Welcome to Dr. Warrick's podcast channel. Warrick is a practicing cardiologist and author with a passion for improving care by helping patients understand their heart health through education. Warrick believes educated patients get the best health care. Discover and understand the latest approaches and technology in heart care and how this might apply to you or someone you love. Hi, my name is Dr. Warrick Bishop and I'd like to welcome you to my podcast and videocast station and to the Healthy Heart Network. Thanks for tuning in. Today I'd like to talk a little bit about something I was asked to provide some information on and that is supraventricular tachycardia. Supraventricular tachycardia. Well, first of all, let's define what supraventricular tachycardia is. It's a long word. Supra means above. Ventricular is referring to the main pumping chamber of the heart. Tachy means fast. Cardia means heart. Supra, above. Ventricular, above the main pumping chamber. Tachy, fast, heart. A fast heart that arises from the chamber above the main pumping chamber. That can only be a fast rhythm arising in the atrium. So supraventricular tachycardia in common talk, common speak, means a fast heart that's occurring in the atrium. Okay, so... How do we think about fast hearts in the atrium? Well, the atrium can beat rapidly, either irregularly or regularly. If it beats rapidly and irregularly, then this is generally a condition called atrial fibrillation. The heart loses its synchronicity. atria loses its synchronicity and it if you like twitches or vibrates or the word we use is it fibrillates and it fires off lots of electrical activity which heads down to the main pumping chamber of the heart stimulating that heart to beat rapidly so a rapid irregular pulse is atrial fibrillation I'm not going to talk too much about atrial fibrillation because, well, quite frankly, I've written a book about it. If you want lots of information, you can have a look at the book, which I know will be available from bookstores, but also your local library if you go and ask for it. So atrial fibrillation is a supraventricular tachycardia, but it's a fairly specific one and it's really a topic of its own. So I'm going to move that to one side. The other type of... supraventricular tachycardias are related to regular rhythm and those regular rhythms are really related to short circuits occurring so as the electrical impulse passes really from the top of the heart to the bottom of the heart there becomes a short feedback loop and the length of that feedback loop to some degree can determine the cyclical speed or the re-entry speed of a short circuit that then fires off extra beats giving rise to the electrical impulses that give rise to the fast heartbeat. There are three main short circuits I'd like to mention which can be associated with regular supraventricular tachycardia and in general terms I might just say in cardiological speak When we say SVT, supraventricular tachycardia, we're normally talking about the regular rate, not the irregular atrial fibrillation type supraventricular tachycardia. So we often talk supraventricular tachycardia. We're most likely talking about these three types of regular rhythm, generally not the irregular rhythm. We call that atrial fibrillation, although strictly Based on terminology and definition, it is an SVT. So the SVTs that I'm going to talk about are, one, atrial flutter, which is very closely linked to atrial fibrillation anyway, and I mention it in the book. But atrial flutter is a short circuit where the short circuit loop is occurring in the right atrium, very close to the tricuspid valve. This short circuit loop is very specific and it gives rise to a heart rate. which we see regularly, bang on 150 beats a minute. And it gives a very characteristic ECG as well. I won't talk about the ECG, but if you're a medical person, the term sawtooth is used. But it's a very specific flutter wave. The other type of supraventricular tachycardia is a paroxysmal saw where the short circuit loop tends to be close to that node. the node that connects the atria to the ventricles where the electrical current flows through that's the atrio ventricular node so the av node so if you've got a short circuit close to that then that looping short circuit can fire off electrical impulses at a rate of somewhere around 160, 170, 180, 190 beats per minute, sometimes faster, but generally in that order. It's very rapid. The last SVT that's really important to recognize is when there's an aberrant conduction or a connection, an aberrant connection between the top of the heart and the bottom of the heart. Generally, a muscular band exists between the atrium. and the ventricle and this bypasses the normal electrical pathway through the atrioventricular node. The atrioventricular node sort of protects the ventricle from very fast heartbeats. So this accessory pathway, this connection between the top and the bottom of the heart can bypass that and it can be a real problem. This connection can therefore allow a short circuit and this has been described by a group of people called wolf parkinson and white so if you hear the term wolf parkinson white syndrome that's a an accessory pathway giving rise to the possibility of a short circuit i remember years ago i had a patient come in and say oh doc i've got this condition it's i've got a wolf in my heart and i looked at this person thinking what are they talking about Until I eventually twigged that she didn't have a wolf in her heart at all. What she had was wolf Parkinson white syndrome. And that's how she remembered that. Remembered it, which made me laugh. It's quite funny. Anyway, how do we deal with these things? Well, atrial flutter gets treated a bit like atrial fibrillation. We can cardiovert it, but we can use medication sometimes to control it. Occasionally we need to use electrophysiological ablation techniques. to pass wires up into the heart and literally find that short circuit and burn a spot in it to disrupt that circuit, to break that circuit, and we can remove the rhythm by doing that, which is really cool. Atrial flutter can be a bit of a nuisance rhythm, often doesn't respond that well to medication, occasionally it does. So ablations do occur with some frequency for this condition, depending on the patient's requirement and clinical situation. Superventricular tachycardia or paroxysmal superventricular tachycardia with a nodal reentrant short circuit. These people can be seen at a young age. We sometimes see kids, teenagers with this condition. our treatment for it is generally related to how often it's occurring. So if it occurs, say, once every two or three years and it only lasts a couple of minutes, we may not do anything for it because it's really not such a trouble. And if we've diagnosed it and it's not causing too many troubles, then the cure may be worse than the condition. The nice thing is that this paroxysmal supraventricular tachycardia, PSVT, can often be... managed with simple maneuvers people doing what we call valsalva maneuvers or altering the way blood flows back into the chest because if we can alter the way the blood flows back into the chest we can stretch the atrium or contract the atrium and those changes may just knock the person out of rhythm so what i tell people to do is to take a big breath in and hold their breath while they're standing up and blow against their closed mouth and nose increasing the pressure in their thorax by increasing the pressure in their thorax they decrease blood flow back into the chest now imagine this so the blood now flowing back into the chest is reduced now then i say to people release that breath and squat at the same time so as they release the breath the pressure in the chest diminishes Blood flows into the chest and as I squat, the legs compress and squirt blood up into the chest as well. So suddenly you've had a situation where the atria are receiving less blood and then suddenly more blood and not infrequently, manoeuvres like that where we distend or alter the distension of the atria can actually revert that rhythm. We give people a medication in hospital called adenosine, which sort of stops the AV node very quickly and can correct the condition. Some simple tablets can also look after this condition. And if it's really problematic and taking tablets just doesn't work for the individual, these candidates are also really good patients to consider for an electrophysiological ablation as well, because we can put wires up into the area of the heart that's affected and literally... disrupt that short circuit and cure that condition the last type the accessory pathway the wolf parkinson white type well these are a bit complicated and depending on the rhythm that arises will depend on how they're treated my preference tends to be to send these people off fairly early in the course of their presentation to get an assessment for consideration of electrophysiological ablation to remove that accessory pathway, as it can be a little bit of a problem down the line, particularly if these individuals develop atrial fibrillation at a later age. So there you go, a bit of a run through on supraventricular tachycardia. I really hope you've enjoyed it. I hope you've got something from this today. If you have any queries or questions, of course, please let me know. If you've got any suggestions for future podcasts, again, please also let me know. As always, I'd like to wish you the very best. And until next time, please don't die from a heart attack. Goodbye. You have been listening to another podcast from Dr. Warrick. Visit his website at drWarrickbishop.com for the latest news on heart disease. If you love this podcast, feel free to leave us a review.
