Portal hypertension

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Portal hypertension
Classification and external resources
Gray591.png
The portal vein and its tributaries.
ICD-10 K76.6
ICD-9 572.3
DiseasesDB 10388
eMedicine radio/570 med/1889
MeSH D006975

In medicine, portal hypertension is hypertension (high blood pressure) in the portal vein system, which is composed of the portal vein, and its branches and tributaries.

Portal hypertension is defined as elevation of hepatic venous pressure gradient to >5mmHg. Generally, in clinical practice the pressure is not measured directly until the decision to place a transjugular intrahepatic portosystemic shunt (TIPS) has already been made. As part of that procedure, a hepatic vein wedge pressure is measured with the assumption of no pressure drop across the liver yielding portal vein pressure.

Causes

Causes can be divided into prehepatic, intrahepatic, and posthepatic.

Signs and symptoms

Consequences of portal hypertension are caused by blood being forced down alternate channels by the increased resistance to flow through the systemic venous system rather than the portal system. They include:

Diagnostics

HVPG (hepatic venous pressure gradient) measurement has been accepted as the gold standard for assessing the severity of portal hypertension,3 and replaced the old one - contrast angiography.4 Portal hypertension is defined as HVPG greater than or equal to 5mm Hg.5

Treatment

Portosystemic Shunts

These can be categorized by several different concepts: selective vs non-selective, mesocaval vs portocaval, and the specific arrangement of vessels, e.g. end-to-side or side-to-side. Selective shunts select non-intestinal flow to be shunted to the systemic venous drainage while leaving the intestinal venous drainage to continue pass through the liver. The most well known of this type is the splenorenal, or Warren, shunt. This connects the splenic vein to the left renal vein thus reducing portal system pressure while minimizing any encephalopathy. In an H-shunt, which could be mesocaval (from the superior mesenteric vein to the inferior vena cava) or could be, unlikely, portocaval (from the portal vein to the inferior vena cava) a graft, either synthetic or the preferred vein harvested from somewhere else on the patient's body, is connected between the superior mesenteric vein and the inferior vena cava. The size of this shunt will determine how selective it is.

It should be noted that with the advent of TIPS, these are very rarely performed anymore. TIPS has the advantage of being much easier to perform and it doesn't disrupt any of the liver's vascular, which will be needed for a given patient's hoped for liver transplant. In general non-selective shunts are emergent surgeries that are done as quickly as possible to minimize intraoperative blood loss. On the contrary a splenorenal shunt would be an elective procedure due to its great technical demands. Further, contributing to their rare use today is the fact that few, if any, current general surgery residents are trained in how to carry out these surgeries.

Prophylaxis of variceal bleeding

Both pharmacological (non-specific ß-blockers like Propranolol and isosorbide mononitrate) and endoscopic (banding ligation) treatment have similar results. TIPS (transjugular intrahepatic portosystemic shunting) is superior to either of them at reducing rate of rebleeding. Disadvantages of TIPS include high cost and increased risk of hepatic encephalopathy, and it does not improve the mortality rate.

Management of active variceal bleeding

After resuscitation, which may require blood transfusion, the management of active variceal bleeding includes administering vasoactive drugs (somatostatin, octreotide or terlipressin), endoscopic banding ligation, balloon tamponade and TIPS(Transjugular intrahepatic portocaval shunt)

Management of ascites

This should be gradual to avoid sudden changes in systemic volume status which can precipitate hepatic encephalopathy, renal failure and death. The management includes salt restriction, diuretics (spironolactone), paracentesis, transjugular intrahepatic portosystemic shunt (TIPS) and peritoneovenous shunt.

Control of hepatic encephalopathy

A standard treatment plan may involve lactulose, bowel enemas, and use of oral antibiotics such as neomycin, metronidazole, vancomycin, and the quinolones. Previously, restriction of dietary protein was recommended but this is now refuted by a clinical trial which showed no benefit.6 Instead, the maintenance of adequate nutrition is now advocated.7

References

  1. ^ Perkins, [edited by] Vinay Kumar, Abul K. Abbas, Jon C. Aster ; artist, James A. Robbins basic pathology (9th ed. ed.). Philadelphia, PA: Elsevier/Saunders. p. 608. ISBN 978-1-4377-1781-5. 
  2. ^ "Portal Hypertension". Retrieved 2007-12-07. 
  3. ^ Damping Index of Doppler Hepatic Vein Waveform - Portal Hypertension: Discussion, http://www.medscape.com/viewarticle/564073_4
  4. ^ Appleton & Lange's review for the ultrasonography examination, By Carol Krebs, Charles S. Odwin, Arthur C. Fleischer, page 309
  5. ^ http://www.drfalkpharma.de/fileadmin/media/praesentationen/fs163/S4_P2.pdf
  6. ^ Córdoba, J.; López-Hellín, J.; Planas, M.; Sabín, P.; Sanpedro, F.; Castro, F.; Esteban, R.; Guardia, J. (2004). "Normal protein diet for episodic hepatic encephalopathy: Results of a randomized study". Journal of Hepatology 41 (1): 38–43. doi:10.1016/j.jhep.2004.03.023. PMID 15246205.  
  7. ^ http://www.patient.co.uk/doctor/Hepatic-Encephalopathy.htm

External links