Perforation of the interventricular septum and left ventricular (LV) free wall by a right ventricular (RV) lead is an extremely rare and potentially life-threatening complication. In this case report, we discussed the diagnosis and management of a very unusual complication of pacemaker (PM) implantation, i.e., LV perforation brought on by an RV pacing lead.

The cardiac conduction system was examined histologically in 13 canine cases of atrioventricular (AV) valve endocardiosis with third-degree AV block. In all cases, gross examination revealed marked thickening and distortion of the base of the central fibrous body (CFB) and varying degrees of endocardial thickening of the upper portion of the ventricular septum (VS) as well as marked thickening of the mitral and tricuspid valve leaflets due to myxomatous degeneration. Microscopically, the thickened and distorted CFB had encased or trapped, either partly or totally, the underlying penetrating and branching portions of the AV bundle. The myxomatous and/or fibrofatty tissue, which had proliferated at the base of the extensive CFB, protruded into or encroached on the AV bundle, causing severe (51-75%) to very severe (76% or more) reduction of the conduction fibres. The upper portions of the left and right bundle branches were involved in the endocardial thickening due to degenerative and fibrotic changes at the uppermost VS; however, both bundle branches were much less severely affected than the AV bundle, the degree of reduction of the conduction fibres ranging from mild (25% or less) to moderate (26-50%). These observations suggest that the sites most vulnerable to lesions in the AV conduction system are the penetrating and branching portions of the AV bundle, which would represent the anatomical basis for third-degree AV block in canine cases of AV valve endocardiosis.

Supraventricular tachycardia (SVT) with ventriculoatrial (VA) block can represent a diagnostic challenge. We present a case of SVT where His-His interval shortening was repeatedly observed during episodes of VA block. This novel observation is more diagnostically suggestive of atrioventricular nodal re-entrant tachycardia, as opposed to orthodromic re-entry using a nodofascicular or nodoventricular pathway where a constant His-His is recorded during episodes of VA block. (Level of Difficulty: Intermediate.).

Salmonid ventricles are composed of spongy and compact myocardium, the latter being perfused via a coronary circulation. Rainbow trout (Oncorhynchus mykiss) acclimated to sea water have higher proportions of compact myocardium and display stroke volume-mediated elevations in resting cardiac output relative to freshwater-acclimated trout, likely to meet the higher metabolic needs of osmoregulatory functions. Here, we tested the hypothesis that cardiorespiratory performance of rainbow trout in sea water is more dependent on coronary perfusion by assessing the effects of coronary ligation on cardiorespiratory function in resting and exhaustively exercised trout acclimated to fresh water or sea water. While ligation only had minor effects on resting cardiorespiratory function across salinities, cardiac function after chasing to exhaustion was impaired, presumably due to atrioventricular block. The 33% and 17% lower maximum O2 consumption rate caused corresponding 41% and 17% impairments of aerobic scope in ligated fish acclimated to sea water and fresh water, respectively. However, this was only partly explained by effects on cardiac performance, as maximum stroke volume was only significantly impaired by ligation in sea water, resulting in 38% lower maximum cardiac output in seawater compared with 28% in fresh water. The more pronounced effect on respiratory performance in sea water was presumably also explained by lower blood O2 carrying capacity, with ligated seawater-acclimated trout having 16% and 17% lower haemoglobin concentration and haematocrit, relative to ligated freshwater trout. In conclusion, we show that the coronary circulation allows seawater-acclimated trout to maintain aerobic scope at a level comparable to fresh water.

Although not routinely used, cardioneuroablation or modulation of the cardiac autonomic nervous system has been proposed as an alternative approach to treat young individuals with enhanced vagal tone and significant atrioventricular (AV) disturbances.We report the case of a 42-year-old athlete with prolonged ventricular pauses associated with sinus bradycardia and paroxysmal episodes of AV block (maximum of 6.6 s) due to enhanced vagal tone who was admitted to our hospital for pacemaker implantation. Cardiac magnetic resonance and stress test were normal. Although he was asymptomatic, safety concerns regarding possible neurological damage and sudden cardiac death were raised, and he accordingly underwent electrophysiological study (EPS) and cardiac autonomic denervation. Mapping and ablation were anatomically guided and radiofrequency pulses were delivered at empirical sites of ganglionated plexi. Modulation of the parasympathetic system was confirmed through changes in heart rate and AV nodal conduction properties associated with a negative cardiac response to atropine administration.After a follow-up of nine months, follow-up 24-hour Holter revealed an increase in mean heart rate and no AV disturbances, with rare non-significant ventricular pauses, suggesting that this technique may become a safe and efficient procedure in this group of patients.

