Tricuspid regurgitation (TR) is a valvular cardiac anomaly where there is regurgitation of flow from the right ventricle back into the right atrium through the tricuspid valve. It is considered an important predictor of both morbidity and mortality in heart failure 8.
Clinical features can vary dependent of the severely of regurgitation from being entirely asymptomatic in mild cases to having several classical signs such as:
Primary tricuspid regurgitation in isolation is very rare. It is more often found in association other valvular disease (more often with mitral rather than with aortic valve disease).
In a majority of patients (70-85%), the TR is considered “functional” 12, where it is caused by dilatation of the annulus as a result of increased pulmonary and right ventricular pressures; in the remaining 15–30% , it may be organic and related to direct involvement of the tricuspid valve.
A major haemodynamic consequence of tricuspid regurgitation is an increase in the total stroke volume of the right ventricle.
Tricuspid regurgitation can result from number of causes such as:
- congenital abnormalities (e.g. Ebstein anomaly)
- dilatation of the right ventricle and/or the tricuspid annulus
- as a late complication following mitral valve surgery 11
- direct factors affecting the valve
- Marfan syndrome
- phentermine +/- fenfluramine use 10
Ultrasound - echocardiography
This is probably the most traditional best used methods of detection and assessment. It may be best evaluated from the apical window. Left parasternal, right ventricular inlet view and short axis at the aortic valve level may be other useful positions.
In TR, systolic turbulence may be detected just behind the tricuspid valve leaflets. The flow contour profile can be very similar to that seen with mitral regurgitation.
The shape of the tricuspid annulus can alter with regurgitation. A normal annulus has a bimodal shape with distinct high points located anteroposteriorly and low points located mediolaterally. With functional tricuspid regurgitation, the annulus can become larger, more planar, and circular 8.
On spin-echo MR images, features that may be visible which could suggest towards a diagnosis of TR include:
- enlargement of the right ventricle
- enlargement of the right atrium
- distension of the vena cavae and hepatic veins
Cine gradient-echo imaging can be used to evaluate tricuspid regurgitation based on the area of the signal void corresponding to the regurgitant flow jet in systole. The signal void is best demonstrated on a four-chamber view and a coronal oblique view encompassing the right atrium and the right ventricle.
The degree of tricuspid regurgitation may be calculated in terms of regurgitant volume and fraction in similar ways to mitral regurgitation - i.e. subtraction of the forward stroke volume (as measured in the pulmonary artery with phase contrast) from the total right ventricular stroke volume (obtained from SSFP images).
Enlargement of the right atrium and right ventricle may also be seen on standard as well as cardiac CT.
Dynamic contrast enhanced abdominal computed tomography (CT) may show intense opacification of the inferior vena cava and hepatic veins.
Treatment and prognosis
Typically treated medically with diuretics to reduce blood volume.
If the valve is replaced it is usually performed at the same time that other cardiac valves are replaced (since these patients frequently have multiple cardiac valve abnormalities). Indications and timing for sole replacement of the tricupid valve are not well established.
Complications of untreated tricupsid regurgitation:
- tricuspid regurgitation is a common (~70%) incidental finding on echocardiography and cardiac MRI; it should be considered physiological if 13:
- the size of the RA and RV are normal
- the jet extends <0.7 cm into the RA
- hepatic vein pulsatility is normal
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