Symposium review: high altitude travel with pulmonary vascular disease.

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension are the main precapillary forms of pulmonary hypertension (PH) summarized as pulmonary vascular diseases (PVD). PVDs are characterized by exertional dyspnoea and oxygen desaturation, and reduced quality of life and survival. Medical therapies improve life expectancy and physical performance of PVD patients, of whom many wish to participate in professional work and recreational activities including traveling to high altitude. The exposure to the hypobaric hypoxic environment of mountain regions incurs the risk of high altitude adverse events (AEHA) due to severe hypoxaemia exacerbating symptoms and further increase in pulmonary artery pressure, which may lead to right heart decompensation. Recent prospective and randomized trials show that altitude-induced hypoxaemia, pulmonary haemodynamic changes and impairment of exercise performance in PVD patients are in the range found in healthy people. The vast majority of optimally treated stable PVD patients who do not require long-term oxygen therapy at low altitude can tolerate short-term exposure to moderate altitudes up to 2500 m. PVD patients that reveal persistent severe resting hypoxaemia ( S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$  <80% for >30 min) at 2500 m respond well to supplemental oxygen therapy. Although there are no accurate predictors for AEHA, PVD patients with unfavourable risk profiles at low altitude, such as higher WHO functional class, lower exercise capacity with more pronounced exercise-induced desaturation and more severely impaired haemodynamics, are at increased risk of AEHA. Therefore, doctors with experience in PVD and high-altitude medicine should counsel PVD patients before any high-altitude sojourn. This review aims to summarize recent literature and clinical recommendations about PVD patients travelling to high altitude.

The effect of high altitude (2500†m) on incremental cycling exercise in patients with pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension: a randomised controlled crossover trial.

BACKGROUND: Our objective was to investigate the effect of a day-long exposure to high altitude on peak exercise capacity and safety in stable patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). METHODS: In a randomised controlled crossover trial, stable patients with PAH or distal CTEPH without resting hypoxaemia at low altitude performed two incremental exercise tests to exhaustion: one after 3-5 h at high altitude (2500 m) and one at low altitude (470 m). RESULTS: In 27 patients with PAH/CTEPH (44% females, mean±sd age 62±14 years), maximal work rate was 110±64 W at 2500 m and 123±64 W at 470 m (-11%, 95% CI -16- -11%; p<0.001). Oxygen saturation measured by pulse oximetry and arterial oxygen tension at end-exercise were 83±6% versus 91±6% and 6.1±1.9 versus 8.6±1.9 kPa (-8% and -29%; both p<0.001) at 2500 versus 470 m, respectively. Maximal oxygen uptake was 17.8±7.5 L·min-1·kg-1 at high altitude versus 20±7.4 L·min-1·kg-1 at low altitude (-11%; p<0.001). At end-exercise, the ventilatory equivalent for carbon dioxide was 43±9 at 2500 m versus 39±9 at 470 m (9%, 95% CI 2-6%; p=0.002). No adverse events occurred during or after exercise. CONCLUSIONS: Among predominantly low-risk patients with stable PAH/CTEPH, cycling exercise during the first day at 2500 m was well tolerated, but peak exercise capacity, blood oxygenation and ventilatory efficiency were lower compared with 470 m.

Influence of dental prophylaxis procedures on the tooth veneer interface in resin-based composite and polymer-infiltrated ceramic veneer restorations: an in vitro study.

OBJECTIVES: The aim of this study was to investigate the influence of dental prophylaxis cleaning procedures and artificial aging on veneers in human teeth. The external marginal and internal tooth veneer as well as the restoration surfaces were examined. MATERIAL AND METHODS: Thirty-two extracted premolars were restored with resin-based composite (RBC) and polymer-infiltrated ceramic network (PICN) veneers. Artificial aging by alternating thermocycling and subsequent prophylaxis procedure (glycine-based powder air polishing or ultrasonic scaling) was conducted for five consecutive cycles. The external marginal interface was examined by height profile measurements and the internal interface was investigated using micro X-ray computed tomography. In addition, the surface texture of the veneer surface was analyzed using confocal laser scanning microscopy. RESULTS: The application of both prophylaxis procedures resulted in a deepening of the marginal interface (10 µm ± 8 µm) for materials. Furthermore, the internal interface of PICN restorations showed marginal gaps after both treatments and artificial aging (16 µm ± 3 µm). In contrast to the RBC specimens, a significant increase in surface roughness was identified for PICN veneers after ultrasonic scaling. CONCLUSIONS: The marginal and internal interface regions in veneers fabricated from PICN and RBC were affected by prophylaxis procedures. Furthermore, it may result in increased veneer surface roughness, especially in PICN and after ultrasonic scaling, which might affect bioadhesion and longevity. CLINICAL RELEVANCE: After dental prophylaxis procedures, examination of the marginal and the internal interface as well as the veneer surface provides a precise insight into damage mechanisms and offers an assessment of longevity.

