Macrovascular arteriovenous shunts (MAS): A newly identified structure in the abdominal wall with implications for thermoregulation and free tissue transfer

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Summary

Microscopic arteriovenous anastomoses are known structures that have many clinical implications, with disease states such as Reynaud's phenomenon and erythromelalgia known consequences of their abnormal functioning. These pre-capillary arteriovenous communications result in increased regional blood flow at the time of capillary filling. Recent advances in imaging technology, providing physiological and anatomical data, have identified a previously undescribed anatomical structure, that of large-vessel (macroscopic) arteriovenous communications, with profoundly different implications. Computed tomographic angiography (CTA) of the abdominal wall vasculature was undertaken in 140 patients prior to reconstructive surgery. All scans were arterial phase, demonstrating functional arteriovenous communications in all patients. These communications identified vascular shunting occurring prior to capillary filling. Fine-cut slices were able to visualise the structures, demonstrate their size as macroscopic (>1 mm diameter) and map the course of the arteriovenous communications. The potential clinical implications and therapeutic possibilities in a range of medical and surgical conditions are described.

Section snippets

Methods

A clinical study reviewing 140 preoperative CTA imaging studies of the abdominal wall vasculature was undertaken. These comprised consecutive patients undergoing deep inferior epigastric artery (DIEA) perforator flaps for breast reconstruction during the period between January 2006 and October 2008. All patients were recruited and imaged at a single institution. All patients were female, spanned a range of body habitus types, and were between the ages of 30–70.

A single imaging protocol was used

Results

Upon review of all 140 CTA imaging studies, it was found that the SIEV was contrast filled in all cases. In 137 cases, all cutaneous arteries (DIEA, DIEA perforators and the SIEA) were contrast filled and the only contrast-filled cutaneous vein was the SIEV. In the remaining 3 cases, the DIEV was also filled with contrast.

This phenomenon is highlighted in Figure 1, in which the cutaneous arteries are shown to be contrast-filled, as is the SIEV. Notably, the DIEV is not identifiable. Figure 2A

Discussion

The current study has identified in-vivo evidence of a cutaneous shunt between the arterial perforators of the abdominal wall integument and the superficial venous drainage of the abdominal wall using CTA. This physiological phenomenon was present in all cases, and confirms the presence of a universal non-capillary AVA shunt. As all patients demonstrated evidence of this vascular shunt, it can be assumed that this phenomenon is not due to an abnormal arteriovenous fistula or other anomaly;

Conflict of interest

None. There are no financial and personal relationships with other people or organisations that could inappropriately influence (bias) this work.

Acknowledgements

Dr Damien Stella, Director of CT, Department of Radiology, Royal Melbourne Hospital, Parkville, Victoria, Australia.

Ms Cara Michelle Le Roux, Research Fellow, Jack Brockhoff Reconstructive Plastic Surgery Research Unit, Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, Victoria, Australia.

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