Methemoglobinemia is a rare, life-threatening condition that occurs when the body is exposed to oxidative stress. We present the case of a 72-year-old female with a past medical history of hypertension, obesity, dyslipidemia, and heart failure who was admitted to the emergency department with altered mental status and respiratory failure. After admission, we also identified an atrioventricular block 2:1, anemia, and skin discoloration. We performed endotracheal intubation and started mechanical ventilation due to respiratory failure; however, the patient retained an oxygen "saturation gap" despite adequate ventilation. In the initial laboratory evaluation, methemoglobinemia was found to be 13%, reaching a maximum level of 16%. An electroencephalogram revealed status epilepticus after her admission to the intensive care unit. Despite all efforts and supportive care, methylene blue therapy was never attempted, and the patient died. Our case emphasizes the importance of a high index of suspicion for methemoglobinemia, especially in the presence of an oxygen "saturation gap," and that despite relatively low levels of methemoglobinemia, it can have a more severe clinical presentation in patients with comorbidities. In these patients, a reduced threshold for administering methylene blue should be taken into account.

The association between type 2 diabetes (T2D) and the development of cardiac arrhythmias and conduction disturbances has not been extensively studied. Arrhythmia was defined as atrial fibrillation and flutter (AF/AFl), ventricular tachycardia (VT) and ventricular fibrillation (VF), and conduction abnormality as sinus node disease (SND), atrioventricular (AV) block or pacemaker implantation, and intraventricular conduction blocks (IVCB). Incidence rates and Cox regression were used to compare outcomes, and to assess optimal levels for cardiometabolic risk factors and risk associated with multifactorial risk factor control (i.e., HbA1c, LDL-C, systolic blood pressure (SBP), BMI and eGFR), between patients with versus without T2D. The analyses included data from 617,000 patients with T2D and 2,303,391 matched controls. Patients with diabetes and the general population demonstrated a gradual increase in rates for cardiac conduction abnormalities and virtually all age-groups for AF/AFI showed increased incidence during follow-up. For patients with versus without T2D, risks for cardiac arrhythmias were higher, including for AF/AFl (HR 1.17, 95% CI 1.16-1.18), the composite of SND, AV-block or pacemaker implantation (HR 1.40, 95% CI 1.37-1.43), IVCB (HR 1.23, 95% CI 1.18-1.28) and VT/VF (HR 1.08, 95% CI 1.04-1.13). For patients with T2D who had selected cardiometabolic risk factors within target ranges, compared with controls, risk of arrythmia and conduction abnormalities for T2D vs not were: AF/AFl (HR 1.09, 95% CI 1.05-1.14), the composite of SND, AV-block or pacemaker implantation (HR 1.06, 95% CI 0.94-1.18), IVCB (HR 0.80, 95% CI 0.60-0.98), and for VT/VF (HR 0.97, 95% CI 0.80-1.17). Cox models showed a linear risk increase for SBP and BMI, while eGFR showed a U-shaped association. Individuals with T2D had a higher risk of arrhythmias and conduction abnormalities than controls, but excess risk associated with T2D was virtually not evident among patients with T2D with all risk factors within target range. BMI, SBP and eGFR displayed significant associations with outcomes among patients with T2D.

We present the use of CineECG in visualizing abnormal ventricular activation in a case of a complex conduction disorder. CineECG combines the standard 12‑lead surface ECG with a 3D anatomical model of the heart. It projects the location and direction of the average ventricular activation and recovery on the heart model over time. In this case, CineECG was able to visualize the different type of fascicular conduction in this progressive conduction block. This novel imaging technique was able to provide additional insight in this complex case, and might be of use in other complex ECG patterns.

