Myocardial Response to Milrinone in Single Right Ventricle Heart Disease

Medical Therapies for Heart Failure in Hypoplastic Left Heart Syndrome

Significant surgical and medical advances over the past several decades have resulted in a growing number of infants and children surviving with hypoplastic left heart syndrome (HLHS) and other congenital heart defects associated with a single systemic right ventricle (RV). However, cardiac dysfunction and ultimately heart failure (HF) remain the most common cause of death and indication for transplantation in this population. Moreover, while early recognition and treatment of single ventricle-related complications are essential to improving outcomes, there are no proven therapeutic strategies for single systemic RV HF in the pediatric population. Importantly, prototypical adult HF therapies have been relatively ineffective in mitigating the need for cardiac transplantation in HLHS, likely due to several unique attributes of the failing HLHS myocardium. Here, we discuss the most commonly used medical therapies for the treatment of HF symptoms in HLHS and other single systemic RV patients. Additionally, we provide an overview of potential novel therapies for systemic ventricular failure in the HLHS and related populations based on fundamental science, pre-clinical, clinical, and observational studies in the current literature.

Management of circulatory failure after Fontan surgery

With improvement in survival after Fontan surgery resulting in an increasing number of older survivors, there are more patients with a Fontan circulation experiencing circulatory failure each year. Fontan circulatory failure may have a number of underlying etiologies. Once Fontan failure manifests, prognosis is poor, with patient freedom from death or transplant at 10 years of only about 40%. Medical treatments used include traditional heart failure medications such as renin-angiotensin-aldosterone system blockers and beta-blockers, diuretics for symptomatic management, antiarrhythmics for rhythm control, and phosphodiesterase-5 inhibitors to decrease PVR and improve preload. These oral medical therapies are typically not very effective and have little data demonstrating benefit; if there are no surgical or catheter-based interventions to improve the Fontan circulation, patients with severe symptoms often require inotropic medications or mechanical circulatory support. Mechanical circulatory support benefits patients with ventricular dysfunction but may not be as useful in patients with other forms of Fontan failure. Transplant remains the definitive treatment for circulatory failure after Fontan, but patients with a Fontan circulation face many challenges both before and after transplant. There remains significant room and urgent need for improvement in the management and outcomes of patients with circulatory failure after Fontan surgery.

Effect of Loading Changes on the Intraventricular Pressure Measured by Color M-Mode Echocardiography in Rats

Evaluation of diastolic function is a pivotal challenge due to limitations of the conventional echocardiography, especially when the heart rate is rapid as in rats. Currently, by using color M-mode echocardiography (CMME), intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG) in early diastole can be generated and are available as echocardiographic indices. These indices are expected to be useful for the early diagnosis of heart failure (HF), especially diastolic dysfunction. There have not been any studies demonstrating changes in IVPD and IVPG in response to changes in loading conditions in rats. Therefore, the present study aims to evaluate CMME-derived IVPD and IVPG changes in rats under various loading conditions. Twenty rats were included, divided into two groups for two different experiments, and underwent jugular vein catheterization under inhalational anesthetics. Conventional echocardiography, CMME, and 2D speckle tracking echocardiography were measured at the baseline (BL), after intravenous infusion of milrinone (MIL, n = 10), and after the infusion of hydroxyethyl starch (HES, n = 10). Left ventricular IVPD and IVPG were calculated from color M-mode images and categorized into total, basal, mid-to-apical, mid, and apical parts, and the percentage of the corresponding part was calculated. In comparison to the BL, the ejection fraction, mid-to-apical IVPG, mid IVPG, and apical IVPD were significantly increased after MIL administration (p < 0.05); meanwhile, the end-diastolic volume, E-wave velocity, total IVPD, and basal IVPD were significantly increased with the administration of HES (p < 0.05). The increase in mid-to-apical IVPD, mid IVPD, and apical IVPD indicated increased relaxation. A significant increase in basal IVPD reflected volume overloading by HES. CMME-derived IVPD and IVPG are useful tools for the evaluation of various loading conditions in rats. The approach used in this study provides a model for continuous data acquisition in chronic cardiac disease models without drug testing.

Cardiovascular Drug Therapy during Interstage After Hybrid Approach: A Single-Center Experience in 51 Newborns with Hypoplastic Left Heart

BACKGROUND

Newborns with hypoplastic left heart (HLH) are usually palliated with the Norwood procedure or a hybrid stage I procedure. Hybrid is our preferred approach. Given the critical relationship between stage I, interstage, and comprehensive stage II or advanced biventricular repair, we hypothesized that appropriate drug treatment is a significant therapeutic cornerstone, especially for the management of the high-risk interstage.

