Venous distension occurs when the veins swell because there is a greater volume of blood moving through them than there should be. There are a number of reasons that the veins and arteries can distend, and one of the more serious causes is heart disease. Doctors often observe the jugular vein in a patient's neck as a part of the process of diagnosing this disease. If the vein appears swollen, this is a strong indicator that the blood pressure is too high and that the heart is not functioning normally.
Though the veins are designed to carry a certain, optimal volume of blood through the body, the presence of more or less blood will cause the veins to expand or contract accordingly. When there is more blood than usual, a patient may experience venous distension. The volume of blood fluctuates under normal circumstances, so a slight swelling of the veins may not be cause for alarm. When large veins distend noticeably, however, it can be a symptom of disease.
Patients with congestive heart failure often have venous distension. In this condition, blood flow throughout the body is compromised because the heart is unable to pump enough blood through the blood vessels. When the kidneys do not come into contact with enough blood, they retain salt as a way to pull more fluid into the bloodstream, increasing the volume of blood and, under normal circumstances, correcting the problem of inadequate blood flow. Unfortunately, in patients with congestive heart failure, the retention of additional salt makes the problem worse because it causes distension of the veins.
When the veins are swollen, the blood pressure of the patient is higher than it should be. Blood pressure is the pressure that blood places on the walls of the veins and arteries and is naturally higher if there is so much blood moving through these vessels that the walls must expand to accommodate it. Venous distension can stress the walls of the veins, leading to ruptures that could kill or seriously injure a patient.
Most veins are buried deep within the body, making it difficult for doctors to observe venous distension. The jugular vein in the neck, however, is a large vein that lies close to the surface of the skin. When this vein is distended, it can appear to be swollen. A doctor can observe blood flow through this vein in order to approximate the pressure on the walls. If jugular distension is severe, it can be a strong indicator that a patient has heart failure.