pressure will decrease, causing a narrowing of the pulse pressure and subsequent hypotension and cardiogenic shock Clinical Considerations Clinical Recognition Blunt cardiac injury occurs more commonly with other associated injuries than in isolation Unlike adults, pediatric patients with blunt cardiac injury often have few presenting signs or symptoms In one pediatric study, less than half of the awake patients with blunt cardiac injury complained of chest pain, and external evidence of thoracic injury was present in only 60% of these patients In the same study, cardiac examination was abnormal in less than one-quarter of the patients Additional findings that should prompt evaluation for cardiac injury include a cardiac arrhythmia, a new murmur, or evidence of congestive heart failure (e.g., an enlarged liver, a gallop heard on cardiac examination, or rales with auscultation of the lungs) Myocardial contusion, ventricular or atrial rupture, and valvular disruption may produce cardiogenic shock Circulatory compromise results from a decrease in cardiac output, usually from impaired myocardial contractility Pericardial tamponade, due to air or blood inside the pericardium, will also decrease cardiac output and cause circulatory collapse If the patient is decompensating and a pericardial tamponade is suspected, a pericardiocentesis should be performed emergently and prior to any further diagnostic evaluation, with the exception of bedside US when available to confirm the diagnosis and facilitate the procedure ( Fig 115.5 ) Triage Children with blunt trauma to the sternum or left hemithorax from a high-energy mechanism should be placed on a cardiac monitor and evaluated immediately While the stable patient is unlikely to deteriorate, providers should be prepared to correct any arrhythmias by both pharmacologic and electrical means Signs of cardiogenic shock should be addressed immediately by rapid evaluation and correction of the cause Initial Assessment Patients with cardiac injuries may complain of chest or sternal pain Physical examination may reveal tachycardia, an irregular heart rhythm, a new heart murmur, signs of congestive heart failure, or in the case of cardiac tamponade, muffled heart tones As previously noted, however, many children with blunt