DROP IN THE BLOOD FLOW VELOCITY IN THE PORTAL VEIN SYSTEM AS A SIGN OF PORTAL HYPERTENSION Liver and biliary tract
Jetra i bilijarni trakt

ARCH GASTROENTEROHEPATOL 2001; 20 ( No 3- 4 ):

Drop of the portal blood flow velocity: An important sign  of the portal hypertension

Smanjenje brzine toka krvi u portnom sistemu: Znacajan znak u portnoj hipertenziji

( accepted December 30th, 2001 )

Dragan Tomić, Rada Ješić, Miodrag Krstić, Goran Janković, Aleksandra Pavlović, Vladislava Bulat, Tatjana Cvejić

Institute of  Digestive Diseases, Clinic for Gastroenterology and Hepatology, Clinical Centre of Serbia, Belgrade

Address correspondence to: Professor Dr Dragan Tomić

Hadži Ruvimova 5

11000 Beograd,

FAX: + 381 11  361 55 87

E-mail: daga@infosky.net
 

ABSTRACT

The aim of this study was to evaluate the diagnostic value of portal blood flow velocity decrease as an important sign of the portal hypertension. The study included 60 patients, aged 53 on average, with established portal hypertension based on the presence of oesophageal varices (mainly of the 2nd and 3rd degree). The control group included 55 clinically healthy subjects, aged 39 on average. Blood flow velocity in portal and splenic veins was measured by the use of a colour and pulsed Doppler. Portal blood flow velocity in patients with portal hypertension was 9.38 cm/s in portal vein, and 10.17 cm/s in splenic vein. In the constrols this was 17.66 cm/s in portal vein,  and 17.26 cm/s in splenic vein. These data clearly demonstratate that decnease of the portal blood flow velocity below 12cm/s is a reliable indicator of the portal hypertension.

Key words: Portal vein, blod velocity, portal hypertension.

SAŽETAK

Cilj istraživanja bio je da se utvrdi dijagnostička vrednost pada brzine toka krvi u portnom sistemu kao pokazatelja portne hipertenzije. Istraživanje je sprovedeno na 60 bolesnika, prosečne starosti 53 godine,  kod kojih je portna hipertenzija utvrđena  prisustvom variksa jednjaka (pretežno II i III stepena). Kontrolna grupa je obuhvatila  55 ispitanika klinički zdravih, prosečne starosti 39 godina. Brzina krvi u portnoj i lijenalnoj veni bolesnika i zdravih osoba, izmerena je tehnikom kolor i pulsnog doplera. Srednja vrednost brzine krvi u portnoj veni bolesnika sa portnom hipertenzijom, iznosila je 9.38 cm/s, odnosno 10.17 cm/s u lijenalnoj veni. Srednja vrednost brzine krvi u portnoj veni kontrolne grupe zdravih, bila je 17.66 cm/s i 17.26 cm/s u lijenalnoj veni. Evidentna statistička značajnost razlika dobijenih rezultata jasno je ukazala da se pad brzine krvi u venama portnog sistema može smatrati pouzdanim pokazateljem portne hipertenzije. Vredosti brzine krvi u portnoj i lijenalnoj veni mogu se smatrati patološkim odnosno sniženim, ukoliko su manje od 12 cm/s.

Ključne reči: Portna vena, brzina toka krvi, portna hipertenzija.

INTRODUCTION

There are several different methods which are sensitive indicators of the  portal blood velocity changes, e.g. portal hypertension in particular. Beside angiography, portal venous system color Doppler ultrasonography is an important technique for the assessment of the abnormalities in the portal circulation. This non-invasive and very sensitive technique which do not neccesitate hospitalisation and care no morbidity.

Portal blood flow velocity in different conditions is important to study. Decrease of bloow flow velocity is a reliable and sensitive diagnostic criterium of the portal hypertension. We therefore performed a study to evaluate whether drop of the portal blood flow velocity is a reliable diagnostic criterium of portal hypertension. Another aim of this study was to explore the possibility that the basic parameters of the portal blood flow can be reliably measured without lieno-mesenteric-portal angiography.
 
