Case Anecdotes, Comments and Opinions Continuous flow left ventricular assist device related aortic root thrombosis complicated by left main coronary artery occlusion Sachin Shah, MD, Mandeep R. Mehra, MD, Gregory S. Couper, MD, and Akshay S. Desai, MD From the Brigham and Women’s Hospital Heart and Vascular Center and Harvard Medical School, Boston, MA
Figure 1 Contrast injection in the aortic root revealing thrombus in the left coronary cusp partially obstructing the left main coronary artery.
119 Thrombosis and thromboembolism are an increasingly recognized source of early postoperative morbidity following institution of mechanical circulatory support.1 We report an unusual case of aortic root thrombus occluding the left main coronary artery four days after implantation of an axial continuous flow HeartMate II (Thoratec, Pleasonton, CA USA) left ventricular assist device (LVAD). A 48-year old man with refractory, inotrope-dependent heart failure due to idiopathic dilated cardiomyopathy underwent elective LVAD implantation as a bridge to cardiac transplantation. Aspirin 325mg was initiated within 24 hours of surgery and unfractionated intravenous heparin (target partial thromboplastin time 60-80 seconds) was started within 36 hours. Lactate dehydrogenase was measured at 502 U/L. On the fourth postoperative day, an echocardiogram was performed for LVAD speed and flow optimization. The pump speed was decreased from 9600 RPM to 8600 RPM until intermittent aortic valve opening was achieved; immediately after the pump speed was reduced, the patient had abrupt onset of nausea, dyspnea and left shoulder discomfort. An electrocardiogram revealed 4mm ST-segment elevations in leads V2-V6 consistent with anterior myocardial injury. The patient underwent emergent coronary angiography, which revealed thrombotic obstruction of the terminal portion of the left anterior descending (LAD) coronary artery, but no proximal disease. Root aortography revealed a thrombus in the left coronary cusp obstructing the left main coronary artery ostium (Figure 1). Transesophageal echocardiography confirmed the presence of a thrombus in the left coronary cusp with dense spontaneous echo contrast noted throughout the aortic root (Figure 2). A guide catheter was left engaged in the left main coronary artery to protect against recurrent
Figure 2 Transesophageal echocardiogram, short axis of the aortic valve revealing thrombus in the left coronary cusp, spontaneous echo contrast was noted in the remaining aortic valve cusps.
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coronary occlusion by the thrombus and the patient was transferred emergently to the operating room. He underwent a successful aortic root exploration and thrombectomy and a saphenous vein graft was used to bypass the LAD. Postoperative transesophageal echocardiography revealed resolution of the thrombus but persistent spontaneous echo contrast in the aortic root. The patient has been managed with Coumadin (Bristol-Myers Squibb, Princeton, NJ) to target an intensified anticoagulation target (goal international normalized ratio of 2.5 to 3.5). A workup for inherited and acquired causes of thrombophilia is in progress. Aortic root thrombosis in patients with a HeartMate II LVAD has been reported previously in the literature.2,3 Flow in the aortic root in patients with continuous flow LVADs has experimentally been shown to be relatively stagnant, especially when the aortic valve does not open,4 and such stasis may be an important risk factor for thrombosis. While the optimal strategy for prevention of this complication is not defined, careful attention to anticoagulant and antiplatelet therapy in the post-operative period, as well as adjustment of pump speed to permit intermittent aortic valve opening and flow through the aortic root may be important considerations. For
those who develop thrombus within the aortic root but remain asymptomatic, intensification of anticoagulant and antiplatelet therapy alone may be adequate; in this case, however, acute myocardial infarction and persistent left main obstruction obligated immediate surgical intervention.
Disclosure statement Dr. Mehra discloses consulting for Thoratec. The others report no conflicts.
References 1. Mehra MR, Stewart GC, Uber PA. The vexing problem of thrombosis in long-term mechanical circulatory support. J Heart Lung Transplant 2014;33:1-11. 2. Freed BH, Jeevanandam V, Jolly N. Aortic root and valve thrombosis after implantation of a left ventricular assist device. J Invasive Cardiol 2011;23:E63-5. 3. Demirozu ZT, Frazier OH. Aortic valve noncoronary cusp thrombosis after implantation of a nonpulsatile, continuous-flow pump. Tex Heart Inst J 2012;39(5):618-20. 4. Kar B, Delgado RM, Frazier OH, et al. The effect of LVAD aortic outflow-graft placement on hemodynamics and flow. Implantation technique and computer flow modeling. Tex Heart Inst J 2005;32:294-8.
