Sinus Node Dysfunction Research Articles

Midterm postoperative outcomes of different types of surgical reconstruction of sinus venosus atrial septal defects with anomalous pulmonary venous connection: The Results of Prospective Cohort Study.

Sinus venosus atrial septal defects (SVASDs) constitute a substantial part of atrial septal defects and are usually characterized by anomalous pulmonary venous connection (APVC), causing complications like sinus node dysfunction and arrhythmias. Several surgical approaches are used for treating SVASDs in pediatric patients, including single- and two-patch techniques. The study aimed to prospectively evaluate and compare the safety and efficacy of these two methods with different follow-up periods. Ten patients aged 1-8 years with SVASDs and partial APVC were enrolled in the study at Bhanubhai and Madhuben Patel Cardiac Centre, Karamsad, India, between December 2018 and October2021. The single-patch (sandwich-patch) technique was used in two patients, whereas the two-patch (dual-patch) technique with autologous pericardium was used in seven. Safety was assessed as the absence of complications in the follow-up periods of 6 months, 1, and 2 years, whereas efficacy was estimated by the preserved sinus rhythm and the development of arrhythmias. Electrocardiographic and echocardiographic methods were used to evaluate both parameters. No deaths, reoperations, pulmonary vein, and superior vena cava (SVC) stenosis or phrenic nerve palsy were observed among the 10 patients in the three follow-up periods. Sinus rhythm was arrested in two of the seven patients who underwent two-patch repair, whereas no rhythm disturbances occurred in those who underwent single-patch repair. Both techniques used in SVASD repair with autologous pericardium proved to cause the smaller rate of complications in midterm postsurgical phase. However, there is a potentially great risk of the development of sinus node malfunction after the application of the two-patch technique. Therefore, methods avoiding sinus node interference are preferred in patients with partial APVC involving SVC.

764 CARDIONEUROABLATION OF VAGALLY MEDIATED BRADYARRHYTHMIA: A SINGLE-CENTER EXPERIENCE

Abstract Background Cardioneuroablation (CNA) is a novel catheter-ablation technique for the treatment of vagally-mediated bradyarrhythmia including vaso-vagal syncope (VVS), functional atrioventricular block (AVB) and sinus node dysfunction (SND). CNA aims to blunt the cardioinhibitory reflex by eliminating postganglionic parasympathetic neurons in the atrial wall and ganglionated plexi (GPs). Early-phase studies have shown promising results, but clinical evidence remains limited. Purpose We present our single-center experience with CNA in the setting of VVS, symptomatic functional AVB, and SND. Methods Baseline and procedural characteristics, procedure-related complications, and clinical outcomes were collected in patients who underwent CNA from December 2018 to July 2022. The procedural workflow included an electroanatomic mapping-guided ablation strategy, which combines the bi-atrial 3D mapping with endocardial atrial bipolar electrograms (EGM), specifically targeting high-amplitude fractionated EGM. Results A total of 14 CNA procedures were performed in our center. Ablation indication was mainly VVS (57%), followed by AVB (29%) and SND (14%). Syncope was the most common symptom in our cohort (71%, burden of 7 per person-lifetime). Patients were young (43±16 years) and without structural heart disease (LVEF 58±4 ml, LAD 31±7 mm). Procedures were performed under general anesthesia, mean procedure time was 102±42 min, with minimal fluoroscopy dose (2.7±1.8 Gy/cm2). We observed 1 instance of post-ablation pericarditis and 2 sinus tachycardia which required medical treatment; no major adverse events occurred. Heart rate increased after ablation in all the patients, with a mean RR interval shortening of 28% and no further increase after atropine administration. Two patients had a recurrence at a median follow-up of 251 days (IQR: 118-536), both cases were syncopal events without documentation at loop-recorder of sinus bradycardia or atrial bradyarrhythmia. Conclusions CNA may be an alternative to pacemaker implantation in young, highly symptomatic patients, refractory to conventional therapies and without structural heart disease. Ablation is reasonably safe in experts’ hands, especially if compared with the long-life risk of device-related complications. Further large-scale randomized studies are needed to support these findings.

