Portal Hypertension Flashcards
Two general concepts that result in an increase in portal hypertension (PH).
- Increase in venous resistance
- Increase in portal venous flow
(pressure = resistance x flow)
Most common cause of portal hypertension.
Cirrhosis - intrahepatic PH
leading cause of increased resistance in hepatic vasculature
Most common cause of pre-sinusoidal PH.
Schistosomiasis (S. mansoni)
How does cirrhosis lead to intrahepatic PH?
- Structural: fibrosis of the sinusoids causes blood to back up in the liver.
- Functional: active vasoconstriction due to release of mediators from the liver and decrease in Nitric Oxide release.
How does cirrhosis also lead to an increase in NO which actually causes worse PH?
Cirrhosis causes a drop in NO release inside the liver vasculature. But this triggers an upstream release of NO in the extra-hepatic portal vessels increasing blood flow into the “plugged up” liver. One of the component of the PH equation is “flow” and this increases flow into the liver.
Describe the effect of Hyperdynamic Circulation caused by cirrhosis.
- Cirrhosis leads to PH
- Portal venous dilation occurs due to increased NO release
- Increased portal blood volume leads to decreased arterial blood volume
- Decreased arterial blood volume is sensed by arterial baroceptors and the macula densa in the kidneys
5 Renin-Ag-Aldosterone system is activated to increase sodium and chloride and water absorption - Leads to overall increased body fluid volume which increases flow in the portal system.
Hepatic Venous Pressure Gradient (HVPG) required for varices to form.
> 12 mmHg
How is HVPG calculated?
HVPG = WHVP - FHVP
WHVP: wedged hepatic venous pressure, measureed by “wedging” a balloon catheter into the hepatic sinusoids and inflating to record pressure.
FHVP: free hepatic venous pressure, measured by deflating the balloon and recording the pressure in the sinusoid.
What HVPG would be expected in Pre-sinusoidal PH?
Normal (3-5mmHg)
-blockage or congestion occurs proximal to the site of measurement (sinusoids)
What HVPG would be expected in sinusoidal PH?
Elevated
-disease occurs within the site of measurement (sinusoids)
What HVPG would be expected in Post-sinusoidal PH?
Elevated
-similar to sinusoidal PH
What HVPG would be expected in Post-Hepatic PH?
May appear normal
-both WHVP and FHVP may be elevated and yield a 3-5mmHg difference
What are 3 predictors of variceal hemorrhage?
- Varix size (larger is worse)
- Red Signs (a red wale sign is a red streak along a varix seen on endoscopy)
- Child-Pugh Class B or C (used to assess prognosis of chronic liver disease)
Higher tension on a varix will increase its chance to rupture. What factors account for the tension?
T = tp x r/w
tp - transmural pressure: produced from within the varix and from the esophagus.
r - radius of varix: larger varix is more likely to rupture
w - width of varix wall: thicker wall is stronger and decreases chance of rupture
Which factor that contributes to tension is targeted by physicians to decrease likelihood of rupture?
Transmural pressure:
Portal venous pressure can be influenced by medication and a decrease in portal pressure will decrease tp.
How do vasoconstrictors and TIPS reduce chances of esophageal varix rupture?
Vasoconstrictor: increases resistance in the splanchnic arteries which decreases portal blood flow
TIPS: creates a shunt that decreases resistance to flow in the portal system
In treatment of varices or variceal hemorrhage, what is management to prevent varices in patients that have cirrhosis but have not yet developed varices?
No specific treatment has worked. Endoscopic monitoring every 2-3 years is recommended.
In treatment of varices or variceal hemorrhage, what is the best medication to provide patients with medium or large varices to prevent rupture?
Non-selective Beta Blockers
-propranolol, nadolol
(NOT metoprolol)
Medications are best to prevent medium or large variceal rupture. Name one contraindication where beta blockers cannot be used and the alternative treatment.
Lung pathology (Asthma, COPD): non-selectives will prevent bronchiole dilation because Beta-2 receptors are blocked and aggravate the asthma.
VBL: variceal band ligation is alternative - involves putting a rubber band on the origin of the varix to prevent any more blood from flowing into the varix.
In treatment of varices or variceal hemorrhage, what is the best treatment in patients with small varices?
Screening endoscopy every 1-2 yrs.
In treatment of varices or variceal hemorrhage, what are the 3 steps in general management once a varix has ruptured?
- Fluid Resuscitation
- Do not overtransfuse (can lead to more bleeding due to increased portal flow)
- Antibiotic Prophylaxis
In treatment of varices or variceal hemorrhage, what are 3 specific strategies for treating a patient with a ruptures varix?
- Vasoconstrictors: terlipressin, nitroglycerin
- Endoscopic therapy: ligation, sclerotherapy
- Shunts: TIPS, surgical shunt
What is the mechanism of Endoscopic Variceal Band Ligation (VBL)?
Placement of rubber rings on variceal columns with the objective of interrupting blood flow and developing necrosis of mucosa and submucosa and replacement of varices by scar tissue.
What is the main drug used with VBL?
Octreotide: somatostatin analog
What is TIPS and how does it work?
Transjugular Intrahepatic Portosystemic Shunt:
A catheter is surgically placed in the liver basically connecting a main branch from the portal vein to one of the hepatic veins to exponentially decrease resistance in the portal blood flow. Diverts blood from varices in the esophagus to treat a rupture.
Two major complications of TIPS.
Liver Failure: due to shunted blood flow depriving hepatocytes of nutrients. The hepatocytes would have to rely on the hepatic artery for blood supply which normally only accounts for about 30% of flow.
Hepatic Encephalopathy: shunting blood away from hepatocytes decreases the metabolism and detoxification of blood. Mainly a rise in ammonia levels (no urea cycle) in the blood is indicated in causing the CNS symptoms.
What are the treatment regimens in patients with a first esophageal bleed?
- Safe Vasoconstrictive Drug + endoscopic therapy (VBL) + Prophylaxis antibiotics
If 1 fails:
2. TIPS or another type of shunt
What is the most effective treatment to prevent re-bleed of esophageal varices?
VBL + non-selective beta blockers
What is the best treatment for recurrent bleeding esophageal varices in patients that fail with VBL + beta blockers?
TIPS
Where can you look to for concise guidelines for treating various stages of esophageal varices.
Slide 99 on PH lecture
Where are GOV1 and GOV2 gastric varices located and how are they treated?
Near the gastroesophageal junction. Treated the same as esophageal varices.
What is treatment for IGV1 varices?
IGV1 (isolated gastric varices near fundus):
- Should check for splenic vein thrombosis and possible splenectomy.
- If bleeding, VBL + beta blockers + antibiotics
- If 2 fails, TIPS
What are the endoscopic features and treatments for mild and severe Portal Hypertensive Gastropathy?
Mild:
Endo - mosaic, cobblestone appearance
Tx - none
Severe:
Endo - mosaic patten, red signs
Tx - Beta blockers and/or TIPS
