Transesophageal echocardiographic features of

normal and dysfunctioning bioprosthetic valves

Transesophageal and transthoracic echocardiography and color flow Doppler were performed in patients with 42 normal and 20 dysfunctioning bioprosthetic mitral and aortic valves. Transesophageal echocardiography was superior to the transthoracic approach in delineating bioprosthetic valve cusps and the presence of valve thickening due to valve degeneration. In 27 clinically normal bioprosthetic mitral valves, regurgitation was demonstrated in three patients by the transthoracic approach and in seven by transesophageal study. Both transesophageal and transthoracic color flow Doppler demonstrated mitral regurgitation in 17 clinically regurgitant valves. The severity of mitral regurgitation was accurately assessed by the transesophageal study in all 13 patients who underwent angiography, whereas the transthoracic imaging underestimated valvular regurgitation in 7 of the 13 cases (54%). Bioprosthetic aortic valves were normal on clinical examination in 15 patients and were regurgitant in three others. Both transthoracic and transesophageal color flow Doppler were of equal value in observing and quantifying aortic regurgitation. In five clinically normal and regurgitant mitral and aortic valves, transesophageal color flow Doppler revealed eccentric regurgitant jets suggestive of paravalvular leak. This feature was not evident by the transthoracic approach. In conclusion, transesophageal echocardiography and color flow Doppler are superior to transthoracic imaging in estimating bioprosthetic mitral, but not aortic regurgitation, in differentiating valvular from paravalvular regurgitation, and in demonstrating thickened valves due to cusp degeneration. (AM HEART J 1991;121:1149.)

Mohsin Alam, MD, Jeffrey B. Serwin, MD, Howard S. Rosman, MD,

Gerard0 A. Polanco, MD, Irene Sun, RN, RDMS, and Norman A. Silverman, MD. Detroit, Mich.

Bioprosthetic cardiac valves have been in clinical use for over 15 years.l These valves have a low throm- boembolic risk profile, but with time they become dysfunctional due to cusp degeneration. Transtho- racic echocardiography and color flow Doppler have been useful in evaluating valve degeneration.2 Recent studies, however, have shown that compared with angiography, bioprosthetic mitral valve regurgita- tion was underestimated in 32 % and aortic valve re- gurgitation was underestimated in 13% of patients using transthoracic color flow Doppler imaging.3 Transesophageal echocardiography and color flow Doppler imaging have shown promise in evaluating a few patients with bioprosthetic valves.4 However, to date there have been no large studies of these valves by the transesophageal approach. In this report, we

From the Henry Ford Heart and Vascular Institute, Department of Anaes- the&. Henry Ford Hospital.

Received t’or publication June 11, 1990; accepted Sept. 18, 1990.

Reprint requests: Mohsin Alam, MD, Echo Doppler Laboratory, Henry Ford Heart and Vascular Institute, Henry Ford Hospital, 2799 West Grand Blvd.. Detroit, MI 48202.

4/l/27165

describe our experience with 42 normal and 20 degenerated and regurgitant bioprosthetic mitral and aortic valves.

METHODS

Study patients. Transesophageal echocardiography and color flow Doppler studies were performed in 56 patients with 62 bioprosthetic valves-44 mitral and 18 aortic valves. By clinical examination, 42 were presumed to be functioning normally (Table I) and 20 were regurgitant due to spontaneous degeneration of the cusps (Table II). All patients with dysfunctioning valves presented one or more of the following clinical features: dyspnea on exertion, re- gurgitant murmurs with or without musical features, con- gestive heart failure, and hemolytic anemia. Valve dys- function was confirmed by cardiac catheterization and valve surgery in 16 instances. Valve replacement surgery was performed either the same day or within 34 days (mean = 12 days) of transesophageal study. The remaining four patients with regurgitant valves have New York Heart Association class II dyspnea and are being treated medi- cally.

Echocardiography and color flow Doppler. Transtho- racic and transesophageal echocardiography and color flow Doppler studies were performed the same day (54 valves)

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Table I. Features of normally functioning bioprosthetic valves

Valve location

Valve cusp features

TTE TEE TTE

Valve regurgitation

TEE

Mitral (n = 27) Normal 25 Normal 21 Absent 24 Absent 20 Thickened 2 Thickened 6 Present 3 (mild) Present 7 (5 mild, 2 moderate)

Paravalvular 2

Aortic (n = 15) Normal 15 Normal 15

TEE, Transesophageal imaging; TTE, transthoracic imaging.