772 SCREENING FOR ANDERSON-FABRY DISEASE IN RELATIVELY YOUNG PATIENTS WITH UNEXPLAINED CONDUCTION DISORDERS REQUIRING PACEMAKER IMPLANTATION

Abstract Background Anderson-Fabry Disease (AFD, OMIM 301500) is a rare X-linked lysosomal storage disorder caused by GLA gene mutation resulting in a deficit or absent activity of the α-galactosidase A enzyme (α-Gal A). This deficiency involves the impossibility of cleavage of glycophospholipids, resulting in an intralisosomal accumulation of them in different tissues. Due to an incidence of 1 in 80000, AFD is considered the second most common glycosphingolipid storage disorder after Gaucher disease. Cardiac manifestations include left ventricular hypertrophy (LVH) and arrhythmias. The rate of pacemaker implantation (PMI) in AFD has been described to be 25 times higher than in the general population, and the requirement of PMI has been reported to be as high as 8% in some AFD series. In this context, the presence of conduction abnormalities in young patients may suggest an undiagnosed AFD.1 Therefore, early diagnosis is important in AFD because appropriate therapies seem to be more effective when initiated promptly. Purpose Our aim is to detect AFD among relatively patients with unexplained conduction disturbances requiring PMI, not submitted to newborn screening. Methods Among 650 patients afferent to our ambulatory for routinary pacemaker follow-up, we considered a selected population with diagnosis of sinus node dysfunction or atrioventricular block (confirmed by atrial pacing rate ≥ 60% or ventricular pacing percentage ≥ 80%) and an age, at the time of PMI, ranging between ≥40 and ≤70 years old. The exclusion criteria were: patients with previous myocardial infarction; patient whit known cardiac disease (such as hypertrophic cardiomyopathy); patients who underwent cardiac surgery and patients with extracardiac disease with cardiac involvement such as autoimmune disorders. For this cohort of 26 adult patients (13 males; 13 females; mean age 63 ± 7 years) a prospective screening study for AFD was performed. After clinical evaluation, transthoracic echocardiography (analyzing signs of left ventricular hypertrophy) and pacemaker check, a dried blood spot sampled in filter paper was analyzed. This filter paper assay was performed in male patients in order to evaluate the α-Galactosidase A enzyme activity through the detection of Fabry disease biomarkers; only in the case of abnormal values, genetic investigation was performed. In female patients, the analysis was exclusively genetic. Results The analyses revealed 58% (15/26) of patients affected by mild LVH (IVS diameter ranging from 11 to 15 mm). No patient had severe LVH (IVS diameter ≥15 mm) or moderate-severe renal dysfunction (more than stage 3B, GFR below than 30-44 mL/min). In the restrict cohort considered, we found one 69 yo female patient with heterozygosis GLA pathogenic mutation, NM_000169.2:c.638A>C p.(Lys213Thr). She had normal value of liso-Gb3 1,1 ng/ml (n.v. ≤ 1,8 ng/ml). She had mild LVH (IVS diameter 12 mm) and no renal dysfunction. Familiar screening was programmed. Conclusion In a highly selected sample of relatively young patients with conduction disturbances requiring pacemaker implantation, a female patient with genetic mutation causing AFD has been identified. Therefore, it seems that screening efforts should be increased in this patient population. 1 Hemelsoet D, De Keyser J, Van Heuverswyn F et al. Screening for Fabry Disease in Male Patients With Arrhythmia Requiring a Pacemaker or an Implantable Cardioverter-Defibrillator. Circulation. 2021 Feb 23;143(8):872-874. doi: 10.1161/CIRCULATIONAHA.120.051400.

571 SUCCESSFUL PERMANENT PACEMAKER IMPLANTATION IN A PATIENT WITH DEXTROCARDIA AND SITUS INVERSUS TOTALIS: LOOKING AT THE MIRROR.

