Sinus Rhythm (Nursing)

00:01 Hi, welcome to our electrocardiogram video series.

00:05 In this one, we're going to talk about sinus rhythm.

00:09 So far, we've covered the components of the ECG paper and broken down the cardiac cycle to see how each phase is reflected as a wave.

00:17 We also went through the seven basic steps to analyzing any ECG strip.

00:22 Now we're going to put that to the test.

00:25 ECGs come in many different forms depending on the health of each patient.

00:30 By the end of this course, you'll be able to identify most of them.

00:34 However, before you start diving into the world of pathology, you have to have a good grasp on the basics.

00:41 You can't recognize sick if you don't know what healthy looks like first.

00:46 So let's take a look at a normal sinus rhythm ECG strip.

00:51 Let's take another look at our beating heart here and do a brief recap on the waves and intervals of an ECG strip.

00:59 Remember, the electrical impulse travels from the atria to the ventricles and its pathway an influence on the heart muscle is what's reflected on the ECG strip.

01:09 Now the impulse originates in the sinus or the sinoatrial or here's a third name, the SA node - they all mean the same.

01:18 It travels from the SA node through the left and right atria, causing their contraction which is reflected in the ECG as the p wave.

01:29 The impulse then heads through to the AV node, but it doesn't just pass through.

01:35 It gets delayed or slowed down.

01:37 This delay is documented in the ECG strip as the PR segment.

01:43 Next, we have the QRS complex, which represents ventricular contraction.

01:49 This contraction is caused by the impulse entering the ventricles and dispersing through the Purkinje fibers.

01:56 The next wave is the T wave, which is caused by the repolarization or relaxation of the ventricles.

02:03 This period of time or interval between ventricular depolarization and repolarization, is represented as the ST segment in an ECG.

02:13 Finally, we have the U wave, which actually may or may not be present on the ECG strip.

02:20 Although we don't exactly know what causes it, it's believed to be the result of a delayed repolarization of the Purkinje fibers.

02:27 So let's do a quick review of how to analyze any strip.

02:32 Step one, you will analyze the heart rate and rhythm.

02:38 Remember, you're making sure that you have the same equal distance between the R waves of the QRS, and the p waves.

02:46 So they should plot along equally, p wave to p wave to p wave, r wave to r wave to r wave.

02:54 The next step is to analyze the P waves.

02:57 You should have one P wave for every QRS.

03:00 They should all look the same and they should measure out equally.

03:06 Third step is to measure the PR interval.

03:09 You measure from right where that P wave starts to leave the isoelectric line down to where it starts to dip down again, that is the PR interval.

03:20 Now, step four is measure the QRS duration.

03:24 So you're going to measure how wide the QRS is.

03:28 Step five, take a look at the ST segment.

03:31 Step six. Look at the T wave, we want to make sure that isn't depressed or elevated.

03:37 And then step seven, we're going to measure the QT interval.

03:42 Now a normal P wave is the atrial contraction precedes every QRS complex in a normal sinus rhythm.

03:50 The rhythm is regular, but can vary slightly during respirations, and that is completely normal.

03:59 The rate ranges between 60 and 100.

04:03 Anything below 60 is sinus brady.

04:06 Anything above 100 is sinus tachycardia.

04:10 Now the P wave is positive in I and II.

04:15 Now it's little biphasic in lead V1.

04:19 But remember, there's a potential of a patient is having problems, we want to really good detailed look at the electrical activity in the heart, we'll use a 12-lead.

04:29 So those are just referring to different types of leads.

04:33 If a patient is in the hospital, they're most likely just on 5-leads for regular monitoring.

04:38 But if we do a 12-lead ECG, that's when we suspect there might be a bigger problem.

04:45 So when we say the P wave is positive, that means it's up above that isoelectric line It is positive in lead I, lead II and biphasic in lead V1.

05:00 So let's do it, let's dive in and hit the seven steps with this ECG strip.

05:07 So first, let's assess the heart rate and rhythm.

05:11 Now if you count these up, we have a rate of 80.

05:15 Normal sinus rhythm is between 60 and 100, so we're spot on.

05:20 Look at the rhythm. Is it regular? Well, measuring the distance between the QRS complexes, yeah, it plots right along, it's regular.

05:30 And you measure between the P waves.

05:34 Yeah, it's regular.

05:36 This is what we would expect to see in a sinus rhythm.

05:39 So let me show you right where we looked here.

05:42 We're going to analyze the P waves in step two.

05:46 So see those blue boxes that have appeared? That's to remind you of what the P waves are.

05:52 Now look, there is one P wave is present for each of the QRSs, and they all look the same.

05:59 They don't just want to glance at that.

06:00 You really want to be disciplined to look at each P wave, make sure that it's there for every QRS.

06:08 Right, and then step back, and make sure those P waves all look similar.

06:14 Step three, measure the PR interval.

06:17 Now take a look at the strip we've provided.

06:20 You're going to measure from where the P wave starts to the R wave.

06:25 Now I'm going to pause and let you try and measure that.

06:28 And then we'll show you the answer on the screen for this particular strip.

06:35 Step four. Now we're going to measure the QRS duration.

06:40 Now we have it marked for you here.

06:42 You want to measure it when that Q wave dips down below that isoelectric line up to the R and to the S.

06:50 What we're looking for is a normal value, so that's less than 0.12 seconds or 3 small squares.

07:00 Remember, each tiny square is worth .04 seconds, so 3 x .04 would be .12.

07:09 And that's the number you're looking for, a QRS that is less than .12.

07:17 Step five is to look at the ST segment.

07:20 You want to make sure there's no depression or elevation.

07:24 Remember, we're comparing that to the isoelectric line.

07:28 Step six, examine the T wave.

07:31 Make sure that it's rounded and not peaked or tall.

07:35 Now the seventh step we talked about, we're looking for QT elongation.

07:40 Remember, greater than 50, we're in really big trouble.

07:44 Normal is less than 0.46 in women, and less than 0.45 seconds in men.

07:51 So you've done it all seven steps.

07:55 You've walked through this strip to analyze what it looks like to have a normal sinus rhythm strip.

08:03 Now QT interval extends from the beginning of the QRS complex through the ST segment and to the end of the T wave.

08:11 And within the cardiac cycle, it represents the entire process of ventricular depolarization and repolarization.

08:20 So let's review why this is normal sinus rhythm.

08:23 The heart rate is between 60 and 100.

08:26 The rhythm is regular.

08:29 There's a P wave before every QRS and they look the same.

08:33 The PR interval falls between 0.12 to .20, and the QRS is less than 0.12 seconds.