Abstract Body (Do not enter title and authors here): DESCRIPTION OF CASE:
A 33-year-old previously healthy male presented with profound shock following a motor vehicle accident. Initial trauma workup revealed a sternal fracture and a large retrosternal hematoma in the anterior mediastinum measuring 1.4 x 4.1 x 14.0 cm along with right fourth and fifth anterior rib fractures. Imaging was negative for aortic dissection.

On examination, he was found to have a loud holosystolic murmur at the left lower sternal border. TTE revealed a large muscular, non-restrictive ventricular septal defect (VSD) with predominant left-to-right shunt, a dilated and hypokinetic right ventricle, and no pericardial effusion. Cath confirmed a 2:1 left-to-right shunt, elevated filling pressures, RV failure, and normal coronaries.

Given the presence of hemodynamic instability and VSD-related RV failure, cardiac surgery and interventional cardiology teams recommended Emergent VSD repair and temporizing mechanical circulatory support (MCS). An Impella CP device was successfully placed via the right femoral artery. The patient was stabilized for potential surgical repair and transferred to higher level of care for emergent VSD repair where he underwent surgical repair and was eventually taken off the MCS.

DISCUSSION:
Traumatic ventricular septal defect (VSD), first described by Hewett in 1847 remains a rare but serious complication of blunt chest trauma - Parmley et al. reported only 5 cases among 5,467 patients in a 1958 review. It typically results from anteroposterior compression during early systole, when the ventricles are full and AV valves closed, stressing the septum. Most occur in the muscular septum near the apex, as in our patient. Prognosis correlates with defect size and shunt severity - Rotman et al. reported 25% mortality in defects <2 cm, rising to 71% in larger ones. A Qp:Qs ratio >2:1, as in our patient, indicates a significant left-to-right shunt and warrants urgent intervention, especially with right heart failure or poor perfusion signs. Smaller, asymptomatic defects may be managed conservatively, as many close spontaneously. However, larger or symptomatic VSDs, especially those diagnosed within 48 hours post-injury, are associated with higher mortality and typically necessitate surgical or percutaneous closure. In addition, this case highlights the importance of thorough physical exam and high clinical suspicion for traumatic VSD in trauma patients with unexplained shock or new murmurs, especially with chest wall injuries.