Will off-pump coronary artery surgery replace conventional coronary artery surgery?

Modulation of the cellular and humoral immune response to pediatric open heart surgery by methylprednisolone

BACKGROUND

With the intention to reduce overshooting immune response, glucocorticoids are frequently administered perioperatively in children undergoing open heart surgery. In a retrospective study we investigated extensively the modulation of the humoral and cellular immune response by methylprednisolone (MP).

METHODS

This study was carried out on blood samples from two groups of children who had undergone surgical correction of atrial or ventricular septal defects, either without (MP⁻, n = 10), or with MP administration (MP+, n = 23, dose median 11 (IQR 10-16) mg kg⁻¹ body weight) before cardiopulmonary bypass (CPB, duration median 42 (IQR 36-65) min). EDTA blood was obtained 24 h preoperatively, after anesthesia, at CPB begin and end, 4, 24, and 48 h after surgery, at discharge and at out-patient follow-up (median 8.2 (IQR 3.3-12.2) months after surgery). Complex blood analysis including clinical chemistry and flow cytometry were performed to monitor humoral immune response, differential blood count, lymphocyte subsets, and the degree of activation of various leukocyte subpopulations.

RESULTS

The patients' postoperative courses and follow-up were uneventful. Release of IL-6 and IL8 was reduced and that of the anti-inflammatory cytokine IL-10 upregulated by MP. Significant increase of circulating neutrophils and monocytes as inflammatory reaction to surgery and CPB contact was detected in both groups. However, invasion of monocytes to the periphery was delayed with MP. CD4+ and CD8+ T-lymphocyte counts were lower with MP treatment. B-lymphocyte count increased significantly after surgery in MP+ but remained constant in MP⁻ group.

CONCLUSIONS

MP treatment partially decreased the pro-inflammatory effect of CPB surgery and induced anti-inflammatory effect on the cellular and humoral level.

Vacuum-assisted apical suction devices induce passive electrical changes consistent with myocardial ischemia during off-pump coronary artery bypass graft surgery

OBJECTIVE

Off-pump coronary artery bypass graft surgery is common therapy to completely revascularize diseased hearts. In order to graft posterior arteries in this procedure, the heart must be lifted from the chest cavity and manipulated to expose the surgical field using an apical suction device. This suction device may cause unwanted myocardial ischemia.

METHODS

In this observational study, we measured myocardial electrical impedance, a parameter that responds to myocardial ischemia, as well as ST-segment changes during off-pump coronary artery bypass graft surgery in 12 patients with two-vessel coronary artery disease undergoing revascularisation of the left anterior descending and the posterior descending coronary arteries. During the posterior descending artery revascularisation phase of the procedure the apical suction device was oriented over the electrodes used to measure myocardial electrical impedance, thus allowing us the opportunity to assess myocardial ischemia in this region of the heart.

RESULTS

In these 12 patients, myocardial electrical impedance progressively increased under the suction device during posterior coronary artery revascularisation, suggesting that myocardial ischemia developed in this region of the myocardium. ST-segment changes were negligible while the heart was vertically displaced (and the suction device attached), but increased immediately when the heart was returned to the neutral anatomical position.

CONCLUSION

Our data suggest that the apical suction device may cause ischemia while the heart is vertically displaced and electrically disconnected from the body. Under these conditions, ST-segment changes may not detect myocardial ischemia. Myocardial electrical impedance has the potential to reliably detect intraoperative myocardial ischemia under these circumstances.