Conduction Block Research Articles

Functional block in the initiation and maintenance of common flutter: detailed electrophysiological study and electro-anatomical mapping

IntroductionThe precise pathophysiology of common atrial flutter remains imperfectly known. The mechanisms of arrhythmia initiation and the role of areas of slow conducting myocardium and functional block are still debated topics.MethodsWe conducted a detailed electrophysiological study of a patient to illustrate and refine these concepts. Prior to CTI ablation, electrophysiological study and electro-anatomical mapping were performed, focusing on initiation and maintenance mechanisms of the arrhythmia.ResultsThe initiation of common atrial flutter takes place on the septal aspect of the cavo-tricuspid isthmus where functional unidirectional conduction block occurs. The direction of activation is therefore frequently counter-clockwise, and the arrhythmia stabilizes around the vena cavas and sinus venosus/crista terminalis region. No conduction slowing is present.ConclusionsCommon atrial flutter initiates when functional unidirectional conduction block occurs on the septal cavotricuspid isthmus. Its rotation is limited by anatomical and functional boundaries.

Abstract 4136863: Diffuse Functional and Structural Abnormalities in Fibrosis: Potential Structural Basis for Sustaining Atrial Fibrillation

Background: Structural remodeling is associated with atrial fibrillation (AF), but detailed structural and functional characteristics is not well defined. Goal: Using a novel transgenic goat model with cardiac-specific overexpression of TGF-β1 leading to increased cardiac fibrosis, we evaluated detailed structural and functional differences between fibrotic and healthy regions of the atria. Methods: Ex-vivo MRI and histology were used to evaluate fibrosis, fiber disarray, and structural anisotropy. Ex-vivo MRI intensity values were scaled to standard deviations around the mean. The functional analysis examined conduction speeds and direction heterogeneity. Conduction anisotropy was measured along the fiber direction obtained with diffusion tensor imaging. Results: The transgenic goats (n=12) had, on average, 21% of the left atria labeled as fibrotic determined from ex-vivo MRI. The histology samples taken from the labeled fibrotic regions had an increase in fibrosis percentage compared to labeled healthy regions (7.78±3.76% vs 2.80±1.86%, p<0.01). The structural anisotropy was lower in fibrotic regions (0.196±0.002 vs 0.244±0.002, p<0.01). Fiber disarray was greater in the fibrotic regions (20.3±0.2° vs 19.2±0.1°, p<0.01). The fibrotic regions had slower conduction speeds (0.78±0.02 m/s vs 1.12±0.02 m/s, p<0.01) and more aligned conduction directions (30.5±0.2° vs 31.6±0.1°, p<0.01), potentially developing unidirectional conduction block. Conduction anisotropy, measured on the fiber directions, was found to be lower in the fibrotic regions (1.86±0.05 vs 2.10±0.02, p=0.04). As scaled MRI intensity increased, the conduction speed, heterogeneity, and anisotropy all decreased. Conclusions: Functional and structural differences exist between fibrotic and healthy regions of the atria. Though statistically significant, the changes are not discrete. The correlation showed gradual functional abnormalities with MRI intensities. Fibrotic regions tended to have increased fiber disarray, slower conduction, and more unidirectional propagation with lower conduction and structural anisotropy. Diffuse functional and structural abnormalities may allow fibrotic regions to serve as a substrate to sustain AF.

Clinical Features of Conduction Block in Ulnar Neuropathy at the Elbow: The Surgery of the Ulnar Nerve (SUN) Multicenter Clinical Trial.

