ELN and aneurysm: However, in the presented study, AAAs were also separated by terciles, based on the authors’ theory that AAAs with very low ερ+ ̄/PP, indicating very stiff aneurysms, likely have a high collagen crosslinking that would allow for adequate strength to resist deformation during pulsation and further expansion, and that AAAs with very high ερ+ ̄/PP, indicating soft aneurysms, likely have near physiologic levels of elastin content that would allow the aneurysmal wall to incur high strains during pulsation, but still return to a diastolic baseline diameter without baseline expansion.