Comments to Bite-sized EKG #3: Basic Cardiac Physiology!

    • Hard difficult rhythm strip

      ST elevation / AV block / Junctional rhythm

      Not motivated at all

      • 😆 1

      • Lovely!

        How bad is the AV block?

      • image_transcoder.php?o=sys_images_editor&h=115&dpx=1&t=1675695081

        The electrical one, ST segment elevation with probably second degree AV block. P wave appears to be hidden within the T waves (yellow and black). As the conducted beat has prolonged PR interval with narrow QRS, it is likely AV nodal rather than infra nodal disease. Likely inferior STEMI affecting the AV nodal artery?. I believe the patient will be probably recover his normal rhythm with revascularization.

        the mechanical one: I was not expecting this delay (usually there is electromechanical delay that we notice on echo as well) from the QRS to the peripheral pulse plethosmography wave form (blur arrow). We do also noted stronger wave amplitude (red arrow) after the pause as well which is expected given longer LV filling time.

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        • Bingo! Nicely done!

          The two phenomena are:

          1. Electrical: Wenckebach type second degree AV block. Heart block is not complete (there is still R-R irregularities with group-beating). Baseline AV is quite long with next P hidden on the previous T makes it look peaked.

          2.Mechanical: Frank-Starling Law of the heart - After the pause, the stroke volume is bigger as this is likely due to a larger diastolic filling (due to missed beat). Hence, if myocardium is otherwise intact, the beat is stronger, as shown in Oximeter tracing.

          Although, there appear to be ST elevation, but on only one lead one need to be careful about calling STEMI. The motivated paramedics did keep the 12 lead EKG (below) which does not show acute STEMI, may be old inferior MI.

          The patient denied acute cardiac symptoms and was in a transfer between two hospitals for non-cardiac issues.

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        • What’s your explanation for the delay of pulse arrival time?

          Is it normal?

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          • Hard to tell. Remember, this is not an arterial waveform from an actual vessel, this is just a pulse oximeter with tracing being just a surrogate of arterial pulse. Not sure what technical factors involved there, but need to be live watching the actual tracing to troubleshoot that.

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