Cardiac autonomic regulation following a 246-km mountain ultra-marathon: An observational study.

Physical exercise requires integrated autonomic and cardiovascular adjustments to maintain homeostasis. We aimed to observe acute posture-related changes in blood pressure, and apply a portable noninvasive monitor to measure the heart index for detecting arrhythmia among elite participants of a 246-km mountain ultra-marathon. Nine experienced ultra-marathoners (8 males and 1 female) participating in the Run Across Taiwan Ultra-marathon in 2018 were enrolled. The runners' Heart Spectrum Blood Pressure Monitor measurements were obtained in the standing and supine positions before and immediately after the race. Their high-sensitivity troponin T and N-terminal proB-type natriuretic peptide levels were analyzed 1 week before and immediately after the event. Heart rate was differed significantly in the immediate postrace assessment compared to the prerace assessment, in both the standing (P = .011; d = 1.19) and supine positions (P = .008; d = 1.35). Postural hypotension occurred in 4 (44.4%) individuals immediately postrace. In 3 out of 9 (33.3%) recruited finishers, the occurrence of premature ventricular complex signals in the standing position was detected; premature ventricular complex signal effect was observed in the supine position postrace in only 1 participant (11.1%). Premature ventricular complex signal was positively correlated with running speed (P = .037). Of the 6 individuals who completed the biochemical tests postrace, 2 (33.3%) had high-sensitivity troponin T and 6 (100%) had N-terminal proB-type natriuretic peptide values above the reference interval. A statistically significant increase was observed in both the high-sensitivity troponin T (P = .028; d = 1.97), and N-terminal proB-type natriuretic peptide (P = .028; d = 2.91) levels postrace compared to prerace. In conclusion, significant alterations in blood pressure and heart rate were observed in the standing position, and postexercise (postural) hypotension occurred among ultra-marathoners. The incidence of premature ventricular complexes was higher after the race than before.

Orthostatic Hypotension and Antihypertensive Treatment in Lung Transplant Recipients: A Cross-Sectional Study.

OBJECTIVES: Lung transplant is the ultimate treatment of many end-stage lung diseases. Calcineurin inhibitors, crucial in immunosuppression for lung transplant recipients, are linked to secondary hypertension, necessitating antihypertensive treatment. In addition, lung transplant recipients frequently experience orthostatic hypotension, occasionally stemming from autonomic dysfunction, but also commonly attributed as a negative side effect of antihypertensive treatment. Our study aimed to evaluate the frequency of orthostatic blood pressure irregularities and investigate the involvement of antihypertensive treatment as a potential risk factor in the occurrence among lung transplant recipients. MATERIALS AND METHODS: Fifty-six consecutive lung transplant recipients, both inpatient and outpatient, at the University Hospital Zurich (Switzerland) were monitored from 1999 to 2013. Transplant recipients underwent a Schellong test (an active standing test). Our evaluation encompassed their initial traits, such as the existence of supine hypertension. We computed the odds ratio for the comparison of the likelihood of experiencing orthostatic hypotension while using a minimum of 1 type of antihypertensive medication versus absence of antihypertensive drugs. RESULTS: Of the lung transplant recipients, 25% showed a positive Schellong test. Within this group, 64% had supine hypertension, and 29% displayed symptoms of orthostatic hypotension. Among the patients, 71% were using at least 1 type of antihypertensive medication. The odds ratio for showing orthostatic hypotension while taking at least 1 type of antihypertensive drug versus the absence of antihypertensive medications was 1.64 (95% exact CI, 0.39-6.90) with P = .50. This finding remained consistent regardless of age, sex, inpatient or outpatient status, and the duration since transplant. CONCLUSIONS: Orthostatic blood pressure dysregulation is prevalent among lung transplant recipients, frequently without noticeable symptoms. In our cohort, the use of antihypertensive medications did not elevate the risk of orthostatic hypotension.

Blood Pressure Variability and Plasma Biomarkers of Neuronal Injury and Alzheimer's Disease: A Clinic-Based Study of Patients with Diseases Along the Heart-Brain Axis.

 Higher blood pressure variability (BPV) predisposes to cognitive decline. To investigate underlying mechanisms, we measured 24-h ambulatory BPV, nocturnal dipping and orthostatic hypotension in 518 participants with vascular cognitive impairment, carotid occlusive disease, heart failure, or reference participants. We determined cross-sectional associations between BPV indices and plasma biomarkers of neuronal injury (neurofilament light chain) and Alzheimer's disease (phosphorylated-tau-181 and Aß42/Aß40). None of the BPV indices were significantly associated with any of the biomarkers. Hence, in patients with diseases along the heart-brain axis, we found no evidence for an association between BPV and selected markers of neuronal injury or Alzheimer's disease.

