My 17 yr.old Son has Sinus Arryhthmia 41-180 BPM entire time of 48 hr monitor

I am so worried if this is urgent or dangerous! My 17 year old son has been having frequent chest pain with palpitations & dizzyness, causing him to have to sit down if he is (standing or walking) until it goes away, he gets this even when sitting or resting, so activity alone doesn't trigger it. He also gets a headache and dizzyness when he stands up, especially when he gets up in mornings. The main thing I am worried about is that he has been diagnosed with SVT on an EKG, but then on his holter monitor (48 hour) we got the results and it says on there that during the episodes of CHEST PAIN & DIZZYNESS he had SINUS TACH at 140 BPM, and an hour before that episode his BPM was 180 - So that confirms his chest pain is due to the sinus tach. And it says on the Holter Report that he has NSR with a Marked Sinus Arrhythmia throughout the entire 48 hour study. Heartbeats ranging from 41 to 180. Longest R-R is 1.62 seconds. and SVE: 1 PAC. We are still waiting for insurance approval for him to see cardiologist, it is taking too long, I am so scared for him! If anyone knows, PLEASE let me know if the constant Sinus arrhythmia with such a huge fluctuation in the BPM, Chest Pain & Dizzyness could indicate something urgent or serious. Also if anything else I noted here may be serious. Thank you for your help.

[is_something_wrong]

This did indeed sound bothersome for him.

We are not physicians and can't give him a diagnosis. First, it's really reassuring that 1) he didn't have any arrhythmia other than sinus arrhythmia, and 2) that Holter monitoring didn't reveal any pauses.

Something in your post is rather confusing. My 24 hour Holter revealed heart rate range between 37 and 186 BPM, and that's completely normal. My heart rate maxed at 186 BPM with exercise and dipped to 37 BPM during deep sleep. That's common in a young (?) healthy man like myself (I like to believe I'm still young even though I'm 30, hehe). So the 41-180 range itself isn't abnormal.

However, if you're saying that his heart rate is fluctuating from 41 to 180 all the time, even during rest, and this is causing symptoms, it's rather abnormal. Marked sinus arrhythmia is in itself a common finding among young men.

You can read this article concerning this:
http://chestjournal.chestpubs.org/content/82/1/19.full.pdf

A bit advanced, you can look under the tables "arrhythmias" and "sinus heart rates" to see normal values.

I can't help but suggesting that your son should be examined for sinus nodal dysfunction (tachycardia-bradycardia syndrome) if his heart rate keeps fluctuating, and especially if he have symptoms. But this disorder would usually cause long pauses (longer than 2,7 sec awake and longer than 3 sec during sleep) in the heart rhythm. Your son doesn't seem to have that.

Other causes must be considered as well, for example too high autonomic nerve system input on the heart, low or fluctuating blood pressure, nervousness, etc. I would assume your doctor already has considered some of those conditions.

[Mom2four85]

I know it's really scary dealing with things like this, I remember when my oldest daughter was 6 and fainted I panicked even though I had dealt with fainting and arrhythmias since I was 9 years old; dealing with your child having something wrong is different.

An Ekg showed SVT yet in 48 hours only 1 PAC was found; which is a good thing.  I would make sure he keeps a spiral bound notebook with dates, times, symptoms and what he was doing at the time for his doctor and see if you can find a pattern.

I would say much like Is_something_wrong and ask some questions.  Some questions as a lifelong arrhythmia and syncope (fainting) patient I would ask -

How is his blood pressure? Has he ever has any problems with it - high/low? Does his blood pressure coorelate with his arrhythmia's, chest pain or dizziness? i.e. he notices blood pressure is low/high with chest pain or arrhythmia's?

Does he have sleep apnea? some of the symptoms you describe sound like sleep apnea (headache dizziness esp upon waking) what are his sleep habits/patterns? does he get up to go to the bathroom at night? if so how many times normally?

What's his diet and water intake like? Has he had any blood tests to see what his electrolytes are? any abnormalities? Does he drink soda, tea, energy drinks etc caffeine?

anyone in either side of the family die early of unknown causes or either have genetic problems ?

has he been sick or had any infections or viruses?

I've had hr's @ 350-425 bpm during sleep then I can dip to 50 in a blink but I have a pacemaker/icd so I can't go any lower; but before I have had HR's in the 20's at the same time I've had hr's in the 250's range.  They think mine are due to the ANS (autonomic nervous system) and vagus nerve problems.