In ulnar neuropathy at the elbow, weakness is classically a sign of severe disease. Weakness is associated with motor axonal loss as measured by decreased distal compound muscle action potential (CMAP) amplitude. Conduction block, a demyelinating phenomenon that recovers readily, can also cause weakness, creating ambiguity for the treating clinician. This cross-sectional study evaluated baseline blinded data collected from 2020-2023 from the Surgery of the Ulnar Nerve randomized controlled trial comparing in-situ decompression versus transposition procedures. Adult patients underwent electrodiagnostic testing, clinical motor and sensory testing, and completed the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire. 177 patients were categorized into 3 distinct groups based on normal distal CMAP amplitudes (77 patients), presence of conduction block with or without distal CMAP amplitude loss (37 patients), or pure axonal loss with distal CMAP amplitude loss in the absence of conduction block (63 patients). Compared to the normal group, patients with conduction block had significantly decreased pinch strength and worse function domain scores on the Michigan Hand Questionnaire and Carpal Tunnel Questionnaire, but shorter duration of disease. Patients with pure axonal loss had decreased pinch strength, worse 2-point discrimination, and worse overall, function and aesthetics domain scores on the Michigan Hand Questionnaire. There was a significant interaction between the effects of conduction block and distal CMAP amplitude on pinch strength, indicating that higher degrees of conduction block resulted in more pronounced loss of pinch strength in patients with relatively preserved distal CMAP amplitude. Our findings support the paradigm that ulnar neuropathy at the elbow presenting with conduction block represents a distinct and intermediate pathophysiology, distinguished by quicker onset with less advanced neurological deficits. Prognostic Level II.

SIMULATION OF GEOELECTRIC STRUCTURE OF NORTHERN VIETNAM BY 3D INVERSION OF MAGNETOVARIATIONAL TIPPERS

This paper presents the results of constructing a model of the geoelectric structure of Northern Vietnam obtained by 3D inversion of magnetovariational tippers calculated for 13 values of variation periods in a range of 40–10047 s at 12 points where geomagnetic variations are recorded. Inversion is performed using the ModEM software, which makes it possible to construct a model in a 400 × 400 × 200-km spatial region with the center at the Hanoi Observatory (PHU). The resulting model of the geoelectric structure contains two regional blocks separated by the Red River fault region. A conductive block is located in the southwest of the fault region, and a high-resistivity block is located in the northeast. The boundary of the blocks, inclined to the northeast at an angle of about 45°, is visible to a depth of 150 km. The conductive block occupies the region between the Red River and Song Ma faults. Its western boundary could not be localized due to insufficient data in this region. Highly conductive local blocks stand out against the background of the regional conductive block. They usually gravitate toward the faults and are located in a depth range of 10–20 km with a slight inclination to the west on latitudinal profiles and to the south on meridional ones. In a depth range of 12–14 km, they merge into one highly conductive band extending in the northwest and marking the Red River fault system connected to the Gulf of Tonkin waters. Also, there are more massive highly conductive blocks in depth intervals of 20–50 km, which are often associated with upper crustal ones. There is a highly conductive block observed on the latitudinal profile, passing through the central region of the Hanoi Basin, and steeply dipping to the east (75°) to depths of more than 100 km. The deep geoelectric features of the Red River fault system are compared with the geoelectric section under their continuation in Southern Tibet in the adjacent territory in China.

Anatomical characteristics of the phrenic nerve and the spontaneous conduction block between the right atrium and the superior vena cava

Abstract Introduction Although the superior vena cava isolation (SVCI) with minimal radiofrequency application using a spontaneous right atrium – superior vena cava (RA-SVC) conduction block has been reported, the anatomical characteristics of the spontaneous RA-SVC conduction block is not clear. Purpose The aim of this study to evaluate the anatomical relationship between the spontaneous RA-SVC conduction block and the phrenic nerve (PN). Methods This study consisted of 73 patients who attempted to undergo SVCI using a RA-SVC conduction block. The RA-SVC conduction block was visualized using the extended early meets late tool with the CARTO3 system. We set the first lower threshold at 1800/total local activation time to optimize the visualization of spontaneous RA-SVC conduction block. If the SVC was not isolated by ablation to the gap of the visualized conduction block line, the lower threshold was increased by 5%, and the new gap was ablated each time. The course of the right PN was detected by pacing with 20 mA /2 ms. The RA-SVC conduction block and the course of the PN were measured with reference to the height of the left atrial roof. The extend of the RA-SVC conduction block and PN were measured in angles with respect to the ventral side (Figure 1). These anatomical parameters were compared between the RA-SVC block line and the PN. Results Sixty-one patients (83.6%) had spontaneous RA-SVC conduction block, and the remaining 12 patients (16.4%) did not. Anatomical characteristics were evaluated in 61 patients with spontaneous RA-SVC conduction block. Compared with the course of the PN, RA-SVC conduction block extended more posteriorly (110 degrees vs 128 degrees, P = 0.013) and more caudally (9.5 mm vs 16.1 mm, P<0.0001) (Figure 2). In the patients who underwent SVCI using a RA-SVC conduction block, any patients did not undergo radiofrequency application on the course of the PN. Conclusion Since the caudal end of the RA-SVC conduction block is posterior to the caudal end of the phrenic nerve, SVCI using the RA-SVC conduction block may be able to avoid ablation near the PN.Figure1Figure2

