Changes in heart size after homograft replacement of aortic, mitral, or both aortic and mitral valves.

j-Ieart size was measured radiographically before and after single or double homograft valve replacement in 69 consecutive patients. Thirty patients had aortic valve replacement, 25 mitral, and 14 both aortic and mitral valve replacement. For aortic valve replacement a fresh unsupported homograft was inserted in the subcoronary position, while for mitral valve replacement afresh semilunar homograft was inserted into the left atrium. The cardiothoracic index and the maximum transverse diameter of the heart were measured preoperatively and at periods varyingfrom 3 to 19 months postoperatively. Allpatients who had homograft replacement of the aortic valve showed reduction in heart size compared to 88 per cent (22 out of 25) ofpatients after mitral valve replacement. The average reduction in cardiothoracic index was greatest after both aortic and mitral valve (i.e. double valve) replacement (Io07% of the original value), considerable after aortic valve replacement (9.2% of the original value), and least after mitral valve replacement (3.3% of the .-original value). These figures compare favourably with reported changes in heart size after insertion of pros*thetic valves. An attempt is made to explain the different responses of the heart size in three groups studied.