Tachycardia after acute deceleration injury

A 29-year-old man crashed at high speed into another vehicle at traffic lights. He was able to get out of his van but then collapsed after running a few metres. On arrival in the emergency department he was conscious, with a pulse of 140 beats/min and blood pressure of 110/32 mm Hg. He had collapsing arterial pulses and an early diastolic murmur. He had a chest radiograph (figure 1A) and a skeletal survey which demonstrated multiple fractures, involving his left hand, right femur, right calcaneus, and left first and second ribs. A CT scan of the thorax was performed with a radiological contrast agent but without gated images because of the tachycardia (Figure 1B). The blood pressure and pulse were attributed to blood loss into the right thigh. Urgent cardiology review and bedside echocardiography were requested before he had emergency orthopaedic surgery (figure 1C, D) (online supplementary video 1).DC1SP110.1136/heartjnl-2018-314082.supp1Supplementary file 1heartjnl;105/5/398/F1F1F1Figure 1(A-D) Chest radiograph, CT thorax with contrast, parasternal long-axis transthoracic view (grey scale) and with colour flow. The arrow in section C highlights the area of significance (mobile linear structure). QUESTION: What is the most likely diagnosis?Traumatic dissection of the aortic root.Subaortic membrane or diaphragm.Traumatic transection of the aorta.Traumatic rupture of the aortic valve.Myocardial rupture.