Hyperpnea in Postural Tachycardia


Up ] consent hyperpnea AHA.pdf ] Autonomic Questionnaire.pdf ]






    Welcome to the Hyperpnea in Postural Tachycardia Study website. Researchers at the Center for Hypotension at New York Medical College in Valhalla NY have received funding from the American Heart Association (AHA) to study the cause of increased breathing (hyperpnea) in  postural tachycardia syndrome in teenagers and young adults. Our most recent data indicate that this is particularly associated with sympathetic activation in important subsets of POTS.  

    The Principal Investigator is Dr. Julian Stewart

    What comprises the study population? 
    What is 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 POTS.
    How do I know if I’m eligible to be in this study? 
    Who pays for the exams, testing, and travel? 
    How can I get a questionnaire  for this study? 
    If I decide to participate what does the study entail?


    What comprises the study population? 

    We are seeking patients aged 18-29 years old with postural tachycardia syndrome (POTS) who may benefit from an investigation of abnormalities of regulation of  respiration and sympathetic nervous system regulation. Many people are unable to remain upright for long because of symptoms such as dizziness, nausea and headache or fainting. We and others have now shown that there is frequent upright increased breathing and shortness of breath in many POTS patients. This may occur on a day-to-day basis and may severely compromise lifestyle. The most common cause of this condition is the postural tachycardia syndrome (POTS), which is believed to affect at least a million Americans. POTS is defined by an abnormal increase in heart rate (“tachycardia”) that occurs when upright (therefore “postural”). POTS has many causes and we are attempting to determine the precise biochemical basis for POTS in patients.


    What is the hypothesis and importance

    We hypothesize that excessive baroreflex unloading during orthostatic stress (upright positioning) is the initiating event in POTS which results in two additional physiological consequences leading to hypocapnic hyperpnea (low carbon dioxide caused by markedly increased ventilation): a) reduced inhibition of chemoreceptor activity centrally and b) frank stimulation of peripheral chemoreceptor activity due to sympathetically induced reductions in blood flow to the carotid body. Increased chemoreceptor activity leads to hyperpnea which activates pulmonary stretch receptors. 

     Study Purpose: In this proposal we address the clinical problem of hyperpnea in orthostatic intolerance and propose a line of investigation which we hope will lead to better understanding of autonomic cardiovascular regulation in postural tachycardia syndrome.


    What are the symptoms of POTS

    The key feature 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). Shortness of breath is also frequently noted and can emulate asthma or other respiratory illnesses. These occur on a day-to-day basis. The symptoms overlap with the case definition of chronic fatigue syndrome (CFS) and POTS is often found in CFS in the young. Fainting is relatively uncommon during daily life. 



    What is the goal of the study

    Our study will determine how often respiratory abnormalities occur in POTS and their relationship to excessive activation of the  sympathetic nervous system, the branch of the autonomic nervous system that regulates blood flow and cardiac contraction.  Specific causes for POTS may vary from patient to patient. Patients will be compared to healthy control subjects. If we know the specific mechanism we may be able to offer specific treatment to specific patients.



    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 blood tests can be performed by your own physician. In addition you may have seen a cardiologist, a neurologist, or an endocrinologist. Tests such as tilt table tests may have been performed which is the standard means to diagnose POTS: POTS may have been diagnosed during a preliminary laboratory session by an increase in sinus heart rate of greater than 30 bpm within 10 minutes after upright tilt to 70° associated with symptoms of orthostatic intolerance.

    However, 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 such as avoidance maneuvers and by 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’m eligible to be in this study? 

    All POTS patients are elligible. It can be difficult to distinguish those with different causes of POTS prior to entry into the study. At this time we cannot accurately predict who has local circulatory dysfunction, or who has sympathetic activation. Therefore all patients who fulfill the criteria for POTS and are between 15 and 29 years old can enroll.

    The diagnosis of POTS may be made by your doctor or your consulting doctors. However,  this requires documentation of a standard tilt test demonstrating the changes in heart rate associated with symptoms of OI that are characteristic of POTS. The diagnosis of POTS may also be made through contact with our center which will include a standard tilt table evaluation. The diagnosis of POTS is prerequisite to the the study proper.

    Exclusion:  Criteria for initial exclusion will include a condition known to be associated with endothelial dysfunction, 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, or substance abuse within 2 years before onset of symptoms.

    Inclusion: Cases will be between the ages of 15 and 29 years old referred for evaluation of orthostatic intolerance with 3 or more of the following symptoms for at least 3 months: dizziness, nausea and vomiting, palpitations, fatigue, headache, exercise intolerance, blurred vision, abnormal sweating, heat. Cases will have the diagnosis of symptomatic postural tachycardia made during a screening tilt table test. 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.



    Who pays for the exams, or testing?

    The diagnosis of POTS is a clinical diagnosis that may be made by your doctors or by our center. In either case clinically appropriate fees may be incurred. There is no charge to you for any of the the testing  directly related to this study. We will pay each participant who completes the two day study $300 as a token of appreciation for their time.



    How 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 to stewart@nymc.edu or you can 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’ll mail you an application. 


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

    If you would like to take part in these studies, the study coordinator will contact you to go over questionnaire material and discuss arranging for the study. The study coordinator 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 study. 

    Testing lasts two days usually on a Monday and a Tuesday. We will make appointments to come to our center for your visits. You’ll arrive at 10 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 then you will meet Dr. Indu Taneja and Dr. Julian Stewart who, along with the coordinator or a technician, 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’ll answer a few questions, have a brief physical examination, give a urine sample, and be taken to the laboratory area.

    You will undergo tests of how the blood vessels and sympathetic nerves function.  We will measure blood flow properties of the leg and arm vein using noninvasive techniques while lying flat. We will measure regional blood flow with impedance plethysmography using electrodes similar to EKG electrodes. We will measure sympathetic nerve activity using a microelectrode in a leg nerve. We will also ask you to breath different concentrations of oxygen and carbon dioxide. You will have several brief tilt table tests. We will noninvasively measure brain blood flow with ultrasound. 

    We expect that each visit will take about 6-7 hours per day over two days of testing. 

    If you have further questions about the study, please feel free to call:
    914-593-8888 for more information. 
    or Email Indu_Taneja@nymc.edu or stewart@nymc.edu





Mechanisms of Vasovagal Syncope
Local Vasoconstriction and Sympathoexcitation in Postural Tachycardia Syndrome
Brain Fog in CFS and POTS
Vascular Dysfunction in the Chronic Fatigue Syndrome
Hyperpnea in Postural Tachycardia