Fracture Embolization of an Edwards-Duromedics Valve with Asymmetrical Closure

Introduction

The Edwards-Duromedics (ED) bileaflet prosthesis has been reported to yield good clinical results with low morbidity and functional improvement, nevertheless disc dislodgement and embolization have been reported to occur. ^{1 –5} The incidence of leaflet escapes was 0.029–0.08% per patient year and was higher in the mitral position than in the aortic position.

Case Report

In February 2005, a 46-year-old male presented at our hospital with severe breathlessness, which had started four hours prior to admission. In April 1988, the patient had undergone mitral valve replacement (ED bileaflet, 31mm) for residual regurgitation one month after mitral valvuloplasty in March at another hospital. A follow-up examination showed no complications and anticoagulation with warfarin (PT-INR: 2.0∼2.5) had been adequate until the patient underwent transthoracic echocardiography. It revealed mitral stenosis and the motion of one leaflet appeared fixed. Therefore, valve thrombosis was suspected and cinefluoroscopy was performed in August 2004. It showed that one leaflet was not moving smoothly and was not fully-open every fourth or fifth time. But it was not fixed (Figure 1a, 1b). Since he was asymptomatic, a large does of anticoagulants (tentative PT-INR: 3.0) was prescribed. The patient's clinical course was uneventful until this incidence.

OPEN IN VIEWER

Figure 1.

Cinefluoroscopy: (a, b) One leaflet of the Edwards-Duromedics valve not fully opened every fourth or fifth time (August 2004); (c) The leaflet previously showing irregular motion shows smooth movements, another leaflet has escaped (February 2005).

On admission, the patient appeared distressed and diaphoretic, with a blood pressure of 130/60 mm Hg and a pulse rate of 90 beats·min⁻¹. On auscultation, there was an audible mitral valve click and a grade 3/6 pansystolic murmur. Transthoracic echocardiography demonstrated good left ventricular function, severe torrential mitral regurgitation and pulmonary hypertension. However, the details of the leaflets could not be exactly determined. On cinefluoroscopy only the leaflet that had previously shown irregular motion was visible and the other leaflet had escaped (Figure 1c). Hence, computed tomography was performed, revealing one particle in the right brachiocephalic artery (Figure 2a, 2b) and another in the left common iliac artery (Figure 2c, 2d).

OPEN IN VIEWER

Figure 2.

Computed tomography scan showing embolized fragments (a) in the right brachiocephalic artery (c) in the left common iliac artery; 3D computed tomography scan showing the shape of the fragments (b, d).

Hypoxia progressed rapidly (PaO₂ 47 mm Hg), and chest radiography revealed florid pulmonary edema. The patient was transferred to the intensive care unit, intubated and mechanically ventilated. Intra-aortic balloon pumping was immediately started via the right femoral artery. However, the patient's condition deteriorated progressively and he was shifted to the operating room for emergency surgery.

A cardiopulmonary bypass was established and hypothermia was started. After clamping, the mitral valve was exposed via the transseptal approach. The site of the mitral valve implantation was well healed but one leaflet was missing. The valve was excised and the remaining leaflet started moving smoothly. There were no obvious signs of thrombus formation. The valve was replaced with a 29-mm St. Jude (St. Jude Medical, St. Paul, MN, USA) mechanical valve. Esophageal temperature was lowered to 28 °C with subsequent accomplishment of circulatory arrest. The right brachiocephalic artery was opened and the fragment was removed (Figure 3a, 3b).

OPEN IN VIEWER

Figure 3.

The explanted Edwards-Duromedics mitral valve (a) no obvious signs of thrombus formation; (b) Escaped leaflet removed from the right brachiocephalic artery; (c) escaped leaflet fractured in two pieces; (d) Edwards Duromedics mitral valve removed from the arterial system.

The patient had a good recovery. The other fragment in the left common iliac artery was removed via a retroperitoneal approach 3 weeks following valve replacement (Figure 3c, 3d). Postoperative course was uneventful and the patient was discharged from the hospital 10 days later.

Discussion

The cause for the dislodgement of the disc in this case was valve fracture. The five factors that may contribute to leaflet damage of the ED prosthetic valve have been identified. ⁶ Five months prior to this incident, cinefluoroscopy showed an asymmetrical motion of the leaflet (Figure 1a, 1b). This resulted in an asymmetrical closure wherein the intact leaflet closed with a higher impact, thereby causing one-sided leaflet damage. Our clinical experience is in agreement with the identified factors and the previously reported findings of the asymmetric annular lesions in the conflicting area. ³

Computed tomography is useful in locating escaped leaflets. Three-dimensional computed tomography aids in defining the shape of the fragment. The most commonly reported location of the escaped leaflet is between the aorta and the femoral artery. ^{2 –7} In this case, while one leaflet fragment was in the left common iliac artery, where it is usually found, the other fragment was located in the right brachiocephalic artery. Therefore, we removed the leaflet in the brachiocephalic artery under circulatory arrest during the same procedure. In order to decide the operative procedure and the canulation site for IABP, we believe that it is important to determine the location of the escaped leaflet nprior to the operation.

All patients receiving an ED prosthesis valve must be warned of the possibility of leaflet escape. In particular, they must be warned that asymmetrical motion of the valve may cause leaflet fracture.