Norepinephrine Reuptake Inhibition, an Emergent Treatment for Neurogenic Orthostatic Hypotension.

The NET (norepinephrine transporter) is situated in the prejunctional plasma membrane of noradrenergic neurons. It is responsible for >90% of the norepinephrine uptake that is released in the autonomic neuroeffector junction. Inhibitors of this cell membrane transporter, known as norepinephrine reuptake inhibitors (NRIs), are commercially available for the treatment of depression and attention deficit hyperactivity disorder. These agents increase norepinephrine levels, potentiating its action in preganglionic and postganglionic adrenergic neurons, the latter through activation of α-1 adrenoreceptors. Previous studies found that patients with neurogenic orthostatic hypotension can improve standing blood pressure and reduce symptoms of neurogenic orthostatic hypotension after a single administration of the selective NRI atomoxetine. This effect was primarily observed in patients with impaired central autonomic pathways with otherwise normal postganglionic sympathetic fibers, known as multiple system atrophy. Likewise, patients with normal or high norepinephrine levels may benefit from NRIs. The long-term efficacy of NRIs for the treatment of neurogenic orthostatic hypotension-related symptoms is currently under investigation. In summary, an in-depth understanding of the pathophysiology of neurogenic orthostatic hypotension resulted in the discovery of a new therapeutic pathway targeted by NRI.

Orthostatic hypotension, cognition and structural brain imaging in hemodynamically impaired patients.

BACKGROUND: Orthostatic hypotension (OH) is associated with an increased risk of dementia, potentially attributable to cerebral hypoperfusion. We investigated which patterns and characteristics of OH are related to cognition or to potentially underlying structural brain injury in hemodynamically impaired patients and healthy reference participants. METHODS: Participants with carotid occlusive disease or heart failure, and reference participants from the Heart-Brain Connection Study underwent OH measurements, neuropsychological assessment and brain MRI. We analyzed the association between OH, global cognitive functioning, white matter hyperintensity (WMH) volume and brain parenchymal fraction with linear regression. We stratified by participant group, severity and duration of OH, chronotropic incompetence and presence of orthostatic symptoms. RESULTS: Of 337 participants (mean age 67.3 ± 8.8 years, 118 (35.0%) women), 113 (33.5%) had OH. Overall, presence of OH was not associated with cognitive functioning (ß: -0.12 [-0.24-0.00]), but we did observe worse cognitive functioning in those with severe OH (≥ 30/15 mmHg; ß: -0.18 [-0.34 to -0.02]) and clinically manifest OH (ß: -0.30 [-0.52 to -0.08]). These associations did not differ significantly by OH duration or chronotropic incompetence, and were similar between patient groups and reference participants. Similarly, both severe OH and clinically manifest OH were associated with a lower brain parenchymal fraction, and severe OH also with a somewhat higher WMH volume. CONCLUSIONS: Severe OH and clinically manifest OH are associated with worse cognitive functioning. This supports the notion that specific patterns and characteristics of OH determine its impact on brain health.

Treatment of Orthostatic Hypotension During Acute Inpatient Rehabilitation After Spinal Cord Injury: Usual Care vs. Anti-hypotensive Therapy.

BACKGROUND: To compare the pharmacological treatment of hypotension and orthostatic hypotension (OH) initiated based upon a blood pressure (BP) threshold, regardless of symptoms (TXT), to usual care pharmacological treatment of symptomatic hypotension (UC), during acute inpatient rehabilitation (AIR) following spinal cord injury (SCI). METHODS: Block randomization, based on the neurological level of injury as: cervical lesions (C1-C8); high thoracic lesions (T1-T5), and low thoracic lesions (T6-T12), was used to determine responses to the primary question "was the therapy session affected by low BP or concern for low BP development?" Study participants and therapists were unaware of the group assignment. RESULTS: A total of 66 participants enrolled; 25 (38%) in the TXT group, 29 (44%) in the UC group, and 12 (18%) withdrew. Responses to the primary question were recorded for 32 participants, 15 in the TXT, and 17 in the UC group. There was an average of 81 ±â€…51 therapy sessions/participant in the TXT and 60 ±â€…27 sessions/participant in the UC group. Of those therapy sessions, low BP or concerns for low BP affected an average of 9 ±â€…8 sessions/participant in the TXT group and 10 ±â€…12 sessions/participant in the UC group. Neither the total number of therapy sessions (P = 0.16) nor group assignment (P = 0.83) significantly predicted the number of sessions affected by low BP. CONCLUSIONS: These data are not conclusive but indicate that the treatment of asymptomatic hypotension and OH does not increase time spent in therapy compared to UC treatment of symptomatic hypotension and OH in newly injured patients with SCI. CLINICAL TRIALS REGISTRATION: #NCT02919917.

