Selective endothelin-1 receptor type A inhibition in subjects undergoing cardiac surgery with preexisting left ventricular dysfunction: Influence on early postoperative hemodynamics

Does Preoperative Plasma Endothelin-1 Level Influences the Postoperative Events in Patients Undergoing Coronary Artery Bypass Grafting (CABG)? Revisiting Endothelin-1 Molecule in CABG Patients

Endothelin-1 (ET-1) is a powerful physiological vasoconstrictor release in response to endothelial injury. Increased synthesis of endothelin is associated with myocardial ischemia and reperfusion injury. The normal level varies between 0.2 and 18.5 pg/mL that maintains normal vascular homeostasis. We hypothesized that there exists a correlation between ET-1 and clinical outcome in patient undergoing elective coronary artery bypass grafting (CABG) surgery under cardiopulmonary bypass.

Fifty-eight patients undergoing elective on-pump CABG were enrolled in the study. Blood sample for plasma ET-1 was taken before anesthesia induction. The median ET-1 level was 5 pg/mL (range: 0.6–30.33 pg/mL). The inotropic and intraaortic balloon pump requirement was significantly higher among patients having baseline ET-1 level more than 14.24pg/mL (p = 0.001in each case). A similar finding was observed in the duration of mechanical ventilation, intensive care unit stay, and duration of hospital stay (r = 0.68, p = 0.000; r = 0.58, p = 0.000; and r = 0.61, p = 0.000 respectively). The occurrence of complications was also more in individuals with higher baseline ET-1 level. The p-value was significant for occurrence infection, arrhythmia, renal and respiratory problems as observed in postoperative period by using Mann–Whitney U test.

This study concludes that higher level of preoperative ET-1 levels correlates well to adverse clinical outcome in patients undergoing on-pump CABG surgery, so herein it can be used as a single independent parameter to predict postoperative outcome.

Endothelin and vasopressin influence splanchnic blood flow distribution during and after cardiopulmonary bypass

OBJECTIVE

Gastrointestinal blood flow can be compromised during and after cardiopulmonary bypass. Endothelin has been shown to be involved in the intestinal microcirculatory disturbance of sepsis. The aim of the present study was to analyze the involvement of the endothelin system on intestinal blood flow regulation during cardiopulmonary bypass and the effect of vasopressin given during cardiopulmonary bypass.

METHODS

A total of 24 pigs were studied in 4 groups (n = 6): group I, sham; group II, ischemia/reperfusion with 1 hour of superior mesenteric artery occlusion; group III, cardiopulmonary bypass for 1 hour; and group IV, 1 hour of cardiopulmonary bypass plus vasopressin administration, maintaining the baseline arterial pressure. All the pigs were reperfused for 90 minutes. During the experiment, the hemodynamics and jejunal microcirculation were measured continuously. The jejunal mucosal expression of endothelin-1 and its receptor subtypes A and B were determined using polymerase chain reaction.

RESULTS

During cardiopulmonary bypass, superior mesenteric artery flow was preserved but marked jejunal microvascular impairment occurred compared with baseline (mucosal capillary density, 192.2 ± 5.4 vs 150.8 ± 5.1 cm/cm(2); P = .005; tissue blood flow, 501.7 ± 39.3 vs 332.3 ± 27.9 AU; P = .025). The expression of endothelin-1 after cardiopulmonary bypass (3.2 ± 0.4 vs 12.2 ± 0.8 RQ, P = .006) and endothelin subtype A (0.7 ± 0.2 vs 2.4 ± 0.6 RQ; P = .01) was significantly increased compared to the sham group. Vasopressin administration during cardiopulmonary bypass led to normal capillary density (189.9 ± 3.9 vs 178.0 ± 6.3; P = .1) and tissue blood flow (501.7 ± 39.3 vs 494.7 ± 44.4 AU; P = .4) compared with baseline. The expression of endothelin-1 (3.2 ± 0.4 vs 1.8 ± 0.3 RQ; P = .3) and endothelin subtype A (0.7 ± 0.2 vs 0.9 ± 0.2 RQ; P = .5) was not different from the sham group.

CONCLUSIONS

Cardiopulmonary bypass leads to microvascular impairment of jejunal microcirculation, which is associated with the upregulation of endothelin-1 and endothelin subtype A. The administration of vasopressin minimizes these cardiopulmonary bypass-associated alterations.