I would definitely see a cardiologist about this and keep the journal/log it may help figure out what's going on and pinpoint the problem.

[angelize]

Thank you so much for your post and for the helpful article link, I will look that up.
Also, the fluctuating heartrate is all the time; when relaxing, just sitting, or just walking through the store really triggers that plus the pain & dizzyness, so he hasn't been able to excersize at all with this. Since it is jumping back and forth all the time high to low is what really has our family physician concerned, along with his blood pressure problems - That is the other problem he is having, his blood pressure does fluctuate drastically from laying down to standing position. Blood pressure drops too low laying down and while sleeping, then when he stands up it raises way too high instantly, causing dizzyness and throbbing headache on top of his head. That was actually the reason our doctor ordered the EKG and then 48 hour holter test. How we found out was, one night he was sleeping at his friend's house and they found him convulsing in his sleep, they checked his heart and it was beating irratically, then suddenly stopped beating, then started again - they quick woke him, but he was delirious and never remembered any of it, he doesn't even remember being woke up. He seems very calm, and never worries about anything, and he doesn't like to tell me if he is having health problems, he doesn't like to worry me (I have health issues myself, and then my Mother died in May, which hit us all very hard, so my son seems to want to keep me from getting worried, even though I always tell him he & his health is more important to me than anything). So when his friend told me about what happened the next day, it scared me to death! (Although I try not to let him know how worried I am because I want to make sure he tells me any time he has heart problems). So anyway, when we found out about that episode is when we took him to the doctor and also started checking his blood pressure in different positions.
Thank you so much for listening and for your post. It really helps to hear from others so I know what to watch for, and also gives me ideas on what to ask his cardiologist when we can get him in there. I am checking with insurance today to see why it is taking so long to get the cardio. appt. approved.
Thanks again and take care.  

[angelize]

Thank you so much for your post, I really appreciate it.

Nearly everything you mentioned is all true in my son's case. I will go down the line and answer each one (We are trying to document everything, he forgets things alot so I have to keep asking him if he has had symptoms, also we are keeping track of his blood pressure and making notes for the cardiologist):

His blood pressure is actually what we noticed first. What happened is, he was staying at a friend's house and while he was asleep, his friends found him convulsing/jerking, they checked his heart, it was beating irratically, then stopped beating, they woke him up but he was delirious and didn't remember any of it the next day. So when his friend told me, we got him into our doctor and started checking his blood pressure laying down, and when getting up (because he told us then that he always gets and instant throbbing headache when he gets up in the morning along with dizzyness). We found the blood pressure drops too low when he is laying down, and suddenly rises too high when standing up. (I think the low BP when sleeping maybe triggered the bad arrhythmia and convulsing that night). So that is what prompted our doctor to order the EKG and 48 hour holter monitor, then he found these problems with his heartbeat suddenly raising and lowering 41-180 bpm for no reason, even when he is just relaxing, so our doctor said something definately isn't right and he needs to see a cardiologist. Just walking through the store triggers bad episodes where he gets the pain and dizzyness with it (Those episodes were caught on the monitor too with 180 bpm at those times).

He sleeps through the night, he doesn't get up to go to the bathroom until mornings, but he does have to get up slow due to the dizzyness and headaches that come on when getting up.

His diet is pretty normal (although he has lost alot of weight since getting so ill back in March - June, which is another question you brought up and I will explain more about that later). He used to drink sodas including mountain dew, but since the heart issues no more sodas or any caffeinated beverages. He drinks alot of water and gatorade now. He also craves salt since all this started, so he now eats alot of pickles and drinks V-8 juice regularily too. Our doctor recently ordered full blood count and labs, we are still waiting for results.

What really worries me; and is also so very sad and hard to talk about - Is that my first child, a baby girl, died at one month old from a major heart defect (the doctors just thought it was a hole in the heart when she was alive, and said she would get surgery when she turned around 5, and said she would be OK until then) So it was a devastatingly major shock one morning to find her passed away. They didn't know until the autopsy that she actually had major defects in her heart, once they found out what she died from, they said there was no way she could have survived and were surprised she lived as long as a month. I don't remember what the name of it was, it was a very long name, and that was many years ago, but they said it was very rare, and not caused by anything from me or her father, and not inherited, they said it just happens very rarely (like 1 in 500,000) for no reason. But that has really caused me to be extra worried about my son, and he is my only child. There are other heart issues in both mine and my husband's family (and myself - I am on metoprolol for PVCs, PACs, and other arrhythmias & tachycardia), both sides of our immediate family have histories of heart surgeries also. So a long heart history in both sides of family. And my Dad died of unknown cause when I was young, they said probably heart related (he was in his late 20's).

