Preload failure

Preload failure or PLF occurs when the maximal exercise-induced cardiac output (CO) is decreased without an accompanying increase in right heart or pulmonary vascular pressures.

In cardiac physiology, preload is the end diastolic volume that stretches the right or left ventricle of the heart to its greatest dimensions under variable physiologic demand. It is defined as the length of the heart muscle just before it starts to pump and is measured clinically by the volume of blood in the left ventricle, the main pumping chamber, when it is most relaxed.

Preload can be influenced by blood volume, heart rhythm, left ventricular relaxation, and alterations in afterload.

ME/CFS

Preload failure is associated with exercise intolerance in myalgic encephalomyelitis/chronic fatigue syndrome, orthostatic hypotension, and postural orthostatic tachycardia.

Treatments

David Systrom at Brigham Women's Hospital in Boston is currently conducting phase III trials of Mestinon in patients with preload failure. Pyridostigmine (the generic name for Mestinon) has been investigated previously.

Notable studies and publications

• Pyridostigmine for Exercise Intolerance Treatment in Preload Failure - Meeting abstract)

See also

• Pyridostigmine
• Mestinon
• Invasive cardiopulmonary exercise test (iCPET)
• Post-exertional malaise
• Exercise intolerance

Learn more

• 2018, Advancements in ME/CFS Research, David M. Systrom, MD; Brigham and Women's Hospital | ME/CFSAlert 98 (Interview)

physiological Concerning living organisms, such as cells or the human body.  Physio logical (as in physio) is not to be confused with psych ological (emotional stress).

See myalgic encephalomyelitis.

See chronic fatigue syndrome.

phase three Last phase of clinical trials before a drug can be approved for public use. Whereas Phase one assesses basic safety, and Phase two assesses basic efficacy, Phase three uses many trial participants to fully assess both safety and efficacy, and overall benefit/risk.