In the absence of normal cardioversion resources, would it be possible and/or useful to lower someone's heart rate by ducking their face in cold water (i.e. activating the dive reflex)?
Yes, but only for one specific circumstance (and maybe not exactly how you’re thinking).
May I introduce you to my favorite arrhythmia: Paroxysmal Supraventricular Tachycardia (PSVT). I like it because its not too deadly, can be utterly terrifying, and there’s a lot of cool ways to treat it. One of the more common first line treatments for PSVT is the use of a vagal maneuver, one of which involves dunking one’s head in ice water.
There’s a lot of background I have to go through to explain it though, so bear with me:
Heart Electrical Stuff:
The heart rate and rhythm are controlled by structures in the heart capable of sending electrical signals (pacemaker nodes). When those nodes send out an electrical signal, it travels through the heart muscle across specialized fibers. As the electrical signal passes them, cells that are sensitive to that signal contract in sequence. This results in a coordinated beat.
If this electrical signal is discharged inappropriately or interrupted, the result is an abnormal heart beat, rate, or rhythm. Some of these abnormal heart beats, rates, and rhythms, especially ones that start in the lower part of the heart (the ventricles) can be deadly.
Fortunately, PSVT starts in the upper part of the heart (the atria), and is not deadly on its own. It occurs when one of the pacemaker nodes in the upper part of the heart (the SA or AV node) get “stuck” discharging signals too fast- sometimes as many as 250 times per minute.
Even though this likely won’t kill the person, it’s still a problem because when the heart beats too fast, it does not have time to completely fill with blood in between beats. This means not enough blood gets out to the body and brain, causing dizziness and shortness of breath (because enough oxygenated blood isn’t getting to the brain and body tissues, causing a slight lack of oxygen throughout the body). Some people can feel their heart beating abnormally fast, and some have chest pain with this too.
Treating PSVT (what you’re actually here for):
One of the first ways to treat PSVT is the use of vagal maneuvers.
Vagal maneuvers are different actions that can stimulate the vagus nerve- a nerve that connects the heart and lungs to the brain. When triggered, the vagus nerve releases neurotransmitters that can slow the heart rate set by the SA and AV nodes. In the case of PSVT, this might be enough to “break” the ultra fast heart rate and reset to a normal one.
Some vagal maneuvers include:
Bearing down (as though trying to poop)
Carotid massage (massaging the area of the carotid artery just below the jaw- this should only be done by trained professionals, though, as a last resort before moving on to more invasive treatment)
Submerging the face/head in ice water
See, told you we’d actually get to this. The dive reflex (which I should really do a whole post about, cause its super cool, uh, literally) is a trait that allows aquatic mammals to conserve oxygen and stay under water longer by significantly decreasing their heart rate and shunting blood into their core. Hitting one of the nerves in the face (the trigeminal nerve) with freezing water mimics this reflex in humans, which in turn triggers the vagus nerve, which is what helps treat the PSVT. Here’s my favorite PSVT home video about vagal maneuvers.
Just for funsies, I’m going to keep going. If vagal maneuvers are ineffective, the next step up is to use a medication called adenosine. Adenosine is given IV, where it is pushed as fast as possible into the vein. When it hits the heart, it briefly stops it. The hope is that it starts back up in a normal rate. Think chemical defibrillation. Here’s another one of my favorite PSVT video about adenosine administration.
People can have episodes of PSVT frequently or just once or twice in their whole lives. If it becomes a problem, certain parts of the heart can be cauterized to prevent future attacks.
Personal note: I’ve had four runs of SVT in my life, the longest one
lasting a little over an hour. All were eventually treated with vagal
maneuvers and I never had to be hit with adenosine or cardioversion, but if I ever do, I’ll certainly share my experience with you all.
If Styles hadn’t yet adapted to global social-media attention, he was tested in 2012, when he met Taylor Swift at an awards show. Their second date, a walk in Central Park, was caught by paparazzi. Suddenly the couple were global news. They broke up the next month, reportedly after a rocky Caribbean vacation; the romance was said to have ended with at least one broken heart.
The relationship is a subject he’s famously avoided discussing. “I gotta pee first. This might be a long one,” he says. He rises to head to the bathroom, then adds, “Actually, you can say, ‘He went for a pee and never came back.‘ ”
He returns a couple of minutes later. “Thought I’d let you stew for a while,” he says, laughing, then takes a gulp of green juice. He was surprised, he says, when photos from Central Park rocketed around the world. “When I see photos from that day,” he says, “I think: Relationships are hard, at any age. And adding in that you don’t really understand exactly how it works when you’re 18, trying to navigate all that stuff didn’t make it easier. I mean, you’re a little bit awkward to begin with. You’re on a date with someone you really like. It should be that simple, right? It was a learning experience for sure. But at the heart of it – I just wanted it to be a normal date.”
He’s well aware that at least two of Swift’s songs – “Out of the Woods” and “Style” – are considered to be about their romance. (“You’ve got that long hair slicked back, white T-shirt,” she sang in “Style.”) “I mean, I don’t know if they’re about me or not …” he says, attempting gallant discretion, “but the issue is, she’s so good, they’re bloody everywhere.” He smiles. “I write from my experiences; everyone does that. I’m lucky if everything [we went through] helped create those songs. That’s what hits your heart. That’s the stuff that’s hardest to say, and it’s the stuff I talk least about. That’s the part that’s about the two people. I’m never going to tell anybody everything.” (Fans wondered whether “Perfect,” a song Styles co-wrote for One Direction, might have been about Swift: “And if you like cameras flashing every time we go out/And if you’re looking for someone to write your breakup songs about/Baby, I’m perfect.”)
Was he able to tell her that he admired the songs? “Yes and no,” he says after a long pause. “She doesn’t need me to tell her they’re great. They’re great songs … It’s the most amazing unspoken dialogue ever.”
Is there anything he’d want to say to Swift today? “Maybe this is where you write down that I left!” He laughs, and looks off. “I don’t know,” he finally says. “Certain things don’t work out. There’s a lot of things that can be right, and it’s still wrong. In writing songs about stuff like that, I like tipping a hat to the time together. You’re celebrating the fact it was powerful and made you feel something, rather than ‘this didn’t work out, and that’s bad.’ And if you run into that person, maybe it’s awkward, maybe you have to get drunk … but you shared something. Meeting someone new, sharing those experiences, it’s the best shit ever. So thank you.”
Harry Styles talking about Taylor Swift - Rolling Stone May 2017 (x)