HRCR Rare Diseases Article Collection
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.
Takotsubo cardiomyopathy and Brugada syndrome in a patient with a novel loss-of-function variant in the cardiac sodium channel Nav1.5Takotsubo cardiomyopathy (TTC) is a stress cardiomyopathy characterized by transient left ventricular dysfunction.1 TTC typically presents in postmenopausal women and is triggered by physical or emotional stress, most likely owing to an increased sympathetic activity.1 Symptoms resemble those of an acute myocardial infarction and the patients often present with various electrocardiogram (ECG) changes proposing an alteration in cardiac repolarization.2 Previously, familial clustering of TTC has been described, suggesting a genetic predisposition to TTC.
Exercise-induced Brugada syndrome type 1 patternBrugada syndrome (BrS) is an inherited disorder usually afflicting patients with otherwise structurally normal hearts. Many triggers have been identified that can result in the phenotypic expression of the higher-risk BrS type 1 pattern. These triggers include but are not limited to fever, heightened vagal tone, and sodium (Na) channel blocking agents. Conversion to the type 1 pattern during exercise is unusual and in fact isoproterenol is a treatment for ventricular tachycardia (VT) storm in Brugada syndrome.
Unmasked type 1 Brugada ECG pattern without a fever after a COVID-19 vaccinationBrugada syndrome (BrS) patients are regarded as a high-risk population under the COVID-19 pandemic because infection-induced fevers may unmask a type 1 Brugada electrocardiogram (ECG) pattern potentially leading to lethal ventricular arrhythmias.1 Vaccinations seem to be crucial in BrS patients; however, careful observation and antipyretic drugs are necessary for vaccine-induced fevers.2 Among the enormous number of COVID-19 vaccinations around the world, although the incidence is rare, death events, including sudden cardiac death, after a vaccination have been reported.
Ventricular tachycardia ablation in a patient with Ehlers-Danlos syndromeVentricular tachycardia (VT) is a well-recognized complication of postinfarct-related scar. Catheter ablation is a guideline-recommended therapy in patients with frequent VT episodes. Ablation aims to target regions of slow conduction within ventricular scar that support reentry.1
Late-onset Fabry disease revealed by ventricular tachycardia: A case reportFabry disease (FD) is an X-linked lysosomal storage disorder due to mutations in the GLA gene leading to deficiency of lysosomal α-galactosidase A (α-Gal A). Classic FD causes multiorgan failure, whereas the later-onset phenotype is characterized by predominantly cardiac manifestations. Ventricular arrhythmias are among the complications.1,2
Cardiac sarcoidosis involving the papillary muscle: A case reportSarcoidosis is a granulomatous multisystem disease that is thought to arise from a dysregulated immunological response. A total of 25% of those suffering from sarcoidosis have cardiac involvement on postmortem analysis, but it is clinically apparent in only 5%.1 Isolated cardiac sarcoidosis (CS) has also been described.2 It may manifest as conduction system dysfunction, ventricular arrhythmias, congestive cardiac failure, or sudden cardiac death.3 CS has a predilection for the ventricular myocardium and its clinical presentation may vary from no symptoms to sudden cardiac death.
Malignancies masquerading as device pocket infectionsInfectious complications following cardiac implantable electronic device (CIED) implantation are associated with significant mortality. Establishing the correct diagnosis is important and not all presumed CIED pocket infections turn out to be infections. Rare cases of malignancy mimicking a pocket infection have been described. We present 2 cases of malignancy, initially thought to be a primary CIED pocket infection.
A diagnostic dilemma upon discovery of a left atrial mass using an intracardiac echocardiogramIt is important to discern the nature of any mass that may appear on the left atrial (LA) ridge, or “coumadin ridge,” which is situated between the LA appendage and the left superior pulmonary vein prior to any procedures involving the left atrium. Despite the rarity of the appearance of LA ridge mass, the shape and location are important in distinguishing a cardiac tumor or thrombus.1 In this case report, a mass on the LA ridge was discovered during an intracardiac echocardiogram prior to transseptal puncture for ablation of atrial fibrillation, posing a diagnostic dilemma and leading to a cascade of imaging studies.
Ventricular fibrillation due to a likely pathogenic SOS1 variant: An unrecognized etiology of infantile sudden death?We present the case of a female infant presenting after a ventricular fibrillation arrest found to have ectopic atrial tachycardia (EAT). Evaluation revealed a likely pathogenic variant in SOS1 not previously reported in affected individuals. SOS1 variants are associated with Noonan syndrome, which belongs to a family of related genetic syndromes affecting the RAS/MAPK signaling pathway. To date, this is the first case reported of a ventricular fibrillation arrest in a patient with a RASopathy-related variant prior to development of the typically associated structural cardiac phenotype and may represent a previously unrecognized etiology of sudden death during infancy.
Increased device thresholds with subsequent improvement status post–systemic therapy in a patient with multiple myelomaThe pacemaker device stimulation threshold by definition is the minimal amount of electrical energy required to induce consistent capture outside the refractory period of the heart. The difference between the threshold and the programmed device output reflects the reserve or pacing safety factor.1 It is affected by a multitude of factors, including physiologic variants, use of certain pharmacologic agents, and pathologies such as hypoxia, hypothermia, poorly controlled diabetes, and myocardial ischemia.
Leadless atrioventricular synchronous pacing in Eisenmenger syndromeEisenmenger syndrome is at the extreme end of the phenotypic spectrum of pulmonary arterial hypertension associated with congenital heart disease. Over time, a large nonrestrictive left-to-right shunt provokes progressive pulmonary vascular disease that results in the shunt becoming bidirectional or reversing direction (ie, right-to-left). When the need for pacing arises, transvenous leads are generally considered contraindicated owing to a prohibitively high risk of paradoxical thromboembolism.
A case of cardiac sarcoidosis with concurrent myocardial ischemiaSarcoidosis is a rare multisystem disease of unknown etiology affecting 10–40 in 100,000 population, characterized by granulomatous inflammation.1 It has a diverse set of presentations ranging from diffuse to localized disease and can have either acute or chronic clinical course with multiple organ involvement.1 Classically, lungs are the most commonly affected organ, but systemic, dermatologic, and cardiac involvement also occur. Specifically, 20%–30% of sarcoidosis patients have been observed to have cardiac involvement in an autopsy1; however, only about 5% have a symptomatic presentation with cardiac disease.
Ventricular tachycardia as the initial presentation of missed Kawasaki disease in a teenagerVentricular tachycardia (VT) has been reported in acute cases of Kawasaki disease. VT secondary to ischemic sequelae is also a known long-term complication of Kawasaki disease, typically seen 2 decades after initial disease onset.1,2 We report the first case, to our knowledge, of an otherwise healthy teenager with sustained VT as the presenting symptom for missed Kawasaki disease and describe the management approach by our team that had not considered Kawasaki disease in the differential. This case broadens our understanding of Kawasaki disease presentations in the young and timing of long-term sequelae.