Myocardial conducting system dysfunctions from thoracic impact.

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Trauma Biomechanics

Background:

• Blunt thoracic impacts can cause significant cardiac injury.
• Understanding the relationship between impact biomechanics and cardiac conduction system dysfunction is crucial for injury prevention.

Purpose of the Study:

• To analyze electrocardiogram (ECG) changes following blunt thoracic impacts in pigs.
• To identify biomechanical parameters correlated with cardiac conduction system trauma and ventricular fibrillation.
• To develop an injury severity classification for myocardial conducting system dysfunctions.

Main Methods:

• 12 anesthetized pigs underwent blunt thoracic impacts.
• Electrocardiograms (ECG lead II) were analyzed.
• Biomechanical response parameters (sternal acceleration, impact velocity, thoracic deflection, cumulative AIS, peak spinal acceleration, applied force) were measured.
• Correlation analysis was performed between biomechanical parameters and cardiac events.

Main Results:

• All pigs exhibited trauma to the heart conducting system.
• Ventricular fibrillation occurred in some animals, leading to demise in four.
• High sternal acceleration (930 g) and impact velocity (10.7 m/s) significantly correlated with ventricular dysfunction.
• Ventricular fibrillation initiation did not correlate with normalized thoracic deflection, cumulative AIS, peak spinal acceleration, or applied force.

Conclusions:

• Blunt thoracic impacts induce diverse cardiac conduction system injuries in pigs.
• Sternal acceleration and impact velocity are key predictors of ventricular dysfunction.
• A new myocardial conduction defect (MCD) classification system was developed for evaluating these injuries.