HRCR Rare Diseases Article Collection
Carotid sinus syndrome treated by cardioneuroablation: Is sinus node denervation enough? Insights from a syncope recurrence reportCardioneuroablation (CNA) has been proposed as an alternative treatment for patients with refractory vasovagal syncope (VVS), functional atrioventricular block (AVB), or functional bradyarrhythmia instead of classical treatment or pacemaker.1 Vagal denervation is achieved by endocardial catheter ablation targeting atrial fibrillation nests (AFN)2 and ganglionic plexus (GP)-related areas. We describe a clinical case of cardioinhibitory carotid sinus syndrome (CSS) treated with CNA, where partial vagal denervation was achieved over sinus node.
To the Editor—Concealed His or Purkinje extrasystoles?I read with interest the case report by Ho and colleagues.1 I would like to present arguments suggesting alternative diagnoses.
Improved symptoms, exercise capacity, and homogeneity of cardiac deformation through conduction system pacing in a patient with symptomatic left bundle branch blockPainful left bundle branch syndrome is a clinical entity consisting of exertional angina and rate-dependent left bundle branch block (LBBB), affecting patients of all age and sex.1 Because of potentially coexisting other cardiac diseases (ie, cardiomyopathy, coronary artery disease) that may mimic both LBBB and symptoms, the true prevalence is unknown, but fewer than 60 cases have been reported so far.1 Diagnostic criteria do not officially exist, but simultaneous onset of LBBB and angina during exercise test support the diagnosis.
Electrophysiology and surgery intertwined in complex treatment of Ebstein’s anomaly in childhoodEbstein’s anomaly, a rare and highly variable congenital heart defect,1 still presents a treatment challenge. The currently used cone repair of the tricuspid valve has carried favorable results in suitable patients.2 Arrhythmogenic substrates including accessory pathways3,4 and right bundle branch block5 associated with electromechanical ventricular dyssynchrony present additional therapeutic targets. We present a patient with Ebstein’s anomaly of tricuspid valve and Wolff-Parkinson-White syndrome in whom joint electrophysiological and surgical interventions were used to address all major disease components.
Epicardial multisite conduction blocks detected by equispaced electrode array and omnipolar technology in Brugada syndromeBrugada syndrome (BrS) is an inherited channelopathy linked to an increased risk of developing malignant ventricular arrhythmias and sudden cardiac death in otherwise healthy individuals.1 Currently, implantable cardioverter-defibrillator (ICD) is still the mainstay of treatment for BrS,1 but for patients experiencing recurrent ICD shocks despite optimal medical therapy, radiofrequency (RF) transcatheter ablation of the arrhythmogenic substrate is an available option with promising results.2–5 Although there is a generalized consensus in considering the right ventricular outflow tract (RVOT) epicardium as the locus harboring the pathologic substrate, the exact pathogenesis of BrS is still a matter of debate.
Localized intramural reentry confined within the ventricular septum in lamin cardiomyopathyHigh-resolution electroanatomic mapping systems have greatly improved the ability to characterize the size and dimensions of the reentrant circuit responsible for human ventricular tachycardia (VT). The minimal dimension of critical isthmus regions may be less than 1 cm in more than 25% of circuits mapped.1 Despite advanced, detailed simultaneous epicardial and endocardial mapping, detection of intramural circuit components remains challenging. Epicardial mapping through coronary venous branches has gained popularity owing to refinement of mapping catheters and novel use of transcoronary venous ethanol.
Lyme carditis presenting with an incessant atrioventricular nodal reentrant tachycardia masking a variable atrioventricular blockLyme disease is a common tick-borne illness with a high prevalence in the Northeast region of the United States.1 It is an infection caused by Borrelia burgdorferi, a gram-negative spirochetal bacterium carried by infected ticks such as Ixodes scapularis. They are found outdoors, latched onto blades of grass until they can attach to a host. If not treated early, serious complications can develop. Since Lyme antibodies can take several weeks to develop, false-negatives can arise in about 50% of cases when testing is done too early.
The man in the mirror: Biventricular device implantation in a patient with dextrocardia with situs inversus totalisThe population of individuals with adult congenital heart disease is expanding as advances in surgical and medical management allow patients to live into adulthood. Consequently, these patients are developing other cardiovascular diseases, such as arrhythmias and heart failure, later in life. Procedures involving congenital anatomic variations are becoming more commonplace, and operators must become familiar with them. One such congenital abnormality, dextrocardia, involves the reversal of the base–apex axis of the heart caudally and to the right.
Open-window mapping of atriofascicular tachycardiaAccessory atrioventricular pathway (AP) conduction is found in 33% of patients with Ebstein anomaly, including atriofascicular (AF) pathways in 5%–8%.1 AF pathways typically conduct anterograde only, with decremental conduction properties analogous to the atrioventricular node (AVN), and participate almost exclusively in antidromic atrioventricular reciprocating tachycardia (AVRT).1,2 Ablation of AF APs may be challenging in such patients due to the deviation from normal anatomic structure, potential for multiple APs, difficulty obtaining catheter stability, hemodynamic instability in tachycardia, and concerns for catheter-induced mechanical conduction block.
