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Does multiplane transesophageal echocardiography improve the assessment of prosthetic valve regurgitation?
Does Multiplane Transesophageal Echocardiography Improve the Assessment of Prosthetic Valve Regurgitation? Frank A. Flachskampf, MD, Raincr Hoffmann, MD, Andreas Franke, MD, Frank P. Job, MD, Friedrich A. Sch6ndube, MD, Bruno J. Messmer, MD, and Peter Hanrath, MD, Aachen, Germany
Assessment of prosthetic valve regurgitation by echocardiography remains d i ~ o d t . To study the value of the newly introduced multiplane transesophageal technology for this purpose, prosthetic valve regurgitation was examined in 63 consecutive patients with 35 mitral and 33 aortic prostheses (23 bioprostheses and 45 mechanical prostheses). Transvahadar, paravalvular and, in mechanical valves, normal or pathologic transvalvular regurgitation were identified first with 0 degrees (transverse) and 90 degrees (longitudinal)planes combined with flexion of the echoscope tip and then additionally with multiple intermediary planes by transducer rotation. In a subgroup of 20 patients interobserver variability was evaluated. Both methods showed regurgitation in 56 of 68 valves; one additional case of regurgitation was seen by multiplane imaging only. However, 19 cases of regurgitation were not clearly classifiable by biplane transesophageal echocardiography compared with only three with multiplane transesophageal echocardiography. Grading of severity was concordant by both modalities in 66 and discordant in only two cases. Observers disagreed on severity in two of 20 cases based on biplane imaging but in none based on multiplane imaging; classification of regurgitation differed in six of 20 (biplane) and one of 20 (multiplane), respectively. Multiplane transesophageal imaging improves classification of prosthetic regurgitation but has little effect on severity grading. (J AM Soc ECHOCARDIOGR1995;8:70-8.)
Since the advent of Doppler echocardiography it has been increasingly recognized that regurgitation frequently occurs in prosthetic valve replacement. TM This regurgitation can be subdivided into closure backflow occurring during valve closure and leakage backflow occurring as a result of transvalvular or paravalvular leakage after Valve closure, s Almost all mechanical prostheses exhibit a minor degree of normal transvalvular regurgitation even when intact, and bioprostheses develop transvalvular regurgitation in the course of degenerative or infectious changes. However, in vivo differentiation of normal versus pathologic and transvalvular versus paravalvular regurgitation often remains difficult. From the Med Klinik I and the Klinik ffir Herzchirurgie,Thoraxchirurgie trod Gef~a~chirurgie,RWTH Aachen,Germany. Reprint requests: Frank A. Flachskampf,MD, Med. Klinik I, RWTH Aachen, Pauwelsstr. 30, 52057 Aachen, Germany. Copyright9 1995 by the AmericanSocietyof Echocardiography. 0894-7317/95/$3.00 + 0 27/1/56827
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Transesophageal color Doppler, because of its superb image quality and resolution, can often identify typical patterns of normal leakage backflow that depend on the design of the examined valve. 6-1~Because such patterns can bc complex, multiple cross-sectional planes may be needed for clear understanding of the three-dimensional jet shape. Recently multiplane transesophageal echocardiography T M that is capable of continuous rotation of the cross section from a stable transducer position has been introduced. In this study the value of this technique for the evaluation of prosthetic valve regurgitation was assessed.
METHODS
We studied 63 consecutive patients (age 60 +- 10 years, range 30 to 79 years) with 35 mitral and 33 aortic prostheses (five patients had both mitral and aortic prostheses) who underwent transesophageal
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Table 1 Position and type of examined prosthetic valves Mechanical Mitral prostheses Aortic prostheses
Total no.
Bioprostheses
prostheses
35 (32) 33 (25)
15 (13) 8 (5)
20 (19) 25 (20)
Presence of regurgitation of any type is denoted in brackets.