Machine learning prediction for prognosis and long-term effectiveness for transcatheter ventricular septal defect closure: a 5-year single center experience

Abstract Background Transcatheter therapy, with minimal invasiveness and rapid recovery advantages, has emerged as the primary choice for treating perimembranous ventricular septal defect. However, patients receiving transcatheter occlusion may confront conduction abnormalities due to the occluder's proximity to the cardiac conduction bundle during implantation. Few have assessed the risks of postoperative conduction block (CB) via robust machine learning models. Purpose The purpose of this study was to evaluate our long-term follow up results of pmVSD occlusion and establish a prediction model to identify risk predictors of conduction abnormalities via robust machine learning methods. Methods Five methods including logistic regression with a stepwise selection of variables, lasso regularization; random forest; gradient descent boosting (GBM); and support vector machine, were used to train models for predicting risks of late-onset and persistent conduction block through 5 years of follow-up and were validated using 5-fold cross-validation. Receiver-operating characteristic curves and Brier scores were utilized to evaluate model discrimination and calibration, respectively. The top prediction variables were identified by using the best performing models, using the relative influence score of each variable in 5-fold cross-validation. Results The GBM model performed the best with an AUC of 0.82 (95% confidence interval [CI]: 0.75 to 0.89) for predicting late-onset CB (Brier score: 0.0204), and 0.70 (95% CI: 0.62 to 0.78) for persistent CB (Brier score: 0.0003) over entire study period. Conduction block on admission, advanced age and aortic regurgitation before discharge were strongly associated with late-onset CB, whereas decreased left ventricular ejection fraction, enlarged left ventricle end diastolic diameter at 1-month follow-up were the most significant predictors of persistent CB. Conclusions These models predict the risks of temporary and persistent postoperative conduction block in patients with pmVSD occlusion and shed light on preventing long-term complications.Study FlowchartCentral Illustration

Differences in left ventricular contraction in left bundle branch block with preserved and reduced ejection fraction: an evaluation using 2-dimensional speckle tracking echocardiography

Abstract Background Left ventricular (LV) contraction in left bundle branch block (LBBB) is characterized by early septal contraction and delayed contraction of the lateral wall, but the process may differ depending on myocardial contractility in addition to the degree of conduction block. Purpose This study aimed to evaluate LV contraction in patients with LBBB by analysis of longitudinal strain (LS) and to compare it between patients with preserved LV ejection fraction (pEF: EF>50%) and reduced LV EF (rEF: EF<40%). Methods We studied 87 patients with LBBB. Fifty had pEF (EF 59±7%) with a mean QRS duration of 144±12ms, and 38 had rEF (EF: 29±4%) with a mean QRS duration of 147±12ms (p=0.32 vs. pEF). We also studied 43 patients without conduction block (Narrow-QRS; pEF, n=23; rEF, n=20). Patients with a heart rate less than 60 or greater than 80 beats/min during echocardiography or with a history of myocardial infarction were excluded. Three standard apical images were recorded, and the LS of one heartbeat starting at the beginning of the QRS was evaluated in 18 LV segments. When the strain waveform showed a negative peak during the pre-ejection period, it was identified as early systolic contraction (ESC), and the first negative peak that appeared after aortic valve opening (AVO) was identified as late systolic contraction (LSC). The time from the beginning of QRS to the peak of the LSC (Q-Peak) and the strain value at the end of the QRS were measured in each segment. Results In patients with LBBB, the septum contracted early, and ESC was seen mainly in the early contracted area. The lateral wall contraction was delayed, and the difference between the maximum and minimum Q-Peak was greater than the Narrow-QRS in the same EF category. Patients with rEF and LBBB had a larger number of segments with ESC and a smaller minimum Q-Peak than those with pEF. The difference between the maximum and minimum Q-Peak was greater for patients with rEF than for patients with pEF. Conclusions Although patients with LBBB had significant dyssynchrony due to conduction block even those with pEF, LV contractile properties were altered in patients with rEF and associated with further increased dyssynchrony.

