ORIGINAL ARTICLES  VASCULAR SECTION 

The Journal of Cardiovascular Surgery 2003 February;44(1):67-77

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Effect of thrombus on abdominal aortic aneurysm wall dilation and stress

Thubrikar M. J., Robicsek F., Labrosse M., Chervenkoff V., Fowler B. L.

Heineman Medical Research Laboratories Carolinas Heart Institute Carolinas Medical Center Charlotte, NC, USA

Aim. Our ­goal is to under­stand ­how a ­mural throm­bus ­may influ­ence ­the pres­sure trans­mit­ted to ­and ­the dila­tion expe­ri­enced by ­the abdom­i­nal aor­tic aneu­rysm (­AAA) ­wall.
Methods. Two ­intact AAAs ­with ­mural throm­bus ­were ­removed ­from ­patients ­and pres­sur­ized to 100 mmHg. The pres­sure ­was meas­ured ­using a ­micro-­tip nee­dle trans­duc­er insert­ed in ­the aneu­rysm ­wall ­and ­advanced ­through ­the throm­bus. In 1 ­patient ­with ­AAA, sim­i­lar meas­ure­ments ­were ­made in ­vivo. Also, in ­vitro, in ­the ­two aneu­rysms ­the dila­tion as a func­tion of pres­sure ­was meas­ured ­using ­the mark­ers on ­the sur­face ­before ­and ­after ­the throm­bus ­was ­removed.
Results. Both, in ­vitro ­and in ­vivo, in ­the pres­ence of ­the throm­bus ­the pres­sure trans­mit­ted to ­the aneu­rysm ­wall ­was 91±10% of lumi­nal pres­sure ­and at 6 mm ­from ­the ­wall it ­was 96±5%. The aneu­rysm dilat­ed ­more in ­the pres­sure ­range of 0-40 mmHg (2-8%) ­than in ­the ­range of 40-100 mmHg (0.4-1.8%). Upon remov­al of ­the throm­bus ­these dila­tions ­increased sig­nif­i­cant­ly to 4-15% ­and 0.9-3.3%, respec­tive­ly. Overall, ­the ­strains (dila­tion) in ­the cir­cum­fe­ren­tial ­and lon­gi­tu­di­nal direc­tions ­were sim­i­lar ­before ­the throm­bus ­was ­removed.
Conclusion. Even ­though ­the throm­bus ­allows ­the trans­mis­sion of lumi­nal pres­sure to ­the aneu­rysm ­wall, it ­may pre­vent ­the aneu­rysm ­from rup­ture by dimin­ish­ing ­the ­strain on ­the ­wall. Consistent ­with ­this, a mechan­i­cal mod­el of ­the throm­bus pro­posed is “a throm­bus as a ­fibrous net­work adher­ent to ­the aneu­rysm ­wall”.