Complications of endomyocardial biopsy in children

Potential of the Right Ventricular Endomyocardial Biopsy to Diagnose and Assist in the Management of Congestive Heart Failure: Insights From Recent Clinical Trials

In the United States congestive heart failure is most commonly due to ischemic cardiomyopathy, but nonischemic causes of cardiomyopathy can also result in congestive heart failure. Indeed, nonischemic dilated cardiomyopathy affects approximately 100,000 persons in the United States and is responsible for 45% of heart transplants. Although these patients undergo thorough cardiovascular evaluation, a specific cause is usually not found. Endomyocardial biopsy may yield diagnostic and prognostic information in this setting, and there has been a renewed interest in the use of endomyocardial biopsy in the evaluation of specific subsets of patients with congestive heart failure to identify potentially treatable myocarditides. However, the role of endomyocardial biopsy in the evaluation of patients with nonischemic cardiomyopathy is ill defined. In this review, the authors discuss the latest data on the risks and the utility of endomyocardial biopsy in the management of heart failure in the setting of dilated cardiomyopathy and specific myocarditides. Gaps in present knowledge and the obstacles to research in this area are identified.

Efficacy of signal-averaged electrocardiography in the young orthotopic heart transplant patient to detect allograft rejection

Endomyocardial biopsy is the gold standard survey for cardiac graft rejection. Signal-averaged electrocardiography (SAECG) identifies slowly conducting, diseased myocardium. We sought to determine whether SAECG is a sensitive, noninvasive transplant surveillance method in the young.Ninety-four SAECGs recorded prior to biopsy in 20 young transplant (OHT) patients and those from 15 healthy age-matched controls (CTL) were analyzed. In the OHT group, 56 no-rejection (NOREJ) (ISHLT grades 0 or 1 A) and 37 acute rejection (REJ) (ISHLT grades IB, 2, and 3A) SAECGs were compared, SAECGs were filtered at 40-255 Hz. Total QRS duration (QRSd), duration of terminal low amplitude of QRS under 40 microV (LAS), and root mean square amplitude of terminal 40 msec of QRS (RMS40) were compared.SAECGs were significantly different in CTL vs NOREJ but not in NOREJ vs REJ: QRSd, 81.7 +/- 8, 107.2 +/- 18.4, and 112.3 +/- 21.6 msec, respectively; LAS, (18 +/- 5.8, 23.6 +/- 10.7, and 27 +/- 14.8 msec, respectively; and RMS40, (169.3 +/- 100.4, 68 +/- 48.8, and 57.5 +/- 45.6 microV, respectively. Children following OHT exhibited significant differences in the SAECG compared to controls. Differences between the NOREJ and REJ groups were negligible. Therefore, SAECG may not be effective in detecting OHT rejection in the young.

Heart and lung transplantation in children

During the past two decades, several advances have resulted in marked improvement in medium-term survival for infants and children undergoing heart transplantation. Unfortunately, progress has been less dramatic in the field of lung and heart-lung transplantation, where there is little evidence of improved outcomes. The procedures remain palliative and all transplant recipients are at risk for the adverse effects of non-specific immunosuppression, including infections, lymphoproliferative disorders, and non-lymphoid malignancies. In addition, current immunosuppressive agents have narrow therapeutic windows and exhibit a wide array of organ toxicities, posing special challenges for the young patient who must endure life-long immunosuppression. New immunosuppressive regimens have lowered the rates of acute rejection but appear to have had relatively little impact on the incidence of chronic rejection, the principal cause of late graft loss. The ultimate goal is to induce a state of donor-specific tolerance, wherein the recipient will accept the allograft indefinitely without the need for long-term immunosuppression. This quest is currently being realised in animal models of solid organ transplantation, and offers great hope for children undergoing heart and lung transplantation in the future.

Emergent use of extracorporeal membrane oxygenation during pediatric cardiac catheterization

OBJECTIVES

The goal of this study was to evaluate the utility of extracorporeal membrane oxygenation (ECMO) to resuscitate patients following critical cardiac events in the catheterization laboratory.

DESIGN

Retrospective review of medical records.

SETTING

Cardiac intensive care unit and cardiac catheterization laboratory at a tertiary care children's hospital.

PATIENTS

Pediatric patients cannulated emergently for ECMO in the cardiac catheterization laboratory (n = 22).

INTERVENTIONS

ECMO was initiated emergently in the cardiac catheterization laboratory for progressive hemodynamic deterioration due to low cardiac output syndrome or catheter-induced complications.