As for my son being sick, that is another thing I have really been wondering if it triggered or set all this off - In March-June he was very ill with: First a bad flu, then pneumonia, then he suddenly got 103.8 fevers, and even the hospital had trouble getting them down, they couldn't figure out what was wrong, fever kept spiking, he couldn't eat or drink, he was on IV fluids, then he got within hours a rash spreading over his body, so the hospital thought mennococcial mennangitis at first, but then they found out he had a severe case of Mono and his spleen was almost ready to rupture. They also had to put him on IV antibiotics. So he had all those illness back to back ending in severe Mono which took him many months of recovery, since then he has lost alot of weight too. And after that is when he said he has noticed many of the heart problems like the palpitations, chest pain dizzyness, headaches, etc. He had not been telling us because he didn't want me to worry because my Mother also died in May, and I am very chronically ill myself. (But I always tell him that his health comes first, and to always tell us everything from now on). So anyway we never knew about the heart issues acting up until he had stayed at his friends house that night and they told me about it.

It does seem alarming to me that the heart symptoms started after he was severely ill with Mono, etc. Do you think that could have brought on or triggered the heart issues?

He does also have chronic lyme disease, which was diagnosed a year late. He did have some palpitations, chest pain, etc. back in 2007 when diagnosed with the lyme, and the doctors at that time thought it was due to the late-stage lyme, and they said the heart issues would resolve with the lyme treatment, which they did, until the illness this year. (His lyme still flairs now and then too, it is still in his systom, so that may be another trigger for the heart issues too).

I know this is a ton of information, sorry it is so long, and I really appreciate you taking the time to read this. I am so thankful that you brought those issues up on your post, as it all seems to possibly be a factor in this.

Thank you so much for your time and information.
Take Care.

[is_something_wrong]

Your new information is a bit worrisome (the heart stopping during sleep and irregular heart rhythm during sleep). It's a fairly strong sign of sinus node dysfunction or "sick sinus syndrome" which manifest with fluctuating heart rate between tachycardia and bradycardia, pauses and irregular heart rhythm.

The heart stopping is probably not "cardiac arrest" as this is actually an extremely rapid heart rhythm that doesn't produce a pulse. Pauses occur, but luckily the heart has backup pacemakers that kick in after a while.

The irregular heart rate is probably/possibly atrial fibrillation which commonly occurs with SND.

The good news is, if this is the diagnosis, it's fairly easy treatable. The doctors insert a pacemaker set at 60 BPM which creates a "floor" in the heart rate, so the heart rate will never go lower than 60 BPM. The tachycardia is taken care of with beta blockers, dosaged so he will have a normal heart rate response to exercise, standing, etc.

The problem with this condition is that beta blockers alone may cause serious problems (without the pacemaker). I'm not saying this is the case with your son, but it should be considered.

The diagnosis is confirmed with an EP study if the doctor is unsure.

The heavy heart beats and headache isn't necessarily a sign of high blood pressure, but when the heart rate drops sharply, the heart beats will always be heavier, as circulation is still high. The blood vessels often have their methods of compensating this by dilating, so blood pressure will remain within safe limits, but not always.

I wish you and your son the best.

[Mom2four85]

oh my goodness; I'm so sorry to hear that...losing a child at any age is so difficult and even though the time fades; it doesn't ever really go away. I'm sorry I got so nosey and ask so many questions :(  It's very important that you know the specifics of her death and tell your son's doctor.  Also, it may be important to find out if you can about your father if you can.

you've really been through the ringer with tragedies haven't you? any time you need to talk, send me a PM and I'll try to get back to you; even if it's to vent or cry.

I was 23 or 24 weeks pregnant back in Nov 1997 and a doctor didn't listen to me when I told him how sick I was; I should have complained more.  I ended up having my son way too early because I developed Group Beta Streptococcus, which went into my blood stream causing all kinds of problems (blood sepsis); he died the next day and I was dealthly sick for awhile in the hospital and almost didn't make it.  I still wonder what that did to my body and how much it plays a part in my health issues.

