Beta-blocker therapy of severe congestive heart failure in infants with left to right shunts

Efficacy and safety of propranolol in infants with heart failure due to moderate-to-large ventricular septal defect (VSD-PHF study) - A prospective randomized trial

AIMS

The utility of beta-blocker therapy in infants with heart failure (HF) due to significant left-to-right shunt lesions is not known. The study aimed to assess the efficacy and safety of propranolol in infants with HF due to moderate-to-large ventricular septal defect (VSD).

METHODS

The prospective randomized trial included 80 infants with HF and moderate-to-large VSD, randomly allocated to receive either conventional therapy alone (n = 40) or propranolol plus conventional therapy (n = 40). The primary endpoint was a composite of all-cause mortality, hospitalization for HF and/or chest infection, and referral for surgery. The secondary clinical outcomes were the individual components of the composite endpoint. In addition, the patients were followed up to detect safety outcomes, for example, bronchospasm, bradyarrhythmia, and worsening HF symptoms.

RESULTS

The addition of propranolol therapy to the conventional medications did not result in significant improvement in the primary composite endpoint (32.50% vs. 52.50%; P = 0.07). There was a trend toward improvement, but the study is underpowered for this important question. However, propranolol therapy significantly decreased the risk of hospitalization (12.50% vs. 32.50%; P = 0.03) and worsening of Ross HF class (5.41% vs. 28.21%; P = 0.01) as compared to conventional therapy (estimated number needed to treat = 5). Propranolol did not result in any significant safety concerns in these infants except bronchospasm in an infant.

CONCLUSIONS

Propranolol therapy in infants with significant left-to-right shunt may prevent worsening in HF symptoms and hospitalization and is well tolerated. However, it does not reduce mortality or need for surgery.

Prorenin and active renin levels in paediatrics: a bioanalytical review

As part of the extended renin-angiotensin-aldosterone system, active renin and its precursor prorenin have been an area of research interest for decades. Although several studies showed a correlation with disease, other studies found no significant association, e.g. attributed to limited sample size or pharmacological effects of antihypertensive drugs. Since the measurement of both proteins has typically been carried out in adult populations, the data in paediatrics is limited. This review aimed to collate the current data on plasma renin and prorenin levels in children and compare the levels of healthy vs. the diseased state. A literature search using Medline resulted in 213 publications of which 15 studies were classified as relevant. In the extant studies in the literature, an age-dependent decline of renin plasma concentration was observed in newborns compared to adolescents. For children with cardiovascular disease, five studies were identified that provide limited insight into the pathophysiological regulation of renin. In general, sample handling is still a crucial step, which might particularly affect measured active renin concentrations due to conformational changes of its precursor prorenin. A reliable assessment for prorenin levels in the maturating population is yet not possible due to the low number of available publications. Three different approaches to quantify prorenin were found and raise the question on the comparability of these methods. The review emphazised several weaknesses and highlights the need for an accurate procedure to determine levels of active renin as well as prorenin in its closed and open form.

Beta-blockers for congestive heart failure in children

BACKGROUND

Beta-blockers are an essential part of standard therapy in adult congestive heart failure and therefore, are expected to be beneficial in children. However, congestive heart failure in children differs from that in adults in terms of characteristics, aetiology, and drug clearance. Therefore, paediatric needs must be specifically investigated. This is an update of a Cochrane review previously published in 2009.

OBJECTIVES

To assess the effect of beta-adrenoceptor-blockers (beta-blockers) in children with congestive heart failure.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and LILACS up to November 2015. Bibliographies of identified studies were checked. No language restrictions were applied.

SELECTION CRITERIA

Randomised, controlled, clinical trials investigating the effect of beta-blocker therapy on paediatric congestive heart failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and assessed data from the included trials.

MAIN RESULTS

We identified four new studies for the review update; the review now includes seven studies with 420 participants. Four small studies with 20 to 30 children each, and two larger studies of 80 children each, showed an improvement of congestive heart failure with beta-blocker therapy. A larger study with 161 participants showed no evidence of benefit over placebo in a composite measure of heart failure outcomes. The included studies showed no significant difference in mortality or heart transplantation rates between the beta-blocker and control groups. No significant adverse events were reported with beta-blockers, apart from one episode of complete heart block. A meta-analysis of left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) data showed a very small improvement with beta-blockers. However, there were vast differences in the age, age range, and health of the participants (aetiology and severity of heart failure; heterogeneity of diagnoses and co-morbidities); there was a range of treatments across studies (choice of beta-blocker, dosing, duration of treatment); and a lack of standardised methods and outcome measures. Therefore, the primary outcomes could not be pooled in meta-analyses.

