The severity of blunt cardiac injury is influenced by factors such as the velocity of the impact, the mass of the injuring object, the duration of force application, the phase of the cardiac cycle during impact, and the area and direction of force applied to the heart. Minor injuries may result in asymptomatic myocardial contusions, while more severe trauma can lead to cardiac rupture. Most patients with blunt cardiac rupture die at the scene of the incident. Only a very small number of cases may successfully reach the hospital through effective on-site emergency interventions. Myocardial contusion is the most common clinical manifestation, ranging in severity from minor injuries causing subepicardial to subendocardial myocardial hemorrhage and limited myocardial fiber disruption to extensive myocardial contusion, large-scale myocardial hemorrhage and necrosis, and even injuries to intracardiac structures, such as the valves, chordae tendineae, and the interventricular septum. Myocardial contusion may heal with scarring, potentially leading to complications such as ventricular aneurysm in the future. Severe myocardial contusion is often fatal due to profound arrhythmias or heart failure.
Clinical Presentation and Diagnosis
Mild myocardial contusion may be asymptomatic, while moderate to severe contusions can result in symptoms such as chest pain, palpitations, dyspnea, and even angina-like presentations. Patients may also have evidence of anterior chest wall soft tissue damage or sternal fractures. The diagnosis of myocardial contusion relies primarily on the clinician's awareness and vigilance, emphasizing the importance of comprehensive interpretation of auxiliary test results. Common auxiliary tests include:
- Electrocardiogram (ECG): Findings may include ST-segment elevation, flattened or inverted T waves, atrial or ventricular premature beats, or tachyarrhythmias.
- Echocardiography: Abnormalities in cardiac structure and dysfunction in the segments of the contused myocardium can be identified, with transesophageal echocardiography offering higher sensitivity for detecting myocardial contusion.
- Myocardial Enzyme Studies: Dynamic monitoring of changes in the activity of blood markers such as creatine kinase and its isoenzyme (CK, CK-MB), as well as lactate dehydrogenase and its isoenzymes (LDH, LDH1, LDH2), provides useful information. Measurements of cardiac troponin I (cTnI) or T (cTnT) offer higher specificity in detecting myocardial injury.
Management
Early strict monitoring is important for patients with myocardial contusion. Adequate rest, oxygen supplementation, and pain relief must be ensured. Preventing potentially fatal complications, such as arrhythmias and heart failure, is crucial; these complications generally occur early after the injury, although delayed presentations are also possible. Patients with hemodynamic instability, abnormal ECG findings, or elevated myocardial biomarkers require careful monitoring and treatment.