The connection site of the Bachmann bundle to the left atrium affects atrial electrical and anatomical remodeling

Abstract Background A common route for the propagation of the conduction system from the right atrium to the left atrium (LA) is via the Bachmann bundle (BB) which is a parallel-aligned muscular structure. It is empirically known that the site of conduction from BB to LA differs depending on the patient. Purposes To clear the clinical significance of differences in the BB conduction sites in patients with atrial fibrillation (AF). Methods We studied 182 patients (90 non-paroxysmal AF, 121 males, and 68.2 ± 10.0 years) who received catheter ablation for AF. Clinical data, echocardiographic data, and blood samples were evaluated. High-density LA mapping during high right atrial pacing was constructed. The site of conduction from BB to LA, the global activation time, LA mean voltage, the abnormal conduction zone (ACZ), and the conduction block (CBZ) were evaluated. The conduction from BB was connected to the region surrounded by the left atrial roof line, the carina of the right pulmonary vein, and the base of the left atrial appendage in all patients (Figure 1). This area was divided into four regions (right-roof, mid-roof, right-anterior, and mid-anterior area), and BB conduction sites were classified into each area by three independent observers who did not know clinical data. Global activation time for the LA was calculated by subtracting the earliest from the latest activation within the LA. Isochronal activation maps were created at a 5-ms interval setting, and ACZ (Figure 2) and CBZ were identified on the activation map by locating a site with isochronal crowding of ≥3 isochrones and ≥8 isochrones, which were calculated as ≤27 cm/s and ≤10 cm/s. Results The conduction from BB was observed in 45 patients in the right-roof area, 24 in the mid-roof, 76 in the right-anterior, 23 cases in the mid-anterior, and 14 in multiple sites. Global activation time (right-roof 108±20, mid-roof 107±16, right-anterior 105±19, and mid-anterior 117±20ms, P=0.0781) was more prolonged and left atrium diameter was larger (42.1±6.6, 42.6±8.5, 42.5±6.6, and 46.4±6.6mm, P=0.0718) in patients with mid-anterior BB connections. LA mean voltage (4.90±1.94, 5.72±2.62, 4.13±1.58, and 4.88±1.96mV, P=0.0032) was higher and plasma brain natriuretic peptide level (139±138, 67±59, 128±139, and 164±197pg/mL, P=0.0861) was lower in patients with mid-roof BB connections. ACZ (41/45 91%, 20/24 83%, 73/76 96%, and 23/23 100%, P=0.0904) and CBZ (1/45 2%, 0/24 0%, 8/76 11%, and 2/23 9%, P=0.0850) appearance rates were lower in patients with mid-roof BB connections. Conclusion The connection site of the Bachmann bundle to the left atrium may affect atrial electrical and anatomical remodeling in patients with atrial fibrillation.

Study of Conduction Blocks in ST Elevation Myocardial Infarction – A Cross-Sectional Analysis

Study of Conduction Blocks in ST Elevation Myocardial Infarction – A Cross-Sectional Analysis

Recessive Variants in PIGG Cause a Motor Neuropathy with Variable Conduction Block, Childhood Tremor, and Febrile Seizures: Expanding the Phenotype.

