Patient case (clinical description): A 23-year-old man comes to the emergency department following an episode of syncope.  He was working out when he felt dizzy and passed out without head injury.  He has had 3 other episodes of light-headedness over the last year, all happening during physical activity. He never had this experience while resting. He has no other medical conditions.  The patient does not use tobacco, alcohol, or illicit drugs.  His father died suddenly at age 35.  Vital signs are within normal limits.  On physical examination, the patient has a harsh systolic murmur.  The lungs are clear with no peripheral edema. Echocardiography shows asymmetric interventricular septal hypertrophy.

Patient's own account: I'm 23, and I got admitted to the ER because I fainted all of a sudden. I was in the gym, working out, when all of a sudden, I just got dizzy and passed out. Hopefully, I didn't hit my head. It's not my first time having that kind of dizziness at the gym, never when I'm chilling at home tho. I don't have any special medical conditions and I'm not even smoking, drinking or doing drugs! My dad died suddenly when he was 35, so I'm kind of scared. My vitals were normal while at the ER and they did a physical exam and they told me my heart sounds abnormal. My lungs are ok, but I had to do an echography of my heart, and they told me it is bigger than average.

Clinical trial: Mechanisms of Vasovagal Syncope

Eligibility criteria:
Inclusion Criteria:

          1. POTS patients referred for day to day orthostatic intolerance with greater than 3
             symptoms for greater than 3 months and will have the diagnosis of symptomatic postural
             tachycardia made during a screening tilt table test :

               -  dizziness

               -  nausea and vomiting

               -  palpitations

               -  fatigue

               -  headache

               -  exercise intolerance

               -  blurred vision

               -  abnormal sweating heat.

          2. Vasovagal Syncope patients will have at least 3 episodes of fainting episodes in the
             past year.

          3. Healthy control subjects

        Cases will be between the ages of 14 and 29 years old Cases will have normal physical
        examination, and normal electrocardiographic and echocardiographic evaluations.

        Only those free from heart disease, and from systemic illness will be eligible to
        participate.

        This excludes patients with illnesses and disease states known to be associated with
        endothelial cell dysfunction such as diabetes, renal disease, congestive heart failure,
        systemic hypertension, acute and chronic inflammatory diseases, neoplasm, immune mediated
        disease, trauma, morbid obesity and peripheral vascular disease.

        At the time of testing all patients and control subjects must refrain from vasoactive drugs
        for two weeks. Please check with us about any medication that you are taking.

        Exclusion Criteria:

          -  Cardiovascular causes of syncope

          -  An active medical condition that may explain the diagnosis

          -  A previous medical condition with undocumented resolution that may explain the
             diagnosis

          -  Past or present major psychiatric disorder

          -  Substance abuse within 2 years before onset of symptoms.
No condition on gender to be admitted to the trial.
Accepts Healthy Volunteers
Subject must be at least 14 Years old.
Subject must be at most 29 Years

Eligibility (NLI label): Contradiction