High plasma cardiac natriuretic peptides associated with enhanced cyclic guanosine monophosphate production in preascitic cirrhosis

Plasma Cyclic Guanosine Monophosphate Is a Promising Biomarker of Clinically Significant Portal Hypertension in Patients With Liver Cirrhosis

Introduction: Despite intensive research, reliable blood-derived parameters to detect clinically significant portal hypertension (CSPH) in patients with cirrhosis are lacking. As altered homeostasis of cyclic guanosine monophosphate (cGMP), the central mediator of vasodilatation, is an essential factor in the pathogenesis of portal hypertension, the aim of our study was to evaluate plasma cGMP as potential biomarker of cirrhotic portal hypertension. Methods: Plasma cGMP was analyzed in cirrhotic patients with CSPH (ascites, n = 39; esophageal varices, n = 31), cirrhotic patients without CSPH (n = 21), patients with chronic liver disease without cirrhosis (n = 11) and healthy controls (n = 8). cGMP was evaluated as predictor of CSPH using logistic regression models. Further, the effect of transjugular intrahepatic portosystemic shunt (TIPS) placement on plasma cGMP was investigated in a subgroup of cirrhotic patients (n = 13). Results: Plasma cGMP was significantly elevated in cirrhotic patients with CSPH compared to cirrhotic patients without CSPH [78.1 (67.6-89.2) pmol/ml vs. 39.1 (35.0-45.3) pmol/l, p < 0.001]. Of note, this effect was consistent in the subgroup of patients with esophageal varices detected at screening endoscopy who had no prior manifestations of portal hypertension (p < 0.001). Cirrhotic patients without CSPH displayed no significant elevation of plasma cGMP compared to patients without cirrhosis (p = 0.347) and healthy controls (p = 0.200). Regression analyses confirmed that cGMP was an independent predictor of CSPH (OR 1.042, 95% CI 1.008-1.078, p = 0.016). Interestingly, portal decompression by TIPS implantation did not lead to normalization of plasma cGMP levels (p = 0.101). Conclusions: Plasma cGMP is a promising biomarker of CSPH in patients with cirrhosis, especially with respect to screening for esophageal varices. The lacking normalization of plasma cGMP after portal decompression suggests that elevated plasma cGMP in cirrhotic portal hypertension is mainly a correlate of systemic and splanchnic vasodilatation, as these alterations have been shown to persist after TIPS implantation.

[Cirrhotic cardiomyopathy: a specific entity]

Cirrhosis is a frequent and severe condition, which is the late stage of numerous chronic liver diseases. It is associated with major hemodynamic alterations characteristic of hyperdynamic circulation and with a series of structural, functional, electrophysiological and biological heart abnormalities termed cirrhotic cardiomyopathy. The pathogenesis of this syndrome is multifactorial. It is usually clinically latent or mild, likely because the peripheral vasodilatation significantly reduces the left ventricle afterload. However, sudden changes of hemodynamic state (vascular filling, surgical or transjugular intrahepatic porto-systemic shunts, peritoneo-venous shunts and orthotopic liver transplantation) or myocardial contractility (introduction of beta-blocker therapy) can unmask its presence, and sometimes convert latent to overt heart failure. Cirrhotic cardiomyopathy may also contribute to the pathogenesis of hepatorenal syndrome. This entity has been described recently, and its diagnostic criteria are still under debate. To date, current management recommendations are empirical, nonspecific measures. Recognition of cirrhotic cardiomyopathy depends on a high level of awareness for the presence of this syndrome, particularly in patients with advanced cirrhosis who undergo significant surgical, pharmacological or physiological stresses.

The heart and the liver

Cardiac failure affects the liver and liver dysfunction affects the heart. Chronic and acute heart failure can lead to cardiac cirrhosis and cardiogenic ischemic hepatitis. These conditions may impair liver function and treatment should be directed towards the primary heart disease and seek to secure perfusion of vital organs. In patients with advanced cirrhosis, physical and/or pharmacological stress may reveal a reduced cardiac performance with systolic and diastolic dysfunction and electrophysical abnormalities, termed cirrhotic cardiomyopathy. Pathophysiological mechanisms include reduced beta-adrenergic receptor signal transduction and defective cardiac electromechanical coupling. However, the QT interval is prolonged in approximately half of patients with cirrhosis and it may be improved by beta-blockers. No specific therapy can be recommended but it should be supportive and directed against the heart failure. Transjugular intrahepatic portosystemic shunt insertion and liver transplantation affect cardiac function in portal hypertensive patients and cause stress to the cirrhotic heart, with a risk of perioperative heart failure. The risk and prevalence of coronary artery disease are increasing in cirrhotic patients and since perioperative mortality is high, careful evaluation of such patients with dobutamine stress echocardiography, coronary angiography and myocardial perfusion imaging is required prior to liver transplantation. Future research should focus on beneficial effects of treatment on cardiac function and mortality.