Biallelic variants in phosphatidylinositol glycan anchor biosynthesis, class G (PIGG) cause hypotonia, intellectual disability, seizures, and cerebellar features. We present 8 patients from 6 families with a childhood-onset motor neuropathy and neurophysiology demonstrating variable motor conduction block and temporal dispersion. All individuals had a childhood onset tremor, 5 of 8 had cerebellar involvement, and 6 of 8 had childhood febrile seizures. All individuals have biallelic PIGG variants, including the previously reported pathogenic variant Trp505*, plus 6 novel variants. Null enzyme activity is demonstrated via PIGO/PIGG double knockout system for Val339Gly and Gly19Glu, and residual activity for Trp505* due to read-through. Emm negative blood group status was confirmed in 1 family. PIGG should be considered in unsolved motor neuropathy. ANN NEUROL 2024.

Lesion size index-guided radiofrequency catheter ablation using an impedance-based three-dimensional mapping system to treat sustained atrial tachycardia in a horse.

Sustained atrial tachycardia at an atrial rate of 191/min on the surface ECG was detected in a 6-year-old Warmblood mare. The vectorcardiogram obtained from a 12-lead ECG suggested a caudo-dorsal right atrial origin of the arrhythmia. Impedance-based three-dimensional electro-anatomical mapping, using the EnSite™ Precision Cardiac Mapping System revealed a clockwise macro-reentry around a line of conduction block in the caudomedial right atrium. Ten radiofrequency applications were applied to isolate the caudal vena cava myocardial sleeves at a power of 35 W and mean contact force of 14 ± 3 g until a lesion size index of 6 was reached. Sinus rhythm was restored at the first energy application. Successful isolation was confirmed by demonstrating entrance and exit block. Holter monitoring 5 days post-ablation revealed no abnormalities. To date, 9 months after treatment, no recurrence has been observed. The use of lesion size index-guided ablation and isolation of the arrhythmogenic substrate in the caudal vena cava may minimise the risk of recurrence.

Stochastic and alternating pacing paradigms to assess the stability of cardiac conduction

Reentry, the most common cause of severe arrhythmias, is initiated by slow conduction and conduction block. Hence, evaluating conduction velocity and conduction block is of primary importance. However, the assessment of cardiac conduction safety in experimental and clinical settings remains elusive. To identify markers of conduction instability that can be determined experimentally, we developed an approach based on new pacing paradigms. Conduction across a cardiac tissue expansion was assessed in computer simulations and in experiments using cultures of neonatal murine cardiomyocytes on microelectrode arrays. Simulated and in vitro tissues were paced at a progressively increasing rate, with stochastic or alternating variations of cycle length, until conduction block occurred. Increasing pacing rate led to conduction block near the expansion. When stochastic or alternating variations were introduced into the pacing protocol, the standard deviation and the amplitude of alternating variations of local conduction times emerged as markers of unstable conduction prone to block. In both simulations and experiments, conduction delays were prolonged at the expansion but increased only slightly during the pacing protocol. In contrast, these markers of instability increased several-fold, early before block occurrence. The first and second moments of these two metrics provided an estimation of the site of block and the accuracy of this estimation. Therefore, when beat-to-beat variations of pacing cycle length are introduced into a pacing protocol, the local variability of conduction permits to predict sites of block. Our pacing paradigms may have translational applications in clinical cardiac electrophysiology, particularly in identifying ablation targets during mapping procedures.

Progress of Conductivity and Conduction Velocity Measured in Human and Animal Hearts.

Cardiac conduction velocity (CV) is a critical electrophysiological characteristic of the myocardium, representing the speed at which electrical pulses propagate through cardiac tissue. It can be delineated into longitudinal, transverse, and normal components in the myocardium. The CV and its anisotropy ratio are crucial to both normal electrical conduction and myocardial contraction, as well as pathological conditions where it increases the risk of conduction block and reentry. This comprehensive review synthesizes longitudinal and transverse CV values from clinical and experimental studies of human infarct hearts, including findings from the isthmus and outer loop, alongside data derived from animal models. Additionally, we explore the anisotropic ratio of conductivities assessed through both animal and computational models. The review culminates with a synthesis of scientific evidence that guides the selection of CV and its corresponding conductivity in cardiac modeling, particularly emphasizing its application in patient-specific cardiac arrhythmia modeling.

