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Session: Imaging - Cardiac System
Session starts: Thursday 24 January, 13:30
Presentation starts: 14:15
Room: Lecture room 559

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Stefan Sandker (Thoraxcenter Twente, Medisch Spectrum Twente, Enschede)
Erwin Hondebrink (Department of Biomedical Photonic Imaging, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede)
Jan Grandjean (Thoraxcenter Twente, Medisch Spectrum Twente, Enschede)
Wiendelt Steenbergen (Department of Biomedical Photonic Imaging, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede)

Abstract:
Introduction The radial artery (RA) has become a routinely used conduit for coronary artery bypass graft surgery (CABG) [1]. Prior to surgery the Allen’s test is performed to test the patency of the ulnar artery (UA). Pressure is applied to the RA and UA and the patient is asked to make a fist. Pressure on the UA is released and the red color of the hand should return within 5 seconds, a negative Allen’s test [2]. If the test is positive, the RA should not be used as bypass graft. The predictive value of a positive test is 53% [3]. In this pilot study we investigated if laser speckle contrast analysis (LASCA) provides a more objective determination of the reperfusion time compared to the conventional Allen’s test. Methods When the hand is illuminated with coherent laser light, here a 660nm 75mW continuous wave laser, the backscattered light will result in constructive and destructive interference consisting of bright and dark areas, speckles [4]. This speckle pattern will change due to movement of red blood cells. LASCA uses these changes to visualize the perfusion during the Allen’s test at 30 frames/second. The average perfusion value of each frame of a 4x4cm area on the palmar side of the hand is calculated and set against time. The reperfusion time is the time to reach maximal perfusion after releasing pressure of the UA and is calculated using the first derivative of a 6th order polynomial curve fit. The calculated reperfusion time using LASCA is compared to the conventional Allen’s test of patients undergoing CABG (n=17) as performed by the nurse practitioner. Results LASCA measurements showed a negative Allen’s test of both hands of eleven patients. Six had a borderline reperfusion time of 5 – 5.5 seconds and/or a positive Allen’s test of one or both hands. These results were consistent with the conventional Allen’s test. Furthermore, differences in reperfusion of different parts in the measured area of the hand were visible. Conclusion LASCA is able to visualize reperfusion of the hand and measure a quick, moderate, slow reperfusion response or no reperfusion. It is technically feasible to determine the reperfusion time of the hand. In the future, LASCA could be a useful and objective tool to assess ulnar collateral blood supply to the hand prior to harvesting of the radial artery as a bypass graft. REFERENCES [1] Kobayashi J. Radial artery as a graft for coronary artery bypass grafting. Circ J 2009; 73: 1178-1183. [2] Cable DG, Mullany CJ, Schaff HV. The Allen test. Ann Thorac Surg 1999; 67: 876-877. [3] Asif M, Sarkar PK. Three-Digit Allen’s Test. Ann Thorac Surg 2007; 84: 686-687. [4] Draijer M, Hondebrink E, van Leeuwen T, Steenbergen W. Review of laser speckle contrast techniques for visualizing tissue perfusion. Lasers Med Sci 2009; 24: 639-651.