The v wave rise in the RA pressure in the absence of significant tricuspid regurgitation is almost always a result of venous filling of the right atrium in the later part of systole whether the actual pressure is normal or high. The normal right atrium, being a capacitance chamber, has good distensibility. The venous inflow from the venae cavae augmented by the x' descent tends to build up a pressure that is often quite low, not exceeding 5 mmHg. In children the circulation is rapid because of high sympathetic tone, and the rapid venous inflow coming into an atrium, which is relatively small, could build up a relatively good v wave pressure. Rapid circulatory states with high sympathetic tone may also exist in conditions such as pregnancy, thyrotoxicosis, and anemia (19), which also favor buildup of relatively high v waves. In pregnancy, in addition, the blood volume is usually expanded. Hypervolemia, however, could raise the v wave pressure. Occasionally in some patients with atrial septal defect, the extra source of venous return from the left atrium across the defect together with some changes in RA distensibility could also lead to a higher than normal v wave pressure (14,17,24).
Because the pre-a wave pressure sets the baseline over which the a wave and v wave buildups naturally occur, the most common reason for pathologically high v wave pressure is an elevated high pre-a wave pressure. The reasons for this, discussed previously, include conditions such as pericardial effusion with any degree of restriction, constrictive pericarditis, pulmonary hypertension with elevated RV diastolic pressure, ischemia, and/or infarcted right ventricle and cardiomyopathy. For any given degree of elevation of pre-a wave pressure and right atrial distensibility, any rise in venous tone (sympathetic tone) will allow a much further rise in the jugular v wave.
In the jugulars, the v wave can be inferred to be present whenever a y descent is recognized. The v wave is the wave preceding the y descent, which can be timed to be diastolic. Normal v wave is not usually seen in the jugulars in the adult, as recognized by the fact that the y descent is absent. The rise of even an abnormal and elevated v wave (e.g., heart failure, constrictive pericarditis) is not usually as prominent to the observer's eyes as the fall of the y descent that follows it. The reason for this is an absence of any flow reversal in the jugulars under these conditions. This is in contrast to the v wave of tricuspid regurgitation, which always causes systolic flow reversal (40) (Figs. 11 and 7G) (see JVP Videofiles 5-7 and 9 in Abnormal Jugular Contours on the Companion CD).
The v waves have a larger duration and, therefore, when elevated are associated with higher mean right atrial pressure. Normally on inspiration the intrathoracic pressure falls, leading to an increase in the venous return. The right atrium, being an intrathoracic structure, is also influenced by the fall in intrathoracic pressure. In addition, the capacitance function of the right heart accommodates for the increased venous return without a rise in the RA pressure. In fact, inspiration leads to a fall in the RA pressure reflecting the fall in intrathoracic pressure. However, sometimes the RA and therefore the jugular venous pressure may actually rise with inspiration. This is termed the Kussmaul's sign (20,21,51). This sign may be identified by the fact that the v wave is more prominent during inspiration. The latter may be recognized by the inspiratory augmentation of the y descent. The Kussmaul's sign is generally indicative of decreased compliance of the right heart and/or its surrounding structures. Thus, it may be seen in a variety of conditions including heart failure, restrictive pericardial pathology with or without effusion, and occasionally thoracic deformities such as kyphoscoliosis.
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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...