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Chest Pain in Children and Adults

Mitral Regurgitation: New Concepts

Diastolic and Systolic Function

Changing the Outcome of CAD

Fig.2.30

Tricuspid regurgitation is also best evaluation from the apical window. The left parasternal right ventricular inlet view and short axis at the aortic valve level are other useful positions. In tricuspid insufficiency, systolic turbulence is detected just behind the tricuspid valve leaflets. The contour of the flow profile is very similar to that of mitral regurgitation. As with other regurgitant jets, CW Doppler is usually needed to obtain an unaliased recording of the full spectrum as seen in Figure 2.30.

We frequently detect tricuspid regurgitation by Doppler in otherwise normal individuals and find that even beginners to Doppler instrumentation will readily record this entity in between 25% and 50% of their patients. Earlier studies found a similar, frequent systolic reversal of flow in normal individuals using contrast echocardiography of the inferior vena cava. Some investigators have indicated that a small degree of tricuspid regurgitation may be seen in as many as 96% of normal volunteers by Doppler. These findings were felt to be due to true valvular tricuspid regurgitation, and not to coronary sinus systolic flow.

These findings indicate that Doppler evidence for tricuspid regurgitation is common and presents an interpretive dilemma for echocardiographers. It is clear to us that the physical findings of tricuspid regurgitation are extraordinarily insensitive and are usually seen only when the regurgitation is severe. There is no widely accepted standard method for reporting this lesion. Currently, we prefer not to report tricuspid regurgitation if it is localized just behind the tricuspid leaflets; it is only reported if the regurgitant jet can be found, by PW Doppler, to extend at least halfway between valve leaflets and posterior wall of the right atrium.

Fig.2.31

Respiratory variations are frequently observed in tricuspid insufficiency Doppler spectra, as noted in Figure 2.31, and may be occasionally used to distinguish between mitral and tricuspid insufficiency when using the blind CW Doppler approach. They result from differential volume filling into the right atrium and ventricle during respiratory cycle. During inspiration, right ventricular filling is augmented due to a fall in intrathoracic pressure.

Fig.2.32

A tricuspid regurgitant jet may be used to estimate right ventricular systolic pressure (RVSP) in mmHg. This method, like all Doppler pressure estimates, is based on the modified Bernoulli equation (dp=4V²) discussed in Unit 1. Figure 2.32 shows the rationale for this calculation based upon idealized pressure tracings. When normal RVSPs are encountered and tricuspid regurgitation is present, only small pressure gradients occur and low velocity spectral recordings would be anticipated. When high RVSPs are encountered and tricuspid regurgitation is present, much higher systolic gradients exist between the right ventricle and right atrium in systole. Thus, much higher velocity spectral recordings would be anticipated.

Fig.2.33

It must be understood that the pressure within the right atrium exerts a significant effect on the peak systolic velocity of tricuspid regurgitation. Figure 2.33 demonstrates this influence and shows the importance of estimating the pressure within the right atrium before attempting these calculations. For any given systolic pressure in the right ventricle, a low pressure in the right atrium would result in a higher gradient between atrium and ventricle and, therefore, a higher velocity than when a high right atrial pressure exists. In the latter case, the higher right atrial pressure reduces the gradient and, therefore, the resultant velocity of the tricuspid regurgitation jet.

The right atrial pressure may be estimated by examination of the patient's neck veins. Using this method, mean jugular venous pressure (JVP) in cmH₂0 is first estimated by inspection of the jugular venous pulse with the patient at 45 degrees. Right atrial pressure (RAP) is estimated by adding 5 cm to the venous pressure measurement (to approximate the distance between the right atrium and the clavicle) and then converted to mmHg by dividing by 1.3. This is then added to the trans-tricuspid systolic gradient estimated from the peak tricuspid velocity. The formula is:

RVSP=
(JVP+5/1.3)+(peak systolic velocity²x4)

The patient pictured in Figure 2.30 has a peak systolic velocity of 2.4 m/sec that is equivalent to a peak trans-tricuspid systolic gradient of 23mmHg. Since the jugular venous pulse was estimated at 15 cm, the right atrial pressure would be 20 cmH₂0 (=15mmHg). Using the above equation, we would predict a right ventricular systolic pressure of 38mmHg.

Doppler catheterization correlations for measurement of RVSP have been reported as being very accurate, and practical application of these methods in our laboratory supports the reliability of this approach. When pulmonary stenosis does not exist, peak RVSP should reflect peak systolic pulmonary artery pressure.

Fig.2.34

Thus, many factors influence the peak velocity and appearance of the spectral tricuspid regurgitant jet. A demonstration of these differences is seen in Figure 2.34 where one patient has a high velocity jet measuring 6 m/sec (left panel) and another has a systolic jet measuring 3 m/sec (right panel). If both patients had 5 cm of neck vein distension, the patient on the left would have a predicted peak RVSP of 152 mmHg and the one on the right would have a predicted peak RVSP of 44mmHg.

Fig.2.35

Arrhythmias will also profoundly affect the contour and peak velocities noted. A CW Doppler recording of tricuspid regurgitation from a patient with atrial fibrillation is seen in
Figure 2.35. Note the differing velocities with the irregular rhythm.

 

 

 

 

Fig.2.36

As with the left-sided valves, there are reasons for the detection of false positive and false negative results that are similar to those previously discussed. One interesting cause of a false positive diagnosis is excessive upward angulation of the interrogating beam that thus intercepts aortic, rather than tricuspid flow (Fig. 2.36). The left panel shows the assumed proper orientation of the CW beam while the center panel shows the actual superior angulation with the beam intercepting eh aortic root. The right panel shows the superior plane superimposed on the assumed plane when this error occurs. This is of particular importance in patients with aortic stenosis when higher velocity jets will be seen in the aorta.

Other reasons for a false positive diagnosis include confusion with mitral regurgitation or with valve slap as discussed previously. False negatives may occur due to small jets missed by inadequate examinations, moving jets, or intermittent jets due to the respiratory cycle.

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