Heterogeneity of Myocardial Edema in Isolated Pig Hearts after Perfusion with Different Types of Cardioprotective Solutions

Abstract

The extent and distribution of myocardial edema induced by perfusion with cardioprotective Solutions is of great interest. Domestic pig hearts (n = 12) were perfused in situ after aortic cross clamping either with Bretschneider's cardioplegic Solution (HTK, 4°C, n = 3), with a heparinized Krebs-Henseleit Solution containing 30 mmol/L 2,3 Butanedionemonoxime (BDM, 4°C, n = 3) or with heparinized pig blood (HPB, 24°C, n = 3). After a three-hours storage period, magnetic resonance tomography (MRI) was carried out. The acquired T1 -weighted data were used for the subsequent three-dimensional reconstruction based on the “Heidelberg ray-tracing technique”. Then small myocardial tissue blocks (n = 216) were excised from these hearts for dry weight measurements for 9 preselected regions in duplicate including ventricular papillary muscle, ventricular free wall, ventricular septum, apex, and atrial tissue. In control hearts (n = 3), dry weight was measured immediately after explantation (no MRI). The results of dry-weight measurements and three dimensional visualization were compared. Dry-weight measurements revealed that considerable myocardial edema is induced by any of the experimental procedures. The effects were most pronounced after BDM perfusion. Regardless how the edema was induced, there were significant differences of the water content within the heart: the water content in the heads of the papillary muscles and in the interventricular septum was always smaller than that of the free left- and right-ventricular walls. The heterogeneity of myocardial edema and its spatial distribution pattern could be qualitatively visualized. The experimental data (biophysical data and 3D visualization) clearly show a heterogeneity of myocardial edema induced by different types of cardioprotective Solutions. As the presence of myocardial edema represents one of the crucial events in the pathophysiology of myocardial dysfunction occurring during myocardial infarction, ischemia, heart transplantation, and extracorporeal circulation, the present study represents an interesting contribution towards intravital detection and distribution of myocardial edema.

Key words

Myocardial edema - Dry weight - Cardioprotection - Ray-Tracing - Visualization