Echocardiography of the Right Ventricle and Tricuspid Valve:
©Walter Rasmussen, R.D.C.S.
From the apical 4-Chamber view, the right heart is usually fairly easy to image. The hallmarks of this view are visualization of the right atrium, tricuspid valve and the right ventricular chamber and RV free wall from base to apex. It can sometimes be extremely difficult to image the entire right ventricular free wall however, right ventricular function cannot be fully assessed without a clear image.
The clarity of the left ventricle is of lessor importance while concentrating on the right side of the heart. It may be necessary to tilt the transducer medially in order to bring the right side of the heart into better view. Gain, dynamic range, transducer frequency, and focal zone should be customized as necessary, for the best quality image.
Breathing maneuvers such as some degree of inhalation with breath held can make a dramatic improvement in the image of the right side of the heart from the apical window. If tilting of the transducer and breathing maneuvers do not improve the image, it can be helpful to slide the transducer medially toward the sternum and if necessary, up one intercostal space so that the right ventricular apex is visualized at the peak of the sector, as illustrated below.
- Visual inspection of the right ventricle, right ventricular free wall, tricuspid valve and right atrial structures, including implanted catheters, pacemaker leads, and ASD closure devices.
- Color Doppler assessment of the degree of tricuspid regurgitation and ASD or VSD jets.
- CW Doppler recording of the peak tricuspid regurgitation velocity.
- M-Mode of the tricuspid annular plane systolic excursion (TAPSE).
- PW Doppler of tricuspid inflow for tricuspid stenosis and for assessment of the fo pericardial constriction.
For the assessment of suspected endocarditis, thorough examination of the tricuspid valve is important. The chaotic movement of the vegetation can be better assessed when several cardiac cycles are recorded. Higher transducer frequencies increase the diagnostic capabilities for the detection of endocarditis because vegetations may be small or very delicate in structure.
Tricuspid Annular Plane Systolic Excursion (TAPSE):
TAPSE (tricuspid annular plane systolic excursion), is a technique in which the M-Mode cursor is placed at the anterior tricuspid valve annulus and a strip chart recording made of its movement with each cardiac cycle. It is important to try to position the transducer so that the M-Mode cursor is better-aligned with the movement of the tricuspid annulus. For instances when the M-Mode cursor is not well aligned, Anatomic M-Mode can be used for more accurate assessment.
After freezing the image, a distance measurement is made with the slope caliper. This imaging technique is used primarily for the assessment of right ventricular function and grading the severity of pulmonary hypertension and left heart failure.
Color Doppler of the Right Heart:
It can be extremely difficult to image mild or physioloic amounts of tricuspid regurgitation however, meticulous effort should be made because visualization of the jet makes possible the important CW Doppler recording of the actual jet velocity.
After the two-dimensional image of the right ventricle and right atrium is recorded, color Doppler is used to assess for tricuspid regurgitation. Place the Color Box over the tricuspid valve and search for the TR jet by tilting the transducer in all directions. If TR is present, adjust the size as needed to capture its full length and width.
For maximum sensitivity, adjust the Color Doppler gain to just beneath the appearance of noise which is represented by brief, random pixelations. The Color Doppler scale should be set at 50-60 cm/sec so that the jet area is not diminished or exaggerated by a higher or lower setting or excessive Color Smoothing. Once Color Doppler has established the TR jet area, use CW Doppler to assess its actual velocity .
CW Doppler of the Tricuspid Valve:
An estimation of the pressure gradient between the right ventricle and right atrium derived from CW Doppler of the peak tricuspid regurgitant jet velocity is a core element of the routine echocardiogram and it is of particular importance for patients with pulmonary hypertension and heart failure.
If the TR jet is easily found on Color Doppler, then obtaining a TR velocity with CW Doppler is not likely to be difficult. In order to provide the maximum Doppler shift the transducer should be placed so that the CW Doppler cursor can be aligned as closely as possible to the axis of the jet from its origin at the leaflet tips. If the TR jet is difficult to locate, the patient can be directed to suspend respiration where the greatest image clarity is obtained while the best possible TR jet is located and recorded. Another respiratory technique requires fixing the CW cursor at the point where respiration brings the TR into alignment with the cursor and then have the patient do one cycle of inhalation and exhalation at a time until by trial and re-positioning, a full TR jet is obtained. Caution should be taken in using active repeated respirations because the patient might hyperventilate.
An incomplete TR jet as shown here, is of limited diagnostic value and because of the importance of obtaining a good recording even for routine echocardiograms, the sonographer should pay more than just cursory attention to the task. Making just slight changes to the transducer position, angle and rotation can make the difference between success and failure.
If the imaging probe cannot produce an adequate TR velocity profile, rather than moving directly to using a saline injection, the Pedoff probe may yield a better recording. An experienced sonographer who has mastered the use of the Pedoff probe is able to navigate between the mitral, aortic and tricuspid valves with a fair amount of confidence even though it lacks a reference two-dimensional image. See the section dedicated to the Pedoff transducer for more information.
The apical four chamber view is considered the primary window for obtaining the best alignment with the tricuspid regurgitation jet however, alternate views including the subcostal four chamber, the parasternal RVIT or the parasternal SAX, may yield better cursor alignment, better Color Doppler images and higher velocities, dependent on the axis of the jet. The above-mentioned alternate views should always be recorded if they yield any TR jet information. It is important to remember that the peak velocity can be easily under-estimated and even if it is only possible to record portions of the TR jet, the limited information can still be useful for diagnostic purposes.
The adjustment of dynamic range and Doppler gain can be very useful for improving the definition of the edge of the spectral Doppler envelope. If the edge of the spectral Doppler recording is too soft, inaccurate measurements can result. Colorization of the spectral Doppler recording can greatly enhance visual perception of a weak signal.
PW Doppler of the Tricuspid Valve
Pulsed-wave Doppler of the tricuspid valve is performed for the assessment of diastolic blood flow. This is pirmarily useful for suspected tricuspid stenosis and for the detection of right ventricular constriction during pericardial tamponade.
Diastolic blood flow pattern across the tricuspid valve varies with respiration.
The pulsed Doppler techniques for the tricuspid valve are identical to those used for the mitral valve. Assessment of peak and mean tricuspid valve diastolic flow, pressure half-time and respiratory variation of blood flow can all be assessed with pulsed Doppler.