title: Systemic vascular resistance during brief withdrawal of angiotensin converting enzyme inhibition in heart failure.
abstract: We tested the hypothesis that moderate increases in endogenous angiotensin II (Ang II) concentrations, induced by withdrawal of angiotensin converting enzyme inhibition (ACE-I) in patients with compensated heart failure (HF) on chronic medical therapy, do not increase or impair control of systemic vascular resistance (SVR). SVR was determined in supine and seated positions in 12 HF patients [NYHA class II-III; ejection fraction=0.29 +/- 0.03 (mean +/- SE)] and 9 control subjects. HF patients were investigated during high (n=11; withdrawal of ACE-I treatment for 24 h) and low (n=9; sustained ACE-I therapy) endogenous plasma Ang II concentrations. Withdrawal of ACE-I therapy in HF caused moderately increased Ang II concentrations of 30 +/- 5 pg/ml compared with 12 +/- 2 pg/ml in controls (p<0.05 vs. HF patients). Despite this, SVR was similar in HF (supine: 1503 +/- 159; seated: 1957 +/- 262 dyn s/cm5, p<0.05 vs. supine) and controls (supine: 1438 +/- 104; seated: 1847 +/- 127 dyn s/cm5, p<0.05 vs. supine). During sustained ACE-I therapy in HF, plasma Ang II concentrations were lower (6 +/- 2pg/ml, p<0.05 vs. withdrawal of ACE-I in HF) with no effect on supine SVR. However, the posture-induced increase in SVR in response to the seated position was attenuated. In conclusion, brief moderate increases in circulating plasma Ang II concentrations in compensated HF do not increase SVR compared to control subjects or impair control of SVR in response to a posture change.
authors.affiliation: Department of Aviation Medicine, The Heart Centre, National University Hospital Rigshospitalet, Copenhagen, Denmark. Anders.Garbielsen@cmm.ki.se
authors.forename: A
authors.initials: A
authors.lastname: Gabrielsen
authors.forename: P
authors.initials: P
authors.lastname: Bie
authors.forename: N J
authors.initials: NJ
authors.lastname: Christensen
authors.forename: E
authors.initials: E
authors.lastname: Frandsen
authors.forename: S
authors.initials: S
authors.lastname: Galatius
authors.forename: B
authors.initials: B
authors.lastname: Pump
authors.forename: V B
authors.initials: VB
authors.lastname: Sørensen
authors.forename: J
authors.initials: J
authors.lastname: Kastrup
authors.forename: P
authors.initials: P
authors.lastname: Norsk
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D006333:Heart Failure / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects*
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors