The Effect of a Side-to-Side Portacaval Shunt on Hepatic Hemodynamics in Cirrhosis*

Abstract

Since various types of surgical portal-systemic venous anastomoses are employed in the treatment of portal hypertension, it is of interest to know the effect of these operations on hepatic hemodynamics.There is general agreement that the major hepatic hemodynamic disturbance in cirrhosis is an increase in vascular resistance in the liver, together with an increase in portal venous pressure, and a variable, moderate reduction in hepatic venous blood flow. The fact that wedged hepatic vein pressure is increased to near portal vein pressure level in most patients suggests that the major portion of the increased vascular resistance is on the hepatic venous side of the sinusoid. Portal hypertension, then, can be regarded as a compensatory mechanism for the increased vascular resistance caused by the cirrhotic liver. The possible contribution of increased splanchnic or hepatic arterial inflow to portal hypertension cannot be ignored, although if this were a major factor we would expect to find consistent increases in hepatic venous flow in cirrhosis. Creation of a surgical portal-systemic venous anastomosis would be expected to lower portal pressure and reduce portal inflow into the liver. The effect upon hepatic venous flow would be dependent upon the degree of reduction in portal venous inflow that existed prior to surgery, together with any adjustments that might take place in hepatic arterial flow.Bradley, Smythe, Fitzpatrick and Blakemore, using the standard sulfobromophthalein (BSP) method to measure liver blood flow, found an average fall of 22 per cent in five patients after *

Assessment of Portal and Hepatic Hemodynamics after Side-to-Side Portacaval Shunt in Patients with Cirrhosis*

“…Studies at the time of portacaval shunt by our surgical colleagues, Mikkelsen, Turrill, and Pattison, also indicated less extraction of oxygen and BSP from backflowing portal blood than from hepatic venous blood (10). Our catheterization data suggest a greater decrease in hepatic oxygen uptake after SS shunt than after ES shunt (8). After the oxygen and BSP samples had been obtained, the catheter was again passed into the wedged portal position to repeat the measurement of wedged portal pressure and to confirm the wedged position by the injection through the catheter of 3 to 4 ml of 50%o Hy It fell in all instances after opening the shunt, averaging then 22 cm saline.…”

“…In hepatic venous catheterization studies before and after SS shunt, we found a fall in splanchnic oxygen consumption from a mean of 52 ml per minute to a mean of 32 ml per minute (8). Al If our interpretation of our observations is correct, there should be little difference between the hemodynamic effects of SS and ES shunt in most patients.…”

“…Probably their patients were not a representative sample, since in preoperative pressure measurements by our surgical colleagues, evidence for reversed flow was found in only 7 of 61 patients (10). We have consistently (18 of 19 patients) found falls in hepatic blood flow after portacaval shunt, suggesting that portal blood does flow into the liver in most patients with cirrhosis (8,12). From our data the functional contribution of the blood leaving the liver in the portal vein appears quite variable.…”

“…The patient with the largest backflow measurement (R.R., 1,110 ml per minute) actually had definite forward flow at the time of the postoperative catheterization. It is interesting to compare the average value for potential backflow obtained in the patients in this study with the previously reported falls in hepatic blood flow (HBF) seen after ES and SS shunt (8,12). Mean preoperative HBF in 19 patients undergoing portacaval shunt was 1,439 ml per minute with no significant difference between the ES patients (1,493 ml per minute) and the SS patients (1,380 ml per minute).…”

“…The average differences between arterial and portal venous levels of BSP and oxygen were 0.33 mg per 100 ml and 20.1% saturation, respectively. For comparison, the differences between arterial and hepatic venous levels of these same substances in a comparable series of SS shunt patients were 0.67 mg per 100 ml and 42% saturation (8). In the single direct comparison that we made (patient M.M.…”