AUTHORS' CONCLUSIONS

There is not enough evidence to support or discourage the use of beta-blockers in children with congestive heart failure, or to propose a paediatric dosing scheme. However, the sparse data available suggested that children with congestive heart failure might benefit from beta-blocker treatment. Further investigations in clearly defined populations with standardised methodology are required to establish guidelines for therapy. Pharmacokinetic investigations of beta-blockers in children are also required to provide effective dosing in future trials.

Beta-blockers for congestive heart failure in children

BACKGROUND

Beta-blockers are an essential part of standard therapy in adult congestive heart failure and therefore, are expected to be beneficial in children. However, congestive heart failure in children differs from that in adults in terms of characteristics, aetiology, and drug clearance. Therefore, paediatric needs must be specifically investigated. This is an update of a Cochrane review previously published in 2009.

OBJECTIVES

To assess the effect of beta-adrenoceptor-blockers (beta-blockers) in children with congestive heart failure.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and LILACS up to November 2015. Bibliographies of identified studies were checked. No language restrictions were applied.

SELECTION CRITERIA

Randomised, controlled, clinical trials investigating the effect of beta-blocker therapy on paediatric congestive heart failure.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and assessed data from the included trials.

MAIN RESULTS

We identified four new studies for the review update; the review now includes seven studies with 420 participants. Four small studies with 20 to 30 children each, and two larger studies of 80 children each, showed an improvement of congestive heart failure with beta-blocker therapy. A larger study with 161 participants showed no evidence of benefit over placebo in a composite measure of heart failure outcomes. The included studies showed no significant difference in mortality or heart transplantation rates between the beta-blocker and control groups. No significant adverse events were reported with beta-blockers, apart from one episode of complete heart block. A meta-analysis of left ventricular ejection fraction (LVEF) and fractional shortening (LVFS) data showed a very small improvement with beta-blockers.However, there were vast differences in the age, age range, and health of the participants (aetiology and severity of heart failure; heterogeneity of diagnoses and co-morbidities); there was a range of treatments across studies (choice of beta-blocker, dosing, duration of treatment); and a lack of standardised methods and outcome measures. Therefore, the primary outcomes could not be pooled in meta-analyses.

AUTHORS' CONCLUSIONS

There is not enough evidence to support or discourage the use of beta-blockers in children with congestive heart failure, or to propose a paediatric dosing scheme. However, the sparse data available suggested that children with congestive heart failure might benefit from beta-blocker treatment. Further investigations in clearly defined populations with standardised methodology are required to establish guidelines for therapy. Pharmacokinetic investigations of beta-blockers in children are also required to provide effective dosing in future trials.

Biomarkers in congenital heart disease: do natriuretic peptides hold the key?

Congenital heart disease is the most common congenital abnormality. The long-term prognosis of these patients has changed significantly over the last half century, thanks to improvements in cardiovascular diagnosis, surgery and postoperative care. However, residual lesions are not uncommon and many of the interventions performed remain palliative rather than reparative, leading to the development of ventricular dysfunction and heart failure. Natriuretic peptides are well-established markers of disease severity and prognosis in patients with heart failure due to noncongenital (acquired) heart disease. However, the role of biomarkers in congenital heart disease is unclear. This review highlights the impact of neurohormonal activation in patients with congenital heart disease, as well as the usefulness of assessing natriuretic peptide levels in specific clinical situations.

Role of β-blocker therapy in pediatric heart failure

Heart failure is becoming an increasingly common and significant problem in the field of pediatric cardiology. The numerous types of cardiomyopathies, and more recently, long-term survival of patients with congenital heart disease, have added to a growing patient population. Over the last several decades, our knowledge base regarding mechanisms of disease and therapeutic intervention in adult patients with heart failure has drastically changed. The most recent and important breakthrough in the pharmacologic treatment of heart failure has been the particular role of β-blocker therapy. This medication has led to significant improvements in survival and symptoms in adults, with less convincing findings in limited studies in pediatrics. The ability to study the benefits of this therapy in patients has been challenging owing to the heterogeneity of the patient population and lack of large sample sizes. However, as we investigate the mechanisms behind the disease process, the differences that exist between disease conditions and ages, and the significant alterations that may exist at the molecular and genetic level, our understanding of β-blocker therapy in pediatric heart failure will improve, and ultimately may lead to patient-specific therapy.