MEASUREMENTS AND MAIN RESULTS

Twenty-two patients were cannulated for ECMO in the catheterization laboratory between 1996 and 2004. Median age was 33 months (range 0-192), median weight 14.8 kg (2.4-75), and median duration of ECMO 84 hrs (2-343). Indications included catheter-induced complication (n = 14), severe low cardiac output syndrome (n = 7), and hypoxemia (n = 1). Three patients (14%) were cannulated in the catheterization laboratory before catheterization for low cardiac output or hypoxemia. During cannulation, 19 patients (86%) were receiving chest compressions; median duration of cardiopulmonary resuscitation was 29 mins (20-57). Eighteen patients (82%) survived to discharge (five of whom underwent cardiac transplantation) and four (18%) died. Of 19 patients who received cardiopulmonary resuscitation during cannulation, 15 (79%) survived to discharge and nine (47%) sustained neurologic injury. There was no significant difference between survivors and nonsurvivors in age, weight, duration of cardiopulmonary resuscitation or ECMO support, pH, or lactate levels.

CONCLUSIONS

ECMO is a technically feasible and highly successful tool in the resuscitation of pediatric patients following critical events in the cardiac catheterization laboratory.

Outcome of acute fulminant myocarditis in children

OBJECTIVES

To highlight clinical features and outcome of acute fulminant myocarditis (AFM) in children.

METHODS

Diagnostic criteria were (1) the presence of severe and acute heart failure; (2) left ventricular dysfunction on echocardiography; (3) recent history of viral illness; and (4) no history of cardiomyopathy.

RESULTS

Eleven children were included between 1998 and 2003, at a median age of 1 (0 to 9) year. Their mean left ventricular ejection fraction (LVEF) was 22 (SD 9)% at presentation. A virus was identified in five patients: human parvovirus B19 (n = 2), Epstein-Barr (n = 1), varicella zoster (n = 1), and coxsackie (n = 1). The median intensive care unit course was 13 (2-34) days. Intravenous inotropic support was required by nine patients and eight were mechanically ventilated. All patients received corticosteroid, associated with intravenous immunoglobulin in seven. Five patients experienced cardiocirculatory arrest that was successfully resuscitated in four. At a median follow up of 58.7 (33.8-83.1) months, the 10 survivors are asymptomatic with normalised LVEF.

CONCLUSION

Despite a severe presentation, the outcome of AFM is favourable. Aggressive symptomatic management is warranted and heart transplantation should be considered only when maximal supportive therapy does not lead to improvement.

Early Experience with Real-Time Three-Dimensional Echocardiographic Guidance of Right Ventricular Biopsy in Children

BACKGROUND

Right ventricular endomyocardial biopsy is the gold standard for detecting active myocardial inflammation in cardiomyopathy as well as rejection after cardiac transplantation. This procedure has historically required the exclusive use of fluoroscopic guidance to guide catheter, sheath, and bioptome manipulation. The current study evaluates the feasibility and utility of real-time transthoracic three-dimensional echocardiography (3DE) to guide right ventricular endomyocardial biopsies in children.

METHODS

From July 2003 to April 2004, we utilized real-time 3DE in 28 consecutive cardiac catheterizations in children aged 18 months to 16 years who were undergoing endomyocardial biopsy. A commercially available 3DE scanner (Philips Sonos 7500) equipped with a 2-4 MHz 3D matrix array transthoracic probe was utilized in all cases.

RESULTS

A total of 123 endomyocardial biopsy samples were obtained in nine patients (BSA 0.85 m(2)+/- 0.33 m(2)). Of these 123 samples, 99 (80%) were obtained with the use of real-time transthoracic 3DE. There were no complications, including no new tricuspid valve leaflet flail or pericardial effusion. 3DE proved to be a reliable noninvasive modality to properly direct the bioptome to the desired site of biopsy within the right ventricle. As familiarity with this technique increased, the need for fluoroscopic guidance of bioptome manipulation in the right ventricle was minimized.

CONCLUSIONS

The use of real-time transthoracic 3DE in endomyocardial right ventricular biopsies in children is both feasible and safe. Further study to determine the impact of real-time 3DE guidance on fluoroscopy and case times for endomyocardial biopsies is warranted.

