Ann Thorac Surg 2004;78:e79-e80
© 2004 The Society of Thoracic Surgeons
Case report
Unrecognized Left Ventricular Thrombus During Reoperative Coronary Artery Bypass Grafting
Sanjay Sharma, MDa,
Afshin Ehsan, MDa,
Gregory S. Couper, MDa,
Stanton K. Shernan, MDb,
Richard M. Wholey, MDc,
Sary F. Aranki, MDa,*
a Division of Cardiac Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
b Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
c Department of Medicine, University of Massachusetts Memorial Hospital, Worcester, Massachusetts, USA
Accepted for publication October 16, 2003.
* Address reprint requests to Dr Aranki, Division of Cardiac Surgery, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115, USA
saranki{at}partners.org
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Abstract
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Left ventricular thrombus after myocardial infarction is relatively common but rarely threatening enough to warrant surgical removal at the time of coronary revascularization. The rare cases of ventricular thrombectomy described in the literature involve a pedunculated thrombus. We describe an urgent coronary revascularization procedure in a patient who had unrecognized left ventricular thrombus. The large clot was detected by transesophageal echocardiography after decannulation in a hemodynamically unstable patient. The thrombus was removed after placing the patient back on cardiopulmonary bypass emergently. He recovered and was discharged with no neurologic sequelae. Aggressive removal of clot using cardiopulmonary bypass is warranted even for the critically ill patient.
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Introduction
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Left ventricular thrombus is rarely encountered in routine cardiac surgical practice. It is mainly seen in association with left ventricular aneurysms, myocardial infarction, or cardiomyopathy and is of the laminated, striated platelet-rich type. This thrombus is often adherent to the ventricular wall, and is of low risk for embolization [1]. We describe an unstable patient who had unrecognized fresh left ventricular mural thrombus that became dislodged during manipulation for coronary exposure. We were faced with a difficult decision to recannulate a hemodynamically unstable patient and remove the clot on cardiopulmonary bypass.
A 78-year-old man was admitted with postinfarction angina on April 24, 2003, after 3 days of chest pain. He had a previous myocardial infarction and coronary artery bypass grafting in 1994 with saphenous vein grafts to the left anterior descending artery (LAD), first obtuse marginal branch (OM1) and second obtuse marginal branch (OM2), and the posterior descending artery (PDA). A dual-chamber pacemaker had been placed previously for sick sinus syndrome. Cardiac enzymes were positive for infarction and electrocardiogram showed nonspecific T-wave anomalies and a paced rhythm.
Coronary angiography revealed a 30% left main artery lesion, a 100% proximal LAD lesion, a 90% proximal circumflex lesion, and a 100% proximal right coronary artery lesion in the native circulation. The vein graft to the LAD was occluded. The sequential vein graft to the first and second marginal branches and the vein graft to the posterior descending artery were heavily diseased but patent. Ventriculography and transthoracic echocardiography (TTE) revealed severe global hypokinesis with distal apical dyskinesis with no thrombus and an ejection fraction of 20%. Creatinine was elevated to 2.4, and the remainder of the laboratory data was within normal limits. Although targets were small, the patient was accepted for surgery because of ongoing angina refractory to medical treatment.
Transesophageal echocardiography (TEE) is used routinely, and confirmed preoperative findings (Fig 1). The right femoral vessels were cannulated, and redo sternotomy was performed. The left internal mammary artery (LIMA) and left long saphenous vein were harvested. During the pericardial dissection near the posterior descending artery graft, inferior ST-segment elevation was noted and cardiopulmonary bypass was instituted. Antegrade and retrograde cardioplegia was delivered after cross clamping the aorta. Aprotinin was administered during bypass according to our center's usual protocol for reoperative procedures. A sequential vein graft was constructed to the OM1, OM2, and PDA. The LAD was heavily diseased, and an endarterectomy was performed with the vessel opened in its entire length. After flushing debris with retrograde cardioplegia, the vessel was reconstructed distally with a saphenous vein patch and the LIMA was anastomosed to the remaining proximal defect.
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Fig 1. Transesophageal echocardiographic, midesophageal two-chamber view before the initiation of cardiopulmonary bypass. Definitive echocardiographic evidence of the left ventricular (LV) apical thrombus is not obvious. (LA = left atrium.)
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The patient was weaned with intraaortic balloon pump (IABP) counterpulsation and inotropic support. After decannulation, TEE revealed a mobile lacunar left ventricular cavity mass near the apex (Fig 2). This mass was also confirmed on epicardial echocardiography. We believed it represented a threatening left ventricular thrombus. The patient was cannulated centrally, and cardiopulmonary bypass was reinstituted. A large, old, organized, laminated thrombus with fresh platelet deposits (Fig 3) was extracted through a ventriculotomy in the dyskinetic segment of the anterior wall near the apex of the left ventricle. The anterior wall was largely scarred, and therefore a formal endoventricular repair was undertaken. The patient was weaned successfully from cardiopulmonary bypass with inotropic support and IABP.
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Fig 2. Transesophageal echocardiography revealing the left ventricular lacunar thrombus. (LA = left atrium; LV = left ventricle; RV = right ventricle.)
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Fig 3. Operative photograph showing the left ventricular thrombus with obvious endocardial impressions on the clot.
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The postoperative course was uneventful. Inotropic agents and IABP were weaned on day 1. Postoperative TTE showed an ejection fraction of 30% with anterior akinesis and no thrombus. The patient was discharged on day 8 with no neurologic deficit or perioperative infarct.
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Comment
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Postinfarction endoventricular thrombosis is more common in anterior infarcts with a poor ejection fraction. Thrombus is generally smooth, conforming to the ventricular wall. Hartman and colleagues [2] have suggested thrombectomy should be reserved for the protruding pedunculated variant, which is rare. This case suggests that the smooth variant can be dislodged during ventricular manipulation. If not appreciated, this can lead to systemic embolization.
Potentially, a ventriculotomy as the route of thombectomy may lead to decrease in ejection fraction [3], ventricular arrhythmia, and aneurysm formation [4]. In our unstable patient we wanted to avoid cross clamping and cardioplegia. The ventriculotomy was made through scar tissue, and a subsequent Dor endoventricular repair was then performed. Postoperative echocardiography showed an improvement in ejection fraction by 10% despite the ventriculotomy.
Alternative techniques for extraction of left ventricular thrombus have been described. These include transaortic extraction using a thoroscope [5], passing a mediastinoscope through the mitral valve for complete extraction [6], and the use of plasminogen activator to successfully lyse clot without evidence of embolization [7]. We did not think any of these alternatives were appropriate, as this patient was extremely unstable.
Detection of smooth thrombus using TTE and TEE maybe difficult. If the thrombus is thin and adherant, diagnostic criteria such as localizing thrombus with a clear thrombus-blood interface in at least two planes adjacent to dyskinetic myocardium may not be accurate. In patients undergoing coronary revascularization with recent preoperative infarcts, the surgeon needs to be consider thrombus dislodgement during the procedure. Intraoperative TEE evaluation before decannulation to exclude dislodgement is prudent. Direct inspection with a thoroscope may be considered if a concomitant aortic or mitral procedure is being performed.
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Acknowledgments
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We thank Heather Couture for preparing the manuscript and Luigino Nascimben, MD, for the intraoperative photographs.
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References
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Abstract
Introduction
