Perioperative Plasma Concentrations of Endothelin and Natriuretic Peptides in Children Undergoing Living-Related Liver Transplantation

Biliary Atresia Is Associated With Hypertension

OBJECTIVES

The improved survival of pediatric liver transplant recipients is accompanied by an increase in long-term comorbidities. A recently highlighted concern, hypertension, is associated with chronic kidney disease (CKD) in this population and can result in other target-organ damage during childhood. The prevalence of hypertension in pediatric liver transplantation is imprecisely known. In addition, individual etiologies of liver failure may convey different risks of hypertension. We sought to study the effect of liver transplantation on the prevalence of hypertension and CKD in patients with biliary atresia (BA).

METHODS

We conducted a retrospective chart review of 160 patients with BA followed at the Mount Sinai Medical Center, New York, from 1987 to 2012. Data were accumulated from the initial and subsequent visits at approximately 6 months, 1, 3, 5, 10, and 15 years of age. Hypertension was defined as systolic blood pressure >95th percentile for age, sex, height, and/or use of antihypertensive medication. Renal function was examined over time. Data were stratified by liver transplantation status at the time of visit.

RESULTS

A high prevalence of hypertension was observed from the initial visit through age 10, independent of transplant status (transplanted: 48% initial visit and 13% after 10 years vs nontransplanted: 55% initial visit and 17% after 10 years [P = ns for transplant status]). Mean estimated glomerular filtration rate (eGFR) was lower among liver transplant patients as compared with nontransplant patients and declined posttransplant. The incidence of CKD was higher among transplant patients.

CONCLUSIONS

Hypertension is common among children with BA, independent of liver transplant status. Transplant patients had significantly reduced renal function, which continued to decline over time. Hypertension was not associated with reduced eGFR.

Long-term outcome after liver transplantation

Liver transplantation is a life-saving therapy for patients with end-stage liver disease, acute liver failure, and liver tumors. Over the past 4 decades, improvements in surgical techniques, peritransplant intensive care, and immunosuppressive regimens have resulted in significant improvements in short-term survival. Focus has now shifted to addressing long-term complications and improving quality of life in liver recipients. These include adverse effects of immunosuppression; recurrence of the primary liver disease; and management of diabetes, hypertension, dyslipidemia, obesity, metabolic syndrome, cardiovascular disease, renal dysfunction, osteoporosis, and de novo malignancy. Issues such as posttransplant depression, employment, sexual function, fertility, and pregnancy must not be overlooked, as they have a direct impact on the liver recipient's quality of life. This review summarizes the latest data in long-term outcome after liver transplantation.

Nitric oxide for post-liver-transplantation hypoxemia in pediatric hepatopulmonary syndrome: case report and review

HPS is rare in the pediatric population. Liver transplantation is the ultimate treatment for severe HPS. There are only a few case reports and one series of children in whom HPS was the main indication for liver transplantation. Outcome was good in most of them, with full regression of the pulmonary process. However, hypoxemia in the early post-operative course can have severe consequences, and effective treatment modalities are needed. There are rare instances of the use of iNO for the treatment of post-operative hypoxemia. We describe a 10.5-yr-old boy with severe HPS owing to chronic liver disease after bone marrow transplantation. Liver transplantation from a living related donor (the same sister who donated the bone marrow) was complicated by severe hypoxemia on POD 2. iNO was administered via the ventilator circuit and, after extubation, through nasal prongs. It was slowly tapered down and stopped on POD 10. The child had an otherwise uneventful course and was discharged home on POD 21 with normal oxygen saturation. Liver transplantation should be offered to children with severe HPS. iNO can reverse the hypoxemia that may occur after the operation.

Long-term management of the liver transplant recipient: pearls for the practicing gastroenterologist

Liver transplantation is becoming more common and patients are surviving longer after transplantation. Special care must be paid to the long-term management of these patients because they are at increased risk for medical problems, malignancies, and adverse effects from immunosuppression. A stable and continuing relationship must be developed between the physician and the patient to optimize the long-term outcomes for these individuals.

Overnight Change in Brain Natriuretic Peptide Levels in Children With Sleep-Disordered Breathing

STUDY OBJECTIVES

Obstructive sleep-disordered breathing is accompanied by episodic increases in left ventricle afterload due to large negative swings in intrathoracic pressure and repetitive surges in arterial pressure. Brain natriuretic peptide (BNP) is released by ventricular myocytes in response to pressure and volume overload. It was hypothesized that in children with snoring, overnight change in BNP levels is correlated with severity of disturbance in respiration.