Flexible wide-range, sensitive three-axis pressure sensor array for robotic grasping feedback

Flexible pressure sensors capable of detecting normal and tangential forces through physical contact have garnered considerable interest in the realm of human-interactive systems. However, simultaneous detection of multi-directional forces is still a challenge for current research. Herein, a capacitive flexible pressure sensor based on a sandwich structure for three-dimensional force detection is proposed. The fabrication process of the sensor array is straightforward, capable of effectively distinguishing between normal and tangential forces. Polyimide (PI) serves as the flexible substrate for depositing the metal electrode pattern, while Polydimethylsiloxane (PDMS) acts as the intermediate dielectric layer material and the three-dimensional force conduction block. Through a comparative study of the thickness of the hollow dielectric layer, a pressure sensor with superior performance was prepared, featuring high sensitivity across a wide working range. Test results demonstrate its capability to detect normal forces ranging from 0 to 46 N (0–520 kPa) with a sensitivity of 0.442 N−1 (0.031 kPa−1) and tangential forces from 0 to 10 N with a sensitivity of 0.08 N−1 (X-axis) and 0.07 N−1 (Y-axis). The designed acquisition system can simultaneously gather data from 6 sensor arrays, totaling 240 channels, with a response time of 11 ms. This sensor array, characterized by flexibility, versatility, and a wide range, is suitable for applications in robot tactile perception.

Postmortem Identification of a Foreign Body in the Heart: A Case Report.

The presence of a foreign body in the heart have been reported, mostly in adults. Deaths and injuries can result from the breakage or rupture of angiography catheters. We present a case in which an angiocath tip was identified in the right ventricle of a pediatric patient, and the patient died as a result thereof. As no similar cases have been reported, we would like to draw attention to this subject. A 4.5-month-old female patient who was hospitalized 3 times during her life had a history of peripheral venous access establishment in the extremities with angiocatheters. During these hospital admissions, a central catheter was not inserted, and no additional problems were identified. Emergency personnel responded and found the patient at home, experiencing bradycardia and arrhythmia. She was resuscitated and taken to the hospital, where she died. The autopsy revealed, the tip of a 1.5cm long, 1mm wide lumen catheter had penetrated the right ventricular wall (Fig.1) (Fig.2), thus her death was attributed to complications that developed as a result of the peripheral vascular access catheter tip breaking and migrating to the right ventricle. Although the patient did not have an ECG, physical examination by the emergency ambulance personnel revealed an irregular and bradycardic heartbeat, suggesting that the child may have developed arrhythmia and atrioventricular conduction block. Health care professionals must check upon removal of peripheral intravenous access, and record whether the integrity of the peripheral catheter tip was compromised to prevent similar events in future. Fig.1 Angiocath tip piercing the right ventricular wall and exiting the heart Fig.2 a A 1.5cm long, b 1mm wide lumen catheter tip penetrating the right ventricular wall.

Sinoatrial node function and the role of sinoatrial conduction in the typical atrial flutter substrate

