HEMODYNAMIC COMPARISON OF AMLODIPINE AND ATENOLOL IN ESSENTIAL-HYPERTENSION USING THE QUANTASCOPE

1 We have utilised a non-imaging echo-Doppler cardiac output device, u sing the principle of attenuated compensation volume flow (ACVF), to a ssess the cardiovascular effects of amlodipine and atenolol over 3 mon ths 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 eac h vs baseline). 3 The heart rate fell on atenolol, both at 4 weeks (am lodipine -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 v olume 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 resis tance 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 re sults are consistent with contrasting mechanisms of action - vasodilat or for amlodipine and decreased cardiac pumping for atenolol. The grea ter reduction in cardiac stroke work on amlodipine compared with ateno lol warrants further investigation during longer-term studies.