Longitudinal prevalence of neurogenic orthostatic hypotension in the idiopathic Parkinson Progression Marker Initiative (PPMI) cohort.

BACKGROUND: Reported orthostatic hypotension (OH) prevalence in Parkinson's disease (PD) varies widely, with few studies evaluating specifically neurogenic-OH (nOH). The ratio of orthostatic heart rate (HR) to systolic blood pressure (SBP) change (Δ) is a valid screening method to stratify nOH/non-nOH but has had minimal epidemiologic application. OBJECTIVE: To estimate the prevalence of nOH and non-nOH in the PPMI using the ΔHR/ΔSBP ratio and examine associations between nOH and various motor and non-motor measures. METHODS: Longitudinal orthostatic vitals and motor and non-motor measures were extracted (baseline-month 48). Patients were consensus criteria classified as OH+/-, with ΔHR/ΔSBP sub-classification to nOH (ΔHR/ΔSBP < 0.5) or non-nOH (ratio ≥ 0.5). Prevalence was determined across visits. Independent linear mixed models tested associations between nOH/non-nOH and clinical variables. RESULTS: Of N = 907 PD with baseline orthostatic vitals, 3.9 % and 1.8 % exhibited nOH and non-nOH, respectively. Prevalence of nOH/non-nOH increased yearly (P = 0.012, chi-square), though with modest magnitude (baseline: 5.6 % [95 % CI: 4.3-7.3 %]; month 48: 8.6 % [6.4-11.5 %]). nOH patients were older than PD with no OH and nOH was associated with greater impairment of motor and independent functioning than non-nOH/OH- groups. Cognitive function and typical OH symptoms were worse in PD + OH, generally. CONCLUSIONS: nOH prevalence was greater than non-nOH in the PPMI early PD cohort, with modest prevalence increase over time. Our findings are consistent with prior studies of large cohorts that evaluated nOH, specifically. Those with early PD and nOH were likelier to be older and suffer from greater motor and functional impairment, but OH presence was generally associated with more cognitive impairment.

Exploring Cardiovascular Autonomic Function before and after Chronic Deep Brain Stimulation in Parkinson's Disease.

BACKGROUND: Blood pressure control in Parkinson's disease (PD) under subthalamic deep brain stimulation (STN-DBS) is influenced by several intertwined aspects, including autonomic failure and levodopa treatment. OBJECTIVE: To evaluate the effect of chronic STN-DBS, levodopa, and their combination on cardiovascular autonomic functions in PD. METHODS: We performed cardiovascular reflex tests (CRTs) before and 6-months after STN-DBS surgery in 20 PD patients (pre-DBS vs. post-DBS). CRTs were executed without and with medication (med-OFF vs. med-ON). RESULTS: CRT results and occurrence of neurogenic orthostatic hypotension (OH) did not differ between pre- and post-DBS studies in med-OFF condition. After levodopa intake, the BP decrease during HUTT was significantly greater compared to med-OFF, both at pre-DBS and post-DBS evaluation. Levodopa-induced OH was documented in 25% and 5% of patients in pre-DBS/med-ON and post-DBS/med-ON study. CONCLUSION: Chronic stimulation did not influence cardiovascular responses, while levodopa exerts a relevant hypotensive effect. The proportion of patients presenting levodopa-induced OH decreases after STN-DBS surgery.

Orthostatic hypotension in Parkinson's disease: Sit-to-stand vs. supine-to-stand protocol and clinical correlates.

