Complete Heart Block and Echocardiographic Abnormalities Caused by Pyrotechnic Chest Trauma

Excerpt

A 2-year-old boy, who was attending an amateur pyrotechnic show, was standing 15 feet from a mortar-type firework assembly (i.e., fuse-lit polyethylene firing pipe, in which lies the shell and propellant) when the tubing tipped over and fired the explosive horizontally. The projectile hit the patient directly in the chest, throwing him through the air and rendering him unresponsive. The mortar did not detonate. He was rushed to a pediatric tertiary care center, where vital signs showed a heart rate of 70 bpm and blood pressure of 117/72 mmHg. The patient was awake and crying intermittently with no significant increase in heart rate while upset. He had an 8-cm hematoma to the right of mid-sternum, and his cardiac examination was notable for a quiet precordium without an audible murmur. Laboratory findings included creatine phosphokinase-MB 333 ng/ml (normal 0 to 3 ng/ml), troponin >50.0 ng/ml (normal <0.4 ng/ml), and brain natriuretic peptide 455 pg/ml (normal 100 pg/ml). An electrocardiogram (ECG) demonstrated complete atrioventricular block with an atrial rate of 135 bpm and a junctional escape rhythm of 67 bpm (Fig. 1 [ECG]).

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