[General measures and management of pulmonary arterial hypertension]. / Allgemeine Maßnahmen und Management der pulmonalarteriellen Hypertonie.

Care of patients with pulmonary arterial hypertension (PAH) needs a multi-facetet concept and measures, including management of adverse reactions, right heart insufficiency as well as information on pregnancy, travels by air, psychosocial support, physical exercise training and prophylaxis by vaccination.Positive study results led to an higher recommendation of specialized exercise training in pulmonary hypertension. Also, the recommendation on iron substitution was amended according to the current evidence.In the current guidelines, special focus was given to the elaboration of recommendations regarding pregnancy, including patient information, contraception and patient management in case of pregnancy.This article aims to provide an overview on the recommendations of general measuremes, special circumstances and patient management according to the ESC/ERS guidelines. Amendments to the guideline recommendations are given as comments from the authors of this article.

[Pulmonary Dyspnea]. / Pulmonale Dyspnoe.

INTRODUCTION: Dyspnea is one of the most common symptoms in patients with lung diseases. The term "dyspnea" refers to the subjective sensation of uncomfortable breathing, which is experienced and described very differently between individuals. Because of this, diagnosis can be very challenging and similar to pain, no true objective measurement parameters of dyspnea exist. A detailed symptom history and clinical examination are critical in establishing the diagnosis, but the severity of pulmonary functional impairment does not always correlate with the clinical picture. The diagnosis of lung diseases is led by pulmonary function tests and imaging techniques, which measure the response to therapy and assess the prognostic course of the disease. The purpose of this article is to review the causes of pulmonary dyspnea, present a guide to diagnostic work-up, and introduce common differential diagnoses.

BOPPY-based novel fluorescent dopamine D2 and D3 receptor ligands.

Dopamine is one of the crucial neurotransmitters in the human brain. Its out-of-range concentration can lead to various neurological diseases with special interest for dopamine D2 and D3 receptor subtypes. Although BODIPY is a highly versatile structural moiety for fluorescence labeling, we have looked out for structurally related pyridine-based moieties. We used BOPPY labelling of well-described D2R/D3R pharmacophores to obtain ligands with moderate to low nanomolar binding affinities as well as low to excellent quantum yields for bright fluorescence ligands. To best of our knowledge, this is the first report on the application of BOPPY fluorophores to GPCR ligands. This approach offers a general applicable way for fluorescence labelling via primary aliphatic amine elements.

Benzo[a]pyrene represses DNA repair through altered E2F1/E2F4 function marking an early event in DNA damage-induced cellular senescence.

Transcriptional regulation of DNA repair is of outmost importance for the restoration of DNA integrity upon genotoxic stress. Here we report that the potent environmental carcinogen benzo[a]pyrene (B[a]P) activates a cellular DNA damage response resulting in transcriptional repression of mismatch repair (MMR) genes (MSH2, MSH6, EXO1) and of RAD51, the central homologous recombination repair (HR) component, ultimately leading to downregulation of MMR and HR. B[a]P-induced gene repression is caused by abrogated E2F1 signalling. This occurs through proteasomal degradation of E2F1 in G2-arrested cells and downregulation of E2F1 mRNA expression in G1-arrested cells. Repression of E2F1-mediated transcription and silencing of repair genes is further mediated by the p21-dependent E2F4/DREAM complex. Notably, repression of DNA repair is also observed following exposure to the active B[a]P metabolite BPDE and upon ionizing radiation and occurs in response to a p53/p21-triggered, irreversible cell cycle arrest marking the onset of cellular senescence. Overall, our results suggest that repression of MMR and HR is an early event during genotoxic-stress induced senescence. We propose that persistent downregulation of DNA repair might play a role in the maintenance of the senescence phenotype, which is associated with an accumulation of unrepairable DNA lesions.