DESIGN

Evening and morning plasma levels of BNP were measured in children with snoring referred for polysomnography.

SETTING

A sleep disorders laboratory in a university hospital.

PARTICIPANTS

Twenty-two children with apnea-hypopnea index (AHI) > or = 5/h (mean +/- SD age, 6.4 +/- 2.5 years), 60 children with AHI < 5/h (mean age, 7 +/- 2.9 years), and 27 control subjects without snoring (mean age, 7.8 +/- 3.7 years) were recruited.

MEASUREMENTS AND RESULTS

Overnight change in BNP (log-transformed ratio of morning-to-evening levels) was larger in children with AHI > or = 5/h, compared to those with AHI < 5/h or to control subjects (0.1 +/- 0.19 vs 0.01 +/- 0.14 vs - 0.06 +/- 0.18; p < 0.05). Children with AHI > or = 5/h had an odds ratio of 4.33 (95% confidence interval, 1.34 to 14) for change in peptide levels > 0.15 relatively to subjects with AHI < 5/h. AHI and oxygen saturation of hemoglobin nadir were significant predictors of overnight change in peptide levels.

CONCLUSIONS

In children with snoring, overnight increase in BNP levels is correlated with severity of disturbance in respiration during sleep, which may indicate presence of nocturnal cardiac strain.

Changes of nitric oxide and endothelin, thromboxane A2 and prostaglandin in cirrhotic patients undergoing liver transplantation

AIM: To investigate the perioperative changes of nitric oxide (NO) and endothelin (ET), thromboxane A₂ (TXA₂) and prostaglandin (PGI₂) during liver transplantation in end-stage liver disease patients.

METHODS: Twenty-seven patients with end-stage cirrhosis undergoing liver transplantation were enrolled in this prospective study. Blood samples were obtained from superior vena at five different surgical stages. Plasma concentrations of nitrate and nitrite were determined to reflect plasma NO levels. Plasma levels of ET-1, 6-keto-PGF1 alpha and thromboxane B₂ (TXB₂), the latter two being stable metabolites of PGI₂ and TXA₂ respectively, were measured.

RESULTS: The NO level decreased significantly after vascular cross-clamping and increased significantly at 30 min after reperfusion. While the ET levels at 30 min after clamping and after reperfusion were significantly elevated. The ratio of NO/ET decreased significantly at 30 min after vascular cross-clamping and at the end of surgery. The PGI₂ level and the TXA₂ during liver transplantation were significantly higher than the baseline level, but the ratio of TXA₂/PGI₂ decreased significantly at 30 min after clamping.

CONCLUSION: NO/ET and TXA₂/PGI₂ change during liver transplantation. Although the precise mechanism remains unknown, they may play a role in the pathobiology of a variety of liver transplant-relevant processes.

Cardiac function in children post-orthotopic liver transplantation: echocardiographic parameters and biochemical markers of subclinical cardiovascular damage

Tacrolimus and cyclosporin A (CsA), the mainstay of preventive therapy for solid organ rejection, may cause various side-effects, such as hypertension and nephrotoxicity. Furthermore, tacrolimus is associated with cardiac hypertrophy. In the immediate post-transplant period, both drugs raise the levels of Endothelin-1 (ET), a potent vasoconstrictor; and of B-type Natriuretic Peptide (BNP), a sensitive marker of left ventricular volume overload, which may precede echocardiographic changes of cardiac dysfunction. The aim of the study was to investigate the presence of cardiac damage, by echocardiography and by the biochemical markers BNP and ET, in post-orthotopic liver transplantation (OLT) children, receiving long-term immunosuppressive therapy. ET (ELISA) and BNP (RIA) were measured in plasma of 18 children, post-OLT and 18 healthy controls. Children post-OLT were echocardiographically assessed for left ventricular mass (interventricular septum and posterior wall dimensions), systolic function (ejection fraction, fractional shortening) and diastolic parameters (mitral valve E and A waves, deceleration time, isovolumic relaxation time). None of the post-transplant recipients had a history or physical examination consistent with cardiac disease and all recipients were normotensive. Echocardiography revealed no systolic or diastolic dysfunction in any of the recipients. The mean ET and BNP levels tended to be higher among children post-liver transplant, compared with healthy controls (ET: 4.22 +/- 5.35 pg/mL vs. 2.1 +/- 2.0 pg/mL; BNP: 7.05 +/- 4.4 pg/mL vs. 5.87 +/- 2.0 pg/mL, respectively, mean +/- s.d.) although differences did not reach statistical significance. Three children (17%) had elevated BNP and/or ET levels. A strong correlation was observed between ET and BNP levels in post-OLT children (r = 0.79, p < or = 0.05). No correlation was found between ET or BNP levels and echocardiographic findings. In children receiving long-term immunosuppressive therapy post-OLT, although cardiac function is grossly preserved, ET and BNP levels tend to be higher than in healthy, age-matched children. Thus, elevated levels of BNP and/or ET may identify patients with early cardiac damage.