examination with the multiplanc probe because of clinically suspected prosthetic valve dysfunction, endocarditis, or embolism (Tablc 1). All patients gave written informed consent. Patient files of in-hospital treatment and follow-up visits as well as surgery records were reviewed whcre applicable to detcct whether patients diagnosed as having normal regurgitation had clinical evidence of prosthetic valve failure during the next 2 months and whether surgical findings matched transesophageal echocardiographic diagnoses. Details of the multiplanc cchoscope have been described previously, n Twenty-three bioprostheses (Carpentier-Edwards [American Edwards Laboratories, Irvine, Calif.] and Hancock [Medtronic Inc., Minneapolis, Minn.]) and 45 mechanical prostheses (31 St. Jude Medical [St. Jude Medical, St. Paul, Minn.], 6 Bj6rk-Shiley [Shiley Inc., Irvine, Calif.], 2 Medtronic-Hall [Medtronic Inc.], 2 Duromedix [American Edwards], 2 Starr-Edwards [American Edwards], and 1 Smeloff-Cutter [Cutter Biomedical, San Deigo, Calif.], 1 Sorin [Sorin Biomedica, Saluggia, Italy]) were studied. The vanes were studied: (1) first with only the 0degree and 90-degree plane orientations (corresponding in orientation to the transverse and the longitudinal plane in biplane transcsophageal echocardiography) together with sideward flexion of the echoscope tip, and then (2) with multiple intermediate plane orientations and continuous back-andforth rotation as needed. Color gain settings were not changed when the imaging plane was rotated. The mitral valve was examined from a stable transesophageal transducer position by stepwise rotation of the cross-sectional and color Doppler plane for comprehensive scanning of the whole circumference. To examine aortic prostheses, exact short- and long-axis views (at approximately 60 degrees and 150 degrees, respectively) were obtained. For clarification of shape and origin of aortic regurgitant jets, the imaging plane was rotated back and forth between these views while the echoscope tip was left in place. At both sites special attention was given to definition of the origin of the jet with respect to the
prosthetic valvular ring. To exclude mere closure leakage color Doppler regurgitant jets had to be confirmed by pulsed wave Doppler to be present throughout the part of the heart cycle in which the valve was closed. Regurgitant jets were classified as normal transvalvular regurgitation (in mechanical prostheses), if they followed known normal spatial patterns in number, size, and orientation of jets. 9,1~ They were classified as pathologic transvalvular regurgitation, if the regurgitant jet originated clearly within the valve ring and did not follow patterns of normal transvalvular regurgitation in mechanical valves, or was more than trace in bioprosthetic valves. They were classified as paravalvular regurgitation, if the regurgitant jet originated clearly outside the valve ring. They were classified as regurgitation of uncertain type, if the above criteria were not met. Regurgitation severity was graded visually. In mitral regurgitation, assessment was based on the maximal size of the color jet area or the sum of the maxinlal areas, as previously reported, without normalization for atrial size14; regurgitant jet area less than 3 cm 2 was classified as mild, 3 to 6 cm 2 as moderate, and more than 6 cm2 as severe mitral regurgitation. Additionally, blunted or reversed systolic forward flow in the left upper pulmonary vein had to be present to count regurgitation as moderate or severe.iS In aortic regurgitation, grading relied on the fraction of the outflow tract maximally occupied by regurgitant jet flow during diastole, as previously described for transthoracic echoat; a fraction of less than 25% was classified as mild, 25% to 59% as moderate, and 60% or more as severe. It is recognized, however, that grading of regurgitation severity based on color jet areas is at best semiquantitative and that difficulties are encountered especially when dealing with eccentric jets. In a subgroup of 20 consecutively examined prosthetic valves interobserver variability was analyzed with the following protocol: during image acquisition two-dimensional and color Doppler imaging in the transverse and longitudinal planes only was also recorded on a separate tape. Rotation between transverse and longitudinal planes was not recorded on the additional tape. Tapes containing the full mul-
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Figure 1 Normal regurgitation in St. Jude Medical valves. A, Schematic drawing of normal pattern of leakage backflow occurring through closed valve, viewed from two perspectives. Reproduced with permission from the American College of Cardiology. 9 B, Example of predicted pattern in mitral prosthesis imaged in two orthogonal but intermediate (neither transverse nor longitudinal) planes (le#, 30 degrees, right, 115 degrees). LA, Left atrium.
tiplane examination and those containing only biplane recordings were reviewed in a random order by two experienced echocardiograpbers. RESULTS
No complications or failures occurred with the mnltipiane echoscope. Biplane and muitipiane technique diagnosed the presence of leakage in a similar number of valves: 56 of 68 with biplane and 57 of 68 with multiplane transesophageal echocardiography. The additional case was a small paravalvular leak in a mitral prosthesis not seen with the biplane approach. Classification o f Regurgitation Type
Multiplane examination in the described fashion allowed a better definition of regurgitation type. By the biplane approach, in 19 of 56 prostheses showing regurgitation, the type of regurgitation was not
clearly defined; in contrast, in only three cases (all in the aortic position and all of mild severity) the type of regurgitation remained unclear after multiplane examination. O f these 19 cases 11 were aortic, and eight were mitral prostheses; five were bioprostheses, and 14 were mechanical valves. Multiplane transesophageal examination identified these cases as normal transvalvular only (six); paravalvular only (five); pathologic transvalvuiar only (four); normal transvalvular and paravalvular (one); paravalvular and pathologic transvalvular (one); and unclear (three). As expected the two examined Starr-Edwards valves did not show transvalvular leakage. The findings are summarized in Table 2. Better definition of regurgitation type was possible by (1) improving the recognition of normal patterns, for instance, the complex pattern of bileaflet prostheses (Figure 1) or the typical peripheral symmetric jets in tilting disc prostheses (Figure 2); (2) allowing the examiner to choose an optimal intermediate cross-sectional plane to define the origin of
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Figure 2 Symmetric, peripheral normal transvalvular regurgitation in Bj6rk-Shiley CC mitral prosthesis occurring between valve ring and occluding disk, imaged in intermediate (45 degrees) plane. LV, Left ventricle; RA, right atrium.
