Splenorenal Shunt Blood Flow by Transit–Time Ultrasound As An Index of Collateral Circulation in Portal Hypertensive Rats

Abstract

The aim of this study was to develop a technique that could serve as an index of portosystemic shunt (PSS) blood flow in portal hypertensive rats whose main shunt is the splenorenal shunt (SRS). The main hemodynamic measurements performed were: SRS blood flow by the transit-time ultrasound (TTU) method, percentage of PSS, and regional blood flows by the microsphere method. We determined the accuracy and reproducibility of SRS blood flow measurements under baseline and pharmacological (octreotide) conditions. SRS blood flow was compared with other hemodynamic characteristics. Two models of portal hypertension were used: secondary biliary and dimethylnitrosamine cirrhosis. The SRS blood flow was correlated with mesenteric (r ‫؍‬ .76; P F .001) and splenic (r ‫؍‬ .67; P F .01) PSS percentages. The intra-and interobserver agreements for SRS blood flow were excellent: r ic ‫؍‬ .99 and r ic ‫؍‬ .98, respectively. SRS blood flow was six times higher in portal hypertensive rats (0.6 ؎ 0.7 mL · min ؊1 · 100 g ؊1 ) than in sham rats (0.1 ؎ 0.1 mL · min ؊1 · 100 g ؊1 [P F .01]). Octreotide significantly decreased SRS blood flow but not mesenteric or splenic PSS percentages. SRS is the main PSS in rats. The measurement of SRS blood flow by TTU is accurate and reproducible. This method can be used to identify new mechanisms in hemodynamic studies that differ from those identified by the measurement of the percentage of PSS by the microsphere method, especially in pharmacological studies. (HEPATOLOGY 1998;28:1269-1274.)Collateral venous circulation is the main consequence of portal hypertension (PHT). Until now, the effect of drug administration on the collateral circulation could not be measured in the same rat without using a sophisticated model. 1 Moreover, the percentage of portosystemic shunts (PSS) or the porto-collateral resistance could only be estimated. 2 It has recently been shown that portal tributary blood flow (PTBF) might be a driving force that is independent of portal pressure (PP) in the development of PSS, 3 thus emphasizing the importance of collateral blood flow. The main hemodynamic effect of some drugs such as somatostatin or its analogues involves collateral blood flow. 4 For these reasons, we developed a technique to measure collateral blood flow in rats in the same way as azygos blood flow is measured in humans.To evaluate the collateral blood flow in portal hypertensive rats, a technique was needed that measured blood flow in small vessels, and a vessel reflecting the collateral circulation had to be identified. The transit-time ultrasound (TTU) technique was used, a method that provides blood flow measurements with a perivascular flow probe in a specific vessel and has been already validated for arterial 5 and portal 6 blood flows in rats. The collateral circulation is mainly represented by the splenorenal shunt (SRS) in portal hypertensive rats. 7 The main aim of this study was to evaluate the accuracy and reproducibility of a new method to determine blood flow in collateral circulation in rats: t...

Hemodynamic effects of the early and long-term administration of propranolol in rats with intrahepatic portal hypertension

“…The preventive effect on the development of the collateral venous circulation predominates the action of vasomotor effect, because the low outflow values of SRS-BF, despite the development of hepatic fibrosis, strongly suggest an effect on the development of collateral circulation for two reasons: First, such dramatic hemodynamic data have never been observed in acute or chronic delayed administration, that is, when fibrosis or PHT was already acquired. Second, these values of SRS-BF are similar to that observed in baseline conditions in normal rats [20,21]. Moreover, the macroscopic aspect of SRS in treated rats was similar to normal rats.…”

“…The SRS is the main collecting vessel of the collateral circulation in portal hypertensive rats [23]. The determination of SRS-BF by TTU method was shown as an accurate index of collateral circulation, which was well correlated with the quantification of PSS by a microspheres method [20]. A TTU method appears more suitable than a microsphere method.…”

“…In PHT rats, the main PSS is the splenorenal shunt (SRS), while the collateral esophageal venous network is poorly developed [20]. Measurement of SRS blood flow (SRS-BF) was performed by using a transit-time ultrasound (TTU) technique, which consists of a volumetric blood measurement flow using a perivascular flow probe.…”

Hemodynamic Assessment of the Development of Portal-Systemic Collaterals in Portal Hypertensive Rats

“…The changes of portal pressure and the flow and diameter of SRS were determined at 1, 4, 7, 10, and 14 days after ligation surgery (n = 6, 6, 6, 7, and 9 in each PVL group, respectively) or sham operation (n = 6, 6, 6, 4, and 8 in each sham group, respectively). The portal pressure was measured by the catheterization method and subsequently the SRS flow was detected by transit-time ultrasound (TTU) in individual rats at the scheduled day [14]. The resistance of SRS (R-SRS) was calculated from SRS flow and portal pressure.…”

“…It drains portal blood flow into inferior vena cava via left renal vein [11][12][13]. It was reported that the SRS flow may reflect the flow of portal-systemic collaterals [14,15]. In well-established portal hypertensive rats, SRS flow positively correlated with portal pressure and the extent of hepatic fibrosis [15].…”