Management of Thrombo-Embolism after Aortic Valve Replacement with the Björk-Shiley Tilting Disc Valve: Medicamental Prevention with Dicumarol in Comparison with Dipyridamole—Acetylsalicylic Acid. Surgical Treatment of Prosthetic Thrombosis

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Abstract
Dicumarol anticoagulation proved very effective in the prevention of thrombo-embolic complications after aortic valve replacement with the Björk-Shiley tilting disc valve. We have, however, encountered six late deaths because of massive cerebral haemorrhage, which represent 3% of the patients who were maintained on dicumarol medication at that time. This unacceptable mortality prompted us to introduce two programmes, one without anticoagulation and another one with dipyridamole-acetylsalicylic acid. Furthermore, dicumarol was terminated in patients with haemorrhagic episodes, instable anticoagulation, pregnancy, and in those requiring surgery. the results were disappointing, however, and the majority of the patients involved were therefore put on dicumarol medication. Eleven of the 64 consecutive patients taking dipyridamole—acetylsalicylic acid had thrombo-embolic episodes during a mean follow-up period of 9 months. Without anticoagulation, 3/27 patients were affected during 6 months and 5/32 during 12 months when dicumarol was stopped. the risk of thrombo-embolism in these three groups, expressed as the incidence per patient month, corresponded to 0.019, 0.019 and 0.013 in that order. in comparison, there was only one episode of thrombo-embolism in 138 patients who were maintained on dicumarol for an average period of 30 months, a risk less than 0.0003 or 50 times lower than that in the other groups. Thrombo-embolism never occurred with adequate anticoagulation. Temporary absence or discontinuance of dicumarol, in comparison with such continuous medication, probably involved a higher long-term risk of developing thrombo-embolism. The mortality from cerebral haemorrhage, expressed as the incidence per patient month, was to date the same with and without dicumarol anticoagulation (0.001) and only one-third of the mortality due to thrombo-embolism without dicumarol (0.003). Furthermore, no other severe bleeding complications were found in the patients receiving long-term anticoagulation. This re-evaluation suggests a satisfactory management of anticoagulation and a low risk if the contraindications are taken into consideration. It was harmful to interrupt and totally omit this treatment. Long-term anti-coagulation is therefore recommended after aortic valve replacement with the Björk-Shiley prosthesis. Thrombotic encapsulation of the Björk-Shiley aortic prosthesis has hitherto been encountered in 7 patients, one of whom had a late recurrence. the symptoms of this highly dangerous complication are those of left ventricular failure caused by a marked thrombotic obstruction of its outflow. the absence of the typical “click” of the Björk-Shiley prosthesis and the presence of a loud systo-diastolic murmur at ausculation are diagnostic of malfunction of the prosthetic valve and indicate urgent re-operation. Thrombectomy was performed in 5/7 patients and was successful in all of them. It proved possible to clean out all the prosthetic deposits without removal of the disc, simply by stepwise rotation of the prosthesis within its sewing ring.