Beta-blockers for congestive heart failure in children

BACKGROUND

Beta-blockers are an essential part of standard therapy in adult congestive heart failure and are therefore also expected to be beneficial in children. However, congestive heart failure in children differs strongly from that in adults in terms of characteristics and aetiology; also, an increased drug clearance has been reported. Paediatric needs have therefore to be specifically investigated.

OBJECTIVES

To assess the effect of beta-adrenoceptor-blockers in children with congestive heart failure.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library (Issue 4 2007), MEDLINE (1966 to January 2008), EMBASE (1980 to January 2008), and LILACS (1980 to January 2008). Bibliographies of identified studies were checked. No language restrictions were applied.

SELECTION CRITERIA

Randomised, controlled clinical trials investigating the effect of beta-blocker therapy on paediatric congestive heart failure.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted and assessed data from the included trials.

MAIN RESULTS

Three studies with an overall number of 203 participants were identified. Two small studies, with 20 and 22 children respectively, showed an improvement of congestive heart failure, while a larger study with 161 participants showed no evidence of benefit over placebo in the composite measure of heart failure outcomes which was the main outcome measure of the trial (56% improvement in both the placebo and the treatment group, p=0.74). However, study populations showed vast differences with regard to treatment (choice of beta-blocker, dosing, duration of treatment), age and age range of the participants and in particular with regard to condition (aetiology and severity of heart failure; homogeneity of condition in the study population). In addition methods and outcome measures differed strongly and were not standardised. The results can therefore not be compared against each other.

AUTHORS' CONCLUSIONS

There are not enough data to recommend or discourage the use of beta-blockers in children with congestive heart failure. Further investigations in clearly defined populations with standardised methodology are required to establish guidelines for therapy. Pharmacokinetic investigations of beta-blockers in children are required to provide effective dosing in future trials.

Pediatric heart failure therapy with beta-adrenoceptor antagonists

Management of chronic heart failure in pediatrics has been altered by the adult literature showing improvements in mortality and hospitalization rates with the use of beta-adrenoceptor antagonists (beta-blockers) for routine therapy of all classes of ischemic and non-ischemic heart failure. Many pediatric heart failure specialists have incorporated these agents into their routine management of pediatric heart failure related to dilated cardiomyopathy or ventricular dysfunction in association with congenital heart disease. Retrospective and small prospective case series have shown encouraging improvements in cardiac function and symptoms, but interpretation has been complicated by the high rate of spontaneous recovery in pediatric patients. A recently completed pediatric double-blind, randomized, placebo-controlled clinical trial showed no difference between placebo and two doses of carvedilol over a 6-month period of follow-up, with significant improvement of all three groups over the course of evaluation. Experience with adults has suggested that only certain beta-blockers, including carvedilol, bisoprolol, nebivolol, and metoprolol succinate, should be used in the treatment of heart failure and that patients with high-grade heart failure may derive the most benefit. Other studies surmise that early or prophylactic use of these medications may alter the risk of disease progression in some high-risk subsets, such as patients receiving anthracyclines or those with muscular dystrophy. This article reviews these topics using experience as well as data from all the recent pediatric studies on the use of beta-blockers to treat congestive heart failure, especially when related to systolic ventricular dysfunction.

Closure of symptomatic ventricular septal defects: how early is too early?

