Penetrating Heart-Wounds are not, however, invariably rapidly fatal; life being in some cases considerably prolonged, while it would even appear, in accordance with some observations selected from a large number of cases, that wounds of the heart may be occasionally followed by recovery. The fact that death does not immediately ensue has been explained on the ground of the narrow and oblique course of the wound, and by the different position and crossing of the various wounded layers of the muscular substance. In many cases the wound has been closed by some portion or the whole of the instrument, or even a fragment of a rib, remaining imbedded in it.

It is difficult to answer the question whether the rent occurs in spontaneous ruptures, during the systole or the diastole. Many (Pigeaux, amongst others) are of opinion, although without sufficient ground, that it generally takes place during the diastole. Judging by analogy with lacerations of the voluntary muscles, it must take place during the systole. In proof, however, of the frequency of its occurrence during the diastole, the fact might be advanced that the course of the rent in the heart, when contracting after the haemorrhage, is not straight, but angular or zigzag, in consequence of the disturbed position of the different muscular layers.

It is equally difficult to determine, generally or in any individual case, whether the rent has affected the whole thickness of the heart at once, or whether it has proceeded gradually, till it finally penetrated the whole thickness of the wall, and whether it began at the exterior or in the interior. According to our observations on this subject, the rent begins, in most cases, in the inner muscular layers. The laceration of a papillary muscle, or of a trabecula carnea, is of very rare occurrence, and the conditions on which it depends are probably the same as those of fissure of the heart's wall.

Laceration of the tendons of the papillary muscles and of the valves probably always depends on the relaxation and lacerability of the tissue, associated with inflammation of the lining membrane of the heart (endocarditis). It not unfrequently acquires importance by the valvular insufficiency to which it gives rise. Laesiones continui of the valves will be more fully considered in a future page.