EEG Characteristics in Youth POTS and/or Syncope
Condition: Syncope; Postural Tachycardia Syndrome; Orthostatic Intolerance
MeSH terms: Syncope; Postural Orthostatic Tachycardia Syndrome; Orthostatic Intolerance; Tachycardia; Syndrome
Study type: Observational

Summary: 
      Orthostatic intolerance refers to symptoms that occur with standing and improve or resolve
      with recumbency. Few studies have evaluated orthostatic intolerance symptoms by
      electroencephalography (EEG), and none of those studies have focused on the adolescent-aged
      patient. This study will compare EEG characteristics and sweat rate during head-upright tilt
      (HUT) testing among patients with postural tachycardia syndrome (POTS) and patients with
      syncope without POTS. Patients with POTS will also undergo a separate HUT with abdominal and
      lower extremity compression. The primary aim of this study is to characterize video EEG
      changes that correspond with orthostatic intolerance in youth during HUT testing. The
      investigators hypothesize that the clinical encephalopathy related to POTS and referred to as
      'brain fog' will have an electrographic correlate. Secondary aims include (1) EEG comparisons
      of POTS symptoms with and without abdominal and lower extremity compression during HUT, (2)
      correlation between sweat rate and EEG changes during HUT, and (3) analysis of EEG
      characteristics that distinguish syncope with POTS from syncope without POTS. The
      investigators hypothesize that POTS patients have prolonged syncopal prodromes (compared to
      syncope patients without POTS) which are protective of syncope during daily activities.
    

Detailed description: 
      All POTS and syncope patients referred to Nationwide Children's Hospital (Columbus, OH) and
      meeting study eligibility criteria will be asked to participate. Consent and assent will be
      obtained per IRB guidelines. Consenting patients will undergo head-upright tilt (HUT) testing
      with video EEG and continuous sweat monitoring.

      Prior to testing all medicines that can affect orthostatic tolerance will be held a minimum
      of 5 half-lives. Caffeine will be held for a minimum of 24 hours. Urinalysis (for urine
      specific gravity) and pregnancy testing (for female patients of child-bearing age) will be
      done the day of HUT testing. A recumbent EEG sample of no less than 10 minutes will be
      obtained. EKG leads, Holter leads, blood pressure monitors (beat-to-beat and conventional arm
      cuff), intravenous (IV) line, and sweat monitors will be placed. Sweat rate, EEG, and blood
      pressure monitoring will be synchronized by event trigger, allowing co-registration of all
      timed studies during data post-processing. Serum norepinephrine levels will be obtained at
      the time of IV placement and at 10 minutes of tilt or during/immediately after the syncope
      prodrome if syncope occurs prior to 10 minutes.

      Once all monitors are placed, 10 minutes of EEG have been collected, and the patient has been
      recumbent for a minimum of 30 minutes, the table is tilted up-right to 70 degrees. A video
      camera will be on during the test. Patients are encouraged to report all symptoms and they
      are frequently examined for signs of pallor, acrocyanosis and sweating. Tilt testing is
      continued until syncope occurs, up to 10 minutes if the patient meets POTS criteria, or up to
      45 minutes if neither syncope or POTS is not present.

      Those who do meet age-appropriate POTS criteria (symptomatic heart-rate increment >40 bpm or
      symptomatic total HR of >130 bpm, all within 10 minutes of tilt for those <20 years of age)
      will be lowered at 10 minutes (or sooner with syncope) and asked to repeat testing with
      abdominal and lower extremity compression. The compression suit has been used by Dr. Heyer in
      other NCH studies. It is composed of a Neoprene-like material with 5 Velcro straps that fit
      snugly around the legs, thighs and abdomen. The abdominal strap contains an air-filled
      bladder that potentiates abdominal compression. We have used the suit in over 30 consenting
      patients from prior study. None of the study participants complained of discomfort. The suit
      successfully reduced both heart rate and orthostatic symptoms in youth with POTS; 55% of
      studied patients no longer met POTS diagnostic criteria while the suit was on (see PMID:
      24840763 for manuscript). We will use the compression suit as our method of attenuating POTS
      symptoms during HUT testing. EEG will be compared without and with compression.

      The time frame for this study is on average 90 minutes. It will not exceed 3 hours. After
      lowering the tilt table, all monitor leads and the IV will be removed. Once leads are removed
      there are no further study obligations.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients referred to the neurology-based POTS and Syncope clinic at Nationwide Children's
        Hospital (Columbus, OH) with POTS or with syncope without POTS and meeting eligibility
        criteria will be asked to participate.
      
Keywords: POTS; Syncope