Accumulated ß-catenin is associated with human atrial fibrosis and atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with increased risk of stroke and mortality. It has been reported that the process of atrial fibrosis was regulated by ß-catenin in rats with AF. However, pathophysiological mechanisms of this process in human with AF remain unclear. This study aims to investigate the possible mechanisms of ß-catenin in participating in the atrial fibrosis using human right atrial appendage (hRAA) tissues . METHODS: We compared the difference of ß-catenin expression in hRAA tissues between the patients with AF and sinus rhythm (SR). The possible function of ß-catenin in the development of AF was also explored in mice and primary cells. RESULTS: Firstly, the space between the membrane of the gap junctions of cardiomyocytes was wider in the AF group. Secondly, the expression of the gap junction function related proteins, Connexin40 and Connexin43, was decreased, while the expression of ß-catenin and its binding partner E-cadherin was increased in hRAA and cardiomyocytes of the AF group. Thirdly, ß-catenin colocalized with E-cadherin on the plasma membrane of cardiomyocytes in the SR group, while they were dissociated and accumulated intracellularly in the AF group. Furthermore, the expression of glycogen synthase kinase 3ß (GSK-3ß) and Adenomatous Polyposis Coli (APC), which participated in the degradation of ß-catenin, was decreased in hRAA tissues and cardiomyocytes of the AF group. Finally, the development of atrial fibrosis and AF were proved to be prevented after inhibiting ß-catenin expression in the AF model mice. CONCLUSIONS: Based on human atrial pathological and molecular analyses, our findings provided evidence that ß-catenin was associated with atrial fibrosis and AF progression.

Right Ventricular Longitudinal Shortening is not Associated with Left Ventricular Rotational Mechanics in Healthy Adults - Insights from the Three-dimensional Speckle-tracking Echocardiographic MAGYAR-Healthy Study.

Background: The left ventricle (LV) not only contracts, but its rotational mechanics have a significant role in systolic ejection, whereas the right ventricle (RV) is substantially different in shape and function, and its contractility is not accompanied by rotational features. Simple M-mode echocardiography-based tricuspid annular plane systolic excursion (TAPSE) reflects RV longitudinal contraction or shortening. The aim of the present study was to examine the relationship between the parameters characterizing the rotational mechanics of the LV as assessed by three-dimensional speckle-tracking echocardiography (3DSTE) and the TAPSE. The effects of different degrees of these parameters on each other were also examined. Methods: The present retrospective analysis evaluated the results of 80 healthy adult individuals with an average age of 28.1 ± 6.3 years (33 males) with LV rotational mechanics being directed normally. All cases have undergone complete two-dimensional Doppler echocardiography with the measurement of TAPSE and 3DSTE. Results: None of the LV volumes and rotational parameters showed any differences in healthy cases with TAPSE 18-21 mm vs. TAPSE > 22 mm. Similarly, right atrial (RA) volumetric parameters did not differ either. TAPSE showed no associations with the degree of basal LV rotation. RA volumes were slightly increased with higher basal LV rotation. Similar to basal LV rotation, TAPSE did not change with the degree of apical LV rotation and a tendentious increase of RA volumes could be demonstrated with increasing apical LV rotation. No correlation could be demonstrated between apical and basal LV rotations and TAPSE. Conclusions: 3DSTE-derived LV rotational parameters and TAPSE are not associated suggesting that LV twist is independent of RV longitudinal shortening in healthy circumstances.

Age- and Sex-Specific MR-Feature Tracking Reference Values of Right Atrial Deformation in Healthy Adults.

BACKGROUND: Although right atrial (RA) myocardial deformation has important implications for patient diagnosis, prognosis, and risk stratification, its implementation in clinical practice has been hampered by limited normal reference values, especially in Asian populations. PURPOSE: To establish age- and sex-specific reference values for RA strain, strain rate (SR), and displacement based on a large sample of healthy Chinese adults using MR-feature tracking (MR-FT). STUDY TYPE: Retrospective. POPULATION: 524 healthy Chinese adults (287 male; mean age 43.7 ± 11.9 years). FIELD STRENGTH/SEQUENCE: 1.5T/balanced steady-state free precession. ASSESSMENT: RA deformation parameters, including reservoir, conduit, and booster strain (εs, εe, and εa), peak positive, early negative, and late negative SR (SRs, SRe, and SRa), and total, passive, and active displacement (Ds, De, and Da), were assessed using MR-FT. STATISTICAL TESTS: Student's t-test, one-way ANOVA, coefficients of determination (r2 ), intraclass correlation coefficients (ICC), and Bland-Altman plots. A P value <0.05 was considered significant. RESULTS: Women demonstrated significantly greater magnitudes of RA deformation parameters than men: εs (57.4% ± 15.1% vs. 44.3% ± 12.6%), εe (37.5% ± 13.4% vs. 27.4% ± 10.9%), εa (19.9% ± 5.7% vs. 16.9% ± 5.0%), SRs (2.62 ± 0.88 sec-1 vs. 2.00 ± 0.63 sec-1 ), SRe (-2.98 ± 1.26 sec-1 vs. -2.16 ± 0.92 sec-1 ), SRa (-2.28 ± 0.75 sec-1 vs. -1.84 ± 0.62 sec-1 ), Ds (-7.80 ± 1.90 mm vs. -7.46 ± 1.70 mm), and De (-4.84 ± 1.31 mm vs. -4.49 ± 1.21 mm). For both sexes, aging was significantly associated with decreased RA reservoir and conduit function (εs, SRs, Ds, εe, SRe, and De), and with increased εa and Da. RA deformation measurements had good to excellent intraobserver and interobserver reproducibility, with ICCs ranging from to 0.790 to 0.972. DATA CONCLUSION: This study provides age- and sex-specific reference values of RA strain, SR, and displacement based on a large cohort of healthy Chinese adults using MR-FT. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

A rare case of an unexpected trigger of paroxysmal atrial fibrillation in the right atrial appendage diverticulum.

