Περίληψη:
We sought to assess the haemodynamic effects of clonidine on left
ventricular (LV) pressure-volume relation in patients with diastolic
heart dysfunction due to essential hypertension. Towards this end,
simultaneous recordings of LV volume (acoustic quantification) and LV
pressure (micromanometer) were obtained in 10 such patients before and
after drug administration and compared to baseline findings on 10
matched normal controls. The following measurements and calculations
were obtained: maximal positive and negative first derivative of LV
pressure (peak +dP/dt and peak -dP/dt, respectively), LV minimal and
end-diastolic pressure, peak systolic blood pressure, time constant of
relaxation (TAU), LV stroke work and LV stiffness constant. The two
invasive indexes, LV stiffness constant and TAU classified 10/10
patients as having abnormal LV diastolic function compared with 7/10
patients so classified by Doppler studies. Central sympathetic
suppression by a single oral dose of clonidine 0.125 mg in heart rate
and mean arterial pressure as well as a significant improvement of LV
diastolic function indexes. Specifically, the LV stiffness constant
(ml(-1)), in normal subjects was 0.0028 vs 0.0152 (P<0.001) in
hypertensive subjects at baseline, vs 0.0053 in hypertensive after
clonidine (P<0.001 vs baseline). Likewise, the E/A ratio, was 1.08 in
normal subjects vs 0.88 (P<0.0001) in hypertensives at baseline, vs 1.28
in hypertensives after clonidine (P<0.0001 vs baseline). With clonidine
the diastolic portion of the pressure-volume curve was displaced
downward. In conclusion, clonidine can improve diastolic dysfunction
without depressing systolic LV performance. The improvement may be
attributable in part to withdrawal of direct sympathetic influence on
the myocardium and in part to the indirect effect of systemic, pulmonary
and coronary artery relaxation.
Συγγραφείς:
Stefanadis, C
Manolis, A
Dernellis, J
Tsioufis, C and
Tsiamis, E
Gavras, I
Gavras, H
Toutouzas, P
