Medically, why are panic attacks and heart attacks so similar?

I suffer from frequent severe panic attacks and I’m constantly having to talk myself out of the notion that I’m having a heart attack. It may sound silly but they share a lot of symptoms, such as:

Palpitations and a racing heart rate.
Chest pain.
Pains, numbness, heaviness/weakness and tingling in the left arm (or any extremity, but for me it always seems to be the left arm.)
A sense of impending doom.

Why are the symptoms so similar? I mean, I get why a panic attack would trigger a sense of impending doom but why would a heart attack do that? If that sounds like a silly question, bear in mind that for a lot of people a sense of doom is one of the first symptoms they get, before chest pain or nausea or anything else. There must be something physical going on. What is it?

I ask because I’m sick of having to talk myself out of the notion that I’m having a heart attack. I’ve had a ton of tests (bloods, echo, treadmill, 72 hour tape, countless ECG’s) and they’ve all come back normal, but when the panic attacks come on all of that reassurance is suddenly worth jack shit.

So yeah, since I know nothing about biology, I’d really appreciate it if any medical people on the boards could explain (a) why the two are so superficially similar, and (b) is there any reliable way I can tell the difference between the two in the moment?

Thanks very much in advance.

While the underlying causes are very different, they make similar things happen in your body - namely, a lack of oxygen where there should be oxygen. The big difference being that panic attacks are short lived and do no lasting harm, while heart attacks may result in permanent harm.

Panic attack: You begin to hyperventilate and adrenaline surges, which increases the heart rate. The heart sometimes beats so fast that it’s not actually filling with enough blood between beats, and the breathing is happening so fast that oxygen can’t cross through your lungs into your blood. Together, these cause a low oxygen level in your brain (creating a sense of impending doom and nausea) and in your heart (causing chest pains) and in your extremities (causing pain and tingling in your arm).

Likewise, many of the symptoms of a heart attack are due to low oxygen in precisely those same places, only in the case of a heart attack, it’s because oxygen is cut off to a part of the heart by a clot or a spasm in a coronary artery. But the symptoms then proceed the same way…low oxygen to the brain causes that impending doom and nausea, your body releases adrenaline to make your heart beat faster to make up for the low oxygen, creating a rapid heart beat and palpitations and it’s still not getting enough oxygen, causing chest pains, and your extremities begin to tingle and pain.

If you are a young, healthy, fit person with a known history of panic attacks and a low risk of heart attacks, you can try to control your breathing. Breathing into a paper bag is the classic way, but breathing with your hands cupped around your nose and mouth works, too. If you can slow your breathing and your symptoms go away, then you’re probably looking at a panic attack, not a heart attack. If you have panic attacks a lot, then you should speak with your doctor about how to reduce them through biofeedback or medication.

But the only way to know for *sure *is to have blood taken in the ER. They’ll look for proteins in your blood that are only released when heart muscle is damaged. If they find them, then it’s a heart attack. If they don’t, they can do some other tests to make sure your heart is getting enough blood flow.

Never hesitate or be embarrassed to go to the ER if you think it might be a heart attack. Everyone loves a false alarm (really!) because it’s one case where, truly, better safe than sorry.

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Medical questions belong in IMHO. As the forum name indicates, any replies you receive there are just the opinions of some online folks, and should not be taken as a substitute for professional medical advice.

Moving thread from General Questions to In My Humble Opinion.

Wait a minute. If the problem is lack of oxygen in the brain, then how does breathing into a paper bag help? All that’s gonna do is supply even less oxygen to your lungs (and thence brain).

Why don’t these same things occur with strenuous exercise? By and large, people’s hearts beat faster when they’re exercising than during a panic attack. Yet, people don’t (usually) die during exercise.

Adrenaline, or nor-epinephrine is what causes the impending doom feeling I think.

Excellent question! Because there’s no time for oxygen exchange across the alveolar membranes when the respiratory rate is too high. While exchange is quick, it’s not instantaneous. So hyperventilation leads to lower Pulseox readings. Slow 'em down, and they oxygenate better. Put 'em on oxygen (so there’s a higher percentage of oxygen with each breath) and they oxygenate better. The latter’s not quite so useful at home, of course.

Matter of degree. Certainly I get light headed, heat pounding and tingly extremities and feel like I’m gonna die with strenuous exercise. But that’s because I’m only in shape in the sense that round is a shape. For people that exercise regularly, their respiratory systems and cardiovascular systems adapt - the heart has a slower resting and exercise rate and higher cardiac output, and the surface area of the alveoi, as well as the pulmonary volume, increase for quicker oxygen/carbon dioxide exchange.

