Advertisement

To define cardiovascular and heart rate variability (HRV) changes following head-up tilt (HUT) in children/adolescents with Chronic Fatigue Syndrome (CFS) in comparison to age- and gender-matched controls.

Twenty-six children/adolescents with CFS (11-19 years) and controls underwent 70-degree HUT for a maximum of 30 min, but returned to horizontal earlier at the participant's request with symptoms of orthostatic intolerance (OI) that included lightheadedness.

Using electrocardiography and beat-beat finger blood pressure, a positive tilt was defined as OI with 1) neurally mediated hypotension (NMH); bradycardia (HR <75% of baseline), and hypotension [systolic pressure (SysP) drops >25 mm Hg)] or 2) postural orthostatic tachycardia syndrome (POTS); HR increase >30 bpm, or HR >120 bpm (with/without hypotension).

• Thirteen CFS and five controls exhibited orthostatic intolerance generating a sensitivity and specificity for HUT of 50.0% and 80.8%, respectively.
• POTS without hypotension occurred in seven CFS subjects but no controls.
• POTS with hypotension and NMH occurred in both.
• Predominant sympathetic components to HRV on HUT were measured in CFS tilt-positive subjects.

In conclusion, CFS subjects were more susceptible to OI than controls, the cardiovascular response predominantly manifest as POTS without hypotension, a response unique to CFS suggesting further investigation is warranted with respect to the pathophysiologic mechanisms involved.

Source: Pediatric Research. Dec 10, 2007. [E-pub ahead of print] PMID: 18091356, by Galland BC, Jackson PM, Sayers RM, Taylor BJ. Department of Women’s & Children’s Health, University of Otago, Dunedin, New Zealand.