METHODS

We report a single-center observational study addressing the cardiovascular effects of, in particular, oral β-blockers and the additional use of angiotensin-converting enzyme (ACE) and mineralocorticoid inhibitors.

RESULTS

In total, 51 newborns-30 with HLH syndrome (HLHS) and 21 with HLH complex (HLHC)-with a median bodyweight of 3.0 kg (range 1.9-4.4; nine with bodyweight ≤ 2500 g) underwent an uneventful "Giessen hybrid approach" using a newly approved duct stent. All patients were discharged home with a single, double or triple therapy consisting of ß-blockers, ACE and mineralocorticoid inhibitors; 90% of the patients received bisoprolol, 10% received propranolol, 72% received lisinopril, and 78% received spironolactone. Resting heart rate decreased from 138 bpm (range 112-172; n = 51) at admission to 123 bpm (range 99-139; n = 51) at discharge and 110 bpm before stage II/biventricular repair/heart transplantation (range 90-140; n = 37) accompanied by favorable bodyweight gain. No side effects were evident.

CONCLUSION

In view of drug risk/benefit profiles, as well as the variable morphology and hemodynamics, the highly selective β1-adrenoceptor blocker bisoprolol is our preferred drug for treatment of HLHS/HLHC in the interstage. We avoid using ACE inhibitor monotherapy and exclude potential risks for coronary and cerebral perfusion pressure beforehand.

Heart failure in single right ventricle congenital heart disease: physiological and molecular considerations

Because of remarkable surgical and medical advances over the past several decades, there are growing numbers of infants and children living with single ventricle congenital heart disease (SV), where there is only one functional cardiac pumping chamber. Nevertheless, cardiac dysfunction (and ultimately heart failure) is a common complication in the SV population, and pharmacological heart failure therapies have largely been ineffective in mitigating the need for heart transplantation. Given that there are several inherent risk factors for ventricular dysfunction in the setting of SV in addition to probable differences in molecular adaptations to heart failure between children and adults, it is perhaps not surprising that extrapolated adult heart failure medications have had limited benefit in children with SV heart failure. Further investigations into the molecular mechanisms involved in pediatric SV heart failure may assist with risk stratification as well as development of targeted, efficacious therapies specific to this patient population. In this review, we present a brief overview of SV anatomy and physiology, with a focus on patients with a single morphological right ventricle requiring staged surgical palliation. Additionally, we discuss outcomes in the current era, risk factors associated with the progression to heart failure, present state of knowledge regarding molecular alterations in end-stage SV heart failure, and current therapeutic interventions. Potential avenues for improving SV outcomes, including identification of biomarkers of heart failure progression, implications of personalized medicine and stem cell-derived therapies, and applications of novel models of SV disease, are proposed as future directions.

Regenerative therapies in young hearts with structural or congenital heart disease

Pediatric heart failure (HF) is rare. The prognosis is generally poor. HF is most frequently related to cardiomyopathy or congenital heart disease (CHD). Associated phenotypes are HF with preserved (HFpEF) or reduced ejection fraction (HFrEF); both in children with biventricular or univentricular circulation. Cardiac growth, differentiation, proliferation and consecutively regenerative and repair mechanisms are inversely related to the patient's age; edaphic and circulating cardiac progenitor cells as well; in sum, there are enormous endogenous potentials repairing a diseased heart in particular in young children. Efforts supporting pediatric cardiac regeneration are clearly justified; cell-based therapies have been addressed in small series of children with end-stage HF of either the left or right ventricle, more recently in randomized clinical trials. Different cell populations like autologous bone marrow mononuclear cells, progenitor cells or cardiac derived cells have been injected into coronaries or directly into the myocardium. Beneficial at least transient improvement of cardiac function was observed in patients with dilative cardiomyopathy and CHD, mainly hypoplastic left heart syndrome (HLHS). Cellular repopulation and possibly more crucial, paracrine effects contributed in slowing down progression of pediatric end-stage HF. Our review summarizes the current knowledge in different scenarios of HF by cell-based cardiac therapies in critically ill children. Based on the actual clinical experience future work to distinguish responders from non-responders among other refinements will lead to individualized precision treatment of HF in children, what means a lot to a child on a long list waiting for heart transplantation (HTX).

