Sinus rhythm vs pacing

Hi. I am a new member, just got my first PM, and this is my first post.

I've had probably 20 syncope episodes over the last dozen years. Some are Vaso Vagal but others were caused by my heart stopping (which we finally figured out 3 weeks ago and caught on a heart monitor as it was happening). I have bradycardia, with a resting heart rate around 50, and my BP is usually around 100/60. Luckily, heart and arteries are in good shape structurally, but there apparently was a disconnect between my brain and my heart, so sometimes my heart didn't get any signals to beat. No apparent issues so far. They installed a Sorin REPLY DR without defibrillator.

I'm a bit confused about how the PM coordinates signals with one's natural sinus rhythm. My PM is programmed for a minimum resting HR of 60 bpm. If my resting heart rate drops to 50, the PM brings it up to 60. I'm new to this, so please forgive me if this is a stupid question, but how does the PM manage to synchronize with the body's normal sinus rhythm?

For example, if my HR is 50, my heart would beat naturally every 1.2 seconds. I am guessing the PM would fire after 1 second. Would the fact that the PM fires take over control prevent my natural sinus rhythm from firing again in another 0.2 seconds? I'm not sure if I am making this clear. I'm just wondering how the Apm works together with my normal sinus rhythm so I have a nice, even 60 bpm resting heart rate.

Thanks for any answers or links that help me understand. I still have a lot to learn.

Lou

11 Comments

Electrical system of the heart

by golden_snitch - 2013-09-14 01:09:29

Hi!

Don has already explained this well, so nothing to add.

I would just like to add: There is no connection between the brain and the heart regarding the electrical signals that travel through the heart. The heart has an autonomic electrical system. Never seen that experiment with a frog's heart that's taken out? It continues to beat. A sick heart that's being taken out because of a heart transplant can also continue to beat for a short while. Now, this is different from our lungs for which there is a certain area in the brain that provides the signals when to breath in and out. But the heart is autonomic, there is no center in the brain that tells it how fast or slow it should beat.

By the way, I have a Sorin Reply, too. You got a really nice piece of machinery there, just perfect for someone with sinus bradycardia :)

Best wishes

Inga

Thanks!!

by lbdina - 2013-09-14 01:09:35

Thanks for the quick responses and the great info. I will also check out the resources supplied.

So, I gather that when the SA node fires, those cells are smart enough to "Reset", whether the last electrical signal was generated by the body or from the PM. Then, this signal by signal cycle repeats indefinitely (we hope!). If my understanding above is correct, that answers my question. Thanks.

Yes, these PMs are sophisticated little buggers. I want to understand mine well in time.

Thanks again...much appreciated.

Lou

Good animations

by lbdina - 2013-09-14 02:09:21

Tracey,

Thanks for the site with the video animations. Excellent!!

This is a great,support website...thanks again folks.

Lou

Wow!!!

by Moner - 2013-09-14 02:09:31

Hi Dina,

You couldn't have gotten better information from these 3 "cCacker Jacks" of the pacemaker club. I consider them the resident experts.

Stick around, you'll learn a lot from this wonderful website.

By the way, I had my pacemaker put in on January 2012, exactly for the same reason you did. I have vasovagal syncope or CNS, ONLY, when I come down with the stomach virus.

I go into a "sinus arrest" lasting around 20 seconds.

I'm just curious, what happens to you, when you get a stomach virus, I hope you DON'T have the same reaction, like I do.

Welcome!!


Moner

>^..^<

Good Info

by Casper - 2013-09-14 03:09:08

Don gave some good info here, after the QRS wave there comes the "T" wave, before it begins the normal cycle again.

I know this because I just had a "EKG" and was told I had "inverted" T waves, I was very surprised, because I've had numberous "EKG" reports in my life, but never been told this.

Welcome to the club Lou!!!

Wow-2!

by lbdina - 2013-09-14 04:09:37

Thanks again, all.

Moner....

I am not sure if I have every experienced Vaso Vagal syncope associated with a stomach virus or flu, but I may have. I've had about half a dozen Vaso Vagal syncopes after injuring myself (sprain, cutting myself, hitting an elbow hard on concrete, that sort of thing).

