Nur Amalina Aminuddin082012100067

Portal Hypertension

AnatomyPhysiologyPathology

Types of circulation

Systemic Aka greater circulation.RV LVProvide blood circulation

to organs Pulmonary

Aka lesser circulationLVRVOxygenation of blood

Portal

Portal circulation part of systemic circulation passes through two sets of capillaries before draining into a

systemic vein.

Portal vein Vein draining the first capillary network

Efferent arteryArtery draining the first capillary network

Examples:Arterial portal system

Hepatic portal circulation Hypothalamo hypophyseal portal circulation

Venous portal system Renal portal circulation

Hepatic Portal

Circulation

Drains the deoxygenated blood from lower esophagus upper anal canal, pancreas, spleen, gall bladder

Carries nutrient rich blood from intestines to liver Importance:

First bypass effectCertain drugs become inactive after being metabolised by liver,

hence route other than oral should be giveneg. Nitroglycerin, midazolam

Activation of prodrug Requires metabolism by liver to activateEg.Dextometrophan, fospropanol

Drainage of portal circulationInferior mesentric v splenic vSplenic v +superior mesentric v portal veinDirect into portal vein

Left and right gastric vPosterior superior pancreatoduodenal v

Portal vein banches into left and right portal vein cystic v drains directly into right portal vein

Passed throught liver sinusoids into hepatic vein inferior vena cava

Portocaval anastomosis

Anastomosis between hepatic portal circulation and systemic circulation

Become dilated as reversal of flow occur in portal hypertension

Region Portal circulation Systemic circulation

Esophageal Esophageal branch of left gastric vein

Esophageal branches of Azygos vein

Rectal Superior rectal veinMiddle rectal veins and inferior rectal veins

Paraumbilical Paraumbilical veins Superficial epigastric vein

Retroperitoneal

Splenic veinRenal vein, suprarenal vein, paravertebral vein, and gonadal vein

Right colic vein, middle colic vein, left colic vein

Retroperitoneal veins of Retzius

Intrahepatic

Perihepatic veins of Sappey

Superior epigastric vein

Left branch of portal vein Inferior vena cava

Table egion Name of clinical condition Portal circulation Systemic

circulation

Esophageal Esophageal varices

Esophageal branch of left gastric vein

Esophageal branches of Azygos vein

Rectal Rectal Varices Superior rectal vein

Middle rectal veins and inferior rectal veinsParaumbilical Caput medusae Paraumbilical vein

sSuperficial epigastric vein

Retroperitoneal

Splenorenal Shunt[2] Splenic vein

Renal vein, suprarenal vein, paravertebral vein, and gonadal vein

(no clinical name)[3]

Right colic vein, middle colic vein, left colic vein

Retroperitoneal veins of Retzius

Intrahepatic

Hepatic pseudolesions[4]

Perihepatic veins of Sappey

Superior epigastric vein

Patent ductus venosus

Left branch of portal vein Inferior vena cava

High Blood Flow ¼ Cardiac ¼ Cardiac

OutputOutput1.5 L/min1.5 L/min

Hepatic Hepatic ArteryArtery

1/3 Flow1/3 Flow2/3 Oxy2/3 Oxy

Portal VeinPortal Vein2/3 Flow2/3 Flow1/3 Oxy1/3 Oxy

Low Pressure Gradient

Very Low Resistance

Portal hypertension Elevation of the

hepatic venous pressure gradient to >5 mmHg

PathophysiologyIncreased resistance P= F X RContraction of smooth muscle cells Scarring of parenchymaDecreased NO production

Increased portal blood flow from hyperdynamic circulation

Caused by arterial vasodilation mediated by NO

Lead to increased efflux of blood to portal system

HEPATIC ARTERY BUFFER RESPONSE

P= F X R

Portosystemic ShuntRise in portal

pressure

Reversal of flow

Dilated collateral vessel

Causes Classification Causes Prehepatic •Portal vein thrombosis

•Splenic vein thrombosis •Massive splenomegaly

Hepatic •Cirrhosis •Alcoholic hepatitis•Venoocclusive disorder•Congenital hepatic fibrosis

Posthepatic •Budd Chiari syndrome •Inferior vena caval webs•Congestive cardiac failure

Reference Robbins and Cottran’s Pathological Basis of

Disease, 8th edition,2010Guyton and Hall’s Textbook of Medical Physiology,

12th edition, 2011Harrison’s Principle of Internal Medicine, 19th

edition, volume 2 , 2015.https://www.ncbi.nlm.nih.gov/books/NBK53067/

hepatic Physiology and Pathophysiology https://www.ncbi.nlm.nih.gov/pmc/articles/

PMC3012579/Regulation of hepatic blood flow,2010