Apple iWatch for ekgs is not perfect

I was driving and suddenly felt a worst than pvc sensation...tachy and arrhythmic. I couldn’t drive and use my Kardia at the same time so at a red light I took an Apple Watch reading which said AF..not the usual inconclusive with pvc. I sent the ekg to Dr natale NP because I was planning to stop multaq and if in AF the plan would change. She said it was PVCs and not AF. That watch is not accurate. It made me doubt my successful ablation. So just a heads up if you take a iWatch reading...you may get a false positive.

Apple Watch: Doctor sues Apple for violating atrial fibrillation patent Here is the doc's patent.

Though the patent covers a number of methods, it looks like Apple measures radial pulse using light. It then analyzes the data, looking at the pulse rate variability to determine whether it is afib. There are some issues here. One is that the pulse wave amplitude varies from beat to beat - you can see this using a plethysmograph app on your phone (uses the light and camera to show pulse wave amplitude). Also runs of PAC's and PVC's can look similar to afib.

I used a recording Polar heart rate monitor for diagnosing afib, but I was doing it visually looking at the patterns. The heart rate monitor rate is based on ECG not plethysmography so does not have the pulse wave amplitude issue. Using the Polar device and graphs are discussed here and here..

Generally afib presents with a highly variable pulse rate from beat to beat. The only issue is that other arrhythmias can present similarly. Many visual examples are in this file courtesy of Mark Robinson, a former prolific poster from the UK. Note, all these graphs are beat to beat heart rate vs. time.



Edited 1 time(s). Last edit at 12/30/2019 07:11PM by GeorgeN.

George:

(the ekg shows the atrial activity, for example fibrillation, but the stethoscope doesn't. From the valve closings that we
hear with the stethoscope, we don't know for sure if the atria are fibrillating. It seems that the best we can do is to listen
with the stethoscope while connected to an ekg and look for correlations between the stethoscope and ekg in order to
be able to identify afib later when using the stethoscope alone).

Is this saying that when a doctor or their assistant is using a stethoscope they can't for sure know if a person is in AF?

Liz

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Elizabeth
George:

(the ekg shows the atrial activity, for example fibrillation, but the stethoscope doesn't. From the valve closings that we
hear with the stethoscope, we don't know for sure if the atria are fibrillating. It seems that the best we can do is to listen
with the stethoscope while connected to an ekg and look for correlations between the stethoscope and ekg in order to
be able to identify afib later when using the stethoscope alone).

Is this saying that when a doctor or their assistant is using a stethoscope they can't for sure know if a person is in AF?

Liz

I've only listened to my heart in afib with a stethoscope once - my first afib episode which presented while I was taking my blood pressure with a manual cuff and stethoscope. It was the weird sounding pulse that caused me to pay attention and ultimately led me to go to the ER as I had no idea what was happening. I can't say whether a doc can tell with just a stethoscope, however I think it would be subject to the same limitations that an Apple Watch or the Polar would have. The doc gets a sense of the beat being unsteady, however that can have multiple causes. Five years ago, I posted this with a couple of links to images on an iPhone plethysmograph app. If you look at the range of values on the Y axis, you can see how much wider it is in afib. This is also what a doctor would hear. He could suspect afib, but likely not be able to confirm it without an ECG and ideally a 12 lead ECG

Isn't listening to the heart with a stethoscope easier with a skinny patient ?

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Pompon
Isn't listening to the heart with a stethoscope easier with a skinny patient ?

Yep.

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Carey

Isn't listening to the heart with a stethoscope easier with a skinny patient ?

Yep.

Okay. I may believe my GP when he says he hears my ectopics.

Happy New year !

Oh, no question that ectopics can be heard.

But really, all one needs to detect afib is a couple of fingers. The irregularly irregular pulse of afib is unmistakable and no other arrhythmia produces that. So just feel your pulse for 30 seconds and if there's just no predictable rhythm at all, you're in afib.

30 seconds if fine, but I can tell in 5 seconds with fingers on my carotid pulse.

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Ken
30 seconds if fine, but I can tell in 5 seconds with fingers on my carotid pulse.

That's what I do. Unmistakable.
I'm so used to the sensation of afib in my throat and chest that checking my pulses with my fingers is just to comfirm the sensation.
Laying on my back or on my left side increases the sensation.

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Ken
30 seconds if fine, but I can tell in 5 seconds with fingers on my carotid pulse.

I concur. Like the old "name that tune," "name that rhythm in 4 beats or less..."

I can try to delude myself when taking a radial pulse at 3 AM, "that really isn't afib, I don't need to take flec." This is when a monitor is handy. I have a hard time denying that is afib when I see the ECG, a HR vs time tachogram or even plethysmograph output.



Edited 1 time(s). Last edit at 01/02/2020 11:12PM by GeorgeN.