I digress; sorry to ramble. I would take all the tests and reports and go to a large clinic like Cleveland, Mayo or Vanderbilt etc,  esp with your family history and current problems.  I don't know how much how Mono can affect the heart, but I do know Lyme can cause problems like arrhythmia's and nervous system problems.  

The best advice I can give, is to keep accurate daily notes, ask as many questions as you feel you need to until you find the right answers and get your son well and treated.

I really hope you find some answers soon for your son; let us know how things are going and what the dr's say or if you have any other questions/issues.
~Lisa

[angelize]

Lisa,
Thank you so much for taking time to read my post and family history with the heart problems and all. I really appreciate your feedback, knowledge, and your kind words.

Do you know if sick sinus syndrome is very serious? Is that something we should be watching for any emergency symptoms? (Just encase that may be his problem). Also, is a pacemaker a major surgery to get implanted? Please let me know if you have any answers or any further advice on those, so I will know more of what to expect if it is that, or what other things to watch for.

I am so sorry to hear of what you went through too, I know that losing a child is the very hardest thing for anyone to go through. And being so sick through it all also had to be so hard, my heart goes out to you. That is terrible of the doctor not listening to you when you knew there was something wrong! Sadly, there are way too many doctors like that and it is such a tragedy. Everyone knows their own body, and if they feel something is wrong, the doctors should listen to their patients and do everything they can to figure it out.

I agree with you, I do think that such a severe illness can cause alot of other issues, it seems that in some cases when our bodies get severely ill with a virus or something, that does something to our immune system and weakens us to the point that it invades certain parts of our body or organs and does permanent damage (that is what happened to me when I got lyme disease, ended up in the hospital extremely ill, they couldn't figure it out until a few years later, by then I couldn't walk any more, then they gave me IV antibiotics, then oral antibiotics, I improved for a while but after antibiotics were stopped, I went down hill worse and worse, now permanently ill and nothing helps any more. The damage is done.

I am here for you too, if you ever want to talk. I am not sure how the private email works, but I will look into figuring it out. I am still new to this website, and I am so glad I found it! What a great source of information, support, and help! You can send me a PM any time you want, then I should be able to figure out how to PM you back. I look forward to hearing from you, and I really appreciate your posts.

Sometimes it may take days for me to reply because many days I am too weak to just sit up in bed and type on the laptop, it is just hard to turn over in bed many days, and I sleep the days away, when the fatigue is very bad, then I lay awake most of the night after a couple days of sleeping. So that is why sometimes I can't reply for a while and when I do it is sometimes at odd times in the middle of the night. Those are my worst times for worrying about my son's heart problems, so it is nice to have this forum/community to turn to.

Please know that I am grateful for the questions you asked because those are some things that I now know to bring up to my son's cardiologist, that I wouldn't have thought of before, so that is very helpful to me. And your replies also give me information on other things to look up and research too, and then I can learn of more things to watch for in my son. I am grateful for all of your posts.

Because of so many of my family and my own experiences of not being properly diagnosed, I have since learned to make it a priority from now on to always do my own research, along with seeing what the doctor says when it come to health issues, then if there are things that the doctor isn't checking into or can't give us answers to, then I know it is time for a second opinion. Life is way too precious to take a chance on misdiagnosis or undiagnosis - It happened to my first child and my mother, which ended up costing them their lives. It happened to me and my son with the lyme disease diagnosed too late, which possibly caused his heart issues, along with pain and numbness periodically. And it caused me to be mostly homebound/bedridden with severe chronic fatigue and constant pain, severe migraines, heart problems, bone & muscle degeneration/weakness, permanent nerve damage and neurological problems since 2007. After working 18 years manager at a wonderful job, always on the go, and outside activities with my family, etc. - To a life of spending the last 4 years confined mostly to bed, and only getting weaker, and I am only 42 years old. So it is very hard, but I can endure as long as my son is OK, he is my reason for continuing to try to fight this illness. But I could never do it without my wonderful husband, he has taken over all housework, meals, and takes us to our doctor appointments, so he is a real blessing.  