Endomyocardial biopsy for non-transplant-related disorders

Endomyocardial biopsy (EMB) remains the "gold standard" for diagnosing rejection after cardiac transplantation. In addition, it has value in monitoring patients during treatment with doxorubicin. It also is important in the setting of acute-onset heart failure for the diagnosis of myocarditis, particularly giant cell myocarditis because earlier transplantation usually is undertaken in patients with giant cell morphologic features. EMB has a role in the unexplained cardiomyoapthy for excluding specific disease processes that might lead to similar morphofunctional changes but might be reversible or a contraindication for transplantation. This review focuses on the growing number of diseases that can be diagnosed by EMB in adult and pediatric age groups.

Therapy for pediatric myocarditis

Pediatric myocarditis is most often associated with the acute or subacute onset of congestive heart failure in a previously healthy child. Myocarditis presenting with acute, severe symptomatology, termed fulminant myocarditis, has a high rate of recovery. Aggressive supportive care is indicated in fulminant myocarditis, including mechanical circulatory support. For subacute heart failure, supportive care remains the mainstay of therapy for myocarditis. A number of uncontrolled pediatric studies using both immunosuppressive therapy and/or immunomodulating therapy with intravenous gamma globulin have suggested these therapies are safe and useful in treating pediatric myocarditis. However, translating these results into recommended, routine therapy for pediatric myocarditis is complicated by the high rate of spontaneous improvement of myocarditis with supportive care, and the lack of demonstrable benefit for immunosuppressive and immunomodulating therapies in blinded, randomized, placebo-controlled trials in adult myocarditis. Heart transplantation remains the final therapeutic option for children with myocarditis and intractable severe heart failure.

The economic implications of noninvasive molecular testing for cardiac allograft rejection

Endomyocardial biopsy is the mainstay for monitoring cardiac allograft rejection. A noninvasive strategy--peripheral blood gene expression profiling of circulating leukocytes--is an alternative with proven benefits, but unclear economic implications. Financial data were obtained from five cardiac transplant centers. An economic evaluation was conducted to compare the costs of outpatient biopsy with those of a noninvasive approach to monitoring cardiac allograft rejection. Hospital outpatient biopsy costs averaged 3297 US dollars, excluding reimbursement for professional fees. Costs to Medicare and private payers averaged 3581 US dollars and 4140 US dollars, respectively. A noninvasive monitoring test can reduce biopsy utilization. The savings to health care payers in the United States can be conservatively estimated at approximately 12.0 million US dollars annually. Molecular testing using gene expression profiling of peripheral circulating leukocytes is a new technology that offers physicians a noninvasive, less expensive alternative to endomyocardial biopsy for monitoring allograft rejection in cardiac transplant patients.

Cardiac troponin T: a marker in the diagnosis of acute myocarditis in children

This study was conducted to assess the use of serum cardiac troponin T (cTnT) level as a noninvasive indicator to diagnose acute myocarditis in children. Noninvasive conventional methods often fail to diagnose myocarditis, A median cTnT level of 0.088 ng/ml (0.04-3.11) was reported in pediatric patients with acute myocarditis in our previous study. Hence, we attempted to determine the cutfoff level of cTnT to diagnose acute myocarditis in children. Pediatric patients with clinically suspected myocarditis or dilated cardiomyopathy (DCM) and a control group were recruited. History, physical examination, elctrocardiogram, chest roentgenogram, echocardiogram, cTnT level, and/or endomyocardial biopsy and clinical course were studied. The gold standard to diagnose acute myocarditis was endomyocardial biopsy proved according to the Dallas criteria and/or recovery from cardiovascular problems within 6 months of follow-up. Forty-three patients were admitted due to cardiovascular problems from primary myocardial dysfunction. Twenty-four patients were diagnosed as acute myocarditis (group 1), 19 were idiopathic chronic DCM (group 2), and 21 patients had moderate to large ventricular septal defect and congestive heart failure (group 3). Median cTnT level was statistically higher in (group 1) compared to groups 2 and 3. Ejection fraction (EF) and left ventricular end diastolic dimension (LVEDd) z score of acute myocarditis were 38.5% (range, 21-67) and 1.3 (range, -0.8-3.0), respectively, which were significantly better than DCM [28.0% (range, 17-45) and 6.0 (range, 2.0-10.0)]. The cutoff point of cTnT level to diagnose acute myocarditis was 0.052 ng/ml (sensitivity, 71%; specificity, 86%). cTnT level, EF, and LVEDd z score did not predict short-term outcomes of patients. In acute myocarditis, cTnT level and EF were significantly higher and LVEDd z score was significantly lower than in DCM. However, the three parameters had no significant effect on outcomes of the patients. Our data show that cardiac a cTnT level of 0.052 ng/ml is an appropriate cutoff point for the diagnosis of acute myocarditis.

