Electrocardiography of traumatic heart disease

General Principles

 * 1) Injury may be divided in to penetrating and non-penetrating.
 * 2) Presentation depends upon the location of the injury and the cardiac structures involved.
 * 3) EKG is usually not as helpful as the physical exam and the CXR in the evaluation of penetrating injuries.
 * 4) In the evaluation of non-penetrating injuries, the EKG is helpful.

Non-Penetrating Injuries
Causes
 * 1) MVA. Most common cause. Heart can be compressed between the sternum and the spine.
 * 2) Sudden acceleration and deceleration.
 * 3) Fist, a kick, a blunt object or an animal.
 * 4) Cardiopulmonary Resuscitation (CPR).
 * 5) Serious damage may be present in the absence of fractures.

Potential Damage

 * 1) Pericardium
 * 2) * disruption
 * 3) * hemopericardium and tamponade
 * 4) * pericarditis
 * 5) Myocardium
 * 6) * contusion
 * 7) * rupture
 * 8) * septal perforation
 * 9) * late aneurysm
 * 10) Valves
 * 11) * chordae tendineae
 * 12) * papillary muscle rupture
 * 13) Coronary arteries
 * 14) * contusion
 * 15) * thrombosis

Potential EKG Changes

 * 1) ST and T wave changes
 * 2) * the most common change (17 to 58%)
 * 3) * develop within 24 to 48 hours of the injury and mimic the changes due to myocardial ischemia.
 * 4) * in most, the changes are transient, but they may persist.
 * 5) * myocardial contusion or traumatic pericarditis is the usual underlying abnormality.
 * 6) * if the abnormality persists, then extensive myocardial scarring may be present.
 * 7) * CK MB and technetium-99 pyrophosphate scintigraphy have been found to be even less sensitive than the EKG in the diagnosis of myocardial contusion.
 * 8) Reduction of QRS voltage
 * 9) * suggests effusion, possible tamponade
 * 10) Pseudoinfarction pattern
 * 11) * rare
 * 12) IVCD
 * 13) * reported to be as high as 23% in one series, "Chou feels this is an overestimate"
 * 14) * RBBB is the most common abnormality
 * 15) SVTs and VT
 * 16) * VF may be responsible for sudden death

Electrical Injury

 * 1) Sudden death due to electrocution is usually secondary to VF or cardiac standstill.
 * 2) The heart s most sensitive to a low frequency current of 40 to 60 cycles/second
 * 3) Current flow causes tissue coagulation by heat damage.
 * 4) Damage is proportional to voltage, resistance of the tissue, and the duration of the flow.
 * 5) EKG abnormalities are present in 10 to 46% of patients with electrical injury.
 * 6) Arrhythmias (a. fib, VT, VF) may appear hours after the injury and may be recurrent for several months.
 * 7) ST segment changes and T wave changes some of which resemble those of myocardial ischemia or injury may occur.
 * 8) The QT interval may prolong.
 * 9) Pseudoinfarct patterns have been observed.