Enalapril for severe heart failure in infancy

Enalapril and Enalaprilat Pharmacokinetics in Children with Heart Failure Due to Dilated Cardiomyopathy and Congestive Heart Failure after Administration of an Orodispersible Enalapril Minitablet (LENA-Studies)

Angiotensin-converting enzyme inhibitors (ACEI), such as enalapril, are a cornerstone of treatment for pediatric heart failure which is still used off-label. Using a novel age-appropriate formulation of enalapril orodispersible minitablets (ODMTs), phase II/III open-label, multicenter pharmacokinetic (PK) bridging studies were performed in pediatric patients with heart failure due to dilated cardiomyopathy (DCM) and congenital heart disease (CHD) in five participating European countries. Children were treated for 8 weeks with ODMTs according to an age-appropriate dosing schedule. The primary objective was to describe PK parameters (area under the curve (AUC), maximal concentration (Cmax), time to reach maximal concentration (t-max)) of enalapril and its active metabolite enalaprilat. Of 102 patients, 89 patients (n = 26, DCM; n = 63 CHD) were included in the primary PK endpoint analysis. Rate and extent of enalapril and its active metabolite enalaprilat were described and etiology and age could be identified as potential PK modifying factors. The dosing schedule appeared to be tolerated well and did not result in any significant drug-related serious adverse events. The PK analysis and the lack of severe safety events supports the applied age-appropriate dosing schedule for the enalapril ODMTs.

Exercising with a Single Ventricle: Limitations and Therapies

Treatment for Hypoplastic Left Heart Syndrome (HLHS) and other single ventricle conditions requires a series of surgical interventions for long-term survival, typically culminating in the Fontan procedure. The result is an abnormal circulatory physiology with an absence of a sub-pulmonary ventricle. Exercise capacity in the Fontan circulation is often limited and is due to multiple factors, both central and peripheral. Multiple interventions, both pharmacologic and nonpharmacologic, have been studied to attempt to overcome these inherent limitations. This review will focus on the physiology of the exercising Fontan patient and on the interventions aimed at the enhancement of exercise capacity studied thus far.

Drug Treatment of Heart Failure in Children: Gaps and Opportunities

Medical therapy for pediatric heart failure is based on a detailed mechanistic understanding of the underlying causes, which are diverse and unlike those encountered in most adult patients. Diuresis and improved perfusion are the immediate goals of care in the child with acute decompensated heart failure. Conversion to maintenance oral therapy for heart failure is based on the results of landmark studies in adults, as well as recent pediatric clinical trials and heart failure guidelines. There will continue to be an important role for newer drugs, some of which are in active trials in adults, and some of which are already approved for use in children. The need to plan for clinical trials in children during drug development for heart failure is emphasized.

Safety, Feasibility, and Impact of Enalapril on Cardiorespiratory Physiology and Health in Preterm Infants with Systemic Hypertension and Left Ventricular Diastolic Dysfunction

Neonatal hypertension has been increasingly recognized in premature infants with bronchopulmonary dysplasia (BPD); of note, a sub-population of these infants may have impaired left ventricular (LV) diastolic function, warranting timely treatment to minimize long term repercussions. In this case series, enalapril, an angiotensin-converting enzyme (ACE) inhibitor, was started in neonates with systemic hypertension and echocardiography signs of LV diastolic dysfunction. A total of 11 patients were included with birth weight of 785 ± 239 grams and gestational age of 25.3 (24, 26.1) weeks. Blood pressure improvement was noticed within 2 weeks of treatment. Improvement in LV diastolic function indices were observed with a reduction in Isovolumic Relaxation Time (IVRT) from 63.1 ± 7.2 to 50.9 ± 7.4 msec and improvement in the left atrium size indexed to aorta (LA:Ao) from1.73 (1.43, 1.88) to 1.23 (1.07, 1.29). Neonatal systemic hypertension is often underappreciated in ex-preterm infants and may be associated with important maladaptive cardiac changes with long term implications. It is biologically plausible that identifying and treating LV diastolic dysfunction in neonates with systemic hypertension may have a positive modulator effect on cardiovascular health in childhood and beyond.

