Driving research of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME / CFS),
Post Treatment Lyme Disease Syndrome (PTLDS), Fibromyalgia and Post COVID .

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Heart Preload Failure

STUDY AIM
This study aims to evaluate these different explanations of PLF in ME/CFS patients to determine which is active in many, if not all, ME/CFS patients.

Lead

INVESTIGATORS

  • Wenzhong Xiao, PhD
  • David Systrom, MD

UPDATES

AND POTENTIAL
Two forms of heart failure identified in ME/CFS patients: preload failure and poor oxygen extraction. Preload failure consistently shows a reduced max VO2 (~80%) (VO2 max: maximum amount of oxygen your body can utilize during exercise) along with a reduced right atrial pressure (RAP). The poor oxygen extraction patients routinely also show a reduced max VO2 (~80%) and unexpectedly high pO2 in the mixed venous blood (pav O2). The first form suggests an autonomic dysregulation and the second form may suggest either mitochondrial oxidation or peripheral shunting dysfunction.

STUDY HYPOTHESIS AND DESCRIPTION

Invasive Cardiopulmonary Exercise Testing (iCPET) on ME/CFS patients shows a characteristic pattern of “preload failure” (PLF) that could be associated with postural orthostatic tachycardia syndrome (POTS) and/or post-exertion malaise (PEM).

The PLF comes in 2 forms, a high flow and a low flow. The low flow form may be caused by a failure to reduce venous compliance with exercise or a pre-existing reduced overall blood volume. However, the latter is less likely because the PLF persists even when one liter of saline is given to increase the blood volume just prior to the iCPET study.  On the other hand, the high flow PLF may be caused by peripheral arterial-venous shunt effects or deficient oxygen delivery or utilization. A final explanation is that blood travels through the peripheral capillary system normally but cellular oxygen uptake and/or utilization by the mitochondria is deficient. 

OBJECTIVES

ME/CFS patients impaired with PLF, as diagnosed by a single iCPET or by sequential iCPET, will be further evaluated.  This evaluation will measure large vessel vascular capacitance and blood volume, additional diagnostic testing (i.e., screening for adrenal insufficiency, tilt-table testing, nerve conduction studies) and the presence of peripheral shunting and oxygen delivery. Therapeutic intervention (i.e., hydration, increased sodium intake, β-adrenergic receptor antagonists, fludrocortisone, pyridostigmine, and/or midodrine), compression stockings, and monitored exercise training will also be employed based upon individual patient findings. 

Read more at the Harvard site 

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