Pulmonary metabolism of endothelin 1 during on-pump and beating heart coronary artery bypass operations.
BACKGROUND
Coronary artery bypass operations are associated with increased circulating levels of the powerful vasoconstrictor endothelin 1. The pulmonary circulation is an important site for both production and clearance of endothelin 1. Lung endothelial injury resulting from cardiopulmonary bypass could modify pulmonary endothelin 1 metabolism through an increase in production, a reduction in removal, or a combination of both.


METHODS
Pulmonary endothelin 1 kinetics were quantified by using the indicator-dilution technique in patients undergoing coronary artery bypass grafting with (n = 11) or without cardiopulmonary bypass (ie, beating heart; n = 10). Mixed venous endothelin 1 levels were also measured in samples from the pulmonary artery, and systemic levels were obtained from the radial artery.


RESULTS
Pulmonary artery endothelin 1 levels were similar before and after cardiopulmonary bypass, with means of 1.59 +/- 0.37 pg/mL and 1.33 +/- 0.15 pg/mL (P =.45), respectively. Systemic endothelin 1 levels, however, increased after bypass from 1.64 +/- 0.22 pg/mL to 2.07 +/- 0.16 pg/mL (P =.01). In the beating heart group, endothelin 1 levels before and after the operation were similar in the pulmonary artery (1.25 +/- 0.27 pg/mL and 1.45 +/- 0.31 pg/mL, respectively; P =.38), as well as in the radial artery (1.70 +/- 0.26 pg/mL and 1.73 +/- 0.35 pg/mL, respectively; P =.92). The capacity to clear endothelin 1 from the pulmonary circulation, as computed from the permeability-surface area product for endothelin 1, was not affected by cardiopulmonary bypass before and after the operation (25.19 +/- 2.67 mL/s and 23.12 +/- 4.39 mL/s, respectively; P =.49). It was similar and also unaffected in the beating heart group.


CONCLUSIONS
Coronary artery bypass grafting with cardiopulmonary bypass is associated with an increase in systemic endothelin 1 levels. The mechanism involved is not related to a decreased pulmonary clearance of endothelin 1 from the systemic circulation but rather to an increased endothelin 1 release by the lungs.
Mathieu
P
P
Department of Surgery, Montreal Heart Institute, 5000 Belanger St. E, Montreal, Quebec H1T 1C8, Canada.
Dupuis
J
J
Carrier
M
M
Cernacek
P
P
Pellerin
M
M
Perrault
L P
LP
Cartier
R
R
Taillefer
J
J
Pelletier
L C
LC
D000368:Aged; D002315:Cardiopulmonary Bypass / Q000379:methods*; D001026:Coronary Artery Bypass / Q000379:methods*; D003327:Coronary Disease / Q000601:surgery; D019332:Endothelin-1 / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011300:Preoperative Care; D011651:Pulmonary Artery / Q000737:chemistry; D017534:Radial Artery / Q000737:chemistry; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016896:Treatment Outcome
D019332:Endothelin-1