 

PATIENTS AND TEST METHODS

Test samples  This study included two group of patients. The first group was  composed of healthy persons, while the second group included patients with portal hypertension.

The patient, s group  included 60 cases, aged 53 on average, with portal hypertension diagnosed on the basis of the presence of esophageal varices (mainly of the 2nd and 3rd degree). The most common aetiology of portal hypertension was alcoholic liver cirrhosis (32 cases). Thirteen patients had posthepatitic cirrhosis. Four female patients had primary billiary cirrhosis, while 1 patient had primary sclerosing cholangitis. Regarding disease severity the majority were classified into the group B according to Child-Turcotte classification. A smaller number were group C according to the same classification.

The control group included 55 healthy individuals, aged 39 on average. This cases were referred for an ultrasonographic examination because of complaints that was proved to be of functional origin.

Parameter examined

Noninvasive measuring of the blood flow velocity in the portal and splenic veins was carried out in both groups.

Test conditions and method

Two test methods were used: ultrasonography with pulsed and colour Doppler and oesophagogastroduodenoscopy.

In order to detect oesophageal varices all patients suspected as having portal hypertension undergone upper GI endoscopy. Oesophageal varices were are classified into four grades,  from 1 to 4 according to Paquet ( 2 ). The biggest number of  patients with portal hypertension had varices of the grade 2 and 3.

In this study abdominal ultrasonography with pulsed and colour Doppler were used to study basic circulatory parameters of the portal system (3,4,5,6,7,8). Patients with varices and controls were examined with modern ultrasound units equipped with a pulsed and colour Doppler. The patients were examined at the Ultrasound Diagnostics Section of the Gastroenterological and Hepatological Clinic of the Clinical Centre of Serbia. The examination of the patients was made in the supine position, with an empty stomach, using a lot of transversal, longitudinal and oblique cross sections, and applying the so-called real time method. When the blood flow in the portal and splenic veins was visualised with colour Doppler and the pulsed Doppler, blood flow velocity was measured and calculated (9,10).

A classical ultrasound image is shown on the monitor where the segments of blood vessels the examiner is interested in, are coloured by the colour Doppler technique. By the pulsed Doppler technique, the examiner directs the narrow Doppler beam toward coloured segment of the blood vessel and outlines the scan line along which he can analyze the blood flow velocity.  The analysis is made on the scan line which is marked with a special marker, a Doppler window. Its position in relation to the blood vessel is also determined by the examiner. Figure 1. An ideal conditions is when  Doppler beam is parallel with the longitudinal axis of the blood vessel. In  practice, the most common situation is when Doppler beam makes sharp angle of some degree in relation with the blood vessel axis. An angle of 60o is considered as upper limit when measurement is possible.

A graphic velocity spectrum is shown in a part of the monitor. These speed values are established in the area designated by the Doppler window. The time base is on the projected graph on x-axis while the ordinate y-axis is the velocity function. It is taken arbitrarily that the flow direction towards the probe be considered positive and it is brought over the positive part of the ordinate. The opposite direction (leading away from the probe) is considered as negative and it corresponds to the negative part of the ordinate on the graph, and it is shown under the x-axis.

The described method of examination makes possible to determine precisely the velocity or more precisely the distribution of the blood flow velocity values in the blood vessel at selected places. The numerical values of the blood flow velocity are shown automatically on the graph ordinate. The blood flow direction is determined in relation to the x-axis of the shown speed spectrum.

For all the values of the blood flow speed in the portal and splenic veins of the patients and the healthy controls we claclulated the arithemetic mean (X), standard deviation (SD), variation coefficient (V%), the maximum result (Max), the minimal result (Min) and the result range (R). The significance of the differences in the arithmetic mean of the blood flow speed with patients and healthy examinees was assessed by the calculation of the t-test. Starting from the values of both samples (N=60 and N=55), the difference in arithemetic mean values is statistically significant if the t-test value is equal or higher than the critical level of 1.98 (with the reliability of making a conclusion of 0.95).

RESULTS

In patients with portal hypertension, the average portal blood flow velocity was 9.38 cm/s; in the control group 17.66 cm/s. This difference was statistically significant (t>t 0,001). Table 1, 2 .

