Portal vein

Source: Wikipedia, the free encyclopedia.
(Redirected from
Hepatic portal vein
)
This article is about the vein connected to the liver. For veins connecting two systems of capillary beds, see portal venous system.
Portal vein
pancreatic vein
Drains toliver sinusoid
Identifiers
Latinvena portae hepatis
MeSHD011169
TA98A12.3.12.001
TA25092
FMA50735
Anatomical terminology]

The portal vein or hepatic portal vein (HPV) is a

toxins extracted from digested contents. Approximately 75% of total liver blood flow is through the portal vein, with the remainder coming from the hepatic artery proper. The blood leaves the liver to the heart in the hepatic veins
.

The portal vein is not a true vein, because it conducts blood to capillary beds in the liver and not directly to the heart. It is a major component of the hepatic portal system, one of three portal venous systems in the human body; the others being the hypophyseal and renal portal systems.

The portal vein is usually formed by the confluence of the

pancreatic vein
.

Conditions involving the portal vein cause considerable illness and death. An important example of such a condition is elevated

non-alcoholic fatty liver disease.[1][2]

Structure

Measuring approximately 8 cm (3 inches) long in adults,

right upper quadrant of the abdomen, originating behind the neck of the pancreas.[4]

In most individuals, the portal vein is formed by the union of the superior mesenteric vein and the splenic vein.[5] For this reason, the portal vein is occasionally called the splenic-mesenteric confluence.[4] Occasionally, the portal vein also directly communicates with the inferior mesenteric vein, although this is highly variable. Other tributaries of the portal vein include the cystic and the left and right gastric veins.[6] and also pararumbilical vein and prepyloric vein.

Tributaries of the hepatic portal vein[6]

Immediately before reaching the liver, the portal vein divides into right and left. It ramifies further, forming smaller venous branches and ultimately portal venules. Each portal venule courses alongside a hepatic arteriole and the two vessels form the vascular components of the

hepatic sinusoids to supply blood to the liver.[6]

Portacaval anastomoses

The

systemic venous system. In cases of portal hypertension
these anastomoses may become engorged, dilated, or varicosed and subsequently rupture.

Accessory hepatic portal veins

Accessory hepatic portal veins are those veins that drain directly into the liver without joining the hepatic portal vein. These include the

paraumbilical veins as well as veins of the lesser omentum, falciform ligament, and those draining the gallbladder wall.[4]

Function

The portal vein and

hepatic arteries form the liver's dual blood supply. Approximately 75% of hepatic blood flow is derived from the portal vein, while the remainder is from the hepatic arteries.[4]

Unlike most veins, the portal vein does not drain into the

hepatic vein
.

Clinical significance

Portal hypertension

Main article: Portal hypertension

Increased blood pressure in the portal vein, called portal hypertension, is a major complication of liver disease, most commonly cirrhosis.[7] A dilated portal vein (diameter of greater than 13 or 15 mm) is a sign of portal hypertension, with a sensitivity estimated at 12.5% or 40%.[8] On Doppler ultrasonography, the main portal vein (MPV) peak systolic velocity normally ranges between 20 cm/s and 40 cm/s.[9] A slow velocity of <16 cm/s in addition to dilatation in the MPV are diagnostic of portal hypertension.[9]

Clinical

spider nevi, caput medusae, and palmar erythema.[10]

Pulsatility

Doppler ultrasonography of the portal vein over 5 seconds, showing peaks of maximal velocity, as well as points of minimal velocity.

Portal vein pulsatility can be measured by Doppler ultrasonography. An increased pulsatility may be caused by cirrhosis, as well as increased right atrial pressure (which in turn may be caused by right heart failure or tricuspid regurgitation).[9] Portal vein pulsatility can be quantified by pulsatility indices (PI), where an index above a certain cutoff indicates pathology:

Pulsatility indices (PI)
Index Calculation Cutoff
Average-based (Max - Min) / Average[9] 0.5[9]
Max-based (Max - Min) / Max[11] 0.5[11][12] - 0.54[12]

Infection

Main article: Pylephlebitis

Pylephlebitis is infection of the portal vein, usually arising from an infectious intra-abdominal process such as diverticulitis.[13][14]

Portal venous gas

Hepatic portal venous gas is a rare finding on radiological exams. Gas is shown to enter the portal venous system. It is most commonly caused by intestinal ischemia but has also been associated with colon cancer.[15]

Additional images

  • Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries
    Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries
  • Section across the portal triad of the pig
    Section across the
    portal triad
    of the pig
  • Longitudinal section of a small portal vein and canal
    Longitudinal section of a small portal vein and canal
  • Hepatic portal vein. Plastination technique.
    Hepatic portal vein. Plastination technique.
  • Hepatic portal vein. Abdominal cavity. Deep dissection.
    Hepatic portal vein. Abdominal cavity. Deep dissection.
  • Hepatic portal vein. Visceral surface of liver.
    Hepatic portal vein. Visceral surface of liver.

References

  1. S2CID 25169877
    .
  2. PMID 32818561
    .
  3. ISBN 978-0-7817-7174-0
    .
  4. ^
    ISBN 978-3-540-65797-2
    .
  5. ISBN 978-1-55009-364-3
    .
  6. ^ a b c Henry Gray (1901). Anatomy, Descriptive and Surgical (16 ed.). Philadelphia: Lea Brothers. p. 619.
  7. ISBN 978-0-632-05582-1
    .
  8. PMID 19858596
    .
  9. ^
    PMID 26169079
    .
  10. ISBN 978-1-85996-164-3
    .
  11. ^
    ISSN 0195-668X
    .
  12. ^
    ISBN 9783540938422
    .
  13. PMID 8589130
    .
  14. PMID 8488411
    .
  15. PMID 29390409
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Portal_vein&oldid=1209799302"