Table 2 Classification of type and severity of regurgitation in 68 valve prostheses by biplane and multiplane transesophageal echocardiography Regurgitation
Biplane
Multiplane
Type Normal transvalvular Pathologic transvalvular Paravaivular Uncertain type
23 7 9 19
30 11 18 3
Severity N o regurgitation Mild regurgitation Moderate Severe
12 35 15 6
11 35 15 7
Numbers indicate prostheses in which regurgitation was found. Note that in some prostheses two types of regurgitation were found (two cases by biplane and five cases by multiplane examination).
a regurgitant jet outside or inside the prosthetic valve ring (examples of pathologic regurgitation are displayed in Figures 3 to 6); and (3) enabling the examiner to rotate the viewing plane back and forth without echoscope tip motion to follow the spatial course of a jet (Figures 3, 6). No patient diagnosed as having normal regurgitation had a clinical course during the next 2 months suggesting severe regurgitation or necessitating angiography or surgery. In nine patients o f our study group surgery was performed. Six patients had a diagnosis of severe
transvalvular regurgitation; surgery confirmed massive degenerative lesions in five bioprostheses, including one with a flail leaflet, and in one case thromboric immobilization of a Bj6rk-Shiley prosthesis occurred. Severe paravalvular regurgitation was diagnosed before the operation in two patients, and the location o f the paravalvular leaks (at the lateral mitral circumference and in the noncoronary sinus o f Valsalva) was confirmed at surgery. One patient with a mitral St. Jude Medical prosthesis was operated on because of embolizing endocarditis; transesophageal echocardiography had shown only nor-
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Figure 3 Paraval~allarleak in St. Jude Medical aortic valve prosthesis. Left, long-axis view at 125 degrees; right, short-axis view at 45 degrees. Note that origin and (in short axis) course of paravalvular leakage can be located outside ring of prosthesis. AOA, Ascending aorta; AVR, aortic valve replacement. mal transvalvular regurgitation, and no leak or dehiscence of the prosthesis was observed during the operation.
Grading of Regurgitation Severity Grading of regurgitation showed little diffcrence between the biplane and the multiplane approach. Apart from the one cited paravalvular leak not seen by biplane examination, one case of regurgitation in a mitral bioprosthesis was graded moderate by biplane and severe by multiplane examination, and regurgitation in one mechanical mitral prosthesis was graded mild by biplane and moderate by multiplane examination. Grading is summarized in Table 2.
Interobserver Variability
Figure 4 Paravalvular leak in St. Jude Medical mitral prosthesis. Origin of jet is recognizable in 37-degree plane (arrows). Note also small normal transvahaflar regurgitation jets.
Thc two independcnt observers differcd with regard to severity of regurgitation in 2 of 20 cases (10%) when evaluating biplane images only (in both cases one observer graded regurgitation as mild, the othcr as moderatc); they had complete accordance (20 of 20) when cvaluating severity by multiplane recordings. The differences between classification of type of regurgitation were as follows: on thc basis of thc biplane recordings classification differcd in 6 of 20 cases (30%). In these cases one observer diagnosed paravalvu]ar leakage in all six valves, whereas thc other diagnosed unclear type of regurgitation twice, paravalvular leakage and additional normal transvalvular regurgitation twice, pathologic transvalvular re-
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Figure 5 Transvalvular regurgitation in mitral bioprosthesis. Left, at 0 degrees, one central regurgitant jet is seen, but image of origin is not obtained in this plane. Right, in intermediate plane (52 degrees), two distinct transvalvular regurgitant jets, one central and one eccentric, are seen. They originate within valve ring. gurgitation once, and normal regurgitation only once. In contrast, based on the multiplane examinations only one ( 5 %) case of disagreement occurred, where one observer diagnosed a paravalvular leak, and the other diagnosed paravalvular and normal transvalvular leakage.
DISCUSSION Background Prosthetic regurgitation can be classified as closure backflow, occurring with the closure of the valve occluder or bioprosthetic leaflets; and leakage backflow, taking place after the valve is shut. s It has been shown that except for the Starr-Edwards ball-in-cage valve, all mechanical valves by design exhibit some degree of leakage backflow, often at the hinge points of the occluder (as in the St. Jude Medical bileaflet valve) (Figure 1), or around a central strut (as in the Medtronic-Hall valve), or between valve ring and central occluder (as in the Bj6rk-Shiley valve) (Figure 2). 9H Bioprostheses in vivo also often show transvalvular leakage of varying degree, most likely caused by degenerative changes, a,4 Another type of prosthetic valve regurgitation is paravalxaflar leakage, which has been recognized to occur quite frequently, and which especially in mechanical prostheses is difficult to distinguish from peripheral transvalvular leakage.
Prosthetic regurgitation patterns are identified par, ticularly well by transesophageal color Doppler because of its excellent image quality and spatial resolution. Initial studies used monoplane echoscopes,6-8 but monoplane transesophageal echocardiography provides only a limited array of cross-sectional planes even with the sideward flexion of the echoscope tip. Furthermore complete examination of mitral prostheses requires a pullback of the instrument from the gastroesophageal junction, where almost a frontal short-axis view of the prosthesis is obtained, to the high transesophageal position, where a horizontal transverse cross-section is imaged. Thus the angle between mitral prosthesis ring plane and the imaging sector changes continuously during this procedure, as does the transducer position, making spatial orientation difficult for the examiner. In aortic prostheses precise short- and long-axis views often are difficult to obtain with monoplane instruments. Recently biplane echoscopes have enhanced the diagnostic capabilities, and the value of biplane transesophageal echocardiography, especially in the assessment ofmitral regurgitation, has been shown.17,18 However, the planes acquired with these instruments have different spatial origins, because longitudinal and transverse transducers constitute two separate element sets, and because intermediate planes require sidewards flexion of the tip that houses the two transducers. Thus understanding of complex spatial relationships remains difficult for the examiner. Fur-
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Figure 6 A, Regurgitation in mitral bioprosthesis. Transverse (0 degrees, left) and longitudinal (90 degrees, right) cross-sections fail to identify precise origin with respect to valve ring. B, Intermediate planes visualize origin and course of one paravalvular (137 degrees, left) and one eccentric transvalvular (70 degrees, right) jet. LAA, Left atrial appendage.
