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.

Varicose Veins

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.

Arteriovenous Fistulae

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 may present major treatment challenges. For instance, arteriovenous fistula of the descending aorta with the azygos vein and the superior vena cava as well as with the intercostal vessels may occur. Argon plasma laser coagulation treats skin arteriovenous fistulas successfully in most instances, with most of those occurring in the head and neck regions. These lesions are characterized by a generalized dilatation of the microscopic venous systems.

Traumatic Arteriovenous Fistula. This important but often underdiagnosed pathologic entity may be recognized by abnormal hematologic parameters (i.e., compensatory polycythemia, hemolysis, and other circulatory parameters). Doppler double-color digital imaging may settle the problem if the clinical suspicion is high. Surgical intervention will most likely result in a 100% positive clinical outcome. The majority of clinical arteriovenous fistulae are of the acquired form and result from trauma, connecting a concomitant artery and vein segment in the process of injury. During clinical examination, a bruit can be heard on auscultation. Radiolabeled red blood cells has been used successfully in the demonstration of an arteriovenous fistula. Traumatic arteriovenous fistulae can occur anywhere in the body, but the principal sites are the peripheral vascular system in the upper and lower extremities. Sclerotherapy has been of value in smaller traumatic arteriovenous fistula. Venous dilatation and fibromuscular hypertrophy may lead to venous atherosclerosis because of the increased venous pressure from the transmitted arterial pressure.

Surgical Arteriovenous Fistula for Hemodialysis. The veins in the surgically produced arteriovenous fistulas for hemodialysis undergo dilatation because of altered hemodynamics. When they are large enough for cannulation, they are defined as “mature.” Owing to increased hemodynamic pressure, the veins undergo changes, leading to atherosclerosis and fibromuscular stenosis similar to those encountered in aortocoronary bypass grafts.

Venous Aneurysms

Aneurysmal dilatation of the venous system is uncommon but may occur as a result of trauma, infection, iatrogenic or congenital causes. The thinning of the venous wall may make the pathologic area susceptible to rupture, thrombosis, and hemodynamic turbulence. Venous mycotic aneurysms are rare conditions but are important in their recognition for a successful clinical management program using surgical intervention and appropriate antibiotic coverage. The term mycotic aneurysm is misleading because it may be associated with a mycotic aneurysm of the aorta. The term mycotic does not necessarily connote a fungal disease but rather an infectious bacterial cause of the disease process. It can occur both in a downstream as well as in an upstream process with the latter less common. Both the central and the peripheral forms are essentially a result of an infected thromboembolus.

Esophageal Varices

Esophageal varices occur as a result of several causes, which are, in order of decreasing prevalence and severity: alcoholism, viral hepatitis B and C, and biliary cirrhosis. Esophageal varices caused by noncirrhotic conditions include chronic cardiac failure, thrombosis of splenic or portal vein, sarcoidosis, schistosomiasis (common in Africa, Middle Eastern Countries, Southeast Asia, the Caribbean islands, and South America), and Budd-Chiari syndrome caused by intrahepatic venous thrombosis leading to the formation of collaterals with esophageal varices.

Portal hypertension causes microvascular venous alterations such as portal hypertensive gastropathy and colopathy. In the stomach, it causes a classic endoscopic mosaic appearance producing a “snake skin”-like pattern. Microvascular alterations are characterized by microvascular aneurysms causing microscopic hemorrhage in the mucosa surfaces, including in the gastrointestinal and urogenital systems. Microscopic retinal hemorrhages may also be seen in these patients and lead to decreased vision.

The usual pathology of the veins in the various affected systems (i.e., esophageal veins and portovenous systems) show marked luminal dilatations accompanied by musculofibrous hyperplasia of the wall of the affected vessels. Dilatation of the wall causes endothelial damage and may frequently be associated with thrombosis such as in Budd-Chiari syndrome. The microscopic pathology of the microvenous system is generally characterized by diffuse venous dilatation associated with microaneurysms, microhemorrhages, and reparative neorevascularization.

Depending on the symptomatology and pathology, treatment of esophageal varices specifically and portal hypertension, in particular, involves a multitude of surgical and medical modalities, including variceal ligation (banding), sclerotherapy, balloon tamponade (Sengstaken and Blakemore tube), transjugular intrahepatic portosystemic shunt (TIPS), and open portosystemic shunts such as the distal splenorenal shunt. Treatment (especially TIPS) may lead to hepatic encephalopathy.