QT prolongation -anyone know about hearts?

[Ragusa]

Before I start I should say I will discuss this with GP.... but wanted to see if the mumsnet massive could give any views.

Dd 7 had a fever last couple of days. Much better by yesterday evening if a bit wan still.

This morning she came into our bedroom alarmed that her heart was beating really fast (we timed, it was about 150bpm and could be clearly felt without needing to do the finger on pulse thing).

This lasted 5 minutes or so and then gradually went down. By time we got to A&E as directed by 111, it was measured at 115bpm so not very alarming.

ECG reported as "sinus tachycardia otherwise normal ECG".

However (and here is my q at long last)...

QT interval at Heart Rate of 115 was 352 m/s and QTcBaz is given as 486 m/s.

Is that in the normal range?

Am not usually overworried about health stuff but my friend at school (probably) had undiagnosed Long QT syndrome and died aged 17.

Or is this likely to be measurement error, a.one off, or nothing at all to fret about. Doc did see us, but didnt refer to ecg at all. Presume she would have if anyrhing was remarkable.

I've calmed down a bit since this morning, DD has been bouncing on the trampoline so I think she is fine. Still interested to hear views if anyone has experirnced a child waking up with this.

Normal QT interval is 360-440m/s in an adult so I think that her QT is normal.

@HippyChickMam ta. Done a bit more research googling, but I am a scientisty-type and it seems the conversion used on the ecg report is unreliable where BPM is over 100. So I can unclench a little :)

But I also read that QTc should be close to adult ranges in school age children.

It is hard to rationalise when your personal experience has sensitised you... my friend's 2 siblings were all subsequently found to have a mutation, and banned from strenuous exercise and put on drugs.

If anything her QT is slightly short but that would be expected with an increase in heart rate. If you're concerned and given that she had an unexplained episode of tachycardia you could ask your GP to refer her for a 24 hour ECG

If you are concerned I would definitely ask to see a paediatric cardiologist. As you know, these types of arrythmia are rare, but they do occur.
I have CPVT which is a major cause of SD in children and it would have gone undiagnosed if I hadn’t had a 24 hour ECG and exercise stress testing. I had see a cardiologist privately because my Drs dismissed my symptoms as anxiety, but I had a sense that my heart was not behaving normally. I now have an ICD and antiarrythmic medication.
Far better to put your mind at rest than worry about it.

I suggest you talk to SADS UK,a charity that specialises in these sorts of heart problems. They have a wealth of knowledge and will be able to reassure you and let you know what help is our there. It's worth a phone call?

Glad your daughter is feeling well :-) but, I would ask to be referred to see a specialist, just to be on the safe side.

OT, but Ragusa, if your friend's siblings had a mutation (the same one?) then was it just a co-incidence that they all had it? As far as I know (a family member has Long QT syndrome) if it's due to a mutation it's not hereditary/genetic.

@HippyChickMama ok, I really muat be tired today as it looked on the long side from my researches!

@IrisAtwood my uncle has an ICD. What an amazing bit of kit they are, if a bit .... whoaaa to think about. Glad you were found out.

@ingredients, lazy explanation on my part. It was inherited, I thinnk it is usually autosomal dominant and sure enough the siblings and the one parent who was around was also affected but had had no symptoms.

@CoddledAsAMommett that is an excellent idea, thank you.

Corrected QT is an estimation of what the QT would be if the heart rate was normal. Bazette's formula, which is what QTc-Baz means, is not necessarily reliable in children because it's normal for them to have a faster heart rate and respiratory rate than an adult. So yes, the corrected QT is slightly prolonged but I wouldn't worry too much, using other formulae it would probably be shorter. As suggested, ask your GP to refer for a 24 hour tape and an echo.

@HippyChickMama thanks again, and to all who have replied. Calmer now. Hearts=scary

The machine interpretation don't always work well for paediatric ECGs. My personal practice is always to work out the QTc (QT corrected for heartrate) by hand/calculator to double check. Ask your GP about it, because the machine one is a bit long, but it's probably just a machine error. But a repeat ECG looked at by an actual person can put your mind at rest.

Viral myocarditis - google it!

Ask for an echo and a blood test if you are worried

If she had any long QT wave on her ecg, it wouldn’t have said ‘normal’ ecg with tachycardia. It would have picked that up.

The report simply says normal, but fast heart rate.

Obviously it doesn’t say why it is fast but I would just keep an eye on it. Could be just post viral

No, a QTC of 0.486 is a little bit long. Not "OMG there's a problem" long, but "need to check if the machine has calculated it correctly, and if so repeat the ECG" long. Upper limit of normal is (for most ages of children) 0.45.

For 0.486 I would definitely work it out by hand, and if not happy with the number would repeat the ECG. Almost always everything is then reassuringly fine. But not something I ever take the chance on. So it IS worth discussing with the GP.