Trauma
to the Abdominal Aorta
Blunt trauma to the aorta is most commonly caused by headon automobile
crashes. Rupture of the tunica intima and media occurs and is quickly followed
by rupture of the turnica adventitia. The initial rupture of the intima and
media is probably mainly caused by the sudden compression of the aorta against
the vertebral column, while the delayed rupture of the adventitia is caused by
the aortic blood pressure. Unless quickly diagnosed by MRI, and surgical
treatment instituted, death follows.
Obliteration
of the Abdominal Aorta and Iliac Arteries
Gradual occlusion of the bifurcation of the abdominal aorta,
produced by atherosclerosis, results in the characteristic clinical symptoms of
pain in the legs on walking (claudication) and impotence, the latter caused by
lack of blood in the internal iliac arteries. In otherwise healthy individuals,
surgical treatment by thromboendarterectomy or a bypass graft should be
considered. Because the progress of the disease is slow, some collateral circulation
is established, but it is physiologically inadequate. However, the collateral
blood flow does prevent tissue death in both lower limbs, although skin ulcers
may occur.
Trauma
to the Inferior Vena Cava
Injuries to the inferior vena cava are commonly lethal,
despite the fact that the contained blood is under low pressure. The anatomic
inaccessibility of the vessel behind the liver, duodenum, and mesentery of the
small intestine and the blocking presence of the right costal margin make a
surgical approach difficult. Moreover, the thin wall of the vena cava makes it
prone to extensive tears.
Because of the multiple anastomoses of the tributaries of
the inferior vena cava, it is impossible in an emergency to ligate the vessel.
Most patients have venous congestion of the lower limbs.
Compression of the Inferior Vena Cava
the enlarged uterus during the later stages of pregnancy is
commonly compress The inferior vena cava. This produces edema of the ankles and
feet and temporary varicose veins. Malignant retroperitoneal tumors can cause
severe compression and eventual blockage of the inferior vena cava. This results
in the dilatation of the extensive anastomoses of the tributaries. This
alternative pathway for the blood to return to the right atrium of the heart is
commonly referred to as the caval–caval shunt. The same pathway comes into effect
in patients with a superior mediastinal tumor compressing the superior vena
cava. Clinically, the enlarged subcutaneous anastomosis between the lateral
thoracic vein, a tributary of the axillary vein; and the superficial epigastric
vein, a tributary of the femoral vein, may be seen on the thoracoabdominal wall