Masquerade: An unusual accessory pathway with ventricular insertion at the right–left sinus of Valsalva mimicking outflow tract ventricular tachycardiaAlthough rare, an accessory pathway (AP) can have a ventricular insertion in the region of the aortic sinuses of Valsalva.1–4 This can be difficult to diagnose and may resemble outflow tract ventricular tachycardia (VT).4 Despite the existence of various algorithms that can differentiate wide-complex supraventricular tachycardia (SVT) from VT, these conditions may be impossible to differentiate based on surface QRS morphology alone.5,6
A case of long QT syndrome type 2 that developed torsades de pointes two days after the initiation of oral β-blocker therapyCongenital long QT syndrome (LQT) is a potentially lethal hereditary arrhythmic disorder that can cause syncope and sudden cardiac death owing to polymorphic ventricular tachycardias in association with prolonged QT intervals in electrocardiograms (ECGs), termed as “torsades de pointes” (TdP). The prevalence of LQT is reported to be 1 in 2000, and genetic testing reveals mutations in cardiac ion channel–related genes in about 70% of the cases. Variants in the 3 genes, KCNQ1, KCNH2, and SCN5A, account for approximately 90% of LQT cases, referred to as LQT type 1, 2, and 3 (LQT1, LQT2, and LQT3), respectively.
One family’s clinical odyssey from evolving phenotypic and genotypic knowledge of catecholaminergic polymorphic ventricular tachycardia and long QT syndromeLife-threatening arrhythmias in apparently healthy individuals can be due to diverse heritable cardiac channelopathies.1 Ongoing advances revealing the underlying pathophysiology and genotype-phenotype associations are constantly evolving our approaches to diagnosis and management of these clinical entities.1–3 In some cases, initial diagnoses prove inaccurate over time, so routine reevaluation of each patient and family member remains an important element of care, with potentially life-altering ramifications.
Presentation and genetic confirmation of long QT syndrome in the fetusLong QT syndrome (LQTS) is an ion channelopathy that may cause life-threatening ventricular arrhythmias resulting in intrauterine death, cardiac arrest, or sudden death at any age.1–3 LQTS is often an inherited condition but may present as a de novo mutation, and its prevalence has been reported as high as 1:2000.4
Exercise-induced arrhythmogenic right ventricular cardiomyopathy: A clinical syndrome in motionExercise-induced arrhythmogenic right ventricular cardiomyopathy (ARVC), a theoretical disease entity, has an unusual history. Lacking a diagnostic gold standard, it is a diagnosis of exclusion built upon a foundation of research compiled for ARVC.
Progressive atrial myocardial fibrosis in a 4-year-old girl with atrial standstill associated with an SCN5A gene mutationAtrial standstill (AS) is a rare cardiac syndrome characterized by the absence of electrical and mechanical activity in the atria. Mutations in the sodium channel α-subunit SCN5A gene have been identified as the cause of arrhythmia syndromes, such as long QT syndrome, Brugada syndrome (BrS), progressive cardiac conduction disease, sinus node dysfunction, atrial fibrillation, and AS.1 Historically, these cardiac sodium channelopathies were considered to be purely electrical disorders. However, with the accumulation of cases, SCN5A mutations also came to be associated with structural disorders involving myocardial fibrosis.
Catheter ablation for persistent atrial fibrillation in an elderly patient with cor triatriatum sinisterCor triatriatum sinister (CTS) accounts for <0.1% of all congenital heart diseases. It is a condition in which the fibromuscular membrane divides the left atrium (LA) into 2 chambers.1 The superior and posterior chambers receive the pulmonary veins, and the inferior and anterior chambers are connected to the left atrial appendage and mitral orifice.2 Pathophysiologically, CTS is similar to mitral stenosis,3 and the symptoms are correlated with pulmonary venous congestion and pressure loading at the right side of the heart.
Exercise-induced arrhythmogenic right ventricular cardiomyopathy: Reverse remodeling with detrainingLong-term exercise training leads to structural cardiac adaptations, collectively referred to as the “athlete’s heart.” While the ventricles both undergo dilation and eccentric hypertrophy, it has been shown that the right ventricle (RV) experiences disproportionate remodeling under intense sports activity.1 Occasionally, the remodeling that occurs in the athlete’s heart may resemble arrhythmogenic right ventricular cardiomyopathy (ARVC), a pathologic cardiomyopathy associated with sudden death.
