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HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



to interfere with perfusability. As noted above, the 

 injection of colored plastic semisolid substances aids 

 in defining functional relationships between vascular 

 structures as well as their anatomic arrangements. 

 The extent to which streams of different color inter- 

 mingle or fill a given portion of the vascular bed 

 points to dynamic relations that may be important 

 in life. 



Radiopaque injection masses have been used in 

 both living and "dead - ' livers in order to visualize 

 the vascular tree by X ray (22, 84, 148). Daniel & 

 Prichard (102) have used microangiography to 

 study portal venous flow in rats, cats, guinea pigs, 

 rabbits, and goats. Contrast substance is injected 

 rapidly into an omental or intestinal vein and serial 

 radiographs taken thereafter at a rate of one or two 

 per sec over a 9- to 1 2-sec period or motion pictures by 

 high-speed cinefluorography (144). The dispersion 

 of the radiopaque material in the blood stream, the 

 distribution of portal inflow to the hepatic segments, 

 and the time of blood movement may be determined 

 graphically in this manner. Although there are ob- 

 vious drawbacks (anesthesia, immobilization, the 

 presence of a foreign material in very high concen- 

 tration, and manipulation of the gut), certain hemo- 

 dynamic effects can be examined only by this method. 



Radiographic methods of studying the portal 

 venous system have also proved of value diagnosti- 

 cally. Roentgenograms taken at the operating table 

 immediately after injection of a concentrated solution 

 of Diodrast (85) (70% — 12 to 40 ml, depending on 

 the size of the patient) or Urokon (70% — in similar 

 dosage) into a tributary of the portal vein have been 

 helpful in determining the extent of collateral cir- 

 culation or the point of venous obstruction in patients 

 with portal venous hypertension. Percutaneous 

 splenoportal venography (15, 314) permits visualiza- 

 tion of the splenic and portal veins in anesthetized 

 patients and, when rapid serial radiography is em- 

 ployed, the character of blood flow and vascular 

 filling can be made out. Diodrast or Urokon may be 

 injected directly into the spleen through a long 17- 

 or 18-gauge needle that is inserted through the skin 

 under local anesthesia. In most patients, subjected 

 to this procedure, the spleen is palpable and the 

 needle may be placed obliquely into the body of the 

 spleen, or it may be introduced through the ninth 

 intercostal space at the midaxillary or posterior 

 axillary line. The contrast substance leaves the spleen 

 almost at once and may be detected radiographically 

 within one or two seconds in the portal vein and its 

 branches. The procedure is somewhat hazardous, 



since intraperitoneal bleeding often occurs and 

 splenic infarcts may develop. Severe hemorrhage has 

 been reported. 



Of even greater potential danger is a new variant 

 of the technique of splenoportal venography de- 

 scribed by Bierman and his associates (32), who 

 introduce a needle through the liver into the portal 

 vein. However, they report that no serious complica- 

 tions developed following or in the course of 1 44 

 transhepatic portal venipunctures in 73 seriously 

 ill patients. Under local anesthesia, while the patient 

 holds his breath, they insert a special large-gauge 

 styletted needle at a point 1 cm below the xiphoid 

 process and 1 cm to the right of the midline to a depth 

 of 12 cm. The obturator is then removed and the 

 needle is slowly withdrawn during application of 

 gentle suction until there is free flow of blood, indi- 

 cating that the laterally placed orifice lies in a vessel. 

 A small ureteral catheter or polyethylene tubing 

 may be threaded through the needle into the vein 

 and left in place for a prolonged period after the 

 needle has been withdrawn. A contrast medium 

 such as Diodrast, Urokon, or Neo-Iopax (sodium 

 acetrizoate, iodopyracet, or sodium iodomethamate) 

 may be injected through the needle or catheter. 

 In a number of instances, the hepatic vein, inferior 

 vena cava, or hepatic artery have been visualized. 

 Zeid ft al. (314) have had a similar experience. A 

 more recent development which employs the costal 

 intra-osseous route appears to be considerably safer 

 (262). The injection of contrast material directly 

 into the medullary cavity of a lower rib results in 

 visualization of veins in the vertebral, intercostal, 

 azygos, and hemiazygos drainage system. In con- 

 tradistinction to splenoportal venography, which 

 reveals portal collateral channels in the presence of 

 portal hypertension, intraosseous venography permits 

 detection of systemic venous collaterals. 



HEPATIC AND SPLANCHNIC BLOOD VOLUMES. The vol- 

 ume of blood in the liver and the splanchnic bed 

 may also be estimated by radiographic and injection 

 techniques. The relative mass of the hepatic vascula- 

 ture has been evaluated qualitatively from veno- 

 grams and arteriograms, and from the volume of 

 plastic casts of vascular tree. Measurement of the 

 liver opacified by contrast medium or delineated 

 after inflation of the stomach or colon with gas is also 

 theoretically possible (300). Changes in the size of 

 the spleen have been followed radiographically 

 (20) and interpreted in terms of displacement or 

 filling with blood. Unfortunately, the extent of vascu- 



