Intraoperative transesophageal color-coded Doppler echocardiography for evaluation of residual regurgitation after mitral valve repair

J THORAC CARDIOVASC SURG 1990;100:756-61

Intraoperative transesophageal color-coded Doppler echocardiography for evaluation of residual regurgitation after mitral valve repair Because mitral valve competence after mitral valve reconstruction is awkward to assess during this procedure, we evaluated in tbis respect transesopbageal color-coded Doppler echocardiography in 23 patients undergoing mitral valve reconstruction for severe mitral regurgitation. Transesopbageal echocardiographic examinations were performed after induction of anesthesia but before sternotomy (baseline~ after mitral valve repair before decannulation, and at sternal closure, aD at similar mean aortic pressure and echocardiographic instrument settings. The degree of mitral regurgitation by transesopbageal color Doppler flow mapping was visually quantified on a 5-point scale (0 to 4~ pending the left atrial extent of the regurgitant jet. Tbis was compared with the degree of mitral regurgitation by left ventricular cineangiography performed within several weeks after operation and also visually quantified on a 5-point scale (0 to 4~ with use of the right anterior oblique projection. There was good correlation between the two methods (r = 0.83; p < 0.001). We conclude tbat residual mitral regurgitation, as assessed by transesopbageal color flow mapping in the operating room, highly correlates with the ultimate mitral regurgitation by cineangiography. Therefore transesophageal echocardiography can be helpful for evaluation of mitral valve competence during mitral valve recoltitruction, and hence, in case of repair failure, aDow valve replacement in the same surgical session, thus avoiding reoperation.

Stan L. A. Reichert, MD, Cees A. Visser, MD, F ACC, Ad C. Moulijn, MD, Maarten J. Suttorp, MD,a Renee B. A. v.d. Brink, MD, Jacques J. Koolen, MD, Wybren Jaarsma, MD,a Fred Vermeulen, MD,a and Arend J. Dunning, MD, FACC, Amsterdam, Nieuwegein, and Utrecht, The Netherlands

Mitral valve repair is preferable to mitral valve replacement whenever technically possible, because valve repair has shown lower short-term morbidity and mortality, 1.2 stable long-term results, 3•4 and better left ventricular function, probably because of the tethering effect of papillary muscles and chordae. 5 Residual mitral regurgitation after valve repair, however, still remains a problem, because of its increased From the Department of Cardiology and Cardiac Surgery, Academic Medical Center, Amsterdam, Antonius Hospital Nieuwegein,• and the Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands. Received for publication June 2, 1989. Accepted for publication Nov. 30, 1989. Address for reprints: C. L. A. Reichert, MD, Department of Cardiology, Academic Medical Center, Meibergdreef9, I I OS AZ Amsterdam, The Netherlands.

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postoperative morbidity and mortality and need for early reoperation to replace the valve in case of severe incompetence. Several surgical intraoperative techniques to evaluate residual mitral regurgitation have been described,6· 7 but none of these methods appears to be ideal. Intraoperative epicardial echocardiography with contrast or color flow imaging has been applied recently with promising results, but interferes with the surgical procedure. 8• 13 We therefore undertook the present study to determine the value of transesophageal color-coded Doppler echocardiography during mitral valve repair. Methods

Patient population. From January 1988 to March 1989 23

patients underwent mitral valve reconstruction. All but one had severe mitral regurgitation as determined by both echocardiography and left ventricular cineangiography; mitral regurgitation was caused by chordal rupture (14 patients), mitral valve prolapse (five patients), and isolated annular dilatation (three

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Fig. 1. Diagram illustrating degree of mitral regurgitation, as assessed by transesophageal echocardiography {TEE) and .preoperative left ventricular cineangiography (ANGlO). patients). One patient had moderate mitral insufficiency, but severe mitral stenosis. There were 10 women and 13 men with a mean age of 61 years (range 18 to 81 years). Verbal informed consent was obtained from all patients. Transesophageal echocardiography. Two-dimensional echocardiographic and color Doppler flow examinations were performed with a commercially available 5 MHz transducer, mounted on the distal end of an endoscope and interfaced with a phased-array imaging system (77020 CF, Hewlett-Packard Co., Palo Alto, Calif.). In this system flow directed to the transducer is displayed as red and flow away from the transducer as blue. If the flow velocity exceeds the Nyquist limit, color reversal occurs (aliasing); in case of turbulent flow, green is added to red or blue, giving a mosaic pattern. At diagnostic depths of 8 to 12 em, the frame rate was 12 to 16 frames/ sec. Since gain levels influence the extent of a regurgitant area, color flow gain was increased to just below the level at which background noise was seen. 14 Gain setting, Nyquist limit, and filter settings were not changed after baseline echocardiograms had been taken. All studies were recorded on VHS videotape for later analysis by two independent cardiologists who did not have knowledge of the angiograms. The echoscope was blindly inserted into the esophagus, but with laryngoscopic control when necessary, after induction of anesthesia. Because depression of myocardial function may occur directly after induction of anesthesia and intubation, echocardiographic preoperative baseline values were obtained at least 20 minutes after intubation, 9 but before sternotomy and cannulation, since these procedures may increase afterload. 10 Mitral regurgitation was graded semiquantitatively on a 5-point scale (0 to 4) in one of the mitral valve views 11 • 12 ; the

