Use of diffusion tensor imaging to predict myocardial viability after warm global ischemia: possible avenue for use of non-beating donor hearts.
BACKGROUND
The assessment of myocardial viability after global warm ischemia (WI) but before reperfusion is challenging. We hypothesized that fractional anisotropy (FA), a magnetic resonance imaging (MRI) parameter of water diffusion that characterizes cellular integrity within tissues, provides a rapid and useful method for evaluating the viability of hearts after WI.


METHODS
Dog hearts were exposed to 60 minutes of WI after exanguination, explanted and preserved in a cold, non-beating state for 6 hours, using continuous perfusion (CP) or static cold storage (CS). Toward the end of preservation, a global FA assessment, acquired using MRI, was compared with analyses obtained from myocardial biopsies that included adenosine triphosphate (ATP), endothelin-1 (ET-1) and caspase-3 levels, light microscopy and tetrazolium staining. Functional recovery was analyzed after restoration of blood flow on a non-working Langendorff preparation.


RESULTS
FA measured at the end of CP showed strong correlations with all parameters of functional recovery (developed pressure, R = 0.60; dP/dt, R = 0.96; -dP/dt, R = 0.96). Although FA also correlated with tissue levels of ATP, ET-1 and caspase-3 (R = 0.77, -0.84, -0.64), recovery of myocardial function did not correlate with these markers or any other conventional analyses of myocardial injury (troponin I, changes on light microscopy or tetrazolium staining).


CONCLUSIONS
FA, an MRI-based parameter that indicates cellular integrity, was found to reflect better myocardial ATP stores, less induction of ET-1 and caspase-3 and improved functional recovery of hearts after global WI. As a clinically applicable tool capable of rapidly differentiating reversible from lethal injury, diffusion tensor imaging may prove useful in the eventual adoption of non-beating donor hearts for transplantation.
Collins
Michael J
MJ
Division of Cardiac Surgery, Department of Surgery, University of Maryland Medical System, Baltimore, Maryland 21201, USA.
Ozeki
Toshinaga
T
Zhuo
Jiachen
J
Gu
Junyan
J
Gullapalli
Rao
R
Pierson
Richard N
RN
Griffith
Bartley P
BP
Fedak
Paul W M
PW
Poston
Robert S
RS
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016880:Anisotropy; D015415:Biomarkers / Q000378:metabolism; D001706:Biopsy; D053148:Caspase 3 / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging; D004285:Dogs; D019332:Endothelin-1 / Q000378:metabolism; D006321:Heart / Q000503:physiopathology*; D006323:Heart Arrest / Q000503:physiopathology*; D009206:Myocardium / Q000201:enzymology / Q000473:pathology; D009926:Organ Preservation; D011237:Predictive Value of Tests; D020127:Recovery of Function; D014019:Tissue Donors; D014022:Tissue Survival; D052096:Warm Ischemia
D015415:Biomarkers; D019332:Endothelin-1; D000255:Adenosine Triphosphate; D053148:Caspase 3