The Skeptical Cardiologist

What is Causing Your Cardiac Flip-flops? PVCs Revisited with Kardia’s Advanced Determinations

The skeptical cardiologist woke up in the middle of the night recently and noted that every 30 seconds or so he felt like someone or something had briefly squeezed his heart. This awareness of the heart beating (a palpitation) I knew to be from premature ventricular contractions or PVCs, something I’ve experienced in the past (and written about here and here) when stressed or overly hyped on caffeine.

I confirmed the renegade ventricular contractions by palpating my radial pulse and noting that concurrent with the flip-flop in my chest there was a delay in the pulse (the premature beat is less forceful) followed by a stronger beat, (the post-PVC beat has prolonged time for filling resulting in a more forceful contraction.)

Even though I knew my flip-flops were benign I found that they disrupted my ability to fall back to sleep. My cerebral cortex began assessing what might have brought them on and then pondering miscellanea.

In the past I’ve documented my PVCs by using my Alivecor Kardia ECG. For patients with Kardia devices who can’t interpret ECGs, however, diagnosis of PVCs heretofore had remained elusive.

Fortunately, now for those with unexplained palpitations, Alivecor’s recently released Advanced Determinations algorithm identifies both PVCs and premature atrial contractions (PACs.)

I had a little too much coffee this morning and began feeling the PVCs again and made a recording on my Kardia single-lead ECG.

Lo and behold, the Kardia AI algorithm had correctly diagnosed my PVCs! It even placed a black triangle right on top of the nefarious beat.

Six normal (sinus) beats followed by at the early occurrence of a PVC (within red circle) followed by a pause

The PDF of this ECG can be shared by email with physicians or friends.

My posts on PVCs and their treatment continue to gather hundreds of views daily and readers have left many descriptions of their experience with these pesky contractions.

In particular, PVC sufferers are interested in what might be causing the extra beats and what they can do to reduce or eliminate them.

Certainly, being able to personally and independently document the occurrence of extra-systoles with Kardia’s Advanced Determinations algorithm should provide insights that will provide some answers to causes and effective treatments.

Personally, I’m still racking my brain on what brought my PVCs back: Was it the new cocktail I drank? Was it those Peanut M&M’s I snacked on?

If you are using the Kardia with Advanced Determinations please share your experiences in PVC and PAC detection so we can get a better understanding of how it is working in the real world.

It should be noted that the Apple Watch ECG algorithm is incapable of identifying PVCs or PACs and Alivecor stands alone as a reliable, FDA-approved resource in this space.

Deterministically Yours,


N.B. The new cocktail was The Aviation (gin (the botanist), maraschino liqueur fresh lemon juice and crème de violette liqueur). The peanut M&M’s contain chocolate which contains significant amounts of the methylxanthines, caffeine and theobromine. These chemicals have complex effects on both the neurological and cardiovascular systems.

Interestingly, even though conventional wisdom in cardiology has tied methylxanthine consumption to cardiac arrhythmias and I’m convinced my PVCs can be triggered by episodic excess caffeine or chocolate consumption, this 2016 paper did not find such an association with chronic consumption:

In an investigation of nearly 1400 older adults, we found no evidence that the frequency of habitual coffee, tea, or chocolate consumption was associated with cardiac ectopy before or after multivariable adjustment.

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