03.03 Sinus Tachycardia

Hey guys, in this lesson we are going to talk about the characteristics of sinus tachycardia and most common symptoms, some of the possible causes, treatments and nursing interventions, and we are also going to break down each of the steps to learn how to identify it on an EKG.

So in sinus tachycardia the SA node initiates the electrical conduction just like in normal sinus rhythm. The only difference is that is beating at a rate greater than 100 beats per minute. The SA node still initiates the impulse it’s called sinus tachycardia.
So let’s use the 6 step method to look at the characteristics and identity the rhythm on an EKG, and if you haven’t seen the normal sinus rhythm lesson make sure that you watch it because cause that breaks down the 6 steps in more detail and it will help you with abnormal rhythms. So let’s start with number one and find out our rhythm is it or irregular, so let’s count the small boxes between this R wave and this R wave and we have about 13, we have 13 from here to here also and here to here we have 13 boxes. So it’s consistent and our rhythm is a regular rhythm. In step number 2 we need to look at the heart rate, we determined we have a six second strip because we have 30 boxes, so we count the R waves and we have 11 so we multiply by 10 and get 110 beats per minute. Let’s also do the 1500 method as well, 1500 divided by 13 and we get 115 beats per minute again it’s more accurate. So our heart rate is from 110-115 beats per minute. In step 3 let’s look at the P:QRS ratio, do we have one P wave followed by one QRS, and we do. Every P wave has a QRS behind it. We have a 1 to 1 ratio. In step 4 let’s look at the PR interval, from beginning of P to beginning of Q we have 5 boxes and it 0.20 seconds which is normal range. Step 5 would be our QRS complex, from beginning of Q wave to S wave is 2 boxes which is 0.08 seconds which is also with in the normal parameters. So step 6 we identify our rhythm as sinus tachycardia. Let’s recap the characteristics. So we have a regular rhythm, a heart rate is 110-115 beats per minute, our P to QRS ratio is one to one our PR interval is normal and our QRS complex is normal. Our rhythm is Sinus tachycardia. Because it is an abnormal rhythm it is our job as nurse to find out what is going on with our patients that is causing them to be tachycardic.

So when you have a patient with sinus tachycardia the first you need to do is assess them, find out their signs and symptoms are they are stable or unstable. Sometimes patients who are stable and tachycardic have some signs and symptoms. If they are unstable, they will report a rapid heart rate, palpitations and lightheadedness due to a decreased cardiac output which will cause shortness of breath, chest pain and hypotension. The heart sends blood to the brain, lungs, body and heart itself, so when the heart is contracting too fast it does not have enough time to fill up with blood. The stroke volume is decreased, stroke volume is the amount of blood ejected with each contraction which is about 75 ml, when the heart does not have enough time to full up with blood the stroke volume is decreased to about 50 ml and decrease cardiac output. This causes shortness of breath, chest pain, hypotension and lightheadedness. Then you need to determine the causes, find out why so it’s easier to treat. These are some of the most common causes, fever increases metabolic demands which causes tachycardia, dehydration hypotension and anemia decrease the blood volume in the circulatory system, so the heart thinks it needs to compensate so it speeds up to increase cardiac output. Anxiety and fear increase tachycardia because of fight or flight. Pain increases vital signs and causes tachycardia, if you ever have a patient who complains of 10/10 pain and a heart rate in the 120s, make sure you treat the pain first, once pain is treated the heart rate will go down. Let’s talk about treatments.

So let’s talk about what to do for our tachycardic patients, first thing we will do is determine the cause if you can find out why it’s easier to treat them. Next, we need to find out if they are stable or unstable. If they are stable, great continue to monitor them. If they become unstable or their heart rate increases to the 120’s - 130s have the patient perform a vagal maneuver bear down so it can stimulate the vagus nerve and decrease the heart rate. If that does not work, then we usually administer a beta blocker or a calcium channel blocker. According to the ACLS guidelines we need to do Adenosine, first do 6mg of Adenosine it will slow down heart rate tremendously or stop it completely. When it picks back up again at a normal rate of 60-100. If the dose needs to be repeated, we can administer 12mg of Adenosine. If this does not work and the patient is unstable then they need a synchronized cardioversion. Let’s talk about synchronized cardioversion, If I have a patient with a heart rate 140s and unstable and symptomatic, we will apply dfib pads and connect to the defibrillator. The monitor needs to show synch mode so it will synchronize with the R waves, it will deliver the shock after the patient has repolarized to prevent v-fib. We will talk about v-fib in another lesson.


So the main key points to take away from this lesson are the characteristics of sinus tachycardia are the same as normal sinus rhythm, the only abnormality is the heart rate is greater than 100 beats per minute. Always assess your patient first, are they stable or unstable. Determine the cause if you know why they are tachycardic it is so much easier to treat them and you know how to treat them. Always follow the ACLS guidelines with 6mg of Adenosine or 12mg for the second dose, if they are unstable do a synchronized cardioversion.

I hope you guys have enjoyed this lesson and feel more comfortable being able to identify sinus tachycardia on an EKG and that you know what nursing interventions to implement when you see this rhythm. Make sure you check out all the resources attached to this lesson so you can keep practicing and becoming more familiar with sinus tachycardia. Now, go out and be your best self today! And, as always, happy nursing!