Absent 13 Present 2 (mild)

Absent 14 Present 1 (mild)

Table II. Features of dysfunctioning bioprosthetic valves*

Valve function Transthoracic Transesophageal echo and CFD echo and CFD

Angiographyl hemodynamics Surgical findings

Mitral regurg (n = 17)

Aortic regurg (n = 3)

Thickened cusps 6

Flail cusp 1 Severe regurg 6 Moderate regurg 3 Normal cusp 3 Severe regurg 2 Moderate regurg 1

Thickened cusps 8

Flail cusp 3 Severe regurg 13 Moderate regurg 4 Normal cusp 3 Severe regurg 2 Moderate 1

paravalve regurg

Severe regurg 13

NP 4 Severe regurg 2

Moderate regurg 1

Degenerated 11 torn cusps

Paravalve 2 Torn cusps 2

Paravalve 1

CFD, Color flow Doppler; NP, not performed; Paravalve, paravalvular leak; regurg, regurgitation. *Each patient can have more than one ultrasound finding.

or within 3 weeks (eight valves) of each other. At the time of the transesophageal study, all bioprosthetic valves had been implanted for a mean interval of 71 months (range, immediately following operation to 182 months). The transesophageal ultrasound was performed with a 5 MHz phased array imaging transducer mounted on the distal tip of a 100 cm gastroscope (Model 21352-A, Hewlett-Packard Co., Medical Products Group, Andover, Mass.) by previ- ously described techniques.5 In eight patients the transe- sophageal study was performed in the operating room im- mediately after valve replacement surgery, whereas with 54 other valves the tests were performed in the echocardio- graphic laboratory on awake patients. One patient had two transesophageal studies performed within 11 weeks of each other as she developed new regurgitant murmur and con- gestive heart failure symptomatology after the first test. All patients were premeditated with intravenous antibiotic prophylaxis 30 to 60 minutes before the transesophageal procedure.

All valves were evaluated by color flow Doppler imaging for the presence or absence of valve regurgitation. The color flow Doppler regurgitant jet area, duration, location, shape, and color characteristics were evaluated by playing back the videotape and by frame-by-frame analysis. In all instances, good quality echocardiographic and color flow Doppler images were obtained by both transesophageal and transthoracic approaches. In all patients the color flow

Doppler gain/reject was adjusted just to the level where background noise was seen.

The extent of the regurgitant prosthetic mitral/aortic valve color flow jet by transthoracic and transesophageal Doppler was related to the corresponding receiving cham- bers by gross visual inspection.“, 7 The valve regurgitation was graded from systolic or diastolic frames in which the regurgitant jet reached its maximal extent. In case of mul- tiple jets, the total area covered by each jet was added up and was related to the corresponding chamber. As the left atrium could not be imaged in its entirety in one pie-shaped transesophageal plane, the mitral regurgitant jet was related to the atria1 chamber by gross visual inspection rather than by left atria1 area measurements. Thus with mitral prosthetic valves the regurgitation was graded mild when the color flow jet occupied less than 20% of the left atria1 chamber. With moderate regurgitation, the color flow jet occupied 20% to 40% of the left atrial chamber, and with severe regurgitation, the color flow jet occupied more than 40 % of the left atria1 chamber.6 Bioprosthetic aortic regurgitation was similarly quantitated by relating the width of the proximal jet to the left ventricle outflow tract. Thus with mild aortic regurgitation, the proximal regur- gitant jet was less than half the width of the left ventric- ular outflow tract. With moderate regurgitation, the width of the proximal regurgitant was one half to two thirds of the left ventricle outflow tract, and with severe regurgitation,

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Fig. 1. Transesophageal color flow Doppler demonstrates a mild, centrally located regurgitant jet (MW in a patient with clinically normal bioprosthetic valve in the mitral position. LA, Left atrium; LV, left ven- tricle; MV, mitral valve; MR, mitral regurgitant jet; RV, right ventricle.

