Abstract
After banding the main pulmonary trunk at ±0.45 gestation, nine fetal lambs were studied subsequently at ±0.85 gestation (133±1.4 d). Eleven fetal lambs acted as controls (130±2.5 d). Right ventricular (RV) systolic hypertension (110±11 mmHg) was produced (systemic arterial systolic pressure 72±7 mmHg). After vital staining with horseradish peroxidase, radioautography with tritiated thymidine and fixation by coronary perfusion, RV and left ventricular (LV) free walls and interventricular septum (S) were weighed and subjected to stereologic point counting analysis with light microscopy. RV mass was greater than in the control group (10.4±.7 vs. 5.1±.4 g, p<0.001). This was due to hyperplasia as evidenced by smaller or unchanged myocyte diameter (6.2±.2 vs. 6.7±.13 μm NS). LV mass was also greater than control (7.6±.7 vs. 5.5±.5 g, p <0.05). This was less than the RV mass increase and was due to hypertrophy (myocyte diameter 6.0±.07 vs. 5.7±.01 μm, p<0.001). Increased myocyte mitosis was demonstrated by increased nuclear uptake of tritiated thymidine. S showed similar changes to LV. RV and LV capillaries were larger in diameter than control (RV 5.0±.01 vs. 4.1±.01 μm, p <0.001; LV 5.3±.08 vs. 4.3±.01 μm, p < .001) and fewer in number/unit area (RV 44±2.7 vs. 78±4.0; LV 51±3.9 vs. 74±4.6, p < .001). It is suggested that the different myocardial response of the ventricles is related to differences in stress of pressure loading on the right and volume loading on the left ventricle.
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Crone, R., Kleinman, C., Heymann, M. et al. 93 MORPHOLOGIC RESPONSES OF THE FETAL MYOCARDIUM TO PULMONARY ARTERY BANDING IN UTERO. Pediatr Res 12 (Suppl 4), 379 (1978). https://doi.org/10.1203/00006450-197804001-00098
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DOI: https://doi.org/10.1203/00006450-197804001-00098