Pharmacology of enalapril in children: a review

Enalapril is an angiotensin-converting enzyme (ACE) inhibitor that is used for the treatment of (paediatric) hypertension, heart failure and chronic kidney diseases. Because its disposition, efficacy and safety differs across the paediatric continuum, data from adults cannot be automatically extrapolated to children. This review highlights paediatric enalapril pharmacokinetic data and demonstrates that these are inadequate to support with certainty an age-related effect on enalapril/enalaprilat pharmacokinetics. In addition, our review shows that evidence to support effective and safe prescribing of enalapril in children is limited, especially in young children and heart failure patients; studies in these groups are either absent or show conflicting results. We provide explanations for observed differences between age groups and indications, and describe areas for future research.

Safety of Enalapril in Infants Admitted to the Neonatal Intensive Care Unit

Enalapril is used to treat hypertension and congestive heart failure in infants. However, enalapril is not labeled for neonates, and safety data in infants are sparse. To evaluate the safety of enalapril in young infants, we conducted a retrospective cohort study of infants who were exposed to enalapril in the first 120 days of life and were cared for in 348 neonatal intensive care units from 1997 to 2012. We determined the proportion of exposed infants who developed adverse events, including death, hypotension requiring pressors, hyperkalemia, and elevated serum creatinine. Using multivariable logistic regression, we examined risk factors for adverse events, including postnatal age at first exposure, exposure duration, gestational age group, small for gestational age status, race, sex, 5-min Apgar score, and inborn status. Of a cohort of 887,910 infants, 662 infants (0.07%) were exposed to enalapril. Among exposed infants, 142 infants (21%) suffered an adverse event. The most common adverse event was hyperkalemia (13%), followed by elevated serum creatinine (5%), hypotension (4%), and death (0.5%). Significant risk factors for adverse events included postnatal age <30 days at first exposure and longer exposure duration. This study is the largest to date examining the safety of enalapril in young term and preterm infants without significant structural cardiac disease.

Heart Failure in Children

Heart failure (HF) in children differs from that in adults in many respects. The causes and clinical presentations may differ considerably among children of different age groups and between children and adults. The time of onset of HF holds the key to the etiological diagnosis. Clinical presentation of HF in younger children can be nonspecific requiring heightened degree of suspicion. The overall outcome with HF is better in children than in adults as HF in children is commonly due to structural heart disease and reversible conditions which are amenable to therapy. The principles of management include treatment of the cause, correction of any precipitating event, and treatment of systemic or pulmonary congestion. Though HF in adults has been the subject of extensive research and generation of evidence-based guidelines, there is a scarcity of evidence base in pediatric HF.

Effect of preoperative angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker use on hemodynamic variables in pediatric patients undergoing cardiopulmonary bypass

BACKGROUND

Some have suggested that children undergoing cardiac surgery who receive angiotensin-converting enzyme (ACE) inhibitors experience a greater degree of hypotension after anesthesia induction and in the immediate postcardiopulmonary bypass period than children who did not receive these drugs. Therefore, we examined the effect of ACE inhibitor/angiotensin II receptor blocker (ARB) therapy on intraoperative hemodynamics and vasopressor use in pediatric patients undergoing cardiac surgery.

METHODS

In a retrospective cohort study of patients younger than 18 years who underwent cardiopulmonary bypass between March 1, 2010, and April 1, 2011, we compared intraoperative hemodynamics and vasopressor use between patients who received preoperative ACE inhibitor/ARB therapy and those who did not. The primary outcome was vasoactive infusion score after cardiopulmonary bypass.

RESULTS

The occurrence of hypotension did not differ significantly between the ACE inhibitor/ARB group and the control group during induction of anesthesia or at any time point after cardiopulmonary bypass. At 0, 30, 60, and 90 minutes after cessation of cardiopulmonary bypass, patients on ACE inhibitor/ARB therapy tended to have a higher vasoactive infusion score (7.1, 7.6, 9.4, and 11.3) than patients in the control group (6.3, 6.1, 6.0, and 6.7). Although this difference became more pronounced over time, it did not reach statistical significance.

CONCLUSION

The use of preoperative ACE inhibitors and ARBs in pediatric patients undergoing cardiac surgery did not significantly increase the incidence of hypotension after induction of anesthesia and did not increase significantly the vasoconstrictor requirements upon weaning from cardiopulmonary bypass; however, additional prospective studies are needed.