Detection of Cardiac Allograft Rejection and Response to Immunosuppressive Therapy With Peripheral Blood Gene Expression

BACKGROUND

Assessment of gene expression in peripheral blood may provide a noninvasive screening test for allograft rejection. We hypothesized that changes in peripheral blood expression profiles would correlate with biopsy-proven rejection and would resolve after treatment of rejection episodes.

METHODS AND RESULTS

We performed a case-control study nested within a cohort of 189 cardiac transplant patients who had blood samples obtained during endomyocardial biopsy (EMB). Using Affymetrix HU133A microarrays, we analyzed whole-blood expression profiles from 3 groups: (1) control samples with negative EMB (n=7); (2) samples obtained during rejection (at least International Society for Heart and Lung Transplantation grade 3A; n=7); and (3) samples obtained after rejection, after treatment and normalization of the EMB (n=7). We identified 91 transcripts differentially expressed in rejection compared with control (false discovery rate <0.10). In postrejection samples, 98% of transcripts returned toward control levels, displaying an intermediate expression profile for patients with treated rejection (P<0.0001). Cluster analysis of the 40 transcripts with >25% change in expression levels during rejection demonstrated good discrimination between control and rejection samples and verified the intermediate expression profile of postrejection samples. Quantitative real-time polymerase chain reaction confirmed significant differential expression for the predictive markers CFLAR and SOD2 (UniGene ID No. 355724 and No. 384944).

CONCLUSIONS

These data demonstrate that peripheral blood expression profiles correlate with biopsy-proven allograft rejection. Intermediate expression profiles of treated rejection suggest persistent immune activation despite normalization of the EMB. If validated in larger studies, expression profiling may prove to be a more sensitive screening test for allograft rejection than EMB.

Epicardial and microvascular graft vessel disease in children

AIM

Graft vessel disease (GVD) is one of the main limiting factors to long-term survival after adult heart transplantation (HTx). The incidence of epicardial and microvascular GVD in paediatric patients was studied.

METHODS

A total of 137 coronary angiographies from 130 paediatric HTx and heart and lung transplant (HLTx) patients (70 male, 60 female, aged 0-18 y) were evaluated according to the Stanford classification and its supplements (minor vessel alterations). In H&E stainings from right ventricular endomyocardial biopsies (EMB = 397), light microscopic diagnosis of acute cellular rejection (ISHLT classification) and vascular reaction (morphology of endothelial cells and vessel walls) was performed.

RESULTS

Moderate rejection was present in 32.8% and severe rejection in 13.3% of EMB. Microvascular EC swelling was found in 33.5% and vessel wall thickening in 53.8% of EMB. The results of the coronary angiographic investigations were: Stanford lesions = 61.2%, peripheral obliterations = 52.5%, diameter fluctuations = 86.3%, pathologic tapering = 64.0%, calcifications = 10.8%. Long-term survivors (> or =5 y) showed macrovascular alterations in 78% of cases and microvascular alterations in 67% of cases.

CONCLUSION

The development of micro- and macrovascular GVD is one of the predominant complications in long-term survivors after paediatric HTx and HLTx.

Immunosuppressive therapy in acute myocarditis: an 18 year systematic review

BACKGROUND

Immunosuppressive therapy is reportedly ineffective in adults with acute myocarditis.

AIMS

To systematically review the impact of immunosuppressive therapy on the outcome of acute myocarditis in children.

METHODS

A literature search for articles published from 1984 to 2003 was conducted with the following keywords: myocarditis, dilated cardiomyopathy, and immunosuppression. The relevant studies were systematically reviewed and comparison of treatment effect was made by calculating the odds ratio (OR) and confidence interval (CI) using the exact method based on the exact discrete reference distribution.

RESULTS

Of the 1470 articles found, only nine studies were eligible. The odds for improvement with immunosuppression was between 4.33 (95% CI 0.52 to 52.23) and 2.7 (95% CI 0.59 to 14.21). Addition of a second immunosuppressive agent to prednisolone only proved effective in one randomised controlled trial (OR 0.09, 95% CI 0.01 to 0.52). Heterogeneity of these studies precluded pooled odds ratio.

CONCLUSION

Current data suggest that immunosuppressive therapy does not significantly improve outcomes in children with acute myocarditis and there is insufficient evidence for its routine use. However, statistical power to detect a significant difference in the treatment effect may be limited because of the small number of subjects. This, together with problems of diagnosis, varying treatment practices, and a relative lack of evidence based guidelines would support efforts for a large multicentre, randomised controlled trial to better define the role of immunosuppression in acute myocarditis.

