Circulation. 2008;118:e73-e75
doi: 10.1161/CIRCULATIONAHA.107.759498
(Circulation. 2008;118:e73-e75.)
© 2008 American Heart Association, Inc.
Images in Cardiovascular Medicine |
Acute Reversible Bioprosthetic Mitral Valve Stenosis Caused by Heparin-Induced Thrombocytopenia
Amnon Y. Zlotnick, MD;
Jeryes Shehadeh, MD;
Moshe Y. Flugelman, MD;
Sylvie A. Bursztein-De Myttenaere, MD;
Tamar Gaspar, MD;
Avinoam Shiran, MD
From the Department of Cardiothoracic Surgery (A.Y.Z.), Department of Cardiovascular Medicine (J.S., M.Y.F. and A.S.), Department of Anesthesiology and Intensive Care (S.A.B.-D.M.) and Department of Radiology (T.G.), Lady Davis Carmel Medical Center and the Ruth and Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel.
Correspondence to Avinoam Shiran, MD, Director, Echocardiography, Department of Cardiovascular Medicine, Lady Davis Carmel Medical Center, 7 Michal St, Haifa 34362, Israel. E-mail shiranad{at}012.net.il
A 60-year-old woman with a 17-year-old prosthetic tilting disc mitral valve (MV) and chronic atrial fibrillation underwent emergency redo MV replacement for a stuck valve with a bioprosthetic valve (Medtronic Mosaic 27). Transesophageal echocardiography (TEE) on the fourth postoperative day showed a normal bioprosthetic valve. On the sixth postoperative day while the patient was still on intravenous heparin, her platelet count dropped to 63 000/µL and a heparin-induced thrombocytopenia (HIT) antibody assay was positive. Heparin was stopped, and the patient was treated with intravenous danaparoid sodium, a factor Xa inhibitor. Oral warfarin was started when thrombocytopenia resolved. The patient was in respiratory failure and could not be weaned off the ventilator. Contrast-enhanced computed tomography on the 14th postoperative day was negative for pulmonary emboli. However, large thrombi lining the left atrial wall and thickened bioprosthetic MV leaflets were seen (Figure 1). A repeat TEE the next day showed severe mitral stenosis, due to diffuse thrombosis and immobilization of the bioprosthetic valve leaflets, and large thrombi adherent to the left atrial walls (Figure 2 and online-only Data Supplement Movie I).
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Figure 1. A 64-slice nongated computed tomography of the chest. A, Oblique transverse 4-chamber view showing a large thrombus adherent to the left atrial wall (arrows) and thickened bioprosthetic mitral valve leaflets (double arrows). B, Short-axis view at the level of the prosthetic mitral valve showing thickened leaflets (arrows). LA indicates left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; Ao, aorta; and PA, pulmonary artery.
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Figure 2. TEE performed on the 15th postoperative day. A, Midesophageal transverse view in diastole showing diffuse thrombosis of the bioprosthetic mitral valve leaflets (arrows) causing severe leaflet restriction and stenosis. Large immobile thrombi are adherent to the left atrial (LA) wall (double arrows). B, Transmitral continuous-wave Doppler showing severe mitral stenosis. Estimated mitral valve area using the pressure half time formula is 0.6 cm2, and the mean transvalvular gradient is 14 mm Hg. LV indicates left ventricle.
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Because the risk of surgical reintervention was deemed unacceptable, the patient was treated medically, and danaparoid sodium was stopped when adequate oral anticoagulation was achieved. A repeat TEE on the 25th postoperative day showed improved MV leaflet motion and less stenosis (online-only Data Supplement Movie II), and a TEE performed 10 weeks after the operation showed a normal bioprosthetic valve (Figure 3 and online-only Data Supplement Movie III).
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Figure 3. TEE performed 10 weeks postoperatively. A, Complete resolution of the bioprosthetic valve thrombus with normal leaflet appearance (arrows). B, A large thrombus is still adherent to the left atrial wall (arrow) but is partially detached (double arrow). C, Transmitral continuous-wave Doppler showing normal hemodynamics of the biopreosthetic valve. Estimated mitral valve area is 2.2 cm2, and the mean transvalvular gradient is 5 mm Hg.
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The patient was gradually weaned off ventilation. A transthoracic echocardiogram (TTE) performed 15 weeks after the operation showed a mobile left atrial thrombus partially obstructing the bioprosthetic valve in diastole (Figure 4 and online-only Data Supplement Movie IV). The patient suffered a minor stroke, and a repeat TTE 4 days later was normal (Figure 4 and online-only Data Supplement Movie V). The patient was finally discharged to rehabilitation.
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Figure 4. TTE using the apical 4-chamber view performed 15 weeks after surgery. A, Systolic frame showing a large left atrial (LA) thrombus (arrow). B, Diastolic frame showing prolapse of the LA thrombus (arrow) through the bioprosthetic mitral valve. C, Repeat TTE 4 days later showing absence of the LA thrombus in systole. D, Same view in diastole. LV indicates left ventricle.
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HIT is a disorder in which platelet activation and thrombosis is caused by antibodies against complexes of platelet factor 4 and heparin as a result of exposure to heparin.1 In this unique case, thrombosis was caused by the combination of platelet activation by HIT, the unendothelialized bioprosthetic material, and atrial fibrillation. Although left atrial thrombi in a patient with a bioprosthetic MV and HIT have been described,2 to our knowledge acute bioprosthetic valve stenosis caused by HIT has never been described before.
Management of this patient was complicated because severe mitral stenosis causes a vicious circle of further stasis and thrombosis in the left atrium causing more stenosis. Rapid lysis of the clot using fibrinolytic therapy might have caused a shower of emboli with devastating results. Slow lysis of the clot using danaparoid sodium and then long-term warfarin therapy enabled restoration of the bioprosthetic MV to normal, fortunately with relatively minor embolic sequelae. In such cases, the risk of another cardiac operation (in which heparin is contraindicated) should be weighed against the risk of systemic embolization.
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Disclosures
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None.
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Footnotes
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The online-only Data Supplement is available with this article at http://circ.ahajournals.org/cgi/content/full/118/4/e73/DC1.
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References
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1. Arepally GM, Ortel TL. Clinical practice: heparin-induced thrombocytopenia.
N Engl J Med. 2006; 355: 809–817.
[Free Full Text]2. Abraham BK, Chow CM, Latter DA, Mazer CD. Natural course of left atrial thrombi after bioprosthetic mitral valve replacement in a patient with heparin-induced thrombocytopenia. Can J Cardiol. 2005; 21: 1307–1308.[Medline]
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