Renin-angiotensin-aldosterone genotype influences ventricular remodeling in infants with single ventricle

BACKGROUND

We investigated the effect of polymorphisms in the renin-angiotensin-aldosterone system (RAAS) genes on ventricular remodeling, growth, renal function, and response to enalapril in infants with single ventricle.

METHODS AND RESULTS

Single ventricle infants enrolled in a randomized trial of enalapril were genotyped for polymorphisms in 5 genes: angiotensinogen, angiotensin-converting enzyme, angiotensin II type 1 receptor, aldosterone synthase, and chymase. Alleles associated with renin-angiotensin-aldosterone system upregulation were classified as risk alleles. Ventricular mass, volume, somatic growth, renal function using estimated glomerular filtration rate, and response to enalapril were compared between patients with ≥2 homozygous risk genotypes (high risk), and those with <2 homozygous risk genotypes (low risk) at 2 time points: before the superior cavopulmonary connection (pre-SCPC) and at age 14 months. Of 230 trial subjects, 154 were genotyped: Thirty-eight were high risk, and 116 were low risk. Ventricular mass and volume were elevated in both groups pre-SCPC. Ventricular mass and volume decreased and estimated glomerular filtration rate increased after SCPC in the low-risk (P<0.05), but not the high-risk group. These responses were independent of enalapril treatment. Weight and height z-scores were lower at baseline, and height remained lower in the high-risk group at 14 months, especially in those receiving enalapril (P<0.05).

CONCLUSIONS

Renin-angiotensin-aldosterone system-upregulation genotypes were associated with failure of reverse remodeling after SCPC surgery, less improvement in renal function, and impaired somatic growth, the latter especially in patients receiving enalapril. Renin-angiotensin-aldosterone system genotype may identify a high-risk subgroup of single ventricle patients who fail to fully benefit from volume-unloading surgery. Follow-up is warranted to assess long-term impact.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT00113087.

Enalapril in infants with single ventricle: results of a multicenter randomized trial

BACKGROUND

Angiotensin-converting enzyme inhibitor therapy improves clinical outcome and ventricular function in adults with heart failure. Infants with single-ventricle physiology have poor growth and are at risk for abnormalities in ventricular systolic and diastolic function. The ability of angiotensin-converting enzyme inhibitor therapy to preserve ventricular function and improve somatic growth and outcomes in these infants is unknown.

METHODS AND RESULTS

The Pediatric Heart Network conducted a double-blind trial involving 230 infants with single-ventricle physiology randomized to receive enalapril (target dose 0.4 mg . kg(-1) . d(-1)) or placebo who were followed up until 14 months of age. The primary end point was weight-for-age z score at 14 months. The primary analysis was intention to treat. A total of 185 infants completed the study. There were 24 and 21 withdrawals or deaths in the enalapril and placebo groups, respectively (P=0.74). Weight-for-age z score was not different between the enalapril and placebo groups (mean+/-SE -0.62+/-0.13 versus -0.42+/-0.13, P=0.28). There were no significant group differences in height-for-age z score, Ross heart failure class, brain natriuretic peptide concentration, Bayley scores of infant development, or ventricular ejection fraction. The incidence of death or transplantation was 13% and did not differ between groups. Serious adverse events occurred in 88 patients in the enalapril group and 87 in the placebo group.

CONCLUSIONS

Administration of enalapril to infants with single-ventricle physiology in the first year of life did not improve somatic growth, ventricular function, or heart failure severity. The results of this randomized trial do not support the routine use of enalapril in this population.

Rationale and design of a trial of angiotensin-converting enzyme inhibition in infants with single ventricle

BACKGROUND

Angiotensin converting enzyme (ACE) inhibitors are known to improve clinical outcome and ventricular function in adults with heart failure. Infants with single-ventricle physiology show abnormalities in ventricular function as well as poor growth. The ability of an ACE inhibitor to preserve ventricular function and improve growth in these infants is unknown.

METHODS

The Pediatric Heart Network designed a randomized, double-blind trial to compare outcomes in infants with single-ventricle physiology receiving enalapril or placebo. Neonates < or =45 days old were eligible. The primary outcome is weight-for-age Z-score at 14 months of age. Secondary outcomes include other measures of somatic growth, laboratory and functional measures of heart failure, developmental indices, measures of ventricular size and function, and the relationship of the renin-angiotensin-aldosterone system genotype to the response to enalapril. The incidence and spectrum of adverse events will also be compared between treatment groups.

