Anticoagulants and Mitral Valvotomy.

Prophylactic anticoagulant treatment prior to mitral valvotomy was first recommended by Storm and Hansen (1955). Several authors have since confirmed that this measure significantly reduces the incidence of operative and post-operative embolism. But this dreaded complication was entirely abolished only in Storm and Hansen's series and in the first series reported by Miscall et al. (1962). In all other series (Table I) a few patients had an embolic episode despite the use of anticoagulants. This failure has resulted in reluctance to introduce anticoagulant prophylaxis. The question arises as to whether anticoagulants inevitably fail to prevent embolism in some patients (McDevitt et al., 1958) or whether failures are due to errors in management and are thus preventable. The detailed management of those patients in whom prophylaxis failed is not reported except in the series of Uglov and Potashov (1962) and Miscall et al. (1962), when insufficient reduction of the prothrombin time is mentioned. The criteria for satisfactory prophylactic anticoagulant treatment are difficult to define since the requirements of an adequate pre-operative regime have not yet been agreed. The management of anticoagulants has been evolved from the personal experience of each author, and their recommendations differ widely. The minimum period of pre-operative anticoagulation, the level of the prothrombin time, and the need for stopping anticoagulants before operation, are among the controversial issues. A period of pre-operative anticoagulation of three weeks was used by Miscall et al. (1962); four weeks or more were recommended by Beaumont, Moeri, and Len6gre (1957), Ricordeau and Balansa (1957), and Dahlgren and Bjork (1962); whereas Storm and Hansen (1955)