I keep a little, ever-expanding note on my phone where I jot down little morsels of goodness that I pick up while listening to or reading one of the many excellent sites/podcasts in the useful resource section. They’re useful in a kind of “board review” way. I tend to skip the really basic stuff and try and focus on what I didn’t know.
I’ll try and transfer them here for your enlightenment.
From K Wang on HQMEDED
The basics on retrograde p waves
a junctional beat is one occurring from the AV node
normally narrow with no preceding p wave
the impulse travels down from av node causing the narrow complex qrs
an impulse also goes up from the av node and depending on whether the atrium is refractory or not will result in a retrograde (usually inverted p wave)
Example here from LITFL of an accelerated junctional rhythm with retrograde p waves(inverted p waves in II, III and aVF)