Penetrating heart injuries can be lethal. Here we report a case of self-inflicted cardiac injury with glass fragments by a psychiatric patient. The patient presented with cardiogenic shock and was initially treated surgically for a large pneumothorax and cardiac tamponade. A few days later she presented with dyspnoea and hypotension. An echo-Doppler study was performed and an acquired post-traumatic ventricular septal defect (VSD) with left-to-right shunt was diagnosed. The patient was transferred to theatre where the defect was successfully repaired. Post-traumatic VSD is a rare complication of penetrating heart injuries and has a tendency to present late. Follow up of such cases is recommended with repeat echocardiography.