The average blood flow velocity in the splenic vein in the patients with portal hypertension was 10.17 cm/s; in the control group 17.26 cm/s. This difference was statistically (t>t 0,001) as well. Table 3.

DISCUSSION

At present, noninvasive measurements of the portal flow velocity, especially by pulsed and colour Doppler became an important technique to study  portal venous system haemodynamics. The reliability of pulsed and colour Doppler method in establishing intravascular blood flow velocity was emphesised by many authors (11,12,13,14). When compared with invasive methods, primarily CT angiographic procedures, the reliability of results obtained by pulsed and coulor Doppler techique was high.

Several authors studied normal portal venous system haemodynamics by pulsed and colour Doppler technique. Zoli is his study of 82 patients, reported an average value of the portal vein blood flow velocity of 10.5 cm/s, and 16 cm/s in healthy individuals (17). According to Zironi, the average value of the portal vein blood flow velocity in healthy persons  was 19.6 cm/s, while in patients with portal hypertension this was 13 cm/s  (18). In this study we found an average value of the portal blood flow velocity in healthy controls 17.66 cm/s, range: 15-23 cm/s (15). Adding or deducting two standard deviations (which includes 95.5% of the examinees) this gives a range of 14.36-20.96 cm/s. In adition we found an average splenic vein blood flow velocity in healthy controls 17.26 cm/s, range: 15-23 cm/s. Adding or deducting two standard deviations (including 95,5% of the examinees) this gives a range of 13.46-21.06 cm/s.

Takayoshi, Saito, Shiraki, and Chawla demonstrated that in patients with portal hypertension of various aetiology, there is a considerable drop of  the portal, splenic, and upper mesenteric vein blood flow velocity (16,19,20,21,22). According to this study and numerous other reports portal blood  flow velocity decrease in the portal and splenic veins is a reliable ultrasonographic sign of portal hypertension (23,24).

In this study we demonstrated that average blood flow velocity in the portal vein in patients with portal hypertension was 9.38 cm/s, range: 6-13 cm/s. Figure 2. Adding and deducting two standard deviations (which includes 95.5% of the patients) this gives a range of 6.54-12.22 cm/s. As values of portal hypertensive patients were lower than in healthy examinees, it was important to define the cutt-off value of the blood flow velocity between patients and healthy controls. This was 12 cm/s. Consequently abnormal values of the portal blood flow velocities in portal hypertension is <12 cm/s More profound drop in the portal vein blood flow velocity is encountered in a cases with portal vein trombosis or in its main branches (29,30,31).

The flow pattern in the splenic vein in patients with portal hypertension has been previously studed. Using Doppler ultrasound, Barakat describes the intrasplenic venous flow direction in 176 adult patients with intrahepatic portal hypertension (35). In this study we found an average value of the blod flow velocity in the splenic vein in portal hypertension is 10.17 cm/s, range: 7-12 cm/s. Figure 3.  When two standard deviations are added and deducted (which includes 95.5% of the patients sample group), this give a range 7.61-12.3 cm/s. The upper reference value is 12 cm/s, which means that all higher values are normal, and lower < 12 cm/s indicate portal hypertension.

Gastric mucosal blood in portal gastropathy manifested with GI bleeding is studied by several authors as well (25,26). Iwao demonstrated by laser Doppler technique very slow, slugish gastric mucosal blood flow velocity in patients with portal hypertension and hypertensive gastropathy (27,28).

In portal hypertension, portal blood flow velocity measurements may predict the risk of variceal bleeding. It is demonstrated by echo-Doppler flowmetry that in liver cirrhosis there is an insiginficant rise of postprandial portal blood flow. Postprandial rise of portal flow velocity is inversely related to the severity of portal hypertension in liver cirrhosis, and this appears to be  valuable indicator of an increased risk of variceal bleeding (32). In Cioni's study it was shown that variations in portal vein Doppler sonographic parameters induced by administration of  beta-blocker may predict long-term effects of these drugs in the prevention of a first episode of variceal bleeding (33). In addition, significantly lower portal flow velocity was observed in patients of fulminant hepatic failure with ascites compared with those without ascites (34).

