Long COVID Atlas › Glossary › Preload failure
MechanismPreload failure
https://longcovidatlas.org/glossary/preload-failure
In plain language
What it is
Not enough blood returning to fill the heart between beats, so a healthy pump is simply underfed during effort.
Why it matters
It is one specific reason exertion fails in long COVID, and it points toward different management than a muscle-level problem.
Think of it like
A good pump running half-dry because not enough water is reaching the tank.
For specialists
Formal definition
Reduced ventricular filling (low preload) on exertion, identified on invasive cardiopulmonary exercise testing and distinguished from a peripheral oxygen-extraction limit.
Mechanism
Impaired venous return, often linked to autonomic dysfunction and low blood volume, lowers cardiac filling during exercise; it has been documented alongside small-fiber neuropathy in post-COVID patients.
Sources
- Persistent exertional intolerance after COVID-19: insights from invasive cardiopulmonary exercise testing (Chest 2022) free full text ›