CardiacTrauma¶

Chapter 283 | Part 6: Disorders of the Cardiovascular System · Part 6 – Cardiovascular Disorders · Chapter 283

Key Clinical Points¶

Metastatic cardiac tumors are much more common than primary cardiac tumors.
Rapid deceleration in motor vehicle accidents can cause significant cardiac injury even without external signs of trauma.
A normal troponin level at 6–8 h after chest trauma essentially excludes blunt cardiac injury (BCI).
Penetrating cardiac injury with hemodynamic instability is a surgical emergency requiring immediate resuscitation and thoracotomy.
Gunshot wounds have much lower survival rates (20%) compared to knife wounds (65%) in penetrating trauma due to more frequent multichamber injury.
The right ventricle (RV) is the most frequently injured chamber in penetrating trauma due to its anterior position.
Commotio cordis is an electrical phenomenon occurring during repolarization, not a structural myocardial injury.
Primary cardiac lymphoma is the most chemotherapy-sensitive cardiac malignancy (~40% long-term survival).
Pericardiocentesis for tamponade is a temporizing measure; refractory cases may require a surgical pericardial window.
Approximately 20% of patients with stable penetrating chest injuries may have occult cardiac trauma (e.g., shunts or valvular regurgitation).

1. DEFINITION & OVERVIEW¶

• Cardiac Trauma: Categorized by mechanism of injury. • Blunt Cardiac Injury (BCI): Nonpenetrating trauma, often from rapid deceleration or chest impact. • Penetrating Cardiac Injury: Resulting from knife or bullet wounds; entry site is usually obvious. • Cardiac Tumors: • Metastatic: Much more common than primary tumors. They may occur via hematogenous/lymphangitic spread or direct invasion. The pericardium is most often involved, followed by myocardial involvement of any chamber, and rarely endocardium or cardiac valves. • Primary: Rare; Primary cardiac lymphoma is the most chemotherapy-sensitive cardiac malignancy (~40% long-term survival). Cardiac lymphosarcomas may respond to combined chemo- and radiotherapy.

2. EPIDEMIOLOGY¶

• Metastatic Tumors: • Only ~10% are clinically apparent; they are rarely the cause of presentation or death. • High relative incidence in malignant melanoma, leukemia, and lymphoma. • Most common primary sites: Breast and lung carcinomas. • Blunt Cardiac Injury (BCI): • Most common in motor vehicle accidents. • Also seen in falls, crush injuries, blast injuries, and sports. • Commotio Cordis: Most common in adolescents during sporting events.

3. ETIOLOGY & PATHOPHYYSICOLOGY¶

• Blunt Cardiac Injury (BCI): • Mechanism: Rapid deceleration or direct impact. • Pathology: Myocardium is pathologically similar to infarcted myocardium. • Commotio Cordis: • Mechanism: Electrical phenomenon caused by chest wall impact during the susceptible phase of repolarization (just before the peak of the T wave). • Aortic Rupture: • Mechanism: Deceleration injury, typically above the aortic valve or at the ligamentum arteriosum. • Clinical Note: May result in a pseudo-aneurysm if contained by the adventitia. • Tumor Pathogenesis: • Metastatic spread via hematogenous/lymphangitic routes or direct invasion. • Predominantly involves pericardium, followed by myocardial involvement.

4. CLINICAL FEATURES¶

• Metastatic Tumors: • Symptoms: Dyspnea, acute pericarditis, cardiac tamponade, ectopic tachyarrhythmias, heart block, and CHF. • Presentation reflects tumor size/location rather than histology. • Blunt Cardiac Injury (BCI): • Symptoms: Chest pain (often musculoskeletal), ECG abnormalities (Sinus tachycardia, RBBB, heart block, ST-T wave changes). • Specific Signs: Low QRS voltage and electrical alternans (suggestive of large pericardial effusion). • Penetrating Cardiac Injury: • Presentation: Rapid clinical deterioration, hemopericardium, tamponade, or massive hemorrhage. • Occult Injury: • ~20% of patients are stable at presentation but develop new murmurs or heart failure days/weeks later due to shunts or valvular regurgitation. • Aortic Rupture: • Signs: Increased pressure/pulse in upper extremities, decreased in lower; mediastinal widening on X-ray.

