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Simultaneous delivery of cardioplegic solution through a single coronary artery and the coronary sinus
INVOLVEMENT OF THE NITRIC OXIDE PATHWAY IN THE ANOXIC- REOXYGENATED DEVELOPING HEART Courgeault-Gautieti, l6r6me Terrand’, Francoise Emanuela Felley-Bosco*, - Anne-Catherine Rochat’, and Eric Raddatz’. Institute of Pave1 Kucera’ Physiology’, and Institute of Pharmacology and Toxicolog$, University of Lausanne, Switzerland. The effects of endogenous nitric oxide (NO) during mvocardial ischemia-reperfusion are rather controversial sp&ally in the imma&e lieart. Spontaneously beating hearts isolated from 4-dav-old chick embrvos were either homogenized for b&her&al deter&nations or submitted to 30 min anoxia/lOO min reoxygenation (A/R). The chrono-, dromo- and inotropic responses to A/R were recorded continuously. Hearts were treated with NO synthase (NOS) inhibitors (L-NMMA 5mh4 or L-MO 5mh4) or with NOS substrate (L-arginine lOmh4). Inducible NOS (iNOS) protein was detectable by immunoblotting and its basal activity, assessed by production of labelled citrulline, was 14~~1 pmoLmiri’mg protein-‘. L-N10 decreased this activity by 60% (p
SIMULTANEOUS DELIVERY SOLUTION THROUGH A ARTERY AND THE CORONARY
OF CARDIOPLEGIC SINGLE CORONARY SINUS
Ganghong Tian, Bo Xiang, Guaugping Dai, Shelley Germscheid, Rachelle Mariash, William Lindsay, Roxanne Deslauriers. Institute for Biodiagnostics, Winnipeg, MB, Canada. This study was to determine whether simultaneous delivery of cardioplegia (SC) through a single coronary artery and the coronary sinus provides homogeneous perfusion. SC was conducted in seven isolated pig hearts using the coronary sinus in conjunction with the LAD, LCX, and the right coronary artery (RCA), respectively. Injection of a magnetic resonance contrast agent during SC into a perfusing-artery resulted in increased Tl image intensity not only in the territory of the perfusing-artery but also in the areas normally served by the other two venting arteries. With contrast agent given into the coronary sinus during SC, myocardium in the territories of the two venting-arteries was enhanced while myocardium in the perfusing-artery territory and right ventricular wall remained dark. Moreover, a significant amount of effluent was collected from the venting-arteries during SC: 4.7-7.8 ml/min from the RCA, 10.5-17,7 ml/min from the LAD, and 9.7- 15.2 mVmin from the LCX. The results demonstrate that SC through a single coronary artery and the coronary sinus provides homogeneous perfusion to the entire heart. During SC, arterial flow supports its own designated myocardium as well as adjacent myocardium normally served by the venting arteries. Venous perfusion of SC mainly supports myocardium in the territories of the venting arteries and it does not perfuse the right ventricular free wall. A122
A FLOW-INDEPENDENT FOR ASSESSING INFARCT
MR IMAGING MYOCARDIUM
METHOD
Ganghong Tian, Guangping Dai, Bo Xiang, Jiankang Sun, Lori Gregorash, Allan Turner, Shelley Germscheid, Roxanne Deslauriers. Institute for Biodiagnostics, National Research Council, Winnipeg, Manitoba, Canada This study was to determine whether the efficacy of our interleaved Tl-T2* imaging technique for assessment of myocardial injury was affected by coronary blood flow. Six isolated pig hearta were subjected to a 2 hrs of occlusion of the LAD and 1 hr of reperfusion. The hearts were then placed into a 7 Tesla magnet. An MR contrast agent (Gd-DTPA, 2 ml) was injected as a bolus into the aorta at a total coronary flow of 150 ml/min and 300 ml/min, respectively. Contrast-induced Tl and T2* signal changes during the bolus injection were registered using the interleaved Tl-T2* imaging. At a coronary flow of 150 ml/min, the percentage of T2* recovery at maximum Tl signal intensity differed significantly among the normal (35 + 3%), peripheral infarct (76 + 3.4%), and infarct core areas of the myocardium (93 + 6%). With a coronary flow of 300 ml/min, the three regions of the myocardium also showed a significant difference in percentage of T2* recovery (32 + 3% in the normal region, 73 + 1% in the peripheral infarct, and 91 + 2% in the infarct core). More importantly, the percentages of T2* recovery in any given region obtained at the two different coronary flows were comparable. The results demonstrate that the interleaved Tl-T2* imaging with a bolus injection of contrast agent is a flow-independent technique that can reliably assess myocardial viability.
MAPPING CONTRAST
INFARCTED ENHANCED
MYOCARDIUM MR IMAGING
USING
Ganghong Tian, Gimngping Dai, Bo Xiang, Rachelle Mariash, Lori Gregorash, Allan Turner, Roxanne Deslauriers. Institute for Biodiagnostics, NRC, Winnipeg, Manitoba, Canada It has been suggested that reduction in blood flow in infarcted myocardium can reduce the usefulness of Tl imaging for assessment’ of myocardial injury. This study determined whether infarcted myocardium can be delineated using a map of T2* signal recovery percentage in a flow-independent manner. Myocardial infarct of pig heart was created by a 2-hr occlusion of the LAD and 1-hr reperfusion (n=8). Gd-DTPA (2 ml) was injected into the aorta as a bolus and its first passage was monitored using an interleaved Tl-T2* imaging. It was found that contrast-induced Tl shortening was comparable between the infarct core (1136 +_ 99 ms) and normal myocardium (1155 f 55 ms). The similar Tl shortening in both regions may be related to a significant reduction in blood flow in the infarct core areas (0.12 * 0.19 ml/min/g) relative to normal myocardium (4.55 + 0.48 ml/min/g). However, Tl-T2* images showed that the percentage of T2* signal recovery at maximum Tl signal was significantly greater in the infarct core (90 f 2.8%) than in normal myocardium (30 + 2.4%). We hypothesize that the greater percentage of TZ* signal recovery in the infarct core was due to the disruption of cell membranes. Moreover, maps of the percentage of T2* recovery perfectly match TTC staining pictures, which clearly show infarcted myocardium. This demonstrates that use of Tl imaging alone cannot reliably assess myocardial injury and that maps of the percentage of T2* recovery clearly delineate myocardial infarct.
