The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P =0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P =0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01308099.

Introduction The Chiari network is an uncommon vestigial structure of the heart that is often clinically insignificant. We present an unusual case of infective endocarditis affecting only the Chiari network in a patient who presented with septic emboli to the lungs and brain. Case summary A 61-year-old man was admitted with a 2-month history of hemoptysis, pleuritic chest pain, and right upper extremity numbness and weakness. He was found to have multifocal bilateral pulmonary opacities and an abscess collection in the brain. Blood cultures grew Streptococcus intermedius and transthoracic echocardiogram (TTE) was normal. Subsequent transesophageal echocardiogram (TEE) revealed an 8.3 × 4.6 mm vegetation arising from the Chiari network, close to the right atrial appendage, without involvement of the tricuspid valve or any of the other valves. There were no atrial or ventricular septal defects. He was treated with appropriate antibiotics with improvement of symptoms. Repeat imaging showed improvement of the lung opacities, but not the brain abscess, warranting transfer to another hospital for neurosurgical intervention. Conclusion The diagnosis and management of isolated Chiari network endocarditis require a high index of clinical suspicion. A multidisciplinary approach incorporating both medical and surgical approaches where necessary is essential for optimal outcome.

BACKGROUND: Supine hypertension affects most patients with orthostatic hypotension (OH) due to autonomic failure, but it is often untreated for fear of worsening OH. We hypothesized that increasing intrathoracic pressure with continuous positive airway pressure (CPAP) had a Valsalva-like blood-pressure-lowering effect that could be used to treat nocturnal supine hypertension in these patients, while reducing nocturnal pressure diuresis and improving daytime OH. METHODS: In Protocol 1, we determined the acute hemodynamic effects of increasing levels of CPAP (0, 4, 8, 12, and 16 cm H 2 O, 3 minutes each) in 26 patients with autonomic failure and supine hypertension studied while awake and supine. In Protocol 2 (n=11), we compared the effects of overnight therapy with CPAP (8–12 cm H 2 O for 8 hours) versus placebo on nocturnal supine hypertension, nocturnal diuresis and daytime OH in a 2-night crossover study. RESULTS: In Protocol 1, acute CPAP (4–16 cm H 2 O) decreased systolic blood pressure in a dose-dependent manner (maximal drop 22±4 mmHg with CPAP 16) due to reductions in stroke volume (−16+3%) and cardiac output (−14±3%). Systemic vascular resistance and heart rate remained unchanged. In Protocol 2, overnight CPAP lowered nighttime systolic blood pressure (maximal change −23±5 versus placebo −1±7 mmHg; P =0.023) and was associated with lower nighttime diuresis (609±84 versus placebo 1004±160 mL; P =0.004) and improved morning orthostatic tolerance (AUC upright SBP 642±121 versus placebo 410±109 mmHg*min; P =0.014). CONCLUSIONS: CPAP is a novel nonpharmacologic approach to treat the supine hypertension of autonomic failure while improving nocturia and daytime OH. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03312556.

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