thermore use of the sideward flexion sometimes is unpleasant for the patient. Multiplane transesophageal echocardiography constitutes the latest innovation in this field, H-x3providing complete and easy access to intermediary cross-sections without the need for change of transducer position and thus without shift in the imaging sector origin. Clinical Significance o f the Present Study
Because grading of regurgitation by the size of color Doppler jet areas has well-recognized limitations and
can be misleading, 19 identification of regurgitant jet origin and of typical regurgitant jet patterns is an important issue for the distinction between pathologic and normal conditions. Because normal transvalvular regurgitation in mechanical valves often originates eccentrically, for example in the St. Jude Medical bileaflet prostheses, differentiation from paravalvular leakage is particularly difficult if the optimal imaging plane cannot be achieved or maintained to define whether the jet originates inside or outside the sewing ring of the prosthesis.
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The unique ability of the mukiplane transducer to obtain multiple cross-sections from a single stable transducer position allows easier and more confident diagnosis of the type of prosthetic regurgitation. Moreover this technique almost obviates the need for lateral flexion of the echoscope tip. In our experience with this technique only minimal lateral adjustments, mostly to improve contact with the esophageal wall, were required. Although only one case of regurgitation was completely missed with biplane transesophageal echocardiography, in 16 of 56 valves the type of regurgitation was clarified only with the multiplane technique. In contrast only small differences were seen in grading of severity; multiplane examination led to an upgrade by one step in the two discordant cases. The main value of this technique therefore is not higher sensitivity or better semiquantitation of regurgitation but the improved classification of type, especially in cases with mild or moderate regurgitation. Another important finding is that observers agreed more on classification and grading based on multiplane rather than on biplane examinations, confirming that multiplane examination defined regurgitation more clearly. Limitations
Classification of regurgitation in this study is based on thc examiner's expertise, and no independent gold standard is offered. Furthermore grading of severity based on color jet area has well-known limitations, especially when assessing aortic prosthetic regurgitation from a transesophageal window, where shadowing is an additional drawback. However, there is presently no technique as sensitive for the detection of prosthetic valve regurgitation as transesophageal echocardiography that could serve as an independent standard. In the nine patients who had surgery, the transesophageal findings were confirmed, and in the patients classified as having normal regurgitation the clinical course showed no evidence contradicting this classification. Another important drawback of this study is that comparison of biplane and multiplane technique was not based on separate examinations and examiners, because this was not deemed ethically justified in the awake patient. To partially circumvent this problem we analyzed interobserver variability in a subgroup by using different tapes for the two parts of the examination and reviewing them in a blinded fashion. The lower variability found for multiplane examination indicates better definition of prosthetic regurgitation by this technique.
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Conclusion
Multiplane transesophageal echocardiography clarifies the spatial relationships between valve ring and jet origin and course and thus improves classification of the type of prosthetic regurgitation. Grading of regurgitation, however, is only marginally affected by this technique. The authors thank James D. Thomas, MD, Cleveland, for
review of and thoughtful advice on this manuscript.
REFERENCES
1. Alam M, Rosman HS, Lakier JB, et al. Doppler and echocardiographic features of normal and dysfunctioning bioprosthetic valves. J Am Gall Cardiol 1987;10:851-8. 2. Kapur AK, Fan P, Nanda NC, Yoganathan AP, Goyal RG. Doppler color flow mapping in the evaluation of prosthetic mitral and aortic valve fianction, }" Am Gall Cardiol 1989;13:1561-71. 3. Chambers J, Monaghan M, Jackson G. Colour flow Doppler mapping in the assessment of prosthetic valve regurgitation. Br Heart J 1989;62:1-8. 4. Teoh KH, Ivanov J, Weisel RD, Daniel LB, Darcel IC, Rakowski H. Clinicaland Doppler echocardiographic evaluation of bioprosthetic valve failure after 10 years. Circulation 1990;82(supp! IV):110-6. 5. Dellsperger KC, Wieting DW, Baehr DA, Bard RJ, Brugger JP, Harrison EC. Regurgitation of prosthetic heart valves: dependence on heart rate and cardiac output. Am J Cardiol 1983;51:321-8. 6. Nellessen U, Schnittger I, Appleton CP, et al. Transesophageal two-dimensional echocardiography and color Doppler flow velocity mapping in the evaluation of cardiac valve prostheses. Circulation 1988;78:848-55. 7. Taams MA, GussenhovenEJ, CahalanMK, et al. Transesophageal Doppler color flow imaging in the detection of native and Bj6rk-Shileymitral valveregurgitation. J Am Coil Cardiol 1989;13:95-9. 8. van den Brink RBA, Visser CA, Basart DCG, Dtiren DR, de Jong AP, Dunning AJ. Comparison of transthoracic and transesophageal color Doppler flow imaging in patients with mechanicalprostheses in the mitral valveposition. Am J Cardiol 1989;63:1471-4. 9. Flachskampf FA, Guerrero JL, O'Shea JP, Weyman AE, Thomas JD. Patterns of normal transvalvular regurgitation in mechanical valve prostheses. J Am Coil Cardiol 1991; 18:1493-8. 10. Baumgartner H, Khan S, DeRobertis M, Czer L, Maurer G. Color Doppler regurgitant characteristics of normal mechanical mitral valveprostheses in vitro. Circulation 1992;85:32332. 11. Flachskampf FA, Hoffmann R, Verlande M, Ameling W, Hanrath P. Initial experience with a multiplane transesophageal echotransducer: assessmentof diagnostic potential. Eur Heart J 1992;13:1201-6. 12. Roelandt JRTC, Thomson IR, Vletter WB, Brommersma P, Bom N, Linker DT. Multiplane transesophageal echocardiography: latest evolution in an imaging revolution. J AM Soc ECHOCARDIOGR1992;5: 361- 7.
