This third edition of what has now become a well-established textbook in cardiovascular medicine is again edited by Dr Eugene Braunwald with the assistance of 65 other authors who read like a Who's Who of American Cardiology. Since the second edition, 12 new chapters have been added or substituted and others have been significantly revised. The first volume includes Part I on "Examination of the Patient" and Part II on "Normal and Abnormal Circulatory Function." The second volume deals with specific diseases. Part III, "Diseases of the Heart, Pericardium and Vascular System," includes new sections on "Risk Factors for Coronary Artery Disease," "The Pathogenesis of Atherosclerosis," and "Interventional Catheterization Techniques." Part IV, "Broader Perspectives on Heart Disease and Cardiologic Practice," includes new chapters on "Genetics and Cardiovascular Disease," "Aging in Cardiac Disease," and "Cost Effective Strategies in Cardiology." The last 200 pages of the book (Part V) are devoted to

Heart Disease: A Textbook of Cardiovascular Medicine

Aims Risk stratification in Brugada Syndrome (BS) remains challenging. Arrhythmic events can occur life-long and studies with long follow-ups are sparse. The aim of our study was to investigate long-term prognosis and risk stratification of BS patients. Methods and results A single centre consecutive cohort of 400 BS patients was included and analysed. Mean age was 41.1 years, 78 patients (19.5%) had a spontaneous type I electrocardiogram (ECG). Clinical presentation was aborted sudden cardiac death (SCD) in 20 patients (5.0%), syncope in 111 (27.8%) and asymptomatic in 269 (67.3%). Familial antecedents of SCD were found in 184 individuals (46.0%), in 31 (7.8%) occurred in first-degree relatives younger than 35 years. An implantable cardioverter defibrillator (ICD) was placed in 176 (44.0%). During a mean follow-up of 80.7 months, 34 arrhythmic events occurred (event rate: 1.4% year). Variables significantly associated to events were: presentation as aborted SCD (Hazard risk [HR] 20.0), syncope (HR 3.7), spontaneous type I (HR 2.7), male gender (HR 2.7), early SCD in first-degree relatives (HR 2.9), SND (HR 5.0), inducible VA (HR 4.7) and proband status (HR 2.1). A score including ECG pattern, early familial SCD antecedents, inducible electrophysiological study, presentation as syncope or as aborted SCD and SND had a predictive performance of 0.82. A score greater than 2 conferred a 5-year event probability of 9.2%. Conclusions BS patients remain at risk many years after diagnosis. Early SCD in first-degree relatives and SND are risk factors for arrhythmic events. A simple risk score might help in the stratification and management of BS patients.

A score model to predict risk of events in patients with Brugada Syndrome.

The cardiac sodium channel gene SCN5A and its gene product NaV1.5: Role in physiology and pathophysiology.

The SCN5A gene encodes the alpha subunit of the main cardiac sodium channel Nav1.5. This channel predominates inward sodium current (INa) and plays a critical role in regulation of cardiac electrophysiological function. Since 1995, SCN5A variants have been found to be causatively associated with Brugada syndrome, long QT syndrome, cardiac conduction system dysfunction, dilated cardiomyopathy, etc. Previous genetic, electrophysiological, and molecular studies have identified the arrhythmic and cardiac structural characteristics induced by SCN5A variants. However, due to the variation of disease manifestations and genetic background, impact of environmental factors, as well as the presence of mixed phenotypes, the detailed and individualized physiological mechanisms in various SCN5A-related syndromes are not fully elucidated. This review summarizes the current knowledge of SCN5A genetic variations in different SCN5A-related cardiac disorders and the newly developed therapy strategies potentially useful to prevent and treat these disorders in clinical setting.

/pdf/scn5a-variants-association-with-cardiac-disorders-16kg59ejh4.pdf

SCN5A Variants: Association With Cardiac Disorders.

Brugada syndrome is an inherited disease characterized by an increased risk of sudden cardiac death owing to ventricular arrhythmias in the absence of structural heart disease. Since the first description of the syndrome >20 years ago, considerable advances have been made in our understanding of the underlying mechanisms involved and the strategies to stratify at-risk patients. The development of repolarization-depolarization abnormalities in patients with Brugada syndrome can involve genetic alterations, abnormal neural crest cell migration, improper gap junctional communication, or connexome abnormalities. A common phenotype observed on the electrocardiogram of patients with Brugada syndrome might be the result of different pathophysiological mechanisms. Furthermore, risk stratification of this patient cohort is critical, and although some risk factors for Brugada syndrome have been frequently reported, several others remain unconfirmed. Current clinical guidelines offer recommendations for patients at high risk of developing sudden cardiac death, but the management of those at low risk has not yet been defined. In this Review, we discuss the proposed mechanisms that underlie the development of Brugada syndrome and the current risk stratification and therapeutic options available for these patients.