Advances in methods for surveillance of rejection

Transplantation is an effective treatment modality for infants1 and children2 with end-stage cardiac diseases. Rejection remains a major complication (Figure 1), even in newborn infants.3 Acute rejection can best be operationally defined by clinical findings, histopathology, and/or abnormalities of ventricular function of new origin that require, and respond to, intensified immunosuppression. Mechanistically, the ability to detect acute rejection is critically dependent on the detection of significant new myocytic injury, damage, and/or death. Surveillance for rejection is critically important in determining both long and short-term outcomes following cardiac transplantation. The ideal strategy for surveillance should have a high negative predictive value, correctly identifying the absence of myocytic injury, with high specificity, such that it does not falsely predict such injury.4

The yield of surveillance endomyocardial biopsies as a screen for cellular rejection in pediatric heart transplant patients

Endomyocardial biopsy is commonly used to screen for cellular rejection in pediatric heart transplant patients. The yield of EMBs when combined with newly developed immunohistochemical techniques and modern immunosuppression in pediatric heart transplant patients is unknown. After OHT, surveillance biopsies were performed on a routine basis on all pediatric patients. EMBs were also performed on symptomatic OHT patients suspected to have rejection. All positive results (greater than ISHLT grade 1B) were confirmed with immunohistochemical staining. A retrospective review of consecutive EMBs performed in this institution from January 1995 to January 2003 was performed. The echocardiographic results, clinical history and treatment changes at the time of every biopsy were also catalogued. Of the 1093 EMB results from 136 pediatric heart transplant grafts (127 patients, 64 male) reviewed, 825 biopsies were performed on patients managed with tacrolimus and 268 were performed on patients managed with cyclosporine. The patients managed with tacrolimus had an incidence of 0.85% (7/825) for significant rejection (greater than ISHLT grade 1B rejection) vs. an incidence of 4.1% (11/268) for the patients on cyclosporine (p < 0.0005). In the asymptomatic tacrolimus patients, only two screening biopsies (0.26%) manifest significant rejection, and both of these were performed within the first month after transplantation. Of the symptomatic tacrolimus patients, 9.1% (n = 5) had findings on biopsy consistent with significant cellular rejection. There were 25 patients with grade 1B rejection. Twenty-two of these patients were not treated, and all cases of grade 1B rejection resolved without clinical sequelae. For pediatric patients more than 30 days after OHT, EMB has failed to reveal significant episodes of cellular rejection in asymptomatic patients managed with tacrolimus.

Pediatric heart and lung transplantation

During the last two decades, several advances have resulted in marked improvement in medium-term survival with excellent quality of life in pediatric heart transplant recipients. These were possible due to better donor and recipient selection, increased surgical experience in transplantation for complex congenital heart disease, development of effective rejection surveillance, and wider choice of immunosuppressive medications. Despite all of these advances, recipients suffer from the adverse effects of non-specific immunosuppression including infections, post-transplant lymphoproliferative disorders and other malignancies, renal dysfunction and other important end-organ toxicities. Furthermore, newer immunosuppressive regimens appear (so far) to have had relatively little impact on the incidence of allograft coronary vasculopathy (chronic rejection). Progress in our understanding of the immunologic mechanisms of rejection and graft acceptance should lead to more targeted immunosuppressive therapy and avoidance of non-specific immunosuppression. The ultimate goal is to induce a state of tolerance, wherein the recipient will accept the allograft indefinitely without the need for long-term immunosuppression and yet remain immunocompetent to other antigens. This quest is currently being realized in many animal models of solid organ transplantation and offers great hope for the future.

A formidable challenge: the diagnosis and treatment of viral myocarditis in children

It is generally well accepted that one third of patients with viral myocarditis experience a complete recovery of normal cardiac function, one third improve clinically but show residual cardiac dysfunction, and one third experience chronic heart failure and die or require heart transplantation. It is hoped that a better understanding of the underlying cause and pathogenesis of this disease will increase the number of patients who experience a complete recovery. New advances in both the diagnosis and treatment of viral myocarditis continue to enter clinical practice at a rapid pace, and it is likely that a genomic approach to the diagnostic evaluation and treatment of this disease will become possible in the near future. Viral myocarditis, however, will remain a significant diagnosticand therapeutic challenge to both physicians and scientists alike.

