Chapter 5: Hemodynamic Evaluation of the Liver and Transjugular Liver Biopsy Because portal hypertension (PHT) is the earliest and most important consequence of cirrhosis and underlies most of the clinical complications of the disease, hemodynamic evaluation of the liver carries the most useful and critical information to diagnose, stratify their risks, and monitor of the efficacy of medical treatment of these patients.1 Recent studies have shown that measurement of hepatic venous pressure gradient (HVPG) has a greater diagnostic accuracy than liver biopsy in the diagnosis of cirrhosis even though liver biopsy remains the “gold standard” in the diagnosis of cirrhosis.2 Transjugular catheterization of a hepatic vein with measurement of the HVPG is considered the gold standard method to determine the portal pressure in clinical practice.3,4 It is calculated as the difference between the wedged hepatic venous pressure (WHVP) optimally obtained by an inflated catheter balloon in the mid or distal hepatic vein and the free hepatic venous pressure (FHVP) with the balloon deflated.1–3 This method, in the absence of presinusoidal obstruction, indirectly reflects the portal pressure. Several longitudinal studies have shown that WHVP provides an accurate estimation of the portal pressure in alcoholic and viral related cirrhosis.1,5,7,13 Thus, the HVPG has a greater diagnostic accuracy than liver biopsy in the diagnosis of cirrhosis. In addition to the degree of PHT, the HVPG provides an excellent tool to evaluate response to the pharmacologic and nonpharmacologic interventions as well to reliably predict the outcomes in patients with cirrhosis-related PHT.10–12 In addition to the hemodynamic pressure measurements, other procedures can be performed during hepatic vein catheterization. These procedures include transjugular liver biopsy (which is discussed at the end of this chapter), CO2 portography, and right heart catheterization in suspected congestive hepatopathy or investigation of cardiopulmonary complications caused by cirrhosis. The most frequent procedure performed in conjunction with pressure measurement is transjugular liver biopsy (TJLB).14,15 In the past, aspiration specimens obtained by a transjugular approach were considered to be inferior or less satisfactory compared with the percutaneous approach because they were smaller and more fragmented.16 However, with the improvement and widespread use of new Tru-Cut type needles and technique improvement, the samples are now considered equal for the diagnosis and almost comparable for staging and grading chronic liver disease.14,17 • Ultrasound machine with linear array probe • State-of-the-art angiography suite • Micropuncture set (Cook Medical, Bloomington, IN) or 18-gauge access needle • 9-French × 35-cm bright tip or 10-Fr × 45-cm flexor vascular sheath • 180-cm × 135-cm Bentson guidewire (Cook Medical) • 6.5-Fr flow-directed balloon catheter made by Cook Medical • 8.5- to 11.5-mm, 6-Fr Berenstein occlusion balloon catheter (Boston Scientific, Natick, MA) • Pressure transducer system • Obtain informed consent. • Ensure no contrast allergy; otherwise, CO2 can be used as contrast media; ensure a platelet count greater than 50,000/μL. • The patient should have nothing by mouth for 4 to 6 hours before the procedure. • Coagulation profile: platelets: should be greater than 5000 to 10,000; international normalized ratio should be less than 3.0 to 3.5. 1. Sedation: Almost all cases can be done with conscious sedation, providing comfort during the procedure. General anesthesia could be used in claustrophobic or pediatric patients. Conscious sedation is obtained with midazolam, up to 0.02 mg/kg at 0.5- to 1-mg increments, and fentanyl, 0.05 to 2 g/kg at 25 to 50 mcg per increment, and is generally well tolerated. Higher doses of midazolam or deep sedation significantly alter pressure measurements. 2. Monitoring: As recommended by the American Society of Anesthesia, all patients should be monitored for blood pressure, heart rate, oxygen saturation, end-tidal CO2, and electrocardiography. Cardiac ectopies and arrhythmias have been reported during catheterization of the hepatic veins, particularly in patients with electrolyte abnormalities. 