Cirrhotic cardiomyopathy

Cirrhotic cardiomyopathy is a recently recognized condition in cirrhosis consisting of systolic incompetence under condition of stress, diastolic dysfunction related to altered diastolic relaxation, and electrophysiological abnormalities in the absence of any known cardiac disease. It can be diagnosed by using a combination of electrocardiograph, 2-dimensional echocardiography, and various serum markers such as brain natriuretic factor. The underlying pathogenetic mechanisms include abnormalities in the beta-adrenergic signaling pathway, altered cardiomyocyte membrane fluidity, increased myocardial fibrosis, cardiomyocyte hypertrophy, and ion channel defects. Various compounds for which levels are elevated in cirrhosis such as nitric oxide and carbon monoxide can also exert a negative inotropic effect on the myocardium, whereas excess sodium and volume retention can lead to myocardial hypertrophy. Various toxins can also aggravate the ion channel defects, thereby widening the QRS complex causing prolonged QT intervals. Clinically, systolic incompetence is most evident when cirrhotic patients are placed under stress, whether physical or pharmacological, or when the extent of peripheral arterial vasodilatation demands an increased cardiac output as in the case of bacterial infections. Acute volume overload such as immediately after insertion of a transjugular intrahepatic portosystemic shunt or after liver transplantation can also tip these cirrhotic patients into cardiac failure. Treatment of cirrhotic cardiomyopathy is unsatisfactory. There is some evidence that beta-blockade may help some cirrhotic patients with baseline prolonged QT interval. Long-term aldosterone antagonism may help reduce myocardial hypertrophy. Future studies should include further elucidation of pathogenetic mechanisms so as to develop effective treatment strategies.

Diagnostic and prognostic impact of brain natriuretic peptide in cardiac and noncardiac diseases

OBJECTIVE

Cardiac secretion of brain natriuretic peptide (BNP) increases with the progression of congestive heart failure (CHF). The plasma measurement of BNP emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of CHF.

METHODS

BNP assay is useful for evaluating patients with acute dyspnea, because a low level can help rule out CHF in primary care settings and reduce the demand for echocardiography. Equally, BNP level can be particularly useful in recognizing heart failure in a patient with acute dyspnea and a history of chronic obstructive pulmonary disease.

RESULTS

However, although the clinical use of BNP as a biomarker in CHF is increasing, the specificity of BNP in CHF is not strong, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Multiple disorders in the intensive care unit, apart from CHF, cause elevated BNP levels, including cardiovascular disease states such as ischemia, arrhythmias, cardiac hypertrophy, and coronary endothelial dysfunction, as well as disorders of no cardiac origin, such as sepsis, septic shock, and acute respiratory distress syndrome. Moreover, the impact of increased BNP in patients with sepsis is not clear. The relationship between BNP and both left ventricular ejection fraction and left-sided filling pressures is weak, and data on the prognostic impact of high BNP levels in patients with sepsis are conflicting.

CONCLUSION

Nevertheless, this review highlights the potential benefits of BNP in the recognition and management of heart failure, and defines the gray zones of BNP levels; it also identifies conditions influencing BNP levels in relation to a certain heart failure and describes conditions of no cardiac origin with increased BNP.

B-type natriuretic peptide: Issues for the intensivist and pulmonologist

OBJECTIVE

B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), although promising as biomarkers for heart failure, are affected by multiple confounders. The purpose of this article is to review the literature on the utility of BNP and NT-proBNP as biomarkers, with a focus on their role in critical illness and pulmonary diseases.

DATA SOURCE

Published articles on BNP and NT-proBNP.

DATA ANALYSIS

Multiple disorders in the intensive care unit cause elevated BNP and NT-proBNP levels, including cardiac diseases, shock, pulmonary hypertension, acute respiratory distress syndrome, acute pulmonary embolism, chronic obstructive pulmonary disease, renal failure, and other conditions.

CONCLUSIONS

Intensivists and pulmonologists should understand that BNP and NT-proBNP levels might be raised to different degrees not only in heart failure but also in critical illness and various pulmonary diseases; in these situations, BNP and NT-proBNP may also serve as markers of severity and prognosis.

Dendroaspis natriuretic peptide in hepatic cirrhosis

OBJECTIVES

Dendroaspis natriuretic peptide (DNP) is a novel peptide that is structurally similar to atrial, brain, and C-type natriuretic peptides. Many natriuretic peptides are increased in hepatic cirrhosis, but the role of DNP in cirrhosis is unknown at present. The aim of the study was to investigate plasma levels of dendroaspis natriuretic-like immunoreactivity in cirrhosis.

METHODS

We measured plasma concentrations of DNP by radioimmunoassay methods in 12 cirrhotic patients without ascites and 44 cirrhotic patients with ascites, and compared these values with 20 age-matched healthy subjects. Renal function, plasma cGMP concentration, plasma renin activity, and plasma endothelin concentration were measured in each patient.

RESULTS

Patients without ascites had circulating levels of DNP similar to those of healthy subjects. By contrast, patients with ascites had increased circulating DNP levels compared to both patients without ascites and healthy subjects. In addition, circulating levels of DNP increased in relation to the severity of cirrhosis. Significant positive correlations were also found between DNP levels, endothelin concentrations, and plasma renin activity.

CONCLUSIONS

The results of this study indicate that plasma DNP is increased in cirrhotic patients with ascites.