The pathophysiologic basis for the treatment of cirrhotic ascites

Long-term clinical outcome of patients with cirrhosis and refractory ascites treated with transjugular intrahepatic portosystemic shunt insertion

BACKGROUND AND AIM

Transjugular intrahepatic portosystemic shunt (TIPS) is indicated for the treatment of refractory ascites in cirrhosis. The long-term outcome of TIPS for refractory ascites is unknown. The aim of this study is to describe the natural history of patients with refractory ascites post-TIPS, and compare between polytetrafluoroethylene (PTFE)-covered versus bare stents.

METHODS

A retrospective chart review of patients who had TIPS for refractory ascites was conducted. Prospectively collected data include demographics, angiographic data, blood work, and urinary sodium excretion.

RESULTS

There were 136 patients who received TIPS (bare = 104, covered = 32) for over 22 years. Patients with PTFE stents had lower international normalized ratio and model for end-stage liver disease score. More patients with bare stents developed shunt dysfunction (74.0% vs 24.1%, P < 0.0001) and required more TIPS revisions (1.6 ± 0.2/patient vs 0.2 ± 0.1, P < 0.0001). Urinary sodium excretion increased significantly from first month and progressed to 98 ± 9 mmol/day at 12th month post-TIPS (P < 0.001 vs baseline), concurrent with improved renal function. Most patients (77.6%) completely cleared the ascites without diuretics, but many achieved this beyond 2 years. Number of TIPS revision was predictive of complete response at 12 months (odds ratio [OR] 0.7, 95% confidence interval [CI] 0.5-0.9, P < 0.05). Age (hazard ratio [HR] = 1.05 [95% CI 1.02-1.08], P < 0.01), complete response (HR = 0.22 [95% CI 0.12-0.40], P < 0.0001) and polytetrafluoroethylene stents (HR = 0.23 [95% CI 0.05-0.97], P < 0.05) were predictive of survival.

CONCLUSION

TIPS is an effective treatment for cirrhotic refractory ascites. Ascites clearance is dependent on number of TIPS revision, whereas survival is predicted by younger age, complete response, and covered stent use, although era effect likely contributed to improved survival with covered stent use.

Management of refractory ascites

Ascites that does not respond or recurs after high-dose diuresis and sodium restriction should be considered refractory ascites. As cirrhosis advances, the escaping fluid overwhelms the lymphatic return. Decrease in renal plasma flow leads to increased sodium reabsorption at the proximal tubule leading to decreased responsiveness to loop diuretics and mineralocorticoid antagonists, which work distally. These complex hemodynamic alterations lead to refractory ascites. In refractory ascites, high-dose diuresis (400 mg of spironolactone and 160 mg of furosemide) and sodium restriction (<90 mmol/d) result in inadequate weight loss and sub optimal sodium excretion (<78 mmol/d). Further use of diuretics is limited by complications such as encephalopathy, azotemia, renal insufficiency, hyponatremia, and hyperkalemia. Therapy for refractory ascites is limited. The available therapies are repeated large volume paracentesis (LVP), transjugular intrahepatic portosystemic shunts, peritoneovenous shunts, investigational medical therapies, and liver transplantation. LVP with concomitant volume expanders is the initial treatment of choice. Transjugular intrahepatic portosystemic seems to be superior to LVP in reducing the need for repeated paracentesis and improves the quality of life. Several treatments that act at different steps in the pathogenesis of ascites are investigational, and some show promising results. Splanchnic and peripheral vasoconstrictors (Octreotide, Midodrine, and Terlipressin) increase effective arterial volume and decrease activation of the renin-angiotensin system with resultant increase in renal sodium excretion. Clonidine when given with spironolactone has been shown to cause rapid mobilization of ascites by significantly decreasing the sympathetic activity and renin-aldosterone levels. Natural aquaretics and synthetic V2 receptor antagonists (satavaptan) are being evaluated for mobilization of ascites by increasing the excretion of solute-free water. Liver transplantation remains the only definitive therapy for refractory ascites. Because refractory ascites is a poor prognostic sign, liver transplantation should be considered and incorporated early in the treatment plan.