With improvements in technology and surgical technique, pediatric cardiologists are challenging surgeons to close symptomatic ventricular septal defects (VSDs) in ever smaller patients. Although delaying surgery may facilitate operative repair, early intervention decreases the period of time these patients require therapy to prevent heart failure, maintains growth, and minimizes exposure to increased pulmonary pressures. To evaluate early intervention, we compare the outcomes of VSD closure in different-sized children. From December 2002 to July 2005, 225 patients underwent closure of a VSD. These patients were divided into four weight-based groups: <4 kg (group 1, n = 28), 4 to 6 kg (group 2, n = 93), 6 to 10 kg (group 3, n = 47), and >10 kg (group 4, n = 57). We reviewed operative and postoperative data, and comparisons were made between the groups. Median weights and ages at the time of surgery were 3.5 kg and 77 days (group 1), 4.9 kg and 128 days (group 2), 7.1 kg and 309 days (group 3), and 18.2 kg and 190 days (group 4). Operative data included cardiopulmonary bypass (CPB), aortic cross-clamp, and procedure times. CPB (p = 0.064), cross-clamp (p = 0.665), and procedure (p = 0.187) times were not significantly affected by decreasing weight. Postoperative continuous data included duration of ventilation and length of intensive care unit (ICU) and hospital stay. Ventilation (p = 0.667) and ICU (p = 0.976) times and length of hospital stay (p = 0.905) were also unaffected by decreasing weight. Postoperative catagoric data included complications and presence of a residual VSD. There was no significant difference in complications (p = 0.763) or residual VSD (p = 0.696) between groups. There was no mortality and no persistent heart block requiring placement of a permanent pacemaker. With improvements in technology and surgical technique, safe and effective VSD closure can be performed in increasingly smaller children. Earlier repair decreases the period of time these patients require aggressive medical therapy to prevent heart failure and maintain growth. It also decreases the period of time for which they are exposed to increased pulmonary pressures and are at risk for infectious respiratory complications. It does not appear to affect operative or postoperative outcomes.

What is the optimal time to repair atrioventricular septal defect and common atrioventricular valvar orifice?

OBJECTIVE

With improvements in technology and surgical technique, paediatric cardiologists are challenging surgeons to repair balanced atrioventricular septal defects in smaller patients. Early repair minimizes aggressive medical therapy to prevent heart failure, maintains growth, and limits exposure to elevated pulmonary pressures. We compare the outcomes of repair among different-sized children.

METHODS

From December 2002 to July 2005, 92 patients underwent repair of an atrioventricular septal defect with common atrioventricular valvar orifice and balanced ventricles. We reviewed operative and postoperative data. We excluded patients weighing more than 10 kilograms, but included those who underwent concomitant closure of a patent oval foramen or atrial septal defect, or ligation of a patent arterial duct. Those requiring other concomitant procedures were excluded from the analysis.

RESULTS

The median weight at repair was 4.9 kilograms, with a range from 2.93 to 7.9 kilograms, and the median age was 5.1 months, with a range from 0.39 to 9.6 months. Operative data included the time required for cardiopulmonary bypass, aortic cross-clamping, and the overall procedure. These times were not significantly affected by decreasing weight. Postoperative continuous data included duration of ventilation and length of intensive care unit and hospital stay. Stay in intensive care (p = 0.006) and hospital (p = 0.007) both increased significantly with decreasing weight. Postoperative categorical data included presence of residual ventricular septal defects, regurgitation across the left atrioventricular valve, and complications. While there was no difference in residual defects (p = 0.166) or valvar regurgitation (p = 0.729), there was a significantly higher presence of complications with decreasing weight (p = 0.0043). There was no mortality, and no persistent heart block requiring placement of a permanent pacemaker.

CONCLUSIONS

Our data shows that, with the exception of a slightly longer and more complicated postoperative course, early surgery for symptomatic patients with atrioventricular septal defects and common atrioventricular valvar orifice can be undertaken safely and effectively in smaller children with excellent outcomes.

Exercise Intolerance in Adults with Congenital Heart Disease

This article describes the ways to assess exercise capacity in adults with congenital heart disease (ACHD) and the impact of exercise intolerance in the population. It also discusses the likely pathogenesis of exercise intolerance in ACHD, the similarities between ACHD and acquired heart failure, and potential therapeutic options.

Prospective single-arm protocol of carvedilol in children with ventricular dysfunction