Abstract Background Dextrocardia is a rare congenital condition with a prevalence of 0.83 per 10000 pregnancies. Its most common configuration is situs inversus totalis, also known as “mirror-image dextrocardia”. This case report presents a clinical case of symptomatic sinus node dysfunction requiring permanent pacemaker implantation (PPI) in a patient with mirror-image dextrocardia. Case summary A 81-year-old female patient with known situs inversus totalis presented with recurrent syncope. Sick sinus syndrome was diagnosed after documentation of critical pauses (>6.3”) at 24-hour Holter monitoring, giving indication to elective PPI. At admission, 12-lead ECG showed sinus bradycardia and right axis deviation on the frontal plane (standard peripheral leads position and precordial leads on the right side of the chest). Transthoracic echocardiography was performed prior to the procedure with the ultrasound probe flipped and placed on the patient's right side of the thorax, thus achieving standard echocardiography windows and images. A preserved biventricular systolic function and the absence of relevant valvular disease or cardiac malformations was documented. The next day, a dual-chamber pacemaker was implanted following standard technique with the operator standing on the right side of the patient and with right subclavian vein puncture; the pacemaker pocket was created in the right pectoral region. The entire procedure was performed under fluoroscopic guidance using horizontally 180° flipped views, therefore obtaining identical images to those of standard PPI procedures, helping the operator identify anatomical structures during lead positioning. [Fig. 1 a - b] Chest X-ray confirmed correct pacemaker lead placement and absence of procedure-related complications. Stable and satisfactory lead parameters were observed at follow-up. Discussion In literature there are only a few case reports on PPI in situs inversus totalis. The symmetrical disposition of the anatomy makes transvenous PPI technically demanding. In this case the challenge was overcome by using flipped fluoroscopy images, to facilitate lead positioning maneuvres. This technique can be considered only in situs inversus totalis and not in other forms of dextrocardia, such as dextroversion and destroposition, because it is the only situation in which the anatomy is the mirror image of the normal one.

Single-center experience of temporary-permanent pacemaker use in COVID-19 patients supported with veno-venous ECMO: A case series.

In the first year of the COVID-19 pandemic, nine out of 129 patients (7%) developed life-threatening bradycardia episodes ultimately requiring a TPPM, whilst being supported with VV-ECMO for severe COVID-19 ARDS in our tertiary cardio-pulmonary failure center. All subjects had asystole due to sinus node dysfunction and experienced at least one episode involving cardiopulmonary resuscitation. Most bradycardic events were seen in the context of vagal hypersensitivity. Mean time from general ICU admission to TPPM insertion was 20.6 ± 8.9days. One patient developed a large chest wall hematoma weeks after TPPM implantation, no other TPPM-related issues were observed. No patient required a long-term pacing system. Six-months survival rate was high (89%). These findings suggested that transient life-threatening sinus node disease is not uncommon in ECMO-dependent COVID-19 ARDS patients. TPPM with an active fixation lead is sometimes needed to facilitate ongoing ICU care, however, long-term permanent pacing was not required.

Screening of Fabry disease in patients with an implanted permanent pacemaker

BackgroundAnderson-Fabry disease (AFD) is an X-linked inherited lysosomal disease caused by a defect in the gene encoding lysosomal enzyme α-galactosidase A (GLA). Atrio-ventricular (AV) nodal conduction defects and sinus node dysfunction are common complications of the disease. It is not fully elucidated how frequently AFD is responsible for acquired AV block or sinus node dysfunction and if some AFD patients could manifest primarily with spontaneous bradycardia in general population. The purpose of study was to evaluate the prevalence of AFD in male patients with implanted permanent pacemaker (PM). MethodsThe prospective multicentric screening in consecutive male patients between 35 and 65 years with implanted PM for acquired third- or second- degree type 2 AV block or symptomatic second- degree type 1 AV block or sinus node dysfunction was performed. ResultsA total of 484 patients (mean age 54 ± 12 years at time of PM implantation) were enrolled to the screening in 12 local sites in Czech Republic. Out of all patients, negative result was found in 481 (99%) subjects. In 3 cases, a GLA variant was found, classified as benign: p.Asp313Tyr, p.D313Y). Pathogenic GLA variants (classical or non-classical form) or variants of unclear significance were not detected. ConclusionThe prevalence of pathogenic variants causing AFD in a general population sample with implanted permanent PM for AV conduction defects or sinus node dysfunction seems to be low. Our findings do not advocate a routine screening for AFD in all adult males with clinically significant bradycardia.

