Changes in cardiac function after effective treatment of hypertensive emergencies with i.v. clonidine.

ABSTRACT

Clonidine administration by i.v. infusion in 12 patients with hypertension emergencies (diastolic blood pressure over 130 mmHg) resulted in the normalization of blood pressure (BP) in all patients. Lowering of BP was associated with a reduction in total and lower limb vascular resistance. Heart rate showed a slight and brief decrease. Cardiac performance (determined by radionuclide angiocardiography) was improved as indicated by the significant increase of ejection fraction and decrease of both end-diastolic and end-systolic volumes. The dosage of clonidine was progressively increased until a normal BP (mean BP less than or equal to 105 mmHg) was obtained. In all patients a normal BP was achieved and in none was an initial hypertension effect observed. The total mean dose required for control of BP was 382.5 +/- 98.3 micrograms, administered over a mean period of 26.5 +/- 4.6 min. Side-effects, represented by dry mouth and drowsiness, were well tolerated and of short duration. It is concluded that clonidine is an effective and safe alternative in the treatment of hypertensive emergencies.