Tricuspid valve
Valva atrioventricularis dextra (valva tricuspidalis)
Also known as: right atrioventricular valve, right AV valve
The tricuspid valve is the right atrioventricular valve. Its anterior, posterior and septal cusps guard the opening between the right atrium and right ventricle.
Overview
The tricuspid valve has the largest orifice of the four heart valves; classically it admits three fingertips. Its three cusps attach to the fibrous ring and are tethered by chordae from three papillary muscles. The septal leaflet attaches slightly lower (more apically) than the anterior mitral leaflet. This offset is normal, but when it is exaggerated the condition is called Ebstein anomaly.
The valve opens during ventricular diastole, when right atrial pressure is higher than right ventricular pressure. It closes at the start of ventricular systole. Tricuspid closure (T1) follows mitral closure (M1) by a few milliseconds, and together they make the first heart sound.
- Location
Behind the right half of the sternum at about the 4th–5th intercostal spaces. It is best heard at the lower left sternal edge (4th–5th left intercostal space).
Parts & subdivisions
- Anterior cuspThe largest cusp, attached toward the front near the infundibulum.
- Posterior cuspAttached inferiorly along the diaphragmatic wall.
- Septal cuspAttached to the septum. Some of its chordae arise directly from the septal wall.
- Anterior, posterior and septal papillary muscles.
Function
- Allows blood to flow from the right atrium into the right ventricle during diastole.
- Prevents blood flowing back into the right atrium during ventricular systole.
Clinical significance
Tricuspid regurgitation
Tricuspid regurgitation is most often functional: the right ventricle and the valve ring dilate because of pulmonary hypertension or left heart disease. It produces a pansystolic murmur at the lower left sternal edge that gets louder on inspiration (Carvallo sign). There may be giant v waves in the JVP and a pulsatile liver.
Right-sided infective endocarditis
Endocarditis of the tricuspid valve is the classic pattern in people who inject drugs, usually caused by S. aureus. Fragments of the vegetations can travel to the lungs as septic emboli.
Ebstein anomaly
In Ebstein anomaly, the septal and posterior leaflets are displaced toward the apex. Part of the right ventricle then functions as atrium ("atrialised"). It is associated with lithium use in pregnancy and with Wolff–Parkinson–White syndrome.
Mnemonics
Which side is which
"Try before you buy": blood passes the tricuspid valve (right) before the bicuspid, or mitral, valve (left).
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.