It is so nice to have someone to talk to, I want so bad to be able to pick up the phone and call my Mom, she was always there for me and we talked every day, any time I was worried or when I was having extra bad days, she would be right here for me. Since she passed away a few months ago (from fast growing cancer which was diagnosed way too late) I am so lost without her.
My husband doesn't like to discuss our son's heart problems, I think he just has trouble accepting it and he doesnt understand any of the medical terms. And since I have been ill for so long, my friends have pretty much forgotten me or just given up on me. I sleep so much due to severe fatigue and pain. So I am pretty much alone in trying to cope with, and research my son's heart issues. It breaks my heart so bad to think of what may be wrong and I am constantly stressing and worrying about it to the point of crying myself to sleep. And of course the extra stress is making my arrhythmias come on all the time now, but that is ok, I just want my son to get better.

We are still waiting for the insurance to approve his cardiologist appointment, I called and they said they will now put a rush on the request, I hope they get him in soon!
The cardiologist does sound like a good one. I will have all the notes and questions ready for him, and the sheets that my son is keeping track of his symptoms, pulse, blood pressure, to give to the cardiologist when he sees him. I will look into the other things you mentioned also.

I will keep you updated on anything new I find out with him.

Sorry my posts end up so long, it is hard to mention one thing without the other, and then I end up going on and on. It sure is nice to be able to let it all out to someone though. I miss talking to everyone (my mom, my friends, my former customers, etc.) so I am really thankful to have someone to talk to, especially about my son's heart issues because it is eating me up inside.

Thank you again for listening, and for your time.
I am so thankful for all your replies.

Take care,
Julie

  

[angelize]

Thank you for reading my updated information, and for the information in your reply, I appreciate it very much.

(I got mixed up and replied with the questions I have on the sick sinus sydrome in my last reply post, I meant to ask those questions to you, as you mentioned that as a possibility in your post) -

So just encase the sick sinus syndrome may be a possibility, do you know of any additional symptoms I should watch for, or anything I should tell my son to be aware of or limitations on any certain activities?
Is that something that could get worse the longer not treated?
Is there any symptoms that could come with that which could be serious that we should call ambulance or get him to ER?

Also, is a pacemaker a major surgery to implant that?

I understand that it is only a possibility that he may have that sinus syndrome, but I just want to be sure and find out things to watch for, etc. just encase.

If you have any other information on that, or anything you can think of please let me know if you get a chance.

We are still waiting for the cardiologist appointment, so I want to make sure my son will be OK all this time it is taking to get that appointment approved, and I am hoping and praying things don't get worse during this time we are waiting for him to get in and get diagnosed.

Thank you again.
I really appreciate your helpful information.

[Mom2four85]

Julie; I completely understand.  I've gone through fainting episodes and arrhythmia's since age 9, so it was a bit of a shock that I had anything wrong at the age of 42 when I had an abltion.  My problems were blamed on everything they could think of growing up....wanting attention to stress, anxiety not sleeping etc.

Before the procedure, I was full of energy and the chest pain, shortness of breath and arrhyhthmia's never really bothered me...I would faint get back up and just go on because I really believed I was fine.  I came out of surgery and could barely function when a few weeks before I was walking & running daily and felt fine.

I've found anything is possible - they said I had a "normally" structural heart and then not so normal then back to normal again and when I question this dr's have no answers.  For some of us, finding what's wrong and getting answers is a long difficult process of elimination.  It's been 2 years and I'm no closer to finding what caused my problems than I when I first started and that's going through just about every test under the sun.

I had a pacemaker/icd implanted because I'm very much like your son...I suffered profound bradycardia and then high rates of ventricular tachycardia...I could go from 20 - 200 in a blink and then my heart would be fine and then start all over again.

I only know about SSS because searching for myself and asking questions; it seems dr's know very little about it and what causes it and it's a very uncommon thing.  I've gotten it's a possibility but unlikely since  my sinus node was fine when they did my ablation (I think that's what it's called).  An ablation may yield some answers and be able to pinpoint the problem; so hopefully insurance gets his approval through quickly.

The pacemaker/defibrillator implant was relatively simple; I think less than an hour for the actual implant but you're in there longer for prep then recovery etc.  The worst part is keeping your arm in a sling after and not using it much for the first few weeks.  With mine; I had complications from the lead placement from the beginning and couldn't use it almost 12 weeks.

he may also benefit from the ICD because it will help regulate the higher heart rates; normally mine will feel like a "twinge" in my chest and I can feel it working; if you want to see it - google Boston Scientific Teligen 100 - it's extremely small and after awhile you never know it's there.  something to ask his cardiologist/ep about if an ICD not just pacer would benefit him.