Cardiac function and pulmonary hypertension in Central Asian highlanders at 3250†m.

THE QUESTION ADDRESSED BY THE STUDY: Chronic exposure to hypoxia increases pulmonary artery pressure (PAP) in highlanders, but the criteria for diagnosis of high-altitude pulmonary hypertension (HAPH) are debated. We assessed cardiac function and PAP in highlanders at 3250 m and explored HAPH prevalence using different definitions. PATIENTS AND METHODS: Central Asian highlanders free of overt cardiorespiratory disease, permanently living at 2500-3500 m compared to age-matched lowlanders living <800 m. Participants underwent echocardiography close to their altitude of residence (at 3250 m versus 760 m). RESULTS: 173 participants (97 highlanders, 76 lowlanders), mean±sd age 49±9 years (49% females) completed the study. Results in lowlanders versus highlanders were systolic PAP (23±5 versus 30±10 mmHg), right ventricular fractional area change (42±6% versus 39±8%), tricuspid annular plane systolic excursion (2.1±0.3 versus 2.0±0.3 cm), right atrial volume index (20±6 versus 23±8 mL·m-2), left ventricular ejection fraction (62±4% versus 57±5%) and stroke volume (64±10 versus 57±11 mL); all between-group comparisons p<0.05. Depending on criteria, HAPH prevalence varied between 6% and 35%. THE ANSWER TO THE QUESTION: Chronic exposure to hypoxia in highlanders is associated with higher PAP and slight alterations in right and left heart function compared to lowlanders. The prevalence of HAPH in this large highlander cohort varies between 6% according to expert consensus definition of chronic high-altitude disease to 35% according to the most recent definition of pulmonary hypertension proposed for lowlanders.

Concatenating Suzuki Arylation and Buchwald-Hartwig Amination by A Sequentially Pd-Catalyzed One-Pot Process-Consecutive Three-Component Synthesis of C,N-Diarylated Heterocycles.

The concatenation of Suzuki coupling and Buchwald-Hartwig amination in a consecutive multicomponent reaction opens a concise, modular and efficient one-pot approach to diversely functionalized heterocycles, as exemplified for 3,10-diaryl 10H-phenothiazines, 3,9-diaryl 9H-carbazoles, and 1,5-diaryl 1H-indoles, in high yields starting from simple staring materials. Moreover, this one-pot reaction is a sequentially palladium-catalyzed process that does not require additional catalyst loading after the first coupling step.

Attention-Deficit Hyperactivity Disorder Symptom Status in a Mixed Gender Population of Opioid-Maintained Prison Inmates.

OBJECTIVE: Attention-deficit hyperactivity disorder (ADHD) often coincides with substance abuse and delinquency. A sample of opioid-maintained inmates was assessed for symptoms of ADHD, substance abuse history, types of offense, psychiatric comorbidities, and psychopharmacological treatment using a standardized battery of instruments. METHOD: Adult inmates (n = 133, mean age 35.7 years, 21.8% female) in opioid-maintenance therapy (OMT) were administered the Adult ADHD self-report scale, Wender Utah Rating Scale, Mini International Neuropsychiatric Interview, -European Addiction Severity Index. RESULTS: Fifty percent screened positive for childhood and 17% for adult ADHD, four (3.1%) received ADHD medication. Inmates with ADHD symptom status were significantly younger at first substance abuse, reported more drug overdoses, longer duration of cocaine and prescribed medication abuse and more in- and outpatient treatments (all p < 0.05). For all inmates in OMT a high rate of psychiatric comorbidities was observed (78.9%). CONCLUSION: There is a need for assessment of ADHD and other psychiatric comorbidities in OMT prisoners. Evidence-based treatment should be routinely provided.

Characteristics and risk profiles of patients with pulmonary arterial or chronic thromboembolic pulmonary hypertension living permanently at >2500 m of high altitude in Ecuador.