The objective of this study was to evaluate the safety and efficacy of carvedilol in pediatric patients with stable moderate heart failure. We performed a single-arm prospective drug trial at three academic medical centers and the results were compared to historical controls. Patients were 3 months to 17 years old with an ejection fraction <40% in the systemic ventricle for at least 3 months on maximal medical therapy including ACE inhibitors. Treated patients were started on 0.1 mg/kg/day and uptitrated to 0.8 mg/kg/day or the maximal tolerated dose. Echocardiographic parameters of function were prospectively measured at entry and at 6 months. Two composite endpoints were recorded: severe decline in status and significant clinical change. Adverse events were reviewed by a safety committee. Data were also collected from untreated controls with dilated cardiomyopathy meeting entry criteria, assessed over a similar time frame. Twenty patients [12 dilated cardiomyopathy (DCM) and 8 congenital] with a median age of 8.4 years (range, 8 months to 17.8 years) were treated with carvedilol. Three patients discontinued the drug during the study. At entry, there was no statistical difference in age, weight, or ejection fraction between the treated group and controls. The ejection fraction of the treated DCM group improved significantly from entry to 6 months (median, 31 to 40%, p = 0.04), with no significant change in ejection fraction in the control group [median, 29 to 27%, p = not significant (NS)]. The median increase in ejection fraction was larger for the treated DCM group than for the untreated DCM controls (7 vs 0%, p = 0.05). By Kaplan-Meier analysis, time to death or transplant tended to be longer in treated patients (p = 0.07). The difference in the proportion of patients with severe decline in status or significant clinical change in the treated group was not significant compared to the controls (5 vs 12%, p = NS). We conclude that in this prospective protocol of pediatric patients, the use of adjunct carvedilol in the DCM group improved ejection fraction compared to untreated controls and trended toward delaying time to transplant or death.

Applying standard therapies to new targets: the use of ACE inhibitors and B-blockers for heart failure in adults with congenital heart disease

Increasingly, patients and clinicians are being confronted with congestive heart failure (CHF) as a late complication of congenital heart disease. However, medical management of heart failure in this patient group represents a challenge because of complex hemodynamics and a lack of evidence from large randomized controlled trials to guide therapy. This article will review the evidence of the use angiotensin converting enzyme inhibitors (ACEIs) and beta-blockers (BBs) in left heart failure, discuss the mechanisms of heart failure as they pertain to congenital heart disease and review the limited literature of the use of neurohormonal antagonists in congenital heart disease. Some recommendations for use of angiotensin converting enzyme inhibitors and beta-blockers in heart failure due various congenital heart lesions are offered. Well-designed clinical trials are urgently needed to extend the impressive reductions in morbidity and mortality achieved with neurohormonal blockade in left ventricular (LV) heart failure to adults with congenital heart disease.

Should beta-blockers be used for the treatment of pediatric patients with chronic heart failure?

In multiple clinical trials, beta-blockers have been shown to significantly improve morbidity and mortality in adults with chronic congestive heart failure, but there is little reported experience with their use in children. Heart failure involves activation of the adrenergic nervous system and other neurohumoral systems in order to maintain cardiovascular homeostasis. These compensatory mechanisms have been shown to cause myocardial damage with chronic activation, which has been hypothesized to be a major contributing factor to the clinical deterioration of adults with heart failure. Studies have demonstrated inhibition of this neurohumoral response and concomitant clinical benefits with beta-blockers. Consequently, beta-blockers have evolved to become an important part of comprehensive medical therapy for congestive heart failure in adults. Pediatric heart failure represents an entirely different spectrum of disease, caused more commonly by congenital heart disease than cardiomyopathy. Surgical palliation and correction are important components of pediatric heart failure therapy, and residual, postsurgical cardiac lesions can lead to chronic heart failure. Although neurohumoral activation in children is similar to that in adults with heart failure, there are important differences from adults in physiology and developmental changes that are especially observed in infants. Current published clinical experience with beta-blocker use in children with heart failure is limited to case series with relatively small numbers of patients. Nevertheless, these series show consistent symptomatic improvement, and improvement in ventricular systolic function in patients with cardiomyopathies and congenital heart disease, similar to findings in adults. Adverse effects were common and many patients in these studies had adverse outcomes (death and/or need for transplantation). One study has noted differences in pharmacokinetics in children compared with adults. However, a multicenter, randomized controlled trial to evaluate carvedilol in pediatric heart failure from systolic ventricular dysfunction is currently ongoing and should help to clarify the efficacy and tolerability of carvedilol in children.

Endogenous nitric oxide and soluble tumor necrosis factor receptor levels are enhanced in infants with congenital heart disease

OBJECTIVE

This study was designed to investigate cytokine and nitric oxide levels in pediatric patients suffering from chronic heart failure and to investigate effects of beta-blocker treatment on these levels.

PATIENTS

Fifteen infants with heart failure resulting from left-to-right shunts with pulmonary overcirculation were compared with 11 infants with cyanotic heart defects with reduced pulmonary blood flow. Four of these patients were finally treated with the beta-blocker propranolol.

