Drug interaction between mycophenolate mofetil and rifampin: possible induction of uridine diphosphate-glucuronosyltransferase

The tuberculostatic compound rifampin (INN, rifampicin) induces the expression of a number of drug metabolism-related genes involved in multidrug resistance (P-glycoprotein and multidrug resistance proteins 1 and 2), cytochromes (cytochrome P450 [CYP] 3A4), uridine diphosphate-glucuronosyltransferases, monoamine oxidases, and glutathione S -transferases. Drugs that depend on these enzymes for their metabolism are prone to drug interactions when coadministered with rifampin. A novel, clinically relevant drug interaction is described between rifampin and mycophenolate mofetil (MMF), a cornerstone immunosuppressive molecule used in solid organ transplantation. Long-term rifampin therapy caused a more than twofold reduction in dose-corrected mycophenolic acid (MPA) exposure (dose-interval area under the concentration curve from 0 to 12 hours [AUC 0-12]) when administered simultaneously in a heart-lung transplant recipient, whereas subsequent withdrawal of rifampin resulted in reversal of these changes after 2 weeks of washout (dose-corrected AUC 0-12 after rifampin withdrawal, 19.7 mg.h.L-1.g -1 versus 6.13 mg.h.L-1.g-1 before rifampin withdrawal [221% change]; dose-uncorrected AUC 0-12 after rifampin withdrawal, 29.6 mg.h/L [daily MMF dose, 3 g] versus 18.4 mg.h/L [daily MMF dose, 6 g] during rifampin administration [60.8% change]). Failure to recognize this drug interaction could potentially lead to MPA underexposure and loss of clinical efficacy. The effect of rifampin on MPA metabolism can, at least in part, be explained by simultaneous induction of renal, hepatic, and gastrointestinal uridine diphosphate-glucuronosyltransferases and organic anion transporters with subsequent functional inhibition of enterohepatic recirculation of MPA.

Monitoring of Epstein-Barr viral load in pediatric heart and lung transplant recipients by real-time polymerase chain reaction

BACKGROUND

Elevation in Epstein-Barr virus (EBV) load measured in peripheral blood has been proposed as a marker for development of post-transplant lymphoproliferative disease (PTLD), but there are few published data examining this relationship. We report the longitudinal surveillance of EBV for all recipients of heart (HTx), heart-lung (HLTx) and lung (LTx) transplants at our institution.

METHODS

The study population included all patients transplanted between January 2003 and July 2004. EBV load was serially measured in peripheral blood by real-time polymerase chain reaction (PCR). Results were correlated with recipient pre-transplant EBV status and development of PTLD.

RESULTS

Forty-four transplant operations were performed, including 33 HTx, 6 HLTx and 5 LTx. Thirty-two (73%) of the patients were EBV seropositive pre-transplant. Nineteen (44%) pediatric recipients developed EB viremia, including 17 HTx, 1 HLTx and 1 LTx. Eleven (58%) of these patients were EBV seropositive pre-transplant. EBV was first detected at a median of 30.5 days (range 2 to 81) post-transplant. The median peak EBV load in that group was 10,099 copies/ml (range 5,935 to 255,466) whole blood. One patient with cystic fibrosis post-LTx developed PTLD localized in the colon. This patient was EBV seronegative pre-transplant; peak EBV load was 14,513 copies/ml. Acute infectious mononucleosis was seen in 1 case. Positive pre-transplant EBV status did not predict post-transplant EB viremia (positive predictive value 0.03).

CONCLUSIONS

Contrary to earlier reports, our data demonstrate that a high EBV load does not lead to PTLD early post-transplant. These results do not support the practice of pre-emptively reducing immunosuppression in patients with raised EBV load.

Concomitant upper-lobe bullous emphysema, lower-lobe interstitial fibrosis and pulmonary hypertension in heavy smokers: report of eight cases and review of the literature

INTRODUCTION

Smoking can cause a variety of pulmonary interstitial diseases. Pulmonary fibrosis has traditionally been considered a non-smoking-related disease. Recently, however, evidence of smoking-induced fibrosis has emerged.