Fig. 2. Transesophageal echocardiogram of a patient with a normally-functioning bioprosthetic valve in the mitral position. Note the three normal thin-appearing valve cusps (arrows). LA, Left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; ST, valve stents.

the width of the regurgitant jet was greater than two thirds of the left ventricle outflow tract.7

RESULTS

Clinically normal bioprosthetic valves in the mitral po- sition. Of the 27 mitral valves judged to be clinically

normal and without regurgitant murmurs, trans- esophageal color flow Doppler demonstrated no re- gurgitation in 20, mild regurgitation in five (Fig. l), and moderate regurgitation in two patients. One of the presumed clinically normal patients with moder- ate regurgitation assessed by transesophageal color

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Fig. 3. Transesophageal color flow Doppler image demonstrates a severely regurgitant bioprosthetic valve in the mitral position. Note the centrally located regurgitant jet extending in the left atria1 chamber. LA, Left atrium; LV, left ventricle; MV, mitral valve; MR, mitral regurgitant jet.

flow Doppler presented 11 months later with in- creased symptoms and with transesophageal and an- giographic evidence of severe mitral regurgitation. The regurgitant jet was centrally located in five pa- tients and was outside the confines of the valve ring (paravalvular) in two instances. In contrast, trans- thoracic color flow Doppler demonstrated mild mi- tral regurgitation in three of these patients and it was not possible to ascertain if the regurgitant jet was valvular or paravalvular.

Transesophageal two-dimensional echocardio- graphy demonstrated all three bioprosthetic cusps in all instances. The cusp echoes were clearly distin- guishable from echo-reflective stents by virtue of their opening and closing motion. The cusps had a fine linear (normal valve) appearance (Fig. 2) in 21 patients, whereas in six others increased cusp echoes (thickened valves) were observed. Three of these six thickened valves had concomitant regurgitation. In contrast, increased cusp echoes were observed in only two instances by transthoracic echocardiography.

Regurgitant bioprosthetic valves in the mitral position. Of the 17 clinically regurgitant mitral bioprostheses, transesophageal color flow Doppler imaging demon- strated moderate regurgitation in four patients and severe regurgitation in 13. All 13 severely regurgitant valves also had angiographic features of severe mitral regurgitation. The regurgitant jet was centrally lo- cated in 15 (Fig. 3) and was eccentric (paravalvular) in two patients (Fig. 4). In 15 instances one single color flow regurgitant jet was observed, whereas in

two others, two distinct jets were observed. Tran- sthoracic color flow Doppler detected regurgitation in all 17 patients, but compared with angiography tended to underestimate its severity in 7 of 13 (54 9% ) instances (Table II). Furthermore, it was not possi- ble to differentiate a paravalvular regurgitant jet from a valvular jet by this approach. At the time of valve surgery, 11 patients had torn cusps with or without cusp thickening, and two others had para- valvular regurgitation. Transesophageal two-dimen- sional echocardiography also demonstrated flail mo- tion of the torn valve cusp into the left atrium during systole in three, and thickened cusps (Fig. 5) in 8 of 17 patients. In contrast, transthoracic study demon- strated flail motion in one and thick cusps in six in- stances.

Clinically normal bioprosthetic valves in the aortic position. Of the 15 patients with clinically normal aortic valves, transesophageal color flow Doppler demonstrated no regurgitation in 14 and mild regur- gitation in one. Transthoracic color flow Doppler demonstrated mild regurgitation in two of these pa- tients. In some instances, varying degrees of flow masking the left ventricular outflow tract occurred by the metallic valve ring and stents as seen by trans- esophageal imaging. However, valve cusps were more clearly demonstrated by transesophageal (as opposed to transthoracic) two-dimensional echocardiography. The cusps appeared thin and normal in all 15 instances.

Regurgitant bioprosthetic valves in the aortic position.

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Fig. 4. Transesophageal color flow Doppler image demonstrates a severely paravalvular regurgitant bio- prosthetic valve in the mitral position. Note that the origin of the regurgitant jet is eccentrically located and directed toward the left atria1 appendage (LAA). LA, Left atrium; LV, left ventricle; MV, mitral valve; MR, mitral regurgitant jet.

Fig. 5. Transesophageal echocardiogram of a thickened and degenerated bioprosthesis in the mitral po- sition. Note the thickened cusp (C) with increased cusp echoes during diastole. C, Valve cusps; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; ST, valve stents.

In all three patients with a moderate to severe regur- instances and its point of origin was centrally locr gitant bioprosthetic aortic valve, the transesophageal in two and was eccentric (Fig. 6) in one patient. AI and transthoracic color flow Doppler images cor- time of surgery the patient with the eccentric jet rectly demonstrated and quantitated the severity of found to have paravalvular regurgitation and valve regurgitation (Table II). The transesophageal other two had valvular regurgitation due to torn color flow regurgitant jet was holodiastolic in all three generated cusps.

sted ; the was the de-

April 1991 I 154 Alam et al. American Heart Journal

Fig. 6. Color flow Doppler image demonstrates a moderately paravalvular regurgitant bioprosthetic aor- tic valve. Note that the aortic regurgitant jet (AR) is eccentric at its point of origin (arrow) and extends into the left ventricular outflow tract. A, Aortic valve; LA, left atrium; LV, left ventricle; ST, valve stents.

