Traumatic Injury to the Heart Due to Blunt Force

Non-penetrating injuries of the chest wall can give rise to a variety of cardiac lesions. The extent of cardiac damage depends on the intensity of the injury and on pre-existent disease of the heart. In the majority of cases there is a direct blow to the anterior chest wall but serious myocardial damage has been produced by blows directed against the posterior chest wall and abdomen. The crushing chest accidents account for a large number of reported cases but a blow in the precordium with fist, cricket ball, hockey ball, baseball and kick by a powerful animal can produce heart injury. There may or may not be an associated fracture of the ribs; greater cardiac damage seems to occur in patients without associated fracture of the ribs.l It is difficult to assess the exact incidence of cardiac injury as most patients with minor damage pass unnoticed or there is reluctance to make the diagnosis. The post-mortem incidence of cardiac involvement in instances of blunt trauma to the chest is i8 to 26 per cent.2 A frequent cause of cardiac injury is " steering wheel " accidents. The pericardium and myocardium are most frequently inijured but valves and their attachments have also been torn following blunt trauma to the chest wall. Contusion of the pericardium passes unnoticed as it rarely produces any signs and symptoms. Myocardial damage may amount to superficial contusion of any chamber of the heart, it may be partial laceration with or without injury to the coronary vessels or it may produce complete rupture of one or more chambers of the heart with instananeous death. Bright and Beck3 have collected 13 cases with perforation of the interventricular septum and one case of rupture of the inter atrial septum. It is quite possible that, in rare instances, the initial tear may involve the endocardium4 only with subsequent development of an aneurysm and delayed rupture of the heart. There are well authenticated cases in the medical literature of rupture of normal heart valves as a result of blunt injury to the chest wall. The aortic valve is most frequently affected and injury to the mitral valve includes tear of the chordae tendinae more commonly, tear of the valve cusps itself and occasionally tear of a papillary muscle.6 The anterior aspect of the heart is injured most frequently, which is in direct relation to the site of the mechanical force, but the posterior aspect of the heart may be bruised by squeezing against the vertebral column. The sudden increase of the intracardiac pressure produced by mass displacement of the blood towards the heart can cause tearing of the valves and their attachments, rupture of the auricles and in rare cases of the ventricles.7 The delayed rupture of the heart has been known to occur'and the usual time is 7-I4 days after injury. It usually follows deep contusion (or infarction) of the wall with subsequent softening and rupture.8 The delayed rupture of the chordae tendinae has not been reported before, this is especially liable to happen if the papillary muscles or chordae tendinae have been traumatised at the time of the original injury and the onset of rapid auricular fibrillation a few days later produces a marked strain on the already weakened valve attachments, leading to their rupture. The case history of a patient is presented who sustained injury to the heart following a crushing injury to the chest.