The use of E/A ratio as a predictor of outcome in cirrhotic patients treated with transjugular intrahepatic portosystemic shunt

OBJECTIVES

The clinical significance of diastolic dysfunction in cirrhosis, a feature of cirrhotic cardiomyopathy, is unclear. The aim of this study was to assess the utility of E/A ratio, an indicator of diastolic dysfunction, to predict ascites clearance and mortality after transjugular intrahepatic portosystemic stent shunt (TIPS) insertion.

METHODS

A total of 101 cirrhotic patients who received TIPS had pre-TIPS assessments of demographics, severity of liver dysfunction (Child-Pugh and Model for End-Stage Liver Disease (MELD) scores), renal function, hemodynamics, and cardiac function (two-dimensional echocardiography). An E/A ratio of < or =1 was used to indicate diastolic dysfunction. Patients were followed-up for a mean period of 24.6+/-2.4 months post TIPS.

RESULTS

A total of 41 patients with an E/A ratio of < or =1 (group A), and 60 patients with an E/A ratio of >1 (group B) were studied. Group A had significantly higher MELD scores (14.0+/-1.0 vs. 11.4+/-0.8; P=0.03), because of higher serum creatinine levels (107+/-5 vs. 86+/-6 micromol/l; P<0.01). There was no difference in pre-TIPS systemic hemodynamics, systolic function, or portal pressure between the two groups. After TIPS, more patients in group B had ascites clearance (log rank, P=0.038), and the same patients had a higher probability of survival (log rank, P=0.046). There were three post-TIPS cardiac deaths in group A only. A multivariate analysis showed that an E/A of ratio < or =1 was predictive of slow ascites clearance (hazard ratio=7.3, 95% confidence interval=1.3-40.7, P=0.021) and death after TIPS (hazard ratio=4.7, 95% confidence interval=1.1-20.2, P=0.035).

CONCLUSIONS

Diastolic dysfunction, indicated by reduced E/A ratio, is prevalent in advanced cirrhosis and is associated with reduced ascites clearance and increased mortality post TIPS, possibly related to worsening of hemodynamic dysfunction in the post-TIPS period.

Evaluation and management of patients with refractory ascites

Some patients with ascites due to liver cirrhosis become no longer responsive to diuretics. Once other causes of ascites such as portal vein thrombosis, malignancy or infection and non-compliance with medications and low sodium diet have been excluded, the diagnosis of refractory ascites can be made based on strict criteria. Patients with refractory ascites have very poor prognosis and therefore referral for consideration for liver transplantation should be initiated. Search for reversible components of the underlying liver pathology should be undertaken and targeted therapy, when available, should be considered. Currently, serial large volume paracentesis (LVP) and transjugular intrahepatic portasystemic stent-shunt (TIPS) are the two mainstay treatment options for refractory ascites. Other treatment options are available but not widely used either because they carry high morbidity and mortality (most surgical options) rates, or are new interventions that have shown promise but still need further evaluation. In this comprehensive review, we describe the evaluation and management of patients with refractory ascites from the prospective of the practicing physician.

Renal phosphodiesterase 4B is activated in the Dahl salt-sensitive rat

Reduced beta-adrenoreceptor signaling is associated with increased sympathoadrenal activity in hypertensive patients and animal models of hypertension. However, the mechanism that accounts for this characteristic decline in beta-adrenergic signaling is unclear. In the present study, we investigated renal phosphodiesterase 4B, which metabolizes cAMP. Immunoblot analysis detected only the phosphodiesterase 4B4 isoform present in kidney tissue from spontaneously hypertensive rats, hypertensive Dahl salt-sensitive (SS) rats, and Dahl salt-resistant rats. The phosphorylated (activated) form of the protein was present at 2-fold greater levels in Dahl SS rats than in spontaneously hypertensive rats and Dahl salt-resistant rats, whereas the unphosphorylated form of the protein was reduced by approximately one half in SS animals. In accord with immunoblot data, rolipram-inhibitable cAMP hydrolyzing activity, a measure of PDE4 activity, was approximately 3-fold greater in kidney cytosolic extracts from SS rats than in extracts from spontaneously hypertensive rats and salt-resistant rats. Phosphodiesterase 4B expression was detected by immunohistochemistry in the renal vasculature, proximal tubules, and distal tubules. These results raise the possibility that increased PDE4 activity, specifically phosphodiesterase 4B4 activity, reduces beta-adrenergic signaling in the kidney and contributes to salt-sensitive hypertension in the Dahl SS rat.