1 Department of Diagnostic and Interventional Radiology, St. James's University Hospital, Beckett Street, Leeds LS9 7TF, United Kingdom. Electronic address: t.shiwani@nhs.net.
2 Department of Anaesthesia, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom.
3 Department of Cardiology, Jubilee Wing, Leeds General Infirmary, Leeds, United Kingdom.
4 Department of Diagnostic and Interventional Radiology, St. James's University Hospital, Beckett Street, Leeds LS9 7TF, United Kingdom.