jet area, in relation to the left atrial cavity, included the turbulent central core, displayed as a mosaic pattern, as well as the adjacent laminar flow (red) moving simultaneously with the regurgitant jet and in the same direction; grade 0 means no mitral regurgitation, grade 1 is assigned if the regurgitant jet is observed just above the mitral valve (less than 1 em), grade 2 if the regurgitant jet extends up to one third of the left atrial area, grade 3 if it extends up to two thirds, and grade 4 if it extends more than two thirds into the left atrium. 13• 16 The left atrium was searched for eccentric regurgitant jets by moving the echoscope from the roof of the left atrium to the bottom, with an almost transgastric approach. This also enabled us to get a three-dimensional impression of the extent of the regurgitant jet. Care was taken not to confuse pulmonary venous inflow with mitral regurgitation, by following the flow signal to its origin (pulmonary vein respectively mitral valve). After left atrial closure and partial rewarming, cardiopulmonary bypass was stopped and the degree of mitral regurgitation was again estimated in the beating heart, with either sinus- or atrial-paced rhythm, as described previously, when baseline aortic pressure had been achieved. Then cardiopulmonary bypass was reinstituted and the patient was weaned from bypass in the usual manner and decannulated. Before sternum closure, a complete echocardiographic examination was again performed, including grading of mitral regurgitation at baseline aortic pressure. Surgical procedure. After median sternotomy and institution of cardiopulmonary bypass, the surgical procedure was performed (excision of the part of the valve with ruptured chordae (14 patients), or annuloplasty with a Carpentier ring, or both (II patients), or a Puig-Massana ring (12 patients). One

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Fig. 2. Schematic diagram illustrating degree of mitral regurgitation before and after mitral valve reconstruction, as assessed by transesophageal echocardiography. patient also had open commissurotomy. In four patients additional coronary artery bypass grafting was performed. Left ventricular cineangiography. All patients underwent left ventricular cineangiography, usually 2 to 8 weeks before operation. All but two patients underwent postoperative left ventricular cineangiography within 3 weeks after operation (the other two patients after 8 weeks). The severity of mitral regurgitation was assessed semiquantitatively (by a cardiologist who was blinded for the echocardiographic results) with the atrial opacification in the 30-degree right anterior oblique view. 17 Statistical methods. Agreement between grading of mitral regurgitation with transesophageal color-coded Doppler flow imaging and cineangiography was assessed by a Spearman rank correlation test. Results In all patients echocardiograms adequate for analysis were obtained and there were no complications associated with the procedure. Preoperative (baseline) mitral regurgitation. Degree of mitral regurgitation assessed by preoperative cineangiography and transesophageal echocardiography (obtained at least 20 minutes after intubation) is shown in Fig. 1. There was good agreement on severity of valve incompetence between the two methods. Mitral regurgitation immediately after repair. Degree of mitral regurgitation immediately after mitral