RESULTS

A total of 1,245 neonates were screened and 533 (43%) were eligible. The consent rate was 43%; 230 subjects were enrolled. Parental reluctance to participate was the primary reason for non-consent in 79% of the eligible nonconsenting patients. Randomized patients were older, more likely to be male, and more likely to have hypoplastic left heart syndrome than the eligible patients who did not enroll.

CONCLUSIONS

The results of this randomized trial will make an important contribution to the management of infants with single-ventricle physiology by determining whether initiation of ACE inhibition therapy in the neonatal period improves growth, clinical outcome, and ventricular function.

ACE inhibitors in pediatric patients with heart failure

This article reviews reports of ACE inhibitor use in pediatric heart failure and summarizes the present implications for clinical practice. Captopril, enalapril, and cilazapril are orally active ACE inhibitors, and widely used in pediatric cardiology, although more than ten other ACE inhibitors have been applied clinically in adults. Effects of ACE inhibitors on the renin-angiotensin-aldosterone system in pediatric patients are similar to those in adults. ACE inhibitors lower aortic pressure and systemic vascular resistance, do not affect pulmonary vascular resistance significantly, and lower left atrial and right atrial pressures in pediatric patients with heart failure. In infants with a large ventricular septal defect and pulmonary hypertension, ACE inhibitors decrease left-to-right shunt in those infants with elevated systemic vascular resistance. ACE inhibitors induce a small increase in left ventricular ejection fraction, left ventricular fractional shortening, and systemic blood flow in children with left ventricular dysfunction, mitral regurgitation, and aortic regurgitation. These beneficial effects usually persist long term without the development of tolerance. Therapeutic trials of ACE inhibitors have been reported in children with heart failure and divergent hemodynamics, including myocardial dysfunction, left-to-right shunt, such as large ventricular septal defect and pulmonary hypertension, aortic or mitral regurgitation, and Fontan circulation. Hypotension and renal failure usually occur within 5 days after starting ACE inhibition or increasing the dose and, in most cases, recovery is seen after reduction or cessation of the drug. With all ACE inhibitors, smaller doses are administered initially to prevent excessive hypotension, and doses are increased gradually to the target dose. Captopril is administered orally, usually every 8 hours. Daily doses range from 0.3 to 1.5 mg/kg in children. Enalapril is administered orally, once or twice a day, and daily doses range from 0.1 to 0.5 mg/kg. Enalaprilat is administered intravenously, one to three times a day, in doses ranging from 0.01 to 0.05 mg/kg/dose. For the treatment of chronic heart failure in children, ACE inhibitors are essential along with other medications including diuretics, digoxin, and beta-blockers (beta-adrenoceptor antagonists).

Enalapril-induced acute renal failure in a newborn infant

A full-term baby boy developed congestive cardiac failure secondary to left-to-right shunts. He developed acute renal failure following the administration of oral enalapril given for the treatment of cardiac failure. There was no underlying renal disease or renal artery stenosis. He required three peritoneal dialyses, following which he recovered from the renal failure.

Randomised controlled trial comparing an acute paediatric hospital at home scheme with conventional hospital care

AIMS

To assess the clinical effectiveness of a paediatric hospital at home service compared to conventional hospital care.

METHODS

A total of 399 children suffering from breathing difficulty (n = 202), diarrhoea and vomiting (n = 125), or fever (n = 72) were randomised to Hospital at Home or in-patient paediatric care. Main outcome measures were: comparative clinical effectiveness as measured by readmission rate within three months (used as a proxy for parental coping with illness); and length of stay/care and comparative satisfaction of both patients and carers.

RESULTS

Clinical effectiveness of both services was not significantly different. Length of care was one day longer in the Hospital at Home group; however, most parents and children preferred home care.

CONCLUSIONS

Hospital at Home is a clinically acceptable form of care for these groups of acute paediatric illness. Readmission rates within three months failed to show any advantage in terms of parental coping. Parents and patients expressed a strong preference for hospital at home.

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.

