Relaxation matters: comparison of in-vitro vasodilatory role of botulinum toxin-A and papaverine in human radial artery grafts

Botulinum Toxin to Improve the Prognosis of Skin Transplantation: A Short Narrative Review

Skin transplantation is a traditional and well-established method of repairing skin loss, especially deep second-degree postburn wounds. Complications often happen amid the healing process, including necrosis and skin contracture, which has raised widespread concern from patients and doctors. Since the first recorded medical application of botulinum toxin for strabismus, accumulating evidence has enclosed all-round potential of botulinum toxin, more than aesthetic management. In recent decades, botulinum toxin also has been revealed to improve the prognosis of skin grafts. This literature review aims to briefly summarize the history and latest advances of its use for skin transplantation.

Botulinum Toxin A and B Improve Perfusion, Increase Flap Survival, Cause Vasodilation, and Prevent Thrombosis: A Systematic Review and Meta-analysis of Controlled Animal Studies

BACKGROUND

A systematic review and meta-analysis of case-control animal model studies will help clarify the vascular effects of botulinum toxin (BTX).

METHODS

Preferred Reporting Items of Systematic reviews and Meta-Analyses guidelines were used to identify all animal case-control studies published before September 13, 2020, evaluating the vascular effects of BTX. Primary parameters included the following: perfusion, flap survival, arterial and venous dilation, and arterial and venous thrombosis.

RESULTS

Thirty-six studies with 1032 animals met the systematic review inclusion criteria. Twenty-nine studies had quantifiable data for statistical analysis. Statistically significant increases in perfusion with BTX over saline were detected within 1 day and sustained up to 8 weeks. The following represent weighted mean data from the meta-analysis. The administration of BTX has a 26% increase in both random pattern and pedicled flap survival area over controls. Botulinum toxin causes vasodilation. Botulinum toxin increases vessel diameter in arteries by 40% and in veins by 46% compared with saline controls. The administration of BTX reduces thrombosis by 85% in arteries and by 79% in veins compared with saline controls. Vascular effects were consistent across both BTX-A and BTX-B serotypes, multiple animal species, and various doses. No clear relationships between vascular effects and BTX pretreatment time were identified.

CONCLUSIONS

Perivascular BTX administration intraoperatively or as a chemical delay pretreatment several days before surgery in multiple animal species and models shows multiple changes to the vascular system. Extrapolation of lessons learned from this systematic review and meta-analysis of animal models could expand research and clinical use of BTX in human vascular disease and surgery.

The effects of botulinum toxin A and papaverine on human saphenous vein and internal mammary artery grafts: an in vitro study

INTRODUCTION

Autologous saphenous vein (SV) and internal mammary artery (IMA) are used as bypass conduits during coronary artery bypass graft surgery. Vasospasm of the arterial and venous grafts may constitute a significant clinical problem. Pretreatment with a vasodilator drug of the graft ex vivo or intraluminal injection before implantation may be used for spasm prophylaxis. This in vitro study was designed to assess the vasoactive effects and time-dependent changes of botulinum toxin A (BTX-A) and papaverine pretreatment on vasospasm of human SV and IMA grafts. Also, histomorphology of the vessels was assessed.

MATERIAL AND METHODS

SV and IMA segments were suspended in organ baths, and isometric contraction responses to 2 different concentrations of 5-hydroxytryptamine (5-HT) and endothelin-1 (ET-1) were recorded after incubation with 2 different concentrations of BTX-A and papaverine at 2 time points (0 h and 2 h).

RESULTS

The results revealed the following: 1) incubation with BTX-A and papaverine relaxes both SV and IMA rings contracted with 5-HT and ET-1; 2) the duration of the relaxant effect of BTX-A lasts longer than papaverine; and 3) no apparent histomorphological changes were observed in the grafts under light microscopy.

CONCLUSIONS

This study demonstrates that in human SV and IMA grafts, pretreatment with both BTX-A and papaverine are safe and have a potent inhibitory effect depending on the vessel and vasoconstrictor agent. The long-lasting vasodilatory effect of BTX-A on vascular smooth muscle may provide promising results in the prevention of venous and arterial graft spasm.

A non-conventional proximal inflow for the radial artery coronary graft

Despite good outcomes, the use of the radial artery as a coronary graft is not widespread. Concerns regarding its low versatility and the risk of hand ischaemia, as well as the lack of reliable information regarding the best storage solution of the graft, and regarding the treatment for preventing spasms have limited its use. In this manuscript, the (numerous) benefits and (few) drawbacks of the proximal inflow for the radial artery from the in situ right internal thoracic artery proximal stump are discussed. Outcomes are reported from a limited series of patients undergoing totally arterial myocardial revascularization using this composite graft and both internal thoracic arteries.