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13. Pandian NG, Hsu TL, Schwartz SL, et al. Multiplane trmasesophageal echocardiography: imaging planes, echocardiographic anatomy, and clinical experience with a prototype phased array OmniPlane probe. Echocardiography 1992;9: 64%66. 14. Castello R, Lenzcn P, Aguirre F, Labovitz AJ. Quantitation of mitral regurgitation by transesophageal echocardiography with Doppler color flow mapping: correlation with cardiac catheterization. J Am Coil Cardiol 1992;19:1516-21. 15. Castello R, Pearson AC, Lenzen P, Labovitz AJ. Effect of mitral regurgitation on pulmonary venous velocitiesderived from transesophageal echocardiography color-guided pulsed Doppler imaging, l Am Coil Cardiol 1991;17:1499-506.
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16. Perry GJ, Helmcke F, Nanda NC, Byard C, Soto B. Evaluation of aortic insufficiencyby Doppler color flow mapping. J Ban Coil Cardiol 1987;9:952-9. 17. Khanderia BK, SewardJB, Oh JK, et al. Value and limitations oftransesophageal echocardiography in the assessmentofmitral valve prostheses. Circulation 1991;83:1956-68. 18. Omoto R, Kyo S, Matsumura M, et al. Evaluation of biplane color Doppler transesophagealeehocardiography in 200 consecutive patients. Circulation 1992;85:1237-47. 19. Thomas JD, Liu CM, FlachskampfFA, O'Shea JP, Davidoff R, IVeyman AE. Quantification of jet flow by momentum analysis: an in vitro Doppler color flow study. Circulation 1990;81:247-59.
Assessment of prosthetic valve regurgitation by echocardiography remains d i ~ o d t . To study the value of the newly introduced multiplane transesophageal technology for this purpose, prosthetic valve regurgitation was examined in 63 consecutive patients with 35 mitral and 33 aortic prostheses (23 bioprostheses and 45 mechanical prostheses). Transvahadar, paravalvular and, in mechanical valves, normal or pathologic transvalvular regurgitation were identified first with 0 degrees (transverse) and 90 degrees (longitudinal)planes combined with flexion of the echoscope tip and then additionally with multiple intermediary planes by transducer rotation. In a subgroup of 20 patients interobserver variability was evaluated. Both methods showed regurgitation in 56 of 68 valves; one additional case of regurgitation was seen by multiplane imaging only. However, 19 cases of regurgitation were not clearly classifiable by biplane transesophageal echocardiography compared with only three with multiplane transesophageal echocardiography. Grading of severity was concordant by both modalities in 66 and discordant in only two cases. Observers disagreed on severity in two of 20 cases based on biplane imaging but in none based on multiplane imaging; classification of regurgitation differed in six of 20 (biplane) and one of 20 (multiplane), respectively. Multiplane transesophageal imaging improves classification of prosthetic regurgitation but has little effect on severity grading. (J AM Soc ECHOCARDIOGR1995;8:70-8.)
Since the advent of Doppler echocardiography it has been increasingly recognized that regurgitation frequently occurs in prosthetic valve replacement. TM This regurgitation can be subdivided into closure backflow occurring during valve closure and leakage backflow occurring as a result of transvalvular or paravalvular leakage after Valve closure, s Almost all mechanical prostheses exhibit a minor degree of normal transvalvular regurgitation even when intact, and bioprostheses develop transvalvular regurgitation in the course of degenerative or infectious changes. However, in vivo differentiation of normal versus pathologic and transvalvular versus paravalvular regurgitation often remains difficult. From the Med Klinik I and the Klinik ffir Herzchirurgie,Thoraxchirurgie trod Gef~a~chirurgie,RWTH Aachen,Germany. Reprint requests: Frank A. Flachskampf,MD, Med. Klinik I, RWTH Aachen, Pauwelsstr. 30, 52057 Aachen, Germany. Copyright9 1995 by the AmericanSocietyof Echocardiography. 0894-7317/95/$3.00 + 0 27/1/56827
70
Transesophageal color Doppler, because of its superb image quality and resolution, can often identify typical patterns of normal leakage backflow that depend on the design of the examined valve. 6-1~Because such patterns can bc complex, multiple cross-sectional planes may be needed for clear understanding of the three-dimensional jet shape. Recently multiplane transesophageal echocardiography T M that is capable of continuous rotation of the cross section from a stable transducer position has been introduced. In this study the value of this technique for the evaluation of prosthetic valve regurgitation was assessed.
