Nat. Rev. Cardiol. doi:10.1038/nrcardio.2016.133 Figure 4 Four types of ulnopalmar arch patency based on the use of plethysmography and oximetry Figure 4 | Four types of ulnopalmar arch patency based on the use of plethysmography and oximetry. Type D indicates lack of sufficient dual circulation to the hand. Reprinted from Barbeau, G. R.et al. Evaluation of the ulnopalmar arterial arches with pulse oximetry and plethysmography: comparison with the Allen's text in 1010 patients. Am. Heart J. 147 (3), 489–493 © (2004), with permission from Elsevier. Reprinted from Barbeau, G. R. et al. Evaluation of the ulnopalmar arterial arches with pulse oximetry and plethysmography: comparison with the Allen’s text in 1010 patients. Am. Heart J. 147 (3), 489–493 © (2004), with permission from Elsevier. Rao, S. V. & Stone, G. W. (2016) Arterial access and arteriotomy site closure devices Nat. Rev. Cardiol. doi:10.1038/nrcardio.2016.133