QT interval in children with orthostatic dysregulation: Changes in standing load.

BACKGROUND: The corrected QT interval (QTc) is affected by changes in autonomic sympathovagal modulation. The aim of this study was to determine whether children with orthostatic dysregulation (OD) have a longer QTc while standing than children without OD. METHODS: We retrospectively assessed patients who underwent the Schellong test and electrocardiography between November 2016 and November 2019. Patients who met the criteria of OD subtypes according to the Japanese clinical guidelines for juvenile OD (version 1) were classified as OD positive (the OD-positive group), and patients who did not meet the criteria were classified as OD negative (the OD-negative group). RESULTS: There were 73 patients in the OD-positive group and 52 patients in the OD-negative group. Baseline heart rate, QT interval, and QTc were comparable between the OD-positive and OD-negative groups. Heart rate after standing was significantly higher in the OD-positive group than in the OD-negative group (median: 33 bpm vs. 21 bpm, p < 0.001). Further, shortening of QT interval after standing was greater in the OD-positive group than in the OD-negative group (median: 19 ms vs. 8 ms, p = 0.015). The QTc significantly increased from baseline to standing in both groups. Changes in the QT interval corrected by Bazett's formula were greater in the OD-positive group than in the OD-negative group (median: 73 ms vs. 42 ms, p < 0.001). CONCLUSIONS: The QTc increased significantly from baseline to standing in the OD-positive group. Thus, a high QTc while standing could be considered an auxiliary marker for OD diagnosis.

The baroreceptor reflex brought to life outside the classroom - an e-learning based asynchronous laboratory class using a non-supervised modified Active Standing Test.

BACKGROUND: E-learning based laboratory classes can replace or enhance in-classroom laboratories. They typically offer temporal flexibility, self-determined learning speed, repeatability and do not require supervision or face-to-face contact. The aim of this feasibility study was to investigate whether the established in-classroom laboratory class on the baroreceptor reflex (BRR) can be transformed into a new e-learning based asynchronous laboratory class for untrained, non-supervised students without medical equipment. The BRR is a fundamental cardiovascular process which is regularly visualized in physiology during in-classroom laboratories by a student-performed Active Standing Test (AST). During this voluntary provocation of orthostatic stress, the BRR reliably causes a solid rise in heart rate (HR) and a stabilization or even increase in blood pressure (BP). METHODS: The conventional AST was modified by omission of BP measurements which would require medical devices and was embedded into a framework of interactive digital material allowing independent student performance. With specific adaptions, this instrument was implemented to 1st and 2nd year curricula of human medicine, dental medicine, midwifery and pharmacy. An audience response system was used to collect the students' data on HR, epidemiology, technical problems, satisfaction and orthostatic symptoms. As primary outcome, we investigated the students' correct performance of the modified AST regarding textbook conformity of the HR data. Secondary outcomes included technical feasibility, the students' satisfaction and consistency of HR data within predefined subgroups (e.g., gender, curricula). Descriptive statistics are reported. RESULTS: The class was completed by 217 students (mean age: 23 ± 8 [SD], 81% female, 19% male). Mean reported rise of HR during standing was ~ 20 bpm (~ 30%) which is highly concordant to textbooks. Reported feasibility (~ 80% negated any technical issues) and students' satisfaction (4.4 on 5-point Likert-scale) were high. The HR data were consistent within the subgroups. CONCLUSION: This study demonstrates that the highly relevant BRR can be successfully addressed in an e-learning based asynchronous laboratory class implementing a non-supervised AST restricted to HR measurements embedded in digital material. The robust HR response and the adjustable complexity allow an application to different healthcare-related curricula. This class, therefore, provides a broad audience access to a fundamental concept of cardiovascular physiology.

Pyridostigmine bromide versus fludrocortisone in the treatment of orthostatic hypotension in Parkinson's disease - a randomized controlled trial.

BACKGROUND AND PURPOSE: Evidence for effective treatment options for orthostatic hypotension (OH) in Parkinson's disease (PD) is scarce. Elevation of cholinergic tone with pyridostigmine bromide has been reported as a way to improve blood pressure (bp) regulation in neurogenic hypotension without causing supine hypertension. METHODS: This was a double-centre, double-blind, randomized, active-control, crossover, phase II non-inferiority trial of pyridostigmine bromide for OH in PD (clinicaltrials.gov NCT01993680). Patients with confirmed OH were randomized to 14 days 3 × 60 mg/day pyridostigmine bromide or 1 × 0.2 mg/day fludrocortisone before crossover. Outcome was measured by peripheral and central bp monitoring during the Schellong manoeuvre and questionnaires. RESULTS: Thirteen participants were enrolled between April 2013 and April 2015 with nine participants completing each trial arm. Repeated measures comparison showed a significant 37% improvement with fludrocortisone for the primary outcome diastolic bp drop on orthostatic challenge (baseline 22.9 ± 13.6 vs. pyridostigmine bromide 22.1 ± 17.0 vs. fludrocortisone 14.0 ± 12.6 mmHg; P = 0.04), whilst pyridostigmine bromide had no effect. Fludrocortisone caused an 11% peripheral systolic supine bp rise (baseline 128.4 ± 12.8 vs. pyridostigmine bromide 130.4 ± 18.3 vs. fludrocortisone 143.2 ± 10.1 mmHg; P = 0.01) but no central mean arterial supine bp rise (baseline 107.2 ± 7.8 vs. pyridostigmine bromide 97.0 ± 12.0 vs. fludrocortisone 107.3 ± 6.3 mmHg; P = 0.047). Subjective OH severity, motor score and quality of life remained unchanged by both study interventions. CONCLUSIONS: Pyridostigmine bromide is inferior to fludrocortisone in the treatment of OH in PD. This trial provides first objective evidence of the efficacy of 0.2 mg/day fludrocortisone for OH in PD, causing minor peripheral but no central supine hypertension. In addition to peripheral bp, future trials should include central bp measurements, known to correlate more closely with cardiovascular risk.