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Traumatic heart disease


1

What is the most common cause of cardiac injury?

  • Motor vehicle accidents are the most common cause of cardiac injury.

2

List the physical mechanisms of injury in cardiac trauma.

  • Physical mechanisms of injury include penetrating trauma (i.e., ribs, foreign bodies, sternum), nonpenetrating trauma (or blunt cardiac injury), massive chest compression (or crush injury), deceleration, traction, or torsion of the heart or vascular structures, and sudden rise in blood pressure caused by acute abdominal compression.

3

What is myocardial contusion?

  • Myocardial contusion is a common form of blunt cardiac injury; it is considered a reversible insult and is the consequence of a nonpenetrating myocardial trauma. It is detected by elevations of specific cardiac enzymes with no evidence of coronary occlusion and by reversible wall motion abnormalities detected by echocardiography. It can manifest in the electrocardiogram (ECG) by ST-T–wave changes or by arrhythmias. Areas of myocardial necrosis and hemorrhagic infiltrates that can be recognized on autopsy characterize myocardial contusion.

4

Which major cardiovascular structures are most commonly involved in cardiac trauma?

  • Cardiac trauma most commonly involves traumatic contusion or rupture of the right ventricle, aortic valve tear, left ventricle or left atrial rupture, innominate artery avulsion, aortic isthmus rupture ( Fig. 72.1 ), left subclavian artery traumatic occlusion, and tricuspid valve tear.

    Fig. 72.1, Traumatic rupture of the descending thoracic aorta (arrows) at the aortic isthmus.

5

What bedside findings can be found in patients with suspected major cardiovascular trauma?

  • Obvious clinical signs in patients with nonpenetrating trauma are rare. However, a bedside evaluation by an astute clinician to detect possible life-threatening cardiovascular and thoracic complications can reveal important signs in just a few minutes ( Table 72.1 ).

    Table 72.1
    Important Signs of Cardiovascular and Thoracic Trauma
    FINDING SUGGESTED LESIONS
    Pale skin color, conjunctiva, palms, and oral mucosa Suggests important blood loss
    Decreased blood pressure in the left arm Seen in patients with traumatic rupture of the aortic isthmus, pseudocoarctation, or traumatic thrombosis of the left subclavian artery
    Decreased blood pressure in the right arm Consider innominate artery avulsion
    Subcutaneous emphysema and tracheal deviation Consider pneumothorax
    Elevated jugular venous pulse with inspiratory raise (i.e., Kussmaul’s sign) Suggests cardiac tamponade or tension pneumothorax
    Prominent systolic V wave in the venous pulse examination Suggests tricuspid insufficiency as a result of tricuspid valve tear
    Nonpalpable apex or distant heart sounds Suspect cardiac tamponade
    Pericardial rub Diagnostic for pericarditis
    Pulsus paradoxus Seen in patients with cardiac tamponade, massive pulmonary embolism, or tension pneumothorax
    Continuous murmurs or thrills Consider traumatic arteriovenous fistula or rupture of the sinus of valsalva
    Harsh holosystolic murmur Suspect traumatic ventricular septal defect
    Early diastolic murmur and widened pulse pressure Suspect aortic valve injury
    Cervical and supraclavicular hematomas Seen in traumatic carotid rupture
    New focal neurological symptoms Traumatic carotid, aortic or great vessel dissection

6

Can an acute myocardial infarction complicate cardiac trauma?

  • Myocardial infarction is an unusual complication in patients with chest trauma. Chest trauma can injure a coronary artery, leading to myocardial infarction due to coronary spasm, thrombosis, laceration, or dissection of the arterial wall ( Fig. 72.2 ). Patients with underlying coronary artery disease have favorable pathophysiologic conditions to suffer an acute coronary syndrome during trauma as a result of limited coronary flow reserve, excess of circulating catecholamines, hypoxia, blood loss, and hypotension. It may be relevant in the appropriate clinical scenario to consider the possibility of cardiac syncope as the primary cause resulting in a traumatic event due to ventricular arrhythmias in a patient with an acute myocardial infarction and concomitant trauma. Chest trauma can elevate cardiac-specific enzymes without significant coronary stenosis; therefore, careful interpretation of these indicators in a trauma victim is warranted.

    Fig. 72.2, Traumatic coronary dissection showing a double lumen in the left anterior descending artery (white arrows) , extending retrograde and narrowing the lumen of the left main coronary artery (black arrow) in a patient with a high-speed motor vehicle accident.

7

What is the most common type of myocardial infarction suffered by trauma victims?

  • According to the universal definition of myocardial infarction, patients who have myocardial necrosis during trauma usually suffer a type 2 myocardial infarction. This type of myocardial injury is secondary to direct trauma or ischemia as a result of a relative imbalance of either increased myocardial oxygen demand and/or decreased myocardial oxygen supply (e.g., coronary artery spasm, coronary embolism, arrhythmias, hypertension, anemia, or hypotension), rather than coronary occlusion caused by advanced atherosclerosis or an acute coronary thrombotic event (type 1 myocardial infarction), and is characterized by a variable increase in cardiac biomarkers with no ischemic symptoms or ECG changes.

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