METHODS
We studied 63 consecutive patients (age 60 +- 10 years, range 30 to 79 years) with 35 mitral and 33 aortic prostheses (five patients had both mitral and aortic prostheses) who underwent transesophageal
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Table 1 Position and type of examined prosthetic valves Mechanical Mitral prostheses Aortic prostheses
Total no.
Bioprostheses
prostheses
35 (32) 33 (25)
15 (13) 8 (5)
20 (19) 25 (20)
Presence of regurgitation of any type is denoted in brackets.
examination with the multiplanc probe because of clinically suspected prosthetic valve dysfunction, endocarditis, or embolism (Tablc 1). All patients gave written informed consent. Patient files of in-hospital treatment and follow-up visits as well as surgery records were reviewed whcre applicable to detcct whether patients diagnosed as having normal regurgitation had clinical evidence of prosthetic valve failure during the next 2 months and whether surgical findings matched transesophageal echocardiographic diagnoses. Details of the multiplanc cchoscope have been described previously, n Twenty-three bioprostheses (Carpentier-Edwards [American Edwards Laboratories, Irvine, Calif.] and Hancock [Medtronic Inc., Minneapolis, Minn.]) and 45 mechanical prostheses (31 St. Jude Medical [St. Jude Medical, St. Paul, Minn.], 6 Bj6rk-Shiley [Shiley Inc., Irvine, Calif.], 2 Medtronic-Hall [Medtronic Inc.], 2 Duromedix [American Edwards], 2 Starr-Edwards [American Edwards], and 1 Smeloff-Cutter [Cutter Biomedical, San Deigo, Calif.], 1 Sorin [Sorin Biomedica, Saluggia, Italy]) were studied. The vanes were studied: (1) first with only the 0degree and 90-degree plane orientations (corresponding in orientation to the transverse and the longitudinal plane in biplane transcsophageal echocardiography) together with sideward flexion of the echoscope tip, and then (2) with multiple intermediate plane orientations and continuous back-andforth rotation as needed. Color gain settings were not changed when the imaging plane was rotated. The mitral valve was examined from a stable transesophageal transducer position by stepwise rotation of the cross-sectional and color Doppler plane for comprehensive scanning of the whole circumference. To examine aortic prostheses, exact short- and long-axis views (at approximately 60 degrees and 150 degrees, respectively) were obtained. For clarification of shape and origin of aortic regurgitant jets, the imaging plane was rotated back and forth between these views while the echoscope tip was left in place. At both sites special attention was given to definition of the origin of the jet with respect to the
prosthetic valvular ring. To exclude mere closure leakage color Doppler regurgitant jets had to be confirmed by pulsed wave Doppler to be present throughout the part of the heart cycle in which the valve was closed. Regurgitant jets were classified as normal transvalvular regurgitation (in mechanical prostheses), if they followed known normal spatial patterns in number, size, and orientation of jets. 9,1~ They were classified as pathologic transvalvular regurgitation, if the regurgitant jet originated clearly within the valve ring and did not follow patterns of normal transvalvular regurgitation in mechanical valves, or was more than trace in bioprosthetic valves. They were classified as paravalvular regurgitation, if the regurgitant jet originated clearly outside the valve ring. They were classified as regurgitation of uncertain type, if the above criteria were not met. Regurgitation severity was graded visually. In mitral regurgitation, assessment was based on the maximal size of the color jet area or the sum of the maxinlal areas, as previously reported, without normalization for atrial size14; regurgitant jet area less than 3 cm 2 was classified as mild, 3 to 6 cm 2 as moderate, and more than 6 cm2 as severe mitral regurgitation. Additionally, blunted or reversed systolic forward flow in the left upper pulmonary vein had to be present to count regurgitation as moderate or severe.iS In aortic regurgitation, grading relied on the fraction of the outflow tract maximally occupied by regurgitant jet flow during diastole, as previously described for transthoracic echoat; a fraction of less than 25% was classified as mild, 25% to 59% as moderate, and 60% or more as severe. It is recognized, however, that grading of regurgitation severity based on color jet areas is at best semiquantitative and that difficulties are encountered especially when dealing with eccentric jets. In a subgroup of 20 consecutively examined prosthetic valves interobserver variability was analyzed with the following protocol: during image acquisition two-dimensional and color Doppler imaging in the transverse and longitudinal planes only was also recorded on a separate tape. Rotation between transverse and longitudinal planes was not recorded on the additional tape. Tapes containing the full mul-
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Figure 1 Normal regurgitation in St. Jude Medical valves. A, Schematic drawing of normal pattern of leakage backflow occurring through closed valve, viewed from two perspectives. Reproduced with permission from the American College of Cardiology. 9 B, Example of predicted pattern in mitral prosthesis imaged in two orthogonal but intermediate (neither transverse nor longitudinal) planes (le#, 30 degrees, right, 115 degrees). LA, Left atrium.
