognizing the fine balance needed to improve symptoms without creating further medical complications.

Clinostatic hypertension and orthostatic hypotension

BACKGROUND

The association of clinostatic hypertension (CH) and orthostatic hypotension (OH) is described as the "Hyp-Hyp phenomenon," and it has been found in about 5.5% of hypertensive patients and in up to 50% of patients with OH. The importance of CH/OH in clinical practice is mainly due to the presence of troublesome symptoms, end-organ damage, and difficulties in its clinical management.

HYPOTHESIS

The review focuses on the clinical problem of CH and review the international literature for the best management, including the diagnostic work-up and the taylored treatment for this kind of patients.

METHODS

A systematic review of the literature was conducted through MEDLINE research to focus the main controversial issues about CH/OH. Included topics: (1) the diagnostic work-up, (2) the association with dysautonomic failure and syncope, and (3) the treatment options and prevention of end-organ damage.

RESULTS

Current standard reference for OH diagnosis includes functional assessment of the cardiac vagal nervous system and the sympathetic adrenergic system. The association with dysautonomic failure and with syncope needs further investigation. Pharmacologic treatment of OH is aimed at controlling symptoms rather than restoring normotension. Midodrine is the only medication that has been put to multicenter placebo-controlled trial and subsequently approved by the U.S. Food and Drug Administration (FDA) for OH treatment. Short-acting oral antihypertensive agents at bedtime should be considered in patients with severe, sustained CH.

CONCLUSIONS

Data obtained from the literature review showed that clinical diagnosis of the Hyp-Hyp phenomenon is relatively simple, but it remains more difficult to establish the causal disease. In our opinion, it is advisable to define simple diagnostic standards for the selection of patients at risk of dysautonomic impairment so that a subsequent highly specific diagnostic work-up could be initiated.

Ventilatory and cardiovascular responses to hypercapnia and hypoxia in multiple-system atrophy

BACKGROUND

Loss of medullary sympathoexcitatory neurons may contribute to baroreflex failure, leading to orthostatic hypotension in multiple-system atrophy (MSA). The cardiovascular responses to chemoreflex activation in MSA have not been explored to date.

OBJECTIVES

To determine whether ventilatory and cardiovascular responses to hypercapnia and hypoxia during wakefulness are systematically impaired in MSA.

DESIGN

Case-control study.

SETTING

Mayo Clinic, Rochester, Minnesota.

PATIENTS

Sixteen patients with probable MSA (cases) and 14 age-matched control subjects (controls).

MAIN OUTCOME MEASURES

Minute ventilation, blood pressure, and heart rate responses to hypercapnia and hypoxia during wakefulness. Hypercapnia was induced by a rebreathing technique and was limited to a maximal expiratory partial pressure of carbon dioxide of 65 mm Hg. Hypoxia was induced by a stepwise increase in inspiratory partial pressure of nitrogen and was limited to a minimal arterial oxygen saturation of 80%. Ventilatory responses were assessed as slopes of the regression line relating minute ventilation to changes in arterial oxygen saturation and partial pressure of carbon dioxide.

RESULTS

In cases, ventilatory responses to hypercapnia and hypoxia were preserved, despite the presence of severe autonomic failure, while cardiovascular responses to these stimuli were impaired. Among cases, hypercapnia elicited a less robust increase in arterial pressure than among controls, and hypoxia elicited a depressor response rather than the normal pressor responses (P < .001 for both).

CONCLUSIONS

Ventilatory responses to hypercapnia and hypoxia during wakefulness may be preserved in patients with MSA, despite the presence of autonomic failure and impaired cardiovascular responses to these stimuli. A critical number of chemosensitive medullary neurons may need to be lost before development of impaired automatic ventilation during wakefulness in MSA, whereas earlier loss of medullary sympathoexcitatory neurons may contribute to the impaired cardiovascular responses in these patients.

Severe transient hypertension after greater palatine foramen block in a patient taking midodrine

We report an episode of transient, severe hypertension occurring within 2 minutes of injection of 1% lidocaine with 1:100,000 U of epinephrine in a patient taking midodrine for orthostatic hypotension. We hypothesize that the patient's autonomic nervous system was dangerously susceptible to the effect of local anesthetic when combined with the vasoactive systemic effect of midodrine. Surgeons should minimize the use of vasoconstrictors in patients treated with midodrine to avoid hypertensive complications.

Renal impairment of pure autonomic failure

Supine hypertension is difficult to manage in patients with pure autonomic failure (PAF), because treatment can worsen orthostatic hypotension. Supine hypertension in PAF has been associated with left ventricular hypertrophy, but end organ damage in the kidney has not been assessed. We reviewed hemodynamic and laboratory data of 64 male patients with PAF who were 69+/-11 (mean+/-SD) years old. Systolic blood pressure fell by 67+/-40 mm Hg within 10 minutes of standing, with an inappropriately low 13+/-11-bpm increase in heart rate. Plasma norepinephrine levels were below normal (0.62+/-0.32 nmol/L supine and 1.28+/-1.25 nmol/L standing). A control data set of 75 men (67+/-12 years) was obtained from a deidentified version of the Vanderbilt University Medical Center electronic medical chart database. Compared with controls, PAF patients had lower hemoglobin (8.3+/-0.9 versus 9.3+/-0.8 mmol/L; P<0.001), packed cell volume (0.40+/-0.04 versus 0.45+/-0.04; P<0.001), and red blood cell count (4.4+/-0.5 x 10(12) versus 5.0+/-0.5 x 10(12) cells/L; P<0.001). Serum creatinine and blood urea nitrogen levels were elevated in patients. Forty-eight percent of patients with PAF had supine hypertension (supine systolic blood pressure: > or = 150 mm Hg). Serum creatinine was higher in patients with supine hypertension (133+/-44 versus 106+/-27 micromol/L; P=0.021) and estimated glomerular filtration rate was lower (57+/-22 versus 70+/-20 mL/min per 1.73 m2; P=0.022) compared with patients who did not have supine hypertension. These findings may indicate that renal function is diminished in PAF in association with supine hypertension.

