Regional Variation in Myocardial Water Content in the Edematous Pig Heart

Abstract

Background. The purpose of this study was to examine regional variation in myocardial water content (%MWC) throughout the iatrogenically edematous pig heart.Methods. Edema was induced by hemodilution in domestic swine (n = 26). Hearts were arrested with potassium chloride. The left ventricular free wall (LVFW), interventricular septum (IVS), and right ventricular free wall (RVFW) were biopsied at the apex, base, and equator. Full-thickness biopsy (Full, 0.5–1 g) and subendocardial (Endo, 0.1–0.2 g) biopsies were removed from each region. %MWC was determined for each biopsy.Results. The %MWC for all hearts were as follows: Endo, 81.1 ± 0.1, and Full, 80.6 ± 0.1* (*P < 0.02); apex, 81.1 ± 0.2*, equator, 80.7 ± 0.2, and base, 80.4 ± 0.2 (*P < 0.02); RVFW, 81.4 ± 0.3*, IVS, 80.8 ± 0.2*, and LVFW, 80.3 ± 0.1* (*P < 0.02). For 18 hearts with LV samples with average %MWC ≥ 80%, the percentages were apex, 81.4 ± 0.2*, equator, 81.0 ± 0.2*, and base, 80.6 ± 0.2* (*P < 0.02) (repeated measures, ANOVA).Conclusion. In the iatrogenically edematous porcine heart, a significant water gradient exists, with Endo > Full, apex > equator > base, and RVFW > IVS > LVFW. These results indicate that when examining edema, consistent biopsy results depend on a reproducible sampling site. Water content tends to be highest in thin-walled portions of the heart, suggesting that contractile force may be important in the distribution of edema.