U wave and QTc elongation

[ventana]

Got a lesson from a patient today on this

some smart cards PA want to offer up some more info?

 

What a causes it?

Is it really Qtc elongation?

[UGoLong]

1. I've been in cardiology for a while and have read several theories on U waves but, as far as I know, there is not a settled explanation.  U waves can be congenital and can also be paroxysmal, such as in hypokalemia, hypercalcemia, hyperthyroidism, and marked bradycardia, as well as with some drugs. Congenital long QTc is another possible cause.

Three contending theories from https://litfl.com/u-wave-ecg-library/:

• Delayed repolarization of Purkinje fibers
• Prolonged repolarization of mid-myocardial “M-cells”
• After-potentials resulting from mechanical forces in the ventricular wall

2. QTc prolongation (many limits quoted; we generally call it for QTc > about 500 msec) can have a congenital origin or be from drugs. Some of the biggest offenders are antiarrhythmics, proton pump inhibitors, and various psychoactive drugs, however there are many other contenders. I use the Credible Meds application on my phone to review a patient's meds when I run across the condition. 

Hope this helps.

Edited November 21, 2019 by UGoLong

[MediMike]

Some weird correlation with intra-cranial processes too.

[Mayamom]

There is also a Prolonged QT web site.  In my experience mostly medication related.  Because most people are on too many meds these days. 

[surgblumm]

I have seen this many times on patients with HCM and when I am writing orders in the PACU I am careful to check the qtc's as many of the antiemtics are contraindicated and can cause Torr sades De Pontes.'