SUBJECTS AND METHODS

A group of eight patients from the pulmonary clinic in Rabin Medical Center with a combine presentation of fibrosis and emphysema was identified retrospectively. All patients underwent chest computed tomography and pulmonary function tests. One patient underwent lung-heart transplantation and a complete review of his lung pathology was obtained. Transbronchial biopsy was performed in 3 additional patients and echocardiography was performed to evaluate the pulmonary vasculature.

RESULTS

Upper-lobe emphysema with bulluos changes was found in all patients. In addition, a basal interstitial process was recognized, ranging from ground glass opacities to severe pulmonary fibrosis, with honeycombing. The radiological findings matched the pathological results of combined emphysema and usual interstitial pneumonia. Pulmonary function tests were also in accord, showing severe hypoxemia with mild obstruction, normal-to-mildly reduced lung volumes and a severe decrease in diffusion capacity. Most of the patients had moderate-to-severe pulmonary hypertension as well as diffuse coronary artery disease.

CONCLUSION

Our findings are in line with emerging evidence that the spectrum of interstitial damage caused by smoke includes not only Langerhans cell hystiocytosis, respiratory bronchiolitis or desquamative interstitial pneumonia but also advanced usual interstitial pneumonitis as well. We believe that in some patients smoking plays a destructive role by a variety of mechanisms and can cause emphysema, lung fibrosis as well as pulmonary vasculopathy and hypertension. Future studies are needed to define the genetics and pathophysiology of this uncommonly reported clinical syndrome.

Surgical and Interventional Therapies for Pulmonary Arterial Hypertension

Surgical and interventional therapies for pulmonary arterial hypertension (PAH) in appropriately selected patients have the potential to dramatically improve or, in some cases, cure PAH. These include atrial septostomy, a palliative procedure or bridge to transplantation in patients with refractory right heart failure, pulmonary thromboendarterectomy for pulmonary hypertension associated with chronic thromboembolic disease, and closure of congenital systemic-pulmonary shunts in patients with PAH but without significant pulmonary vascular disease. Lung transplantation should be considered for patients with all forms of PAH who demonstrate advanced or progressive disease.

Reloading the heart: A new animal model of left ventricular assist device removal

OBJECTIVES

Left ventricular assist devices are proposed as a bridge to recovery, but recurrent ventricular deterioration has limited this approach. We describe a new animal model that simulates the effects of left ventricular assist device unloading and then reloading after device removal. The model might facilitate the evaluation of interventions intended to prevent recurrent ventricular dysfunction.

METHODS

The hearts and lungs of Lewis rats were removed and transplanted into the abdomen of recipient rats by anastomosing the donor's ascending aorta to the recipient's abdominal aorta. The transplanted hearts were maintained unloaded for 2 weeks in 49 animals. Eighteen transplanted hearts were removed after 2 weeks of unloading. In 17 animals the donor's right pulmonary artery was anastomosed to the recipient's abdominal aorta to reload the heart for an additional 2 weeks. In 14 animals the hearts were maintained unloaded for 4 weeks (an additional 2 weeks). The unloaded and reloaded hearts were compared with normal rat hearts (n = 18).

RESULTS

In the unloaded hearts the left ventricular end-diastolic pressures remained low. The left ventricular systolic pressures were lower than the aortic pressures. The left ventricular weights (n = 8) and volumes (n = 4) remained significantly lower ( P < .01) than in the normal hearts. Two weeks after reloading, the left ventricular end-diastolic pressure (n = 8) increased ( P < .01), and the ventricle ejected. The left ventricular systolic pressures exceeded the aortic pressures. The left ventricular weights and volumes increased ( P < .01) and approached those of normal hearts. Matrix metalloproteinase 9 (n = 6/group) levels decreased in the unloaded state ( P = .02) and increased back to normal values after reloading.

CONCLUSIONS

This surgical model simulated left ventricular assist device unloading of the left ventricle. The second operation reloaded the left ventricle, which then enlarged. This model will permit the evaluation of adjunctive interventions, such as cell transplantation, intended to facilitate successful left ventricular assist device removal and prevent recurrent dilatation.

Cardiothoracic Surgery after Heart and Heart-Lung Transplantation

OBJECTIVE

We sought to examine our management and the outcomes of cardiothoracic procedures after heart and heart lung transplantation.

