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EPR oximetry in the beating heart: Myocardial oxygen consumption rate as an index of postischemic recovery
Author(s) -
Ilangovan Govindasamy,
Liebgott Thibaut,
Kutala Vijay Kumar,
Petryakov Sergey,
Zweier Jay L.,
Kuppusamy Periannan
Publication year - 2004
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20000
Subject(s) - oxygen , oxygenation , cardiology , perfusion , heart rate , medicine , ischemia , hemodynamics , chemistry , anesthesia , organic chemistry , blood pressure
Oxygen plays a critical role in the pathophysiology of myocardial injury during both ischemia and subsequent reperfusion (I/R). Thus, oxygen concentration is an important variable to measure during I/R. In the present work, electron paramagnetic resonance (EPR)‐based oximetry was used to measure the oxygen concentration during a series of I/R episodes and oxygenation levels were correlated with the contractile and hemodynamic functions of the heart. A custom‐developed electronically tunable surface coil resonator working at 1.1 GHz was used to determine tissue pO 2 in the beating heart. Microcrystalline particulate of lithium phthalocyanine was used as an EPR oximetry probe. Isolated and perfused rat hearts were subjected to 1 or 3 hr durations of preischemic perfusion, followed by 15‐min I/R cycles. In hearts perfused for 3 hr prior to 15‐min I/R cycles, the myocardial pO 2 decreased gradually on subsequent reperfusions of three successive I/R cycles. However, in hearts perfused for 1 hr there was almost 100% recovery of myocardial pO 2 in all three I/R cycles. The extent of oxygenation recovered in each reperfusion cycle correlated with the recovery of hemodynamic and contractile function. The results also showed that the oxygen consumption rate of the heart at the end of each I/R episode decreased in direct proportion to the functional recovery. In summary, it was observed that the amount of myocardial oxygen consumption during I/R could provide a reliable index of functional impairment in the heart. Magn Reson Med 51:835–842, 2004. © 2004 Wiley‐Liss, Inc.