My son has a slow HR

[Annie501]

My son is 5 years old and has a resting HR of around 55/60 bpm.  When he exercises, it does not increase by much.  He recently did a 6-minute walk which showed his oxygen sats stayed normal above 97 but his heart rate never went beyond 70 bpm.  He also did a pulmonary function test which was okay.  The day before all this, he met with his cardiologist who reassured me his heart was okay.  The echocardiogram revealed a slightly enlarged heart which he thinks is due to the slow HR.  The EKG revealed a skipped heart beat.  My son has trouble with exercise intolerance and tires very easily.  His cardiologist has no concerns and compares his heart to that of an athlete but he does not have the endurance of an athlete. His pulmonologist is concerned about this. Why is he tiring so easily and why isn't his HR increasing very much with exercise?  He is on Prevacid, Zyrtec, Singulair, Pulmicort and Genotropin.

[itdood]

Hi Annie, Sinus Arrhythmia is perfectly normal.  The younger we are, the more pronounced it is.  When we inhale our HR speeds up a little, exhale it goes down.  It makes gas exchange in the lungs more efficient.

I wouldn't rely solely on Internet research to eliminate the possibilities.  Check off what you can then go through what remains, his doctors would have to help you with some of them.  I'm sure his medical team has already run through this process as-well.

[Annie501]

Thank you for the information about the DD list.  Once I eliminate, do I just research via the internet?  Also, you seem to have some insight, do you have a medical background?  I'm still waiting to hear back from the doctor's...they were supposed to discuss my son's case.  It's been a week, I may try calling them today if I don't hear from them soon. One last thing, his cardiologist told me a few years back that my son has a sinus arrhythmia.

[itdood]

Hi Annie, thanks for elaborating, it paints a much clearer picture.

Coupla things I can think of further, a pediatric endocrinologist might be able to see if his HgH is staying in range and modify his dose accordingly.

Another idea is a pediatric stress test which might reveal more than the walking 02 sat.  For activity like walking he might stay in a good range, but when the stress is turned up you might find the point where it reaches a limit.

The skipped beat (PVC) isn't uncommon at his age.  I don't think there's much clinical significance to it.

The things you have to worry about when pediatric bradycardia presents itself becomes the "rule out list".  Also known as "differential diagnosis", perhaps you've seen this process at work on the TV show House.  This is a process of elimination.  I searched the DD list and here's what I came up with below.  You could probably scratch most of these off your list right away.  Others might be more areas to explore.  Best of luck to you and your Son!

DD list.  Rule out what you can, keep investigating stuff until it can be ruled out.  What you're left with is hopefully the root cause and is treatable.

Vasovagal response
Drug reaction
Sinus bradycardia
Hypothermia
junctional escape beats
Congenital heart disease
Sepsis
Obstructive sleep apnea
Electrolyte abnormalities
AV node blocks (second- and third-degree)
Idioventricular rhythm
Hypothyroidism (myxedema)
Allergic reaction
Increased intracranial pressure
Sick sinus syndrome
Psittacosis, typhoid fever, Lassa fever
Myocardial infarction

[Annie501]

He doesn't have just one condition.  He was born with multiple anomolies.  He stopped growing inside the uterus and I was induced at 35 weeks.  He weighed 3lbs 3oz at birth.  He was born with a hole in his heart which closed on its own but he did have surgery to close a PDA (patent ductus arteriosis).  He always had a slow HR even before the HgH (just started in Nov.).  He has an underdeveloped right lung, this is the main reason for his asthma meds.  We've tried weaning him from those in the past and found that he needs them.  The Zyrtec & Singulair keeps him dry and from post nasal drip, which causes irritation to the lungs, which causes him to cough so much that sometimes he throws up.  When this happens, it sometimes causes aspiration, which has lead to pneumonia.  He gets pneumonia quite frequently.  He's also on a feeding tube but only through the night now.

[Annie501]

Yes, he does know that and he said we would need to keep a close eye on his heart, as the HgH can cause a thickening of the heart.  If this happens, he would need to discontinue the meds.

[itdood]

p.s., does his cardiologist know he's on HgH?  I'm surprised he/she didn't pick that up and discuss it with you.

[itdood]

Treating him for acid reflux, allergies, asthma, pulmonary dysfunction, and I haven't heard of giving a 5 year old HgH before though I'm sure there's a good reason.  It sounds like there's a lot going on for him, what's his condition?

My money is on the HgH for the enlarged heart, though I'm just guessing.  An enlarged heart is a side effect of the HgH.  An enlarged heart will remodel itself, often causing arrhythmias (ex, PVCs and brady).

If his pulm function is normal, I'd rethink all those respiratory drugs too.  All drugs have side effects.  Sometimes the side effects might be worse than what you're treating him for.