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Transesophageal Echocardiographic Guidance of Closed Mitral Commissurotomy
Transesophageal Echocardiographic Guidance of Closed Mitral Commissurotomy Gerald I. Cohen, MD, Paul N. Casale, MD, Bruce W. Lytle, MD, and James D. Thomas, MD, Cleveland, Ohio
We describe the utility of transesophageal echocardiography in a patient undergoing emergent closed mitral commissurotomy. Two-dimensional images provided an assessment of valve morphology and mobility while Doppler echocardiography was used to monitor the occurrence of mitral regurgitation and changes in valve gradient and area. (J AM Soc ECHOCARDIOGR 1993;6:332-4.)
T
ransesophageal echocardiography is useful to monitor and guide percutaneous balloon mitral valvuloplasty. It allows assessment of mitral valve morphology and detection of left atrial clot and mitral regurgitation. 1•2 Although percutaneous balloon mitral valvuloplasty and open mitral valve reconstruction have largely supplanted closed mitral commissurotomy, this older technique is still performed to alleviate mitral stenosis when cardiopulmonary bypass is not readily available. 3 This article describes the application of transesophageal echocardiography during closed commissurotomy in a patient who was in shock and had severe pulmonary hypertension.
CASE REPORT
A 44-year-old woman with known mitral stenosis was admitted to a local hospital with fever, cough, and increasing dyspnea. During the next 48 hours, her condition worsened in spite of antibiotic treatment for suspected pneumonia. Respiratory failure and hypotension ensued and she was transferred emergendy to the Cleveland Clinic while receiving dopamine, dobutamine, and norepinephrine bitartrate (Levophed). On arrival, she was comatose and anuric with a heart rate of 116 beats I min and a systolic blood pressure of 50 mm Hg. Diffuse rales in both lung fields obscured heart sounds. Her extremities were cool and without edema. A chest x-ray film showed diffuse pulmonary infiltrates. Hypotension was treated with placement of an intraaortic balloon
From the Department of Cardiology and Cardiothoracic Surgery of The Cleveland Clinic Foundation. Reprint requests: Gerald 1. Cohen, MD, The Cleveland Clinic Foundation, Department of Cardiology F-15, 9500 Euclid Ave., Cleveland, OH 44195. Copyright © 1993 by the American Society of Echocardiography. 0894-7317/93 $1.00 +.10 27/1/44118
332
pump and increased Levophed infusion. A transesophageal echocardiogram (Hewlett Packard Sonos 1000, Andover, Mass.) revealed severe mitral stenosis without regurgitation, mean gradient of 18 mm Hg, and a valve area of 0.5 cm2 (pressure half-time = 418 msec) (Figure 1, A). Spontaneous contrast without thrombus was present in the severely dilated left atrium. Although the left ventricle was small and hyperdynamic, the right ventricle showed severe dilatation and dysfunction. No tricuspid regurgitation was present; however, Swan-Ganz catheter (Baxter Healthcare Corp., Santa Ana, Calif.) measurements revealed a pulmonary artery pressure of 102/48 mmHg. Percutaneous balloon mitral valvuloplasty was deferred because of concern that the high right-sided pressures might cause significant right-to-left shunting through a punctured interatrial septum with resulting hypoxemia. 4 In face of her severe hemodynamic instability, she was rushed to the operating room and a closed mitral commissurotomy was performed. A Tubbs dilator was placed into the left ventricle through an apical incision and was guided between the mitral leaflets by the surgeon's finger in the left atrium via an appendage incision (Figure 1, B). The valve area was assessed by surgical palpation and continuous wave Doppler after each of two dilatations of the mitral orifice (Figure 1, C). With the second dilatation, the mean Doppler gradient fell to 6 mm Hg and valve area increased to 3.0 cm2 (pressure half-time = 73 msec) (Figure 1, D). Transesophageal imaging showed improved leaflet mobility without mitral regurgitation and significandy improved right ventricular function. Cardiac index increased from 1 LI mini m 2 before surgery to 3 L/min/m2 after. However, pulmonary artery pressure remained high and did not fall until several days later. The postoperative course was complicated by severe encephalopathy, renal failure, bacteremia; respiratory distress syndrome, and thrombocytopenia.
Journal of the American Society of Echocardiography Volume 6 Number 3 Part 1
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Figure 1. Transverse four-chamber transesophageal views. A, Severe mitral stenosis before commissurotomy with small left ventricle (LV) and enlarged right ventricle (R V). Significant subvalvular thickening and stenosis, with relatively mild calcification, was present. B, Tubbs dilator (arrows) has passed between leaflets and is visible in the left atrium. C, After commissurotomy, the valve and subvalvular apparatus appear less stenosed. D, Intraoperative comparison of continuous wave Doppler profile of transmitral velocity before (above) and after (below) commissurotomy where a reduced gradient and shorter pressure half-time are apparent. Arrow indicates scale marker of 2 m/sec. RA, Right atrium; LA, left atrium.