3. Venous access: Venous access is obtained under real-time ultrasound guidance using a micropuncture access needle set (Cook Medical) or an 18-gauge needle. At our institution, all access is obtained using a micropuncture access set. The right jugular vein (RJV) has been the main vessel access. The theory behind supported by straighter anatomy for the access of the hepatic veins in comparison with the left IJ. However, our unpublished experience shows no significant difference. Right internal jugular vein obstruction may become a problem in patients with end-stage renal disease or previous history of RJV catheterization; in these cases, alternative access such as the external jugular, left internal jugular, or subclavian approach should be used. In these circumstances, the patients usually just are slightly more uncomfortable requiring more sedation. After venous access is obtained, a 9-Fr, 45-cm bright tip or 10-Fr flexor vascular sheath (Cook Medical) is advanced over a 0.035-inch guidewire into the inferior vena cava (IVC). It is always recommended to exclude the presence of an IVC filter before advancing the guidewire. There are some reports in the literature of IVC filter migration and guidewire entrapment within a filter. 4. Hepatic vein catheterization: A 5-Fr multipurpose catheter is then used to perform selective catheterization of the right or middle hepatic vein. When the access into the hepatic veins is difficult given the patient anatomy or in overweight or transplanted patients, reverse-curve catheters such as AL-1.5 6-Fr Guiding Launcher, 5-Fr Simmons-1 Cobra, or even, a Shetty catheter is recommended. Our personal experience shows that the 6-Fr Launcher catheter is the best catheter to obtain access into the hepatic vein after failure of a multipurpose catheter ( 5. Hepatic venogram: A hepatic venogram is suggested to confirm the position and the patency of the selected hepatic vein ( 6. Transducer calibration: Most transducers come precalibrated. The transducer is placed at the level of the heart, preferably at an approximate level of the mid right atrium. With transducer open to air (zero pressure), adjust the transducer to read zero. 7. Pressure tracings and scale: Permanent records should be captured either on paper or electronically. Use an appropriate scale for venous pressure measurements (full range up to 50 mm Hg) with appropriate visualization of the baseline because the normal right atrial pressure could be from −5 mm Hg. 8. FHVP: The FHVP is measured by maintaining the tip of the catheter “free” in the mid hepatic vein. The FHVP should be close to IVC pressure; if the difference between these pressure values is more than 2 mm Hg, it is likely that the catheter is inadequately placed. In these cases, IVC pressure should be used for calculating HVPG. 9. WHVP: The WHVP is measured by occluding the hepatic vein, either by “wedging” the catheter into a small branch of a hepatic vein or by inflating a balloon-catheter. Occlusion of the hepatic vein by inflating a balloon is preferred because the volume of the liver circulation transmitting portal pressure is much larger than that attained by wedging the catheter. This reduces the variability of the measurements. Adequate occlusion of the hepatic vein is confirmed by slowly injecting 5 mL of contrast into the vein with the balloon inflated. No reflux of the contrast or washout through communications with other hepatic veins should be observed. Otherwise, WHVP might underestimate portal pressure. Fig. 5.2 Wedge position on a balloon catheter. Posterior-anterior projection (PA) spot film demonstrates the occlusion-balloon catheter inflated with air. The catheter is positioned in a central location within the right hepatic vein. Overall, the hemodynamic evaluation of the liver is a really safe procedure with almost no major complications.15 Minor complications reported are infrequent and include bleeding and/or hematoma at the puncture site. Most reported major complications are caused by the transjugular liver biopsy part rather than hemodynamic evaluation.17 Hepatic venous pressure gradient measurement has evolved from diagnostic purposes to be considered the most reliable tool to assess the severity, prognosis, and response to treatment of chronic liver disease and liver cirrhosis, including the risk of the complications such as ascites, variceal bleeding, encephalopathy, and hepatorenal syndrome.9 Because the HVPG is a strong and independent predictor of outcomes in both compensated