What scared me most were nighttime episodes. I'd be sleeping soundly, then all of a sudden I'd awake in a panic feeling terribly ill. I'd feel extremely nauseous, dizzy, buzzing ears, disoriented, drenching sweat, changes in vision, and I'd finally pass out. I used to thing these were Vaso Vagal episodes too, but my cardiologist told me most of these night episodes were cause by my heart slowing dramatically or stopping completely.

About a month ago, I passed out while on a tall extension ladder. I don't remember falling, but my wife said I landed flat on my back. That was probably a Vaso Vagal episode because I really slammed my elbow again the brick front of the house, it was hot, humid and I hadn't eaten anything. That landed me in the hospital for 6 days. The first night, I passed out in the bathroom and cracked my head on the tile floor (no head damage, but the floor will never be the same!!). I was wearing a heart monitor at the time I passed out and it recorded a 12 second pause. I woke up just before they were ready to commence CPR. I have had a lot of these episodes, but this is the first we ever caught red-handed. I don't know how long the other pauses were.

Hope that fills in the blanks.

Lou

Thanks, Inga

by lbdina - 2013-09-14 05:09:25

Inga,

Thanks for clearing up my confusion regarding the heart's autonomous electrical signals. I'm learning a lot quickly from this great forum and all the helpful folks.

Glad to hear you like your Sorin Reply, and also to hear it is the right piece of equipment for my Bradycardia and Sick Sinus Syndrome. I'm not sure if it will help with my legitimate Vaso Vagal episodes or not, but I would think it might help a little. At least my heart rate,won't be dropping along with my BP and dilation of my blood vessels.

They programmed it for a resting HR of 60, a "normal" ambulatory rate of 70, and when it detects a rapid drop in my HR, I think it is set to 80 bpm. I have had only my first initial visit after implantation, and the limited stored data looked okay. I have a 2nd visit in another 7 weeks, and they may tweak the program at that time based on the larger data sample and how I am feeling and reacting.

It's a bit tough to assess how I am doing in isolation, since I am recuperating from a nasty fall, bruised back, lots of medications, etc. I am very hopeful the Sorin Reply will end my nighttime meltdowns, and reduce/eliminate my Vaso Vagal episodes. Thanks for your valuable input.

Lou

Hi Lou (again)

by Moner - 2013-09-14 11:09:46

Hi again,

With all the other episodes you have to contend with, I hope you don't pass out when your sick.

I can't beleive you feel off a ladder, that must have been very scary. You really could have harmed yourself.

The vagus nerve is an amazing cranial nerve, it controls a lot of bodily fucntions (breathing, eating, regulating the heartbeats), I'm glad you didn't have to get CPR. It sounds like you had a sinus arrest too!

Hope you're sleeping better too!

Moner

>^..^<

Be prepared fpr a flurry of msgs!

by donr - 2013-09-14 12:09:45

The PM is a magnificent little digital computer that can use logic algorithms to solve electrical heart problems.

There is NO sine wave master clock that sends out a continuous wave to synchronize things. The master timer is the SINUS NODE "SA". It is really a counter that times things. It really controls the Atria of the heart - the top two chambers. It generates a small pulse called the "P Wave" on your ECG. That triggers the Atria to contract. That electrical signal travels down a bunch of tissue to the Atrial-Ventricular Node "AV" that controls the ventricles , the lower two chambers. On the way to the AV node, it is delayed a bit to allow the ventricles to flll w/ blood from the Atria. The contraction of the ventricles is seen in your ECG by te BIG complex called the "QRS Wave." After they complete their contraction, the tissues have to reset themselves electrically to prepare for the next cycle. All this works by timing in the cells.

So - what does your PM do? It has a very precise & accurate clock; it also has a memory that is chock full of stored parameters for your heart's beating timing. The PM can also sense when things happen & make decisions in accordance w/ the algorithms. First, it looks for a P wave in your heart beat & starts a timer counting. The memory has a stored time for when the Pm will send a signal to the AV Node IF the QRS wave is not sensed. Naturally, ithe stored time is a bit longer than your heart's natural time. This allows the ventricles to beat on their own if 6the signal gets there a bit late. No QRS sensed, the PM generates a signal & sends it to the AV to trigger the ventricles to contract. Meanwhile, the PM has been keeping track of the time since the last P wave. It has a stored time for when the next P wave is expected & if none is sensed, the PM sends a signal to make the Atria contract.

