Impaired exercise hemodynamic responses in patients with HFpEF without a sympathetic vasoconstrictor reserve

Abstract

Impaired exercise hyperemia and blunted vasoconstrictor responsiveness have been reported in patients with heart failure with preserved ejection fraction (HFpEF). However, there is considerable heterogeneity in the degree to which vasodilatory capacity and sympathetic vasoconstrictor reserve are diminished. Given the integration of both vasodilation and vasoconstriction to appropriately regulate blood flow during exercise, we hypothesized that patients with HFpEF who are unable to vasoconstrict to sympatho-excitation (i.e., a cold pressor test; CPT; non-constrictors) have blunted leg blood flow (LBF) responses to single leg knee extensor (SLKE) exercise compared to patients with HFpEF who are able to vasoconstrict in response to sympatho-excitation (constrictors). Forty-three patients diagnosed with HFpEF underwent a CPT and performed submaximal and peak SLKE exercise while heart rate, blood pressure and common femoral artery blood flow were measured. The percent change in leg vascular conductance (LVC) during the CPT was used to categorize participants as non-constrictors (+26 ± 24%Δ LVC; n = 22, 16 female) or constrictors (−15 ± 14%Δ LVC; n = 21, 13 female). During submaximal SLKE exercise (7.5 watts) non-constrictors had a smaller increase in LBF (non-constrictors: Δ 1139 ± 425 ml/min; constrictors: Δ 1497 ± 454 ml/min; P = 0.011) and LVC (non-constrictors: Δ 9.8 ± 3.4 ml/min/mmHg; constrictors: Δ 13.3 ± 4.5 ml/min/mmHg; P = 0.007). LBF at peak SLKE exercise was also less in non-constrictors compared to constrictors (P = 0.033). In summary, patients with HFpEF without a sympathetic vasoconstrictor reserve present with impaired hemodynamic responses to exercise.