Chapters authored
Hypertrophic Cardiomyopathy: Treatment, Risk Stratification, and Implantable Defibrillators By Peter Magnusson
Hypertrophic cardiomyopathy (HCM) affects 1:500 individuals, and in majority of cases, a mutation in sarcomere proteins can explain the disease. Phenotype is heterogeneous and thus the prognosis. Many patients suffer from dyspnoea, especially at exercise. Unfortunately, sudden cardiac death (SCD) does occur at all ages and is a major cause of death in young adults. There is no proven pharmacological treatment to reduce hypertrophy or fibrosis, but beta-blockers are first-line treatment. In patients with obstruction, myectomy is preferred in the young, but in older patients, alcohol septal ablation is tried to reduce symptoms and possibly prognosis. Risk stratification of sudden cardiac death is challenging. The major established risk factors are extreme myocardial thickness, non-sustained ventricular tachycardia, unexplained syncope, abnormal exercise blood pressure response, and family history of sudden cardiac death. In 2014, a novel risk calculator was developed that also takes age, outflow gradient, and left atrial seize into account. Implantable defibrillator treatment is effective in HCM, but complications requiring surgery and inappropriate shocks remain a problem.
Part of the book: Cardiomyopathies
Ischemic Cardiomyopathy: Contemporary Clinical Management By Burhan Sheikh Alkar, Gustav Mattsson and Peter Magnusson
Ischemic cardiomyopathy, disease of the heart muscle due to coronary artery disease, is the most common cardiomyopathy. It is often difficult to discern the etiology of heart failure, and often there are multiple underlying causes. Ischemic cardiomyopathy most often presents with a dilated morphology with wall motion defects and a history of previous myocardial infarction or confirmed coronary artery disease. Mechanisms of myocardial depression in ischemia are necrosis of myocardial cells resulting in irreversible loss of function or reversible damage, either short term through myocardial stunning or long term through hibernation. In ischemic cardiomyopathy, echocardiography may be extended with stress testing or other imaging modalities such as myocardial scintigraphy and cardiac magnetic resonance tomography. Coronary angiography is often considered a gold standard; however, other modalities such as positron emission tomography can be needed to detect small vessel disease. Cardiac revascularization, through percutaneous coronary intervention and coronary artery bypass grafting, both in acute coronary syndrome and in stable coronary artery disease, relieves symptoms and improves prognosis. Therapy should aspire to treat ischemia, arrhythmias in addition to heart failure management, which includes device therapy with cardiac resynchronization therapy, implantable cardioverter defibrillators, and mechanical support as bridging or destination therapy in end-stage disease.
Part of the book: Current Perspectives on Cardiomyopathies
The Subcutaneous Implantable Cardioverter-Defibrillator By Peter Magnusson, Joseph V. Pergolizzi and Jo Ann LeQuang
The subcutaneous ICD (S-ICD) represents an important advancement in defibrillation therapy that obviates the need for a transvenous lead, the most frequent complication with transvenous devices. The S-ICD has been shown similarly safe and effective as transvenous ICD therapy, but the two devices are not interchangeable. The S-ICD is only suitable for patients who do not require bradycardia or antitachycardia pacing functionality. In patients with underlying diseases associated with polymorphic ventricular tachycardia and a long life expectancy, an S-ICD may be the preferred choice. Moreover, it is advantageous in the situation of increased risk of endocarditis, i.e., previous device system infection and immunosuppression, including hemodialysis. In patients with abnormal vascular access and/or right-sided heart structural abnormalities, it may be the only option. The S-ICD is bulkier, the battery longevity is shorter, and the device cost is higher, even though remote follow-up is possible. A two- or three-incision implant procedure has been described with a lateral placement of the device and a single subcutaneous lead. The rate of inappropriate therapy for both S-ICD and transvenous systems is similar, but S-ICD inappropriate shocks are more frequently attributable to oversensing, which can often be resolved with sensing adjustments.
Part of the book: Cardiac Pacing and Monitoring
Clinical Indications for Therapeutic Cardiac Devices By Ida Åberg, Gustav Mattsson and Peter Magnusson
Both technology and clinical indications have changed since the first cardiac devices. Choosing the right therapy, or abstaining from it, is the key to good clinical management. Pacemakers effectively reduce symptoms of bradycardia, prevent syncope in patients with sick sinus syndrome, and reduce mortality in high-degree atrioventricular block. Cardiac resynchronization therapy improves symptoms and survival in heart failure patients with reduced ejection fraction and ventricular dyssynchrony. Implantable cardioverter defibrillators terminate life-threatening ventricular arrhythmias and are indicated for the prevention of sudden cardiac death, either as secondary prevention in survivors of ventricular fibrillation or ventricular tachycardia with hemodynamic compromise or as primary prevention due to heart failure with reduced ejection fraction or other miscellaneous diseases. More recently, leadless pacemakers and subcutaneous implantable cardioverter defibrillators have been developed as alternatives in specific conditions.