valve repair, determined at baseline aortic pressure and echo instrument settings, was compared with degree of preoperative mitral regurgitation. As shown in Fig. 2, all but two patients showed a decrease of mitral regurgitation. These two patients, one with mitral stenosis and insufficiency and the other with a chordal rupture, had severe mitral insufficiency, as assessed by transesophageal echocardiography. The surgeon, however, after fluid filling of the arrested heart by an apical vent from the cardioplegia line at a controlled pressure, considered the reconstruction satisfactory. Both patients had severe left-sided heart failure postoperatively and were reoperated on within 6 months for prosthetic valve implantation. Mitral regurgitation at sternal closure. The degree of mitral regurgitation as assessed just before sternal closure was compared with the degree of valve incompetence immediately after repair and before decannulation. As shown in Fig. 3, the degree of mitral regurgitation was the same except for one patient. This patient, immediately after repair, had moderate to severe regurgitation (grade 3) because of transient ischemia as documented by ST segment elevation, and, later on, at sternal closure, grade 2. Postoperative mitral regurgitation. Degree of postoperative mitral regurgitation was assessed by cineangiography in all but two patients within 3 weeks (the two others after 8 weeks) and compared with degree of mitral regurgitation as assessed by transesophageal echocardiography obtained immediately after repair imd before decannulation (Fig. 4). This yielded a correlation coefficient of 0.83 (p < 0.001). Discussion Repair procedures of the mitral valve for valvular incompetence have been increasingly used by. surgeons as 1 18 a result of the favorable outcome in several series. -4, The complex surgical procedure has a significant learning curve, which urges for a reliable method to estimate residual mitral regurgitation intraoperatively. In case of severe valvular incompetence, it would be possible to continue with valve replacement during the same procedure. Several surgical and hemodynamic measurements have been described for assessment of residual mitral regurgitation, like fluid filling of the arrested heart, palpation of the regurgitant jet in the left atrium or V wave in left atrial pressure curve, but none appeared to be ideal.6· 7, 1s Maurer 13 and Czer 15 and their co-workers reported that fluid filling of the arrested heart may lead to both

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Fig. 3. Diagram illustrating the relation between mitral regurgitation after mitral valve repair and before decannulation (post-repair) and at sternal closure.

r=0.83 (p<0.001)

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Fig. 4. Degree of mitral regurgitation as assessed by transesophageal echocardiography after mitral valve reconstruction and before decannulation (TEE) and by postoperative left ventricular cineangiography (ANGlO).

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underestimation and overestimation of severity of mitral regurgitation compared with epicardial color Doppler flow mapping in the beating heart. This is no surprise, because two important determinants of mitral valve closure, that is geometry of the left ventricle during systole and contraction of the ventricular wall at the base of the papillary muscle, are neglected by testing mitral valve competence in the arrested heart. Goldman and co-workers8 recently described intraoperative epicardial echocardiography, since this approach allows multiple tomographic imaging planes of both valvular and subvalvular structures as chordae tendineae and papillary muscles. Using left ventricular contrast injection, they found a sensitivity of 100% and specificity of 90% for the detection of mitral regurgitation. More recently Czer 13 and Maurer 15 and their coworkers avoided the disadvantages of contrast echocardiography, such as puncture of the left ventricle and hence interference with papillary muscles and chordae tendineae and the risk of air emboli, by using epicardial Doppler color flow mapping. They demonstrated that this technique also has a high sensitivity (94%) and specificity (93%) for detection of mitral regurgitation, but still interferes with the surgical procedure. Dahm and co-workers 19 performed transesophageal echocardiography with left ventricular contrast injection in 19 patients undergoing mitral valve reconstruction, but did not compare their results with residual mitral regurgitation by cineangiography to validate their method. In addition, there still was the disadvantage of left ventricular puncture. We combined transesophageal echocardiography with color Doppler flow mapping, which does not interfere with the surgical procedure and does not need contrast injection with its inherent problems, and compared it with residual mitral regurgitation by cineangiography. In this respect, however, it is important to emphasize that both cineangiography and Doppler echocardiography give at best a semiquantative estimate of the actual regurgitant volume, and each has its own limitations. Cineangiography, the golden standard until now for grading of insufficiency, is influenced by catheter position and rhythm disturbances during contrast injection and shows considerable overlap of the regurgitant volume between grades of insufficiency. 20 On the other hand, with Doppler echocardiography, although a jet area extends with increasing regurgitant volume, it is also dependent on driving pressure, size, and shape of the regurgitant orifice, compliance of left atrium, merging of the jet with sometimes turbulent pulmonary venous inflow and echo instru-

ment settings (i.e., gain setting, transducer frequency, and pulse repetition frequency). In addition, with the transesophageal approach, one is confined to a limited number of tomographic imaging planes because of the narrow space available for transducer manipulation in the esophagus. Nevertheless, it is possible to differentiate between mild and severe residual mitral insufficiency. When severe mitral regurgitation, as assessed by transesophageal color-coded flow imaging, is found, the mitral valve repair procedure is unsuccessful and the valve can be replaced by a prosthesis during the same surgical session. In our patient group, severe residual mitral regurgitation was found in two patients, but the valve was not replaced in the same surgical procedure because the value of transesophageal echocardiography in assessment of residual mitral regurgitation was not validated yet, and, with conventional fluid filling of the arrested heart, repair seemed satisfactory to the surgeon. Thus, despite limitations, intraoperative transesophageal echocardiographic color flow imaging provides a rapid, fairly accurate assessment of mitral competence in the operating room immediately after valve repair and may be helpful to avoid reoperation with its associated increased morbidity and mortality.