I see. Thanks for the explanation. I’m still confused about one thing, however. As I understand it, panic attack symptoms stem from hyperventilation. The strange thing is that when I have a panic attack I don’t hyperventilate. I learned breathing control exercises and I also take a beta blocker to help control the somatic symptoms but in spite of this I still get symptoms (thumping palpitations, sweating, nausea, dread, chest and arm pains etc…). Also, my attacks can wax and wane for several hours. Could there be any other reason for this apart from hyperventilation?

There could be, but that’s a question better answered by your doctor who knows your history and labwork.

(Excess thyroid hormone is where I’d start looking, though.)

Are you stating that breathing into a paper bag will slow down someone’s breathing? Because the treatment you described, and that I was commenting on, was breathing into a paper bag

Okay, here’s my take on it:

When a person hyperventilates, they blow off carbon dioxide to excess (and, if anything, increase their blood oxygen). As a result of the low levels of carbon dioxide, the blood becomes more alkali (more negatively charged) and that has several effects.

For one, the blood vessels to the brain become constricted (and, theoretically, that could lead to some changed mentation or even panic).

Secondly, and I think more importantly, when the blood is alkali, positive hydrogen ions diffuse off of blood proteins in attempt to offset the change in blood pH. That leaves the proteins negatively charged, and the negative charges on the protein bind to blood calcium (with calcium being a positive ion). As a consequence, blood levels of (free) calcium drop and the person experiences the symptoms of low blood calcium (hypocalcemia). One of the primary symptoms of hypocalcemia is tingling of the extremities and around the mouth. Those are weird sensations and can thus promote more panic, leading to more hyperventilation, etc.

Breathing into a paper bag prevents the person from blowing off even more carbon dioxide (it has nowhere to go!) so its blood levels rise again and thus blood pH normalizes. Then, (free) calcium levels in the blood return towards normal. As that happens, the tingling stops. The person then calms down and stops breathing so rapidly. All better. (for now)

In my late 20’s and early 30’s I suffered from panic attacks that mimicked heart attacks. A strong pain going through the left side of my jaw and down into my arm were very common. Pressure on my chest like someone was sitting on it.

I figured it out and cured it. I often gave my Dr credit for this because I doubted anyone would listen if I said I found it. I would check my saliva durring a panic attack to see if it was foamy, if it was foamy I know I have been swallowing excess air. The cure was simple, hold a handkerchief in my hand and wipe my mouth repeatedly instead of swallowing until it subsided which usually took under 15 minutes.

I want to kiss you and hug you and all that good stuff. I had years of panic attacks and medications and no one ever explained them to me. Thank you so much.

That’s not what I was taught in nursing school, although some of it sounds plausible. And I’ve definitely verified the low pulseox readings when a person is hyperventilating and seen the number go up as I coach them through slow breathing or cupped hand breathing (I’ve never actually had a paper bag at hand to try it.)

Excess carbon dioxide (from not breathing enough of it out while hyperventilating) may be causing the tingling, though, rather than too little oxygen. As I recall, excess carbon dioxide is extremely painful.

Your explanations of medical stuff are usually very good but you’ve got this rather backwards.

To reiterate - acute hyperventilation causes increased alveolar ventilation and you blow off CO2 faster than your body produces it, creating a primary respiratory alkalosis. Your body autoregulates cerebral perfusion based partly on arterial CO2 levels. Decreased CO2 causes cerebral vasoconstriction.

From UpToDate: “Cerebral blood flow decreases in a linear fashion with decreasing PaCO2: a decrease of 1 mmHg of PaCO2 is associated with a 2 percent decrease in cerebral blood flow. A reduction in cerebral blood flow in the setting of hyperventilation, hypocapnia, and respiratory alkalosis may explain the neurologic symptoms associated with the hyperventilation syndrome such as paresthesias, headache, and light-headedness.”

As an aside, the cerebral pefusion response to hypocapnia is why we sometimes use hyperventilation as a salvage measure in cases of intracranial hemorrhage. If a patient with ICH is showing signs of impending herniation we hyperventilate them to decrease cerebral perfusion, decrease the bleeding and hopefully keep them from herniating while they’re rushed to the OR for an emergent craniotomy.

Alkalosis provokes other changes in blood chemistry. It causes increased binding of calcium to albumin creating an effective hypocalcemic state even though total serum calcium doesn’t change.

