The еtiology for rupture of the left atrium is uncleаr, but probably is related with the high pressure in the left and right atrium and the so
called jet lesions from the mitral and
tricuspid regurgitation.
From here, the impulse takes a brief pause at another node of specialized cells
call the atrioventricular (or AV) node located at the junction where the atrial septum, ventricular septum, mitral valve, and
tricuspid valve meet.