Sustained ventricular arrhythmia and sinus node dysfunction revealing a cardiac amyloidosis: A case report

Amyloidosis is an infiltrative multisystem disease due to extracellular deposition of fibrils in tissues and organs. Cardiac involvement can result in progressive heart failure, conduction abnormalities and arrhythmias and is associated with a poor prognosis. Atrial arrhythmias and non-sustained ventricular arrhythmias are the most common arrhythmias in cardiac amyloidosis. However, the association of sinus node dysfunction and sustained ventricular arrhythmia is quite exceptional. A 59-year-old male patient was admitted with a gradually worsening dyspnea with a lipothymic discomfort. Upon emergency department, an initial electrocardiogram revealed a severe bradycardia related to a sinus node dysfunction. A transthoracic echocardiography and cardiac magnetic resonance imaging showed features suspicious for cardiac amyloidosis. The diagnosis of AL cardiac amyloidosis with multiple myeloma was confirmed based on histological evidence. During hospitalization, the patient presented a sustained unstable ventricular tachycardia which has been converted by electrical cardioversion. He was treated with an implantable cardioverter-defibrillator (ICD) for secondary prevention with one episode of appropriate therapy. Unfortunately, the patient died few weeks later. The AL subtype of cardiac amyloidosis is associated with higher rates of arrhythmias, especially VT. The management of arrhythmias in cardiac amyloidosis is complex and remains challenging given the lack of evidence. ICD was not associated with longer survival; these findings underscore the importance of careful patient selection for ICD. As prognosis improves with the advances made in the medical treatment of cardiac amyloidosis, further studies are required to guide the management of all types of arrhythmias in cardiac amyloidosis.

Extracellular matrix remodelling in ageing-related sinus node dysfunction

Extracellular matrix remodelling in ageing-related sinus node dysfunction

Sick Sinus Syndrome in a Female Patient with Chagas Disease. Case Report

Chagas disease is a zoonosis transmitted by Trypanosoma Cruzi, which has become a public health problem worldwide. The infection can be acute, chronic phases and reactivations, characterized by heart involvement. We report the case of a 33-year-old woman with stabbing chest pain, as well as hemiparesis in the left arm managed for 8 weeks, with persistent chest pain, electrocardiogram (ECG) showing a heart rate of 40 bpm. She is referred to a cardiologist who requests a Holter which shows pauses of 5.4 seconds and a transthoracic echocardiogram with LVEF 56%, PASP 24 mmHg; anti trypanosoma cruzi IgG antibodies were requested with a positive result, starting management based on nifurtimox; candidate patient for management with a double-chamber pacemaker, with remission of symptoms. In recent years, our knowledge about Chagas disease has expanded, electrocardiography is the most useful individual examination technique for these patients. Late manifestations include sinus node dysfunction leading to severe bradycardia, high-grade AV block, etc. Chagas disease should be suspected in all patients with an epidemiological history compatible with symptoms of cardiac involvement. and we believe that active intervention in endemic areas of the disease is especially relevant.

Adenylyl cyclase isoform 1 contributes to sinoatrial node automaticity via functional microdomains.

Sinoatrial node (SAN) cells are the heart's primary pacemaker. Their activity is tightly regulated by β-adrenergic receptor (β-AR) signaling. Adenylyl cyclase (AC) is a key enzyme in the β-AR pathway that catalyzes the production of cAMP. There are current gaps in our knowledge regarding the dominant AC isoforms and the specific roles of Ca2+-activated ACs in the SAN. The current study tests the hypothesis that distinct AC isoforms are preferentially expressed in the SAN and compartmentalize within microdomains to orchestrate heart rate regulation during β-AR signaling. In contrast to atrial and ventricular myocytes, SAN cells express a diverse repertoire of ACs, with ACI as the predominant Ca2+-activated isoform. Although ACI-KO (ACI-/-) mice exhibit normal cardiac systolic or diastolic function, they experience SAN dysfunction. Similarly, SAN-specific CRISPR/Cas9-mediated gene silencing of ACI results in sinus node dysfunction. Mechanistically, hyperpolarization-activated cyclic nucleotide-gated 4 (HCN4) channels form functional microdomains almost exclusively with ACI, while ryanodine receptor and L-type Ca2+ channels likely compartmentalize with ACI and other AC isoforms. In contrast, there were no significant differences in T-type Ca2+ and Na+ currents at baseline or after β-AR stimulation between WT and ACI-/- SAN cells. Due to its central characteristic feature as a Ca2+-activated isoform, ACI plays a unique role in sustaining the rise of local cAMP and heart rates during β-AR stimulation. The findings provide insights into the critical roles of the Ca2+-activated isoform of AC in sustaining SAN automaticity that is distinct from contractile cardiomyocytes.

