Please view the following animated video tutorial on the Non-conducted PAC.  There is also an optional audio file which may be utilized at the same

Now let us return to the concept of PAC. A PAC occurs when a focus of the atria becomes irritable and discharges early in the cycle,

Please see the animated video below with optional audio covering the Non-Conducted PAC (Premature Atrial Contraction).  The audio may be played simultaneously with the video.