MEASUREMENTS

Endogenous nitric oxide production was determined by measuring total plasma nitrite/nitrate (Griess method), and levels of soluble tumor necrosis factor receptors type 1 and type 2 (TNF-R1 and TNF-R2, respectively) were measured by commercially available enzyme-linked immunosorbent assay.

MAIN RESULTS

In infants with left-to-right shunts, soluble tumor necrosis factor receptor levels were significantly elevated as compared with infants with cyanosis (TNF-R1: 1.7 +/- 0.5 vs. 0.8 +/- 0.3 ng/mL; p =.0003; TNF-R2: 8.1 +/- 4.0 vs. 5.1 +/- 3.2 ng/mL; p =.049). In addition, we found a significant correlation between nitrate/nitrite levels and TNF-R1 (r =.70; p =.0001) or TNF-R2 (r =.62; p =.0013), respectively. Furthermore, the tumor necrosis factor receptor levels in four children after beta-blocker treatment were lower as compared with levels before beta-blocker treatment.

CONCLUSIONS

Immune mechanisms, such as cytokine or nitric oxide production, may be involved in pathogenesis of heart failure in children, and may contribute to the beneficial effects of beta-blocker treatment observed in these patients.

[Chronic heart failure in children: recent contributions of physiopathology and therapeutic implications]

The treatment of chronic heart failure has made remarkable progress over the past ten years. Recent advances in our understanding of the pathophysiologic mechanisms involved in heart failure syndrome have led to changes in our approach to the treatment of children. The goals of the therapy have shifted from purely hemodynamic manipulation to a combination of hemodynamic and neurohumoral modulation. As for adults, three therapeutic classes have recently emerged: conversion enzyme inhibitors, spironolactone and beta-blockers. Pediatricians know that a child is not a small adult and we have to think about heart failure on the basis of etiology, the age of the patient, and circulatory physiology and maturation.

Propranolol treatment of congestive heart failure in infants with congenital heart disease: The CHF-PRO-INFANT Trial. Congestive heart failure in infants treated with propanol

AIM

Infants with congenital heart disease and left-to-right shunts may develop significant clinical symptoms of congestive heart failure in spite of therapy with digoxin and diuretics. We investigated the effects of beta-blockade in infants with severe heart failure.

METHODS AND RESULTS

We performed a prospective, randomized, open monocenter trial in infants treated with digoxin and diuretics (n=10) in comparison to 10 infants receiving additional beta-blocker therapy. After 17 days on average beta-blocker treated infants (propranolol:1,6 mg/kg/day) improved significantly with respect to Ross heart failure score (3.3+/-2.3 vs. 8.3+/-1.9, P=0.002), lower renin levels (338+/-236 vs. 704+/-490 microU/l, P=0.008) and lower mean heart rates in Holter ECG (118+/-10 vs. 142+/-11 beats/min, P<0.001). While digoxin and diuretic treated infants had unchanged mean heart rate (149+/-8 vs. 148+/-10 beats/min), less decrease of symptoms (Ross Score: 8.5+/-1.7 vs. 6.8+/-2.3, P=0.02) but a significant increase of renin levels (139+/-102 vs. 938+/-607 microU/l, P=0.001).

CONCLUSION

Additional propranolol treatment but not digoxin and diuretics alone can effectively reduce clinical symptoms of heart failure in infants with congenital heart disease, who suffer from increased neurohormonal activation.

Activity of the renin–angiotensin–aldosterone and sympathetic nervous system and their relation to hemodynamic and clinical abnormalities in infants with left-to-right shunts

We studied neurohormonal, clinical and invasively measured hemodynamic data of 47 infants with left-to-right shunts and varying degrees of congestive failure. When referred to a clinical heart failure score, plasma renin activities (r=0.71) and norepinephrine levels (r=0.43) are significantly increased. Arterial hypotension seems to be the hemodynamic trigger of renin release (r=-0.72), but not decreased systemic cardiac index (r=-0.43), the magnitude of the left-to-right shunt (r=0.33) or a reduced ejection fraction (r=0.12). These data indicate neurohormonal activation in infants with left-to-right shunts with preserved myocardial function is similar to the activation in adults with heart failure secondary to myocardial pump failure. These findings have to be considered for optimal medical treatment of these infants with angiotensin-converting enzyme inhibitors or beta-blockers.

Carvedilol as therapy in pediatric heart failure: an initial multicenter experience

OBJECTIVE

The objective was to determine the dosing, efficacy, and side effects of the nonselective beta-blocker carvedilol for the management of heart failure in children.