Surgical Outcomes of Three Repair Techniques for Partial Anomalous Pulmonary Venous Connection in Adult Patients

Objectives: To investigate primary and secondary surgical outcomes following transcaval repair (TCR), modified Warden repair, and transatrial repair techniques for partial anomalous pulmonary venous connections (PAPVCs) and sinus venosus atrial septal defects (ASDs). Methods: This is an observational cohort clinical study. Patients who underwent TCR, modified Warden repair, and transatrial surgical repair for PAPVC and ASD between January 2003 and October 2019 at our institution were included in the study. Patients had one of the surgical procedures based on the anatomy of the defect. Results: Ten patients, seven (70%) males and three (30%) females, were included in the analysis. Seven patients underwent TCR, two patients the modified Warden technique, and one patient underwent transatrial surgical repair. Mean age was 57 years ± 14.7. Mean EuroScore II was 3.4 ± 3.5. The baseline left ventricle ejection fraction was 45 ± 6.5%. No patient had previous stroke, pacemaker (PM) implantation, or myocardial infarction. Total cardiopulmonary bypass and cross-clamping time were 123 ± 72.5 and 100 ± 48.5 min, respectively. Mean mechanical ventilation, mean intensive care unit, and mean hospital length of stay for the transcaval, modified Warden, and transatrial groups were 4.6 ± 10.7, 5.7 ± 8.8, and 10.5 ± 9.2 days, respectively. Superior caval or pulmonary venous obstruction, sinus node dysfunction, and PM implantation were not present at follow-up. The patient who underwent transatrial repair had died at 5.5-year follow-up due to myocardial infarction. Total survival rate at 6 years was 90%. Conclusions: The findings from this study elicit that all three techniques have low postoperative morbidity and are feasible and reliable procedures.

Whole Exome Sequencing Identifies a Heterozygous Variant in the Cav1.3 Gene CACNA1D Associated with Familial Sinus Node Dysfunction and Focal Idiopathic Epilepsy.

Cav1.3 voltage-gated L-type calcium channels (LTCCs) are involved in cardiac pacemaking, hearing and hormone secretion, but are also expressed postsynaptically in neurons. So far, homozygous loss of function mutations in CACNA1D encoding the Cav1.3 α1-subunit are described in congenital sinus node dysfunction and deafness. In addition, germline mutations in CACNA1D have been linked to neurodevelopmental syndromes including epileptic seizures, autism, intellectual disability and primary hyperaldosteronism. Here, a three-generation family with a syndromal phenotype of sinus node dysfunction, idiopathic epilepsy and attention deficit hyperactivity disorder (ADHD) is investigated. Whole genome sequencing and functional heterologous expression studies were used to identify the disease-causing mechanisms in this novel syndromal disorder. We identified a heterozygous non-synonymous variant (p.Arg930His) in the CACNA1D gene that cosegregated with the combined clinical phenotype in an autosomal dominant manner. Functional heterologous expression studies showed that the CACNA1D variant induces isoform-specific alterations of Cav1.3 channel gating: a gain of ion channel function was observed in the brain-specific short CACNA1D isoform (Cav1.3S), whereas a loss of ion channel function was seen in the long (Cav1.3L) isoform. The combined gain-of-function (GOF) and loss-of-function (LOF) induced by the R930H variant are likely to be associated with the rare combined clinical and syndromal phenotypes in the family. The GOF in the Cav1.3S variant with high neuronal expression is likely to result in epilepsy, whereas the LOF in the long Cav1.3L variant results in sinus node dysfunction.

Trends in research on sick sinus syndrome: A bibliometric analysis from 2000 to 2022

Sick sinus syndrome (SSS) is a refractory arrhythmia disease caused by the pathological changes of sinoatrial node and its adjacent tissues. 2,251 publications related to SSS were retrieved from Web of Science database from 2000 to 2022 and analyzed by using VOS viewer and CiteSpace software. The results showed the United States dominated the field, followed by Japan, Germany, and China. SSS was closely related to risk factors such as atrial fibrillation and aging. Sick sinus syndrome, atrial fibrillation and sinus node dysfunction were the top three keywords that had the strongest correlation with the study. Pacemaker implantation, differentiation and mutation are research hotspots currently. Clinical studies on SSS found that sick sinus syndrome, atrial fibrillation, and pacemakers were the top three keywords that had the largest nodes and the highest frequency. In the field of basic applied research and basic research, atrial fibrillation and pacemaker cells were the focus of research. In conclusion, bibliometric analysis provided valuable information for the prevention, treatment and future research trends of SSS.

