The acute effects of intravenous xamoterol ('Corwin', I.C.I. 118, 587) on resting and exercise haemodynamics in patients with mild to moderate heart failure.
The known properties of xamoterol, a partial beta 1-agonist, provide a basis to pharmacologically modulate cardiac responses to variations in sympathetic tone. Haemodynamic variables were assessed at rest and on exercise before and after intravenous xamoterol (0.2 mg kg-1), in 30 patients with mild to moderate cardiac failure. Xamoterol produced significant improvements in resting cardiac index (2.51 +/- 0.15 to 2.80 +/- 0.14 l min-1 m-2; P less than 0.001), stroke volume (62 +/- 4 to 75 +/- 5 mljbeat-1; P less than 0.001) and stroke work index (42.4 +/- 3.6 to 47.7 +/- 3.9 gm beat-1 m-2; P less than 0.01). This occurred despite a significant reduction in heart rate (78 +/- 3 to 74 +/- 2 beats min-1; P less than 0.05). There were also significant reductions in systemic vascular resistance (1990 +/- 141 to 1669 +/- 112 dynes s-1 cm-5; P less than 0.01) and double product (1146 +/- 46 to 1051 +/- 41 mmHg min-1 x 10(-1); P less than 0.05), with no significant changes in systolic blood pressure, pulmonary wedge pressure or ejection fraction. Xamoterol significantly attenuated the heart rate response to exercise (112 +/- 4 to 97 +/- 3 beats min-1; P less than 0.001), with no impairment in the expected exercise induced increase in cardiac index. This was due to the significant increase in stroke volume from 81 +/- 6 to 95 +/- 7 ml beat-1 (P less than 0.001). There were no significant changes in resting or exercise noradrenaline levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Virk
S J
SJ
Department of Cardiovascular Medicine, University of Birmingham, East Birmingham Hospital, U.K.
Anfilogoff
N H
NH
Lawson
N
N
Sadler
A M
AM
Smith
S J
SJ
Nuttall
A
A
Murray
R G
RG
Littler
W A
WA
Davies
M K
MK
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D004341:Drug Evaluation; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000188:drug therapy / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects; D017307:Xamoterol
D000318:Adrenergic beta-Agonists; D011412:Propanolamines; D017307:Xamoterol