STUDY DESIGN

Carvedilol use in addition to standard medical therapy for pediatric heart failure was reviewed at 6 centers.

RESULTS

Children with dilated cardiomyopathy (80%) and congenital heart disease (20%), age 3 months to 19 years (n = 46), were treated with carvedilol. The average initial dose was 0.08 mg/kg, uptitrated over a mean of 11.3 weeks to an average maintenance dose of 0.46 mg/kg. After 3 months on carvedilol, there were improvements in modified New York Heart Association class in 67% of patients (P =.0005, chi2 analysis) and improvement in mean shortening fraction from 16.2% to 19.0% (P =.005, paired t test). Side effects, mainly dizziness, hypotension, and headache, occurred in 54% of patients but were well tolerated. Adverse outcomes (death, cardiac transplantation, and ventricular-assist device placement) occurred in 30% of patients.

CONCLUSIONS

Carvedilol as an adjunct to standard therapy for pediatric heart failure improves symptoms and left ventricular function. Side effects are common but well tolerated. Further prospective study is required to determine the effect of carvedilol on survival and to clearly define its role in pediatric heart failure therapy.

Pharmacologic considerations in the neonate with congenital heart disease

Advances in knowledge about the developing cardiovascular system and compensatory physiologic changes that occur in infants with congenital heart disease have led to new approaches in the management of cardiac failure and arrhythmias. Information about the pharmacologic effects, pharmacokinetics, and pharmacodynamics of newer agents used in the management of congenital heart disease have led to more appropriate use of these medications to prolong survival and improve outcomes.

Medical management of chronic heart failure in children

Chronic heart failure (CHF) in children occurs mostly as a result of systolic dysfunction of the systemic ventricle or of congenital defects leading to large left-to-right shunts and pulmonary overcirculation. The ensuing symptoms and signs are similar in both cases, and include respiratory distress, poor feeding and growth, and hepatic congestion. Grading the severity of the symptoms accurately and reproducibly is important for studying CHF and the response to therapy. The Ross classification for young children and the New York Heart Association classification for older children are frequently utilized for such grading. The standard therapy for CHF in children consists of diuretics, to reduce cardiac preload and improve symptoms, and the maximization of nutritional support. The role of digoxin in treating CHF in children is controversial, especially regarding those children with pulmonary overcirculation where the function of the systemic ventricle is usually well preserved. As the importance of neurohormonal changes in the pathogenesis of worsening CHF is elucidated, newer medications aimed at counteracting such changes are becoming more important in the medical therapy of CHF in children. ACE inhibitors improve function and survival in adults with CHF, and they probably do the same in children with systemic ventricular dysfunction. It is less clear how effective they are in pulmonary overcirculation, but patients with high flow and low pulmonary resistance are most likely to benefit. In infants receiving treatment with ACE inhibitors, it is necessary to monitor for renal insufficiency or renal failure. beta-Adrenoceptor blockade has also been established as an effective therapy for adults with CHF with beneficial effects on survival and left ventricular function. While data for the pediatric population are limited, early studies suggest that beta-adrenoceptor antagonists (beta-blockers) may work well in infants and children with CHF. Caution must be used by starting treatment with very low dosages of beta-blockers and gradually increasing to the desired goals with close monitoring of blood pressure and heart rate. It is clear that larger multicenter trials are crucial to our ability to provide the most appropriate treatment for children with CHF. The demand for effective medical treatment will increase as more patients with palliated single ventricles survive surgery and then develop CHF from dysfunction of a hypertrophic and dilated single ventricle.

Digitalis use in children: an uncertain future

The therapeutic indications for digoxin in the treatment of children with large left-to-right shunts continue to be reassessed. New insights into the alterations in cardiac function imposed by this hemodynamic burden have shown preserved systolic performance. Pharmacological interventions that improve cardiac output by afterload reduction or other modalities have proven useful and potentially have low risk for serious toxicity. Early and successful surgical treatment of most conditions causing pulmonary overcirculation has shortened the duration of medical management and prevented many of the untoward complications of this pathology. As new agents are forthcoming to treat various cardiac conditions, use-by-tradition of cardiac glycosides has appropriately diminished. While the understanding of complicated molecular aspects of cation transport have been enhanced by the unique actions of cardiac glycosides, their clinical utility has decreased. This report summarizes studies on the use of cardiac glycosides in the treatment of large left-to-right shunts in children.