and decompensated cirrhosis, a new clinical classification system of cirrhosis that incorporates histologic, clinical, hemodynamic, and biologic features has been developed ( Multiple studies have been shown that an HVPG greater than 10 mm Hg correlates with the presence of gastroesophageal varices.1,2,4 Ripoll et al found that HVPG of 10 mm Hg or greater predicts the likelihood of developing hepatic decompensation in 40% at 4 years and development of hepatocellular carcinoma (HCC).18,19 For this reason, the term “clinically significant PHT” has been recognized when the HVPG is greater than 10 mm Hg. Patients with compensated cirrhosis gain 10% risk of decompensation at 5 years for each 1-mm Hg increase of the HVPG.18,20 The HVPG is also important in patients with decompensated cirrhosis, providing the mortality risk during the following years. In the patient with an acute variceal hemorrhage, a gradient of more than 20 mm Hg is an independent predictor of rebleeding and death.12,21 For this reason, 16 mm Hg is considered the optimum cutoff value in decompensated cirrhosis.6,22 In patients with compensated cirrhosis, a gradient of 10 mm Hg or more is an independent predictor for developing HCC with a sixfold increased risk compared with patients with a gradient less than 10 mm Hg.19 The gradient also has an important role in the treatment of HCC. In patients with compensated cirrhosis with a resectable HCC, the presence of a gradient greater than 10 mm Hg markedly increases the risk of hepatic decompensation 3 months after surgery. For this reason, surgical resection for HCC is reserved only in patients without clinically significant PHT (HVPG <10 mm Hg).23 Variceal bleeding occurs when HVPG is greater than 12 mm Hg. Longitudinal studies have demonstrated that if the gradient decreases to less than 12 mm Hg or at least 20% from the baseline by medical treatment (drug therapy), spontaneously, or by a transjugular intrahepatic portosystemic shunt (TIPS) procedure, the variceal bleeding is prevented, and varices decrease in size.24,25 In patients who survive a variceal bleeding episode, the reduction of the gradient less than 12 mm Hg or more than 20% from the baseline is the strongest independent predictor of protection from subsequent bleeding episode, as well as other PHT-related complications such as ascites, spontaneous bacterial peritonitis, or hepatorenal syndrome. Two studies have shown that evaluation of the acute HVPG response to intravenous administration of propranolol is a practical tool in predicting the efficacy of nonselective beta-blockers in preventing variceal bleeding.26,27 The acute HVPG response to propranolol was independently associated with survival in these patients. Despite rapidly improving serologic, biomolecular testing, and noninvasive methods to assess the degree of cirrhosis, liver biopsy still considered the “gold standard” for the evaluation of acute and chronic liver diseases. Histologic assessment provides critical prognostic information and is frequently pivotal in therapeutic decisions not only for diagnosis but also to assess progression and response to therapy of chronic liver diseases.
Introduction
Hemodynamic Evaluation of the Liver
Material Required for the Procedure
Preprocedure Preparation
Technique
Fig. 5.1A).
Fig. 5.1B). The multipurpose catheter is then exchanged for an occlusion balloon catheter, and wedge hepatic and free hepatic venous pressures are then obtained. The balloon catheter is positioned at the mid hepatic vein level, estimated by the hepatic vein venogram (
Fig. 5.2). If the hepatic vein is extremely large in diameter, then the catheter is positioned more distally.
Complications
Interpretation of the Hepatic Venous Pressure Gradient
Table 5.1). This new classification is necessary for overcoming the limitation of prematurely concluding cirrhosis as an end stage of chronic liver disease. This system classified the distinction of compensation and decompensation, which is mainly defined by clinical outcome.4 This classification uses the METAVIR scoring system to stage the degree of fibrosis found on the liver specimens, from no fibrosis as F0 to cirrhosis as F4. F1 to F3 are considered different degrees of fibrosis in the periportal regions to bridging fibrosis between the portal tracts.
Transjugular Liver Biopsy
Thoracic Key
Fastest Thoracic Insight Engine
