DESCRIPTION
In POTS, the different parts of the nervous system are out of balance. They do not work together as needed.
The nervous system can be divided into two parts:
- Central nervous system (CNS). The CNS consists of the brain and spinal cord.
- Peripheral nervous system (PNS). The PNS consists of the nerves that travel from the brain and spinal cord out through the body, and from the body back to the brain and spinal cord. The PNS itself can also be divided into two parts:
- Somatic nervous system. The somatic nervous system controls voluntary movement.
- Autonomic nervous system. The autonomic nervous system regulates functions of the body without conscious thought.
Role of the Autonomic Nervous System
The autonomic nervous system works to regulate involuntary, or unconscious, bodily functions. For instance, it can regulate breathing, even if we are not thinking about breathing. In addition to breathing, the autonomic nervous system regulates:
- Heart rate
- Blood pressure
- Sweating
- Digestion
The autonomic system is part of the PNS. However, some areas of the CNS can also activate or suppress the autonomic systems. Areas of the CNS that can impact autonomic systems include:
- The hypothalamus, which regulates hormones
- Parts of the brain that respond to emotions
POTS and the Autonomic System
Most of the time, the CNS works with the PNS to keep a balance, or homeostasis, among the systems. This leads to optimal functioning. In POTS, these systems are not working properly. This can affect blood pressure, which in turn can trigger many of the symptoms of POTS.
When a person stands up from sitting or lying, the autonomic system normally works to constrict blood vessels. This increases blood pressure and helps blood continue to flow to the brain despite the effects of gravity. When the blood pressure does not increase enough while standing upright, this is called orthostatic hypotension.
In POTS, the blood pressure does not drop when going from sitting/lying to a standing position—this occurs with the condition called orthostatic hypotension. When the autonomic nervous system is working properly, the blood pressure rises when a person stands. In POTS, when a person stands, the heart rate increases dramatically to keep blood flowing to the brain. This is call orthostatic intolerance.
While orthostatic hypotension indicates low blood pressure with standing, orthostatic intolerance causes unpleasant sensations, like instability, lightheadedness, and heart palpitations. This means that the autonomic system is not working properly. This might be due to a problem with the CNS or the PNS.
SIGNS AND SYMPTOMS
Symptoms of POTS can include, but are not limited to:
- Orthostatic intolerance (difficulty standing upright)
- Tachycardia (rapid heart rate)
- Lightheadedness or dizziness
- Fatigue
- Anxiety
- Nausea
- Headache
- Problems with concentration, focus, and memory
- Syncope (fainting or passing out)
- Intolerance of heat or cold
- Somatic hypervigilance (perceiving normal sensations as intense or distressing)
DIAGNOSIS AND LABORATORY INVESTIGATIONS
POTS is diagnosed clinically. There is no blood test or imaging that can confirm a diagnosis of POTS. However, a doctor may do further testing to look for diseases that might be an underlying cause of POTS.
A clinical diagnosis can be made in a doctor’s office using heart-rate testing.
- The patient will be asked to lie down.
- Heart rate and blood pressure will be monitored during rest.
- Heart rate and blood pressure will be measured again after standing.
Heart-rate testing can be done in any doctor’s office. Sometimes a neurologist may perform a tilt-table test to measure heart rate and blood pressure with other changes in position. This is the best test for a diagnosis of POTS, but may not be as accurate in children, or adults who have short stature.
Criteria for a POTS Diagnosis
A POTS diagnosis is related to having a rapid heart rate (“tachycardia”) while in an upright position (“postural orthostatic”). The exact criteria are as follows:
Children and teenagers
Adults
If a patient has low blood pressure when standing up, but no increase in heart rate, they may be diagnosed with orthostatic hypotension, not POTS.
OUTLOOK
Most people with POTS have some recovery within 1 to 5 years of using first-line treatments. However, some symptoms may not resolve. Adolescents with POTS may have recurrences later in life.
