Current Cardiology Reviews (v.12, #2)

Meet Our Editorial Board Member by Carl (CHIP) Lavie (83-83).

Clinical Characteristics and Treatment of Cardiomyopathies in Children by Jack F. Price, Aamir Jeewa, Susan W. Denfield (85-98).
Cardiomyopathies are diseases of the heart muscle, a term introduced in 1957 to identify a group of myocardial diseases not attributable to coronary artery disease. The definition has since been modified to refer to structural and or functional abnormalities of the myocardium where other known causes of myocardial dysfunction, such as systemic hypertension, valvular disease and ischemic heart disease, have been excluded. In this review, we discuss the pathophysiology, clinical assessment and therapeutic strategies for hypertrophic, dilated and hypertrophic cardiomyopathies, with a particular focus on aspects unique to children.

The Pathophysiology of Heart Failure in Children: The Basics by Jarrod D. Knudson, Antonio G. Cabrera (99-103).
Few data exist on the pathophysiologic changes in pediatric heart failure. Most of the knowledge has evolved from animal models of ischemic or idiopathic dilated cardiomyopathy. This review addresses the pathophysiologic changes that occur in the failing heart from animal models and the adult experience to unique aspects of heart failure in children.

Cardiopulmonary interactions are present but inconsequential in humans with normal cardiac and respiratory function; however, in the presence of significant impairment in either system, the importance of the interplay between cardiovascular and pulmonary systems cannot be overstated. This review will discuss the physiologic underpinnings and consequences of these interactions in patients with heart failure.

The purpose of this review is to discuss the management of the low cardiac output syndrome (LCOS) following surgery for congenital heart disease. The LCOS is a well-recognized, frequent post-operative complication with an accepted collection of hemodynamic and physiologic aberrations. Approximately 25% of children experience a decrease in cardiac index of less than 2 L/min/m2 within 6-18 hours after cardiac surgery. Post-operative strategies that may be used to manage patients as risk for or in a state of low cardiac output include the use of hemodynamic monitoring, enabling a timely and accurate assessment of cardiovascular function and tissue oxygenation; optimization of ventricular loading conditions; the judicious use of inotropic agents; an appreciation of and the utilization of positive pressure ventilation for circulatory support; and, in some circumstances, mechanical circulatory support. All interventions and strategies should culminate in improving the relationship between oxygen supply and demand, ensuring adequate tissue oxygenation.

Hemodynamic Monitoring in the Acute Management of Pediatric Heart Failure by Rocky Tsang, Paul Checchia, Ronald A Bronicki (112-116).
One of the basic tenets of cardiac critical care is to ensure adequate tissue oxygenation. As with other critical illness such as trauma and acute myocardial infarction studies have demonstrated that making the right diagnosis at the right time improves outcomes. The same is true for the management of patients at risk for or in a state of shock. In order to optimize outcomes an accurate and timely assessment of cardiac function, cardiac output and tissue oxygenation must be made. This review discusses the limitations of the standard assessment of cardiovascular function, and adjunctive monitoring modalities that may be used to enhance the accuracy and timely implementation of therapeutic strategies to improve tissue oxygenation.

Pharmacologic Approach to Heart Failure in Children by Sebastian C. Tume, Jason Goldberg, Silvana Molossi, Ronald A. Bronicki (117-120).
Heart failure may result from a wide variety of causes and present with varying degrees of severity. In large part patients present with varying degrees of congestion and compromised cardiac output. In this review a pathophysiologic construct is provided to guide the pharmacologic management of acute heart failure that leads to decreased congestion and improved cardiac output. Pharmacologic therapies that are used to treat chronic heart failure are also highlighted and provide the framework for transitioning from acute to preventative pharmacologic strategies.

Acute Kidney Injury in Pediatric Heart Failure by Alyssa Riley, Daniel J. Gebhard, Ayse Akcan-Arikan (121-131).
Acute kidney injury (AKI) is very common in pediatric medical and surgical cardiac patients. Not only is it an independent risk factor for increased morbidity and mortality in the short run, but repeated episodes of AKI lead to chronic kidney disease (CKD) especially in the most vulnerable hosts with multiple risk factors, such as heart transplant recipients. The cardiorenal syndrome, a term coined to emphasize the bidirectional nature of simultaneous or sequential cardiac-renal dysfunction both in acute and chronic settings, has been recently described in adults but scarcely reported in children. Despite the common occurrence and clinical and financial impact, AKI in pediatric heart failure outside of cardiac surgery populations remains poorly studied and there are no large-scale pediatric specific preventive or therapeutic studies to date. This article will review pediatric aspects of the cardiorenal syndrome in terms of pathophysiology, clinical impact and treatment options.

Mechanical Circulatory Support in Children by Iki Adachi, Robert D.B. Jaquiss (132-140).
The field of pediatric mechanical circulatory support has undergone a significant evolution with the advent of devices designed for children and the implementation of new strategies for deployment. With the ongoing shortage of organs the demand for new devices specifically designed for children will only increase. This review discusses the evolution of mechanical circulatory support, available devices, and the implementation of new strategies for their deployment.

Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended.

Diagnostic Cardiac Catheterization in the Pediatric Population by Giannis A. Moustafa, Argyrios Kolokythas, Konstantinos Charitakis, Dimitrios V. Avgerinos (155-162).
Although the utility of diagnostic cardiac catheterization in the clinical setting has diminished over the last years, due to the emergence of noninvasive imaging modalities, such as echocardiography, magnetic resonance imaging and computed tomography, catheterization for diagnostic reasons still constitutes a valuable tool in certain parts in the workup of pediatric heart disease. As a result, awareness of the main aspects of diagnostic catheterization is of great importance for the clinical cardiologist. In this article, the main variables measured and the main actions performed during diagnostic cardiac catheterization in children are discussed.