BACKGROUND: Screening for orthostatic hypotension (OH) is integral in Parkinson's disease (PD) management, yet evidence-based guidelines on best practice methods for diagnosing OH in PD are lacking. METHODS: We investigated the frequency and correlates of OH, symptomatic OH, and neurogenic OH, in a large consecutively recruited PD cohort (n = 318), and compared the diagnostic performance of the sit-to-stand vs. the supine-to-stand blood pressure (BP) test. We evaluated the utility of continuous BP monitoring and tilt table testing in patients with postural symptoms or falls who were undetected to have OH with clinic-based BP measurements. Disease severity, fluid intake, orthostatic and overactive bladder symptoms, falls, comorbidities and medication history were evaluated. RESULTS: Patients' mean age was 66.1 ± 9.5years, with mean disease duration 7.8 ± 5.5years. OH frequency was 35.8 % based on the supine-to-stand test. OH in PD was significantly associated with older age, lower body mass index, longer disease duration, worse motor, cognitive and overactive bladder symptoms and functional disabilities, falls, and lower fluid intake. A similar profile was seen with asymptomatic OH. Three quarters of OH were neurogenic, with the majority also having supine hypertension. The sit-to-stand test had a sensitivity of only 0.39. One quarter of patients were additionally diagnosed with OH during continuous BP monitoring. CONCLUSIONS: The sit-to-stand test substantially underdiagnoses OH in PD, with the important practice implication that supine-to-stand measurements may be preferred. Screening for OH is warranted even in asymptomatic patients. Adequate fluid intake, treatment of urinary dysfunction and falls prevention are important strategies in managing PD patients with OH.

A novel mechanism of idiopathic orthostatic hypotension and hypocatecholaminemia due to autoimmunity against aromatic l-Amino acid decarboxylase.

Orthostatic hypotension (OH) is a common condition. Many potential etiologies of OH have been identified, but in clinical practice the underlying cause of OH is often unknown. In the present study, we identified a novel and extraordinary etiology of OH. We describe a first case of acquired severe OH with syncope, and the female patient had extremely low levels of catecholamines and serotonin in plasma, urine and cerebrospinal fluid (CSF). Her clinical and biochemical evidence showed a deficiency of the enzyme aromatic l-amino acid decarboxylase (AADC), which converts l-DOPA to dopamine, and 5-hydroxytryptophan to serotonin, respectively. The consequence of pharmacologic stimulation of catecholaminergic nerves and radionuclide examination revealed her catecholaminergic nerves denervation. Moreover, we found that the patient's serum showed presence of autoantibodies against AADC, and that isolated peripheral blood mononuclear cells (PBMCs) from the patient showed cytokine-induced toxicity against AADC. These observations suggest that her autoimmunity against AADC is highly likely to cause toxicity to adrenal medulla and catecholaminergic nerves which contain AADC, resulting in hypocatecholaminemia and severe OH. Administration of vitamin B6, an essential cofactor of AADC, enhanced her residual AADC activity and drastically improved her symptoms. Our data thus provide a new insight into pathogenesis and pathophysiology of OH.

Hypotensive episodes at 24-h ambulatory blood pressure monitoring predict adverse outcomes in Parkinson's disease.

PURPOSE: Neurogenic orthostatic hypotension (nOH) is a frequent nonmotor feature of Parkinson's disease (PD), associated with adverse outcomes. Recently, 24-h ambulatory blood pressure monitoring (ABPM) showed good accuracy in diagnosing nOH. This study aims at evaluating the prognostic role of ABPM-hypotensive episodes in predicting PD disability milestones and mortality and comparing it to the well-defined prognostic role of bedside nOH. METHODS: Patients with PD who underwent ABPM from January 2012 to December 2014 were retrospectively enrolled and assessed for the development of falls, fractures, dementia, bed/wheelchair confinement, hospitalization, and mortality, during an up-to-10-year follow-up. Significant ABPM-hypotensive episodes were identified when greater than or equal to two episodes of systolic BP drop ≥ 15 mmHg (compared with the average 24 h) were recorded during the awakening-to-lunch period. RESULTS: A total of 99 patients (74% male, age 64.0 ± 10.1 years, and PD duration 6.4 ± 4.0 years) were enrolled. At baseline, 38.4% of patients had ABPM-hypotensive episodes and 46.5% had bedside nOH. On Kaplan-Meier analysis, patients with ABPM-hypotensive episodes showed earlier onset of falls (p = 0.001), fractures (p = 0.004), hospitalizations (p = 0.009), bed/wheelchair confinement (p = 0.032), dementia (p = 0.001), and shorter survival (8.0 versus 9.5 years; p = 0.009). At Cox regression analysis (adjusted for age, disease duration, Charlson Comorbidity Index, and Hoehn and Yahr stage) a significant association was confirmed between ABPM-hypotensive episodes and falls [odds ratio (OR) 3.626; p = 0.001), hospitalizations (OR 2.016; p = 0.038), and dementia (OR 2.926; p = 0.008), while bedside nOH was only associated with falls (OR 2.022; p = 0.039) and dementia (OR 1.908; p = 0.048). CONCLUSIONS: The presence of at least two ABPM-hypotensive episodes independently predicted the development of falls, dementia, and hospitalization, showing a stronger prognostic value than the simple bedside assessment.

