In last night’s Q&A session, we went over a few NCLEX-style review questions. One question asked about the heart sound S3. Now, I don’t pretend to be perfect know-it-alls who get every question right…and I happened to get this one wrong! We are learning new things all the time, just like any nurse. So I wanted to go back and review the topic a little so we could all learn from that question.
S3 is a heart sound that occurs after the S2 sound. You know the classic “lub-dub” sound of a beating heart? S1 is the “lub,” S2 is the “dub.” So S3 is the sound that comes after that. If you really want to master this material (and you should if you want to be a nurse!) then make sure you find out exactly what is happening in the heart that makes the “lub” and the “dub” sound. A good place to search would be your Health Assessment text, Med-Surg text, or even doing a Google search asking, “What makes the lub dub sound?”
S3 is the sound of the ventricles filling with blood. If you hear it in a child or young adult, it’s usually normal, and referred to as the “physiologic S3.” But if you hear the sound in an adult, it is usually pathological (make sure you know what that word means!). The pathological S3 is also referred to as the “ventricular gallop,” because it kind of sounds like a gallop when paired with the normal S2 sound. Here’s a great website where you can listen to it. Make sure you have your speakers on…
So what causes a ventricular gallop? Well, the sound is caused by a decreased compliance of the ventricles. In plain English, that means that the ventricles are stiffer and less stretchy than they should be. So when the blood gets pushed into the stiff ventricles, it makes a louder noise than if the ventricles were their normal, elastic, self. Stop a second and write down a few possible reasons why the ventricles might be stiffer. Seriously, brainstorm and write it down. You’ll remember this information better if you process it yourself instead of just reading my explanation. I’ll even give you a hint: if a ventricular gallop is pathological, then the reasons it occurred are probably also pathological.
Okay. What did you come up with? If the problem that causes a ventricular gallops is that the ventricles are stiffer, then we are looking for problems in the body that would make the ventricles stiffer. So that would be something like Hypertension, which can lead to arteriosclerosis. And S3 happens to be an early sign of Heart Failure, which also can be caused by hypertension. Those are the most common causes, and therefore would be the most common facts you’d be tested on related to S3.
There are also other causes of S3 besides those related to hypertension and heart failure. Any ideas what they are? Tell me your ideas in the comments section and I’ll give you feedback to let you know if you’re on the right track!