Two weeks after surgery, a transthoracic echocardiogram demonstrated mild mitral stenosis with a valve area of 1. 7 cm2 and a mean gradient of 6 mm Hg (pressure half-time = 126 msec). The patient left the intensive care unit on the sixtieth postoperative day and was discharged home 2 weeks later neurologically intact. Since her discharge, she has had an uneventful clinical course and has resumed her normal activities.
DISCUSSION
The reported case posed an urgent and extraordinary management dilemma. In face of severe pulmonary hypertension and systemic hypotension, immediate
relief of severe mitral stenosis was essential. Utilization of cardiopulmonary bypass in this situation would have rapidly stabilized her hemodynamic status and allowed for a more refined open commissurotomy. However, patients with severe pulmonary hypertension who undergo mitral surgery may not be weanable from cardiopulmonary bypass after surgery because of bypass-associated worsening of right ventricular function and pulmonary hypertension. 5 We believed that our patient was at high risk of this complication because of severe right ventricular dysfunction, sepsis, and pneumonia. Closed mitral commissurotomy offered an expeditious and definitive (though unorthodox) solution to a dire situation. Transesophageal echocardiography was extremely useful in this patient's management. Before surgery,
Journal of the American Society of Echocardiography May-June 1993
334 Cohen et at.
knowledge of the mitral valve's morphologic condition (valve mobility and valvular and subvalvular calcification)6 and lack of regurgitation indicated that a closed mitral comissurotomy would be feasible. During surgery, transesophageal imaging allowed the surgeon to proceed aggressively with the knowledge that dilatation of the valve was not causing valvular regurgitation. The option of transesophageal continuous wave Doppler was particularly useful as it permitted preoperative and intraoperative measurement of the valve gradient and area allowing confirmation that the valvotomy was adequate despite the fact that the pulmonary artery pressure remained very elevated. It was observed that the pressure half-time increased significantly between the immediate and 2week postoperative assessment, suggesting reduction in valve area. Chan and Suchowske have shown that transesophageal measurement of mitral pressure halftime correlates well with transthoracic observations. It has been shown,8 however, that the sudden changes in atrioventricular compliance and transmitral pressure gradient that accompany acute valvotomy render the pressure half-time method unreliable in this setting. This may explain in part the discrepancy in mitral valve area observed immediately after commissurotomy and 2 weeks later. Although mitral pressure half-time is considered a pure inverse measure of mitral valve area, it additionally varies directly with the net compliance of the atrium and ventricle and with the square root of the transmitral pressure gradient. 8 In the current case, the pressure gradient fell threefold and atrial compliance likely increased as it was decompressed, whereas ventricular compliance likely fell with the sudden volume loading of the chronically underfilled ventricle. It is thus not surprising that the mitral pressure half-time seemed to be shortened initially out of proportion to the acute increase in valve area. Of note, Chen et al. 9 demonstrated in 18 patients that the pressure halftime method overestimates mitral valve area immediately after valvuloplasty but regains accuracy within 48 hours; the increase in pressure half-time in our case at 2 weeks appears consistent with this observation, although actual recoil of the mitral orifice may have also played a role. In contrast, the fall in pulmonary arterial pressure is not a likely cause of this change because pulmonary hypertension has been shown not to affect Doppler measurements of pressure half-time. 10 An attractive alternative to the pressure half-time assessment of mitral valve area is direct planimetry of the orifice from a short-axis image of the valve. 11 Unfortunately, in the current case, both biplane