Background. Data on leadless pacemaker (LPM) implantation in an emergency setting are currently lacking. Objective. We aimed to investigate the feasibility of LPM implantation for emergency bradyarrhythmia, in patients referred for urgent PM implantation, in a large, multicenter, real-world cohort of LPM recipients. Methods. Two cohorts of LPM patients, stratified according to the LPM implantation scenario (patients admitted from the emergency department (ED+) vs. elective patients (ED-)) were retrieved from the iLEAPER registry. The primary outcome of the study was a comparison of the peri-procedural complications between the groups. The rates of peri-procedural characteristics (overall procedural and fluoroscopic duration) were deemed secondary outcomes. Results. A total of 1154 patients were enrolled in this project, with patients implanted due to an urgent bradyarrhythmia (ED+) representing 6.2% of the entire cohort. Slow atrial fibrillation and complete + advanced atrioventricular blocks were more frequent in the ED+ cohort (76.3% for ED+ vs. 49.7% for ED-, p = 0.025; 37.5% vs. 27.3%, p = 0.027, respectively). The overall procedural times were longer in the ED+ cohort (60 (45-80) mins vs. 50 (40-65) mins, p < 0.001), showing higher rates of temporary pacing (94.4% for ED+ vs. 28.9% for ED-, p < 0.001). Emergency LPM implantation was not correlated with an increase in the rate of major complications compared to the control group (6.9% ED+ vs. 4.2% ED-, p = 0.244). Conclusion. LPM implantation is a feasible procedure for the treatment of severe bradyarrhythmia in an urgent setting. Urgent LPM implantation was not correlated with an increase in the rate of major complications compared to the control group, but it was associated with longer procedural times.

Atrial premature contractions (PACs) that block at the atrial ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing. This article is protected by copyright. All rights reserved.

Severe hypertension has numerous etiologies. When accompanied by bradycardia, the spectrum of differential diagnoses is greatly narrowed and is commonly seen in patients with increased intracranial pressure. However, other etiologies such as bradycardia-induced hypertension are rarely mentioned. Here we report the case of a 73-year-old woman presenting with symptoms of heart failure, severe hypertension, and bradycardia with a 2:1 atrioventricular block. Echocardiography demonstrated increased left ventricular filling secondary to bradycardia and prolonged diastole, leading to greater ventricular stretch, increased contractile force and greater stroke volume (Frank-Starling mechanism), which subsequently caused elevated systolic blood pressure (BP), low diastolic BP and a wide pulse pressure. Treating the bradycardia by pacing led to an immediate and substantial BP reduction, although complete BP normalization had a slower time course and was probably due to the concomitant effect of the antihypertensive treatment initiation. This pathophysiological mechanism has received little attention in the literature. Further, stimulation of sympathetic afferents located in the heart by distension of the cardiac walls as well as the role of vagally innervated cardiopulmonary receptors due to the increased pressure in the heart and the pulmonary artery should also be kept in mind as alternative hypotheses.

Objective: To review the clinical data of 7 patients with Danon disease and analyze their clinical characteristics. Methods: The medical records of 7 patients with Danon disease, who were hospitalized in Peking Union Medical College Hospital of Chinese Academy of Medical Sciences from April 2008 to July 2021, were reviewed and summarized, of which 6 cases were diagnosed as Danon disease by lysosomal-associated membrane protein-2 (LAMP-2) gene mutation detection and 1 case was diagnosed by clinicopathological features. Clinical manifestations, biochemical indexes, electrocardiogram, echocardiography, skeletal muscle and myocardial biopsy and gene detection results were analyzed, and patients received clinical follow-up after discharge. Results: Six patients were male and average age was (15.4±3.5) years and the average follow-up time was (27.7±17.0) months. The main clinical manifestations were myocardial hypertrophy (6/7), decreased myodynamia (2/7) and poor academic performance (3/7). Electrocardiogram features included pre-excitation syndrome (6/7) and left ventricular hypertrophy (7/7). Echocardiography examination evidenced myocardial hypertrophy (6/7), and left ventricular dilatation and systolic dysfunction during the disease course (1/7). The results of skeletal muscle biopsy in 6 patients were consistent with autophagy vacuolar myopathy. Subendocardial myocardial biopsy was performed in 3 patients, and a large amount of glycogen deposition with autophagosome formation was found in cardiomyocytes. LAMP-2 gene was detected in 6 patients, and missense mutations were found in all these patients. During the follow-up period, implantable cardioverter defibrillator implantation was performed in 1 patient because of high atrioventricular block 4 years after diagnosis, and there was no death or hospitalization for cardiovascular events in the other patients. Conclusion: The main clinical manifestations of Danon disease are cardiomyopathy, myopathy and mental retardation. Pre-excitation syndrome is a common electrocardiographic manifestation. Autophagy vacuoles can be seen in skeletal muscle and myocardial pathological biopsies. LAMP-2 gene mutation analysis is helpful in the diagnose of this disease.