Hybrid minithoracotomy approach for zero-fluoroscopy epicardial ablation of the arrhythmogenic substrate in Brugada syndromeSince its first description in 1992,1 Brugada syndrome (BrS) has claimed global attention as a remarkable cause of sudden cardiac death in young and otherwise healthy adults because of malignant ventricular tachyarrhythmias (mVT).1,2
Cardiac arrhythmias in primary hypokalemic periodic paralysis: Case report and literature reviewHypokalemic periodic paralysis (HPP) is a rare neuromuscular disorder characterized by episodes of muscle weakness and paralysis accompanied by hypokalemia. Several studies have reported the presence of cardiac arrhythmias, the majority being secondary to hypokalemia-induced changes. However, other studies have described cardiac arrhythmias that cannot be explained by hypokalemia or the diagnosis of HPP. Herein, we describe the case of a pediatric male patient with HPP and recurrent episodes of monomorphic ventricular tachycardia (VT), followed by a systematic literature review on primary HPP and cardiac arrhythmias.
Idiopathic ventricular fibrillation triggered by premature ventricular complexes originating from the false tendon of the left ventricleIdiopathic ventricular fibrillation (VF) is a diagnosis of exclusion when no evidence of a structural or metabolic cause is found. It is a rare cause of sudden cardiac death reported in 6.8% of patients who survive an out-of-hospital cardiac arrest and is more frequently seen in young adults.1 Premature ventricular contractions (PVCs) originating from the Purkinje network can induce polymorphic ventricular tachycardia (PMVT) or VF in rare cases. The electrophysiologic mechanisms, although not completely clear, have been thought to be related to abnormal automaticity and triggered activity.
Successful ablation of an outlet septum ventricular tachycardia in a double-outlet right ventricle patient who underwent an extracardiac Fontan operationArrhythmias are one of the most common causes of death in the late period post Fontan operation1 and are associated with a 3.5% incidence of ventricular tachycardia (VT).2 The extracardiac Fontan (EC-Fontan) has recently become the most commonly used approach in the Fontan operation. In such patients, catheter ablation (CA) is difficult to perform because the venous access to the heart is limited. A transcaval cardiac puncture (TCP) technique for gaining access to the heart chamber has previously been suggested for EC-Fontan patients.
First reported implantation of a VDD leadless pacemaker and a subcutaneous defibrillator in a patient with congenitally corrected transposition of the great arteriesEntirely subcutaneous implantable cardioverter-defibrillators (S-ICD™ system; Boston Scientific Corp, Marlborough, MA) provide effective defibrillation and reduce the risk of infection or lead-related problems.1–3 S-ICD systems may be a valid alternative to transvenous implantable cardioverter-defibrillator (ICD) in patients in whom bradycardia pacing or cardiac resynchronization therapy (CRT) is not required.4,5 The Micra™ AV Transcatheter Pacing System (Medtronic Inc, Minneapolis, MN) is a recently approved leadless pacemaker enabling atrioventricular (AV) synchronized pacing, which may, in theory, compensate the S-ICD’s inability to pace.
Cardiac lymphoma presenting as bradyarrhythmiaCardiac tumors have been a point of interest and controversy since the earliest attempt to categorize them in 1931 by Yater.1,2 Secondary cardiac tumors are 30 times more common than primary cardiac tumors, with an incidence of 1.7%–14% vs 0.001%–0.03% on autopsy.3 Primary cardiac tumors are most commonly benign (70%–80%).3,4 However, of the primary malignant cardiac tumors, lymphoma has been shown to account for 1%–1.6%.5,6 Up to 20% of patients with noncardiac primary lymphoma will exhibit cardiac metastases.
Normalization of ventricular function after cardiac contractility modulation in noncompaction cardiomyopathy heterozygous positive for a pathologic TTN gene variantCardiac contractility modulation (CCM) may be used as an adjunct for the treatment of medically refractory class III chronic systolic congestive heart failure (CHF) with ejection fraction (EF) 25%–45% not indicated for biventricular pacing.1–3 CCM treats CHF through effecting improvement in myocardial cellular calcium handling and with reversal of adverse gene dysregulations.4,5 Enhanced phosphorylation of the giant myocardial protein titin also occurs with CCM, which can improve myocardial relaxation.
Progressive giant cell myocarditis presenting with inappropriate shocks from a subcutaneous defibrillatorGiant cell myocarditis (GCM) is a rare form of myocarditis predominantly affecting young, healthy adults. It is usually characterized by progressive cardiac failure, and ventricular arrhythmias are common.1 Despite treatment with immunosuppression and guideline-directed heart failure therapy, implantable cardioverter-defibrillators (ICDs) are commonly inserted.2 The currently available subcutaneous ICD (S-ICD; Emblem; Boston Scientific, Marlborough, MA) has a high efficacy rate for conversion of ventricular arrhythmias2 and, when compared to transvenous ICDs, has a numerically lower infection rate at the expense of a higher rate of inappropriate shocks.