Progressive QTc prolongation and reduced heart rate variability in dementia with Lewy bodies compared to Alzheimer's disease.

INTRODUCTION: Autonomic dysfunction (AuD) is a significant clinical challenge in patients with Dementia with Lewy Bodies (DLB). Manifestations of AuD such as orthostatic hypotension (OH) is associated with falls and decreased quality of life. Cardiac autonomic denervation is an early phenomenon in DLB and a potential contributor to OH. This retrospective study was undertaken to explore whether routine ECG tracings could be used to identify signs of autonomic dysfunction in DLB. METHODS: 18 patients with DLB and 18 age-matched patients with Alzheimer's disease (AD) were included. ECGs and clinical data were analyzed retrospectively for heart rate variability (HRV) and QTc interval prolongation. RESULTS: During an average of 10 years observation time (first to last ECG recording), the QTc interval increased in the DLB group, but not in the AD group. HRV was significantly lower at end of follow-up in the DLB group than in the AD group. DLB patients with OH had greater QTc prolongation. CONCLUSION: Longitudinal ECG analysis indicates that signs of AuD in DLB are reflected on routine ECG tracings. If confirmed in larger cohorts, this could influence risk stratification and help direct preventive measures.

Association Between Orthostatic Hypertension and Frailty Among Older Patients With Hypertension.

BACKGROUND: Frailty frequently coexists with hypertension in older patients. We aimed to evaluate the association between frailty and positional change in blood pressure, especially orthostatic hypertension. METHODS: Participants were recruited from 12 University hospitals in South Korea. Using a digital device, trained research nurses measured blood pressure in the supine and standing positions. Physical frailty was evaluated using the Korean version of the FRAIL questionnaire, gait speed, and handgrip strength. Orthostatic hypertension was defined as a ≥20-mm Hg increase in systolic blood pressure within 3 minutes of standing and upright systolic blood pressure of ≥140 mm Hg. RESULTS: We analyzed the data of 2065 participants who had been enrolled until December 31, 2022. The mean age was 73.2±5.6 years, and 52.0% were female. The mean blood pressure was 137.1±14.9/75.1±9.7 mm Hg. Among the participants, 1886 (91.3%) showed normal response after standing, but 94 (4.6%) had orthostatic hypertension, and 85 (4.1%) had orthostatic hypotension. Orthostatic hypertension was associated with female sex, obesity, cognitive function, physical frailty, and lower quality of life. In the multivariable analysis, body mass index and frailty status were independently associated with orthostatic hypertension. CONCLUSIONS: Orthostatic hypertension is associated with physical frailty, cognitive impairment, and low quality of life in older patients with hypertension. Therefore, evaluation of orthostatic blood pressure changes to confirm orthostatic hypertension or hypotension in frail older adults will serve as an important diagnostic procedure in vulnerable patients. Further studies are required to identify the underlying mechanisms of this association.

Impaired vestibular function associated with orthostatic hypotension in patients with multiple system atrophy.

BACKGROUND: Orthostatic hypotension (OH) is one of the most common symptoms in patients with multiple system atrophy (MSA). Vestibular system plays an important role in blood pressure regulation during orthostatic challenges through vestibular-sympathetic reflex. The current study aimed to investigate the relationship between vestibular function and OH in patients with MSA. METHODS: Participants with MSA, including 20 with OH (mean age, 57.55 ± 8.44 years; 7 females) and 15 without OH (mean age, 59.00 ± 8.12 years; 2 females) and 18 healthy controls (mean age, 59.03 ± 6.44 years; 8 females) were enrolled. Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) tests were conducted to evaluate vestibular function. RESULTS: Patients with MSA presented with significantly higher rate of absent cVEMPs (57.1% vs 11.1%, p = 0.001) and oVEMPs (25.7% vs 0, p = 0.021) than controls. MSA patients with OH showed more absent cVEMPs (75.0% vs 11.1%, Bonferroni corrected p < 0.001) and oVEMPs (40.0% vs 0, Bonferroni corrected p = 0.003) than controls. Patients with OH also showed higher rate of absent cVEMPs than those without OH (33.3%, Bonferroni corrected p = 0.014). CONCLUSIONS: Our results demonstrated that impairment of vestibular function was associated with MSA, particularly in those with OH. Absent VEMPs may be a potential marker for MSA severity. Our findings suggest that impaired vestibular function is involved in OH development and may serve as an intervention target.

