. (1976). Thorax, 31,[332][333][334][335][336] (Emanuel, 1963). In general, it has been held that severe pulmonary hypertension was associated with greater operative risk, higher operative mortality, and a poorer long-term prognosis.However, a significant reduction in the level of pulmonary hypertension in some patients after mitral valve surgery and a more favourable longterm outlook have been reported (Dalen et al., 1967;Zener et al., 1972). Furthermore, Ward and Hancock (1975) suggested that extreme pulmonary hypertension should be regarded as a positive indication for early operation. In their series there was a high mortality in this group, but the prognosis was nonetheless considerably better than the natural history of the disease without surgical intervention. In our series in the last five years, only one of 16
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