Ischemic Mitral Regurgitation during Temporary Coronary-Artery Ligation
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《新英格兰医药杂志》
To the Editor: Ischemic mitral regurgitation is defined as mitral insufficiency that occurs as a result of coronary artery disease in the absence of intrinsic structural abnormalities of the mitral valve. Ischemic mitral regurgitation develops in approximately 19 percent of patients with myocardial infarction1 and tends to be associated with an increase in the severity of coronary artery disease and an increased mortality. Despite extensive laboratory and clinical investigation, the mechanism of ischemic mitral regurgitation has yet to be fully elucidated and remains the subject of considerable debate. We report the development of acute severe mitral regurgitation during temporary ligation of the left anterior descending coronary artery in a patient undergoing off-pump coronary-artery bypass grafting. Release of the ligation of the left anterior descending coronary artery was associated with the immediate cessation of ischemic mitral regurgitation.
A 43-year-old man presented with chest pain. Cardiac catheterization was performed, which showed an isolated stenosis of the left anterior descending coronary artery. Coronary revascularization was recommended with a graft of the left internal thoracic artery to the left anterior descending coronary artery by means of off-pump coronary-artery bypass, thereby avoiding the use of cardiopulmonary bypass. After induction of general anesthesia, sternotomy, preparation of the left internal thoracic artery, and positioning of the heart, transesophageal echocardiography showed only trace mitral regurgitation and a normal pulmonary venous Doppler flow-velocity profile (Figure 1A). Immediately after the temporary ligation of the left anterior descending coronary artery as required during off-pump coronary-artery bypass, transesophageal echocardiography with Doppler flow showed a wide-based mitral regurgitation jet, extending throughout the left atrium; the development of pulmonary venous systolic flow reversal suggested severe mitral regurgitation (Figure 1B). Despite the presence of ischemic mitral regurgitation, the patient's hemodynamic status remained stable, permitting the completion of the anastomosis between the left internal thoracic artery and the left anterior descending coronary artery on the beating heart. Immediately after the release of the temporary ligation of the left anterior descending coronary artery, the degree of ischemic mitral regurgitation returned to baseline. The patient tolerated the operation well, recovered quickly, and was discharged home on the fourth postoperative day. Transthoracic echocardiography performed four weeks after the operation confirmed only trace residual mitral regurgitation.
Figure 1. Transesophageal Echocardiographic Imaging (Midesophageal Four-Chamber View) of the Mitral Valve after Sternotomy and Exposure, and Positioning of the Heart in a Patient Undergoing Off-Pump Coronary-Artery Bypass Grafting.
Panel A shows Doppler color-flow mapping of a small mitral-regurgitation jet (orange and yellow) (top), a finding consistent with trace mitral regurgitation. The Doppler flow-velocity profile of the left upper pulmonary vein shows normal systolic forward flow into the left atrium (bottom). Panel B shows a wide-based mitral-regurgitation jet and systolic reversal of pulmonary venous flow, indicating severe mitral regurgitation, which developed after temporary ligation of the left anterior descending coronary artery. (A video clip of the transesophageal echocardiographic imaging is available with the full text of this letter at www.nejm.org.)
Possible mechanisms by which acute ischemia can cause mitral regurgitation include asymmetric annular dilatation, an alteration in papillary-muscle contraction, leaflet tethering, regional or global left ventricular dysfunction, and distortion of the left ventricular geometry.2,3,4 Although mitral regurgitation can develop during off-pump coronary-artery bypass owing to mechanical factors that are associated with mobilization and stabilization of the heart to facilitate the exposure of the coronary artery,5 the time course and the complete reversibility associated with the temporary ligation and release of the left anterior descending coronary artery strongly support an ischemic cause of mitral regurgitation in this patient.
Holger K. Eltzschig, M.D.
University Clinic for Anesthesiology and Intensive Care Medicine
D-72076 Tübingen, Germany
heltzschig@partners.org
Stanton K. Shernan, M.D.
Peter Rosenberger, M.D.
Harvard Medical School
Boston, MA 02115
References
Grigioni F, Enriquez-Sarano M, Zehr KJ, Bailey TR, Tajik AJ. Ischemic mitral regurgitation: long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 2001;103:1759-1764.
Kono T, Sabbah HN, Rosman H, et al. Mechanism of functional mitral regurgitation during acute myocardial ischemia. J Am Coll Cardiol 1992;19:1101-1105.
Otsuji Y, Handschumacher MD, Liel-Cohen N, et al. Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation. J Am Coll Cardiol 2001;37:641-648.
