Echocardiogram, Sonogram, MRI or CT imaging, occasionally it might show up on an xray , A very very Unstable and decreasing Blood pressure (spiraling downward) 120/80 is generally Normal/perfect above is the norm in older folks say it begins at 140/90 and is 60/30 within several minutes YOU know this person is Bleeding out of SOMEWHERE internally.....
or during an open surgery... ..There are numerous caused to AD as well, so They cane be caused BY out of control BP , genetics , Peripheral Artery or Vascular disease (PAD OR PVD), Trauma Car accidents or Motorcycles falls from horseback or HIGH falls anytime you have velocity and come to an abrupt stop the heart is suspended from the Aorta and Vena Cava Which can tear as it pendulums forward. also STress and strains , even (Syphilis) . Marfan's Lowey dietz and so on...