Clinical outcomes and utility of cardiac catheterization prior to superior cavopulmonary anastomosis

OBJECTIVES

We sought to characterize the outcomes of routine catheterization prior to superior cavopulmonary anastomosis and to determine if some patients were unlikely to benefit from catheterization and thus might be evaluated preoperatively with noninvasive methods alone.

BACKGROUND

Congenital heart disease patients with single ventricle physiology undergo routine echocardiography and cardiac catheterization prior to superior cavopulmonary anastomosis to determine anatomic and hemodynamic suitability for this procedure.

METHODS

We performed a retrospective review of all infants (n = 114) evaluated for potential superior cavopulmonary anastomosis at our institution from January 1997 to June 2000.

RESULTS

Patients' median age was 5.5 months. Full echocardiograms were obtained in 79 patients (69%). At catheterization a total of 41 interventions were performed in 35 patients (31%). Twenty-seven patients (24%) were transfused, 18 patients (17%) required cardiac intensive care unit admission, and median length of stay following catheterization was 1 day (range 0 to 22). Complications occurred in 28 patients (25%), most transient. Of 51 patients who had complete echocardiograms without indication for catheterization, none subsequently had significant interventions and only 2 had new findings at catheterization. Three candidates were excluded from operation; all 111 others underwent successful procedures and survived to hospital discharge.

CONCLUSIONS

Interventions were frequent at catheterization prior to superior cavopulmonary anastomosis, but transient complications, transfusion, intensive care unit admission, and prolonged hospital length of stay were common. For patients in whom no issues indicating need for catheterization are identified by echocardiogram, routine catheterization rarely results in new information or intervention. These patients may be more safely evaluated preoperatively using exclusively noninvasive techniques.

Pediatric heart transplantation

Heart transplantation is now a treatment option with good outcome for infants and children with end-stage heart failure or complex, inoperable congenital cardiac defects. One-year and 5-year actuarial survival rates are high, approximately 75% and 65%, respectively, with overall patient survival half-life greater than 10 years. To date, survival has been improving as a result of reducing early mortality. Further reductions in late mortality, in part because of graft coronary artery disease and rejection, will allow achievement of the goal of decades-long survival. Quality of life in surviving children, as judged by activity, is usually "normal." Somatic growth is usually at the low normal range but linear growth can be reduced. Of infant recipients, 85% evaluated at 6 years of age or older were in an age-appropriate grade level. Long-term management of childhood heart recipients requires the collaboration of transplant physicians, given the increasing number of immunosuppressive agents and the balance between rejection and infection. Currently, recipients are maintained on immunosuppressive medications that target calcineurin (eg, cyclosporine, tacrolimus), lymphocyte proliferation (eg, azathioprine, mycophenolate mofetil [MMF], sirolimus) and, in some instances antiinflammatory corticosteroids. Emerging evidence now suggests a favorable immunologic opportunity for transplantation in childhood and, conversely, a higher mortality rate in children who have had prior cardiac surgery. Further studies are needed to define age-dependent factors that are likely to play a role in graft survival and possible graft-specific tolerance (eg, optimal conditions for tolerance induction and how immunosuppressive regimens should be changed with maturation of the immune system). As late outcomes continue to improve, the need for donor organs likely will increase, as transplantation affords a better quality and duration of life for children with complex congenital heart disease, otherwise facing a future of multiple palliative operations and chronic heart failure.

Diagnosis and management of pediatric myocarditis

Myocarditis is an insidious inflammatory disorder of the myocardium. As a clinical entity, it has been recognized for two centuries, but it defies traditional diagnostic tests. A greater understanding of the immune response underlying the pathobiology of the disorder can lead to a more rational therapeutic approach. The presentation, course and therapeutic options appear to be different in the pediatric compared with the adult population. An understanding of the difference between fulminant and acute progressive myocarditis has led to successful treatment strategies. A variety of new therapies are available, including antiviral agents, immunosuppression, and modulation of the biological response to inflammation. The specific question for patients with myocarditis is whether regimens designed to reduce or eliminate inflammation can provide clinical benefits compared with conventional heart failure therapy. This review highlights pathological mechanisms, modalities of diagnosis, and novel therapies which may improve outcomes.

Surgical emergencies during pediatric interventional catheterization

OBJECTIVE

To determine the incidence of catheter-related surgical emergencies during pediatric interventional catheterization procedures.

STUDY DESIGN

We reviewed all interventional catheter procedures (n = 578) over a 4-year period (April 1996 to April 2000) to determine any complication during interventional catheterization that required surgery within 24 hours after catheterization.

