Here, we present a protocol for measurement of hepatic venous pressure gradient (HVPG),the gold standard to diagnose clinically significant portal hypertension. Moreover, we describe how to perform a transjugular liver biopsy within the same session.
Diagnosing portal hypertension in patients with advanced chronic liver disease has important prognostic implications. Assessing the severity and treatment response allows for individualized treatment approaches in these patients. Measurement of the hepatic venous pressure gradient, or HVPG, is the gold standard for diagnosing of portal hypertension in patients with advanced chronic liver disease.
The prognostic value of HVPG and the clinical benefits of a decrease in HVPG have been established over a broad spectrum of etiologies of advanced chronic liver disease and also disease severity. HVPG measurement provides important insights into the complex interplay between portal hypertension and the related pathophysiological mechanisms that drive the development of clinical events in cirrhosis. Before placement, flush the balloon catheter with contrast medium and inflate and deflate the balloon several times with the catheter tips submerged in saline to check the integrity of the instrument.
No air bubbles should occur. Moisten the outside of the balloon catheter with additional sterile saline solution before inserting the catheter into the vascular access sheath. Advance the catheter under fluoroscopic guidance into the inferior cava vein, or IVC, using slight rotations to align the tip of the catheter toward the back of the patient to advance from the right atrium to the IVC.
To advance the catheter from the IVC into the hepatic vein, repeatedly moved the tip of the balloon catheter to the right toward the suspected area of the junction of the hepatic veins and the IVC to obtain access to the hepatic veins. Advance the catheter to a stable position that allows repeat measurement of the free hepatic venous pressure at a two to four centimeter distance from the opening of the junction into the IVC with sufficient space for the inflated balloon. Confirming its efficient wedge position of the balloon catheter in the hepatic vein is critical for obtaining reliable readings.
This is confirmed by dye injection and the fluoroscopy. To check the adequacy of the vein occlusion, inflate the balloon with about two milliliters of air and about five milliliters of contrast dye until the hepatic vein distal to the inflated balloon can be visualized. Observe the stasis of the contrast medium and exclude any wash out due to insufficient occlusion of the venous lumen by the balloon or the presence of shunts.
Then deflate the balloon and flush the lumen of the catheter with saline. To assess the hepatic venous pressure gradient, use an infusion line to connect to the vascular lumen of the balloon catheter to the pressure transducer and begin recording the free hepatic venous pressure with the tip of the balloon two to four centimeters from the opening of the hepatic vein to the IVC. The wave form of the curve of the free hepatic venous pressure gradient might show slight oscillations related to the heartbeat.
Inflate the balloon and continue recording the wedge hepatic venous pressure until the measurement becomes a stable horizontal line with no variations over time. After repeating the free and wedge hepatic venous pressures at least three times record pressure in the IVC at the level of the ostium of the hepatic vein as well as the right atrial pressure. Before beginning the biopsy procedure, flush the biopsy needle introducer sheath with sterile saline.
Check the system for smooth access and advance the biopsy needle introducer sheath into a hepatic vein as demonstrated for the balloon catheter. Gently advance the 16 gauge needle through the biopsy needle introducer sheath into the hepatic vein. To load the transjugular core liver biopsy needle, pull the grip until the shooting mechanism is loaded.
Advance the core biopsy set through the biopsy needle until the tip of the core biopsy set approaches the end of the biopsy needle in the hepatic vein. Instruct the patient to hold their breath and advance the core biopsy set into the liver parenchyma. Pull the trigger of the shooting mechanism to perform the core biopsy and advise the patient to breathe normally.
Remove the needle without removing the needle introducer sheath and harvest the liver sample. When all of the biopsies have been obtained inject five to 10 milliliters of contrast medium over the catheter introducer sheath to rule out perforation of the liver capsule and remove the biopsy needle introducer sheath. In a cirrhotic patient with varices or with portal hypertensive ascites, the HPVG values are expected to be at least greater to or equal to 10 millimeters of mercury.
In this example, the continuous green line indicates the recorded free hepatic venous pressure of five millimeters of mercury and discontinuous red line indicates the recorded wedged hepatic venous pressure of 26 millimeters of mercury. Thus, the calculated hepatic venous pressure gradient in this patient is 21 millimeters of mercury which indicates clinically significant portal hypertension Major complications of HVPG measurement and transjugular liver biopsy are rare and mainly related to the central venous access. Here, the use of ultrasound guided central venous access will largely reduce the risk of these complications.
Adequate training of central venous access development is critical to reduce the risk of major complications of HPVG measurement. Non-invasive tests are not sufficiently accurate for assessing the severity of portal hypertension in patients with CSPH and have limited accuracy for monitoring the evolution of portal hypertension after etiologically and medical therapies.