The usefulness of color Doppler sonography in the detection of spontaneous portosystemic shunts and abnormal blood flow direction in the portal vein in patients with cirrhosis, were evaluated also. Portosystemic shunts and the direction and velocity of portal venous flow are important features in the sonographic diagnosis of portal hypertension (36).

  This tehnique can be applied for arterial flow velocity measurement too. Kito, prospectively measured the flow velocity and resistive index of the common, right, and left hepatic arteries, using Doppler sonography, in 21 patients who underwent embolization of the right portal vein. Portal vein embolization induces an increase in hepatic arterial blood flow velocity in the embolized hepatic segments, resulting from an increase in common hepatic arterial flow. This observation may be explained by the simple mechanical effect of interposing a slower flowing stream (portal flow) in the path of a faster flowing stream (arterial flow)(37).
 
 

                 Using color Doppler and pulsed Doppler ultrasound, blood flow changes inside normally functioning transjugular intrahepatic portosystemic shunts (TIPS) can be evaluated. A velocity gradient between the portal and the venous side of a TIPS is a normal finding caused by branches of the portal and hepatic vein joining the TIPS from the side and it is characteristic of a normally functioning TIPS (38).

In conclusion, pulsed and colour Doppler technique are an important tool for qantitative measurements and assessment of hemodynamic parameters of the portal circulation in varienty of contidions, especially portal hypertension. The colour and pulsed Doppler method is of comparable sensitivity and preciseness with other invasive methods in assessing patients with suspected portal hypertansion.  Direct visualisation of the blood flow and their parameters measurements considerably shortens the examination time (39,40).

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12. Lomas DJ, Britton PD, Summerton CB, Seymour CA. Duplex Doppler measurements of the portal vein in portal hypertension. Clin Radiol 1993; 48: 311-5.

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15: Rehrer NJ, Smets A, Reynaert H, Goes E, De Meirleir K. Effect of exercise on portal vein blood flow in man. Med Sci Sports Exerc 2001; 33: 1533-7

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17. Zoli M, Marchesini G, Cordiani MR, et al. Echo-Doppler measurement of splanchnic blood flow in control and cirrhotic subjects. J Clin Ultrasound 1986; 14: 429-35.

18. Zironi G, Gaiani S, Fenyves D, Rigamonti A, Bolondi L, Barbara l. Velue of measurement of mean portal flow velocity by Doppler flowmetry in the diagnosis of portal hypertension. J Hepatol 1992; 16: 298-303.

19. Tanabe T, Tobe K, Koide N, et al. Blood flow dynamics in the portal venous system in the liver diseases studied by the ultrasonic pulsed Doppler method. Acta Hepatologica Japonica 1985; 26: 65-73.

20. Saito M, Erabayashi H, Wada K, et al. Ultrasonic measurement of portal and splenic venous flow and their velocities in normal subjects and patients with chronic liver disease. Acta Hepatologica Japonica 1984; 25: 1281-87.

21. Shiraci S, Tsucada K, Ozeki N, et al. Measurement of portal blood flow by an ultrasonic duplex system composed of a pulsed Doppler flowmeter and a linear-type real time B mode electroscanner. Gastroenterol Jap 1988; 23: 37-43.

22: Chawla Y, Sreedharan A, Dhiman RK, Jain S, Suri S. Portal hemodynamics in fulminant hepatic failure as assessed by duplex Doppler ultrasonography. Dig Dis Sci 2001; 46: 504-8

23: Yin XY, Lu MD, Huang JF, Xie XY, Liang LJ. Color Doppler velocity profile assessment of portal hemodynamics in cirrhotic patients with portal hypertension: correlation with esophageal variceal bleeding. J Clin Ultrasound 2001; 29:7-13

24: Erdozain Sosa JC, Martin Hervas C, Moreno Blanco MA, et al. Color duplex Doppler ultrasonography in the evaluation of the risk of esophageal varices bleeding in cirrhotic patients. Gastroenterol Hepatol 2000; 23:466-9