Abstract 14557: Prognostic Role of Pathogenic Mutations in Brugada Syndrome: Results From Wide Gene Testing

Introduction: A pathogenic/likely pathogenic (P/LP) mutation can be found in 20-25% of patients with Brugada syndrome (BrS) and a P/LP mutation in SCN5A is associated with a worse prognosis. However, the prognosis of non SCN5A genes mutations is unclear. Methods: All BrS patients, were prospectively enrolled in the UZB registry between 1992 and 2022. Inclusion criteria for this study were: 1) BrS diagnosis; 2) Genetic analysis performed with a wide gene panel; 3) Classification of variants following ACMG guidelines. Patients with a P/LP variant in SCN5A were defined as (P+/SCN5A+); patients with a P/LP variant in a gene different from SCN5A were defined as (P+/SCN5A-). All other patients were classified as (P-). Results: A total of 452 BrS patients were analyzed. Any P/LP mutation was found in 108 (23.9%) patients, 94 (20.8%) patients P+/SCN5A+ and 14 (3.1%) patients P+/SCN5A-. Compared with P- patients, P+ patients were younger, more frequently had a spontaneous BrS type I ECG, sinus node dysfunction, aborted sudden cardiac death history and longer PQ interval, Table 1. After a mean follow-up of 116.7 months, 47 patients (10.4%) experienced a ventricular arrhythmia (VA). At survival analysis, P- patients had higher VA free survival, compared with P+/SCN5A+ (93% vs 81.9%, p=0.023) and with P+/SCN5A- (93% vs 57.1%, p<0.001). Among P+ patients, P+/SCN5A+ patients had higher VA free survival compared with P+/SCN5A- (81.9% vs 57.1%, p=0.023), Figure 2. At Cox multivariate analysis, P+ was an independent predictor of VA occurrence (HR= 2.23, CI 95% 1.10-4.58, p=0.027). Conclusions: In a large BrS cohort, the diagnostic yield for P/LP mutations is 23.9%. P+ is an independent predictor of VA.

Abstract 11024: 3D Localization of Left Bundle Branch Area and Pacing Lead Orientation During Left Bundle Pacing

Introduction: Left bundle branch area (LBBA) pacing is a novel physiologic pacing technique where the pacing lead is inserted through the right ventricular (RV) septum to capture the LBBA. Among the challenges encountered are identifying the RV septal site, assessing the plane of the lead, determining the depth of insertion, and repositioning the lead to a new site if needed. Navik 3D is a unique localization system that can convert 2D fluoroscopy images into 3D. Methods: Following consent, we studied six consecutive patients with a mean age of 72 years who underwent LBBA pacing. Patient characteristics including female sex (n=2), mean body mass index (33.8 kg/m 2 ), mean left ventricle ejection fraction (51%), mean intraventricular diastolic thickness (1.06 cm), and presence of hypertension (n=4), diabetes (n=4) atrial fibrillation (n=4), and left bundle branch block (n=1). Patients presented with either complete heart block (n=4) or sinus node dysfunction (n=2). LBBA was localized on the RV septum using fluoroscopy and contrast injection. The RV septum, RV apex, lead position, and His locations were identified in 3D using 2D fluoroscopy from two different views. Then, 3D locations were projected on the 2D fluoroscopy image via the Navik 3D mapping system. The system could also mark an unsuccessful site and allow repositioning. Results: All patients had a successful placement in the LBBA with qR in V1, short mean left ventricular activation time (ms) in V6 (73.1), and left bundle potential was recorded in 3 patients. Conclusions: Localization of LBBA in 3D is feasible and may be useful for optimal lead placement.

Abstract 14826: Single Day Intravenous Sotalol as a Loading Dose to Initiate Oral Sotalol Therapy: Is it Safe and Efficacious?

