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It's always helpful to know what is abnormal by first understanding what is normal. This is why we're going to look more closely at the Normal Sinus Rhythm ECG first, and pay special attention to its findings and measurements. Let's take a look at the rhythm now. Is the rhythm regular or irregular? In this case, it's regular. Next, we look at the rate. What is the rate? This child's rate is 80 beats per minute. And we have to ask ourselves, is that rate normal? Is it fast? Is it too slow? And remember, normal heart rates will vary by age with pediatric patients. A normal heart rate for a 12-year old might be bradycardic for an infant or newborn. So next, we move on to evaluating the P-wave. We ask ourselves, are the P-waves present? We can clearly see in this ECG that the P-waves are present. Do they occur regularly? And we see that each of the P-waves occur regularly. Is there one P-wave for each QRS complex? And we see that there is one P-wave for each QRS complex. Are the P-waves smooth, rounded, and upright? Yes, the P-waves are smooth, rounded, and upright. And do all the P-waves have similar shapes? And the answer to that is yes. Each of them are uniform in shape, and they're smooth and rounded. So now we want to look at the PR Interval for this ECG. Is the PR Interval normal, which means it's less than .20 seconds? And the answer is yes. Because the PR Interval is contained within one large box which equals 0.2 seconds, the PR Interval is normal. Is the PR Interval constant? The answer is yes. So after we answer those questions, we can now move on to the QRS complex of the ECG. Is the QRS interval less than 0.09 seconds? In this case, yes, it is. As long as the QRS fits within two small boxes and is no larger than two and one quarter small boxes, the QRS is within normal range. Is the QRS wide or narrow? And in this case, the QRS is narrow. Are the QRS complexes similar in appearance? We can see that each one looks similar. So now, what is our cardiac interpretation? Well, based on our findings, we can see that we have a regular rhythm with a normal rate. The P-waves look normal with each P-wave following, being followed up by a QRS, rather. And the PR Interval is less than 0.20 seconds. The QRS is less than 0.09 seconds, and with these findings, we can interpret the rhythm to be a normal sinus rhythm. So unless the patient has no pulse or other serious signs or symptoms, there is no significance to this cardiac rhythm.
When talking about treating a patient for something that we consider abnormal, it's always helpful to define and understand what normal looks like, in this case, for a normal sinus rhythm.
In this lesson, we'll look more closely at an example of a normal sinus rhythm on an ECG for a pediatric patient and see what findings and measurements are considered normal, and what to be on the lookout for that would be considered abnormal.
*Normal Sinus Rhythm ECG
The first thing you'll want to look at is the heart rhythm. Does the heart rhythm look regular? Or does it look irregular? In the above graphic, it's regular.
Next, you'll want to look at the heart rate of the patient. What is the patient's heart rate? Is it normal? Or is it too slow or too fast?
Remember, to determine the patient's heart rate you'll want to observe the following areas on the ECG paper printout and perform the following calculations.
The horizontal axis of ECG paper grids is where time is measured. Each small square is 1mm in length and represents .04 seconds. Each larger square is 5mm in length and represents .2 seconds. Therefore a 6 second interval would be 30 large squares.
To determine the heart rate, count the number of QRS complexes over this 6 second interval and multiply by 10.
It's also important to understand that when it comes to pediatric patients, normal heart rates vary based on the age of the patient. For example, a normal heart rate for a 12-year-old will probably be bradycardic for an infant or a newborn.
You may recall seeing some important stats or metrics in the PALS welcome lesson, and the normal ranges for heart rates by age might be worth repeating here.
After looking at the heart rate, check to see if the patient's P-waves look normal by asking yourself the following few questions.
Next, look at the PR interval on the patient's ECG readout and ask yourself the following questions:
The last thing you should look at to determine if the sinus rhythm is normal or not is the QRS complex and ask yourself these questions while you do:
Pro Tip #1: As long as the QRS fits within two small squares on the ECG printout and is not greater than two and one-quarter small squares, it's within the normal range.
So, what is your cardiac interpretation? Based on these questions and on the findings from the ECG readout above, it's safe to say that the patient has a regular sinus rhythm.
Unless the patient has no pulse or other serious signs or symptoms, it's safe to assume that there is nothing of significance, in a negative sense, from this patient's cardiac rhythm.
When it comes to arrhythmias in pediatric patients, consider the following when evaluating the heart rate and rhythm in any seriously ill or injured child:
Children with congenital heart disease may have underlying conduction abnormalities. Interpret the child's heart rate and rhythm by comparing them to the child's baseline heart rate and rhythm. Children with poor baseline cardiac function are more likely to become symptomatic from arrhythmias than children with normal cardiac function.