are the symptoms and findings in patients
We are recruiting
patients with frequent fainting that is not due to heart disease or due
to conditions that cause nerve damage. We are also recruiting certain
patients with postural tachycardia . These are expected to be found
among patients that we encounter for research-related investigation of
The key feature of
postural VVS is loss of consciousness while upright, that is of rapid
onset, brief, and spontaneously terminating. In all cases, loss of
consciousness and postural tone occurs (i.e. the patient falls down) and
this is ultimately due to a critical reduction in brain blood flow. Most
patients have low blood pressure as the cause of reduced brain blood
flow. While syncope may occur due to heart disease at all ages the most
common variant is postural VVS in the young.
The key features
of POTS is symptoms which are
most prominent when standing. However, in some, findings are present
supine (lying down) but worsened standing. Symptoms of
POTS include dizziness in all patients, exercise provoked symptoms and
thus exercise intolerance, excessive fatigue, nausea and abdominal pain, headache,
shortness of breath and deep breathing, weakness, shakiness and postural
anxiety, pallor, and neurocognitive loss
(difficulty thinking). These occur on a day-to-day basis. The symptoms
with the case definition of chronic fatigue syndrome (CFS) and POTS is
often found in CFS in the young. Fainting is relatively uncommon during
is the goal of the study
study will determine whether blood flow regulation abnormalities
and abnormalities of sympathetic regulation are produced by nitric oxide
and can account for splanchnic pooling in VVS and POTS. Patients will be compared to healthy control
subjects. There is a detailed dietary questionnaire because diet may
contribute importantly to endogenous NO. There are several autonomic
There is no treatment arm although we can easily determine dietary or
medication interventions based on nitric oxide, nitrite and nitrate
excess if that is determined. If we know the specific biochemical mechanism we may be able
to offer further specific treatments to specific patients.
Significance: Results will determine whether abnormal NO and Ang-II
responses, and abnormal sympathetic stress responses are present early
in the course of obesity
indicating a need for intervention long before the more pernicious
effects of metabolic syndrome
can your own doctor do
We will ask for
the active participation of your doctor who can
rule out other illnesses that may complicate obesity. We will ask your
permission and for you doctor's permission to see an adolescent
medical doctor, Dr Kelly Bethea, who is participating in this study. In
particular, Dr. Bethea will perform physical examinations and
tests for metabolic syndrome which are essential to the study.
Many of the tests we will be
performing are not ordinarily available to your doctor. They are,
however, all approved ways of measuring how blood vessels and nerves work. The tests performed during the study
may help us determine whether any specific treatment is useful for you. We will provide
you and your doctor with test results and treatment information.
do I know if I知 eligible to be in this study?
3 or more episodes of VVS or severe presyncope within the past 12
months. Or neuropathic POTS.
Criteria for initial
exclusion will include a condition known to be associated with
autonomic, adrenergic, endothelial dysfunction or sympathetic nervous system abnormalities.
Additional exclusion will be for any active medical condition , a previous medical condition with undocumented resolution, past or present
disorder. 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, 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.
pays for the exams, or testing?
There is no
charge to you for any of the the testing directly related to this
study. We will
pay each participant $150 per day for their time.
can I get a questionnaire for this study?
You can click on
the Questionnaire 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
also fax us the application at 914-593-8890. Or, you can call us at
914-593-8888, leave your name and address on the voicemail and we値l
mail you an application.
happens if I知 eligible to be in the study and decide to participate?
If you would like
to take part in these studies, our research nurse coordinator, Courtney
Terilli will contact you to go over
questionnaire material and discuss arranging for any prior testing that
may be needed. We will also arrange for certain lab
testing during your time here for research purposes. Courtney 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 (if applicable) should understand the study, and its risks and
benefits. You can click on the icon for Consent Form to read about our
most of a week and you will also be asked to have a measurement of blood
volume. We will make
appointments to come to our center for your visits. You値l arrive at
9:30 AM on the day of your
appointment. We ask that you not eat or drink anything after 6 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
you will meet our nurse coordinator Courtney Terilli, and Drs. Julian Stewart
and Marvin Medow who, along with other staff, will review the study with you, and answer any questions you may
have. After obtaining informed consent you値l fill out several
questionnaires, have a
brief physical examination, give a urine sample, and be taken to the laboratory area.
We will meet you
at the Bradhurst Building and take you to the laboratory area. Here then
you will meet Dr. Julian Stewart and Dr. Marvin Medow who, along with the
Courtney will review the study with you, and answer any questions you may
have. After obtaining your or your parents informed consent you値l
receive several questionnaires concerning diet, syncope, autonomic
illness, and be taken to the laboratory area.
You will undergo
tests of how the nerves and blood vessels function.
measure blood flow properties of the leg and arm vein using noninvasive
techniques while lying flat. We will examine local
regulation of nitric oxide and norepinephrine made by adrenergic nerves
in your skin using a technique called
microdialysis and we will examine sympathetic nerve function using
In the first set
of experiments we use Laser-Doppler flowmetry (LDF) to measure skin blood flow while lying flat. This uses a
small beam of reflected light which you cannot feel. LDF will be
combined with microdialysis in which we put tiny tubes called
microdialysis probes within the skin of the leg using a small needle.
There will be four probes placed. This will enable us to measure how much
nitric oxide and norepinephrine you make and also your response to
gentle warming and to tiny amounts of norepinephrine itself. We
also will administer
small amounts of chemicals into the skin, testing the ability of the
blood vessels to react normally. The method only affects the tiny
area of skin tested and has no effect on overall circulation. Thus, we
can test how blood vessels work without disturbing the natural workings
of the heart and circulation. We will first stimulate local blood flow in two
ways: One uses gentle local heating over a small area of skin and the
other uses a medication called adenosine.
The tests will take place on two separate days. Each day last 4 hours or
On the other two
days we will
examine the specific dependence of the sympathetic nerves that use
norepinephrine (NE) to contract your blood vessels. These are
sympathetic adrenergic nerves. We will challenge your ability to release
NE in response to a moderate orthostatic challenge using a
well-established technique called lower body negative pressure while
measuring NO and NE. We will also record how well your nerves contract
to a drug, phenylephrine (neosynephrine) which stimulates the
sympathetic contraction response of blood vessels. These studies are
repeated when we reduce and when we increase nitric oxide using
medications. Sympathetic nerve activity is measured in a leg nerve
using a tiny electrode. There is no upright tilt involved.
that the lab visit will take about 6 hours.
If you have
further questions about the study, please feel free to call:
or Email at email@example.com