Introduction: Due to pro-arrhythmic effects associated with Sotalol, inpatient initiation with QTc monitoring for five doses is recommended. An IV loading dose followed by two oral doses has been shown to achieve steady-state concentrations. Hypothesis: To evaluate the safety of single day loading of IV sotalol in patients with atrial fibrillation and atrial flutter (AF/AFL). Methods: We prospectively evaluated 40 patients at our institution who received IV sotalol as single day loading dose for initiation of oral sotalol therapy for AF/AFL. IV sotalol dose was calculated based on target oral dose as indicated by baseline QTc interval and renal function. Patients' QTc (in sinus) was measured via ECG on 15 minutes intervals and after IV loading completion. Loading was considered complete after second oral dose. All patients were monitored via a mobile cardiac outpatient monitor for 3 days followed by a final 12 ECG. Results: A total of 40 patients were included in the study. The mean age was 69 + 8.2 years, 78.9% of patients were men. QTc significantly increased from 435.9 + 26.4 to 462.9 + 31.6 with following IV loading (p<0.001), that stabilized following oral loading completion (450.63 + 44.4; p=0.12). There were no cases of severe bradycardia, sinus node dysfunction, ventricular arrhythmias. reported. Conclusions: Our study sheds evidence that rapid IV sotalol loading in AF/AFL is safe and efficacious. This will not only provide patient convenience but will lead to reduced economic burden on patients and health care systems.

Abstract 10897: Severe Atrial Dysfunction and Sick Sinus Syndrome in a Patient With Scn5a Mutation

Introduction: SCN5A mutations are associated with numerous cardiovascular conditions, including dilated cardiomyopathy, atrial fibrillation, and sick sinus syndrome. Specific variants in patients with severe atrial dysfunction may be associated with increased risk of stroke even in young patients. Case: This case describes a previously healthy 38-year-old male of French descent who presented with intermittent palpitations and presyncope associated with atrial flutter followed by prolonged conversion pauses up to 7.5 seconds, then followed by junctional bradycardia. Echocardiogram showed a mildly dilated left atrium. Electrophysiology study demonstrated extensive scarring in the left atrium with normal sinus node function and right atrial voltage. No atrial fibrillation was noted. He was also found to have typical atrial flutter and mitral flutter. He underwent cavotricuspid isthmus ablation and mitral annular flutter ablation. Due to his vagal-mediated pauses and junctional rhythm, he also underwent cardioneuroablation aimed at partial denervation. Following this, he had further episodes of junctional rhythm on the days after exercise. He underwent further total cardioneuroablation and was found to have progressive scarring at the sinus node area and sinus node dysfunction, so a permanent pacemaker was placed. He underwent genetic testing which demonstrated SCN5A heterozygous missense pathogenic variant c.2823G>A. Conclusion: The SCN5a gene encodes the alpha subunit of the cardiac sodium channel, which is responsible for initiation and propagation of action potentials. SCN5A variants are associated with a number of cardiovascular conditions. There are reports of stroke in young French patients with severe atrial dysfunction and SCN5A mutations, including variant c.2823G>A, demonstrating that severe atrial dysfunction is a risk factor for stroke regardless of CHADS2VASc score, and specific SCN5A mutations may be associated with increased risk of stroke. Given these reports and absence of relevant guidelines, apixaban was continued indefinitely for prevention of stroke. At follow-up two months later, the patient resumed physical activity and reported symptomatic improvement, without any episodes of syncope or near syncope.