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REFERENCE S Orszulak TA, Schaff HV, Danielson GK, eta!. Mitral regurgitation due to ruptured chordae tendineqe. J THORAC CARDIOVASC SURG 1985;89:491-8. Yacoub M, Halim M, Radley-Smith R, McKay R, Nijveld A, Towers M. Surgical treatment of mitral regurgitation caused by floppy valves: repair versus replacement. Circulation 1981 ;64:210-6. Carpentier A, Chauvaud S, Fabiani, eta!. Reconstructive surgery of mitral valve incompetence: ten-year appraisal. J THORAC CARDIOVASC SURG 1980;79:338-48. Carpentier A. Cardiac valve surgery-the "French correction." J THORAC CARDIOVASC SURG 1983;86:323-37. Bonchek LI, Olinger GN, Siegel R, Tresch DD, Keelan MH. Left ventricular performance after mitral reconstruction for mitral regurgitation. J THORAC CARDIOV ASC SURG 1984;88: 122-7. Charlesworth DC, Weisel RD, Baird RJ, Scully HE, Goldman BS. Assessment of mitral and tricuspid competence after valvuloplasty. Ann Thorac Surg 1983;35: 104-7. Ferguson TB, Wechsler AS. Testing of mitral valve competence following combined mitral valve repair and aortic valve replacement. Ann Thorac Surg 1985;40:631-2. Goldman ME, Fuster V, Guarino T, Mindich BP. Intraoperative echocardiography for the evaluation of valvular regurgitation: experience in 263 patients. Circulation 1986;74:143-9.

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9. Giles R, Berger H, Barash P. Continuous monitoring of left ventricular performance with computerized nuclear probe during laryngoscopy and intubation before coronary artery bypass grafting. Am J Cardia! 1982;50:735-41. I 0. Van W ezel H B, Borill JG, Schuller J C, Gielen J, Hoeneveld MH. Comparison of nitroglycerin, verapamil and nifedipine in the management of arterial pressure during coronary artery surgery. Br J Anaesth 1986;58:267-73. II. Seward JB, Khandheria BK, Oh JK, eta!. Transesophageal echocardiography: technique, anatomic correlations, implementation and clinical applications. Mayo Clin Proc 1988;63:649-80. 12. Visser CA, Koolen JJ, VanWezel HB, Dunning AJ. Transesophageal echocardiography: technique and clinical applications. J Cardiothorac Anesth 1988;2:74-91. 13. Maurer G, Czer LSC, Chaux A, eta!. Intraoperative Doppler color flow mapping for assessment of valve repair for mitral regurgitation. Am J Cardioll987;60:333-7. 14. Miyatake K, Izumi S, Okamoto M, eta!. Semiquantitative grading of severity of mitral regurgitation by real time twodimensional Doppler flow imaging technique. J Am Coli Cardia! 1986;7:82-8.

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15. Czer LSC, Maurer G, Bolger AF, et a!. Intraoperative evaluation of mitral regurgitation by Doppler color flow mapping. Circulation 1987;76:108-16. 16. Heincke F, Nanda NC, Hsiung MC, eta!. Color Doppler assessment of mitral regurgitation with orthogonal planes. Circulation 1987;75: 175-83. 17. Sellers RD, Levy MJ, Amplatz K, Lillehei CW. Left retrograde cardioangiography in acquired cardiac disease: technique, indication and interpretations in 700 cases. Am J Cardia! 1964; 14:437. 18. Sand ME, Naftel DC, Blackstone EH, Kirklin JW, Karp RB. A comparison of repair and replacement for mitral valve incompetence. J THORAC CARDIOVASC SURG 1987; 94:208-19. 19. Dahm M, Iversen S, Schmid FX, Drexler M, Erbel R, Oelert H. Intraoperative evaluation of reconstruction of the atrioventricular valves by transesophageal echocardiography. Thorac Cardiovasc Surg 1987;35:140-2. 20. Croft ChH, Lipscomb K, Mathis K, et a!. Limitations of qualitative angiographic grading in aortic and mitral regurgitation. Am J Cardia! 1984;53:1593-8.

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