Research Studies:

Circulatory Measurements

Orthostatic Stress  Testing & instrumentation

Circulatory Autonomic Testing

Lay Review with glossary

Orthostatic Intolerance (OI)

Circulatory Findings in POTS


Orthostatic Hypotension










    Welcome to the CFS Circulatory Study website. Researchers at New York Medical College in Valhalla NY have received funding from the National Institutes of Health (NIH) to study whether circulatory problems explain the symptoms and signs of the chronic fatigue syndrome in teenagers..

    The Principal Investigator for this study is Julian M. Stewart  MD, PhD, Professor of Pediatrics and Research Professor of Physiology at  New York Medical College.

    What comprises the study population? 
    What are the hypothesis and importance of the study?
    What are the symptoms and findings in patients?
    What is the goal of the study?
    What your own doctor can do to help diagnose CFS.
    How do I know if I知 eligible to be in this study? 
    Who pays for the exams, testing, and travel? 
    How can I get a screening application for this study? 
    If I decide to participate what does the study entail?


    What comprises the study population? 

    We are seeking patients aged 13-19 years old patients with chronic fatigue syndrome (CFS) who may benefit from an investigation for abnormalities of blood pressure, heart rate and blood flow. Patients have symptoms of chronic orthostatic intolerance (the inability to remain upright without symptoms) including dizziness, fatigue, nausea, headache, pallor, and neurocognitive loss (difficulty thinking) which overlap with the case definition of CFS.


    What is the hypothesis and importance

    We are investigating the hypothesis that a specific form of circulatory dysfunction produces the symptoms of CFS in teenagers. Recent investigations indicate that many  teenagers with CFS have a specific form of chronic orthostatic intolerance (the inability to remain upright without symptoms) called the postural tachycardia syndrome (POTS) which impairs blood flow and heart rate, and sometimes causes a fall in blood pressure. Fainting is less common. Results from our laboratory and other laboratories suggest that low blood volume or a defect in the contraction of blood vessels (vasoconstriction) causing a blood to accumulate inappropriately accounts for symptoms and findings in POTS. Blood vessel abnormalities can be detected even when they are lying down but become more evident when upright. Defects may vary from patient to patient and changes in limb color (e.g. purple discoloration) can occur when upright.


    What are the symptoms of POTS

     Fainting is uncommon. Symptoms of POTS and chronic orthostatic intolerance include dizziness, fatigue, nausea and abdominal pain, headache, pallor, and neurocognitive loss (difficulty thinking), shakiness and exercise intolerance overlap with the case definition of CFS.



    What is the goal of the study

    Our study will determine how often POTS occurs in CFS, and the mechanism(s) of POTS in individual patients. Specific causes for POTS may vary from patient to patient. Patients will be compared to healthy control subjects. We will also test a medication (proamatine) used for treating POTS which may help teenagers with CFS.



    What can your own doctor do

    Your doctor can rule out other illnesses such as infectious and inflammatory conditions which can produce similar symptoms. For example, most diagnostic blood tests should be performed by your own physician. This might include testing for thyroid disease, mycoplasma infection, Lyme disease, and Ebstein-Barr virus.  

    The tests we will be performing are not ordinarily available to your doctor. They are, however, all approved ways of measuring how blood vessels work. POTS can be treated by a combination of lifestyle adjustments and medication which your doctor can administer. The tests performed during the study may help us determine what treatment is best for you. We will provide you and your doctor with test results and treatment information.



    How do I know if I知 eligible to be in this study? 

    Even though the study focuses on CFS patients with circulatory dysfunction, all CFS patients are eligible to enroll. At this time we cannot predict who has circulatory dysfunction or if POTS is the only form of orthostatic intolerance in teenagers with CFS. Therefore all patients who fulfill the criteria for CFS (using the 1994 Centers for Disease Control definition) and are between 13 and 19 years old can enroll.

    The diagnosis of CFS should be made by a doctor, either your own physician or through contact with our center.

    Exclusion:The criteria for initial exclusion are adapted from the CDC and include: 1) an active medical condition that may explain the diagnosis; 2) a previous medical condition with undocumented resolution; 3) a past or current major psychiatric disorder; 4) a history of alcohol or substance abuse within 2 years before the onset of the chronic fatigue.

    Inclusion: The criteria for initial inclusion are adapted from the CDC:13 and 19 years old adolescents who have persistent or relapsing chronic fatigue of new or definite onset; and the concurrent occurrence of four or more of the following symptoms that have persisted or recurred during at least 6 consecutive months and have not predated the fatigue:
    1) impairment in memory or concentration severe enough to cause substantial reduction of previous levels of educational, social or personal activities. In adolescents this may be most notable by a decline in academic performance and school attendance;
    2) muscle pain or multi joint pain;
    3) headaches of a new type, pattern, or severity;
    4) unrefreshing sleep; and
    5) post-exertional malaise lasting more than 24

    Sore throat and swollen glands are unreliable criteria during adolescence .



    Who pays for the exams, or testing?

    There is no charge to you for any of the the testing or testing medication. We will pay each participant who $200 as a token of appreciation for their time.



    How can I get a screening application for this study? 

    You can click on the Screening icon, and download and print out the application and mail it to us. The mailing address is on the last page of the form. Alternatively you can email the application to stewart@nymc.edu or you can also fax us the application at 914-594-4513. Or, you can call us at 914-594-4370, leave your name and address on the voicemail and we値l mail you an application. 


    What happens if I知 eligible to be in the study and decide to participate? 

    If you would like to take part in this study, the study nurse will contact you to go over screening questionnaire material and discuss arranging for the study. The study nurse will review the consent form with you and we will also review the consent and any questions you may have when you arrive for the study. You and your parents should understand the study, and its risks and benefits. You can click on the icon for Consent Form to read the consent form for the study. It also provides additional information about the various procedures and tests used.

    We will make an appointment to come to The Center for Pediatric Hypotension for your study visit. You値l arrive at 9:00-10 AM on the day of your appointment. We ask that you not eat or drink anything after 8 AM that morning. Please wear comfortable clothing and bring along a pair of shorts and a short sleeve shirt. 

    We will meet you at the Bradhurst Building and take you to the laboratory area. Here the you will meet Dr. Jose Munoz and Dr. Julian Stewart who, along with the nurse, will review the study with you, and answer any questions you may have. After obtaining your or your parents' informed consent and informed assent if appropriate,  you値l answer a few questions, have a brief physical examination, and be taken to the laboratory area.

    Patients will undergo studies of blood flow while lying down and also when gradually tilted upright. We will assess arm and leg blood vessel properties. Simple tests of how the nervous system adjusts to changes in circulation will also be performed. We will also measure blood hormone levels and blood volume using a dye technique. There will be no invasive aspects to our tests except for the intravenous line to measure hormone levels and measure blood volume. 

    Over a 5 week period CFS patients will receive an FDA approved medication called proamatine (midodrine) which contracts blood vessels or a placebo (like a sugar pill) with no blood vessel properties for 2 weeks and then will have limited retesting. After a week to allow the drug to wear off, each patient will receive the other type of pill (placebo or drug) for 2 more weeks and be retested again. Neither patients nor investigators will know which order patients receive the pills until the study is over. We have already tested a similar intravenous drug called phenylephrine in a pilot group of patients which seems to benefit many patients without causing increased symptoms. 

    We believe that this study will help to determine the specific cause of POTS in CFS and will point towards improved medical therapy for teenage patients.

     We expect that your visit will take about 4 hours total with the laboratory part comprising 3 hours.

    If you have further questions about the study, please feel free to call:
    914-594-4370 for more information. 
    or Email at stewart@nymc.edu