What is the most common cause of JVD?

Jugular vein distension (JVD) is most commonly associated with chronic hypoxemia and right heart failure. JVD occurs when there is increased pressure in the right atrium, which can result from a variety of cardiac conditions, but right heart failure is a primary cause. When the right side of the heart is unable to pump blood effectively, it leads to a backlog of blood in the large veins that return blood to the heart, causing the jugular veins to become distended as pressure rises. Chronic hypoxemia can contribute to heart failure by affecting the heart's ability to function efficiently due to prolonged low oxygen levels, further compounding the issue of JVD.