Beta-adrenergic blockers in the treatment of pediatric heart failure

Beta-adrenergic blocking agents for the treatment of chronic congestive heart failure in adults have gained wide acceptance. Although the exact mechanism of their effect is still not entirely clear, the preponderance of data support the hypothesis that the primary mechanism of action of beta-blocking agents in chronic heart failure is to prevent and reverse adrenergically-mediated intrinsic myocardial dysfunction and remodeling. Large, multicenter trials in adults with chronic congestive heart failure have definitively shown that beta-blockers improve left ventricular ejection fraction, symptoms, and survival when compared to placebo. Although experience with beta-blockers in children is limited, anecdotal evidence suggests that children with chronic congestive heart failure may also benefit from this therapy. Large trials in children are currently in the planning stages in order to attempt to determine the indications, dosages, and optimal use of beta-blockers in children with chronic congestive heart failure.

Effectiveness of low dose captopril versus propranolol therapy in infants with severe congestive failure due to left-to-right shunts

To evaluate the therapeutical effects of the angiotensin converting enzyme inhibitor Captopril to the beta-blocker Propranolol in infants with congestive failure due to pulmonary overcirculation, we retrospectively analysed clinical, neurohormonal and hemodynamic data in 22 infants, 11 of whom were treated with Captopril (Group 1), 11 with Propranolol (Group 2). Age, weight, number of palliative operations, plasma renin activities and pulmonary to systemic flow ratios (3.5 vs. 3.5) were not significantly different prior to Captopril or Propranolol therapy. If treatment with digoxin and diuretics did not succeed, the infants were additionally treated with Captopril (1 mg/kg) for a mean of 7.4 months, or with 1.9 mg/kg Propranolol for 9.2 months.

RESULTS

1 mg/kg Captopril did not effectively suppress angiotensin converting enzyme in the steady state at trough level (92+/-52 vs. 87+/-50 nmol/min/ml). In the Propranolol group, the clinical heart failure score (2.6+/-1.5 vs. 7. 4+/-2.5) and plasma renin activities (14+/-10 vs. 101+/-70 ng/ml/h) were significantly lower, compared to the Captopril group. Length of hospital stay (23+/-9 vs. 52+/-24 days) was lower and weight gain (126+/-38 vs. 86+/-84 g/week) was higher within 3 months after starting Propranolol therapy. Significantly lower left atrial pressures (6.2+/-2.2 vs. 13.4+/-9.2 mmHg) and lower endiastolic ventricular pressures (7.6+/-2.5 vs. 12.6+/-4.0 mmHg) during pre-operative cardiac catheterization indicated a better diastolic ventricular function under chronic Propranolol treatment.

CONCLUSION

Although high dose Captopril was not evaluated in this study, when compared to patients on low Captopril dosages, infants who received Propranolol treatment showed improvement in heart failure scores, shorter lengths of hospital stay, lower plasma renin activities and better diastolic ventricular functions.

Overview of the management of pediatric heart failure

For the most part of this the century heart failure syndrome was understood as a pump failure disorder with hemodynamic consequences stemming from the same myocardial dysfunction. In addition supply and demand theories were used to explain the nature of symptoms. As a result, therapeutic strategies were directed at correcting the abnormal hemodynamic conditions and normalizing the delivery of the much needed nutrients. Improvement of cardiac pump function with inotropic drugs and abnormal circulatory conditions with afterload and preload modifications became therapeutic goals and standards of care. However, while vasodilators and inotropic drugs immediately improved symptoms, hemodynamics and functional status, in the long term they either did not affect or worsen the natural history of heart failure. In pediatrics, this is further complicated by the lack of large scale trials addressing issues pertinent to the particularities that affect heart failure in children. In the late 1980s and 1990s heart failure has evolved into a more complex, multiple and interactive pathophysiologic disorder. Today not only the abnormal hemodynamics but also the biological disorders are pharmacologic targets. The reversal or slowing of myocardial maladaptation has become one of the most important therapeutic goals. With this end in mind therapeutic strategies may seem counterintuitive and paradoxical, such as the use of beta-blockers. This review will address the current thinking and therapeutic modalities used today in the treatment of heart failure syndrome in the adult population. We also discuss some of the issues why we think that these principles can be extrapolated to the pediatric population.