Figure 1 Contrast injection in the aortic root revealing thrombus in the left coronary cusp partially obstructing the left main coronary artery.
119 Thrombosis and thromboembolism are an increasingly recognized source of early postoperative morbidity following institution of mechanical circulatory support.1 We report an unusual case of aortic root thrombus occluding the left main coronary artery four days after implantation of an axial continuous flow HeartMate II (Thoratec, Pleasonton, CA USA) left ventricular assist device (LVAD). A 48-year old man with refractory, inotrope-dependent heart failure due to idiopathic dilated cardiomyopathy underwent elective LVAD implantation as a bridge to cardiac transplantation. Aspirin 325mg was initiated within 24 hours of surgery and unfractionated intravenous heparin (target partial thromboplastin time 60-80 seconds) was started within 36 hours. Lactate dehydrogenase was measured at 502 U/L. On the fourth postoperative day, an echocardiogram was performed for LVAD speed and flow optimization. The pump speed was decreased from 9600 RPM to 8600 RPM until intermittent aortic valve opening was achieved; immediately after the pump speed was reduced, the patient had abrupt onset of nausea, dyspnea and left shoulder discomfort. An electrocardiogram revealed 4mm ST-segment elevations in leads V2-V6 consistent with anterior myocardial injury. The patient underwent emergent coronary angiography, which revealed thrombotic obstruction of the terminal portion of the left anterior descending (LAD) coronary artery, but no proximal disease. Root aortography revealed a thrombus in the left coronary cusp obstructing the left main coronary artery ostium (Figure 1). Transesophageal echocardiography confirmed the presence of a thrombus in the left coronary cusp with dense spontaneous echo contrast noted throughout the aortic root (Figure 2). A guide catheter was left engaged in the left main coronary artery to protect against recurrent
Figure 2 Transesophageal echocardiogram, short axis of the aortic valve revealing thrombus in the left coronary cusp, spontaneous echo contrast was noted in the remaining aortic valve cusps.
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The Journal of Heart and Lung Transplantation, Vol 33, No 1, January 2014
coronary occlusion by the thrombus and the patient was transferred emergently to the operating room. He underwent a successful aortic root exploration and thrombectomy and a saphenous vein graft was used to bypass the LAD. Postoperative transesophageal echocardiography revealed resolution of the thrombus but persistent spontaneous echo contrast in the aortic root. The patient has been managed with Coumadin (Bristol-Myers Squibb, Princeton, NJ) to target an intensified anticoagulation target (goal international normalized ratio of 2.5 to 3.5). A workup for inherited and acquired causes of thrombophilia is in progress. Aortic root thrombosis in patients with a HeartMate II LVAD has been reported previously in the literature.2,3 Flow in the aortic root in patients with continuous flow LVADs has experimentally been shown to be relatively stagnant, especially when the aortic valve does not open,4 and such stasis may be an important risk factor for thrombosis. While the optimal strategy for prevention of this complication is not defined, careful attention to anticoagulant and antiplatelet therapy in the post-operative period, as well as adjustment of pump speed to permit intermittent aortic valve opening and flow through the aortic root may be important considerations. For
those who develop thrombus within the aortic root but remain asymptomatic, intensification of anticoagulant and antiplatelet therapy alone may be adequate; in this case, however, acute myocardial infarction and persistent left main obstruction obligated immediate surgical intervention.
Disclosure statement Dr. Mehra discloses consulting for Thoratec. The others report no conflicts.
References 1. Mehra MR, Stewart GC, Uber PA. The vexing problem of thrombosis in long-term mechanical circulatory support. J Heart Lung Transplant 2014;33:1-11. 2. Freed BH, Jeevanandam V, Jolly N. Aortic root and valve thrombosis after implantation of a left ventricular assist device. J Invasive Cardiol 2011;23:E63-5. 3. Demirozu ZT, Frazier OH. Aortic valve noncoronary cusp thrombosis after implantation of a nonpulsatile, continuous-flow pump. Tex Heart Inst J 2012;39(5):618-20. 4. Kar B, Delgado RM, Frazier OH, et al. The effect of LVAD aortic outflow-graft placement on hemodynamics and flow. Implantation technique and computer flow modeling. Tex Heart Inst J 2005;32:294-8.