RESULTS

The overall incidence of surgical emergencies was 1.9% (70% confidence limits, 1.5% to 2.7%). Complications that required surgical intervention occurred with balloon dilation (valvuloplasty, angioplasty, n = 4), device deployment (coils, stents, atrial-septal defect devices, n = 5), transhepatic access (n = 1), and atrial transseptal puncture (n = 1). For the majority of interventions, the incidence of surgical emergencies was <4% except for two procedures (conduit and pulmonary artery angioplasty) with limited numbers of patients. There were no surgical emergencies during endomyocardial biopsy, coarctation angioplasty, or balloon atrial septostomy.

CONCLUSIONS

Surgery was required in 1.9% of all interventional catheter procedures. Surgical emergencies occurred during a wide variety of catheter interventions and could not be predicted by the type of procedure performed.

A practical approach for the diagnosis and management of dilated cardiomyopathy

Dilated cardiomyopathy (DCM) refers to a group of conditions of diverse etiology in which both ventricles are enlarged with reduced contractility. Certain correctable conditions associated with ventricular dysfunction can masquerade as DCM. Most of them can be identified with relatively inexpensive and readily available tests. A typical diagnostic work-up for a child with DCM also includes a number of investigations to identify the underlying cause, some of which are expensive and sophisticated. The average center in the developing world often does not have the facilities to carry out these investigations. The results of many of these investigations typically do not translate into a specific management strategy that makes a difference to prognosis. A significant number of children with DCM will eventually develop end-stage heart failure that requires cardiac transplantation with or without bridging procedures. This is an unrealistic option for the developing world. The management strategy of childhood DCM in the developing world needs to be tailored to the resources available with in a manner such that the overall prognosis is not substantially affected.

Anything but a biopsy: noninvasive monitoring for cardiac allograft rejection

Endomyocardial biopsy has stood the test of time as a surveillance technique; however, the expense, resources required, invasive nature, and low but definite risks have motivated investigators to pursue less invasive techniques. The search for noninvasive surveillance techniques for cardiac rejection have centered on measurements of cardiac function, intragraft electrical events, peripheral proteomic markers of graft micronecrosis, immune activation, and nonimmune accompaniments of rejection. Although several investigations allude to a reasonable negative predictive value of such monitoring, the specificity of these techniques remains poor. Until well-constructed studies not only define the predictive values of noninvasive techniques but also appropriately evaluate the clinical safety of any such approach, invasive endomyocardial biopsy will remain the gold standard.

Serum vascular endothelial growth factor as a surveillance marker for cellular rejection in pediatric cardiac transplantation

BACKGROUND

Early detection and treatment of acute rejection in cardiac transplant recipients significantly improves long-term survival. Endomyocardial biopsy is used routinely for diagnosing allograft rejection; however, in young children, this procedure carries some risk. We evaluated serum vascular endothelial growth factor (VEGF) as a potential surveillance marker of acute cellular rejection.

METHODS

Blood samples (n=62) were analyzed from 23 patients and compared with controls (n=18) using an ELISA for VEGF. Results were correlated with endomyocardial biopsy rejection grades.

RESULTS

Mean baseline VEGF levels of the transplant population were consistently higher than controls. Serum VEGF levels were significantly higher during acute cellular rejection when compared with the non-rejecting transplant group (700.7+/-154 pg/ml vs. 190.5+/-29 pg/ml). VEGF decreased two- to eightfold after immunosuppressive therapy in 9 of 11 rejection episodes.

CONCLUSIONS

These data suggest that VEGF may play a role in the pathogenesis of acute allograft rejection and it may serve as a reliable serologic surveillance marker.

Clinical, electrocardiographic, and histologic correlations in children with dilated cardiomyopathy

OBJECTIVE

To determine whether presenting electrocardiography is related to histologic findings and clinical outcomes in children with dilated cardiomyopathy.

BACKGROUND

Lymphocytic myocarditis is an important cause of childhood dilated cardiomyopathy, the outcome of which is unclear. The results of non-invasive investigations are often used to infer the presence or absence of lymphocytic myocarditis.

METHODS

Thirty-four children, presenting acutely with dilated cardiomyopathy, underwent both early electrocardiography and endomyocardial biopsy. The parameters examined included heart rate, PR, QRS, and corrected QT intervals, R-wave voltages in Leads V(1) and V(6), S-wave voltages in Leads V(1) and V(6), and sum of SV(1) and RV(6). We expressed measurements as Z scores, based on published normal values for age and gender.

