Normal Heart Sounds w/Pacemaker?

ChaseZ · Jul 22, 2013

Pacemakers themselves do not create abnormal heart sounds. What you most likely heard was a valve murmur in a patient who happened to also have a pacemaker. The majority of patients who get pacemakers have significant cardiac disease which causes various clicks, murmurs, and extra sounds. A pacemaker, specifically a Bi-Ventricular, may actually "fix" extra hear sounds. But in a patient who has a pacemaker and a structurally normal heart you should hear normal heart sounds. An example would be a person who got the pacemaker for a 3rd degree heart block.

The only new heart sounds that would worry me would be a friction rub or muffled tones. But that is mostly for new pacemakers and if they did perforate something during the procedure they would likely be crashing and you would have more than heart tones to go on.

With pacemaker it is always nice to know what kind of pacemaker it is and what mode it is in. Not everyone with a pacemaker 100% paces.

Cinquefoil · Jul 24, 2013

Thank you, ChaseZ. I appreciate your reply.

On the day, I deprioritized digging in the patient's chart to see if the heart sounds were known... because I kept hearing my former RN instructor say, "When the patient has an abnormal rhythm/sound....Look at the patient!" The patient looked reasonably good. And clearly the MD is aware they have cardiac Hx! And they have a pacemaker, so what can happen? And I had patients in acute pain taking hourly IV meds, discharges, admits. But after the shift I was had second thoughts, and some new-nurse self-doubt and shame. This is the C in CAB after all.

Doing things over again, I would prioritize checking the patient's Hx more and communicate non-urgently but in a more timely way to the MD about any heart sounds I heard that were not justified by the Hx. Not out of urgent concern as much as out of double-checking and showing that I was paying attention. Because also... would a pacemaker help, or stop being as helpful, if the valve issues get worse?

Thank you again, and any more thoughts out there?

Editorial Team / Admin · Jul 26, 2013

I explain to our cardiac patients:

Ya got yer plumbing and ya got yer electrical.

Valve issues = plumbing

Coronary artery lesions/disease = plumbing

Bradycardia and dysrhythmias requiring pacemaker = electrical

Now, chamber enlargement/hyperplasia can be caused by long-term hypertension, MI damage, post-MI remodeling or long-term "leaky"/incompetent valve (to name a few possibilities).

When the heart chambers are enlarged, the electrical pathways may become distorted as well.

What are the indications for pacemaker placement? Try here: Indications and Recommendations for Pacemaker Therapy - American Family Physician

To address your question:

If valve issues (plumbing) worsen in a patient with a pacemaker (electrical), the presence of the pacemaker (why it was placed) remains, and it's probably still a good thing the pt has the pacer.

The pacer is placed for electrical issues, not to "fix" an incompetent valve (plumbing).

Hope I understood the question, am trying to make it simple to understand. :)

Editorial Team / Admin · Jul 26, 2013

Heart sounds occur from the flow of blood through the heart, and turbulence created with the closing of the valves (plumbing!).

There are lots of cool online sites with examples of different heart sounds.

Electrical stuff is pretty quiet, as a rule. :)

Cinquefoil · Jul 28, 2013

I guess the question is, when would you get worried that the plumbing was changing too fast for the electrical compensation (pacemaker) to keep pace?

This being a different question from the ethics of a very elderly patient w/dementia undergoing all the interventions that being worried medically might involve...

I'm asking just out of curiosity....this line of questioning may be a red herring in that there are probably about a dozen other more useful questions I could ask about cardiac nursing, but for some reason this one is really interesting to me, so bear with me a moment.

Or is this a silly question because, if having a pacemaker doesn't help, it's VAD, transplant, or a permanent position pushing up the daisies??

nurseprnRN, BSN, RN · Jul 28, 2013

The plumbing isn't going to change whether there's a pacer driving the conduction system or not.

Let's go back to the beginning.

You've got the SA node that normally sends out an impulse that makes the atria contract in a nice organized fashion, wringing blood through the mitral valve (in the left heart) and the tricuspid valve (in the right heart).

Then the impulse gathers together at the AV node and goes down the conduction system in the ventricles to make them contract in a nice organized fashion to wring the blood out the aortic valve (left) and pulmonic valve (right). Pacemakers have sensors in them in the atria and the ventricles, and the little things think like this:

Atrial circuit: "OK, do I see an atrial impulse in the specified frequency? Yes? Great, I do nothing, but I do tell the ventricular circuit. No? OK! Must be a problem with the SA node! I will stimulate the atria! I tell the ventricular circuit I have done this! OK! My work is done until it's been too long since the last atrial contraction, so then I do it again!"