METHODS

We performed a retrospective review of cardiothoracic surgical procedures carried out between 1990 and 2004 in patients who had previously undergone heart or heart-lung transplantation at our institution.

RESULTS

Twenty-one out of 340 patients (6.2 %) were identified. Cardiothoracic surgery was performed 44.4 +/- 33 months (range 1 - 115 months) after transplantation. Predominant types of surgery were coronary artery bypass grafting due to allograft vasculopathy (n = 5), aortic surgery due to acute dissection (n = 3), biventricular assist device implantation due to acute rejection (n = 1), tricuspid valve repair (n = 1), multiple cardiac surgical procedures including coronary artery bypass grafting, retransplantation, and tricuspid valve replacement (n = 2), explantation of a functionless heterotopic transplanted heart (n = 1). Lung surgery was performed in six patients due to pneumonia (n = 2), primary lung carcinoma (n = 3), lung torsion following heart-lung transplantation (n = 1). All patients underwent either lobectomy or segmental lung resection. Single lung retransplantation (n = 2) after prior heart-lung transplantation due to bronchiolitis obliterans was performed. In one patient a pneumonectomy (n = 1) due to severe chronic rejection of the contralateral lung was performed. Six subsequent deaths after cardiothoracic procedures were recorded after 1, 4, 78, 163, 205, and 730 days, respectively. Causes of death were advanced carcinoma (n = 1), multi-organ failure due to sepsis (n = 2), sudden heart death (n = 2), and advanced heart failure (n = 1). Fifteen out of 21 patients having undergone cardiothoracic procedures (71.4 %) survived the observation period of 56.6 +/- 34 months (range 1 - 114).

CONCLUSIONS

Reasons for cardiothoracic procedures after prior heart or heart-lung transplantation were allograft vasculopathy, aortic dissections years after transplantation, chronic rejection, and either lung infections or malignancies. Surgical repair can be performed with an acceptable operative risk and good long-term survival rates.

Repair of congenital heart lesions combined with lung transplantation for the treatment of severe pulmonary hypertension: A 13-year experience

OBJECTIVE

In patients with severe pulmonary hypertension associated with congenital heart disease, we prefer to perform repair of the congenital heart disease and lung transplantation whenever feasible so as to augment the donor pool and avoid the cardiac complications associated with heart transplantation. We report our experience with repair of congenital heart disease and lung transplantation and compare the results with those of patients who underwent heart-lung transplantation during the same period.

METHODS

The records of patients who had repair of congenital heart disease and lung transplantation (n = 35) and heart-lung transplantation (n = 16) between 1990 and 2003 were reviewed.

RESULTS

The underlying congenital heart disease in the repair of congenital heart disease and lung transplantation group included transposition of great vessels (n = 2), atrioventricular canal defect (n = 2), ventricular septal defect (n = 9), pulmonary venous obstruction (n = 7), scimitar syndrome (n = 2), pulmonary arterial atresia or stenosis (n = 5), and others (n = 8). Thirteen of the patients undergoing repair of congenital heart disease and lung transplantation (37.1%) had the congenital heart disease repaired before lung transplantation; the remaining congenital heart disease repairs were performed concurrently with transplantation. Sixteen patients underwent heart-lung transplantation because of poor left ventricular function or single-ventricle anatomy. Freedoms from bronchiolitis obliterans at 1, 3, and 5 years were 72.9%, 54.7%, and 54.7% for the repair of congenital heart disease and lung transplantation group and 77.8%, 51.9%, and 38.9% for the heart-lung transplantation group, respectively. Survivals at 1, 3, and 5 years were 62.9%, 51.4%, and 51.4% for the repair of congenital heart disease and lung transplantation group and 66.5%, 66.5%, and 60% for the heart-lung transplantation group, respectively.

CONCLUSION

Repair of congenital heart disease and lung transplantation is a feasible treatment option. Long-term outcome is determined by associated complications related to lung transplantation. Despite the complexity of combined congenital heart disease repair with lung transplantation and the resulting perioperative morbidity, the patients had similar outcomes to those of patients who underwent heart-lung transplantation.

