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Neural and Spinal Stimulation

Acknowledgment: This work was supported by the Research Grants Council of Hong Kong, General Research Fund (No. HKU 7801/10M, HKU 7811/11M). Introduction Heart failure (HF) is a substantial cause of mortality, morbidity, and health care expenditure worldwide. The burden of HF is enormous; up to 5.8 million patients in the USA and over 23 million patients worldwide suffer from HF. The lifetime risk of developing HF…

The Biological Pacemaker

In October 1958, the first fully internalized pacemaker was implanted at the Karolinska Institute in Sweden. Within hours, the unit ceased to function, or as Senning wrote in a retrospective account “at 2 am the pacemaker became silent.” When searching Medline with the key words “implantable pacemaker,” the first five citations dating from 1960 onward are case reports of various implants. The sixth publication, dated 1962,…

Principles and Applications of Computer Modeling in Patients With Devices

Introduction Computer modeling of heart function has emerged as a powerful tool in the study of heart rhythm and pump disorders. Biophysically detailed cardiac simulations can explain experimental observations and help reveal how organ-scale arrhythmogenic phenomena (ectopic heartbeats, conduction failure, electrical turbulence, etc.) and contractile dysfunction emerge from pathologic effects at the tissue, cell, and protein levels. This extensive “virtual heart” methodology has been built upon…

Implantable Cardioverter-Defibrillators in Inherited Arrhythmia Syndromes

General Introduction Inherited cardiac arrhythmia syndromes may predispose individuals to sudden cardiac death (SCD) as a consequence of an inherited genetic abnormality affecting key proteins of the heart. Traditionally, these genetic disorders are categorized as inherited cardiomyopathies, including hypertrophic cardiomyopathy, inherited dilated cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy, which are associated with structural heart disease, and inherited primary electrical diseases, including long QT syndrome, Brugada syndrome,…

Leadless Pacing

Implantable cardiac pacing was born in 1958 and has never stopped evolving since. The contribution of new advances has been dramatic in this development, especially over the last 25 years, because of the introduction of electronics and the progress in battery technology. However, the physical structure of the system remained the same: a can containing the battery and the electronic circuit is connected to the heart…

Pacing and Defibrillation Use in Pediatric Patients

Permanent cardiac pacemakers and implantable cardioverter defibrillators have been used in children for over half a century. There are several important differences in device usage between children and adults. Children are not only physically smaller than adults, but they also have different underlying cardiac diseases and face a longer lifetime of therapy. Therefore differences exist not only in selection of the optimal pacing system, but also…

Cardiac Resynchronization Therapy

The number of patients with chronic heart failure is increasing rapidly throughout the industrialized economies of the world. The majority of the expense for the management of patients with heart failure (HF) is mostly related to hospitalizations. In the United States, there are not only about 1 million HF hospitalizations yearly but also 300,000 HF deaths; similar numbers are expected in Europe. These deaths are caused…

Subcutaneous and Epicardial Defibrillators

Implantable cardioverter-defibrillators (ICDs) are the most effective means for treatment of ventricular arrhythmias and prevention of sudden cardiac death. In their early use, ICDs were implanted for secondary prevention in those patients who were survivors of sustained ventricular arrhythmias or sudden cardiac arrest (SCA). Many of these early systems consisted of larger generators implanted intra-abdominally and connected to surgically implanted epicardial patches. The use of ICDs…

Defibrillation Therapy

Over the last few decades cardiovascular mortality and sudden cardiac death (SCD) have gradually declined due to improvements in management of patients at risk with advent of primary coronary interventions, widespread use of statins, angiotensin-converting enzyme (ACE) inhibitors, and β-blockers. However, SCD remains the major challenge as about 300,000 to 350,000 cases per year occur in the United States. The landmark study of Bayes de Luna…

Pacing in Reflex (Neurally-Mediated) Syncopes

The Clinical Spectrum of Reflex Syncopes Reflex syncope (synonym: neurally-mediated [reflex] syncope ) refers to a reflex response that, when triggered, gives rise to vaso-/venodilation and/or bradycardia; however, the contribution of each of these two factors to systemic hypotension and cerebral hypoperfusion may differ considerably among affected individuals and may even differ in the same patient at different times. As all forms of reflex syncope share…