Part of the book: Cardiac Pacing and Monitoring
Atrial Fibrillation and the Role of Thumb ECGs By Peter Magnusson, Magnus Samuelsson, Joseph V. Pergolizzi Jr, Hani Annabi
and Jo Ann LeQuang
Atrial fibrillation (AF) may be underdiagnosed, and there is much that remains unknown about this prevalent and potentially life-threatening arrhythmia. AF epidemiology has been thwarted in part by the fact that about a third of patients with AF have no symptoms, those with symptoms may experience them intermittently or have vague symptoms, and it can be challenging to capture an episode on a 12-lead ECG, which is required for diagnosis. There are many significant knowledge gaps in our understanding of AF etiology and progression. A new user-friendly device that allows for frequent self-monitoring of the heart rhythm has been introduced. With the thumb ECG, patients can record a tracing multiple times a day. A smartphone app will soon allow them to interact with their healthcare providers about these ECG recordings. An ECG parser will allow for an algorithm-directed, rapid, automatic interpretation of these recordings with high specificity and sensitivity. This may help researchers learn more about the so-called silent AF, AF progression (and possible remission), and risk factors for AF. This technology holds great promise for patient care as well as for research into AF.
Part of the book: Cardiac Pacing and Monitoring
Leadless Pacemakers By Peter Magnusson, Joseph V. Pergolizzi Jr and Jo Ann LeQuang
Leadless or transcatheter pacemakers have recently been introduced to market with important benefits and some limitations. Implanted entirely within the right ventricle, these devices eliminate the need for transvenous pacing leads and pacemaker pockets and thus reduce the risk of infections and lead-related problems. Currently, they offer only VVI/R pacing and they cannot provide atrial sensing, antitachycardia pacing, or AV synchrony. They offer a number of features (such as rate response) and electrogram storage, albeit more limited than in a transvenous system. Real-world clinical data are needed to better comment on projected battery life, which manufacturers suggest will be at least equivalent to transvenous devices. Extracting an implanted leadless pacemaker remains a challenge, although proprietary snare and removal systems are available. However, a leadless pacemaker at end of service may be programmed to OOO and left in place; a revised device may be implanted adjacent. These innovative new devices may have important uses in special populations. Initial data on implant success and adverse events are favorable. Currently, there are two leadless pacemakers available: the Micra™ device by Medtronic and the Nanostim™ device by Abbott (formerly St. Jude Medical).
Part of the book: Cardiac Pacing and Monitoring
Cardiac Implantable Electronic Device-Related Infections By Måns Almqvist, Gustav Mattsson, Robin Razmi and Peter Magnusson
The use of cardiac devices, that is, pacemakers and implantable cardioverter defibrillators, has increased, and the incidence will likely continue to increase due to an aging population with associated risk factors. Unfortunately, this implies an increasing number of complications, including infections. Cardiac device-related infection is a dreaded complication causing both increased morbidity and mortality, and considerable costs. Because of the presence of a foreign body in subcutaneous tissue, vasculature, and the heart, patients with cardiac device systems are at increased risk of endocarditis due to microbial agents. In general, an infected device system should be removed in its entirety. The timing of reimplantation varies due to indication and severity of the infection. Furthermore, the explant procedure may be complicated and should be performed by an experienced team including facilities to handle life-threatening complications. The subcutaneous implantable cardioverter defibrillator or leadless pacemaker can serve as an option in selected cases. This chapter will describe clinical aspects of cardiac device-related infections.
Part of the book: Infective Endocarditis
Anticoagulation in Atrial Fibrillation Patients By Peter Magnusson, Joseph V. Pergolizzi Jr, Randall K. Wolf, Morten Lamberts and Jo Ann LeQuang
Atrial fibrillation (AF) is the most common arrhythmia and may cause thromboembolic events, typically stroke. Advances in pharmacological approaches to anticoagulation and groundbreaking large randomized controlled trials of non-vitamin K antagonist oral anticoagulants (NOACs) have changed the paradigm of anticoagulation therapy. Furthermore, observational studies support the efficacy and safety of NOAC. Few studies address the differences among NOACs, but prescriptions should be based on a thorough understanding of their pharmacological differences, including interactions, side effects, reversibility, and practical approach. In a subset of patients with AF, warfarin may still be the preferable option. Consequently, an individualized approach to oral anticoagulation is crucial.
Part of the book: Epidemiology and Treatment of Atrial Fibrillation
View all chapters