This report describes a 69-year-old man with eosinophilia that was detected during a medical check-up. A review of his medical history revealed that his absolute eosinophil count was 990/µl at the age of 55 and increased to 5,380/µl at the age of 69. Electrocardiogram revealed first-degree atrioventricular block at the age of 58, followed by ST-segment depression and a negative T wave at the age of 65. The echocardiogram was normal at the age of 65. We diagnosed him with FIP1L1::PDGFRA-positive chronic eosinophilic leukemia by detecting the FIP1L1::PDGFRA fusion gene by fluorescence in situ hybridization. He had no symptoms at the first visit; however, echocardiography and contrast-enhanced computed tomography revealed an abnormal structure, considered a thrombus, within the left ventricular apex and apex wall thickening. We initiated imatinib (100 mg/day), and the eosinophilia disappeared in a month. However, his cardiac impairment worsened, and he gradually developed symptoms of heart failure. This case is valuable because it shows the long-term course of the disease, with 15 years of laboratory findings until diagnosis. Our findings suggest that in cases of eosinophilia with an abnormal electrocardiogram, contrast-enhanced cardiac magnetic resonance imaging should be considered earlier.

Objectives: To examine the short-term and mid-term effects of surgical treatment of obstructive hypertrophic cardiomyopathy (HCM) in one center. Methods: The perioperative data and short-term follow-up outcomes of 421 patients with obstructive HCM who received surgical treatment at Department of Cardiac Surgery, Zhongshan Hospital, Fudan University from January 2017 to December 2021 were analyzed retrospectively. There were 207 males and 214 females, aged (56.5±11.7) years (range: 19 to 78 years). Preoperative New York Heart Association (NYHA) classification included 45 cases of class Ⅱ, 328 cases in class Ⅲ, and 48 cases in class Ⅳ. Fifty-eight patients were diagnosed with latent obstructive HCM and 257 patients had moderate or more mitral regurgitation with 56 patients suffering from intrinsic mitral valve diseases. All procedures were completed by a multidisciplinary team, including professional echocardiologists involving in preoperative planning for proper miitral valve management strategies and intraoperative monitoring. A total of 338 patients underwent septal myectomy alone, and 59 patients underwent mitral valve surgery along with myectomy. A single transaortic approach was used in 355 patients, and a right atrial-atrial septal/atrial sulcus approach was used in 51 other patients. Long-handled minimally invasive surgical instruments were wsed for the procedures. Student t test, Wilcoxon rank sum test, χ2 test or Fisher exact test were used to compare the data before and after surgery. Results: The aortic cross-clamping time of septal myectomy alone was (34.3±8.5) minutes (range: 21 to 94 minutes). Eighteen patients had intraoperative adverse events and underwent immediate reoperation, including residual obstruction (10 patients), left ventricular free wall rupture (4 patients), ventricular septal perforation (3 patients), and aortic valve perforation (1 patient). Four patients died during hospitalization, and 11 patients developed complete atrioventricular block requiring permanent pacemaker implantation. After discharge, 384 (92.1%) patients received a follow-up visit with a median duration of 9 months. All follow-up patients survived with significantly improved NYHA classifications: 216 patients in class Ⅰ and 168 patients in class Ⅱ (χ2=662.73, P<0.01 as compared to baseline). At 6 months after surgery, follow-up echocardiography showed that the thickness of the ventricular septum ((13.6±2.5) mm vs. (18.2±3.0) mm, t=23.51, P<0.01) and the peak left ventricular outflow tract gradient ((12.0±6.3) mmHg vs. (93.4±19.8) mmHg, 1 mmHg=0.133 kPa, t=78.29, P<0.01) were both significantly lower than baseline values. Conclusion: The construction of the surgical team (including echocardiography experts), proper mitral valve management strategies, identification and management of sub-mitral-valve abnormalities, and application of long-handled minimally invasive surgical instruments are important for the successful implementation of septal myectomy with satisfactory short-and medium-term outcomes.