Over 80 Mio people worldwide live >2500 m, including at least as many patients with pulmonary vascular disease (PVD), defined as pulmonary arterial or chronic thromboembolic pulmonary hypertension (PAH/CTEPH), as elsewhere (estimated 0.1‰). Whether PVD patients living at high altitude have altered disease characteristics due to hypobaric hypoxia is unknown. In a cross-sectional study conducted at the Hospital Carlos Andrade Marin in Quito, Ecuador, located at 2840 m, we included 36 outpatients with PAH or CTEPH visiting the clinic from January 2022 to July 2023. We collected data on diagnostic right heart catheterization, treatment, and risk factors, including NYHA functional class (FC), 6-min walk distance (6MWD), and NT-brain natriuretic peptide (BNP) at baseline and at last follow-up. Thirty-six PVD patients (83% women, 32 PAH, 4 CTEPH, mean ± SD age 44 ± 13 years, living altitude 2831 ± 58 m) were included and had the following baseline values: PaO2 8.2 ± 1.6 kPa, PaCO2 3.9 ± 0.5 kPa, SaO2 91 ± 3%, mean pulmonary artery pressure 53 ± 16 mmHg, pulmonary vascular resistance 16 ± 4 WU, 50% FC II, 50% FC III, 6MWD 472 ± 118 m, BNP 490 ± 823 ng/L. Patients were treated for 1628 ± 1186 days with sildenafil (100%), bosentan (33%), calcium channel blockers (33%), diuretics (69%), and oxygen (nocturnal 53%, daytime 11%). Values at last visit were: FC (II 75%, III 25%), 6MWD of 496 ± 108 m, BNP of 576 ± 5774 ng/L. Compared to European PVD registries, ambulatory PVD patients living >2500 m revealed similar blood gases and relatively low and stable risk factor profiles despite severe hemodynamic compromise, suggesting that favorable outcomes are achievable for altitude residents with PVD. Future studies should focus on long-term outcomes in PVD patients dwelling >2500 m.

Clinical-radiological-pathological correlation in pulmonary hypertension with unclear and/or multifactorial mechanisms.

Ever since the second world symposium on pulmonary hypertension (PH) held in Evian, France, in 1998, PH has been classified into five major clinical groups. Group 5 PH includes a variety of distinct conditions with unclear and/or multifactorial underlying pathologies. Management of these patients is challenging as the number of patients within these groups is often small, not all individuals with certain underlying conditions are affected by PH and patients exhibit distinct symptoms due to different underlying diseases. Studies and clinical trials in these groups are largely lacking and mostly restricted to case series and registry reports. Nonetheless, the worldwide burden of group 5 PH is estimated to be significant in terms of the prevalence of some associated diseases. Group 5 PH encompasses six subgroups, including haematological disorders (inherited and acquired chronic haemolytic anaemia and chronic myeloproliferative disorders), systemic disorders (sarcoidosis, pulmonary Langerhans's cell histiocytosis and neurofibromatosis type 1), metabolic disorders (glycogen storage diseases and Gaucher disease), chronic renal failure with or without haemodialysis, pulmonary tumour thrombotic microangiopathy and fibrosing mediastinitis.

Influence of bariatric surgery on the peripheral blood immune system of female patients with morbid obesity revealed by high-dimensional mass cytometry.