Atrioventricular Conduction System Disease

Anatomy The sinus (or sinoatrial, SA) node lies near the junction of the superior vena cava and the right atrium. The sinus node is supplied by the sinus nodal artery, which originates from the proximal few centimeters of the right coronary artery (RCA) in about 55% of human subjects and from the proximal few centimeters of the left circumflex (LCx) artery in the remainder ( Fig.…

Pacing for Sinus Node Disease

Sinus node disease (SND) is the most common indication for a cardiac pacing system. SND increases exponentially with age and occurs in 1 of every 600 cardiac patients older than 65 years. In an analysis of a community-based general population aged ≥45 years, the incidence rate of SND was reported to be 0.8 per 1000 person years, increased with age, and was similar in men and…

Electronic Magnetic Interference and Magnetic Resonance Compatibility

Introduction The implantation of permanent pacemakers (PPMs) and implantable cardioverter-defibrillators (ICDs) for the treatment of bradyarrhythmia and tachyarrhythmia has increased significantly over the past 30 years. In a review of the National Inpatient Sample, researchers found that 2.9 million PPMs were implanted in patients in the United States between 1993 and 2009. The National ICD Registry report states that there had been over 800,000 ICDs implanted…

Leads and Electrodes for Cardiac Implantable Electronic Devices

Leads connect the pulse generator of a cardiac implantable electronic device (CIED) to sites within the body to form an electric circuit ( Fig. 11-1 ). Leads contain five categories of basic components (electrodes, conductors, insulation materials, fixation mechanisms, and connector pieces), each with its own functional requirements and design features ( Table 11-1 ). The electrodes interact with biological tissues through body fluids and should…

Sensors for Implantable Cardiac Pacing Devices

Implantable sensors monitor changes in the body's physiologic conditions. Detection of physiologic changes may be used to modulate the pacing rate of a rate-adaptive pacing system so that the pacing rate is optimized to meet the requirements during exercise and other physiologic needs. This chapter reviews the basic principles and types of sensors that have been investigated in this clinical application. Currently, the sensing of body…

Lead Connection Systems and Standards for Cardiac Implantable Electronic Devices

Cardiac implantable electronic devices (CIEDs), first used in 1958, have become highly sophisticated therapeutic tools for the management of bradyarrhythmias, tachyarrhythmias, and more recently, cardiac resynchronization therapy. The implanted system comprises cardiac leads connected to a generator containing a power source and electronic mechanisms. The coupling of the generator to the cardiac leads requires a connector system that allows current to be transmitted with minimal electrical…

Power Sources and Capacitors for Pacemakers and Implantable Cardioverter-Defibrillators

Introduction This chapter is about batteries and capacitors used to power pacemakers, defibrillators, and other similar implantable devices. Batteries are active components that convert chemical energy into electrical energy, whereas capacitors are passive and temporarily store energy, often to increase the available power (rate of energy delivery) in an electrical circuit. The purpose of this chapter is to communicate useful information that will help clinicians manage…

Physiology of Cardiac Pacing and Resynchronization

Cardiac pacing significantly improves the survival and quality of life in patients with bradycardia and/or dyssynchrony. When first introduced, pacemakers were simply lifesaving devices that provided a fixed pacing rate during bradycardia. With advances in technology and in our understanding of cardiac physiology, devices have been developed that can mimic normal cardiac automaticity and atrioventricular activation sequence and can approach the normal sequence of ventricular activation.…

Tachycardia Termination by Shocks and Pacing

Introduction The burden of tachyarrhythmias has been well described, both in the United States and around the world. Sudden cardiac death is responsible for an estimated 184,000 to 400,000 deaths annually in the United States alone. Of these, the majority are due to ventricular tachyarrhythmias such as ventricular tachycardia (VT) and ventricular fibrillation (VF). Even under the best of circumstances, when the arrest is witnessed and…

Device-Based Modulation of the Autonomic Nervous System

Introduction Rapid advances in the field of detection and modulation of electrical signals within the nervous system have led to the development of a new class of pacing strategies to modulate the nervous system regulating the heart and beyond. Notably, neuromodulation of the peripheral nervous system has attracted considerable attention because the peripheral nerves are more easily targeted, and they control specific organ functions impacted in…