He S, Fontaine AA, Schwammenthal E, Yoganathan AP, Levine RA. Integrated mechanism for functional mitral regurgitation: leaflet restriction versus coapting force: in vitro studies. Circulation 1997;96:1826-1834.
George SJ, Al-Ruzzeh S, Amrani M. Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance -- a three-dimensional echocardiography reconstruction study. Ann Thorac Surg 2002;73:1424-1430.
A 43-year-old man presented with chest pain. Cardiac catheterization was performed, which showed an isolated stenosis of the left anterior descending coronary artery. Coronary revascularization was recommended with a graft of the left internal thoracic artery to the left anterior descending coronary artery by means of off-pump coronary-artery bypass, thereby avoiding the use of cardiopulmonary bypass. After induction of general anesthesia, sternotomy, preparation of the left internal thoracic artery, and positioning of the heart, transesophageal echocardiography showed only trace mitral regurgitation and a normal pulmonary venous Doppler flow-velocity profile (Figure 1A). Immediately after the temporary ligation of the left anterior descending coronary artery as required during off-pump coronary-artery bypass, transesophageal echocardiography with Doppler flow showed a wide-based mitral regurgitation jet, extending throughout the left atrium; the development of pulmonary venous systolic flow reversal suggested severe mitral regurgitation (Figure 1B). Despite the presence of ischemic mitral regurgitation, the patient's hemodynamic status remained stable, permitting the completion of the anastomosis between the left internal thoracic artery and the left anterior descending coronary artery on the beating heart. Immediately after the release of the temporary ligation of the left anterior descending coronary artery, the degree of ischemic mitral regurgitation returned to baseline. The patient tolerated the operation well, recovered quickly, and was discharged home on the fourth postoperative day. Transthoracic echocardiography performed four weeks after the operation confirmed only trace residual mitral regurgitation.
Figure 1. Transesophageal Echocardiographic Imaging (Midesophageal Four-Chamber View) of the Mitral Valve after Sternotomy and Exposure, and Positioning of the Heart in a Patient Undergoing Off-Pump Coronary-Artery Bypass Grafting.
Panel A shows Doppler color-flow mapping of a small mitral-regurgitation jet (orange and yellow) (top), a finding consistent with trace mitral regurgitation. The Doppler flow-velocity profile of the left upper pulmonary vein shows normal systolic forward flow into the left atrium (bottom). Panel B shows a wide-based mitral-regurgitation jet and systolic reversal of pulmonary venous flow, indicating severe mitral regurgitation, which developed after temporary ligation of the left anterior descending coronary artery. (A video clip of the transesophageal echocardiographic imaging is available with the full text of this letter at www.nejm.org.)
Possible mechanisms by which acute ischemia can cause mitral regurgitation include asymmetric annular dilatation, an alteration in papillary-muscle contraction, leaflet tethering, regional or global left ventricular dysfunction, and distortion of the left ventricular geometry.2,3,4 Although mitral regurgitation can develop during off-pump coronary-artery bypass owing to mechanical factors that are associated with mobilization and stabilization of the heart to facilitate the exposure of the coronary artery,5 the time course and the complete reversibility associated with the temporary ligation and release of the left anterior descending coronary artery strongly support an ischemic cause of mitral regurgitation in this patient.
Holger K. Eltzschig, M.D.
University Clinic for Anesthesiology and Intensive Care Medicine
D-72076 Tübingen, Germany
heltzschig@partners.org
Stanton K. Shernan, M.D.
Peter Rosenberger, M.D.
Harvard Medical School
Boston, MA 02115
References
Grigioni F, Enriquez-Sarano M, Zehr KJ, Bailey TR, Tajik AJ. Ischemic mitral regurgitation: long-term outcome and prognostic implications with quantitative Doppler assessment. Circulation 2001;103:1759-1764.
Kono T, Sabbah HN, Rosman H, et al. Mechanism of functional mitral regurgitation during acute myocardial ischemia. J Am Coll Cardiol 1992;19:1101-1105.
Otsuji Y, Handschumacher MD, Liel-Cohen N, et al. Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation. J Am Coll Cardiol 2001;37:641-648.
He S, Fontaine AA, Schwammenthal E, Yoganathan AP, Levine RA. Integrated mechanism for functional mitral regurgitation: leaflet restriction versus coapting force: in vitro studies. Circulation 1997;96:1826-1834.
George SJ, Al-Ruzzeh S, Amrani M. Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance -- a three-dimensional echocardiography reconstruction study. Ann Thorac Surg 2002;73:1424-1430.