Introduction: Obesity is associated with low-grade chronic inflammation, altered levels of adipocytokines, and impaired regulation of gastrointestinal hormones. Secreted, these factors exert immunostimulatory functions directly influencing peripheral immune cells. Methods: In the realm of this study, we aimed to investigate the composition and activation status of peripheral blood immune cells in female patients with morbid obesity compared to lean controls using high-dimensional mass cytometry. Besides, we also assessed the influence of bariatric surgery with respect to its ability to reverse obesity-associated alterations within the first-year post-surgery. Results: Patients with morbid obesity showed typical signs of chronic inflammation characterized by increased levels of CRP and fibrinogen. Apart from that, metabolic alterations were characterized by increased levels of leptin and resistin as well as decreased levels of adiponectin and ghrelin compared to the healthy control population. All these however, except for ghrelin levels, rapidly normalized after surgery with regard to control levels. Furthermore, we found an increased population of monocytic CD14+, HLA-DR-, CD11b+, CXCR3+ cells in patients with morbid obesity and an overall reduction of the HLA-DR monocytic expression compared to the control population. Although CD14+, HLA-DR-, CD11b+, CXCR3+ decreased after surgery, HLA-DR expression did not recover within 9 - 11 months post-surgery. Moreover, compared to the control population, patients with morbid obesity showed a perturbed CD4+ T cell compartment, characterized by a strongly elevated CD127+ memory T cell subset and decreased naïve T cells, which was not recovered within 9 - 11 months post-surgery. Although NK cells showed an activated phenotype, they were numerically lower in patients with morbid obesity when compared to healthy controls. The NK cell population further decreased after surgery and did not recover quantitatively within the study period. Conclusions: Our results clearly demonstrate that the rapid adaptions in inflammatory parameters and adipocytokine levels that occur within the first year post-surgery do not translate to the peripheral immune cells. Apart from that, we described highly affected, distinct immune cell subsets, defined as CD127+ memory T cells and monocytic CD14+, HLA-DR, CD11b+, CXCR3+ cells, that might play a significant role in understanding and further decoding the etiopathogenesis of morbid obesity.

Effect of Acetazolamide on Postural Control in Patients with COPD Travelling to 3100 m Randomized Trial.

Patients with chronic obstructive pulmonary disease (COPD) may be susceptible to impairments in postural control (PC) when exposed to hypoxia at high altitude. This randomized, placebo-controlled, double-blind, parallel-design trial evaluated the effect of preventive acetazolamide treatment on PC in lowlanders with COPD traveling to 3100 m. 127 lowlanders (85 men, 42 women) with moderate to severe COPD, aged 57 ± 8 y, living below 800 m, were randomized to treatment with acetazolamide 375 mg/d starting 24 h before ascent from 760 m to 3100 m and during a 2-day sojourn in a clinic at 3100 m. PC was evaluated at both altitudes with a balance platform on which patients were standing during five tests of 30 s each. The primary outcome was the center of pressure path length (COPL). In the placebo group, COPL significantly increased from (mean ± SD) 28.8 ± 9.7 cm at 760 m to 30.0 ± 10.0 cm at 3100 m (p = 0.002). In the acetazolamide group, COPL at 760 m and 3100 m were similar with 27.6 ± 9.6 cm and 28.4 ± 9.7 cm (p = 0.069). The mean between-groups difference (acetazolamide-placebo) in altitude-induced change of COPL was -0.54 cm (95%CI -1.66 to 0.58, p = 0.289). Multivariable regression analysis confirmed an increase in COPL of 0.98 cm (0.39 to 1.58, p = 0.001) with ascent from 760 to 3100 m, but no significant effect of acetazolamide (0.66 cm, 95%CI -0.25 to 1.57, p = 0.156) when adjusting for several confounders. In lowlanders with moderate to severe COPD, an ascent to high altitude was associated with impaired postural control and this was not prevented by acetazolamide.

Pulmonary arterial wedge pressure increase during exercise in patients diagnosed with pulmonary arterial or chronic thromboembolic pulmonary hypertension.

Background: The course of pulmonary arterial wedge pressure (PAWP) during exercise in patients with pulmonary arterial or chronic thromboembolic pulmonary hypertension (PAH/CTEPH), further abbreviated as pulmonary vascular disease (PVD), is still unknown. The aim of the study was to describe PAWP during exercise in patients with PVD. Methods: In this cross-sectional study, right heart catheter (RHC) data including PAWP, recorded during semi-supine, stepwise cycle exercise in patients with PVD, were analysed retrospectively. We investigated PAWP changes during exercise until end-exercise. Results: In 121 patients (59 female, 66 CTEPH, 55 PAH, 62±17 years) resting PAWP was 10.2±4.1 mmHg. Corresponding peak changes in PAWP during exercise were +2.9 mmHg (95% CI 2.1-3.7 mmHg, p<0.001). Patients ≥50 years had a significantly higher increase in PAWP during exercise compared with those <50 years (p<0.001). The PAWP/cardiac output (CO) slopes were 3.9 WU for all patients, and 1.6 WU for patients <50 years and 4.5 WU for those ≥50 years. Conclusion: In patients with PVD, PAWP increased slightly but significantly with the onset of exercise compared to resting values. The increase in PAWP during exercise was age-dependent, with patients ≥50 years showing a rapid PAWP increase even with minimal exercise. PAWP/CO slopes >2 WU are common in patients with PVD aged ≥50 years without exceeding the PAWP of 25 mmHg during exercise.

