Jugular venous pressure

The jugular venous pressure (JVP, sometimes referred to as jugular venous pulse) is the indirectly observed pressure over the venous system. It can be useful is the differentiation of different forms of heartand lung disease.

Method

A classical method for quantifying the JVP was described by Borst & Molhuysen in 1952. It has since been modified in various ways.

The patient is positioned under 45°, and the filling level of the jugular veindetermined. In healthy people, it is maximum several (3-4) centimetresabove the sternalangle. Some doctors employ a venous arc, an instrument to measure the JVP more accurately. A pen-light can aid in discerning the jugular filling level.

The JVP is elevated in venous hypertension (e.g. right-sided heart failure) and paradoxically increased in Kussmaul's sign(see there).

The hepatojugular reflex is an expanded form of the JVP measurement. By pressing on the liver(hepato-) for 15-30 seconds, venous blood is advanced into the circulation. The JVP increases in a normal person. However, a slow decrease of the JVP after checking the hepatojugular reflex can indicate right ventricular failure.

Causes of an elevated JVP include:

• Bradycardia
• Constrictive pericarditis
• Fluid overload (intravenousfluid)
• Right heart failure
• Hyperdynamic circulation (e.g. in extreme anemia)
• Obstruction of the superior vena cava
• Pericardial effusion
• Tricuspid valvedisease (stenosis or regurgitation)

Differentiation of the JVP from the carotid pulse

Pulsesin the JVP are rather hard to observe, but trained cardiologists do try to discern these as signs of the state of the right atrium.

The JVP and carotid pulse can be differentiated several ways:

• multiphasic - the JVP "beats" twice (in quick succession) in the cardiac cycle. In other words, there are two waves in the JVP for each contraction-relaxation cycle by the heart. The first beat represents that atrial contraction (termed a) and second beat the ventricular contraction (termed v). The carotid artery only has one beat in the cardiac cycle.
• non-palpable - the JVP cannot be palpated. If one feels a pulse in the neck, it is generally the common carotid artery.
• occludable - the JVP can be stopped by occluding the internal jugular veinby lightly pressing against the neck.
• varies with head-up-tilt (HUT) - the JVP varies with the angle of neck. If a person is standing their JVP appears to be lower on the neck (or may not be seen at all because it below the sternal angle). The carotid pulse's location does not vary with HUT.
• varies with respiration - the JVP usually descreases with deep inspiration. Physiologically, this is a consequence of the Frank-Starling mechanismas inspiration decreases the thoracic pressure and increases blood movement into the heart (venous return), which a healthy heart moves into the pulmonary circulation.
• abdominal jugular reflex (AJR) (also hepatojugular reflex) - the JVP changes with abdominal pressure. If the JVP is elevated 4 cm, it usually returns to its baseline level within 10 seconds. If the JVP remains elevated for a longer period of time it suggests heart failure.

The JVP is easier to observe if one looks along the surface of the sternocleidomastoid muscle; it is easier to appreciate the movement relative the neck when looking from the side, as opposed to looking at the surface at a 90 degree angle. (Analogy - judging the movement of automobiles: it is easier to see the movement of an automobile when it is crossing one's path (at 90 degrees - i.e. moving left to right or right to left), as opposed to coming toward one). Interpretation of JVP findings can be challenging. Some classics are "cannon a-waves" (when the atrium contracts with the tricuspid valve still closed, e.g. due to arrhythmia).

Reference

• Borst JG, Molhuysen JA. Exact determination of the central venous pressure by a simple clinical method. Lancet 1952;2(7):304-9. PMID 14955978.

External links

• Clinical Examinationpage on JVP
• JVP- may not be very useful

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Jugular+venous+pressure Wikipedia article Jugular venous pressure.