Angiotensin-converting enzyme inhibitor therapy for ventricular dysfunction in infants, children and adolescents: a review

Angiotensin-converting enzyme (ACE) inhibitors have become an important part of the pharmacologic armamentarium in the battle against treatment of ventricular dysfunction. There have been a number of large controlled, randomized trials in adults with both asymptomatic and symptomatic ventricular dysfunction, which confirm the safety and efficacy of this category of drugs for the treatment of this potentially lethal condition. ACE inhibitors may be used to treat infants, children and adolescents with asymptomatic and symptomatic ventricular dysfunction as well. The data supporting their use in children is less complete than that concerning the treatment of adults. We review here the various causes of ventricular dysfunction and congestive heart failure (CHF) in infants, children, and adolescents; the data available regarding treatment of these conditions with ACE inhibitors, and the safety and efficacy of these drugs for the various conditions. The pharmacokinetics and proposed mechanisms of action of ACE inhibitors in children are reviewed, as are speculated long-term results of ACE inhibitor use in cohorts of growing children. Recommendations are made for future studies.

New drugs in the treatment of heart failure

New therapeutic strategies as well as the development of drugs with more specific targets have been fueled by disappointments in the treatment of adult heart failure. Calcium sensitizers, vesnarinone and angiotensin channel blockers will be addressed in this manuscript. The physiologic and pharmacologic principles that justify their use in the management of heart failure are reviewed. Calcium sensitizers increase myocardial contractility and in part they bypass the adenylyl cyclase cascade, which gives them a more favorable energy profile. Vesnarinone is a quinolinone derivative with ion channel modulation properties, which result in a positive inotropic effect and prolongation of the action potential. In addition vesnarinone has immunomodulatory properties. Angiotensin-converting enzyme inhibitors are the cornerstones for the treatment of heart failure. The discovery of some putative drawbacks to ACE inhibition has challenged this supremacy. Angiotensin receptor blockers have been developed hoping to overcome these deficiencies. Myocardial developmental differences highlight the shortcomings of attempting to extrapolate data on drugs and cellular physiology in adults to children. Studies are needed addressing standards of care, quality of life, morbidity and mortality, neurohumoral activation, its modulation and the consequences of these therapies in pediatric heart failure.

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.

Enalapril does not enhance exercise capacity in patients after Fontan procedure

BACKGROUND

Angiotensin-converting enzyme inhibitors improve exercise capacity in adults with congestive heart failure by decreasing systemic vascular resistance and improving ventricular diastolic function. Patients who have undergone the Fontan procedure have decreased cardiac output, increased systemic vascular resistance, abnormal diastolic function, and decreased exercise capacity compared with normal people.

METHODS AND RESULTS

To test the hypothesis that afterload reduction therapy alters hemodynamic variables and augments exercise capacity in patients after a Fontan procedure, we compared the results of graded exercise with maximal effort from 18 subjects (14.5+/-6.2 years of age, 4 to 19 years after Fontan procedure) in a randomized, double-blind, placebo-controlled crossover trial using enalapril (0.2 to 0.3 mg x kg[-1] x d[-1], maximum 15 mg). Each treatment was administered for 10 weeks. Diastolic filling patterns at rest were assessed by Doppler determination of the systemic atrioventricular valve flow velocity at the conclusion of each therapy. No difference was detected in resting heart rate, blood pressure, or cardiac index. Diastolic filling patterns were also similar. Exercise duration was not different (6.4+/-2.6 [enalapril] versus 6.7+/-2.6 minutes [placebo]). The mean percent increase in cardiac index from rest to maximum exercise was slightly but significantly decreased in subjects after 10 weeks of enalapril therapy (102+/-34% [enalapril] versus 125+/-34% [placebo]; P<.02). At maximal exercise, cardiac index (3.5+/-0.9 [enalapril] versus 3.8+/-0.9 L x min[-1] x m2 [placebo]), oxygen consumption (18.3+/-9 [enalapril] versus 20.5+/-7 mL x min[-1] x kg[-1] [placebo]), minute ventilation (57.5+/-17 [enalapril] versus 55.4+/-19 L/min [placebo]), and total work (247+/-181 [enalapril] versus 261+/-197 W [placebo]) were not different.

CONCLUSIONS

We conclude that enalapril administration for 10 weeks does not alter abnormal systemic vascular resistance, resting cardiac index, diastolic function, or exercise capacity in patients who have undergone a Fontan procedure.