tiplane examination and those containing only biplane recordings were reviewed in a random order by two experienced echocardiograpbers. RESULTS
No complications or failures occurred with the mnltipiane echoscope. Biplane and muitipiane technique diagnosed the presence of leakage in a similar number of valves: 56 of 68 with biplane and 57 of 68 with multiplane transesophageal echocardiography. The additional case was a small paravalvular leak in a mitral prosthesis not seen with the biplane approach. Classification o f Regurgitation Type
Multiplane examination in the described fashion allowed a better definition of regurgitation type. By the biplane approach, in 19 of 56 prostheses showing regurgitation, the type of regurgitation was not
clearly defined; in contrast, in only three cases (all in the aortic position and all of mild severity) the type of regurgitation remained unclear after multiplane examination. O f these 19 cases 11 were aortic, and eight were mitral prostheses; five were bioprostheses, and 14 were mechanical valves. Multiplane transesophageal examination identified these cases as normal transvalvular only (six); paravalvular only (five); pathologic transvalvuiar only (four); normal transvalvular and paravalvular (one); paravalvular and pathologic transvalvular (one); and unclear (three). As expected the two examined Starr-Edwards valves did not show transvalvular leakage. The findings are summarized in Table 2. Better definition of regurgitation type was possible by (1) improving the recognition of normal patterns, for instance, the complex pattern of bileaflet prostheses (Figure 1) or the typical peripheral symmetric jets in tilting disc prostheses (Figure 2); (2) allowing the examiner to choose an optimal intermediate cross-sectional plane to define the origin of
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Figure 2 Symmetric, peripheral normal transvalvular regurgitation in Bj6rk-Shiley CC mitral prosthesis occurring between valve ring and occluding disk, imaged in intermediate (45 degrees) plane. LV, Left ventricle; RA, right atrium.
Table 2 Classification of type and severity of regurgitation in 68 valve prostheses by biplane and multiplane transesophageal echocardiography Regurgitation
Biplane
Multiplane
Type Normal transvalvular Pathologic transvalvular Paravaivular Uncertain type
23 7 9 19
30 11 18 3
Severity N o regurgitation Mild regurgitation Moderate Severe
12 35 15 6
11 35 15 7
Numbers indicate prostheses in which regurgitation was found. Note that in some prostheses two types of regurgitation were found (two cases by biplane and five cases by multiplane examination).
a regurgitant jet outside or inside the prosthetic valve ring (examples of pathologic regurgitation are displayed in Figures 3 to 6); and (3) enabling the examiner to rotate the viewing plane back and forth without echoscope tip motion to follow the spatial course of a jet (Figures 3, 6). No patient diagnosed as having normal regurgitation had a clinical course during the next 2 months suggesting severe regurgitation or necessitating angiography or surgery. In nine patients o f our study group surgery was performed. Six patients had a diagnosis of severe
transvalvular regurgitation; surgery confirmed massive degenerative lesions in five bioprostheses, including one with a flail leaflet, and in one case thromboric immobilization of a Bj6rk-Shiley prosthesis occurred. Severe paravalvular regurgitation was diagnosed before the operation in two patients, and the location o f the paravalvular leaks (at the lateral mitral circumference and in the noncoronary sinus o f Valsalva) was confirmed at surgery. One patient with a mitral St. Jude Medical prosthesis was operated on because of embolizing endocarditis; transesophageal echocardiography had shown only nor-
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Figure 3 Paraval~allarleak in St. Jude Medical aortic valve prosthesis. Left, long-axis view at 125 degrees; right, short-axis view at 45 degrees. Note that origin and (in short axis) course of paravalvular leakage can be located outside ring of prosthesis. AOA, Ascending aorta; AVR, aortic valve replacement. mal transvalvular regurgitation, and no leak or dehiscence of the prosthesis was observed during the operation.
Grading of Regurgitation Severity Grading of regurgitation showed little diffcrence between the biplane and the multiplane approach. Apart from the one cited paravalvular leak not seen by biplane examination, one case of regurgitation in a mitral bioprosthesis was graded moderate by biplane and severe by multiplane examination, and regurgitation in one mechanical mitral prosthesis was graded mild by biplane and moderate by multiplane examination. Grading is summarized in Table 2.
Interobserver Variability
Figure 4 Paravalvular leak in St. Jude Medical mitral prosthesis. Origin of jet is recognizable in 37-degree plane (arrows). Note also small normal transvahaflar regurgitation jets.
Thc two independcnt observers differcd with regard to severity of regurgitation in 2 of 20 cases (10%) when evaluating biplane images only (in both cases one observer graded regurgitation as mild, the othcr as moderatc); they had complete accordance (20 of 20) when cvaluating severity by multiplane recordings. The differences between classification of type of regurgitation were as follows: on thc basis of thc biplane recordings classification differcd in 6 of 20 cases (30%). In these cases one observer diagnosed paravalvu]ar leakage in all six valves, whereas thc other diagnosed unclear type of regurgitation twice, paravalvular leakage and additional normal transvalvular regurgitation twice, pathologic transvalvular re-
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Figure 5 Transvalvular regurgitation in mitral bioprosthesis. Left, at 0 degrees, one central regurgitant jet is seen, but image of origin is not obtained in this plane. Right, in intermediate plane (52 degrees), two distinct transvalvular regurgitant jets, one central and one eccentric, are seen. They originate within valve ring. gurgitation once, and normal regurgitation only once. In contrast, based on the multiplane examinations only one ( 5 %) case of disagreement occurred, where one observer diagnosed a paravalvular leak, and the other diagnosed paravalvular and normal transvalvular leakage.
