The peripheral and internal venous system is a huge vascular bed responsible for returning both deoxygenated peripheral blood and detoxified internal blood by the liver back to the general circulation via the superior and inferior vena cava. The huge anatomical extent of this system exposes it to a multitude of factors that may induce a magnitude of anatomical changes producing life-threatening complications, such as ruptured esophageal varices.
In contrast to the arterial system, the venous system is characterized in general by thin pliable walls because of its reduced fibromuscular and elastic mural component (Figure 2-1A). This unique characteristic of the venous system with associated low venous pressure conditions essentially precludes it from developing atherosclerosis.
(A) Microscopic normal vein (100x). (B) Post-aortocoronary vein graft with thrombosis. (C) Vein graft with fresh postoperative thrombosis (100x). (D) Vein graft segment with postoperative thrombophlebitis (100x).
MAJOR PERIPHERAL VEIN PATHOLOGIES
Varicose veins are very common, with a high male-to-female discrepancy and essentially conditioned by stasis or obstruction of the proximal segment of the vein system. In addition to stasis as a causative feature leading to varicosity, the competency of the vein valves is certainly another important factor in the development of varicose veins as are hereditary factors. Intraabdominal pressure of any cause (e.g., pregnancy, intraabdominal masses, cysts, tumors, aneurysms) may cause venous return flow problems and therefore contribute to varicosity concerns. Thrombophlebitis of any cause is also important in the development of varicose vein complications. Migratory phlebitis associated with internal malignancies, such as pancreatic carcinoma, is of specific interest because phlebitis may serve as a red flag and raise the suspicion of an underlying malignancy. This combination of migratory phlebitis with underlying malignancy is also referred to as Trousseau syndrome. The incidence of thromboembolism is very low with this entity compared with deep venous thrombosis (DVT) evolving from the deep venous system. Cardiovascular problems, such as valve disease, coronary arteriosclerosis, cardiomyopathy, viral and infectious diseases, as well as systemic metabolic problems such as uremia with subsequent uremic pericarditis, can lead to an on-and-off congestive heart failure with its deleterious impact on the peripheral and internal vein system. Pathologic findings include dilatation and fibromuscular hypertrophy leading to endothelial tears and subsequent wall damage and possible thrombosis.
Congenital Arteriovenous Fistula. These occur predominately in the skin, stomach, and colon and can be recognized early in an infant's life. Large congenital arteriovenous fistulas involving major vascular channels do occur as well and ...