The PM also has algorithms to account for many other functions - f'rinstance, it can adapt to your level of efort & the changing times required as your heart beats faster under load.

Now - FORGET Heart Rates - NO such thing. There are TIMES for the average beat. Each & every beat is individually timed. Therefore, if an individual beat is late in something happening, the PM takes over immediately & makes sure that beat occurs. It does NOT wait till the next beat to function. If your lower rate is set at 60 BPM, , the PM expects a P wave to occur every 1.0 seconds. It looks for it in its sensing. If the beat is late, the PM will fire after 1.1 seconds to replace the late beat. That .1 second delay is variable & controlled by the PM's stored data. It has stored data for tyher time to wait for the AV node to fire the ventricles, also.

Remember - the PM works on a beat by beat timing system. It has NO idea what the BPM number is. It uses an elapsed time for each function & applies it to EVERY beat.

Don

pacing

by Tracey_E - 2013-09-14 12:09:54

I don't understand how the sinus node knows to wait another second before the next beat, but it usually works out that way! If it did try to beat immediately after a paced beat, a little half beat is called a PAC (premature atrial contraction), they're harmless and often we don't even feel them. Or it's possible the next full beat would be a little sooner and your hr would be a little higher than 50. Hopefully someone else can explain it better than that!

St Judes has some great animations that explain it all
http://health.sjm.com/arrhythmia-answers/videos-and-animations

Just love that Vagus Nerve!

by lbdina - 2013-09-15 05:09:38

Moner,

Yes, ladder diving is a sport I am inclined to discourage! It wasn't scary falling off the ladder because I passed out cold before I fell. Perhaps there was sinus arrest, but I definitely had a vaso vagal episode. I hadn't eaten breakfast, was standing on a ladder for a long time, hot, sweating in the sun, tired, working hard, then whacked my elbow hard against a brick wall. It hurt like hell and was the final straw that triggered the dwindling spiral.

My wife said I landed flat on my back (fell about 10 feet) and was unconscious for about 60 seconds. When I came to, I was able to move arms and legs, but not my torso. I thought I broke my back, and after 20 minutes trying to see if I could move, the paramedics took me to the hospital in a neck brace, strapped to a back board. Miraculously, no broken or fractured vertebrae, no bulging disks, etc. After 8 hours in the ER, they were going to release me, but I came close to passing out again when I tried to sit up. That's when they admitted me to the hospital. An hour later, I blacked out in the bathroom, whacked my head on the floor, and woke up to a team of doctors and nurses ready to give me CPR. My heart stopped 12 seconds.

Got my pacemaker 4 days later, and left the hospital the day after that. It's a bit difficult to assess how the pacemaker is doing due to my back injury. I was on powerful opiates for 3 weeks for pain and was unable to walk for almost 2 weeks. Came off the drugs 5-1/2 days ago and have had some withdrawal symptoms ever since, including insomnia, jumpy restless legs, edginess, some sweating and occasional, mild nausea, plus stiffness and soreness from the injury. I haven't had a good night sleep in 5 days and have been very tired. So, I can't really assess my pacemaker implant in isolation at this point.

I still have light headedness, get a little dizzy, feel a little nausea and mild sweating. If I am vertical for a long period of time, I can feel it. I suspect I have orthostatic hypotension, and possibly an electrolyte imbalance. I definitely have vaso vagal and low BP (usually around 100/60 or a tad higher). Like I said, the trauma of my fall, a 6 days hospital stay, drugs, recovery, etc, makes it a bit more difficult to connect the dots.

I've had a few weird sensations in my chest when relaxing in my recliner. It feels like when you have a muscle or nerve jumping in your arm or leg, but not as strong, and I timed it at about 4 second intervals. It goes away after awhile, but I don't remember ever feeling this before getting a pacemaker. That has happened 2 or 3 times. Not sure if those are sensations generated by the PM or not. I'm noting all my observations in a log, with date and time, to share with the cardiologist on my next visit. I'm hoping we can compare that with the data download from the PM and see if there is any correlation.

I'm also open to suggestions and concerns from people on this site. Thanks,

Lou

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