Hypertension increases cerebral 6-18F-fluorodopa-derived radioactivity

6-(18)F-fluorodopa PET depicts the striatal dopaminergic lesion characterizing Parkinson disease (PD); however, striatal uptake of 6-(18)F-fluorodopa-derived radioactivity can be normal. Supine hypertension (SH) might increase 6-(18)F-fluorodopa uptake.

METHODS

We measured putamen, caudate, and occipital cortex 6-(18)F-fluorodopa-derived radioactivity and supine blood pressure in patients with PD + SH (systolic pressure >/= 180 mm Hg, n = 8), patients with PD without SH (PD - SH, n = 19), patients with pure autonomic failure (n = 8), and controls (n = 16).

RESULTS

Peak putamen radioactivity correlated with supine systolic pressure across all subjects and among PD patients and was higher in PD + SH than in PD - SH (P = 0.01). Both subgroups had rapid fractional declines in radioactivity between the peak and late values (P < 0.0001, compared with controls). Arterial 6-(18)F-fluorodopa concentrations were similar in the compared groups.

CONCLUSION

In PD, SH is associated with augmented striatal 6-(18)F-fluorodopa-derived radioactivity. Regardless of SH, retention of 6-(18)F-fluorodopa-derived radioactivity is markedly reduced. A model-independent approach can identify striatal dopaminergic denervation in PD.

Interferon-alpha-2b/ribavirin-induced vestibulocochlear toxicity with dysautonomia in a chronic hepatitis C patient

A 57-year-old man developed vertigo, tinnitus, bilateral hearing loss and postural intolerance temporally related to the administration of pegylated interferon-alpha-2b/ribavirin for chronic hepatitis C viral infection. Clinical examination showed bilateral sensorineural hearing loss, subjective vertigo with saccadic intrusions during fixation and smooth visual pursuit, and supine hypertension followed by orthostatic hypotension with inadequate reflexive compensatory cardiovascular responses. Laboratory assessment showed marked hemolytic anemia. Formal audiometry revealed high-frequency sensorineural hearing loss with abnormal high-frequency distortion product otoacoustic emissions, indicative of damage to the cochlear outer hair cells. Cessation of therapy resulted in rapid clinical resolution with mild residual hearing loss and tinnitus. This case report illustrates vestibulocochlear and autonomic nervous system adverse effects of pegylated interferon-alpha-2b/ribavirin, emphasizing the importance of early recognition and cessation of therapy to prevent permanent neurootologic injury.

Increased superoxide levels in ganglia and sympathoexcitation are involved in sarafotoxin 6c-induced hypertension

Endothelin (ET) type B receptors (ET(B)R) are expressed in multiple tissues and perform different functions depending on their location. ET(B)R mediate endothelium-dependent vasodilation, clearance of circulating ET, and diuretic effects; all of these should produce a fall in arterial blood pressure. However, we recently showed that chronic activation of ET(B)R in rats with the selective agonist sarafotoxin 6c (S6c) causes sustained hypertension. We have proposed that one mechanism of this effect is constriction of capacitance vessels. The current study was performed to determine whether S6c hypertension is caused by increased generation of reactive oxygen species (ROS) and/or activation of the sympathetic nervous system. The model used was continuous 5-day infusion of S6c into male Sprague-Dawley rats. No changes in superoxide anion levels in arteries and veins were found in hypertensive S6c-treated rats. However, superoxide levels were increased in sympathetic ganglia from S6c-treated rats. In addition, superoxide levels in ganglia increased progressively the longer the animals received S6c. Treatment with the antioxidant tempol impaired S6c-induced hypertension and decreased superoxide levels in ganglia. Acute ganglion blockade lowered blood pressure more in S6c-treated rats than in vehicle-treated rats. Although plasma norepinephrine levels were not increased in S6c hypertension, surgical ablation of the celiac ganglion plexus, which provides most of the sympathetic innervation to the splanchnic organs, significantly attenuated hypertension development. The results suggest that S6c-induced hypertension is partially mediated by sympathoexcitation to the splanchnic organs driven by increased oxidative stress in prevertebral sympathetic ganglia.

Orthostatic hypotension: framework of the syndrome

According to the 1996 consensus definition, orthostatic hypotension (OH) is diagnosed when a fall in systolic blood pressure of at least 20 mm Hg and/or diastolic blood pressure of at least 10 mm Hg within 3 min of standing is recorded. The elements of orthostatic blood pressure drop that are relevant to the definition of OH include magnitude of the drop, time to reach the blood pressure difference defined as OH, and reproducibility of the orthostatic blood pressure drop. In each of these elements, there exist issues that argue for modification of the presently accepted criteria of OH. Additional questions need to be addressed. Should one standard orthostatic test be applied to different patient populations or should tests be tailored to the patients' clinical circumstances? Are different OH thresholds relevant to various clinical settings, aetiologies of OH and comorbidity? Which test has the best predictive power of morbidity and mortality?