A comprehensive review on the potential therapeutic benefits of phosphodiesterase inhibitors on cardiovascular diseases

Phosphodiesterases are a group of enzymes that hydrolyze cyclic nucleotides, which assume a key role in directing intracellular levels of the second messengers' cAMP and cGMP, and consequently cell function. The disclosure of 11 isoenzyme families and our expanded knowledge of their functions at the cell and molecular level stimulate the improvement of isoenzyme selective inhibitors for the treatment of various diseases, particularly cardiovascular diseases. Hence, future and new mechanistic investigations and carefully designed clinical trials could help reap additional benefits of natural/synthetic PDE inhibitors for cardiovascular disease in patients. This review has concentrated on the potential therapeutic benefits of phosphodiesterase inhibitors on cardiovascular diseases.

Heart Failure in Pediatric Patients With Congenital Heart Disease

Heart failure (HF) is a complex clinical syndrome resulting from diverse primary and secondary causes and shared pathways of disease progression, correlating with substantial mortality, morbidity, and cost. HF in children is most commonly attributable to coexistent congenital heart disease, with different risks depending on the specific type of malformation. Current management and therapy for HF in children are extrapolated from treatment approaches in adults. This review discusses the causes, epidemiology, and manifestations of HF in children with congenital heart disease and presents the clinical, genetic, and molecular characteristics that are similar or distinct from adult HF. The objective of this review is to provide a framework for understanding rapidly increasing genetic and molecular information in the challenging context of detailed phenotyping. We review clinical and translational research studies of HF in congenital heart disease including at the genome, transcriptome, and epigenetic levels. Unresolved issues and directions for future study are presented.

Can Cyclic Nucleotide Phosphodiesterase Inhibitors Be Drugs for Parkinson's Disease?

Parkinson's disease (PD) has no known cure; available therapies are only capable of offering temporary, symptomatic relief to the patients. Varied therapeutic strategies that are clinically used for PD are pharmacological therapies including dopamine replacement therapies (with or without adjuvant), postsynaptic dopamine receptor stimulation, dopamine catabolism inhibitors and also anticholinergics. Surgical therapies like deep brain stimulation and ablative surgical techniques are also employed. Phosphodiesterases (PDEs) are enzymes that degrade the phosphodiester bond in the second messenger molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). A number of PDE families are highly expressed in the striatum including PDE1-4, PDE7, PDE9 and PDE10. There are growing evidences to suggest that these enzymes play a critical role in modulating cAMP-mediated dopamine signalling at the postsynaptic region. Therefore, it is clear that PDEs, given the broad range of subtypes and their varied tissue- and region-specific distributions, will be able to provide a range of possibilities as drug targets. There is no phosphodiesterase inhibitor currently approved for use against PD. The development of small molecule inhibitors against cyclic nucleotide PDE is a particularly hot area of investigation, and a lot of research and development is geared in this direction with major players in the pharmaceutical industry investing heavily in developing such potential drug entities. This review, while critically assessing the existing body of literature on brain PDEs with particular interest in the striatum in the context of motor function regulation, indicates it is certainly likely that PDE inhibitors could be developed as therapeutic agents against PD.

Cardiac Adenylyl Cyclase and Phosphodiesterase Expression Profiles Vary by Age, Disease, and Chronic Phosphodiesterase Inhibitor Treatment

BACKGROUND

Pediatric heart failure (HF) patients have a suboptimal response to traditional HF medications, although phosphodiesterase-3 inhibition (PDE3i) has been used with greater success than in the adult HF population. We hypothesized that molecular alterations specific to children with HF and HF etiology may affect response to treatment.

METHODS AND RESULTS

Adenylyl cyclase (AC) and phosphodiesterase (PDE) isoforms were quantified by means of quantitative real-time polymerase chain reaction in explanted myocardium from adults with dilated cardiomyopathy (DCM), children with DCM, and children with single-ventricle congenital heart disease of right ventricular morphology (SRV). AC and PDE expression profiles were uniquely regulated in each subject group and demonstratde distinct changes in response to chronic PDE3i. There was unique up-regulation of AC5 in adult DCM with PDE3i (fold change 2.415; P = .043), AC2 in pediatric DCM (fold change 2.396; P = .0067), and PDE1C in pediatric SRV (fold change 1.836; P = .032). Remarkably, PDE5A expression was consistently increased across all age and disease groups.

CONCLUSIONS

Unique regulation of AC and PDE isoforms supports a differential molecular adaptation to HF in children compared with adults, and may help identify mechanisms specific to the pathogenesis of pediatric HF. Greater understanding of these differences will help optimize medical therapies based on age and disease process.