Twenty-six patients presenting with 28 instances of massive acute thrombotic obstruction of a prosthetic valve (16 mitral, 12 aortic) were treated with fibrinolytic agents. In 15 cases the patient presented with acute pulmonary edema and low cardiac output, in 10 with congestive heart failure and embolism and in 3 with peripheral embolism only. The diagnosis of thrombotic obstruction was made by echocardiography or cineradiography, in patients in whom the disc was immobile or barely moving; cineangiography was necessary in only four patients. The fibrinolytic agents administered were streptokinase, 2,000,000 U for 10 hours (14 cases), urokinase, 4,500 U/kg per h for 12 hours (7 cases), or the two agents successively (7 cases). Fibrinolysis was entirely successful in 19 patients: 18 are alive and well without surgical intervention after follow-up of 6 to 64 months and 1 patient had surgical revision after fibrinolysis. In two patients, fibrinolytic treatment was apparently successful but obstruction recurred 4 and 19 months later, respectively, and the patients were again treated by fibrinolysis. In two patients complete failure of fibrinolytic treatment led to emergency surgery, and in three patients improvement was incomplete and death occurred shortly after treatment. No hemorrhagic complications were observed, but there were five cases of embolism during the fibrinolytic treatment. Fibrinolytic treatment would seem to be an attractive, nonsurgical alternative for the thrombosis of a valve prosthesis but, because of the risk of embolism with possible permanent damage, its use should be reserved for critically ill patients who are too sick to undergo immediate surgery.

The aim of this study was to investigate the mechanisms of the cardiodepressive action of ionic and non-ionic contrast media currently used in coronary arteriography. Experiments carried out on isolated preparations of cat papillary muscle, treated with increasing concentrations of Telebrix 39, Radioselectan, Hexabrix and Iopamidol 370 and 300, on the one hand and, on the other hand, a pre-determined dose of Telebrix and Iopamidol 300 during hypoxia and subsequent reoxygenation, showed that, at constant Ca2+ concentrations: (1) The cardiodepressive effects of contrast media are correlated with the hyperosmolality that they induce. When osmolality was higher than 400 mOsm, all the products caused a reduction of the peak force (PF: 40.49 +/- 5.15%), the maximum velocity of contraction (Vmax: 39.85 +/- 3.66%) and of the peak velocity of relaxation (Vrelax: 23.30 +/- 2.20%) (P less than 0.01). The time to peak force (TPF), on the other hand, remained constant, whereas the half-relaxation time (THR) was increased. No significant differences were observed between these effects and those induced by control iso-osmolar solutions when the same osmolality was induced. In practice, however, the critical hyperosmolality value of 400 mOsm is never reached when using non-ionic contrast media such as Hexabrix and Iopamidol 300. This could explain the excellent tolerance to these substances. (2) During hypoxia and reoxygenation, the effect of hyperosmolality is more marked. Thus, the non-ionic contrast medium, Iopamidol 300 (340 mOsm), reduces the hypoxic contractility depression (PF: 53.10 +/- 2.60% compared to the control values of 47.60 +/- 5.00%, P less than 0.01), whereas, at the same dose, the ionic medium Telebrix is hyperosmolar (440 mOsm) and induces a more pronounced hypoxic depression of contractility (P less than 0.01). The critical hyperosmolality is never reached during ventriculography (320 mOsm), whatever the medium used, but it can be observed during coronary arteriography. It is, therefore, important to use non-ionic contrast media in the investigation of unstable angina and of acute myocardium infarction.

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