Impact of chronic cyanosis and reoxygenation on the microheterogeneity of the myocardial blood flow: Digital radiographic study in neonatal rats

Tomoko Tomii, Osami Honjo, Takeshi Matsumoto, Hiroyuki Tachibana, Yasuhiro Fujii, Kozo Ishino, Yasuo Ogasawara, Shunji Sano

Research output: Contribution to journalArticle

Abstract

Purpose: This study sought to show the heterogeneity of myocardial blood flow in the chronically hypoxic infantile myocardium and its response to reoxygenation using a novel type of digital radiography. Methods: Newborn rats were housed in a hypoxic chamber or in a normal chamber (controls). After 4 or 8 weeks, the control rats were ventilated with normoxic conditions, and the rats housed under hypoxia were ventilated with either hypoxic (cyanotic group) or normoxic conditions (reoxygenation group). Desmethylimipramine labeled with tritium (HDMI) was injected into the left ventricle, and both ventricular free walls were sectioned and sliced from the subepicardium to the subendocardium at 10 mm thickness. The within-layer distribution of HDMI density was measured by digital radiography, and its spatial heterogeneity (i.e., flow heterogeneity) was quantified by the coefficient of variation (CV) of flows. Results: There were no differences in the CV between the groups in either ventricle at 4 weeks of age and no differences in the right ventricle at 8 weeks of age. There was a trend toward a higher left ventricular CV in the cyanotic group than in the control group at 8 weeks of age (0.637 ± 0.099 vs. 0.510 ± 0.060, P = 0.06). At 8 weeks of age, the CV was lower in both ventricles in the reoxygenation group than in those of the control and cyanotic groups. Conclusion: The chronically hypoxic infantile myocardium exhibits regional flow heterogeneity similar to that observed in the normal myocardium in both ventricles and exhibits reduced flow heterogeneity in response to reoxygenation.

Original languageEnglish
Pages (from-to)672-680
Number of pages9
JournalGeneral Thoracic and Cardiovascular Surgery
Volume59
Issue number10
DOIs
Publication statusPublished - Oct 2011

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Cyanosis
Radiographic Image Enhancement
Myocardium
Heart Ventricles
Control Groups
Desipramine
Tritium

Keywords

  • Cyanotic heart
  • Digital radiography
  • Microheterogeneity
  • Myocardial blood flow

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Surgery
  • Pulmonary and Respiratory Medicine

Cite this

Impact of chronic cyanosis and reoxygenation on the microheterogeneity of the myocardial blood flow : Digital radiographic study in neonatal rats. / Tomii, Tomoko; Honjo, Osami; Matsumoto, Takeshi; Tachibana, Hiroyuki; Fujii, Yasuhiro; Ishino, Kozo; Ogasawara, Yasuo; Sano, Shunji.

In: General Thoracic and Cardiovascular Surgery, Vol. 59, No. 10, 10.2011, p. 672-680.

Research output: Contribution to journalArticle

Tomii, Tomoko ; Honjo, Osami ; Matsumoto, Takeshi ; Tachibana, Hiroyuki ; Fujii, Yasuhiro ; Ishino, Kozo ; Ogasawara, Yasuo ; Sano, Shunji. / Impact of chronic cyanosis and reoxygenation on the microheterogeneity of the myocardial blood flow : Digital radiographic study in neonatal rats. In: General Thoracic and Cardiovascular Surgery. 2011 ; Vol. 59, No. 10. pp. 672-680.
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T2 - Digital radiographic study in neonatal rats

AU - Tomii, Tomoko

AU - Honjo, Osami

AU - Matsumoto, Takeshi

AU - Tachibana, Hiroyuki

AU - Fujii, Yasuhiro

AU - Ishino, Kozo

AU - Ogasawara, Yasuo

AU - Sano, Shunji

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N2 - Purpose: This study sought to show the heterogeneity of myocardial blood flow in the chronically hypoxic infantile myocardium and its response to reoxygenation using a novel type of digital radiography. Methods: Newborn rats were housed in a hypoxic chamber or in a normal chamber (controls). After 4 or 8 weeks, the control rats were ventilated with normoxic conditions, and the rats housed under hypoxia were ventilated with either hypoxic (cyanotic group) or normoxic conditions (reoxygenation group). Desmethylimipramine labeled with tritium (HDMI) was injected into the left ventricle, and both ventricular free walls were sectioned and sliced from the subepicardium to the subendocardium at 10 mm thickness. The within-layer distribution of HDMI density was measured by digital radiography, and its spatial heterogeneity (i.e., flow heterogeneity) was quantified by the coefficient of variation (CV) of flows. Results: There were no differences in the CV between the groups in either ventricle at 4 weeks of age and no differences in the right ventricle at 8 weeks of age. There was a trend toward a higher left ventricular CV in the cyanotic group than in the control group at 8 weeks of age (0.637 ± 0.099 vs. 0.510 ± 0.060, P = 0.06). At 8 weeks of age, the CV was lower in both ventricles in the reoxygenation group than in those of the control and cyanotic groups. Conclusion: The chronically hypoxic infantile myocardium exhibits regional flow heterogeneity similar to that observed in the normal myocardium in both ventricles and exhibits reduced flow heterogeneity in response to reoxygenation.

AB - Purpose: This study sought to show the heterogeneity of myocardial blood flow in the chronically hypoxic infantile myocardium and its response to reoxygenation using a novel type of digital radiography. Methods: Newborn rats were housed in a hypoxic chamber or in a normal chamber (controls). After 4 or 8 weeks, the control rats were ventilated with normoxic conditions, and the rats housed under hypoxia were ventilated with either hypoxic (cyanotic group) or normoxic conditions (reoxygenation group). Desmethylimipramine labeled with tritium (HDMI) was injected into the left ventricle, and both ventricular free walls were sectioned and sliced from the subepicardium to the subendocardium at 10 mm thickness. The within-layer distribution of HDMI density was measured by digital radiography, and its spatial heterogeneity (i.e., flow heterogeneity) was quantified by the coefficient of variation (CV) of flows. Results: There were no differences in the CV between the groups in either ventricle at 4 weeks of age and no differences in the right ventricle at 8 weeks of age. There was a trend toward a higher left ventricular CV in the cyanotic group than in the control group at 8 weeks of age (0.637 ± 0.099 vs. 0.510 ± 0.060, P = 0.06). At 8 weeks of age, the CV was lower in both ventricles in the reoxygenation group than in those of the control and cyanotic groups. Conclusion: The chronically hypoxic infantile myocardium exhibits regional flow heterogeneity similar to that observed in the normal myocardium in both ventricles and exhibits reduced flow heterogeneity in response to reoxygenation.

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KW - Microheterogeneity

KW - Myocardial blood flow

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