Pathogenesis and management of Brugada syndrome.

BACKGROUND Active fixation pacing leads with silicon cylinder tips have been used for their safety and flexibility. Measurement of baseline sensing/pacing characteristics before fixation of helix helps to identify the optimal pacing site, but we encountered difficulties in making these measurements despite multiple attempts with the model LPA 1200M lead. To identify the cause and overcome this complication, we compared 4 different retractable active fixation lead models, which enabled baseline sensing/pacing measurements before extension of helix. METHODS AND RESULTS: We immersed 4 different lead tips and rings in a 0.18% saline solution, and measured the lead impedance before and after flushing of air bubble visible inside the lead tip. Before evacuation of the air bubble, the impedance of the model LPA 1200M lead was >4,000 Ω in 8 out of 10 measurements, although that of the other leads was within the measurable range. After evacuation of the air bubble, the lead impedance returned to within the measurable range. There was no prominent change in the impedance of the metal cylinder tip lead. CONCLUSIONS Air bubbles may interfere with the measurement of baseline sensing/pacing characteristics before active fixation of pacing leads with cylindrical silicon tips. In the case of high impedance beyond the measurable range before extension of helix, the measurement should be repeated after fixation into the myocardium before suspecting lead dysfunction.

Pacing and sensing interference by air bubble surrounding the non-extended helix of intact active fixation lead.

A man in his 70s was admitted to undergo catheter ablation for ventricular tachycardia (VT). He had previously suffered an acute myocardial infarction due to left circumflex artery (LCX) occlusion. Percutaneous coronary intervention (PCI) had been performed but without sufficient revascularization (Fig. 1a, b). In addition, an implantable cardioverter defibrillator (ICD) had been installed due to VT. As the patient was scheduled to undergo catheter ablation with transseptal approach for VT, we performed transesophageal echocardiography (TEE) to evaluate the LA. Surprisingly, TEE detected a thrombus in the LA appendage despite the patient exhibiting a sinus rhythm (Fig. 1c). TEE also detected clear A waves in the mitral flow (Fig. 1d). Active LA ejection fraction [100 9 (LAVpreA LAVmin)/LAVpreA] was 39.3 %, which indicated preserved contraction of the whole LA [3]; however, the A waves in the LA appendage were extremely weak (Fig. 1e) in comparison to normal A waves (Fig. 1f), which suggests LA appendage dysfunction. We retrospectively reviewed coronary angiography (CAG) and noted total obstruction of the LA branch late after the PCI (Fig. 1a, b, white arrows). ICD memory confirmed the absence of atrial fibrillation and coagulation parameters were normal. Based on these, the catheter ablation was postponed, and anticoagulation therapy was started.

Left atrial appendage thrombus in a patient with sinus rhythm and left atrial appendage dysfunction.

Background— Sick sinus syndrome (SSS) is a common arrhythmia often associated with aging or organic heart diseases but may also occur in a familial form with a variable mode of inheritance. Despite the identification of causative genes, including cardiac Na channel ( SCN5A ), the pathogenesis and molecular epidemiology of familial SSS remain undetermined primarily because of its rarity.

Methods and Results— We genetically screened 48 members of 15 SSS families for mutations in several candidate genes and determined the functional properties of mutant Na channels using whole-cell patch clamping. We identified 6 SCN5A mutations including a compound heterozygous mutation. Heterologously expressed mutant Na channels showed loss-of-function properties of reduced or no Na current density in conjunction with gating modulations. Among 19 family members with SCN5A mutations, QT prolongation and Brugada syndrome were associated in 4 and 2 individuals, respectively. Age of onset in probands carrying SCN5A mutations was significantly less (mean±SE, 12.4±4.6 years; n=5) than in SCN5A -negative probands (47.0±4.6 years; n=10; P <0.001) or nonfamilial SSS (74.3±0.4 years; n=538; P <0.001). Meta-analysis of SSS probands carrying SCN5A mutations (n=29) indicated profound male predominance (79.3%) resembling Brugada syndrome but with a considerably earlier age of onset (20.9±3.4 years).

Conclusions— The notable pathophysiological overlap between familial SSS and Na channelopathy indicates that familial SSS with SCN5A mutations may represent a subset of cardiac Na channelopathy with strong male predominance and early clinical manifestations.

Sodium Channelopathy Underlying Familial Sick Sinus Syndrome With Early Onset and Predominantly Male Characteristics

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Pacing and sensing interference by air bubble surrounding the non-extended helix of intact active fixation lead.

Left atrial appendage thrombus in a patient with sinus rhythm and left atrial appendage dysfunction.

Sodium Channelopathy Underlying Familial Sick Sinus Syndrome With Early Onset and Predominantly Male Characteristics