RESULTS

A total of 15 patients had lymphocytic myocarditis on endomyocardial biopsy (Group I), and 19 had non-specific histologic findings (Group II). We did not distinguish the 2 groups by age, time to endomyocardial biopsy, or duration of follow-up. Group I patients had significantly smaller R-wave Z scores in Leads V(1) and V(6), and combined S in V(1) and R in V(6) Z scores (p < 0.02 for each). The positive and negative predictive values of an R-wave amplitude in V(6) < 5th percentile were 75% and 65%, respectively, for the diagnosis of lymphocytic myocarditis. An R-wave amplitude in V(6) > 95th percentile had a positive and negative predictive value of 80% and 63%, respectively, for the diagnosis of idiopathic dilated cardiomyopathy. Survival and freedom from late cardiac dysfunction were more common among Group I patients compared with Group II (p <or= 0.02 for both).

CONCLUSION

Myocardial histology cannot reliably be inferred from the presenting electrocardiogram. Survival and outcome for children with lymphocytic myocarditis is better than for those with non-specific histology.

Myocarditis in infants and children: A review for the paediatrician

Clinical myocarditis is uncommon in infants and children. The most common pathogen is Coxsackievirus B. The offending agent triggers an immune response, which results in myocardial edema with subsequent impairment of systolic and diastolic function. Newborns and infants are more severely affected because the immature myocardium has limited ways of adapting to an acute insult. Children typically present with sinus tachycardia and gallop on auscultation, cardiomegaly on chest x-ray and small voltages on electrocardiogram. The echocardiogram shows reduced ventricular function. Viral studies can isolate the pathogen. Myocardial biopsy is useful diagnostically, but carries a significant risk for the sick infant. The first line of treatment includes measures such as rest, oxygen and diuretics. Inotropic agents are useful in moderate to severe heart failure. The role of immunosuppressive therapy is not yet clearly established in the paediatric age group. Prognosis is guarded in newborns but more favourable in older children.

Acute myocarditis

Myocarditis is defined as inflammation of the myocardium accompanied by myocellular necrosis. Acute myocarditis must be considered in patients who present with recent onset of cardiac failure or arrhythmia. Often there is a history of an antecedent flu-like illness. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness. Giant cell myocarditis is a rare, frequently fatal disorder of unknown origin characterized by presence of giant cell inflammatory infiltrate in the myocardium. In recent years we have made good progress in understanding the causes, pathogenesis, natural history, diagnosis, and treatment of myocarditis. However, our knowledge is still far from complete. New information that extends our understanding of myocarditis is being reported constantly. This review summarizes recent advances in myocarditis, with an emphasis on the literature during the last year.

Endomyocardial biopsy in pediatric heart transplant recipients: a useful exercise? (Analysis of 1,169 biopsies)

The objective of this study was to define the diagnostic yield for endomyocardial biopsy (EMB) procedures performed for various indications in a large pediatric heart transplant population. Endomyocardial biopsy procedure has been employed as the 'gold standard' for rejection surveillance. Previous studies have questioned the value of surveillance EMB beyond the early post-transplant period. We retrospectively reviewed data on 82 pediatric heart transplant recipients with serial EMB. A total of 1,169 EMB were performed during a follow-up period of 2-149 months (median 41 months). EMB were classified by age at transplantation, time from transplant, immunosuppressive regimen used [tacrolimus vs. cyclosporin A (CsA)] and indication, i.e. surveillance, follow-up after rejection or lowering of immunosuppression, non-specific clinical symptoms and graft dysfunction. During the first year after heart transplantation, surveillance EMB demonstrated significant rejection [International Society for Heart and Lung Transplantation (ISHLT) grade > or = 3A] in 18% of biopsies with the yield being 14-43% for all other indications. Surveillance EMB 1-5 yr post-transplantation were found to have a lower diagnostic yield in infants (4%, vs. 13% in children) and in patients with favorable first-year rejection history (9% vs. 17% in 'frequent rejectors'). Tacrolimus-based immunosuppression was associated with significantly less rejection, but only in the first year post-transplantation (14% in tacrolimus vs. 24% in CsA surveillance EMB, p = 0.035). Surveillance EMB remains an important diagnostic tool for rejection surveillance during the first 5 years after pediatric heart transplantation. Endomyocardial biopsy is particularly warranted after reduction of immunosuppression and for monitoring for ongoing rejection after treatment of acute rejection episodes.