Heart Failure in Pediatric Patients

Mohammad El Tahlawi

• Publisher: Bentham Science Publishers
• Year: 2020
• ISBN:
  9789811410901
• Topic: Medizin
• Subtopic: Kardiologie

Pediatric patients require special attention for treating their cardiac conditions and preventing heart failure. Treatment for heart failure in children may involve professionals from multiple medical disciplines. Heart Failure in Pediatric Patients describes the pathophysiology, classification and clinical presentation of heart failure in pediatric populations with an emphasis on infants with congenital heart disease. Readers will learn about different modes of clinical investigations for pediatric heart patients as well as heart failure in conditions of hypertrophic cardiomyopathy. The book also presents chapters on the management of heart failure including surgery in critical conditions. This book explains concepts with interesting images and videos that illustrate and accurately describe cases. it answers the needs of cardiology learners at different levels; undergraduate, postgraduate, specialists and allied professionals who will be able to benefit from the perspective of several cardiologists working at different regional medical centers

Role of Cardiac Imaging in Heart Failure

Ahmed Aljizeeri^*, Ahmed Alsaileek, Mouaz H. Al-Mallah

King Abdulaziz Cardiac Center, King Abdulaziz Medical City-Riyadh, Riyadh, Kingdom of Saudi Arabia

Abstract

Non-invasive cardiac imaging plays a pivotal role in the contemporary care of heart failure. It has a tremendous potential for better comprehension of the mechanism of heart failure, detection of subclinical disease, assessment and classification of the current state of the established disease and provision of insights regarding prognosis and response to therapy. Cardiac magnetic resonance (CMR), cardiac computed tomography (CCT) and nuclear cardiology provide robust diagnostic and prognostic information. CMR provides the most comprehensive information but it is limited by the availability. Nuclear cardiology, particularly positron emission tomography (PET), provides high diagnostic yield and has exceptional potential in molecular imaging, but is limited by the ionizing radiation and availability. CCT has an established role in the diagnosis of coronary artery disease and an evolving role in tissue characterization, but like nuclear cardiology, it is limited by associated radiation exposure. This chapter discusses the role of CMR, CCT and nuclear cardiology in the management of heart failure.

Keywords: Cardiac Computed Tomography, Cardiac computed Tomography Angiography, Cardiomyopathy, Cardiovascular Mgnetic Resonance, Coronary Artery Disease, Myocardial Delayed Enhancement, Diastolic Dysfunction, Ejection Fraction, Gated SPECT, Heart Failure, Late Gadolinium Enhancement, Micro-Vascular Obstruction, Myocardial Function, Myocardial Innervation, Myocardial Perfusion, Myocardial Viability, Nuclear Cardiology, Positron Emission Tomography, Radionuclide Angiography, Single Photon Emission Tomography.

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^* Corresponding author Ahmed Aljizeeri: King Abdulaziz Cardiac Center, King Abdulaziz Medical City-Riyadh, Riyadh, Kingdom of Saudi Arabia; Tel: [phone]; Ext: 10485; E-mail: [email protected]

INTRODUCTION

Nowadays, cardiac imaging plays a pivotal role in the evaluation of patients with heart failure. It is used in the initial evaluation, diagnosis, prognostication and choice of medical and surgical therapy of heart failure. Its role has been consistently emphasized by the international scientific societies guidelines of

heart failure management [1, 2]. Moreover, the role of cardiac imaging is expected to increase with the current epidemic of heart failure as a result of aging population and recent advances and improvement in the care of coronary artery disease [3, 4]. 2-Dimensional echocardiography remains the first diagnostic modality for the assessment of heart failure. However, the acoustic window, geometric assumption in quantification of the left ventricular ejection fraction and inability to detect minute changes in ejection fraction are known limitations of echocardiography that are not seen in other imaging modalities. This chapter discusses the role of cardiovascular magnetic resonance (CMR), Cardiovascular Computed Tomography (CCT) and Nuclear Scintigraphy in the management of patients with heart failure and reduced as well as preserved ejection fraction.

CARDIOVASCULAR MAGNETIC RESONANCE IMAGING

In recent years, Cardiovascular Magnetic Resonance (CMR) has emerged as an important tool in the evaluation and quantification of ventricular size and function, and myocardial viability in heart failure. The precise quantification, nonuse of ionized radiation and the ability for tissue characterization give CMR a superior role over the other imaging modality.

CMR Techniques and Protocols

CMR has a wide range of clinical applications in contemporary cardiac care. It has an established role in the anatomical evaluation of various cardiac structures, including cardiac chambers, valves, pericardium and major vessels. It can help in the assessment of ventricular function and detection of ischemic heart disease [5, 6].

Different forms of protocols are employed to obtain image sequences to evaluate different components of the heart. Frequently used sequences include cine images to evaluate the size and function of the ventricles as well as wall motion, edema images to evaluate the presence of myocardial edema which usually denotes an acute process and delayed enhancement images to evaluate myocardial injury [7]. A T2* image is a sequence that evaluates the local magnetic field inhomogeneity that results from iron deposition within the myocardium seen in certain cardiomyopathies. The delayed enhancement images are obtained after administration of an intravenous gadolinium-based contrast agent (GBCA) [8]. CMR stress myocardial perfusion can be performed with either dobutamine or a vasodilator agent during which GBCA is injected at peak stress or hyperemia [7]. GDBA is also used for magnetic resonance angiography, although its role in coronary angiography is limited [9]. Flow quantification sequences are used to evaluate and grade the severity of valvular regurgitation [10, 11].

Although CMR exam utilizes the properties of the nuclei, it does not alter its structure since it does not involve the use of ionizing radiation. Therefore, the use of CMR can be performed repeatedly even at a young age without the risk of future development of malignancy. Moreover, the GBCA does not affect the kidney function; however, GBCA is contraindicated in patient with severe renal dysfunction (glomerular filtration rate < 30 ml/min/1.73 m²) or patients on heamodialysis due to possibility of developing Nephrogenic Systemic Fibrosis (NSF), a rare and serious condition characterized by fibrosis of the skin, eye and joint following exposure to GBCA [12]. Finally, care should be taken while performing CMR in patients with pacemaker and automated implantable cardiac defibrillator (AICD). The magnetic field may cause heating of the implanted leads or may result in alteration of the programming of these devices [13]. Newer devices, however, are CMR compatible and therefore, allow performing the CMR study with some precautions [14].

Heart Failure with Reduced Ejection Fraction

Heart failure is a clinical syndrome that manifests irrespective of left ventricular ejection fraction (LVEF). Two clinical entities have been described in heart failure patients; heart failure with reduced ejection fraction (HFrEF), LVEF ≤ 40% also known and systolic dysfunction and heart failure with preserved ejection fraction (HFpEF), LVEF ≥50% also known and diastolic heart failure (1). Quantification of LVEF is essential in the proper classification and prognostication of HF paients [15]. In fact, precise quantification of LVEF is crucial in clinical decision making in regards to medical and device therapy in patients with HFrEF [16, 17]. Two-dimensional echocardiography (2D echo) is conventionally used in the estimation of LVEF. However, 2D echo has its limitation in evaluation of the LVEF including geometric assumption, inter-observer variability in addition to inherent limitation of poor acoustic window in some patients [18, 19]. CMR has emerged as an accurate alternative to overcome these shortcomings.

CMR and Quantification of Ventricular Volumes and Systolic Function

The high spatial resolution, excellent endocar...