SIMULTANEOUS DELIVERY SOLUTION THROUGH A ARTERY AND THE CORONARY
OF CARDIOPLEGIC SINGLE CORONARY SINUS
Ganghong Tian, Bo Xiang, Guaugping Dai, Shelley Germscheid, Rachelle Mariash, William Lindsay, Roxanne Deslauriers. Institute for Biodiagnostics, Winnipeg, MB, Canada. This study was to determine whether simultaneous delivery of cardioplegia (SC) through a single coronary artery and the coronary sinus provides homogeneous perfusion. SC was conducted in seven isolated pig hearts using the coronary sinus in conjunction with the LAD, LCX, and the right coronary artery (RCA), respectively. Injection of a magnetic resonance contrast agent during SC into a perfusing-artery resulted in increased Tl image intensity not only in the territory of the perfusing-artery but also in the areas normally served by the other two venting arteries. With contrast agent given into the coronary sinus during SC, myocardium in the territories of the two venting-arteries was enhanced while myocardium in the perfusing-artery territory and right ventricular wall remained dark. Moreover, a significant amount of effluent was collected from the venting-arteries during SC: 4.7-7.8 ml/min from the RCA, 10.5-17,7 ml/min from the LAD, and 9.7- 15.2 mVmin from the LCX. The results demonstrate that SC through a single coronary artery and the coronary sinus provides homogeneous perfusion to the entire heart. During SC, arterial flow supports its own designated myocardium as well as adjacent myocardium normally served by the venting arteries. Venous perfusion of SC mainly supports myocardium in the territories of the venting arteries and it does not perfuse the right ventricular free wall. A122
A FLOW-INDEPENDENT FOR ASSESSING INFARCT
MR IMAGING MYOCARDIUM
METHOD
Ganghong Tian, Guangping Dai, Bo Xiang, Jiankang Sun, Lori Gregorash, Allan Turner, Shelley Germscheid, Roxanne Deslauriers. Institute for Biodiagnostics, National Research Council, Winnipeg, Manitoba, Canada This study was to determine whether the efficacy of our interleaved Tl-T2* imaging technique for assessment of myocardial injury was affected by coronary blood flow. Six isolated pig hearta were subjected to a 2 hrs of occlusion of the LAD and 1 hr of reperfusion. The hearts were then placed into a 7 Tesla magnet. An MR contrast agent (Gd-DTPA, 2 ml) was injected as a bolus into the aorta at a total coronary flow of 150 ml/min and 300 ml/min, respectively. Contrast-induced Tl and T2* signal changes during the bolus injection were registered using the interleaved Tl-T2* imaging. At a coronary flow of 150 ml/min, the percentage of T2* recovery at maximum Tl signal intensity differed significantly among the normal (35 + 3%), peripheral infarct (76 + 3.4%), and infarct core areas of the myocardium (93 + 6%). With a coronary flow of 300 ml/min, the three regions of the myocardium also showed a significant difference in percentage of T2* recovery (32 + 3% in the normal region, 73 + 1% in the peripheral infarct, and 91 + 2% in the infarct core). More importantly, the percentages of T2* recovery in any given region obtained at the two different coronary flows were comparable. The results demonstrate that the interleaved Tl-T2* imaging with a bolus injection of contrast agent is a flow-independent technique that can reliably assess myocardial viability.
MAPPING CONTRAST
INFARCTED ENHANCED
MYOCARDIUM MR IMAGING
USING
Ganghong Tian, Gimngping Dai, Bo Xiang, Rachelle Mariash, Lori Gregorash, Allan Turner, Roxanne Deslauriers. Institute for Biodiagnostics, NRC, Winnipeg, Manitoba, Canada It has been suggested that reduction in blood flow in infarcted myocardium can reduce the usefulness of Tl imaging for assessment’ of myocardial injury. This study determined whether infarcted myocardium can be delineated using a map of T2* signal recovery percentage in a flow-independent manner. Myocardial infarct of pig heart was created by a 2-hr occlusion of the LAD and 1-hr reperfusion (n=8). Gd-DTPA (2 ml) was injected into the aorta as a bolus and its first passage was monitored using an interleaved Tl-T2* imaging. It was found that contrast-induced Tl shortening was comparable between the infarct core (1136 +_ 99 ms) and normal myocardium (1155 f 55 ms). The similar Tl shortening in both regions may be related to a significant reduction in blood flow in the infarct core areas (0.12 * 0.19 ml/min/g) relative to normal myocardium (4.55 + 0.48 ml/min/g). However, Tl-T2* images showed that the percentage of T2* signal recovery at maximum Tl signal was significantly greater in the infarct core (90 f 2.8%) than in normal myocardium (30 + 2.4%). We hypothesize that the greater percentage of TZ* signal recovery in the infarct core was due to the disruption of cell membranes. Moreover, maps of the percentage of T2* recovery perfectly match TTC staining pictures, which clearly show infarcted myocardium. This demonstrates that use of Tl imaging alone cannot reliably assess myocardial injury and that maps of the percentage of T2* recovery clearly delineate myocardial infarct.