Why skipped heartbeats always seem to happen at the same point in your menstrual cycle.

For those articles where there’s such overwhelming study findings that I feel comfortable presenting information as fact, I won’t put a “byline” picture at the top of the article.

You’ll see there’s a byline picture on this article. And with that byline I’m hoping you’ll let me express some frustration with the medical community. Palpitations, PVCs, PACs and other various arrhythmia are suffered by a huge portion of the population. Huge. And there are thousands upon thousands of pages on the web of women suffering through arrhythmia that seems to coincide with their cycles, and nobody’s able to provide them with a straight answer for why it happens.

The medical community just collectively pats women on the head, says “everything will be ok,” then sends them on their way. And nobody’s ever made to understand WHY this is happening. I even read an article by the female director of women’s cardiovascular health at University of Pennsylvania. [1] I mean, you can’t even dream up a better resource, right? She provided responses no better than you’d find at Yahoo! Answers.

Why is there no science on this topic? Why no studies? The results of those studies and presenting the science in lay terms would probably add hundreds of thousands of productive hours back into the lives of women across the world, instead of having them take time away from career or family, either at a doctor’s office or just withdrawing from the world for fear of dying of cardiac arrest.

That seems worth the effort and expense of a single study and comprehensive, scientific breakdown.

But we don’t have that. So I’ve gone over, under and through the web to find and piece together as much information about female menstrual cycles and causes for arrhythmia. The results of that research I present here. I hope it can give you some degree of peace.

Before I get too deep into how a woman’s menstrual cycle might affect heart rhythm, I think it’d be worthwhile to have a refresher on how it is, exactly, that a heart is able to beat. Just like every other muscle cell in your body (arms, legs), each cell in your heart holds a tiny little electrochemical charge (think of your car battery and the sloshy fluids inside it - same sort of thing). When that cell is ready to discharge, it becomes permeable by other electrolytes (like sodium ions (Na+)). When those electrolytes rush into the newly permeable cells, it starts an electrochemical chain reaction, moving from cell to cell to cell, resulting in the coordinated contraction of the muscles in your heart, squeezing to pump blood to the rest of your body.

That’s how your heart works. And I feel more than a little ridiculous, being a man, about to explain how the menstrual cycle works. But here I am, doing it anyway. At least a part of it.

As the female body performs it’s monthly task of preparing for pregnancy, making conditions optimal for creating a baby, then purging all evidence of that preparation (only to do it all over again the next month), hormones are coursing through a woman’s veins. During the first phase (of two) in the cycle, the follicular phase, the level of estrogen in the body is increased up until the point that it peaks, at ovulation. Post-ovulation, the amount of estrogen in the body decreases. Part of the reason that occurs is because the estrogen did it’s job: it initiated ovulation. The other part of the reason estrogen levels decrease is because (as is hypothesized by some in the medical profession), progesterone levels in the body increase just prior to ovulation, peaking in about the middle of the luteal phase (second phase) of the menstrual cycle. The theory is this: progesterone aids the body in metabolizing excess estrogen or as an antagonist to it’s production [2], so as progesterone levels increase, estrogen levels decrease. (I should note that the graphic here, courtesy of Wikipedia, seems to counterindicate that relationship between progesterone and estrogen levels. But for this discussion about heart rhythm, it isn’t relevant, so I won’t do anything beyond mentioning that I question the validity of the hypothesis about metabolizing estrogen with progesterone.)

And every month, this hormonal battle is waged within a woman’s body.

So. How does this relate to heart rhythm and palpitations? It wasn’t until I found a power point presentation on the American Heart Association’s website discussing the use of progesterone as a possible treatment for Long QT Syndrome (LQTS) that I was able to find other data points and start putting a few pieces together.[3]

According to Cardiovascular Research, a magazine of the European Society of Cardiology, women have a slightly longer QT interval than men when corrected for heart rate (QTc), which is to say that women also have a slightly higher heart rate than men.[4]

The article stated that for women at risk of suffering an episode of torsades de pointes (a type of extremely dangerous ventricular tachycardia), those episodes almost never happened during the luteal phase of the menstrual cycle, suggesting a tie between progesterone and the rate of repolarization of ventricular heart cells. As a refresher, if ventricle cells are slow to repolarize (regain their electrical charge), they may not be ready to initiate muscle contraction when needed, meaning blood pushed into them from the atria doesn’t get pushed from the ventricles into the body in a timely fashion. Also, it can result in ventricle cells being asked to depolarize (begin the process of contraction) right at the moment they are repolarizing - this is what can initiate torsades de pointes, which can turn into ventricular fibrillation, which is deadly without medical intervention.

But I don’t mention all that to scare you. Torsades is extremely rare, and is more common in heart attack survivors than the general population (because of the electrical problems associated with the tissue death that accompanies a heart attack), and also tends to be hereditary. I only mention it to show that the effect of progesterone on the cardiac system of the female body has been investigated.

In other studies there was indication that progesterone enhanced action potential adaptation during rapid heart rates.[3][5] In English? A woman’s tiny batteries in each heart muscle cell recharged faster in the presence of progesterone. Again, the study was relative to the problems associated with Long QT Syndrome, something that in all likelihood most all readers of this article do NOT have.

But the relevant part in my mind is that repolarization happened more quickly, making each of those heart cells ready to discharge and initiate a contraction earlier. If some of those cells are already predisposed to discharging early due to having a lower electrochemical threshold (the permeability I mentioned earlier), then those cells are just sitting there, all charged up, ready to set off a PVC, and they have an itchy trigger finger.

The result? A woman potentially getting more PVCs and palpitations during certain parts of her monthly cycle, every cycle. And for women who are taking birth control pills, this is likely to be exaggerated due to the increase in hormone levels from ingesting the pills.

Because there can literally be a hundred different reasons why a person experiences skips and flutters, the monthly increase in progesterone might not always be enough to cause skipped heartbeats. Maybe that month the person is under less stress and there’s been a lower quantity of catecholemines (a stress hormone) flowing through the body. Or other electrolytes are in better balance. Or she’s gotten enough sleep. Really, the reasons are too numerous to list.

But the doctors were right. Getting skips and bumps in your heart rhythm during the same part of your cycle is not an indication of anything sinister. In fact, it’s a sign that your reproductive system is working the way it’s supposed to, that progesterone is being produced, and that it’s making your heart a little jumpy. That’s all.