If you click on someone's name you'll get their profile and you can send a message or leave notes and read journal entries and see their trackers etc =)

Like you, if I don't answer it means I'm not feeling well and probably in bed or on the couch. I'll go days and be fine; no numbness, tingling, pain or problems then a week I'll not be able to sit up or move even with meds.

hopefully someone else will have answers about SSS; or something comes to mind from someone else who's gone through something similiar =)

[is_something_wrong]

Hello,

I would say (but this is advanced electrophysiology and I'm, as you know, just a volunteer here, not a doctor) that the main risk with SSS is fainting during pauses.

Just a little correction to Lisa (sorry...) an ICD will not help treating sinus tachycardia, even at high heart rates (above 200). It will reset the heart rhythm and provide a shock, but after a couple of seconds the rapid heart rate will continue and the only thing done is causing pain from an electrical shock. You (luckily) can't stop the sinus node with an electrical shock, so you can't stop sinus tachycardia.

An ICD will only help when you have reentry arrhythmias or fibrillation.

SSS can get worse or even better. It's important to find the cause, is it in the heart, or is it too high autonomic input on the heart? Too high or abnormal autonomic input may cause a variety of arrhythmias; SSS, inappropriate sinus tachycardia, inappropriate sinus bradycardia (where SSS is a combination of the two), POTS, etc..

As I said, the heart usually have backup pacemakers to take over during pauses. Unfortunately, some of the rhythms those pacemakers can produce are arrhythmias, and one of them is actually atrial fibrillation, which is not so nice. It may also take a long time before the backup pacemakers kick in, which may cause fainting.

A pacemaker implant is not a major surgery to implant. It's done when the user is awake and it usually takes less than an hour.

I would ask the doctor for another Holter, to see if the heart rate variability is still there, and for trying to capture any pauses. I would also try to see a cardiologist as soon as possible.

As far as I know, SSS isn't a life threatening disease but it's something that should be treated. If it's not SSS, you need to find out what it is. I suspect that a cardiologist is the only one capable of doing that.

Keep us updated and best wishes to you and your son.

[Mom2four85]

Is_something_wrong my ICD has therapy that treats VT episodes; at least that's how they explained it to me and what my interrogations show...ATP therapy then if not I get a 17J then a 46J shock to reset the rhythm/rate.

My unit says: Tachycardia Treatment Setup
TELIGEN is the first ICD to offer a 2-zone nominal therapy structure with ATP and rhythm discriminators nominally ON.

TELIGEN provides a robust sensing algorithm that takes the best elements of Brady and Tachy sensing to form a common sensing algorithm with enhanced signal filtering and processing.

Quick Convert™ delivers a burst of ATP in the VF zone to avoid painful shocks for pace terminable VTs below 250 beats per minute.

I'll ask the EP to explain again but that's how mine was explained to me...who knows I probably have no clue what I'm talking about and misunderstood the EP.

[is_something_wrong]

You are completely right ;) By the way it's good your ICD converts VT with overdrive pacing and not shocks, as this will make your life far better (avoiding the shocks except when you're in VF or non-paceable VT)

The problem is, sinus tachycardia and other arrhythmias caused by increased automaticity can't be shocked. They can, but the arrhythmia will continue 2 seconds later because the underlying cause (which is a really upset spot in the heart) still is there. The sinus node is supposed to be the most irritable spot, that's why we have a sinus rhytm an not a mixup of atrial rhythms, ventricular rhythms, junctional rhythms and other unpleasant stuff.

A sinus tachycardia is a cause of an "annoyed" sinus node. When exercising, the sympathic nerve system is "whipping" the sinus node and when we're anxious, adrenaline is doing the same (or a combination). With inappropriate sinus tachycardia, this "whip" is constantly active. A shock will cease the whipping for a couple of seconds, but the whip is still there.

Using the same logic, you can't convert atrial tachycardia or sinus tachycardia with adenosine.

[Mom2four85]

oh I don't even want to think about it if I didn't have the ATP; that's one reason my EP went with this unit over others...but it's bothersome that the anti tachycardia therapy doesnt work on all tachy's...I thought it did but may explain why it doesn't work for me all the time...