The effect of long-term beta-adrenergic receptor blockade on the oxygen delivery and extraction relationship in patients with coronary artery disease.
OBJECTIVE
We evaluated the effects of long-term beta-blocker treatment on the balance between oxygen delivery and extraction at peak oxygen uptake (VO2) and at target heart rate training (anaerobic threshold).


METHODS
Fifteen patients with coronary artery disease performed paired peak cardiopulmonary and submaximal exercise tests on a cycle ergometer with and without atenolol treatment. Thirty minutes following the submaximal tests, participants pedaled 10 minutes at a workload corresponding to that of the anaerobic threshold attained. Arterial oxygen was defined from echocardiography and venous oxygen content.


RESULTS
At rest, stroke volume, heart rate, and cardiac output were lower (P < .05), whereas arteriovenous oxygen difference [(a - v)O2] was higher with the use of atenolol (P < .05). At peak exercise, heart rate, lactate, and systolic blood pressure were lower (P < .05), whereas (a - v)O2 was higher (P < .05) with the use of atenolol. At anaerobic threshold, stroke volume, heart rate, cardiac output, and systolic blood pressure were lower (P < .05), whereas (a - v)O2 was higher (P < .05) with the use of atenolol. Absolute VO2 and workload during maximal (P = .67 and P = .49, respectively) and submaximal (P = .13 and P = .44, respectively) exercises were similar between conditions.


CONCLUSIONS
Results demonstrate that atenolol treatment in patients with coronary artery disease does not alter VO2 and workload at the anaerobic threshold and peak exercise because of an increase in oxygen extraction and stroke volume in the face of reduced heart rate. These findings indicate that with long-term beta-adrenergic receptor blockade, there is interplay between oxygen delivery and extraction, suggesting a link between cardiac hemodynamic responses and skeletal muscle metabolic adaptations.
Eynon
Nir
N
Sports Medicine and Rehabilitation Division, the Zinman College of Physical Education and Sport Sciences, Wingate Institute, Netanya, Israel.
Sagiv
Moran
M
Amir
Offer
O
Ben-Sira
David
D
Goldhammer
Ehud
E
Amir
Ruthie
R
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D001262:Atenolol / Q000627:therapeutic use*; D002302:Cardiac Output; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D012146:Rest; D013318:Stroke Volume; D013997:Time Factors; D014463:Ultrasonography
D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D010100:Oxygen