BackgroundSinoatrial node (SAN) activation and sinoatrial conduction pathways (SACPs) have been assessed in animals but not in humans. ObjectivesWe used ultrahigh-density mapping and simulated models to characterize the SAN and to investigate whether slowed SAN conduction may contribute to the atrial flutter (AFL) substrate. MethodsTwenty-seven patients undergoing electrophysiologic procedures had right atrial mapping. SAN activation patterns and conduction block were analyzed. The interaction between the SAN and the intercaval line of block (LOB) was analyzed, and right atrial simulations with different degrees of block were created to investigate arrhythmia mechanisms. ResultsFifteen AFL patients and 12 reference patients were enrolled. SACPs were identified in all patients with sinus rhythm maps. An SAN-adjacent LOB was observed in AFL patients. SAN conduction velocity was slower in AFL vs reference (0.60 m/s [0.56–0.78 m/s] vs 1.13 m/s [1.00–1.21 m/s]; P = .0021). Coronary sinus paced maps displayed an intercaval LOB in AFL patients but not in reference patients, which was completed superiorly by the SAN-adjacent LOB. Corrected sinus node recovery time was longer in AFL patients (552.3 ± 182.9 ms vs 325.4 ± 138.3 ms; P < .006) and correlated with degree of intercaval block (r = 0.7236; P = .0003). Computer modeling supported an important role of SAN-associated block in the flutter substrate. ConclusionUltrahigh-density mapping accurately identifies SAN activation and SACPs. The LOB important for typical AFL was longer in AFL patients, and when partial, it was always present inferiorly and completed superiorly because of slowed conduction across the SAN. Corrected sinus node recovery time correlated with intercaval block, suggesting a role for SAN disease in the genesis of the typical AFL substrate.

Estimating the Concentration of Heavy Metals in Oleander/Pink and white Oleander Plants

Oleander is a large ornamental evergreen shrub that may grow 20–25 ft in height. During the summer months’ large clusters of white, pink, red, or yellow (yellow oleander) flowers appear at the ends of the branches. All parts of the plant contain cardiac glycosides. Oleander is a common source of serious plant poisoning. In South Asia, particularly Sri Lanka, also present in Libya desert and some house gardens with white and pink types, oleander has become a notorious method of suicide. Toxicity is largely characterized by gastrointestinal symptoms and cardiac abnormalities. Tachy or bradydysthythmias may be present in addition to slowed conduction and heart block. Hyperkalemia is common and correlates with severity of poisoning. A specific antidote—digoxin-specific fragment antigen-binding region (Fab region)- is available. In Mediterranean climates oleanders can be expected to bloom from April through October, with the heaviest bloom usually occurring between May and June. Free-flowering varieties like 'Petite Salmon' or 'Mont Blanc' require no period of rest and can flower continuously throughout the year if the weather remains warm. The exact nature of plant poisoning varies from region to region, but certain plants are almost ubiquitous in distribution and among these, Oleander is a garden plant that features in many homes. Incidents of poisoning from these plants are therefore not uncommon and may be the result of accidental exposure or deliberate, suicidal ingestion of the toxic parts. An attempt has been made to review the management principles with regard to toxicity of these plants and survey the literature in order to highlight current concepts in the treatment of poisoning resulting from both plants. Ingestion of its seeds results in a clinical picture similar to digoxin toxicity. It contains cardiac glycosides that are toxic to cardiac myocytes and autonomic system. Cardiac glycosides of oleander cause poisoning by inhibiting plasmalemmal Na+/K+-ATPase. Results: The poisoning effects of plant or their active alkaloids induced infiltration of cells with hemorrhage and sever negative changes in the lung, induce lesions, and infiltration of inflammatory cells into the portal spaces with scattered necrosis of hepatocytes in the liver, cardiac toxicity of the plant in the heart were included, induced varying degrees of hemorrhage, myocardial degeneration, and necrosis. It also induced arrhythmia, sinus bradycardia, and prolonged P-R interval in electrocardiographic records. Conclusions: The toxic effects of N. oleander are mostly related to its inhibitory effects on the Naþ-Kþ ATPase pump in the cellular membrane. However, the exact molecular mechanism involved in the toxicity of N. oleander is not clear.

