What are angiosomes and how do they impact lower leg wound healing?
This article covers the history of angiosomes and how they relate to current revascularization practices.
Angiosomes - what are they?
The angiosome is a concept developed by Taylor and Palmer to aid in improving flap reconstructive surgeries (1). An angiosome describes a composite unit of skin and underlying deep tissue that is supplied by a source artery (1).
Angiosome image courtesy of: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International. Reference (2)
The researchers found 40 angiosomes in the body during their injection dye studies into the vasculature of cadavers and multiple limbs (1, 2). Two main categories of vessels were uncovered (1):
Direct vessels that constitute the primary cutaneous supply, their main destination is the skin.
Indirect vessels that constitute the secondary cutaneous supply, emerging from the deep fascia as branches of arteries with the main purpose of supplying the muscles and other deep tissues.
Choke vessels
They also found that adjacent source arteries and their branches are linked to form a continuous network of vessels regardless of the tissue – these connections were termed choke vessels (1).
The researchers did note that the boundaries between angiosomes can be blurred due to the ‘choke zones’ where these vessels are situated, it was also clear that the majority of muscles are supplied by multiple angiosomes (1). The overlay of angiosomes and choke vessels can be seen in image A and B (4).
Choke vessels are essentially the human body’s back up systems for blood flow should a compromise occur to the main source artery. The vessels become support for the primary supply, as reinforcements and as true redundant vessels (3).
Image shared with permission from Elsevier. Reference (4).
“It spans the entire body like a national map of roadways and subways made up of interconnecting channels of all sizes.”
how do angiosomes relate to wound care?
Specific to the lower limb, there are six main angiosomes that originate from the popliteal artery and branch out to the foot and toes. Three then branch from the tibialis posterior artery, two from the peroneal artery, and one from tibialis anterior artery (3, 5, 6).
In revascularization procedures according to the angiosomal model, completing direct or indirect revascularization depends on if the procedure addresses the source artery that supplies blood to the area of tissue loss. Direct revascularization is achieved when the source artery is addressed, whereas indirect revascularization does not achieve this (6, 7).
Angiosomal-based revascularization has been proposed over the years to improve outcomes in the presence of severe ischemia and revascularization (8). Using angiosomes to aid in decision making of surgery procedures has shown positive effects in ulcer healing and limb preservation therapy in CLTI (9).
Image courtesy of CCF 2014.
angiosome-based revascularization in practice
Although there is no current consensus on the best practice for revascularization techniques for PAD, diabetic foot ulcers (DFUs) or tissue loss (8), the trend is in the direction of aiming for an angiosomal-targeted revascularization whenever possible (3).
When using clinical judgement to determine revascularization procedures, the entire patient profile must be taken into account – type of wound, comorbidities, aging, underlying pathology, and importantly, blood flow to the area (3). This will differ per patient due to aforementioned factors, but also due to the degree of variance of angiosomes, collaterals and choke vessels in each patient (8). According to one study (8), only 36% of wounds could be sourced to a single angiosome, while ~20% of DFUs and >50% of toe wounds were sourced from multiple.
It has been suggested that more individualized techniques be used during the revascularization treatment plan (10). The anatomic description of angiosomes can be a starting point which can then be adapted to the patient’s ‘real angiosome’ which takes into account their disease, condition, comorbidities, choke vessels and collateral vessels (3). This treatment plan allows the possibility of direct revascularization to be the first-choice treatment, while providing room for the care team to pivot to indirect revascularization as necessary (9).
Table 1 and the following image lay out the ‘typical’ angiosomes, their source artery and the branches into the dorsal and plantar surfaces of the foot (11). These angiosomes can be taken into consideration when creating a care protocol for a revascularization patient.