Abstract 9801: Late Onset Phrenic Nerve Injury Post PPM Placement

Background: Transient phrenic nerve paralysis is a known immediate complication of cardiac implantable electronic device implants. Proposed mechanisms include direct nerve injury during venipuncture, nerve compression from a mediastinal hematoma, or local anesthetic instillation. However, the authors present a rare case of phrenic nerve injury as a late complication of permanent pacemaker (PPM) placement after excluding other etiologies. Case Summary: A 39 year-old female with a history of hypertension and diabetes underwent dual-chamber permanent pacemaker (PPM) placement due to sinus node dysfunction. She presented a year later with a subacute onset of progressive dyspnea on exertion that worsened over the four days prior to admission. Dyspnea was associated with right neck and shoulder pain. Chest radiography at presentation showed elevated right hemidiaphragm. A fluoroscopic sniff test confirmed right hemidiaphragm paralysis. Chest computed tomography revealed no anatomic abnormalities. Magnetic resonance imaging of the cervical spine showed no spinal cord or nerve root lesions. Electromyography confirmed right phrenic nerve injury as the etiology of elevated right hemidiaphragm. She continued to experience exertional dyspnea and orthopnea. Thoracic surgery scheduled the patient for insertion of a diaphragmatic pacemaker. She was discharged pending her surgery. Discussion: Late onset diaphragmatic paralysis due to phrenic nerve injury is a rare complication of PPM insertion. The mechanism of phrenic nerve injury from PPM insertion is unclear. It may result from direct or indirect phrenic nerve micro-injury by the relatively stiff pacemaker leads or peel-away introducers, resulting in slow Wallerian degeneration of the phrenic nerve fibers. In addition, microhematomas, undetected by chest computed tomography, inflammatory or thrombotic changes of the subclavian vein or the superior vena cava may influence the adjacent phrenic nerve.

Abstract 15513: Angiovac as an Alternative to Surgical Excision of a Large Infective Endocarditis Vegetation

Background: Angiovac device is a suction cannula inserted percutaneously or surgically connected to extracorporeal circuit approved for removal of fresh soft thrombi/emboli. Cardiac surgery is indicated in Infective Endocarditis (IE) when the vegetation is >10 mm. Angiovac is used for IE in nonsurgical candidates. Here, we present 2 cases of successful use of Angiovac in treating large IE vegetation. Presentation: (1) A 70-year-old male with HFrEF and inducible VF on electrophysiological study requiring ICD implantation admitted for sepsis with Corynebacterium stratum bacteremia. TTE revealed mobile echo-density, 24 X 14 mm attached to the RV ICD lead. (2) 67-year-old female with sinus node dysfunction requiring permanent pacemaker who presented with constitutional symptoms. Blood culture grew coagulase-negative Staphylococcus. TEE revealed echodense coating around the RV lead, 15 mm in thickness. Management: Patient 1 was deemed nonsurgical candidate by cardiothoracic surgery. Instead, Angiovac was performed. Intraoperative TEE revealed a 30x20mm right atrial ICD lead vegetation. Angiovac catheter was advanced under TEE guidance to the right atrium. Once the catheter was abutting the infected thrombus multiple aspiration harvesting embolic material as in the picture. A postprocedural TTE demonstrated the absence of the RA echodensity. A subsequent laser lead extraction was performed. Patient 2 was given IV vancomycin. Angiovac procedure was successfully performed with subsequent laser lead extraction planning. Conclusion: AngioVac is a minimally invasive and effective procedure in the management of large vegetations in nonsurgical candidate patients.

Abstract 13637: Advanced Multimodality Imaging of Atrial Baffle Leak After the Senning Operation

Description of Clinical Presentation We present a 40-year-old male with dextro-transposition of the great vessels and history of a Senning repair as an infant and a transvenous dual-chamber pacemaker at 7 years of age for sinus node dysfunction. Advanced imaging, including cardiac computed tomography (CT) and cardiac magnetic resonance (CMR), were performed as routine testing to evaluate the baffle and ventricular function. Diagnostic Testing and Their Most Important Findings: An ECG-gated cardiac CT demonstrated multiple defects between the systemic and pulmonary venous baffle (1A). CMR demonstrated a severely dilated right ventricle with moderately depressed systolic function, mild tricuspid valve insufficiency, and a moderately dilated, hyperdynamic left ventricle (LV). Advanced 4D flow confirmed a pulmonary to systemic blood flow ratio of 2.8:1, with large left-to-right shunt corresponding to the defects noted on CT (1B). There was no evidence of systemic or pulmonary venous baffle obstruction. 3D transesophageal echocardiography (echo) demonstrated multiple deficiencies in the septal/posterior atrial flap (1C). A stenotic, bicommissural pulmonary valve with moderate flow acceleration was also noted. 3D modelling from the CT/CMR data further clarified the location of the baffle leaks relative to pacemaker leads (1D). Cardiac catheterization confirmed these findings of large left-to-right shunt. Learning Points from this case: Atrial switch patients have a significant risk for baffle leaks, which can be challenging to identify. Advanced imaging including CT, CMR, 3D modeling, 3D echo, and cardiac catheterization are complimentary in the diagnosis of baffle leaks and can guide therapeutic options.