What Causes the High Heart Rate in POTS?

Most explanations of POTS describe the fast heart rate as something that happens for reasons nobody fully understands, or as a nervous system that overreacts. That leaves you managing a number without knowing what it's for.

Our team starts from a different place. The heart rate rises for a reason, and the reason is blood flow to your brain. Once you see the heart rate as a rescue, the rest of POTS, from the beta blocker question to what's worth measuring, starts to make sense.

Why the Heart Speeds Up: A Rescue for Brain Blood Flow

Start from the beginning. When heart rate rises in POTS, what is it doing? It's a rescue mechanism. Your body is trying to get more blood, and more oxygen, to your brain. It's the same thing that happens any other time your heart speeds up. Walk up a steep hill and your heart rate climbs because it needs to pump blood faster to reach your muscles and your brain so you can keep walking. In POTS the same logic applies, even though nothing about standing in the kitchen feels like exercise. The heart is delivering more blood supply to tissues that aren't getting enough.

What changes in POTS is that the whole delivery system has become inefficient. When it's inefficient, the body has to reach for more effortful rescue techniques to keep the brain supplied, and cranking the heart rate is the loudest of those. Our team has covered why the heart rate climbs when you stand and where the tachycardia comes from. This article looks at what that rescue tells you and what to do with it.

Why Inefficient Systems Go From Specific to Generalized

There's a neurology principle underneath this. When a system becomes inefficient, the thing you notice is that movements that should be very specific become generalized. Reach for a notebook and a healthy nervous system stabilizes the spine, reaches with the arm and grasps with the hand, and that's the whole job. In someone with a movement disorder like dystonia, the intent to move just the hand leaks into the neck, then the trunk, until far more of the body is involved than the task needs. None of that extra movement is necessary. It happens because the signal from brain to hand is getting spread out.

Blood flow around the body, hemodynamics, is another movement pattern. Lose efficiency there and you have to compensate somewhere. If the body isn't squeezing blood back through the venous system, or it's pooling in the wrong places, or your breathing is off and the carbon dioxide shift is narrowing brain vessels, or the brain isn't managing flow well, then a different system has to pick up the work at a higher energy cost. The heart rate is that generalized compensation. It's the neck and trunk getting dragged into a job that should have been done by the hand.

It's also why your heart rate changes from day to day, and why those changes are worth paying attention to. You rode in the car yesterday with your head cranked to one side for an hour, took in a flood of visual stimulus, and irritated a piece of that system. Today the efficiency of sending blood is different, so the heart works harder. There are dozens of reasons like that. The point is that it can change, and the difference between the 2 states is a pointer to where the problem lives.

What Beta Blockers Reveal About the POTS Heart Rate

One of the clearest places to see all of this is when the heart rate is changed artificially. A beta blocker blocks the signals that let the heart catch up, compensate, and rescue you. Take that compensation away and what happens? In some people the number drops and they feel a little better, because all the secondary consequences of a racing heart, the jitteriness, the anxious edge, quiet down. That's real and it can feel calming.

But look at the problem the heart rate was trying to solve. Did that get fixed? A lot of people notice a peak in those secondary symptoms and no change in what they can actually do. In many cases capacity gets worse, because the one thing the body was doing to maintain circulation is now unavailable, and the circulation pays for it. The research matches this. In a randomized crossover trial of 54 POTS patients, a low 20 milligram dose of propranolol reduced tachycardia and improved symptoms over 2 hours, while a higher 80 milligram dose lowered heart rate further and didn't improve symptoms any more, and may have worsened them. The authors titled the paper "less is more."

A second study from the same era compared 4 weeks of propranolol against 3 months of exercise training in POTS patients. Both lowered standing heart rate. But propranolol lowered standing cardiac output, and only training improved quality of life. Lowering the number is easy. Restoring the circulation the number was compensating for is the actual win, and when it happens, people move off the ceiling where they could not do more than a certain amount and start regaining ground. Our team's position on medication in POTS is the same as it's here: useful, with a ceiling.

If Not Heart Rate, Then What? Brain Blood Flow

So what should you look at instead? It's very convenient to wear something on your wrist or in your ear that hands you a daily score, and our team isn't against that. But the measurement that actually predicts what the rest of the body is going to do is blood flow into the brain. Getting blood to the brain is one of the most important problems your body has to solve, second by second, for your whole life. If you understand how well that's being solved, you have a much higher predictive value for everything downstream, including the heart rate.

Unfortunately no wearable can measure it. It takes transcranial Doppler during a tilt test, which is why our team measures it. The published data point the same direction. In a 2020 study of ME/CFS patients, many of whom met POTS criteria, the reduction in brain blood flow on tilt was 26 percent versus 7 percent in healthy controls, and the total symptom burden rose in a straight line with the size of the drop. The blood flow, not the heart rate, was the number that tracked how people felt.

Should You Track Your Heart Rate With POTS?

Yes, track it, because you may find real patterns. Just don't check it all the time. When a tracker hands us a score, how we feel starts to depend on the score. In a controlled experiment on people with insomnia, researchers gave participants sham feedback about their sleep from a wearable, randomly telling them their sleep efficiency was good or poor. The fake number changed how sleepy, how sharp, and how well they said they felt the next day. That study was about sleep, not heart rate, but the mechanism doesn't care what the metric is. If you're told your number is great, you tend to assume you're doing better.

So the trick is to track daily and look weekly. Review the trend in retrospect instead of reading the live number and deciding how your day is going to go. Heart rate is one data point in a constellation, and zooming out to the whole picture is what gives you room to actually progress instead of reacting to the watch.

The Subjective vs. Objective Gap in Dysautonomia

In 2024, researchers at the Brigham and Women's autonomic laboratory asked a simple question with a large dataset: do the symptoms people report line up with what autonomic testing measures? They compared validated symptom questionnaires with standardized autonomic tests in 2,627 patients. The subjective instruments agreed with each other. The objective instruments agreed with each other. And there were no meaningful correlations between the 2. How people felt wasn't predicted by how big the measurable abnormality was.

That sounds discouraging until you apply it to your watch: how you feel and what a single number shows can move separately, so no one reading can tell you how your day or your recovery is really going. Our team has written about why POTS symptoms so often fail to match test results, and this is the same lesson from the other direction.

What to Do With This

Stop grading how you feel on a given day by how high your heart rate went. Ask instead: how well is the blood flow to my brain being rescued today, and is my heart rate playing a role in that? That question gets you somewhere. It moves you from managing a number toward working on the capacity underneath it, and from our team's perspective, greater capacity is where everyone wants to go.

If you want a walk-through of that process, one that looks beyond the cardiac system rather than segmenting you by specialist, the free POTS roadmap below is where to start. It may give you enough education to figure out where your breakthrough is going to come from, and it doesn't replace medical advice.

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