Prevention of Renal Impairment by Continuous Infusion of Human Atrial Natriuretic Peptide after Liver Transplantation

BACKGROUND

Acute renal failure occurring immediately after liver transplantation and requiring hemodialysis is a major problem resulting in a poor prognosis. We investigated the efficacy of human atrial natriuretic peptide, which has potent natriuretic effects and unique protective effects for glomeruli in preventing acute renal failure after liver transplantation.

METHODS

Thirty-seven patients who underwent live donor liver transplantation with model for end-stage liver disease scores greater than 15 were the subjects of the study. Subjects were prospectively randomized into two groups: patients that received synthetic human atrial natriuretic peptide infusion (Group H: n=19) and those that received conventional diuretics, furosemide and potassium canrenoate (Group C: n=18). The peri- and postoperative changes in hemodynamic status and renal function were compared between the two groups.

RESULTS

There were no statistical differences in the changes in hemodynamic status between groups. Hemodialysis was required after liver transplantation in nine patients, two in Group H and seven in Group C (P=0.04). Postoperative creatinine clearance was higher in Group H (P=0.03). Aldosterone level was suppressed in group H (P=0.006).

CONCLUSIONS

Continuous infusion of synthetic human atrial natriuretic peptide might be effective for preventing acute renal failure requiring hemodialysis after liver transplantation.

Endothelin activation and postoperative renal failure after human liver transplantation

Renal failure is an established risk factor for impaired patient outcome after orthotopic liver transplantation (OLT). As the endothelin pathway is known to be involved in the development of acute renal failure (ARF), we designed a study to clarify its role in ARF following OLT. Twenty consecutive patients with intact kidney function scheduled for their first OLT were prospectively studied. Plasma big endothelin-1 (ET-1) levels were measured before surgery, after graft reperfusion, and on the first and second postoperative day. According to postoperative glomerular filtration rate (GFR), patients were assigned to the acute renal dysfunction group (ARDF) and the non-ARDF group. Each patient's GFR was estimated according to the 4-variable formula used in the modification of diet in renal disease before surgery, daily within the first postoperative week, and at 1, 3, 12, and 24 months after surgery. Postoperative mean big ET-1 levels correlated significantly with the maximum percent decrease of GFR within 3 days after OLT (P < 0.01). The proportion of patients who developed ARDF was significantly correlated to mean postoperative big ET-1 quartiles (P < 0.01). In the ARDF group, the percent decrease of GFR within 24 months was significantly higher (P < 0.05) as compared to the non-ARDF group. In conclusion, patients who develop ARDF immediately after OLT do not fully recover to baseline regarding long-term kidney function. Short-term GFR was significantly correlated with postoperative big ET-1 plasma levels, suggesting renal dysfunction is mediated by the activated endothelin system.

Cardiac function after orthotopic liver transplantation and the effects of immunosuppression: a prospective randomized trial comparing cyclosporin (Neoral) and tacrolimus

There are several case reports in the literature that describe cardiac complications in the first few weeks after orthotopic liver transplantation (OLT) in patients receiving tacrolimus as their primary immunosuppressive therapy. In this study, we investigated the cardiac function of patients on tacrolimus (T) compared with those on cyclosporin (C) (Neoral; Novartis, Basel, Switzerland) immunosuppression, after OLT, in a prospective randomized trial. We randomized 40 adult patients with cirrhosis to either T or C with azathioprine and prednisolone immunosuppression and followed up on them for 3 months after OLT. All had detailed clinical, biochemical, electrocardiographic and echocardiographic assessments at regular intervals. Abnormalities in cardiac function were common after OLT and significant deterioration in left ventricular diastolic function was demonstrable up to 3 months in both patient groups. Cardiac function was similar in the T and C arms and no significant electrocardiographic differences were observed, although reduced heart rate variability (HRV) and higher mean serum brain natriuretic peptide (BNP) levels were identified in the T group. The percentage increase in posterior wall thickness was higher in the T group. Cardiac dysfunction as shown by worsening echocardiographic measures of left ventricular diastolic function and by clinical cardiac events is common in the first 3 months after OLT in patients with cirrhosis. HRV and BNP values in the T group were worse than in the C group, but this was not translated to an increase in cardiac clinical events in this study.