Acute renal failure with ACE inhibition in aortic coarctation

A 43 year old man with inoperable aortic coarctation and severe hypertension requiring near maximal anti-hypertensive treatment was admitted in severe heart failure. After 2 weeks of treatment the heart failure and blood pressure were incompletely controlled and angiotensin converting enzyme (ACE) inhibitor was started. Serum creatinine was normal before starting the ACE inhibitor and on discharge from hospital. The patient was re-admitted a week later with gross fluid retention and in renal failure. In the absence of alternative causes, a diagnosis of ACE inhibitor-induced renal failure was made and treatment was stopped. The patient required haemodialysis for 2 days and within 1 week the renal function had reverted to normal and has remained so for 1 year. We propose that the renal haemodynamics in severe aortic coarctation are similar to those in bilateral severe renal artery stenosis and advise caution in the use of ACE inhibitors for adults with aortic coarctation.

Efficacy and dosage of enalapril in congenital and acquired heart disease

In a tertiary referral centre 63 patients underwent 67 treatment periods with enalapril. The median age was 5.4 months. All children had signs of heart failure: congestive cardiac failure with breathlessness at rest was present in 88%. Haemodynamic groups were left-to-right shunt (n = 15), impaired ventricular function (n = 14), after cardiac surgery (n = 23), valvar regurgitation (n = 12), and hypertension (n = 3). Serial clinical, radiological, and laboratory data were used to judge outcome. The mean (SD) maximal dose was 0.30 (0.21) mg/kg/day. Thirty nine (58%) patients improved, 20 (30%) showed no improvement, and eight (12%) had side effects requiring discontinuation of enalapril. Renal failure in eight patients was related to young age, low weight, and left-to-right shunt group. Three patients died in congestive heart failure with renal failure. Enalapril was clinically safe and effective for children with cardiac failure secondary to ventricular impairment, valvar regurgitation, or after cardiac surgery. Renal failure was a problem in young infants with left-to-right shunts.

Inhibition of angiotensin converting enzyme with enalapril maleate in infants with congestive heart failure

We studied the inhibition of angiotensin converting enzyme (ACE) in eight infants with congestive heart failure (CHF) poorly controlled with digoxin and diuretics, treated orally with 0.25 mg kg-1 enalapril maleate once a day. Baseline ACE activities were compared between these infants and control children without CHF or ACE inhibitor. Except for one infant who vomited, inhibition of ACE activity was 75.5 +/- 12.2%, 75.5 +/- 10.5% and 51.7 +/- 12.2%, at 4, 12 and 24 h after drug intake respectively. There was no correlation between postnatal age and inhibition of ACE activity. In infants with CHF, mean baseline ACE activity was significantly higher than in control infants (36.4 +/- 7.2 mu ml-1 vs 26.9 +/- 6.9 mu ml-1, P < 0.05). These results were very similar to those seen in adults.

Acute hemodynamic effects of converting enzyme inhibition in children with intracardiac shunts

The short-term hemodynamic effects of intravenous enalaprilat were assessed in 26 infants and children, aged 6 months to 15 years, with intracardiac shunts undergoing cardiac catheterization. Pulmonary and systemic pressure, flow, and resistance indices were measured by the direct Fick method before and 30 min after enalaprilat at 0.06 mg/kg. Aortic and pulmonary artery pressure decreased 15 and 20%, respectively, by 10 min, with little further change at 30 min. The heart rate did not change significantly and there was no reduction in systemic flow. In those with a large ventricular septal defect and normal or near-normal pulmonary resistance (less than 3.5 u.m2, n = 8), the mean pulmonary-systemic flow ratio decreased from 2.9 +/- 0.3 to 2.4 +/- 0.3 (p less than 0.05) and the mean left-to-right shunt from 7.4 +/- 0.8 to 5.9 +/- 0.7 L/min/m2 (p less than 0.02). Those with an elevated pulmonary vascular resistance (greater than 5 u.m2, n = 8) showed a varied response. Two children, both with Down's syndrome, an atrioventricular canal defect, and reversible pulmonary hypertension (as assessed by an infusion of isoproterenol), had no decrease in pulmonary vascular resistance with enalaprilat. There were no adverse effects. Converting enzyme inhibitors may benefit "heart failure" associated with large ventricular septal defects and normal or mildly elevated pulmonary resistance.