Small vessels study using a radiopaque dye

Hanania, Fábio Richieri; Iamaguchi, Maurício Masasi; Rezende, Marcelo Rosa de

doi:10.1590/S1413-78522002000300001

Abstracts

The purpose of our research consists of studying a new dye which, besides allowing the macroscopic study of small vessels ¾ following the pioneer research of Salmon(3) ¾, permits the radiographic study due to its radiopacity. To do so, ten rats were utilized and their abdominal aorta was catheterized for the injection of the dye towards the periphery, being the flow of the dye observed along the left femoral artery (the right one was cauterized for occlusion). The results of this injection revealed that the dye penetrates well in extremely small vessels and allows dissection without extravasations. Thus, we believe that this dye has the necessary requirements for the study of details of the vascular anatomy.

Dye; vascular; anatomy

A proposta do nosso trabalho consiste no estudo de um novo corante que, além de permitir o estudo macroscópico de pequenos vasos ¾ seguindo a pesquisa pioneira de Salmon(3) ¾, possibilita o estudo radiológico por ser uma solução radiopaca. Para tanto foram utilizados 10 ratos e cateterizadas suas aortas abdominais para a injeção do corante no sentido da periferia, acompanhando o seu fluxo pela artéria femoral esquerda (a direita foi cauterizada). Os resultados de sua utilização na artéria femoral de rato mostraram tratar-se de uma solução com boa capacidade de penetração em vasos extremamente pequenos e que permite a dissecção sem que haja extravasamento do corante. Tendo em vista os resultados obtidos em ratos, acreditamos que o corante reúne os quesitos necessários para o estudo de detalhes da anatomia vascular.

Corante; vascular; anatomia

Small vessels study using a radiopaque dye

Estudo anatômico de pequenos vasos com corante radiopaco

Fábio Richieri Hanania^I; Maurício Masasi Iamaguchi^II; Marcelo Rosa de Rezende^III

^I4^th. year student, Faculdade de Medicina da Universidade de São Paulo

^II4^th. year student, Faculdade de Medicina da Universidade de São Paulo

^IIIMaster/Chairman, Faculdade de Medicina da Universidade de São Paulo

Address for correspondence

SUMMARY

The purpose of our research consists of studying a new dye which, besides allowing the macroscopic study of small vessels ¾ following the pioneer research of Salmon⁽³⁾¾, permits the radiographic study due to its radiopacity. To do so, ten rats were utilized and their abdominal aorta was catheterized for the injection of the dye towards the periphery, being the flow of the dye observed along the left femoral artery (the right one was cauterized for occlusion). The results of this injection revealed that the dye penetrates well in extremely small vessels and allows dissection without extravasations. Thus, we believe that this dye has the necessary requirements for the study of details of the vascular anatomy.

Key words: Dye; vascular; anatomy

RESUMO

A proposta do nosso trabalho consiste no estudo de um novo corante que, além de permitir o estudo macroscópico de pequenos vasos ¾ seguindo a pesquisa pioneira de Salmon⁽³⁾¾, possibilita o estudo radiológico por ser uma solução radiopaca. Para tanto foram utilizados 10 ratos e cateterizadas suas aortas abdominais para a injeção do corante no sentido da periferia, acompanhando o seu fluxo pela artéria femoral esquerda (a direita foi cauterizada). Os resultados de sua utilização na artéria femoral de rato mostraram tratar-se de uma solução com boa capacidade de penetração em vasos extremamente pequenos e que permite a dissecção sem que haja extravasamento do corante. Tendo em vista os resultados obtidos em ratos, acreditamos que o corante reúne os quesitos necessários para o estudo de detalhes da anatomia vascular.

Palavras-chave: Corante; vascular; anatomia

INTRODUCTION

The study of details of vascular anatomy demands the use of dyes which, among other qualities, have also good penetration, allow a good visualization, are radiopaque (allowing radiological study) and can present solidification, in order not to prevent dye leaking.

The use of dye and contrasts for vascular anatomical studies was pioneered by Salmon⁽³⁾, what lead to great advance in studies on body blood vessels. Later, the preparation by Salmon⁽³⁾ was modified by Rees and Taylor⁽²⁾ using in their experiment lead oxide for contrast, however never combining both dye and contrast in a same mixture. Peden, Robinson and Rohrich⁽¹⁾ succeeded in doing so; however, the difficulty to access dye components makes difficult and expensive its preparation in Brazil.

The difficulties above mentioned, as high cost and difficult access to dyes, motivated us to develop a new dye. Thus, we prepared a low cost solution with easily accessible components (due to commercial and industrial use).

MATERIALS AND METHODS

Dye

The studied product was prepared with the following substances: pure acetone (100%), powder lead oxide (Letargirio®), vinil gum (Vinilitâ), blue thinner based ink.

All components of the dye are of industrial use, so, easy to purchase. It is initially prepared as a solution without lead oxide, being however imperative to have 40% of acetone to warrant the necessary fluidity. The solution was not mixed to lead oxide before the preparation of the rat, because acetone is very much volatile and the mixture easily forms sediment, what would alter dye composition during the time of the procedure.