DISCUSSION

Transesophageal two-dimensional echocardio- graphy has provided a new window in the evaluation of bioprosthetic cardiac valves.4 With this approach, high-frequency, high resolution transducers greatly improve the quality of ultrasound and color flow Doppler images. In our study, excellent views of bioprosthetic valve cusps were obtained by trans- esophageal echocardiography. The presence of valve cusp thickening due to valve degeneration and/or calcification was more clearly demonstrated by transesophageal as contrasted to transthoracic imag- ing. Transesophageal two-dimensional echocardio- graphy, however, could not differentiate a thickened valve resulting from degeneration from one resulting from infection.

Transthoracic color flow Doppler recognized all 17 regurgitant bioprosthetic mitral valves but underes- timated the severity in 7 of the 13 (54 96 ), when com- pared with an angiogram or surgical disclosure. The underestimation of mitral regurgitation by the trans- thoracic approach can be explained by attenuation of the sound beam and by reverberation from the echo- reflective valve ring and stents, masking the left atrium. The degree of left atria1 flow masking, al- though not as pronounced as with mechanical mitral valve prostheses,8 can nonetheless significantly re- duce the sensitivity of transthoracic color flow Dop- pler imaging in quantitating the severity of biopros- thetic mitral regurgitation. The patients without

clinical mitral regurgitation but with transesoph- ageal color Doppler paravalvular regurgitation are, strictly speaking, not normal individuals but have mild subclinical paravalvular regurgitation. Some of our patients also had thickened valve cusps. We9 have previously reported that valve thickening dem- onstrated by transthoracic imaging identified patients at higher risk for subsequent valve dysfunc- tion. In this study we were able to demonstrate dete- rioration of mitral regurgitation from a moderate to a severe grade by transesophageal color flow Doppler imaging in a patient who developed clinical valve dysfunction.

In two normal and in three moderate to severely regurgitant mitral and aortic valves, the origin of the color flow jet was eccentric, located outside the con- fines of the valve ring. This feature was suggestive but was not diagnostic of paravalvular regurgitation, as cusp tears could be eccentric, involving the valve at its ring. Furthermore, three-dimensional imaging, even with transesophageal two-dimensional echocar- diography, is not possible. In three instances para- valvular origin of the valve regurgitation was con- firmed at surgery.

In our hands, transesophageal color flow Doppler imaging was not superior to the transthoracic ap- proach in diagnosing and quantitating bioprosthetic aortic valve regurgitation. This is partly because bio- prostheses in the aortic position are well suited for color flow Doppler analysis by the transthoracic ap-

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preach. Furthermore, flow masking of the left ven- tricular outflow tract does not occur from this ultra- sound window. However, superior quality images of the aortic valve cusps obtained by transesophageal two-dimensional echocardiography make this a bet- ter overall method than the transthoracic imaging.

In conclusion, transesophageal echocardiography and color flow Doppler are superior to the transtho- racic approach in: (1) estimation of the severity of bioprosthetic valve regurgitation in the mitral but not in the aortic position; (2) differentiation of mitral and aortic valvular from paravalvular regurgitation; and (3) demonstration of normal as well as thickened and flail valves due to cusp degeneration.

We thank Drs. Fareed Khaja, James Brymer. Thomas McFar- land, Philip Kraft, and Vivian Clark for providing cardiac cathe- terization data; Lois Graham, Patricia Bailey, Debbie Upshaw, Valerie Knight, Patricia Jankowski, Ninfa Buckley, Darlene Mc- Broom, and Drs. Mita Sheth, Remigio Garcia, Syed Jafri, Ali Moosvi, Walter Kao, and Stephen Smith for their technical assis- tance in data collection; and Elaine Buss and Patricia Alam of typing the manuscript.

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4. Nellessen IT, Schnittger I, Appleton CP, Masuyama 1’. Bolger A, Fischell TA, Tye T, Popp RL. Transesophageal two- dimensional echocardiography and color Doppler flow veloc- ity mapping in the evaluation of cardiac valve prostheses. Cir- culation 1988;78:848-55.

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