Airborne polystyrene nanoplastics exposure leads to heart failure via ECM-receptor interaction and PI3K/AKT/BCL-2 pathways

Environmental contamination has been recognized as a significant threat to human well-being, and recent findings of microplastic presence in human cardiac tissues have raised concerns. However, research on the effects of airborne nanoplastics (NPs) on cardiac physiology remains limited. We utilized a comprehensive body exposure apparatus to simulate the impact of airborne polystyrene NPs pollution, focusing on understanding how airborne NPs affect cardiac morphology and function. Following two weeks of NPs exposure, mice exhibited a 23.89 ± 8.30 % reduction in heart mass, a 20.05 ± 2.97 % decrease in heart rate as detected, and a myocardial electrical conduction block. Echocardiography showed significant changes in cardiac contractility, with increases in cardiac ejection fraction and stroke volume of 13.00 ± 3.00 % and 43.00 ± 17.00 %, respectively. In addition, histologic assessments revealed signs of ventricular hypertrophy, ventricular myocardial hypertrophy, and myocardial necrotic fibrosis. Of particular interest, our mechanistic investigations highlighted the harmful effects of NPs on cardiac structure and function, mediated through extracellular matrix (ECM) receptor interactions and the PI3K/AKT/BCL-2 signaling pathway. The insights gained provide a foundation for understanding the risks posed by airborne NPs to human cardiac health, emphasizing the need for increased vigilance and implementation of mitigation strategies in environmental management.

Lessons from ablation responses to preferential wavefront in typical atrial flutter.

The heterogeneous conduction properties through the cavotricuspid isthmus (CTI) in typical atrial flutter (AFL) have not yet been well elucidated. We sought to investigate preferential conduction through the CTI and the efficacy of ablation targeting preferential wavefront (PW) guided by ultra-high-resolution mapping. In retrospective study, 28 patients were enrolled. Wavefront propagation patterns through the CTI and ablation responses at the location of PW were evaluated. In the following prospective study, 23 patients with predominant PW across the CTI were enrolled and assigned to the arm of PW prior ablation and the arm of conventional ablation. Five activation patterns were noticed in the retrospective study. The termination sites were exactly located at the PW in 18 of 28 patients (64.3%). The width of the PW in direct termination group was significantly narrower than that in the CL prolongation before termination group (16.6 ± 1.0mm vs. 23.3 ± 3.4mm, respectively, p = 0.025). In the prospective study, the voltage of PW region was significantly higher than non-PW regions both from unipolar and bipolar mapping. 21 of 23 patients (91.3%) were terminated at PW. AFL could no longer be induced immediately after termination. The time from radiofrequency application to AFL termination and to achieve bidirectional conduction block was significantly shorter in PW prior ablation arm than that in conventional ablation group (p < 0.05). Ablation targeting the PW first could be more efficient to terminate typical AFL and to achieve the endpoint of bidirectional conduction block.

Multifocal motor neuropathy in Japan: A nationwide survey on prevalence, clinical profiles, and treatment.

Multifocal motor neuropathy (MMN) is a rare disease for which epidemiological and clinical data are limited. We conducted a nationwide survey to determine disease prevalence, incidence, clinical profile, and current treatment status in Japan. A nationwide survey was conducted in 2021 using an established epidemiological method. Questionnaires were sent to all neurology and pediatric neurology departments in Japan. An initial questionnaire was administered to determine the number of patients with and incidence of MMN. A second questionnaire was administered to collect detailed clinical information. The European Federation of Neurological Societies/Peripheral Nerve Society 2010 guidelines were used as diagnostic criteria. The estimated number of patients with MMN was 507. The estimated prevalence was 0.40 per 100,000 individuals. Detailed clinical profiles were available for 120 patients. The male-to-female ratio was 2.3:1 and the median onset age was 42 years. The median disease duration at diagnosis was 25 months. Most patients presented with upper limb-dominant muscle weakness. Motor nerve conduction blocks were found in 62% of patients and positive anti-GM1 IgM antibody results in 54%. A total of 117 (98%) patients received immunoglobulin therapy, and 91% of them showed improvement. At the time of the last visit (median, 82 months from treatment initiation), 89 (74%) patients were receiving maintenance immunoglobulin therapy. A slight progression of neurological deficits was observed during follow-up. Most patients with MMN in Japan received induction and maintenance immunoglobulin therapies, which appear to suppress long-term disease progression.