Lost And Found Catastrophic En Block Embolism of a Mechanical Prosthetic Valve Thrombus after Thrombolytic Therapy

with refractory pulmonary oedema secondary to a massive thrombosis of a St. Jude mechanical mitral prosthetic valve. She was noncompliant with warfarin and had suffered embolic stroke 3 years earlier, from which she had recovered. She was in sinus rhythm with absent valve clicks on auscultation. A transthoracic echocardiogram revealed a high transmitral peak gradient of 34 mmHg and a mean gradient of 27 mmHg with an ejection fraction of 55% [Figure 1A]. The international normalised ratio (INR) was 1.29. An urgent transesophageal echocardiogram (TEE) demonstrated a large (6 cm2) left atrial thrombus attached to the mechanical valve at the discs which were stuck in a closed position [Figures 1B and 1C]. The patient was advised to have emergency surgery, but she and the family refused. In spite of explaining the risks involved in thrombolysing a large clot, the patient and the family preferred thrombolytic therapy. As a life-saving measure, patient was thrombolysed with 10 units of reteplase intravenously over 2 minutes with a repeat dose of 10 units administered 30 minutes later. After an hour of thrombolysis a repeat TEE showed complete disappearance of the thrombus from the left atrium with one of the discs stuck in closed position [Figures 2 A and B]. The peak transmitral gradient was 7 mmHg and the mean gradient was 4 mmHg [Figure 2C]. Immediately, the patient started SQU Med J, May 2012, Vol. 12, Iss. 2, pp. 242-241, Epub. 9th Apr 2012 Submitted 26th Nov 11 Revision Req. 31st Jan 12, Revision recd. 8th Feb 12 Accepted 12th Feb

A 45-year-old woman presented with refractory pulmonary oedema secondary to a massive thrombosis of a St. Jude mechanical mitral prosthetic valve.She was noncompliant with warfarin and had suffered embolic stroke 3 years earlier, from which she had recovered.She was in sinus rhythm with absent valve clicks on auscultation.A transthoracic echocardiogram revealed a high transmitral peak gradient of 34 mmHg and a mean gradient of 27 mmHg with an ejection fraction of 55% [Figure 1A].The international normalised ratio (INR) was 1.29.An urgent transesophageal echocardiogram (TEE) demonstrated a large (6 cm 2 ) left atrial thrombus attached to the mechanical valve at the discs which were stuck in a closed position [Figures 1B and 1C].
The patient was advised to have emergency surgery, but she and the family refused.In spite of explaining the risks involved in thrombolysing a large clot, the patient and the family preferred thrombolytic therapy.As a life-saving measure, patient was thrombolysed with 10 units of reteplase intravenously over 2 minutes with a repeat dose of 10 units administered 30 minutes later.After an hour of thrombolysis a repeat TEE showed complete disappearance of the thrombus from the left atrium with one of the discs stuck in closed position [Figures 2 A and B].The peak transmitral gradient was 7 mmHg and the mean gradient was 4 mmHg [Figure 2C].Immediately, the patient started SQU Med J, May 2012, Vol. 12, Iss. 2, pp.242-241, Epub.9 th Apr 2012 Submitted 26 th Nov 11 Revision Req. 31 st Jan 12, Revision recd.8 th Feb 12 Accepted 12 th Feb Departments of 1 Cardiology, 2 Vascular Surgery, 3 Radiology, 4  The incidence of left-sided prosthetic valve thrombosis (PVT) ranges from 0.5% to 0.8% per patient-year. 1,2The mortality of obstructive PVT is about 10% irrespective of the treatment strategy. 1he American College of Cardiology/American Heart Association (ACC/AHA) and American College of Chest Physicians guidelines recommend fibrinolytic therapy as first-line treatment for patients in good functional class with low thrombus burden (< 0.8 cm 2 ) and in all other patients if they are considered to be at high risk for surgery. 3,4mergency surgery is reasonable for patients with a thrombosed left-sided prosthetic valve and New York Heart Association (NYHA) functional class III-IV symptoms or a large clot burden (> 0.8cm 2 ). 3,4urthermore, in the following groups of patients  surgery is advised, namely: 1) patients with large left atrial thrombus; 2) patients with any active bleeding or a history of intracranial bleeding; 3) patients with evidence of ischaemic stroke from 4 hours to six weeks, and 4) post-valve replacement within 4 days. 1The major complication of thrombolytic treatment for PVT is the risk of embolisation which occurs in 12-15% of the cases. 3A registry study demonstrated that thrombus size on TEE and a past history of stroke were independent predictors of complications as seen in this patient. 2Left atrial thrombi are also known to embolise at the time of, or shortly after a change in atrial rhythm. 5In this case, there was not only obstructive PVT, but it was associated with a large left atrial thrombus and hence surgery was the initial choice of treatment.However, the patient refused surgery and was thrombolysed with catastrophic embolism.

Figure 1 :
Figure 1: (A) Transthoracic echocardiography showing mean diastolic mechanical mitral valve transvalvular gradient of 27 mmHg and a peak gradient of 34 mmHg in a patient with prosthetic valve thrombosis.(B) Transesophageal echocardiography demonstrating stuck mechanical mitral valve with a large left atrial (LA) thrombus attached to the prosthetic valve (arrowheads).(C) Transesophageal echocardiography demonstrating close-up image of a large echogenic well defined LA thrombus attached to a mechanical prosthetic valve (arrowheads).

Figure 2 :
Figure 2: (A) Transesophageal echocardiography demonstrating disappearance of a large left atrial thrombus attached to a stuck mechanical valve after thrombolysis with reteplase.Note the bileaflet mechanical valve in closed position.(B) Transesophageal echocardiography demonstrating residual thrombus post-thrombolysis in a bi-leaflet mechanical valve with one of the disc immobile in closed position (arrowheads).Note the other disc is open.(C) Transesophageal echocardiography showing mean diastolic mechanical mitral valve transvalvular gradient of 4 mmHg and a peak gradient of 7 mmHg in a patient with prosthetic valve thrombosis treated with thrombolysis.LA, left atrium.

Figure 3 :
Figure 3: Contrast-enhanced computed tomography (CT) scan in axial (A) view showing presence of contrast in the right common iliac artery (arrowheads) with absence of opacification of left common iliac artery in a patient with prosthetic valve thrombosis treated with thrombolysis.Contrast-enhanced CT in three-dimensional reconstruction (B and C) demonstrates complete occlusion of left common iliac artery and right common femoral artery (arrowheads) in the patient with prosthetic valve thrombosis treated with thrombolysis.