Blood Pressure Response and Symptoms During Active Standing Test Among Hospitalized and Outpatients With Heart Failure: Results From the GRAVITY-HF Prospective Observational Cohort Study.

BACKGROUND: We conducted a multicenter, prospective, observational study to describe the incidence of orthostatic hypotension (OH) and orthostatic hypertension (OHtn) and its association with symptoms at standing and outcomes in patients with heart failure (HF). METHODS AND RESULTS: 321 active standing tests were performed in 87 inpatients during admission, and 316 tests were performed in 208 outpatients during follow-up. Blood pressure (BP) was measured by an automatic device 4 times in the supine position and at 1, 3 and 5 minutes of standing. Patients were queried about symptoms of orthostatic intolerance. The incidence of OH and OHtn was similar in both groups at baseline (classical OH 11%-22%, OHtn 3%-8%, depending on definition and timing). Reproducibility of BP changes with standing was low. Up to 50% of cases with abnormal responses were asymptomatic. Symptoms were variable and occurred mainly during the first minute of standing and had a U-shaped association with BP changes. OH in outpatients with HF was associated with a higher risks of death or readmission due to HF. CONCLUSIONS: Patients with HF have variable hemodynamic responses and symptoms during repeated active standing tests. OH might identify outpatients with HF who are at risk of long-term negative outcomes.

Synchronous Bilateral Brachial Blood Pressure Measurements Increased Orthostatic Hypotension Detection in the Elderly.

BACKGROUND: Orthostatic hypotension (OH) is a common clinical sign, but its detection rate is low, and it is difficult to repeat because there is no standardized screening method available. AIM: This study aimed to establish a method for detecting blood pressure and assess whether it could increase the OH detection rate in the elderly. METHODS: From May to October, 2022, 178 patients with symptomatic OH and 286 subjects with asymptomatic OH were selected. BP from the bilateral brachial artery was measured using two electronic sphygmomanometers on both arms at the same time, in the order of supine, sitting, and standing at 0-3 min. OH should meet 20/10 mmHg, standing BP minus sitting BP. The OH detection rates were calculated and compared. The symptomatic OH group was more often older, slimmer, had lower ADL scores, and contained fewer smokers (all P< 0.05). RESULTS: The detection rate of the symptomatic OH group using the modified method was 59.55%, which was higher than that of the routine method (34.83% vs. 59.55%, P<0.05). The detection rate using the modified method in the OH group with asymptomatic OH was 20.63%, which was higher than that of the routine method (20.63% vs. 5.59%, P< 0.01). CONCLUSION: Synchronous measurement of bilateral brachial artery BP in supine, sitting, and standing positions increased the detection rate of OH in the elderly.

Orthostatic variation of pulmonary artery pressure in ambulatory heart failure patients.

AIM: To study effect of change in position (supine and standing) on pulmonary artery pressure (PAP) in ambulatory heart failure (HF) patients. METHODS: Seventeen patients with CardioMEMS® sensor and stable heart failure were consented and included in this single center study. Supine and standing measurements were obtained with at least 5 min interval between the two positions. These measurements included PAP readings utilizing the manufacturer handheld interrogator obtaining 10 s data in addition to the systemic blood pressure and heart rate recordings. RESULTS: Mean supine and standing readings and their difference (Δ) were as follows respectively: Systolic PAP were 33.4 (± 11.19), 23.6 (± 10) and Δ was 9.9 mmHg (p = 0.0001), diastolic PAP were 14.2 (± 5.6), 7.9 (± 5.7) and Δ was 6.3 mmHg (p = 0.0001) and mean PAP were 21.8 (± 7.8), 14 (± 7.2) and Δ was 7.4 mmHg (p = 0.0001) while the systemic blood pressure did not vary significantly. CONCLUSION: There is orthostatic variation of PAP in ambulatory HF patients demonstrating a mean decline with standing in diastolic PAP by 6.3 mmHg, systolic PAP by 9.9 mmHg and mean PAP by 7.4 mmHg in absence of significant orthostatic variation in systemic blood pressure or heart rate. These findings have significant clinical implications and inform that PAP in each patient should always be measured in the same position. Since initial readings at the time of implant were taken in supine position, it may be best to use supine position or to obtain a baseline standing PAP reading if standing PAP is planned on being used.