transesophageal echocardiographic views were oblique to the orifice. In fact, we have found that a perfect short-axis view of the mitral valve is obtainable in only about 40% of patients during singleplane transesophageal echocardiography.12 Epicardial and multiplane transesophageal echocardiography should be superior alternatives for planimetry of the mitral valve orifice. In spite of these limitations, however, transesophageal echocardiography facilitated the emergent care of our patient and was particularly useful in determining that an adequate commissurotomy had been accomplished. We thank Jody Karabinus for secretarial assistance. REFERENCES 1. Jaarsma W, Visser CA, Suttorp MI, Haagen FDH, Ernst SMPG. Transesophageal echocardiography during percutaneous balloon mitral valvuloplasty. J AM Soc ECHOCARDIOGR 1990;3:384-91. 2. Lock JE, Khalilullah M, Shrivastava S, Bahl V, Keane JF. Percutaneous catheter commissurotomy in rheumatic mitral stenosis. N Engl J Med 1985;313:1515-8. 3. Cohn LH, Allred EN, Cohn LA, Disesa VI, Shemin RJ, Collins JJ. Long-term results of open mitral valve reconstruction for mitral stenosis. Am J CardioI1985;55:731-4. 4. Goldberg N, Roman CF, Cha SD, et al. Right to left interatrial shunting following balloon mitral valvuloplasty. Cathet Cardiovasc Diagn 1989;16:133-5. 5. D'Ambra MN, LaRaia PI, Philbin DM, Watkins WD, Hilgenberg AD, Buckley MJ. Prostaglandin El, a new therapy for refractory right heart failure and pulmonary hypertension after mitral valve replacement. J Thorac Cardiovasc Surg 1985;89:567-72. 6. Wilkins GT, Weyman AE, Abascal VM, Block PC, Palacios IF. Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation. Br Heart J 1988;60:299-308. 7. Chan K, Sochowski R. Comparison of transesophageal continuous wave Doppler with transthoracic Doppler in the assessment of mitral stenosis [Abstract]. J Am Coli Cardiol 1992;19:201A. 8. Thomas JD, Wilkins GT, Choong CYP, et al. Inaccuracy of mitral pressure half-time immediately after percutaneous mitral valvotomy. Circulation 1988;78:980-93. 9. Chen C, Wang Y, Guo B, Lin Y. Reliability of the Doppler pressure half-time method for assessing effects of percutaneous mitral balloon valvuloplasty. J Am Coli Cardiol 1989;13:1309-13. 10. Tabbalat RA, Haft JI. Effect of severe pulmonary hypertension on the calculation of mitral valve area in patients with mitral stenosis. Am Heart J 1991;121:488-93. 11. Martin RP, Rakowski H, Kleiman JH, Beaver W, London E, Popp RL. Reliabiliry and reproducibility of two-dimensional echocardiographic measurement of the stenotic mitral valve orifice area. Am J Cardiol 1979;43:560-8. 12. Davison MB, Cohen GI, Marwick TH, et al. The frequency of acquisition and quality of images obtained by transesophageal echocardiography. A prospective study of 100 consecutive cases [Abstract]. J AM Soc ECHOCARDIOGR 1991;4:288.
We describe the utility of transesophageal echocardiography in a patient undergoing emergent closed mitral commissurotomy. Two-dimensional images provided an assessment of valve morphology and mobility while Doppler echocardiography was used to monitor the occurrence of mitral regurgitation and changes in valve gradient and area. (J AM Soc ECHOCARDIOGR 1993;6:332-4.)
T
ransesophageal echocardiography is useful to monitor and guide percutaneous balloon mitral valvuloplasty. It allows assessment of mitral valve morphology and detection of left atrial clot and mitral regurgitation. 1•2 Although percutaneous balloon mitral valvuloplasty and open mitral valve reconstruction have largely supplanted closed mitral commissurotomy, this older technique is still performed to alleviate mitral stenosis when cardiopulmonary bypass is not readily available. 3 This article describes the application of transesophageal echocardiography during closed commissurotomy in a patient who was in shock and had severe pulmonary hypertension.
