Injectable Media

Barium Sulfate Mixtures These are probably the most widely used radiopaque media for vascular injection. Some dry-powder preparations are commercially available (Sigma B-3758, Sigma, P.O. Box 14508, St. Louis, MO). The barium sulfate usually is diluted with 10% formalin solution. In most instances, 5% gelatin is added to cause the mass to solidify after injection. The viscosity of the solution can be decreased by decreasing the amount of gelatin added or by adding more saline. Vessels as small as 30-60 pm in luminal width can be filled. The actual viscosity of the medium within the specimen depends on many variables, including the speed of injection and the temperature of the injected tissues. Therefore, each laboratory will have to standardize its own techniques. The injection often is done by quite elaborate methods, but, in our experience, injection by hand with a large glass syringe will give excellent results for routine examination and most qualitative studies.

We have used barium sulfate-gelatin mixtures to inject most organ-related vascular systems, the vessels of the lower extremities, the aorta and its branches, and the inferior vena cava system (see Chapters 3-6). For postmortem coronary angiography (see Chapter 12), we use gelatine mixtures, either with barium sulfate or with iothalamate-meglumine, as shown here:

Barium sulfate Iothalamate-meglumine mixture mixture

500 mL distilled water 500 mL distilled water

650 g barium sulfatea OR 100 mL iothalamate meglumine (Conray®)b 15 g gelatinec 15 g gelatinec

3 g thymold 3 g thymold a Barosperse® (Cat. no. 130108; NDC 59081-621-13), Lafayette Pharmaceutical, Inc., Lafayette, IN 47904.

bConray® (iothalamate meglumine injection U.S.P. 60%), Mallinckrodt Medical, Inc., St. Louis, MO 63042.

c Gelatin (laboratory grade, 275 bloom), Fisher Scientific, Fair Lawn, NJ 07410.

d Thymol (Cat. no. T185-100), Fisher Scientific, Fair Lawn, NJ 07410.

For the preparation of these mixtures, heat the distilled water to about 45°C in a beaker on a magnetic stir plate. Add the gelatine and let it stir until completely dissolved. Then add the contrast agent (barium sulfate or Conray), with thymol as a preservative to retard bacterial or fungal growth. Stir for approx 30 min until the solution is smooth. Divide the mixture into aliquots of 50-60 mL. These may be stored unrefrigerated in capped bottles for up to 1 yr.

In rare instances, staining of the injection mass may be required —for example, for differential display of the right and left coronary artery systems. For a setup of pressure- controlled injection in such a setting, see Chapter 12, Fig. 12-5. Barium sulfate with various pigment colors is commercially available (Sigma, see above). We have occasionally stained barium sulfate-gelatine mixtures with carmine, Berlin blue, naphthol green, or acri-dine yellow.

Media Containing Heavy Metals The media often contained lead or mercuric salts (9,10). Because of the toxic hazard, their use is no longer recommended.

Clinical Contrast Media These media (e.g., Ethiodol®, Savage Laboratories, 60 Baylis Road, Melville, NY 11747, or Sodium Diatrizoate from SIGMA, P.O. Box 14508, St. Louis, MO 63178-9916) are expensive and, when pure, are lost for histologic identification during processing. However, they are readily available in most hospitals and can be recommended for pathologists who do injection work only on occasion. As described earlier, we use an iothalamate-meglumine mixture for coronary arteriography. Coloring agents can be added to these media for macroscopic and microscopic identification.

India Ink This material is used primarily for microscopic study of the microvasculature. The black pigment stands out readily before and after histologic processing. India ink can be mixed with gelatine and water. Thick sections usually are studied. If these are to be studied microradiographically, a radiopaque mass such as diluted Chromopaque neutral medium is required.

Fig. 15-1. Vinyl plastic cast of normal kidney. Red, blue, and yellow plastic was used so that in the corrosion cast, arteries were red, veins blue, and pelvis with ureter, yellow.

Plastics Excellent casts of vessels and cavities can be prepared with vinyl-acetate plastic mixtures (Aldrich Chemical Co., Inc., 1001 West Saint Paul Ave., Milwaukee, WI, 53233), as shown in Fig. 15-1. Some of these have also been made radiopaque.

Metal Casts These are made of alloys with very low melting points such as Wood's metal. Bronchograms or casts of hydronephroses or cystic tumors can easily be prepared with this method. For tissue maceration, antiformin is suggested (see Chapter 8).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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