Head-down tilt reduces the heart rate in postural tachycardia syndrome in acute setting: a pilot study 2023, Novak

Abstract
Background

Reduced preload and thoracic blood volume accompany postural tachycardia syndrome (POTS). Head-down tilt (HDT) increases both preload and intrathoracic blood volume. The objective of this study was to assess the safety and efficacy of HDT in POTS in acute settings.

Methods
This retrospective study evaluated POTS patients. Analyzed data included heart rate, blood pressure, cerebral blood flow velocity (CBFv) in the middle cerebral artery, and capnography. The baseline supine hemodynamic data were compared with the data obtained at the second minute of the −10° HDT. A linear mixed-effects model was used to assess the effect of HDT on hemodynamic variables.

Results
The HDT was explored in seven POTS patients and an additional seven POTS patients without HDT served as controls. In the HDT arm, four POTS patients had overlapping diagnoses of myalgic encephalopathy/chronic fatigue syndrome (ME/CFS) and one patient had comorbidity of post-acute sequelae of SARS-CoV-2 infection (PASC). HDT lowered heart rate by 10% and increased end-tidal CO2 by 8%. There was no change in other cardiovascular variables.

Conclusions
In the acute setting, HDT is safe. HDT reduces the heart rate presumably by modulating baroreflex by enhancing preload and stroke volume, which in turn increases thoracic blood volume with a net effect of parasympathetic cardiovagal activation and/or sympathetic withdrawal. This pilot study provides a foundation to proceed with longitudinal studies exploring the long-term effect of repetitive HDT in conditions associated with preload failure such as POTS, ME/CSF, and PASC.

https://link.springer.com/article/10.1007/s10072-023-07153-5

 

I suspect the HDT will be very unpopular in those with gastroesophageal reflux disease, heartburn, chronic indigestion and similar diseases.

And as someone who has Normal Pressure Hydrocephalus I have always hated being upside down or on a slope with my head below my feet. It increases the pressure in my head and after just a few seconds it hurts a lot.

 

I would really appreciate it if someone with access to the full article could let me know how long the patients were tilted for, and how long the reduction in tachycardia lasted afterwards, if that information is given in the study.