Okazaki, Jin & Ishida, Masaru & Kuma, Sosei & Morisaki, Koichi 2015. Reference (11).
angiosomal-targeted treatment plans
Using angiosomes as a guide for a treatment plan can be effective in reaching an individualized treatment that considers direct revascularization which can promote ulcer healing, reduce amputation rate, and increase survival rate (9). The other benefit of angiosomal-based revascularization is the adaptability of the process – for patients who were not candidates for direct revascularization, they can be converted to indirect revascularization which can achieve a similar result if the patient has abundant collaterals (9).
References:
1. Taylor GI, Palmer JH. The vascular territories (angiosomes) of the body: experimental study and clinical applications. Br J Plast Surg. 1987 Mar;40(2):113-41. doi: 10.1016/0007-1226(87)90185-8. PMID: 3567445.
2. Woo, Soo Jin & Koo, Hee & Park, Seong & Suami, Hiroo & Chang, Hak. (2022). Evolution of Anatomical Studies on the Arterial, Venous, and Lymphatic System in Plastic Surgery. Archives of Plastic Surgery. 49. 773-781. 10.1055/s-0042-1758636. Adapted from the original version by Taylor and Palmer 1987.
3. van den Berg, J.C., 2018, June. Angiosome perfusion of the foot: An old theory or a new issue?. In Seminars in vascular surgery (Vol. 31, No. 2-4, pp. 56-65). WB Saunders.
4. Aicher, Brittany & Woodall, J. & Tolaymat, Besher & Calvert, C. & Monahan, Thomas & Toursavadkohi, S.. (2021). Does perfusion matter? Preoperative prediction of incisional hernia development. Hernia. 25. 10.1007/s10029-019-02018-3.
5. Wong, A. & Morris S. F. (2022). Vascular Anatomy of the Lower Extremity: A Practical Guide to Vascular Territories, Perforators, and Selection of Recipient Vessels. Plastic Surgery Key. Available at https://plasticsurgerykey.com/vascular-anatomy-of-the-lower-extremity-a-practical-guide-to-vascular-territories-perforators-and-selection-of-recipient-vessels/ (Accessed February 27 2024).
6. Stimpson, A.L., Dilaver, N., Bosanquet, D.C., Ambler, G.K. and Twine, C.P., 2019. Angiosome specific revascularisation: does the evidence support it?. European Journal of Vascular and Endovascular Surgery, 57(2), pp.311-317.
7. Tange, F.P., Ferrari, B.R., van den Hoven, P., van Schaik, J., Schepers, A., van Rijswijk, C.S., van der Meer, R.W., Putter, H., Vahrmeijer, A.L., Hamming, J.F. and van der Vorst, J.R., 2023. Evaluation of the Angiosome Concept Using Near-Infrared Fluorescence Imaging with Indocyanine Green. Annals of Vascular Surgery, 93, pp.283-290.
8. Chuter, V., Schaper, N., Mills, J., Hinchliffe, R., Russell, D., Azuma, N., Behrendt, C.A., Boyko, E.J., Conte, M.S., Humphries, M.D. and Kirksey, L., 2023. Effectiveness of revascularisation for the ulcerated foot in patients with diabetes and peripheral artery disease: A systematic review. Diabetes/metabolism research and reviews, p.e3700.
9. Hou, X., Guo, P., Cai, F., Lin, Y. and Zhang, J., 2022. Angiosome-guided endovascular revascularization for treatment of diabetic foot ulcers with peripheral artery disease. Annals of Vascular Surgery, 86, pp.242-250.
10. Brodmann, M. (2013). The Angiosome Concept in Clinical Practice - Implications for patient-specific recanalization procedures. Endovascular Today. Available at https://evtoday.com/articles/2013-may/the-angiosome-concept-in-clinical-practice. (Accessed February 27 2024).
11. Okazaki, Jin & Ishida, Masaru & Kuma, Sosei & Morisaki, Koichi. (2015). Infrapopliteal Bifurcated Dual Run-off Bypass in Critical Limb Ischemia: A Report of 2 Cases. Annals of Vascular Surgery. 29. 10.1016/j.avsg.2015.01.024.