CASE REPORT
A 44-year-old woman with known mitral stenosis was admitted to a local hospital with fever, cough, and increasing dyspnea. During the next 48 hours, her condition worsened in spite of antibiotic treatment for suspected pneumonia. Respiratory failure and hypotension ensued and she was transferred emergendy to the Cleveland Clinic while receiving dopamine, dobutamine, and norepinephrine bitartrate (Levophed). On arrival, she was comatose and anuric with a heart rate of 116 beats I min and a systolic blood pressure of 50 mm Hg. Diffuse rales in both lung fields obscured heart sounds. Her extremities were cool and without edema. A chest x-ray film showed diffuse pulmonary infiltrates. Hypotension was treated with placement of an intraaortic balloon
From the Department of Cardiology and Cardiothoracic Surgery of The Cleveland Clinic Foundation. Reprint requests: Gerald 1. Cohen, MD, The Cleveland Clinic Foundation, Department of Cardiology F-15, 9500 Euclid Ave., Cleveland, OH 44195. Copyright © 1993 by the American Society of Echocardiography. 0894-7317/93 $1.00 +.10 27/1/44118
332
pump and increased Levophed infusion. A transesophageal echocardiogram (Hewlett Packard Sonos 1000, Andover, Mass.) revealed severe mitral stenosis without regurgitation, mean gradient of 18 mm Hg, and a valve area of 0.5 cm2 (pressure half-time = 418 msec) (Figure 1, A). Spontaneous contrast without thrombus was present in the severely dilated left atrium. Although the left ventricle was small and hyperdynamic, the right ventricle showed severe dilatation and dysfunction. No tricuspid regurgitation was present; however, Swan-Ganz catheter (Baxter Healthcare Corp., Santa Ana, Calif.) measurements revealed a pulmonary artery pressure of 102/48 mmHg. Percutaneous balloon mitral valvuloplasty was deferred because of concern that the high right-sided pressures might cause significant right-to-left shunting through a punctured interatrial septum with resulting hypoxemia. 4 In face of her severe hemodynamic instability, she was rushed to the operating room and a closed mitral commissurotomy was performed. A Tubbs dilator was placed into the left ventricle through an apical incision and was guided between the mitral leaflets by the surgeon's finger in the left atrium via an appendage incision (Figure 1, B). The valve area was assessed by surgical palpation and continuous wave Doppler after each of two dilatations of the mitral orifice (Figure 1, C). With the second dilatation, the mean Doppler gradient fell to 6 mm Hg and valve area increased to 3.0 cm2 (pressure half-time = 73 msec) (Figure 1, D). Transesophageal imaging showed improved leaflet mobility without mitral regurgitation and significandy improved right ventricular function. Cardiac index increased from 1 LI mini m 2 before surgery to 3 L/min/m2 after. However, pulmonary artery pressure remained high and did not fall until several days later. The postoperative course was complicated by severe encephalopathy, renal failure, bacteremia; respiratory distress syndrome, and thrombocytopenia.
Journal of the American Society of Echocardiography Volume 6 Number 3 Part 1
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Figure 1. Transverse four-chamber transesophageal views. A, Severe mitral stenosis before commissurotomy with small left ventricle (LV) and enlarged right ventricle (R V). Significant subvalvular thickening and stenosis, with relatively mild calcification, was present. B, Tubbs dilator (arrows) has passed between leaflets and is visible in the left atrium. C, After commissurotomy, the valve and subvalvular apparatus appear less stenosed. D, Intraoperative comparison of continuous wave Doppler profile of transmitral velocity before (above) and after (below) commissurotomy where a reduced gradient and shorter pressure half-time are apparent. Arrow indicates scale marker of 2 m/sec. RA, Right atrium; LA, left atrium.
Two weeks after surgery, a transthoracic echocardiogram demonstrated mild mitral stenosis with a valve area of 1. 7 cm2 and a mean gradient of 6 mm Hg (pressure half-time = 126 msec). The patient left the intensive care unit on the sixtieth postoperative day and was discharged home 2 weeks later neurologically intact. Since her discharge, she has had an uneventful clinical course and has resumed her normal activities.
DISCUSSION
The reported case posed an urgent and extraordinary management dilemma. In face of severe pulmonary hypertension and systemic hypotension, immediate
relief of severe mitral stenosis was essential. Utilization of cardiopulmonary bypass in this situation would have rapidly stabilized her hemodynamic status and allowed for a more refined open commissurotomy. However, patients with severe pulmonary hypertension who undergo mitral surgery may not be weanable from cardiopulmonary bypass after surgery because of bypass-associated worsening of right ventricular function and pulmonary hypertension. 5 We believed that our patient was at high risk of this complication because of severe right ventricular dysfunction, sepsis, and pneumonia. Closed mitral commissurotomy offered an expeditious and definitive (though unorthodox) solution to a dire situation. Transesophageal echocardiography was extremely useful in this patient's management. Before surgery,