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28: Gupta R, Sawant P, Parameshwar RV, Lele VR, Kulhalli PM, Mahajani SS. Gastric mucosal blood flow and hepatic perfusion index in patients with portal hypertensive gastropathy. J Gastroenterol Hepatol 1998; 13:921-6

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31: Malkan GH, Bhatia SJ, Bashir K, et al. Cholangiopathy associated with portal hypertension: diagnostic evaluation and clinical implications. Gastrointest Endosc   1999; 49:344-8

32: Ludwig D, Schwarting K, Korbel CM, Bruning A, Schiefer B, Stange EF. The postprandial portal flow is related to the severity of portal hypertension and liver cirrhosis. J Hepatol 1998; 28:631-8

33: Cioni G, Turrini F, Tincani E, et al. Prevention of a first episode of variceal bleeding: role of duplex Doppler sonographic measurement of the acute response to beta-blockers. J Ultrasound Med 1999; 18: 633-8

34: Chawla Y, Sreedharan A, Dhiman RK, Jain S, Suri S. Portal hemodynamics in fulminant hepatic failure as assessed by duplex Doppler ultrasonography. Dig Dis Sci 2001; 46: 504-8

35: Barakat M, Hassan A, Soliman A, Nafeh M. Intrasplenic venous flow patterns demonstrated by Doppler ultrasound in patients with portal hypertension. Br J Radiol 1998; 71: 384-7

36: von Herbay A, Frieling T, Haussinger D.J. Color Doppler sonographic evaluation of spontaneous portosystemic shunts and inversion of portal venous flow in patients with cirrhosis. Clin Ultrasound 2000; 28: 332-9

37: Kito Y, Nagino M, Nimura Y. Doppler sonography of hepatic arterial blood flow velocity after percutaneous transhepatic portal vein embolization. AJR Am J Roentgenol 2001; 176:909-12

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39. Mostbeck G, Mallek R, Gebauer A, Tscholakoff D. Duplex ultrasound and color coded Doppler ultrasound of visceral blood vessels in abdominal diseases. Wien Klin Wochenschr 1992; 104: 227-33.

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Figure 1. Ultrasonography of the portal vein in healthy patient. Real time and pulsed Doppler technique. Blood flow velocity is 0.20 m/s. GVS, graphic velocity spectrum. PV, portal vein segnment. SL, scanning line, with Doppler window, DW.
 

Figure 2. Ultrasonography of the portal vein in patient with portal hypertension. Pulsed and color Doppler tchnique. Blood flow velocity is 0.07 m/s. PV, portal vein which is gray colored because of BW fotography. SL, scanning line, whith Doppler window, DW.
 

Figure 3. Ultrasonography of the splenic vein in patient with portal hypertension. Pulsed and color Doppler tchnique. Blood flow velocity is 0.10 m/s. SV, splenic vein dark grey colored because of BW photography. GVS, graphic velocity spectrum. SL, scanning line with Doppler window, DW.

 

 

 

 

Table 1. Portal and splenic vein blood velocity in patients with portal hypertension

 

variable

statistic parameter

X

SD

V%

Max

Min

R

Portal vein blood velocity (cm/s)

17,66

1,65

9,33

23,00

15,00

8,00

Splenic vein blood velocity (cm/s)

17,26

1,90

11,00

23,00

15,00

8,00

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2. Portal and splenic vein blood velocity in healthy examinees

 

variable

statistic parameter

X

SD

V%

Max

Min

R

Portal vein blood velocity (cm/s)

9,38

1,42

15,08

13,00

6,00

7,00

Splenic vein blood velocity (cm/s)

10,17

1,28

12,57

12,00

7,00

5,00

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3. The significance of the differences in the arithmetic mean of the blood flow velocity with patients and control group

 

variable

sample of patients

control group sample

t - test

X

SD

X

SD

t

significance

Portal vein velocity (cm/s)

9,38

1,42

17,66

1,65

-28,95

t>t 0,001

Splenic vein velocity (cm/s)

10,17

1,28

17,26

1,90

-23,28

t> 0,001

 

 

 

 

 

 

 

 

 

 

 

 

1