Coronary perfusate composition influences diastolic properties, myocardialwater content, and histologic characteristics of the rat left ventricle

Background. Recent studies found that edema, histology, and left ventricula r diastolic compliance exhibit quantitative relationships in rats. Edema du e to low osmolarity coronary perfusates increases myocardial water content and histologic edema score and decreases left ventricular filling. The pres ent study examined effects of perfusate osmolarity and chemical composition on rat hearts. Methods. Arrested American Cancer Institute (ACI) rat hearts (4 degrees C) were perfused with different cardioplegia solutions, including Plegisol (28 9 mOsm/L), dilute Plegisol (172 mOsm/L), Stanford solution (409 mOsm/L), an d University of Wisconsin solution (315 mOsm/L). Controls had blood perfusi on (310 mOsm/L). Postmortem left ventricular pressure-volume curves and myo cardial water content were measured. After glutaraldehyde or formalin fixat ion, dehydration, and paraffin embedding, edema was graded subjectively. Results. Myocardial water content reflected perfusate osmolarity, being low est in Stanford and University of Wisconsin solutions (p < 0.05 versus othe r groups) and highest in dilute Plegisol (p < 0.05). Left ventricular filli ng volumes were smallest in dilute Plegisol and Plegisol (p < 0.05). Osmola rity was not a major determinant of myocardial edema grade, which was highe st with University of Wisconsin solution and dilute Plegisol (p < 0.05 vers us other groups). Conclusions. Perfusate osmolarity determined myocardial water content and l eft ventricular filling volume. However, perfusate chemical composition inf luenced the histologic appearance of edema. Pathologic grading of edema can be influenced by factors other than osmolarity alone. (Ann Thorac Surg 199 9;68:925-30) (C) 1999 by The Society of Thoracic Surgeons.