Aortoiliac hemodynamic and morphologic adaptation to chronic spinal cord injury.
BACKGROUND
Reduced lower limb blood flow and resistive hemodynamic conditions potentially promote aortic inflammation and aneurysmal degeneration. We used abdominal ultrasonography, magnetic resonance imaging, and computational flow modeling to determine the relationship between reduced infrarenal aortic blood flow in chronic spinal cord injury (SCI) subjects and risk for abdominal aortic aneurysm (AAA) disease.


METHODS
Aortic diameter in consecutive SCI subjects (n = 123) was determined via transabdominal ultrasonography. Aortic anatomic and physiologic data were acquired via magnetic resonance angiography (MRA; n = 5) and cine phase-contrast magnetic resonance flow imaging (n = 4) from SCI subjects whose aortic diameter was less than 3.0 cm by ultrasonography. Computational flow models were constructed from magnetic resonance data sets. Results were compared with those obtained from ambulatory control subjects (ultrasonography, n = 129; MRA/phase-contrast magnetic resonance flow imaging, n = 6) who were recruited at random from a larger pool of risk factor-matched individuals without known AAA disease.


RESULTS
Age, sex distribution, and smoking histories were comparable between the SCI and control groups. In the SCI group, time since injury averaged 26 +/- 13 years (mean +/- SD). Aortic diameter was larger (P < .01), and the prevalence of large (> or = 2.5 cm; P < .01) or aneurysmal (> or = 3.0 cm; P < .05) aortas was greater in SCI subjects. Paradoxically, common iliac artery diameters were reduced in SCI subjects (< 1.0 cm; 48% SCI vs 26% control; P < .0001). Focal preaneurysmal enlargement was noted in four of five SCI subjects by MRA. Flow modeling revealed normal flow volume, biphasic and reduced oscillatory flow, slower pressure decay, and reduced wall shear stress in the SCI infrarenal aorta.


CONCLUSIONS
Characteristic aortoiliac hemodynamic and morphologic adaptations occur in response to chronic SCI. Slower aortic pressure decay and reduced wall shear stress after SCI may contribute to mural degeneration, enlargement, and an increased prevalence of AAA disease.
Yeung
Janice J
JJ
Department of Surgery, University of Rochester, Rochester, NY, USA.
Kim
Hyun Jin
HJ
Abbruzzese
Thomas A
TA
Vignon-Clementel
Irene E
IE
Draney-Blomme
Mary T
MT
Yeung
Kay K
KK
Perkash
Inder
I
Herfkens
Robert J
RJ
Taylor
Charles A
CA
Dalman
Ronald L
RL
D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001794:Blood Pressure; D016022:Case-Control Studies; D002574:Cervical Vertebrae; D002908:Chronic Disease; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007083:Iliac Artery / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D008159:Lumbar Vertebrae; D018810:Magnetic Resonance Angiography; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011673:Pulsatile Flow; D012039:Regional Blood Flow; D012307:Risk Factors; D013119:Spinal Cord Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D013314:Stress, Mechanical; D013904:Thoracic Vertebrae; D013997:Time Factors; D014463:Ultrasonography; D014481:United States; D014728:Veterans