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Forum Name: Arrhythmias

Question: What causes low heart rate and how serious is it


 Jeanrich - Tue Dec 08, 2009 12:45 am

My husband had about 3 days where his heart rate was in the 30s and a few times went to the 60s. His diastolic BP was in the 50s and 60s. The systolic varied from 113 to 133. I used a BP monitor to check the heart rate and also checked it manually just to be sure. He had been feeling light headed and dizzy when he would bend over.
His heart rate has been in the 60s now for the last 2 days. What should we be concerned about and what should we do about it?
 John Kenyon, CNA - Mon Dec 14, 2009 12:14 am

User avatar Hello -- There are two totally different things which could cause what you describe as having happened to your husband; one is not very troublesome. The other might be. Both are worth a visit to the doctor's office (preferably a cardiologist) to see which is happening (or if it's something else).

People frequently have premature ventricular contractions (PVCs), heartbeats that are triggered from some location other than the normal sinus node. These can sometimes (especially at slower rates, such as your husband's, which at 60 is really fine) begin to happen as every other beat, alternating with normal sinus beats. Since the happen early they are weak and if you're using a blood pressure cuff with pulse monitor to track his heart rate (as well as blood pressure) what happens in many instances is these every-other-beat-as-PVC rhythms (called bigemeny) will show up effectively halving the actual rate because the premature beats are a litle weaker and the cuff can't feel them. This tends to make it appear the pulse is slowed to 1/2 it's sinus rate. At these times even feeling the pulse at the wrist or carotid artery in the neck may only yield half the palpable beats. There are actually the correct number, but you can only feel the sinus ones. This can cause lightheadedness if it is sustained for a long period of time.

By the same toke some people sometimes develop what's called a 2:1 heart block, usually in the atrioventricular (AV) node, a nerve center in the middle of the heart that helps convey the sinus beats from the upper chambers to the lower ones. If the AV node becomes diseased it can begin to show intermittent 2:1 blocking, in which every other beat is essentially blocked from reaching the ventricles. The result is more often lightheadedness because the effective rate truly is cut in half. It's impossible to tell which is happening without an EKG or perhaps a portable Holter monitor to record these events. While ventricular bigemeny (the alternating premature beats) can cause symptoms and sometimes requires treatment (medication), it's usually not too much of a concern. An AV block is another story and may or may not require treatment or even possibly insertion of a pacemaker to make sure the heart beats at an appropriate rate.

It would be very important for your husband to have this evaluated to see what's going on. I suspect it to be bigemeny (the less serious problem) because the blood pressure seems to hold up well during these episodes, whereas it usually would drop more during periods of block, but there's only one way to be sure and to have the correct treatment (or just advice), and that's to have it looked at by a cardiologist. I would strongly recommend this be done promptly to avoid problems.

Good luck to you both. Please follow up with us here as needed.
 Jeanrich - Tue Dec 15, 2009 2:21 pm

Thank you very much for your reply. We didn't get to a cardiologist, but our family Dr. did do an exam, and EKG and the Holter monitor. We're waiting for the results of that.
I really appreciate having such a forum to consult. I've done it on other issues and it has always been right on.
Thanks again
 Jeanrich - Thu Dec 31, 2009 12:52 am

Here is the results of 24 hrs on Holter monitor your input please............

Monitoring started at 2:45 PM and continued for 26hr 22 min. The rhythm was sinus. The average heart rate was 74BPM. The minimum heart rate was 42BPM occurring at 8:20:38 AM. The patient's rhythm included 1hr *min of bradycardia. The slowest single episode of bradycardia occurred at 8:20:11AM D1, lasting 1min 25 sec with rate of 42BPM. The maximum heart rate was 117 BPM, occurring at 6:30:02PM. The fastest single episode of tachycardia occurred at 6:29:56PM D!, lasting 26 sec with rate of 117 BPM. The longest R-R interval was 1.6 seconds occurring at 4:34:44 AM D1. The longest N-N interval was 1.6 seconds occurring at 6:17:25 AM D1.

Ventricular ectopic activity consisted of 4719 beats, of which,21 were triplets, 102 were in couplets, 877 were single PVCs, 3065 were interpolated PVCs, 3 were in R on T, 49 were single VEs, 497 were bigeminy, 105 were trigeminy.

Supraventricular ectopic activity consisted of 15 beats, of which, 3 were in 1 run, 12 were single PACs. The supraventricular run occurred at 2:21;05 pm D1, consisting of 3 beats with maximum heart rate of 95 BPM.
 John Kenyon, CNA - Fri Jan 01, 2010 11:10 pm

User avatar First of all you're very welcome and thanks for the kind words about the site. It's why we're here and we do our best.

As for the Holter monitor findings, this is not of terribly great concern, but should be evaluated properly by a cardiologist when practical. It sounds as though everything I suggested plus a few other things have been going on, all of which, in the absence of proven heart disease, would be suggestive of nothing except perhaps a very irritable heart muscle. This could be due to anything from a natural propensity to too much caffeine to perhaps some minor structural abnormality. There was no mention of prolonged Q-T interval and nothing else to suggest a seriously worrisome problem. There were a lot of PVCs, which is not at all unusual in a given individual, and oddly enough the majority (a good 3/4) were interpolated PVCs, which means simply they occurred directly between two regular sinus beats without displacing one of them. This can effectively double the heart rate while it's happening, which could make it difficult to tell the difference between an actual rate increase and a perceived one. The lowest rate was above 40, early in the morning, and the fastest, 117, would barely be considered rapid. Both are within the range normally seen in many normal, healthy people. There were a number of triplets and couplets, which is worth a second look by a cardiologist, but not truly noteworthy. The rest all falls within what one might see in a random sampling of healthy people.

Since this exam was ordered by a GP I think it deserves the attention of an actual cardiologist -- and now the work's been done so it shouldn't be too much to ask for one to just look at the result. While I doubt there is anything else remarkble to be seen that wouldn't have been noted in the report, it would be prudent to have this done and possibly followed up with an echocardiogram to determine if there might be a prolapse of the mitral valve leafets (not serious but something worth knowing) or any other structural abnormality. If there is nothing else found, this can then be considered "normal" for your husband. The main reason for the followup would be to determine if any of this might suggest a cause of lightheadedness, with special attention paid to the Q-T interval. If that's normal then there's probably nothing further needs to be done.

Good luck to you both again, and please do keep us updated.
 Jeanrich - Wed Feb 17, 2010 6:18 pm

I can finally say that everything is ok. He had a stress test with 2 nuclear scans, an echocardiogram and an electrocardiogram. There is no blockage but did have PVCs. His blood pressure is good, too. The rate does drop once in a while but not way down. He is to be checked again in 6 months.
Thank you again. This is a great site.

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