5. DIFFERENTIAL DIAGNOSIS¶

• Mimickers of Cardiac Trauma: Myocarditis, pericarditis, radiation/chemotherapy-induced cardiomyopathy, musculoskeletal trauma. • Mimickers of BCI: • Commotio cordis (electrical vs. structural). • Takotsubo syndrome (catecholamine-mediated). • Aortic dissection. • Iatrogenic Injuries: Must be distinguished from other penetrating traumas; typically have better prognosis due to rapid intervention.

6. INVESTIGATIONS & DIAGNOSIS¶

Diagnostic Criteria & Thresholds: • Troponin Timing: A normal troponin level at 6–8 h after chest trauma essentially excludes blunt cardiac injury (BCI). • Pericardiocentesis Cytology: Sensitivity of 67–92% for identifying malignant pericardial effusions.
Imaging Modalities: • Transthoracic Echocardiogram (TTE): Standard tool to identify: • Focal wall motion abnormalities or hematoma (most commonly RV free wall, LV apex, and interventricular septum). • Valvular insufficiency (most commonly mitral/tricuspid; occasionally aortic). • Pericardial effusion and tamponade. • Transesophageal Echocardiogram (TEE): Used if TTE images are inadequate. • Cardiac MRI: Primary tool for evaluating metastatic tumors and general cardiac tumors. • Angiography: Rarely necessary; used to delineate discrete myocardial lesions.

7. MANAGEMENT & TREATMENT¶

Metastatic Tumor Management: • Palliative Care: Standard for advanced malignant disease. • Pericardiocentesis: For symptomatic pericardial effusions. • Surgical Window: Creation of a pericardial window for refractory/recurrent pericardial effusion to prevent tamponade. • Sclerosing Agents: Bleomycin (with 3–5 days of drainage) for terminally ill patients.
Blunt Cardiac Injury Management: • Troponin Monitoring: Normal serial troponins indicate a low likelihood of sustained cardiac injury. • Emergency Intervention: Immediate surgical management for myocardial rupture or coronary artery laceration causing tamponade.
Penetrating Cardiac Injury Management: • Hemodynamic Instability: Surgical emergency requiring immediate resuscitation and thoracotomy. • Pericardiocentesis: Used as a temporizing measure for tamponade.

8. PROGNOSIS & COMPLICATIONS¶

Survival Rates (Penetrating): • Gunshot wounds: 20% survival. • Knife wounds: 65% survival. • Note: Difference is due to gunshot wounds more frequently causing multichamber injury.
Complications: • Late Complications: Approximately 20% of patients with stable penetrating injuries may present days or weeks later with new murmurs or heart failure (due to shunts, valvular regurgitation, or fisturus). • Surgical Risks: Pericardial constriction following hemorrhage; arteriovenous fistulas leading to high-output heart failure.

9. SPECIAL CONSIDERATIONS¶

Iatrogenic Injuries: • Context: Procedures like catheter placement, pacemaker leads, or RV endomyocardial biopsies. • Prognosis: Better than other penetrating trauma due to limited injury and rapid availability of corrective therapies.
Sports & Adolescents: • Commotio Cordis risk in sports (baseball, hockey, football). • Requires prompt defibrillation.

10. KEY PEARLS & CLINICAL TRAPS¶

• Troponin Timing: A normal troponin at 6–8 h is the definitive window for excluding BCI. • RV Vulnerability: The RV is the most common site of injury in penetrating trauma due to its anterior position. • Commotio Cordis: This is an electrical phenomenon; no structural damage is present. • Pericardiocentesis: Always a temporizing measure for tamponade, not a definitive treatment. • Symptom Awareness: 20% of stable penetrating trauma patients will develop mechanical complications later.

Reference Tables¶

TABLE 283-1 Spectrum of Cardiac Abnormalities Following Blunt Cardiac Injury¶

Harrison's 22e, p.2088

ABNORMALITY	COMMENTS
ECG abnormalities	Sinus tachycardia, RBBB, heart block, ST-T wave abnormalities, atrial and ventricular arrhythmias
Focal wall motion abnormality or hematoma	Most commonly involving RV free wall, LV apex, and interventricular septum
Myocardial rupture	Ventricular septal defect or free wall rupture
Pericardial effusion and tamponade	Resulting from free wall rupture or coronary artery laceration