Materials

For this method were used: the above mentioned dye, 10 rats, a catheter of 0.7 x 19 mm, anatomical forceps, jeweler forceps, scalpel, a microsurgery microscope, photograph machine and others.

Rats

The used rats were of Wistar strain, weighting approximately 250 g and obtained from the Rotary Reconstructive Microsurgery Lab. from the Centro de Treinamento do IOT-FMUSP (Instituto de Ortopedia e Traumatologia ¾ Faculdade de Medicina da Universidade de São Paulo), where the study was performed.

Radiography

For the radiographic examinations it was used an equipment Toshiba, with the following specifications: Focus=100, Kv=35 e Time=0,03s.

Method

In order to test the qualities of the dye it was chosen a place of observation of the vessels. Were studied the abdominal aorta, the caudal artery, the common iliac arteries and their branches, mainly the ventral part of the posterior rat limb after the trifurcation of the femoral artery into anterior tibial, posterior tibial and fibular arteries.

Beginning, the abdominal wall of the rat was retracted in order to expose its viscera which were retracted leftwards, exposing the inferior cava vein, the abdominal aorta and the common iliac arteries.

The common right iliac artery was dissected for later binding. The aorta was dissected as well for later binding (of the proximal portion of catheterization) and the abdominal part catheterized.

A catheter of 0.7 x 19 mm was introduced into aorta towards periphery. An incision at the ventral aspect of posterior limb was performed in order to expose its arteries. It was injected through the catheter 1 ml of saline solution for cleaning of the vessels. Only at this moment the dye (with 40% of acetone) was mixed to lead oxide in a recipient with a stick in a proportion of 6/1 (six parts of dye for one par of lead oxide). After mixing well, it was injected through the catheter a small amount of the mixture (about 1 ml), carefully avoiding to inject air bubbles into the circulation, since this would prejudice viewing the vessels and would cause higher resistance to perfusion by the dye. The posterior limb arteries could then be observed (fig.1).

After a period of about 5 minutes the dye hardens, however does not becomes brittle ¾ remains flexible, with a plastic aspect (fig. 2 ¾ the wall of distal portion of the aorta and the proximal portions of common iliac arteries were removed, demonstrating that the dye hardens, molding the inner face of the vessels). From this, radiographs were taken of the posterior limb of the rat (fig. 3) demonstrating the vessels with high precision, and their arteries were after dissected for better observation.

Due precautions were taken in order to avoid lead intoxication, such as the use of gloves and masks during the procedure.

RESULTS

The dye proven to be fluid enough to reach the artery of the tail of the rat, and extremely thin branches of arteries of the posterior limb. After about five minutes, the dye reaches a viscous consistency, allowing dissection without leaking to adjacent tissues. It is also worthy to notice the excellent radiographic contrast obtained with PbO, allowing an accurate observation of the vessels in the radiographs (fig 4 ¾ detail of a small vessel the dye entered in).

DISCUSSION

With arrival of Vascular Microsurgery in the sixties, a significant increase in the interest on study of details of several parts of human body circulation emerged, making extremely important the study of vascular anatomy in cadavers. Most of the marketed dyes are not suitable for this study due to weak staining or due to not allowing the radiological study of the vessels. With our dye, we looked for an association of both characteristics, based on the experiments by Salmon⁽³⁾. We obtained a dye with intensive staining, which allowed the radiographic observation of vessels as thin as 0,1 mm. Additionally, there is a national difficulty in obtaining already existing contrasts, whether because they are hardly accessible in our local market, or due to an excessive cost; thus, we looked for eliminating these difficulties, as well as to develop a dye easy do prepare. So, we believe that our solution fulfills all necessary specifications to be considered a good dye for the study of human vascular anatomy.

CONCLUSION

The necessary qualities were reached. The preparation was demonstrated to be easy to inject, allowing a good observation both for photographs and radiographs, besides of penetrating the thinner vessels (diameters up to ~ 0.1 mm). Besides this, it is important to notice its low cost, allowing the use of this dye in a very efficacious way for studying the human vascular anatomy.

FINAL REMARKS

- We create for this project no boards, tables, illustrations or diagrams. It consists only of text and photographs.

- No animal was sacrificed solely for the purpose of performing this study. Instead, animals just sacrificed by trainees from the Rotary Reconstructive Microsurgery Lab. of the IOT-FMUSP, which would be discharged, were used.

- The lab, represented by the instructor Dr. Marcelo Rosa de Rezende, approved and encouraged this study to be performed.

Address for correspondence

Rua Rocinha, 22, Saúde

CEP: 04127-030 São Paulo, SP

Email: fabio_rh@yahoo.com.br

Trabalho recebido em 21/12/2001. Aprovado em 17/05/2002

Work performed at Rotary Microsurgery Lab. from Training Center of IOT do Hospital das Clínicas - FMUS

1. Peden, E.K., Robinson, J.B. Jr., Rohrich, R.J.: An improved injection system for vascular anatomical studies having dual radiopacity and visualization capabilities. Ann Plast Surg 32(4): 407-410, 1994.
2. Rees, M.J., Taylor, G.I.: A simplified lead oxide cadaver injection technique. Plast Reconstr Surg 77: 141-145, 1986.
3. Salmon, M.: Artères de la peau: étude anatomique et chirurgicale, Paris, Masson, 1936.