Like everything else, your blood is subject to the laws of gravity. When you stand up, gravity pulls blood into your abdomen and legs.
To counteract this effect, your leg muscles help pump blood back to the heart, which speeds up slightly with the help of a boost of adrenaline. A burst of norepinephine constricts blood vessels to further guide blood back to the heart and, in turn, the brain. If you’ve ever had a rush of dizziness when standing too quickly, you’ve experienced a momentary delay in this normally elegant system. If you have postural orthostatic tachycardia syndrome (POTS), there’s more than a delay: The mechanisms designed to avoid blood pooling into your abdomen and legs fail.
A faulty system
The longer you stand, the more the blood pools. Your body still tries to correct the pooling by releasing norepinephrine and epinephrine, which cause your heart to beat faster, but the blood vessels don’t constrict as they’re supposed to. The pooled blood isn’t returned to the heart, which creates a chain reaction where insufficient blood gets to the brain, causing symptoms such as lightheadedness, nausea, vomiting, dimmed vision, altered hearing, and fainting. The heart tries to compensate by beating faster, leading to an elevated heart rate (called tachycardia).
The reaction can be triggered by standing, sitting at a desk, standing in line, taking a shower, and seeing blood or gore. It can occur in people who overly restrict their salt intake or don’t drink enough water—both of which help maintain healthy blood pressure by retaining fluid in blood vessels. Being overheated, scared, or anxious are triggering factors as well.
While there’s not yet a cure for POTS, there are a variety of treatments and strategies that can minimize its effects on daily life.
Many people with POTS have low blood volume, which can often be rectified by increasing salt and fluid intake. At the Vanderbilt Autonomic Dysfunction Center, we recommend eating 6 to 9 grams of dietary salt and drinking 2 to 3 liters of water each day.
Follow a low-carbohydrate diet, and avoid large meals that divert blood flow to digestive organs. Small, frequent meals are a better option. It’s also wise to avoid alcohol, which causes veins to dilate.
While the corsets of yore caused an epidemic of fainting spells, a modern take on abdominal compression can decrease blood pooling. Abdominal binders or back braces that can be loosened when sitting and then tightened when standing are good options. Waist-high compression stockings can also help if they have at least 30 to 40 millimeters of mercury of compression, but they can be both difficult to put on and uncomfortable to wear.
Posture and movement
When POTS symptoms strike, you may be able to move in ways that can help reduce blood pooling.
- Stand on your toes, cross your legs, or put one leg on a chair when standing.
- Flex your leg and buttocks muscles.
- Sit in a low chair, in a knee-chest position, or with your feet on a footstool.
- Lean forward when sitting.
- Bend forward at the waist when walking (such as when you’re pushing a shopping cart).
- Slightly elevate the head of your bed to retain fluid at night.
- If you feel faint, grip one hand with the other and push your arms away while contracting your muscles for two minutes.
While exercise can worsen POTS symptoms at first, a program that builds tolerance can yield dramatic benefits. Patients who could only tolerate a minute or two of activity have been able to build up to vigorous 45-minute workouts over time. The key is to start small and be patient.
Even if you are bedridden, you can start with simple exercises that can be done while reclining:
- Put a pillow between your knees, squeeze for 10 seconds, release, and repeat.
- Repeat the same exercise with the pillow between your palms.
- Write your name in the air with your toes. Over time, work on the whole alphabet.
- Lie on your side, lift your leg up sideways, and bring it back down without touching your legs together. Repeat.
- Lie on your back, lift your left leg up, and point your toe towards the ceiling. Switch legs and repeat.
- Mildly stretch your whole body, starting with your feet then moving to your legs, back, arms, and neck.
For a more challenging workout, look to recumbent exercises, such as recumbent biking or rowing, that allow you to work harder without triggering the POTS response.
Swimming keeps you in a reclined position and builds strength in your legs, which itself can reduce orthostatic symptoms. Because the pressure from water helps prevent orthostatic symptoms, some people with POTS can even stand for lengthy periods in a pool.
Weight training increases strength and helps muscles more efficiently use oxygen and tolerate orthostatic stress. Start with light weights and use them in a reclined or seated position. Focus on the muscles in your legs and abdomen. Lifting your arms over your head can aggravate symptoms.
As your fitness increases, you may be able to work up to upright activities like walking, jogging, or biking. Avoid outdoor exercise when it is hot, and always warm up and cool down. Taking the medication propranolol may improve your exercise capacity.
If lifestyle strategies don’t ease your symptoms, medications may help. Drugs like fludrocortisone (Florinef) and midodrine (Proamatine) can increase blood volume and blood vessel contraction, which can help return blood to the heart. Beta-blockers such as metoprolol (Toprol XL, Lopressor), atenolol (Tenormin), and propranolol (Inderal LA) can slow down the heart rate upon standing. If these medications fail, verapamil (Verelan, Calan SR) or ivabradine (Procoralan) can be added for additional heart rate control.
For patients who have symptoms such as flushing, excessive sweating, and jitters, medications such as clonidine (Catapres) and guanfacine (Intuniv ER) that reduce the release of or response to epinephrine and norepinephrine can help.