DISCUSSION Background Prosthetic regurgitation can be classified as closure backflow, occurring with the closure of the valve occluder or bioprosthetic leaflets; and leakage backflow, taking place after the valve is shut. s It has been shown that except for the Starr-Edwards ball-in-cage valve, all mechanical valves by design exhibit some degree of leakage backflow, often at the hinge points of the occluder (as in the St. Jude Medical bileaflet valve) (Figure 1), or around a central strut (as in the Medtronic-Hall valve), or between valve ring and central occluder (as in the Bj6rk-Shiley valve) (Figure 2). 9H Bioprostheses in vivo also often show transvalvular leakage of varying degree, most likely caused by degenerative changes, a,4 Another type of prosthetic valve regurgitation is paravalxaflar leakage, which has been recognized to occur quite frequently, and which especially in mechanical prostheses is difficult to distinguish from peripheral transvalvular leakage.
Prosthetic regurgitation patterns are identified par, ticularly well by transesophageal color Doppler because of its excellent image quality and spatial resolution. Initial studies used monoplane echoscopes,6-8 but monoplane transesophageal echocardiography provides only a limited array of cross-sectional planes even with the sideward flexion of the echoscope tip. Furthermore complete examination of mitral prostheses requires a pullback of the instrument from the gastroesophageal junction, where almost a frontal short-axis view of the prosthesis is obtained, to the high transesophageal position, where a horizontal transverse cross-section is imaged. Thus the angle between mitral prosthesis ring plane and the imaging sector changes continuously during this procedure, as does the transducer position, making spatial orientation difficult for the examiner. In aortic prostheses precise short- and long-axis views often are difficult to obtain with monoplane instruments. Recently biplane echoscopes have enhanced the diagnostic capabilities, and the value of biplane transesophageal echocardiography, especially in the assessment ofmitral regurgitation, has been shown.17,18 However, the planes acquired with these instruments have different spatial origins, because longitudinal and transverse transducers constitute two separate element sets, and because intermediate planes require sidewards flexion of the tip that houses the two transducers. Thus understanding of complex spatial relationships remains difficult for the examiner. Fur-
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Figure 6 A, Regurgitation in mitral bioprosthesis. Transverse (0 degrees, left) and longitudinal (90 degrees, right) cross-sections fail to identify precise origin with respect to valve ring. B, Intermediate planes visualize origin and course of one paravalvular (137 degrees, left) and one eccentric transvalvular (70 degrees, right) jet. LAA, Left atrial appendage.
thermore use of the sideward flexion sometimes is unpleasant for the patient. Multiplane transesophageal echocardiography constitutes the latest innovation in this field, H-x3providing complete and easy access to intermediary cross-sections without the need for change of transducer position and thus without shift in the imaging sector origin. Clinical Significance o f the Present Study
Because grading of regurgitation by the size of color Doppler jet areas has well-recognized limitations and
can be misleading, 19 identification of regurgitant jet origin and of typical regurgitant jet patterns is an important issue for the distinction between pathologic and normal conditions. Because normal transvalvular regurgitation in mechanical valves often originates eccentrically, for example in the St. Jude Medical bileaflet prostheses, differentiation from paravalvular leakage is particularly difficult if the optimal imaging plane cannot be achieved or maintained to define whether the jet originates inside or outside the sewing ring of the prosthesis.
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The unique ability of the mukiplane transducer to obtain multiple cross-sections from a single stable transducer position allows easier and more confident diagnosis of the type of prosthetic regurgitation. Moreover this technique almost obviates the need for lateral flexion of the echoscope tip. In our experience with this technique only minimal lateral adjustments, mostly to improve contact with the esophageal wall, were required. Although only one case of regurgitation was completely missed with biplane transesophageal echocardiography, in 16 of 56 valves the type of regurgitation was clarified only with the multiplane technique. In contrast only small differences were seen in grading of severity; multiplane examination led to an upgrade by one step in the two discordant cases. The main value of this technique therefore is not higher sensitivity or better semiquantitation of regurgitation but the improved classification of type, especially in cases with mild or moderate regurgitation. Another important finding is that observers agreed more on classification and grading based on multiplane rather than on biplane examinations, confirming that multiplane examination defined regurgitation more clearly. Limitations
Classification of regurgitation in this study is based on thc examiner's expertise, and no independent gold standard is offered. Furthermore grading of severity based on color jet area has well-known limitations, especially when assessing aortic prosthetic regurgitation from a transesophageal window, where shadowing is an additional drawback. However, there is presently no technique as sensitive for the detection of prosthetic valve regurgitation as transesophageal echocardiography that could serve as an independent standard. In the nine patients who had surgery, the transesophageal findings were confirmed, and in the patients classified as having normal regurgitation the clinical course showed no evidence contradicting this classification. Another important drawback of this study is that comparison of biplane and multiplane technique was not based on separate examinations and examiners, because this was not deemed ethically justified in the awake patient. To partially circumvent this problem we analyzed interobserver variability in a subgroup by using different tapes for the two parts of the examination and reviewing them in a blinded fashion. The lower variability found for multiplane examination indicates better definition of prosthetic regurgitation by this technique.
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Conclusion
Multiplane transesophageal echocardiography clarifies the spatial relationships between valve ring and jet origin and course and thus improves classification of the type of prosthetic regurgitation. Grading of regurgitation, however, is only marginally affected by this technique. The authors thank James D. Thomas, MD, Cleveland, for
review of and thoughtful advice on this manuscript.
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