 Hi, welcome to Nursing School Explained and this video on EKG interpretation of atrial rhythms that will specifically discuss supraventricular tachycardia or SVT. If you haven't already done so, I highly recommend also watching my other videos about basic electrophysiology as well as EKG interpretation basics, EKG paper reading as well as determination of heart rate, and then normal intervals and rules to memorize so that you are familiar with how to methodically go about interpreting every rhythm strip. Supraventricular tachycardia basically means that we have an irritable focus above the bifurcation of the bundle of his. If you need to go back and review the conduction system of the heart, this would be a perfect time to do that. And supra meaning above and ventricular the ventricles. So this irritable focus stems from somewhere above the ventricles. This can be the SA node atrial or junctional somewhere from the AB junction. And it always has a rapid ventricular response, which means that the heart rate is usually greater than 150. So here looking at the rules of EKG interpretation and the four steps that we usually go to in supraventricular tachycardia, the rate is usually quite high 150 to 250 beats per minute. In our example here, it's 200 beats per minute. And remember, we do this by counting the number of QRS complexes on a six second rhythm strip and then multiply on it by 10. So if we count here one, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 multiplied by 10 gives us a high rate of 200. So quite fast. The rhythm is regular. We can see that with the naked eye that basically the distance between all these QRS complexes is really evenly. So it's a regular rhythm. The P wave, however, in SVT may or may not be seen and that will always depend on the ventricular rate. Remember that irritable focus sits somewhere above the ventricles supraventricular and therefore comes from somewhere in the atrium or that AB junction. Now the ventricle may or may not respond with a fast heart rate. So the faster the heart rate, the narrower these complexes will be and the harder it will be to see the P wave because it might be buried in a T wave here. So we might have a P wave somewhere, for example, here hidden in this T wave. But if we are able to see them, we can usually determine that we have one P wave for every QRS. And then the intervals, if the P waves are seen, the PRI is usually normal, which means 0.12 to 0.20. And the QRS is usually normal as well. So in this example, we can't really look at the PRI because we can't really determine if there is a clear cut P wave anywhere. But we can certainly look at our QRS's. And as usual, I like to start by looking at them when they start at a bigger line box here. So this would be here. So then one, two for the QRS, which makes the QRS 0.08 and is normal less than 0.12. And therefore, the QRS is normal. And we know that this is a, this rhythm that has to do with the atria above the ventricles in this case. Superventricular tachycardia is pretty common in young and healthy people, but can also occur in patients with coronary artery disease, hypertension, and CHF. Certain dietary supplements are known to induce superventricular tachycardia. So patients who are prone or have underlying cardiac issues should definitely talk to their provider before they take any kind of dietary supplements. Other substances or other causes for SVT are caffeine, alcohol, and illegal drugs such as cocaine and methamphetamines. Signs and symptoms always depend on the rate and duration. Certainly a patient who has a heart rate of 150 probably will have less symptoms than a patient who has a heart rate of 250. They might complain of feeling dizzy or lightheaded. They might have shortness of breath, anxiety. They might have a syncopal event, complaint of palpitations or chest pain or chest pressure. And this can be a very uncomfortable rhythm. And the patients will usually be quite anxious when they present with SVT. Interventions for SVT, we will always have to determine whether the patient is stable and asymptomatic or symptomatic and unstable. If the patient is stable, we can always ask them to perform the vagal maneuver, which means that we will ask the patient to bear down or maybe blow into a straw or if there's no straw available, they can always just kind of blow into their finger. And this maneuver increases the pressure in the thoracic cavity and stimulates the vagus nerve, which is in charge of the parasympathetic nervous system. And we know that the parasympathetic nervous system slows everything down. So sometimes the vagal maneuver works to reset the SA node and convert the patient back from SVT to a normal sinus rhythm. If that does not work, however, we need to go to medication treatment. And that can be adenosine, which is the most commonly used medication in the treatment of supraventricular tachycardia, but it can be given a maximum number of three. So if that doesn't work, the provider might determine that different treatments have to be done or different medications have to be attempted. And they can be calcium channel blockers, beta blockers, the joxin, as well as anti-arrhythmics. If the patient, however, is unstable and symptomatic, meaning that they have a change in level of consciousness or a hypotensive with a systolic blood pressure of less than 90, that means that we have to treat the underlying cause and follow a CLS protocol. And adenosine is included in a CLS protocol. But if that is not working and the patient is now unstable, the patient might need to undergo a synchronized cardio version. If the patient has repeat episodes of SVT and they become unstable and they require frequent hospitalizations for this, the physician might suggest a cardiac ablation, which is basically a cardiac catheterization, where they try to determine where is that irritable focus located above the ventricles that causes this this rythmia frequently, and then they ablate it, they basically just kind of burn that focus away. And then hopefully it is the issue is resolved. Here are some credits and references. Please refer to any of these websites for more rhythm strips. And then here are some other videos from my EKG interpretation playlist. I highly recommend watching these other atrial rhythms, PACs, atrial fibrillation and atrial flutter so that you can compare them to SVT. Thanks for watching Nursing School Explained Peace. Please subscribe to my channel, leave some comments and share this with your friends, and we'll see you soon. Thanks for watching.