Plasma clearance of polyfructosan and extracellular body fluid distribution in idiopathic dilated cardiomyopathy and after heart transplantation

The total extracellular fluid volume and distribution in plasma and interstitial spaces, and the microvascular permeability properties were studied in 16 nonedematous patients with congestive heart failure (CHF) due to idiopathic dilated cardiomyopathy and 17 such patients who underwent heart transplantation (HT) by analyzing the 3-hour plasma disappearance curve of polyfructosan. Eighteen healthy subjects served as controls. Polyfructosan (3.5 kD) is an extracellular marker and inulin analog transported almost solely by diffusion. The initial capillary membrane plasma clearance (i.e., the permeability-surface area product), the interstitial plasma clearance determined at 10 minutes (clearance[10]), and the extracellular volume were determined from the polyfructosan curves. I-131-albumin was used as a plasma volume reference. Permeability-surface area product was elevated in both patient groups (6.6 ± 1.9 ml/ kg/min in the CHF group and 6.7 ± 2.0 ml/kg/min in the HT group vs 5.1 ± 1.3 ml/kg/min in controls, p <0.01 for both), whereas clearance(10) was normalized in the HT group (4.5 ± 0.9 ml/kg/min in the HT group, 4.4 ± 0.7 ml/kg/min in controls vs 5.0 ± 0.9 ml/kg/min in the CHF group, p <0.1 and p <0.05, respectively). The normalization of interstitial plasma clearance of polyfructosan was associated with time since HT (r = 0.49, p <0.05). Plasma volumes were similar in all 3 groups (41 ± 8 ml/kg in controls, 44 ± 13 in the CHF group and 39 ± 8 in the HT group). In contrast, total extracellular volume was elevated in both patients groups (177 ± 27 ml/kg in the CHF group and 173 ± 27 in the HT group vs 152 ± 12 in controls, p <0.01). The results strongly suggest a microvascular permeability defect in both patient groups that perhaps plays a role in the extravascular distribution of the excess extracellular fluid volume.