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Topographic changes in the left ventricle after experimentally induced myocardial infarction in the rat.
Am J Cardiol. 1983 Mar 01; 51(5):872-6.AJ

Abstract

The factors that determine the thickness of transmural myocardial infarcts are unknown. Therefore, the relation between the size and thickness of transmural infarcts in 67 rats 21 days after occlusion of the left main coronary artery was studied. On examination of histologic sections, infarct size was determined by planimetry and expressed as a percentage of the left ventricular (LV) area, and thickness was expressed as a percentage of noninfarcted ventricular septal wall thickness. The circumferential length of the infarcted ventricle was measured in millimeters, as well as the circumferential length of the noninfarcted ventricular septum. Septal wall thickness was similar in rats with transmural infarcts and in sham-operated rats. No significant correlation was observed between infarct size and thickness (r = 0.10) or between circumferential length of the infarct and infarct thickness (r = 0.17). However, large (greater than or equal to 20% of the left ventricle, n = 37) and small (less than 20% of the left ventricle, n = 30) infarcts which were similarly thin (37 +/- 1% and 34 +/- 2% of septal wall thickness, respectively) affected LV topography differently. Large infarcts resulted in a 23% greater loss of myocardium (p less than 0.001), greater expansion of the LV cavity (18 +/- 9 mm2 compared with 14 +/- 1 mm2 in small infarcts, p less than 0.005), and lengthening of the septal wall (7.2 +/- 1.1 mm and 6.7 +/- 1.0 mm in large and small infarcts, respectively [p less than 0.05], and 6.3 +/- 0.1 mm in shams). Increase in cavity area and septal length in infarcted ventricles suggested a volume overload hypertrophy, which at 3 weeks was nonetheless inadequate to provide as much normal muscle as was present in sham-operated rats. In an additional 9 rats with subendocardial infarctions (involving less than 75% of the LV wall from endocardium to epicardium), the LV walls were thicker (94 +/- 5% of septal wall thickness, compared with 35 +/- 1% for transmural infarcts, p less than 0.001) and an inverse correlation was observed between infarct size and thickness. In conclusion, neither the size of a transmural infarct in rat nor the circumferential length of infarction determines the thickness of the infarct; however, infarct size does affect LV topography by increasing LV cavity area and the length of the noninfarcted septal wall. Subendocardial infarcts result in less myocardial thinning than do transmural infarcts.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

6829445

Citation

Roberts, C S., et al. "Topographic Changes in the Left Ventricle After Experimentally Induced Myocardial Infarction in the Rat." The American Journal of Cardiology, vol. 51, no. 5, 1983, pp. 872-6.
Roberts CS, Maclean D, Braunwald E, et al. Topographic changes in the left ventricle after experimentally induced myocardial infarction in the rat. Am J Cardiol. 1983;51(5):872-6.
Roberts, C. S., Maclean, D., Braunwald, E., Maroko, P. R., & Kloner, R. A. (1983). Topographic changes in the left ventricle after experimentally induced myocardial infarction in the rat. The American Journal of Cardiology, 51(5), 872-6.
Roberts CS, et al. Topographic Changes in the Left Ventricle After Experimentally Induced Myocardial Infarction in the Rat. Am J Cardiol. 1983 Mar 1;51(5):872-6. PubMed PMID: 6829445.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Topographic changes in the left ventricle after experimentally induced myocardial infarction in the rat. AU - Roberts,C S, AU - Maclean,D, AU - Braunwald,E, AU - Maroko,P R, AU - Kloner,R A, PY - 1983/3/1/pubmed PY - 1983/3/1/medline PY - 1983/3/1/entrez SP - 872 EP - 6 JF - The American journal of cardiology JO - Am J Cardiol VL - 51 IS - 5 N2 - The factors that determine the thickness of transmural myocardial infarcts are unknown. Therefore, the relation between the size and thickness of transmural infarcts in 67 rats 21 days after occlusion of the left main coronary artery was studied. On examination of histologic sections, infarct size was determined by planimetry and expressed as a percentage of the left ventricular (LV) area, and thickness was expressed as a percentage of noninfarcted ventricular septal wall thickness. The circumferential length of the infarcted ventricle was measured in millimeters, as well as the circumferential length of the noninfarcted ventricular septum. Septal wall thickness was similar in rats with transmural infarcts and in sham-operated rats. No significant correlation was observed between infarct size and thickness (r = 0.10) or between circumferential length of the infarct and infarct thickness (r = 0.17). However, large (greater than or equal to 20% of the left ventricle, n = 37) and small (less than 20% of the left ventricle, n = 30) infarcts which were similarly thin (37 +/- 1% and 34 +/- 2% of septal wall thickness, respectively) affected LV topography differently. Large infarcts resulted in a 23% greater loss of myocardium (p less than 0.001), greater expansion of the LV cavity (18 +/- 9 mm2 compared with 14 +/- 1 mm2 in small infarcts, p less than 0.005), and lengthening of the septal wall (7.2 +/- 1.1 mm and 6.7 +/- 1.0 mm in large and small infarcts, respectively [p less than 0.05], and 6.3 +/- 0.1 mm in shams). Increase in cavity area and septal length in infarcted ventricles suggested a volume overload hypertrophy, which at 3 weeks was nonetheless inadequate to provide as much normal muscle as was present in sham-operated rats. In an additional 9 rats with subendocardial infarctions (involving less than 75% of the LV wall from endocardium to epicardium), the LV walls were thicker (94 +/- 5% of septal wall thickness, compared with 35 +/- 1% for transmural infarcts, p less than 0.001) and an inverse correlation was observed between infarct size and thickness. In conclusion, neither the size of a transmural infarct in rat nor the circumferential length of infarction determines the thickness of the infarct; however, infarct size does affect LV topography by increasing LV cavity area and the length of the noninfarcted septal wall. Subendocardial infarcts result in less myocardial thinning than do transmural infarcts. SN - 0002-9149 UR - https://www.unboundmedicine.com/medline/citation/6829445/Topographic_changes_in_the_left_ventricle_after_experimentally_induced_myocardial_infarction_in_the_rat_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0002-9149(83)80147-7 DB - PRIME DP - Unbound Medicine ER -