Ventricular circuit: "Do I see an impulse coming down from the AV node to the ventricles? Yes? OK, I do nothing. No? Well, did the atrial circuit sense one or send one? Yes? OMG, must be an AV block! Then I must send one through the ventricles at a specified interval after that happened."

This results in normal hemodynamics, which results in valve sounds.

It's helpful if you can step back first and think of what the anatomy of the circulatory system is supposed to accomplish. It's supposed to move a fluid around in a bunch of blood vessels, pumped out at high pressure from the left side of the heart, returned to the heart by passive squeezing in the veins and kept from sloshing backwards by valves in the vessels. Then the right side of the heart is supposed to push it through the lungs (at a lower pressure, because it only has to perfuse the lungs right next door, not all the way down to the toes like the arterial system) to do the gas-exchange thing. Then the fluid goes back to the left side of the heart and out to the body again.

Let's look at the blood flow in a linear fashion. I regret that I cannot give these in color so you can see the blue of venous, the red of arterial. But hey. Draw them on a piece of paper in color. The lungs are pink :)

Body > Veins > Vena Cava > Right Atrium > tricuspid valve > Right Ventricle > pulmonic valve > Pulmonary Artery > LUNGS >Pulmonary Vein > Left Atrium > mitral valve > Left ventricle > aortic valve > Arteries > Body

If you think about what's going on at each valve in systole and diastole AND you remember to listen in the right place for each valve, you can figure out whether you have a systolic or diastolic murmur and which valve it's coming from.

Draw a picture of the 4 chambers of the heart. Include the mitral valve between the a & v on the left side, and the aortic valve at the outflow to the ventricle into the aorta.

What goes on at the mitral valve? In diastole, it's wide open, so blood can go from the atrium to the ventricle (a quiet thing). In systole, it slams shut (the S1). You hear the mitral valve best at.... the apex, right. SO... if you have a mitral stenosis, things'll be noisiest there in diastole, because the blood will be going thru a too-small hole into the ventricle. If you have a mitral regurgitation, there’ll be a blurry noise there at systole, as blood goes backwards through it when it should be slamming shut. Think about this and don't go on until it is clear to you.

What goes on at the aortic valve? In systole, it's open so blood can get out to the aorta (quiet). In diastole it's slammin' the door, so blood can't go backwards (that’s the S2). So if you have a stenosis there, when and where do you hear the blurry noise? Right, in systole, and just downstream of the valve in the arch, as the ventricle tries to force blood thru a tight (stenotic) opening. OK, so if you have a regurgitation there, when do you hear it? Bingo, in diastole, because the partly-ajar valve is unable to slam shut and blood comes backwards thru it, making a racket.

Now, you will notice that these things happen whether or not the rate is regular; if there is a P wave, there is blood being pumped efficiently (more or less) into the ventricle. Even if there isn't a P wave (atrial fib), you will notice that the two heart sounds S1 and S2 are dependent on the ventricles doing their thing, no matter how regularly. If they aren't, then your patient is dead and has no heart sounds, or else he is in VF and there's too much racket with CPR and defibrillating going on to hear anything, not that anyone would be listening to heart sounds with all that going on anyway. :)

So, back to your pacemaker question. Since an artificial pacer is designed to drive the electric system, this results in atrial contractions and ventricular contractions, with luck in a nice synchrony to duplicate normal conduction. Since the heart sounds are valvular, driven by blood flow, the only influence the pacer impulses have is to be sure there is some flow, and that's what makes the heart sounds. :)

S3 and S4 are made by the blood banging around inside the ventricle itself, turbulence in there, NOT having anything to do with the S1/S2 valvular sounds. They have to do with the general health (flabby? stiff) of the ventricular wall itself, an indication of the condition of the muscle (failing? too thick? dead spots? coronary artery disease? aneurysm? contusion? organ rejection post transplant?) and this will not be influenced by a pacer either. Alas, a pacer will not head off or change the need for a VAD or transplant if the basic protoplasm is crappy for any of the above reasons, including progression of any of the above reasons. All it does is turn on the electricity. If the lights don't come on, you need to get a flashlight or change the bulbs. :)

I hope this helps you put it all together. Ask again if not.