Exercise blood flow and microvascular distensibility in skeletal muscle normalize after heart transplantation

Abstract

This study investigated the effect of heart transplantation (HTX) on reduced exercise blood flow and microvascular stiffness in patients with congestive heart failure (CHF). Skeletal muscle blood flow (SMBF) during graded maximal supine bicycle exercise and microvascular distensibility (i.e., stiffness) were measured in musculus tibialis anterior by the isotope washout method. Measurements were performed in a cross-sectional study with 31 CHF patients and 28 patients, mean 9 months after HTX, and in a longitudinal study in 12 CHF patients before, 3 months, and 14 months after HTX, and in 31 healthy controls. Maximal SMBF: In the cross-sectional study, maximal SMBF was reduced in severe CHF patients (3.6 +/- 2.5 mL (100 g min)(-1)) and increased after HTX (7.7 +/- 4.8; p < 0.01 versus controls (11 +/- 4.1). Maximal SMBF was reduced in CHF patients (5.8 +/- 4.0) and reversed to normalization 3 months after HTX (10.3 +/- 4.4) in the longitudinal study. Microvascular distensibility: The distensibility was reduced (severe CHF, 12 +/- 8%; moderate CHF, 23 +/- 14%) in the cross-sectional study and increased after HTX towards normalization (38 +/-20%; controls: 44 +/- 17). In the longitudinal study, distensibility in CHF patients (14 +/- 6%) increased gradually to 32 +/- 12% (p < 0.005) at 3 months and normalized 14 months after HTX (46 +/- 17%). HTX gradually reversed the reduced SMBF and microvascular distensibility in CHF patients towards normalization.