Effect of altitude and acetazolamide on sleep and nocturnal breathing in healthy lowlanders 40 y of age or older. Data from a randomized trial.

STUDY OBJECTIVES: To assess altitude-induced sleep and nocturnal breathing disturbances in healthy lowlanders 40 y of age or older and the effects of preventive acetazolamide treatment. METHODS: Clinical examinations and polysomnography were performed at 760 m and in the first night after ascent to 3100 m in a subsample of participants of a larger trial evaluating altitude illness. Participants were randomized 1:1 to treatment with acetazolamide (375 mg/day) or placebo, starting 24 h before and while staying at 3100 m. The main outcomes were indices of sleep structure, oxygenation, and apnea/hypopnea index (AHI). RESULTS: Per protocol analysis included 86 participants (mean ± SE 53 ± 7 y old, 66% female). In 43 individuals randomized to placebo, mean nocturnal pulse oximetry (SpO2) was 94.0 ± 0.4% at 760 m and 86.7 ± 0.4% at 3100 m, with mean change (95%CI) -7.3% (-8.0 to -6.5); oxygen desaturation index (ODI) was 5.0 ± 2.3 at 760 m and 29.2 ± 2.3 at 3100 m, change 24.2/h (18.8 to 24.5); AHI was 11.3 ± 2.4/h at 760 m and 23.5 ± 2.4/h at 3100 m, change 12.2/h (7.3 to 17.0). In 43 individuals randomized to acetazolamide, altitude-induced changes were mitigated. Mean differences (Δ, 95%CI) in altitude-induced changes were: ΔSpO2 2.3% (1.3 to 3.4), ΔODI -15.0/h (-22.6 to -7.4), ΔAHI -11.4/h (-18.3 to -4.6). Total sleep time, sleep efficiency, and N3-sleep fraction decreased with an ascent to 3100 m under placebo by 40 min (17 to 60), 5% (2 to 8), and 6% (2 to 11), respectively. Acetazolamide did not significantly change these outcomes. CONCLUSIONS: During a night at 3100 m, healthy lowlanders aged 40 y or older revealed hypoxemia, sleep apnea, and disturbed sleep. Preventive acetazolamide treatment improved oxygenation and nocturnal breathing but had no effect on sleep duration and structure. TRIAL REGISTRATION: The trial is registered at Clinical Trials, https://clinicaltrials.gov, NCT03561675.

Effect of acetazolamide on pulmonary vascular haemodynamics in patients with COPD going to altitude: a randomised, placebo-controlled, double-blind trial.

Background: COPD may predispose to symptomatic pulmonary hypertension at high altitude. We investigated haemodynamic changes in lowlanders with COPD ascending to 3100 m and evaluated whether preventive acetazolamide treatment would attenuate the altitude-induced increase in pulmonary artery pressure (PAP). Methods: In this randomised, placebo-controlled, double-blind, parallel-group trial, patients with COPD Global Initiative for Chronic Obstructive Lung Disease grades 2-3 who were living <800 m and had peripheral oxygen saturation (S pO2 ) >92% and arterial carbon dioxide tension <6 kPa were randomised to receive either acetazolamide (125-250 mg·day-1) or placebo capsules, starting 24 h before ascent from 760 m and during a 2-day stay at 3100 m. Echocardiography, pulse oximetry and clinical assessments were performed at 760 m and after the first night at 3100 m. Primary outcome was PAP assessed by tricuspid regurgitation pressure gradient (TRPG). Results: 112 patients (68% men, mean±sd age 59±8 years, forced expiratory volume in 1 s (FEV1) 61±12% pred, S pO2 95±2%) were included. Mean±sd TRPG increased from 22±7 to 30±10 mmHg in 54 patients allocated to placebo and from 20±5 to 24±7 mmHg in 58 patients allocated to acetazolamide (both p<0.05) resulting in a mean (95% CI) treatment effect of -5 (-9 to -1) mmHg (p=0.015). In patients assigned to placebo at 760/3100 m, mean±sd S pO2 was 95±2%/88±3%; in the acetazolamide group, the respective values were 94±2%/90±3% (both p<0.05), resulting in a treatment effect of +2 (1 to 3)% (p=0.001). Conclusions: In lowlanders with COPD travelling to 3100 m, preventive acetazolamide treatment attenuated the altitude-induced rise in PAP and improved oxygenation.

