Haemodynamic comparison of amlodipine and atenolol in essential hypertension using the quantascope.
1 We have utilised a non-imaging echo-Doppler cardiac output device, using the principle of attenuated compensation volume flow (ACVF), to assess the cardiovascular effects of amlodipine and atenolol over 3 months in 24 patients with essential hypertension. 2 Both amlodipine and atenolol, at 4 and 12 weeks, similarly reduced mean arterial pressure (12 weeks amlodipine -12.6 mmHg, atenolol -14.9 mmHg; P < 0.01 for each vs baseline). 3 The heart rate fell on atenolol, both at 4 weeks (amlodipine -3 vs atenolol -12 beats min(-1); P < 0.05) and 12 weeks (-1 vs -11 beats min(-1); P < 0.05), without change on amlodipine. 4 Stroke volume initially rose on atenolol without change on amlodipine (4 weeks amlodipine -1.3 ml vs atenolol +10.1 ml; P = 0.05) but between drug effects were not different at 12 weeks. 5 The systemic vascular resistance was reduced on amlodipine (12 weeks: amlodipine -176 dyn s cm(-5): P < 0.05) without change on atenolol (atenolol -48 dyn s cm(-5): NS). 6 The cardiac stroke work was lowered on amlodipine both at 4 weeks (P < 0.01) and 12 weeks (P < 0.05) and statistically different from the unaltered atenolol values at both time points. 7 Skin nutrient flow or fingertip temperature was not altered by either treatment. 8 These results are consistent with contrasting mechanisms of action--vasodilator for amlodipine and decreased cardiac pumping for atenolol. The greater reduction in cardiac stroke work on amlodipine compared with atenolol warrants further investigation during longer-term studies.
Tham
T C
TC
Department of Therapeutics and Pharmacology, Queen's University of Belfast, Belfast, Northern Ireland.
Herity
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N
Guy
S
S
Silke
B
B
D017311:Amlodipine / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001262:Atenolol / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008875:Middle Aged; D013318:Stroke Volume / Q000187:drug effects; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance / Q000187:drug effects
D000959:Antihypertensive Agents; D017311:Amlodipine; D001262:Atenolol