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Dr. Vittorio Dall'Aglio - Medico Chirurgo specialista in Cardiologia - Pordenone
 

Doppler assessment of the right atrio-ventricular valve


NICOLOSI G.L., DALL’AGLIO V., BITTO S., BRIEDA M., BUDANO L., D’ANGELO G., LESTUZZI C., MIMO R.,
MORO E., PAVAN D., PIGNONI P., ZANUTTINI D.

Cardiologia, Ospedale Civile, Via Montereale 24, 33170 Pordenone (.Italy)


© 1988 Elsevier Science Publishers B.V. (Biomedical Division)
Echocardiography 1988
A. Dagianti and H. Feigenbaum, editors

INTRODUCTION

Doppler echocardiography allows to obtain detailed information on flow velocity profiles of the tricuspid valve. Pulsed Doppler, continuous-wave Doppler and color Doppler offar different complementary modalities of exploring right atrio-ventri-cular inflow [1-4]. Multiple tomographic planes from different approaches are necessary to provide the most complete evaluation of the tricuspid valve inflow,due to the complex three-dimensional geometry of the valve itself,of the related atrial and ventricular chambers and, consequently, of the intracavitary flow profiles. Long axis,short axis, four-chamber and a11 intermediate off-axis views, which can be needed for the complete diagnostic evaluation, should be searched from the left and right parasternal, apical, subcostal and suprasternal approaches, both for imaging and Doppler interrogation. This procedure should allow the examiner to identify different sources of Intracavitary flow inside the right chambers,to obtain the optimal alignment with flow itself, and to differentiate right atrio-ventricular valve inflow from,for example, normal systemic venous return, coronary sinus drainage,septal defects, pulmonary valve leakage,fistulous drainage and so on [1-3].

NORMAL TRICUSPID INFLOW

Normal tricuspid inflow velocity profile resembles mitral flow,except that flow through the tricuspid valve shows major changes during respiration.The diastolic curve has two peaks,the first during early rapid filling and the second during atrial contraction. The first peak usually ranges from 30 to 70 cm/sec (average 50 cm/sec). The second peak averages 30 en/see. Even normal respiration can induce variations of flaw velocity by as much as 20 cm/sec [3].

TRICUSPID STENOSIS

Tricuspid stenosis [1-9] usually coexists with mitral stenosis,and often is associated to some degree of tricuspid regurgitation. Tricuspid stenosis can be usually diagnosed from two dimensional echocardiographic images. From Doppler recordings of tricuspid diastolic flow, however, transtricuspid gradient and tricuspid valve area can be calculated. Color Doppler is helpful to visualize directly the transtricuspid jet, with increased brightness,color reversal and mosaic pattern,due to aliasing and turbolence. Direct visualization of the jet and the audio Signal are very helpful to achieve the optimal alignment between the ultrasonic beam of continuous-wave Doppler and the Stenotic jet. From the increased diastolic velocities,by using the simplified Bernoulli equation
( A P = 4V2 ),the transtricuspid gradient can be derived.The severity of tricuspid stenosis may be assessed by calculating the peak transvalvular gradient, the mean gradient, or by measuring the pressure half-time,as it has been described for mitral stenosis (Figure 1).

Fig. 1. Continuous-wave Doppler tracing in a case of tricuspid stenosis with associated regurgitation. Peak transvalvular diastolic velocity is 1.1 m/sec, suggesting a peak transvalvular gradient around 5 mmHg. Pressure half-time is equal to 160 msec. The derived estimated area is then around 1.4 sq.cm. Tricuspid insufficiency is also seen in systole with a peak velocity around 2 m/sec. This is consistent with normal pulmonary artery pressure in this patient with associated mitral valve disease. A slight beat to beat variation of peak systolic regurgitation velocity is also seen in this case.

TRICUSPID REGURGITATION

Doppler echocardiography is a very sensitive technique for the evaluation of tricuspid regurgitation [1-4,9-15] (Figure 1 and 2). Color Doppler is the most
easy and rapid approach in this field (Figure 2). Trivial tricuspid regurgitation is not uncommon in otherwise normal subjects: this should not be considered a pathologic finding. Color Doppler is very useful to define the origin of the jet inside the architecture of the valve, to follow the orientation of the jet, to evaluate the: extension at the disturbed flow inside the right atrial cavity, to facilitate the alignment ef continuous-wave Doppler. There is a large variability as far as origin of the jet (central or eccentric ar from multiple leaks), orientation of the jet (along the inter-atrial septum, centrally, laterally or inferiorly oriented) (Figure 2).

Fig. 2. Black and white reproduction of a stop-frame of a color flow display in a case of moderate tricuspid regurgitation. This is a modified four-chamber view for the visualization of the right ventricle (RV) and right atrium (PA).Both cavities are enlarged. Arrows inside the right atrium are indicating the lateral borders of the jet of tricuspid regurgitation (with turquoise appearance and central mosaic pattern in the color display).The regurgitant jet has central origin from the valve with lateral and posterior orientation.

The severity of tricuspid regurgitation can be graded in a manner similar to that used for mitral regurgitation. We currently use three grades of severity, i.e mild, moderate or severe,in relation to the extent of cross-sectional area of the right atrium which is filled by the disturbed flow (Figure 2). The major problem has been,however, that there is no standard reference for quantitating tricuspid regurgitation, either at the bed side, in the catheterization laboratory, or in the operating room, for reliable comparison. An other problem can be the variation induced on tricuspid regurgitation by respiration, arrhythmias or different therapeutic approaches. The extension and direction of the Jet can also .change during the same cardiac cycle, as documented by frame by frame analysis. It must be also taken into account that Doppler echocardiography is a technique to detect flow velocity, and the relation between flow velocity and volume of flow (or regurgitant volume) is neither easy to be defined nor univocal.

Tricuspid regurgitation can also be assessed by examining venous flow in the hepatic veins from a subcostal approach. In patients with no or mild tricuspid regurgitation, normal hepatic venous flow can be observed.This is characterized by slight anterograde flow (towards the right atrium) during ventricular systole, followed by rapid anterograde flow during diastole.As severity of tricuspid regurgitation increases, the hepatic vein flow velocity tracing may show retrograde or positive flow during systole, produced by the regurgitant stream.
The right ventricular systolic pressure, and thereby the pulmonary systolic pressure,may be estimated by applying the simplified Bernoulli equation to the measured peak velocity of tricuspid regurgitant jet (by continuous-wave Doppler), and adding the clinically estimated right atrial pressure (Figure 1). Color Doppler may improve this approach by facilitating optimal alignment of the conventional Doppler beam with the regurgitant jet.

DIFFERENTIAL DIAGNOSIS

Doppler echocardiography can also be used for the differential diagnosis between tricuspid insufficiency and left ventricular to right atrium communication, in the follow-up of patients with carcinoid tumors (in order to detect the appearance and the progression of valvular involvement) in the follow-up of subjects with congenital heart disease and involvement, of the right atrio-ventricular valve, in the assessment of prosthetic valve dysfunction or perivalvular leaks, in the evaluation of the results of surgical reconstruction of diseased tricuspid valve.

CONCLUSIONS

Doppler echocardiography is in fact a very useful and sensitive technique to detect flow abnormalities of the right atrio-ventricular valve.The high sensitivity of the technique allows often to identify flow abnormalities of the tricuspid valve even before, or in absence, of morphologic changes of the valve itself or of the related atrial and ventricular chambers. For this reason those abnormalities should be interpreted taking into account the sensitivity of Doppler technique and clinical and hemodynamic findings of each subject. This can be of particular relevance in the process of clinical decision making at the bed aide of the patient.

REFERENCES

1. Hatia L, Angelsen B (1985) Doppler ultrasound in Cardiology. Second Edition, Lea and Febiger; Philadelphia
2. Nanda NC (1985) Doppler echocardiography. Igaku-Shoin, New York-Tokyo
3. Adhar GC, Nanda NC (1984) Doppler echocardiography:Part II:Adult valvular heart disease. Echocardiography 1:219-241
4. Omoto R (1987) Color atlas of real-time two-dimensional Doppler echocardiography. Shindan-To-Chiryo Co., Tokyo
5. Skelton TN, Kisslo J (1985) Real-time Doppler color flow mapping in stenotic Valvular lesions. Echocardiography 2:523-531
6. Richards KL (1987) Doppler echocardiographic quantification of stenotic valvular lesions. Echocardiography 4:289-303
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9. Nicolosi GL, Dall’Aglio V, Bitto S, Burelli C, D’Angelo G, Lestuzzi C, Mimo R. Moro E, Pavan D, Zardo F, Zanuttini D (1987) In: Cardiologia 1987, RoveTIi F (ed) Color Doppler: una nuova filosofia dell’immagine.Librex,Mi1ano,pp 449-458
10.Pearlman AS, Otto CM (1987) Quantification of valvular regurgitation. Echocardiography 4:271-287
11.Perry GJ, Nanda NC (1987) Recent advances in color Doppler evaluation of valvular regurgitation. Echocardiography 4:503-513
12. Perry GJ, Nanda NC (1986) Diagnosis and quantitation of valvular regurgitation by color Doppler flow mapping. Echocardiography 3:493-503
13. Switzer DF, Nanda NC (1985) Color Doppler evaluation of valvular regurgitation. Echocardiography 2:533-543
14.Pennestri F, Loperfido F, Salvatori MP, Mongfardo R., Ferrazza A, Guccione P, Manzoli U (1984) Assessment of tricuspid regurgitation by pulsed Doppler ultrasonography of the hepatic veins. Am J Cardiol 54:363-368
15.DeMaria AN. Spain MG, Garrahy P, Grayburn PA, Kwan OL, Smith MD (1987) Considerations in the quantitation of color Doppler flow imaging. Echocardiography 4:495-501

 

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