Invited Discussion: “New approach to vascular injection in fresh cadaver dissection” (J Reconstr Microsurg 2004;20:311-315)

Dr. Heymans and colleagues describe a cadaver injection technique using yellow lead oxide, which they state is Pb₃O₄, mixed with gelatine and used to define the arterial network of the face and limbs. They found in dissections of the vasculature that it was difficult to define the vessels from the yellow fat, so they stained the lead oxide with rhodamine B to give a pink mixture. To define the terminal branches supplying the nose, they modified their technique. They mixed methylene blue with gelatine, first injecting this proximally into the facial artery. The artery was then cannulated just prior to its lateral nasal branch and injected with the radiopaque lead oxide-gelatine mixture, providing fine detail of the arterial network of the nasal tip to define the “micro-angiosome” of this vessel.

I would like to compliment the authors on some of their results especially Figure [2], but also wish to draw attention to two points. The first is the color of their lead oxide mixture, and the second is the interpretation of their results.

The Pb₃O₄ lead oxide, minimum or red lead as originally described and used by Salmon in the 1930s[1] [2] [3] [4] [5] and later used by us in our studies of the angiosomes,[6] [7] is orange [8] not yellow, as stated by the authors. The PbO form of lead oxide is yellow,[9] and it is likely that this was the compound used by Dr Heymans and his coworkers, not Pb₃O₄ (Fig. [1]). Because Pb₃O₄ is bright orange or red, it clearly stains the dermis, is easy to dissect when mixed with gelatine, and thus obviates the need for additives.

Figure 1 (A) The orange Pb₃O₄ and yellow PbO lead oxide and (B) a study of the posterior tibial vena comitantes injected with orange Pb₃O₄ that are interconnected by the vasa vasora that surround the central artery.

Furthermore, we have had no trouble defining the fine vasculature of the arterial network, even though our lead oxide-gelatine mixture was introduced into major vessels such as the femoral or carotid arteries. The lead oxide tends to precipitate in the mixture, which must be warmed and stirred constantly.[10] With experience, the thinner supernatant mixture can be used to define the fine vessel architecture, which sometimes even overflows into the veins (Fig. [2]). If the main branches only are required, the thicker precipitate “sludge” can be used from the bottom of the container to define the source arteries and their main ramifications. Like the authors, we started initially with barium sulphate and later, after learning of Salmon's work, changed to lead oxide with superior results.[10]

Figure 2 (A) Radiograph of the skin of the face in anterior and (B) lateral views after total body injection of the cadaver with Pb₃O₄. The (a) facial and (b) ophthalmic arteries are labelled, as are the (c) facial veins, in each study. Note the anastomosis between the branches of the facial artery of each side in the lips and tip of the nose which define the boundary between these two angiosomes, as well as their connections with branches of the ophthalmic artery on the bridge of the nose. (From Houseman ND, Taylor GI, Pan WR. The angiosomes of the head and neck: anatomic study and clinical applications. Plast Reconstr Surg 2000;105:2287-2313. Reprinted with permission of © Lippincott Williams & Wilkins.)

An angiosome, by definition, is an anatomic not a physiologic territory, although it certainly plays a major role in tissue survival when several are raised in series in a flap. The boundaries of angiosomes, whether major or minor (micro-angiosomes) are defined by lines drawn across the anastomotic vessels-whether reduced caliber “choke” vessels or true anastomoses without change in caliber-which link neighboring vascular territories in all tissue layers. In our studies, the entire body was injected and hence all vascular territories were outlined, so that the individual angiosomes of the various source arteries could be mapped separately.

However, if a single source vessel alone is injected, as was done by the authors and is seen in their Figure [2], the injectant will overflow into the adjacent anatomic vascular territories in all directions via the “choke” or “true” anastomotic vessels. This is because there is no pressure buffer effect from adjacent arteries, as occurs in the living state. The injectant simply follows the line of least resistance, spilling into the branches and then the trunks of the neighboring source arteries. Hence there will be an over estimate and misleading picture of the anatomic vascular territory of the vessel under examination - in this case the facial artery. By comparing the authors' Figure [2] with our Figure [2], it can be seen that the injected facial artery on the left side of their subject has overflowed into the opposite facial artery and its branches, as well as the opposite ophthalmic artery.

With the current vogue for “perforator flaps,” there will once again be another renaissance and reappraisal of vascular anatomy in the search for new flaps based on specific vessels. The use of the lead oxide-gelatine mixture in cadaver studies, preferably using the orange Pb₃O₄ compound, will once again be a valuable aid in defining the vasculature, as highlighted by the authors.

REFERENCES

• 1 Salmon M, Dor J. Les Artères des Muscles des Membres et du Tronc . Paris; Masson 1933
• 2 Salmon M. Artères de la Peau: Étude Anatomique et Chirugicale . Paris; Masson 1936
• 3 Salmon M. Artères des Muscles de la Tête et du Cou . Paris; Masson 1936
• 4 Salmon M, Taylor G I, Tempest M. Arteries of the Skin. New York; Churchill-Livingston 1988
• 5 Salmon M, Taylor G I, Razaboni R M. Arteries of the Muscles of the Extremities and the Trunk. St. Louis, MO; Quality Medical Publishing 1994
• 6 Taylor G I, Palmer J H. The vascular territories (angiosomes) of the body: experimental study and clinical applications.  Br J Plast Surg. 1987;  40 113-141
• 7 Houseman N D, Taylor G I, Pan W R. The angiosomes of the head and neck: anatomic study and clinical applications.  Plast Reconstr Surg. 2000;  105 2287-2313
• 8 Amethyst Galleries, Inc .Amethyst Galleries' Mineral Gallery. The Mineral Minium. Available at: http://mineral.galleries.com/minerals/oxides/minium/minium.htm. Accessed July 19, 2004
• 9 Amethyst Galleries, Inc .Amethyst Galleries' Mineral Gallery. The Mineral Massicot. Available at: http://mineral.galleries.com/minerals/oxides/massicot/massicot.htm. Accessed July 19, 2004
• 10 Rees M J, Taylor G I. A simplified lead oxide cadaver injection technique.  Plast Reconstr Surg. 1986;  77 141-145