Heart-lung transplantation in Korea

Heart-lung transplantation is an effective treatment for patients with various forms of congenital heart disease or pulmonary hypertension. Since the first heart-lung transplantation in 1997, five transplants have been performed in Korea. Three cases were performed in 1997, one in 1998, and the latest one in 2002. The preoperative diagnoses were complex congenital heart disease (CHD) in 2, and CHD with Eisenmenger's syndrome in 3. In this paper, we report five cases of heart-lung transplantation performed in Korea, and include a review of the relevant literature.

Thoracic transplantation and stem cell therapy

Lung and heart transplantations are accepted standard therapies for end stage diseases and will maintain their importancy in the future. Potentially, transplantation at a cellular level using various forms of stem cells becomes an additional therapeutic approach.

Anesthetic management of the pediatric patient undergoing solid organ transplantation

Solid organ transplantation is now routinely performed at many institutions. Pediatric organ recipients present difficult challenges to pediatric anesthesiologists. Physiologic, anatomic, and pharmacologic derangements in this population may make both the surgical procedure and the anesthetic management complicated. This article presents an overview of the unique problems and the strategies to solve them in this population.

Hypertension as a marker for later development of end-stage renal failure after lung and heart-lung transplantation: A cohort study

BACKGROUND

Time to renal failure after transplantation is not well known and the prognosis of lung and heart-lung transplantation with respect to end-stage renal failure and related factors has not been investigated in detail. We determined the predictors of end-stage renal failure after lung or heart-lung transplant using multivariate analysis.

METHODS

A cohort study of 115 adult patients transplanted between 1990 and 1995, who survived at least 5 years, was carried out. Characteristics and clinical findings, including blood pressure, creatinine clearance and immunosuppression levels of patients with end-stage renal failure, were compared with those without, initially in a univariate analysis. Then a multivariate logistic regression model was built to examine the association of predictor variables with end-stage renal failure after adjustment for confounding.

RESULTS

There were 19 of 115 (16.4%) patients with end-stage renal failure, with an average time of loss of renal function of 7.6 years (95% confidence interval [CI] 6.5 to 8.7) after transplantation. There was no difference in survival between patients with end-stage renal failure and those without. Multivariate analysis showed that development of hypertension post-operatively was the only significant predictor variable (odds ratio 8.16, 95% CI 1.01 to 66.0, p = 0.04). Patients' age at transplantation, gender, underlying medical conditions and other post-transplant features were not associated with end-stage renal failure.

CONCLUSIONS

Development of hypertension after lung or heart-lung transplant should be used a marker for later development of end-stage renal failure. Any hypertension should be treated energetically. Acute renal failure immediately post-operatively did not predict end-stage renal failure in this cohort of patients.

Airway anastomosis complications in de novo lung transplantation with sirolimus-based immunosuppression

A prospective, pilot trial was started to evaluate the effect of a sirolimus-based immunosuppressive regimen on acute and chronic rejection in de novo lung transplant patients. Primary lung transplant (LTx) recipients received a sirolimus- and tacrolimus-based immunosuppressive therapy immediately after transplantation. Both immunosuppressants were administered with trough level adjusted, while steroid administration was minimized. Four patients were enrolled (2 single-lung transplants, 1 double-lung transplant, 1 heart-lung transplant) in the study. Mean ischemia time was 387 +/- 92 minutes. Acute rejection (at least Grade A1 ISHLT) was detected in 1 patient. Incidence of infection was 0.6 infection per 100 patient-days (3 Aspergillus infections). Until hospital discharge mean sirolimus trough level was 6.2 +/- 1.2 ng/ml. Depending upon mean sirolimus trough levels of each patient, severe wound-healing complications were seen in 3 patients, resulting in bronchial airway dehiscence in 2 patients with lethal outcome in 1 patient. As a result of these complications, we revised the study design after inclusion of only 4 patients: Sirolimus administration is now started after completion of bronchial wound-healing. Sirolimus-based immunosuppressive therapy administered immediately after lung transplantation seems to be associated with severe wound-healing complications of the bronchial anastomosis.

Chylothorax after heart/lung transplantation

Chylothorax is a potentially serious complication of lung and heart-lung transplantation. This article describes the clinical course of chylothorax in 3 heart-lung allograft recipients. We discuss management options, including dietary modifications, octreotide infusion, thoracic duct ligation and embolization, and surgical pleurodesis. In addition, we describe the novel use of aminocaproic acid to reduce lymph flow. We propose a multidisciplinary approach for the management of chylothorax that includes both medical and surgical options.

