Mechanical Valve Thrombosis: A Tailored Approach for a Multiplex Disease

Over the years, progress in the design and structureof mechanical prostheses has led to a considerableimprovement in their hemodynamic features anddurability, such that they are now preferable to bio-prostheses in most cases (1,2). However, the use ofmechanical prostheses remains burdened with the riskof complications, amongst which thrombosis is themost dreaded (1). Valve thrombosis is still associatedwith a high mortality, even if emergency medical orsurgical treatment is promptly established (3). Thereported mortality rate of redo surgery is dependentupon the patient’s status at presentation, and rangesfrom 8 to 20% for urgent cases up to 37 to 54% for crit-ically ill patients (1,4,5). With the advent of new-gener-ation prosthetic valves and improvements in surgicaltechniques, the perioperative mortality rate and long-term results have been improved (6,7). Because of thehigh surgical risk associated with valve replacement,during the 1980s thrombolysis was proposed as analternative to surgery (4,8,9). Although the initialresults for thrombolysis were encouraging, studiesconducted in larger series of patients showed a signif-icant risk of neurological complications and recurrentthrombosis, and consequently surgery remained thetreatment of choice (8,9).Numerous studies have been carried out to identifythe risk factors for prosthetic thrombosis (1,3), and themost frequently reported is inadequate or discontin-ued anticoagulant therapy (3). Other risk factorsinclude previous endocarditis and the prosthetic valvemodel used, and while many authors have reported amajor incidence of thrombosis in tilting-disc valves (2),few data exist regarding the mechanisms of thisobstruction (10). Obstruction is most often thought toresult from valve thrombosis, but the role of chronicpannus formation in causing obstruction is less wellestablished (1,3) and the relationship between throm-bus and pannus formation has not been fully elucidat-ed.In this study, we reviewed the outcome of a series ofconsecutive patients suffering from mechanical valvethrombosis who had been treated either with surgeryor thrombolysis. This investigation was carried out tobetter define the indications for surgery or thromboly-sis in the treatment of prosthetic valve thrombosis.