Journal of the American Society of Echocardiography May-June 1993
334 Cohen et at.
knowledge of the mitral valve's morphologic condition (valve mobility and valvular and subvalvular calcification)6 and lack of regurgitation indicated that a closed mitral comissurotomy would be feasible. During surgery, transesophageal imaging allowed the surgeon to proceed aggressively with the knowledge that dilatation of the valve was not causing valvular regurgitation. The option of transesophageal continuous wave Doppler was particularly useful as it permitted preoperative and intraoperative measurement of the valve gradient and area allowing confirmation that the valvotomy was adequate despite the fact that the pulmonary artery pressure remained very elevated. It was observed that the pressure half-time increased significantly between the immediate and 2week postoperative assessment, suggesting reduction in valve area. Chan and Suchowske have shown that transesophageal measurement of mitral pressure halftime correlates well with transthoracic observations. It has been shown,8 however, that the sudden changes in atrioventricular compliance and transmitral pressure gradient that accompany acute valvotomy render the pressure half-time method unreliable in this setting. This may explain in part the discrepancy in mitral valve area observed immediately after commissurotomy and 2 weeks later. Although mitral pressure half-time is considered a pure inverse measure of mitral valve area, it additionally varies directly with the net compliance of the atrium and ventricle and with the square root of the transmitral pressure gradient. 8 In the current case, the pressure gradient fell threefold and atrial compliance likely increased as it was decompressed, whereas ventricular compliance likely fell with the sudden volume loading of the chronically underfilled ventricle. It is thus not surprising that the mitral pressure half-time seemed to be shortened initially out of proportion to the acute increase in valve area. Of note, Chen et al. 9 demonstrated in 18 patients that the pressure halftime method overestimates mitral valve area immediately after valvuloplasty but regains accuracy within 48 hours; the increase in pressure half-time in our case at 2 weeks appears consistent with this observation, although actual recoil of the mitral orifice may have also played a role. In contrast, the fall in pulmonary arterial pressure is not a likely cause of this change because pulmonary hypertension has been shown not to affect Doppler measurements of pressure half-time. 10 An attractive alternative to the pressure half-time assessment of mitral valve area is direct planimetry of the orifice from a short-axis image of the valve. 11 Unfortunately, in the current case, both biplane
transesophageal echocardiographic views were oblique to the orifice. In fact, we have found that a perfect short-axis view of the mitral valve is obtainable in only about 40% of patients during singleplane transesophageal echocardiography.12 Epicardial and multiplane transesophageal echocardiography should be superior alternatives for planimetry of the mitral valve orifice. In spite of these limitations, however, transesophageal echocardiography facilitated the emergent care of our patient and was particularly useful in determining that an adequate commissurotomy had been accomplished. We thank Jody Karabinus for secretarial assistance. REFERENCES 1. Jaarsma W, Visser CA, Suttorp MI, Haagen FDH, Ernst SMPG. Transesophageal echocardiography during percutaneous balloon mitral valvuloplasty. J AM Soc ECHOCARDIOGR 1990;3:384-91. 2. Lock JE, Khalilullah M, Shrivastava S, Bahl V, Keane JF. Percutaneous catheter commissurotomy in rheumatic mitral stenosis. N Engl J Med 1985;313:1515-8. 3. Cohn LH, Allred EN, Cohn LA, Disesa VI, Shemin RJ, Collins JJ. Long-term results of open mitral valve reconstruction for mitral stenosis. Am J CardioI1985;55:731-4. 4. Goldberg N, Roman CF, Cha SD, et al. Right to left interatrial shunting following balloon mitral valvuloplasty. Cathet Cardiovasc Diagn 1989;16:133-5. 5. D'Ambra MN, LaRaia PI, Philbin DM, Watkins WD, Hilgenberg AD, Buckley MJ. Prostaglandin El, a new therapy for refractory right heart failure and pulmonary hypertension after mitral valve replacement. J Thorac Cardiovasc Surg 1985;89:567-72. 6. Wilkins GT, Weyman AE, Abascal VM, Block PC, Palacios IF. Percutaneous balloon dilatation of the mitral valve: an analysis of echocardiographic variables related to outcome and the mechanism of dilatation. Br Heart J 1988;60:299-308. 7. Chan K, Sochowski R. Comparison of transesophageal continuous wave Doppler with transthoracic Doppler in the assessment of mitral stenosis [Abstract]. J Am Coli Cardiol 1992;19:201A. 8. Thomas JD, Wilkins GT, Choong CYP, et al. Inaccuracy of mitral pressure half-time immediately after percutaneous mitral valvotomy. Circulation 1988;78:980-93. 9. Chen C, Wang Y, Guo B, Lin Y. Reliability of the Doppler pressure half-time method for assessing effects of percutaneous mitral balloon valvuloplasty. J Am Coli Cardiol 1989;13:1309-13. 10. Tabbalat RA, Haft JI. Effect of severe pulmonary hypertension on the calculation of mitral valve area in patients with mitral stenosis. Am Heart J 1991;121:488-93. 11. Martin RP, Rakowski H, Kleiman JH, Beaver W, London E, Popp RL. Reliabiliry and reproducibility of two-dimensional echocardiographic measurement of the stenotic mitral valve orifice area. Am J Cardiol 1979;43:560-8. 12. Davison MB, Cohen GI, Marwick TH, et al. The frequency of acquisition and quality of images obtained by transesophageal echocardiography. A prospective study of 100 consecutive cases [Abstract]. J AM Soc ECHOCARDIOGR 1991;4:288.