A 59-year-old man with hypertension and Crohn's disease that was complicated by fistulas was found unconscious at home. He was being treated with infliximab administered through a central venous access device, which had been placed for long-term intermittent treatment. The patient had been treated unsuccessfully with sulfasalazine, glucocorticoids, and immunomodulatory therapies, including methotrexate, azathioprine, and mercaptopurine. He was intubated and brought to the emergency department. Vital signs were stable, and the physical examination was notable for cyanosis of the head, neck, upper torso, and arms Credits to: Bharat Kumar, M.D. Nael Aboul Hosn, D.O. University of Kentucky, Lexington, KY
Superior vena cava syndrome, can please explain to me how it happened in thus case ?