Thrombosis of prosthetic heart valves: diagnosis and therapeutic considerations

Abstract

P rosthetic valve thrombosis (PVT) is a rare but serious complication of valve replacement, most often encountered with mechanical prostheses. The significant morbidity and mortality associated with this condition warrants rapid diagnostic evaluation. However, diagnosis can be challenging, mainly because of variable clinical presentations and the degree of valvular obstruction. Cinefluoroscopy (for mechanical valves) and transthoracic and transoesophageal echocardiography represent the main diagnostic procedures.Although surgical treatment is usually preferred in cases of obstructive PVT, optimal treatment remains controversial. The different therapeutic modalities available for PVT (heparin treatment, fibrinolysis, surgery) will be largely influenced by the presence of valvular obstruction, by valve location (left-or right-sided), and by clinical status. Hence, treatment of an obstructive left-sided PVT will differ from that of non-obstructive or right-sided PVT. The purpose of this article is to review the physiopathology, diagnosis and treatment of PVT and to provide recommendations for management. EPIDEMIOLOGY c Mechanical valve thrombosisThe incidence of obstructive PVT for mechanical valves varies between 0.3-1.3% patient years. 1 Thromboembolic complications, including systemic emboli, are more frequent and occur at a rate of 0.7-6% patient years. Non-obstructive PVT is a relatively frequent finding in the postoperative period, 2 with a reported incidence as high as 10% in recent transoesophageal echocardiography (TOE) studies. Although these are usually small non-obstructive thrombi, they underline the necessity of optimal anticoagulation in the postoperative period. According to a series of surgical interventions for PVT, the first postoperative year is marked by a 24% incidence of thrombosis, with a stable incidence between the second to fourth years of approximately 15%, with a subsequent decrease thereafter. 3Bioprosthetic valve thrombosis Thrombosis of a bioprosthetic valve 4 is a rare occurrence when compared to mechanical prostheses. Bioprosthetic PVT is usually diagnosed in the early postoperative period, when endothelialisation of the suture zone is not yet complete. Hence, this has led to the recommendation of anticoagulating patients with bioprostheses for the first three months postoperatively, particularly for mitral prostheses. PHYSIOPATHOLOGY Predisposing factorsAccording to Virchow's triad, factors predisposing to thrombus formation can be divided into endothelial, haemodynamic and haemostatic factors.5 Endothelial factors represent biocompatibility of the prosthesis itself and interaction between the prosthesis and the suture zone. Tissue cicatrisation and endothelialisation characteristically require a few weeks to be complete. Haemodynamic factors include both haemodynamic characteristics of the prosthesis, as well as overall cardiac haemodynamic status. Although the profile of new generation mechanical bileaflet valves is largely superior to that of earlier generation prostheses (and ...

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“…With respect to the treatment strategy of BPVT, it depends on clinical presentation, the patient's hemodynamic status, the presence of valvular obstruction and the prosthesis location [6]. In hemodynamically unstable patients, obstructive thrombosis or congestive heart failure, surgery is usually preferred as the first choice.…”

Stuck Mitral Bio-Prosthetic Valve

“…Valve thrombosis is a complication predominantly occurring with mechanical prosthetic valves, especially in the mitral position [1] . Valve thrombosis with bioprosthesis is rare [2] .…”

Successful mitral valve replacement in a young pregnant patient

“…The risk of valve thrombosis is quoted as being between 0.7% and 6% per patient per year (up to 1.3% for thrombosis). This risk may rise to 25% in the absence of adequate anticoagulation [1]. Herein, we present a young pregnant patient with stuck mitral valve due to valve thrombosis while receiving LMWH and who required re-replacement of mechanical prosthetic mitral valve.…”