Perioperative alterations in plasma endothelin-1 and echocardiographic correlates of right heart function

OBJECTIVE

To determine whether greater changes in plasma endothelin-1 (ET-1) concentrations and right ventricular systolic pressure occur after major thoracic surgery than after major abdominal operations.

DESIGN

Prospective study.

SETTING

University hospital.

PARTICIPANTS

Patients undergoing elective thoracotomies (n = 12) or laparotomies (n = 10).

INTERVENTIONS

ET-1 was measured from blood obtained before anesthesia and again on postoperative days 1, 2, 3, and 5 (or 6). Transthoracic echocardiography was performed before surgery and on postoperative day 2 to evaluate right-sided heart function.

MEASUREMENTS AND MAIN RESULTS

After abdominal and thoracic surgery, systemic and estimated pulmonary vascular pressures were normal in both groups and unaffected by surgery. Plasma ET-1 concentrations decreased from baseline values during the first postoperative week with no differences between the groups.

CONCLUSIONS

In patients without organic heart disease, plasma ET-1 levels do not increase in response to major abdominal or thoracic surgery. Whether or not plasma ET-1 concentrations are elevated in patients developing clinically significant postoperative pulmonary hypertension requires further study.

Discoordinate modulation of natriuretic peptides during acute cardiac allograft rejection in humans

BACKGROUND

Increased circulating levels of the cardiac polypeptide hormones atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) may be observed after orthotopic cardiac transplantation. Both the hypertrophic and inflammatory processes in the allograft may contribute to this increase, but no mechanistic explanation has been suggested for this observation.

METHODS AND RESULTS

Plasma immunoreactive ANF and BNP determinations were performed in 10 consecutive transplant patients. These were correlated with degree of rejection as reflected by histopathological findings at serial endomyocardial biopsies. Three patients had associated hemodynamic measurements and blood samples 24 hours before and after transplantation. All rejection episodes that received treatment were accompanied by a marked increase in BNP plasma levels to > approximately 400 pg/mL. Steadily increasing BNP levels preceded overt rejection as assessed by histopathological criteria. The increase in plasma BNP was not always accompanied by an increase in ANF, which suggests the specific upregulation of BNP gene expression during acute rejection episodes. Treatment of the acute rejection episodes led to a substantial decrease of BNP plasma levels.

CONCLUSIONS

The significant selective increase in plasma BNP levels found in the present study has not been previously described. This finding provides a new insight into the mechanism of allograft rejection and the modulation of natriuretic peptide synthesis and release. Furthermore, although preliminary, the data suggest that BNP plasma levels could form the basis for a new, noninvasive screening test to predict acute cardiac allograft rejection. Because treatment with the antilymphocyte monoclonal antibody OKT3 (murine monoclonal antibody to the CD3 antigen of the human T-cell) decreased BNP plasma levels, cytokine production by T-cells may mediate the selective increase in circulating BNP.

New directions in perioperative management for pediatric solid organ transplantation

Advances in pediatric solid organ transplantation have furthered the understanding of end-organ failures and refined the strategies for perioperative management of these otherwise lethal diseases. As the donor pool expands, the number of transplantations increases and long-term survival continues to improve, more complete knowledge of the immunologic and pathologic processes will be gained. A thorough understanding of the principles of transplantation medicine remains essential for physicians to provide optimal perioperative care of pediatric organ transplant patients.

Reversal of hypoxemia by inhaled nitric oxide in children with severe hepatopulmonary syndrome, type 1, during and after liver transplantation

BACKGROUND

The hepatopulmonary syndrome with profound hypoxemia is a rare but severe complication for children with liver cirrhosis. It can be reversed by liver transplantation (LT), which is now regarded as a good indication. However, previous reports have described cases of transient or fatal deteriorations of intrapulmonary shunting after pediatric liver transplantation with dramatically worsening hypoxemia.

METHODS AND RESULTS

A similar case during and after LT in a 4-year-old girl with severe hepatopulmonary syndrome is described with prompt reversal of hypoxemia by inhaled nitric oxide, which was discontinued definitely until day 14 after LT.

CONCLUSIONS

During or after LT, worsening hypoxemia may be improved by using inhaled nitric oxide in pediatric patients undergoing liver transplantation for liver cirrhosis and hepatopulmonary syndrome. The mechanisms are unclear, but may involve mismatching lung ventilation-perfusion. However, additional clinical reports are necessary before accepting these results.