What is the source of anticontractile factor released by the pedicle of human internal thoracic artery?

Vasorelaxing properties of the perivascular tissue of the human radial artery

OBJECTIVES

Perivascular adipose tissue (PVAT) surrounding the human internal thoracic artery exhibits anticontractile and vasorelaxing properties associated with the adipocyte-derived relaxing factor (ADRF). The goal of our study was to assess if perivascular tissue of the human radial artery (RA) also exhibits such anticontractile/vasorelaxant properties. It could be especially relevant in preventing RA spasms.

METHODS

The study was performed on isolated segments of human pedicled RA. Its skeletonized fragments were suspended on stainless steel wire hooks and gradually contracted with serotonin to establish the concentration-effect relationship in the presence/absence of PVAT. Skeletonized arterial segments were precontracted with a single dose of 10-6 M serotonin (EC80). The 5-ml PVAT aliquots (from PVAT incubated in Krebs-Henseleit solution) were transferred to the RA tissue bath resulting in its relaxation. Subsequently, we investigated if ADRF is dependent on endothelial vasorelaxants (nitric oxide and prostacyclin). We attempted to find the potassium channel responsible for mediating the activity of ADRF using different potassium channel blockers.

RESULTS

RA without PVAT contracted more strongly in response to serotonin compared to RA with PVAT [Emax: 108.3 (20.2) vs 76.1 (13.5) mN]. The PVAT aliquot relaxed precontracted RA rings at 43% (2.4%) [72.2 (15.6) to 41.0 (5.6) mN]. ADRF is independent of endothelial vasorelaxants; hence, the addition of NG-monomethyl-l-arginine and indomethacin did not change the vasorelaxant response. Neither of the potassium channel blockers participated in the activity of ADRF.

CONCLUSIONS

PVAT of human RA exhibits anticontractile/vasorelaxant properties that are inherently associated with ADRF secretion. We confirmed the endothelial-independent mechanism of the activity of ADRF. However, we failed to find the potassium channel responsible for the action of ADRF.

Up-to-Date, Skeletonized or Pedicle Bilateral Internal Mammary Artery; Does It Matter?

PURPOSE

In this article, we reported on the up-to-date literature regarding skeletonized bilateral internal mammary artery (BIMA) flow and the effect on sternal perfusion. We also reviewed the pros and cons of the skeletonization technique versus the conventional pedicle technique for harvesting the BIMA.

METHODS

We performed an up-to-date review using the PubMed database, with a specific focus on the contemporary published literature.

RESULTS

BIMA skeletonization can preserve the sternal microcirculation, minimize tissue damage, and maintain blood supply to the chest wall at the tissue level. This effect is also apparent in diabetics. Deep sternal wound infection (DSWI) rates are significantly less with skeletonization versus the conventional pedicle technique and are comparable to single internal mammary artery harvesting.

CONCLUSIONS

Contemporary large-scale studies demonstrate that skeletonization of the BIMA increases conduit length, provides superior flow, reduces the incidence of DSWIs, and improves late survival. Hopefully, this review will increase awareness of the compelling evidence in favor of using skeletonized internal mammary arteries and stimulate increased uptake of BIMA revascularization surgery.