From UpToDate: “The hallmark of acute hypocalcemia is tetany, which is characterized by neuromuscular irritability. The symptoms of tetany may be mild (peri-oral numbness, paresthesias of the hands and feet, muscle cramps) or severe (carpopedal spasm, laryngospasm, and focal or generalized seizures, which must be distinguished from the generalized tonic muscle contractions that occur in severe tetany)…Respiratory alkalosis alone (eg, hyperventilation) can cause tetany, even in the absence of underlying hypocalcemia.”

Alkalosis also causes intracellular shift of potassium and phosphorus that may result in serum hypokalemia and hypophosphatemia. Hypokalemia can cause muscle cramping but most sources attribute the muscle cramping sometimes seen with hyperventilation to hypocalcemia rather than hypokalemia.

The primary association between low O2 and hyperventilation is that hypoxemia provokes hyperventilation. I can’t find any sources that list low O2 as a cause of hyperventilation symptoms. I did findthis abstract which states that O2 levels rose during hyperventilation and then fell to below baseline 5 minutes after hyperventilation ended. This abstract also reports increased O2 during hyperventilation and post-hyperventilation hypoxemia. More relevant for your personal experience of observing low sats in a hyperventilating patient it includes the statement that “Noninvasive transcutaneous blood gas measurements are not reliable for monitoring blood gas changes during and after hyperventilation, most probably because of the slow response time of the electrodes and the reflex vasoconstriction of the skin vessels.”

IOW, what I said (and somewhat more succinctly ;)).

Dittos, minus the desire to hug and kiss. I find that if a PA is coming, just to breathe slowly and deeply.

Which is why I started my explanation with “to reiterate”. But WhyNot didn’t seem convinced so I stuck in some more detail on the physiology and a couple of cites. I also wanted to see if I could find an explanation for her personal observation of low sats during an episode of hyperventilation since that conflicts with what should be happening. Anyway, it was a nice review of acid-base physiology and I learned about post-hyperventilation hypoxemia. And it was more interesting than dealing with the 30 or so resident notes in my inbox from yesterday.

Sorry, I didn’t mean to appear snarky. Mostly, I was letting out my frustration retroactively, i.e. it was as if everyone who read the thread (until you) had me on ignore.

BTW, I also was trying to come up for an explanation of why O2 sats could drop as a result of hyperventilation. The only thing I could think of was that perhaps the sat monitor had slipped off the finger due to all the movement from the respirations. Although I meant it seriously and in good faith, I resisted posting it lest it be interpreted as sarcasm. In any case, I honestly don’t know how oxygen sats could drop because of hyperventilation (i.e. they can definitely drop in tandem with hyperventilation if, say, the the hyperventilation is being caused by a huge shunt or if the hyperventilation is still inadequate for the degree of shunt, etc.)

Okay, so having established that the first answer was a bit off … hyperventilation causes symptoms* not* primarily because of low oxygen or high carbon dioxide levels but because it blows off carbon dioxide causing acid-base imbalances that are the prime cause of many of the symptoms directly impacting how nerves function and causing spasms of some small muscles, and that initially oxygen levels may increase during a panic attack … let’s return to the now unanswered op.

Some may be just coincidental overlap. The arm pain in a heart attack is referred from the heart itself; the tingling in hyperventilation occurs in the nerves and muscles from the acid-base imbalance. The fast breathing in a heart attack may be from fluid in the lungs whereas it is more primary in hyperventilation.

My guess however is that some overlap shares a cause … the hormonal responses and their impacts on brain function. My first guess, an adrenergic surge, seems to be wrong. It does occur with heart attacks but surprisingly not with panic attacks. It may however actually be a shared decreased parasympathetic response … interestingly nutmeg overdose (through anticholinergic, i.e., decreased parasympathetic, activity) can also cause that sense of doom. Apparently decreased parasympathetic activity occurs early on in MIs and if increased sympathetic activity is not causing panic attacks then decreased parasympathetic likely is.

What do the informed here think of that speculation?

From the observer point, I’ve seen panic attacks and actual heart attacks, and they are not all the much alike. Of course to the person suffering from panic, I would think they are.

Overbreathing as stated, is causing most of these issues with panic. I found teaching people to simply close their mouths and breath through their nose, will be similar enough to breathing into a paper bag.

For heart racing, massaging the carotid artery works well, though only do this one side at a time. Similar to that you can dunk your face in a pale of ice water and that will stun the system back into line or you can try to bear down like you are having a painful bowel movement. Both these actions put the body into a motion where it slows a racing heart.