Recurrent fatal pulmonary alveolar proteinosis after heart-lung transplantation in a child with lysinuric protein intolerance

We present a case of recurrent pulmonary alveolar proteinosis after heart-lung transplantation in a child with lysinuric protein intolerance. The recurrence of the pulmonary disease provides further insight regarding the possible pathogenesis of pulmonary alveolar proteinosis and therapeutic options for this complication.

Interventional and surgical modalities of treatment for pulmonary arterial hypertension

Beyond medical therapy, different interventional and surgical approaches exist for treatment of pulmonary arterial hypertension (PAH). Atrial septostomy has been applied in patients with lack of response to medical therapy in the absence of other surgical treatment options. With growing experience, procedure-related death rates have been reduced to 5.4%, and the most suitable patient group has been identified among patients with a mean right atrial pressure between 10 and 20 mm Hg. Pulmonary endarterectomy is the accepted form of treatment for patients with chronic thromboembolic pulmonary hypertension. Establishing the diagnosis and the classification of the type of lesions by pulmonary angiography is crucial for optimal patient selection. Perioperative mortality rates have been reduced to <10% in experienced centers, and the hemodynamic improvement is dramatic and sustained. Lung and heart-lung transplantation remains the procedure of choice for patients unsuitable for other treatment modalities. Timing of the procedure is difficult because waiting times vary between centers and usually are in a high range. Early referral of patients unresponsive to other treatment forms is therefore of importance to avoid transplantation of patients with established significant comorbidity. The survival rate during the first five years after transplantation for PAH is intermediate among the lung diseases, lower than chronic obstructive pulmonary disease but higher than idiopathic pulmonary fibrosis.

Role of Transbronchial Biopsies in Pediatric Lung Diseases

STUDY OBJECTIVE

To evaluate the role of transbronchial biopsies (TBBs) in pediatric lung diseases.

DESIGN AND METHODS

We reviewed the records of TBBs performed in pediatric patients at the University of Florida between July 1996 and August 2003. The sample adequacy, diagnostic utility, and procedural complications of the two types of bronchoscopy apparatuses used to collect the samples were assessed and compared.

PATIENTS

A total of 429 TBB procedures were performed in 46 patients (age range, 2 months to 21 years) who had received a heart-lung or lung transplant and in 38 non-lung transplant patients (age range, 2 weeks to 18 years). For 86 procedures, the pediatric bronchoscope and forceps that fit in a 1.2-mm channel were used, and a small adult bronchoscope and 2.0-mm forceps were used for the remaining procedures.

RESULTS

Adequate tissue samples were obtained in 85% of the procedures using a pediatric bronchoscope and in 97% using an adult bronchoscope. In the non-lung transplant patients, the biopsy findings were considered to be diagnostic in 58% of all procedures (adult bronchoscope, 64%; and pediatric bronchoscope, 50%), contributory in 21%, and noncontributory in 21%. In the lung transplant patients, treatable acute cellular rejection was diagnosed in 24% of the surveillance TBBs and in 47% of the TBBs performed as a result of clinical symptoms. Complications included five pneumothoraces and five episodes of excessive bleeding requiring the discontinuation of the procedure in three of the cases.

CONCLUSIONS

Adequate lung tissue for histologic diagnosis can be obtained safely and effectively from pediatric patients of all ages via flexible bronchoscopy with TBB. The performance of bronchoscopy should be considered based on clinical indications, rather than on the age or size of the patient, when a tissue diagnosis is needed. When feasible, the use of an adult bronchoscope is preferable due to the higher diagnostic yield.

Surgical Treatments/Interventions for Pulmonary Arterial Hypertension

While considerable advances have been achieved in the medical treatment of pulmonary arterial hypertension (PAH) over the past decade, surgical and interventional approaches continue to have important roles in those patients for whom medical therapy is unavailable or has been unsuccessful. These techniques include pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension, thoracic transplantation, and atrial septostomy. This chapter will provide evidence-based recommendations for the selection and timing of surgical and interventional treatments of PAH for physicians involved in the care of these complex patients.