{'fraction_non_alphanumeric': 0.024166666666666666, 'fraction_numerical': 0.0125, 'mean_word_length': 5.388297872340425, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Hancock pericardial prosthesis. Intrinsic dysfunctions].

The frequency of primary dysfunction of 432 Hancock pericardial bioprosthesis was evaluated during a mean follow-up period of 53.1 months per patient. This frequency was 3.20% valve-year in mitral valve prosthesis and 0.92% valve-year in aortic valve prosthesis. Only one case of calcification was noted. Dysfunction was usually due to tearing of one or several pericardial cusps (25 cases), occasionally to tissue retraction (4 cases). Pathological examination of the explanted valves showed fibrin formation followed by organization into fibrous tissue in the host, retracting or fragilizing the pericardial valvular tissue. A preliminary study of the same group had led to discontinuation of Hancock prosthesis. The long follow-up period makes it possible to compare the results obtained with those of pericardial prosthesis of the same generation, to stress the need for echocardiographic monitoring of the implanted valves and to hope that new techniques of pericardial valve fitting will improve the mechanical reliability of prosthesis which, from the point of view of thrombogenesis and haemodynamics, have unquestionable advantages.