The effect of intravenous clonidine hydrochloride on the isolated forearm venous segment in heart failure

The effects of intravenous (IV) clonidine (150 micrograms) on the isolated forearm venous segment of ten patients with heart failure were studied. Clonidine reduced pressure in the isolated venous segment of all patients (12.8 +/- 2.1 to 10.6 +/- 1.4 mm Hg, p less than 0.005). In addition, IV clonidine decreased the pressor response to mental arithmetic (2.9 +/- 0.3 mm Hg to 1.8 +/- 0.3 mm Hg, p less than 0.05), while the pressor response to deep breath was slightly enhanced (4.5 +/- 0.8 mm Hg to 6.1 +/- 0.7 mm Hg, p less than 0.05).