Change in Right-to-Left Shunt Fraction in Patients with Chronic Thromboembolic Pulmonary Hypertension after Pulmonary Endarterectomy.

BACKGROUND: Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (CTEPH) with accessible lesions. Breathing pure oxygen (hyperoxia) during right heart catheterization (RHC) allows for the calculation of the right-to-left shunt fraction (Qs/Qt). In the absence of intracardiac shunt, Qs/Qt can be used as a marker of ventilation-perfusion mismatch in patients with CTEPH. This study involved investigating Qs/Qt after PEA and its relation to other disease-specific outcomes. STUDY DESIGN AND METHODS: This study is a retrospective study that focuses on patients with operable CTEPH who had Qs/Qt assessment during RHC before and 1 year after PEA. Additionally, 6 min walking distance (6MWD), WHO functional class (WHO-FC), and NT-proBNP were assessed to calculate a four-strata risk score. RESULTS: Overall, 16 patients (6 females) with a median age of 66 years (quartiles 55; 74) were included. After PEA, an improvement in mean pulmonary artery pressure (38 [32; 41] to 24 [18; 28] mmHg), pulmonary vascular resistance (5.7 [4.0; 6.8] to 2.5 [1.4; 3.8] WU), oxygen saturation (92 [88; 93]% to 94 [93; 95]%), WHO-FC, and risk score was observed (all p < 0.05). No improvement in median Qs/Qt could be detected (13.7 [10.0; 17.5]% to 13.0 [11.2; 15.6]%, p = 0.679). A total of 7 patients with improved Qs/Qt had a significant reduction in risk score compared to those without improved Qs/Qt. CONCLUSION: PEA did not alter Qs/Qt assessed after 1 year in operable CTEPH despite an improvement in hemodynamics and risk score, potentially indicating a persistent microvasculopathy. In patients whose shunt fraction improved with PEA, the reduced shunt was associated with an improvement in risk score.

Effects of Acute Hypoxia on Heart Rate Variability in Patients with Pulmonary Vascular Disease.

Pulmonary vascular diseases (PVDs), defined as arterial or chronic thromboembolic pulmonary hypertension, are associated with autonomic cardiovascular dysregulation. Resting heart rate variability (HRV) is commonly used to assess autonomic function. Hypoxia is associated with sympathetic overactivation and patients with PVD might be particularly vulnerable to hypoxia-induced autonomic dysregulation. In a randomised crossover trial, 17 stable patients with PVD (resting PaO2 ≥ 7.3 kPa) were exposed to ambient air (FiO2 = 21%) and normobaric hypoxia (FiO2 = 15%) in random order. Indices of resting HRV were derived from two nonoverlapping 5-10-min three-lead electrocardiography segments. We found a significant increase in all time- and frequency-domain HRV measures in response to normobaric hypoxia. There was a significant increase in root mean squared sum difference of RR intervals (RMSSD; 33.49 (27.14) vs. 20.76 (25.19) ms; p < 0.01) and RR50 count divided by the total number of all RR intervals (pRR50; 2.75 (7.81) vs. 2.24 (3.39) ms; p = 0.03) values in normobaric hypoxia compared to ambient air. Both high-frequency (HF; 431.40 (661.56) vs. 183.70 (251.25) ms2; p < 0.01) and low-frequency (LF; 558.60 (746.10) vs. 203.90 (425.63) ms2; p = 0.02) values were significantly higher in normobaric hypoxia compared to normoxia. These results suggest a parasympathetic dominance during acute exposure to normobaric hypoxia in PVD.