Ultrasound Technique to Detect Internal Jugular Valve Incompetence and Clinical Implications

Abstract

The internal jugular ( IJ) valves are absent in 6% to 13%, more commonly in the left-sided than the right-sided veins, and typically bicuspid valves ( 66%), but can be unicuspid (15%), tricuspid (6%), or absent (13%). They are located at an approximately 0.3-0.5 cm above the junction with the brachiocephalic vein, but the position in the neck or chest can vary from being almost directly posterior, to 3 cm inferior and lateral, to the head of the clavicle. The closure of the IJ valve occurs during diastole when the atrium transmits backward pressure from the right atrium into the superior vena cava, then into the IJ vein. The competency of the IJ valves has been previously tested by IJ venography during Valsalva maneuver or cough, a Doppler sample of the IJ vein flow combined with M-mode ultrasonography of the IJ valve during Valsalva, the color flow imaging (CFI) of the IJ vein. However, IJ venography is invasive, while it is difficult to interpret duplex and CFI data of the IJ vein due to slow and swirling flow in IJ vein. We have introduced the use of air contrast ultrasonography with B-mode imaging during Valsalva, so called the air contrast ultrasound venography (ACUV). The ACUV provides rapid, reliable, practical, and noninvasive, method for detection of absent or incompetent IJ valves. In addition the ACUV is more sensitive to assess IJ valve incompetence due to well visualized of the air contrast bubbles from the IJ venous reflux. The IJ veins are the principle route of venous drainage of the brain through cerebral vein emptying into the dural venous sinuses, then into the IJ veins. The IJ valve is the only valve between the heart and the brain, preventing venous reflux into the IJ vein. Uni-or bilateral IJ valve incompetence prevalence ranges from 29% in the young adult population to 33-45% in healthy elderly subjects. However, the IJ valve incompetence with IJ vein reflux has been found more frequently in several neurological diseases such as transient global amnesia, transient monocular blindness, cough headache, primary exertional headache and in some medical conditions such as elevated central venous pressure, congestive heart disease, tricuspid valve regurgitation, primary pulmonary hypertension, chronic obstructive pulmonary disease, prolong positive end-expiratory pressure ventilators and status post IJ vein cannulation, probably resulting from cerebral venous outflow impairment. Thus, the incompetent IJ valves leading to cerebral venous hypertension might play a major role in the mechanism of these neurological disorders.