Preliminary experience in the use of preoperative echo-guided left stellate ganglion block in patients undergoing cardiac surgery.

OBJECTIVE

Pulmonary arterial (PA) vasoconstriction in cardiac surgery can originate from the action of combined humoral, endothelial, and sympathetic tone changes. The consequence of PA vasoconstriction is pulmonary hypertension (PHT) and, when present after cardiopulmonary bypass (CPB), can predispose to right ventricular dysfunction. Right ventricular dysfunction after CPB is a serious complication with high mortality rates. The extent to which sympathetic blockade could reduce PA vasoconstriction and reduce PHT is unknown. Pharmacologic stellate ganglion block (SGB) has been associated with a reduction in PHT, but its role and mechanism in cardiac surgery have not been described. Thus, the goal of the study was to test the hypothesis that echo-guided left SGB, performed before the induction of general anesthesia, could prevent PA pressure increases during CPB weaning.

DESIGN

A prospective cohort study in cardiac surgical patients.

SETTING

A tertiary care university hospital.

PARTICIPANTS

Forty cardiac surgical patients.

INTERVENTIONS

A left SGB was performed immediately before the induction of general anesthesia under ultrasound guidance and was compared with matched control patients. Standard hemodynamic and electrocardiographic monitoring was performed, and blood gas samples were drawn at specific predetermined time points for analysis. Rhythm disorders, echocardiographic parameters that included wall motion abnormalities, and biochemical parameters of myocardial ischemia were measured by an observer blinded to the allocated group.

MEASUREMENTS AND MAIN RESULTS

Marked improvement in the PaO(2)/F(I)O(2) ratio in the SGB group was observed (mean difference = 77 mmHg, p = 0.0001). There were no differences between the groups in PA pressure over time during the procedure; central venous pressure was higher in the SGB group (p =0.0184). Reductions of right ventricular fractional area change (p = 0.0331) and tricuspid annulus displacement (p = 0.0048) were observed in the SGB group. The CK-MB was 1.5 times higher in the SGB group (p = 0.0211), but no patients developed myocardial infarction.

CONCLUSIONS

Left SBG was associated with improved oxygenation that could partially explain its mechanism in acute PHT. Further studies are necessary to evaluate the usefulness of this technique in patients with a high risk of PHT during separation from CPB.