INTRODUCTION: We described a rare case of an adolescent girl with paroxysmal atrial fibrillation originating from the right atrial appendage diverticulum and successfully converted to sinus rhythm after surgical intervention. METHODS: A 19-year-old girl was referred to the hospital for a catheter ablation of paroxysmal atrial fibrillation. conventional radiofrequency ablation using 3-D mapping were ineffective. Activation mapping showed the root of the free wall atrial appendage was first excited and catheter modeling (3D Carto map) showed a sac-like structure. RESULTS: We did selective angiography and further Computed tomography angiography (CTA) and Transesophageal echocardiography (TEE) which showed diverticulum originating from the right atrial appendage. Hence the patient was referred to cardiac surgery and had no recurrent atrial fibrillation at three months postoperative follow up. CONCLUSIONS: Right atrial appendage diverticulum was an extremely rare malformation that can coexist with atrial tachyarrhythmia. Surgical ligation or excision of the abnormal structure with local ablation can achieve excellent results.

Leadless pacemaker implementation at the right atrial appendage apex: An initial preclinical assessment.

OBJECTIVE: This study evaluates the feasibility and efficacy of implanting a leadless pacemaker at the right atrial appendage (RAA) in a preclinical minipig model, aiming to address the limitations of atrial pacing with current leadless devices like the Medtronic Micra, which is typically used for right ventricular implantation. METHODS: Four minipigs, each with a median body weight of 45.8 ± 10.0 kg, underwent placement of the Micra transcatheter pacing system (TPS) via the right femoral vein into the RAA apex. The pacing performance was assessed over 1-week (short-term) and 3-month (long-term) periods. OUTCOMES: The initial findings indicated successful implantation, with satisfactory intrinsic R-wave amplitudes and pacing threshold. In the following period, the sensitivity, threshold, and impedance were stable with time. Notably, upon explanation at 3 months, a deep myocardial penetration by the device was observed, necessitating a redesign for safe long-term use in a growing subject's heart. CONCLUSION: While initial results suggest that RAA apex placement of the Micra TPS is promising for potential inclusion in a dual-chamber pacing system, the issue of myocardial penetration highlights the need for device redesign to ensure safety and effectiveness in long-term applications.

Prognostic value of right atrial strain in systemic sclerosis based on tissue tracking analysis using cine cardiac magnetic resonance imaging: a retrospective observational study.

Interstitial lung disease and cardiac involvement are common manifestations and prognostic factors of systemic sclerosis. However, it is unclear whether impaired right atrial function associated with interstitial lung disease in systemic sclerosis can be used as a prognostic factor in this patient population. Therefore, this study aimed to investigate the relationship between right atrial function, interstitial lung disease, and prognosis in patients with systemic sclerosis using tissue tracking analysis with cine cardiac magnetic resonance imaging. In this retrospective observational study, a total of 40 patients with systemic sclerosis were enrolled. Tissue tracking analysis was used to obtain time curves of right atrial strain. Reservoir (total strain), conduit (passive strain), and booster (active strain) pump function were calculated, and right atrial strain, interstitial lung disease, and clinical outcomes were examined. An adverse clinical event was defined as all-cause death. Overall, 23 patients had interstitial lung disease (58%). Six patients died during the follow-up (median, 44 months). The total skin score and right ventricular systolic pressure on echocardiography were higher in patients with an event than in those without an event (28 ± 16% vs. 13 ± 13%, P = 0.02; 46.3 ± 10.7 mmHg vs. 36.0 ± 8.5 mmHg, P = 0.01, respectively). Further, right atrial total strain and active strain were significantly lower in patients with an event than in those without an event (14.3 ± 11.3% vs. 25.8 ± 11.4%, P = 0.03; 3.48 ± 2.37 vs. 11.7 ± 6.78, P = 0.007, respectively). Multivariate analysis revealed that active strain was an independent predictor of all-cause death (hazard ratio 0.76, P = 0.029). Kaplan-Meier analysis revealed that the survival rate was significantly higher in patients with right atrial active strain levels above the cutoff 7.4 (P < 0.05). In systemic sclerosis, right atrial booster function was predictive of mortality. Hence, right atrial functional assessment may have incremental prognostic value for patients with systemic sclerosis, leading to better risk stratification.

Prognostic impact of right atrial strain in systemic lupus erythematosus with pulmonary arterial hypertension.

OBJECTIVE: The aim of this study was to assess right atrial (RA) function, including RA phase strain, via speckle-tracking echocardiography (STE) in a cohort of systemic lupus erythematosus (SLE) patients with pulmonary arterial hypertension (PAH) and in particular to explore the relationship between RA phase strain and the occurrence of cardiovascular events. METHODS: STE analyses of RA function were evaluated in patients with SLE-PAH and in 33 healthy control subjects. Clinical associations, serum biomarkers, echocardiographic data, survival times, and adverse cardiovascular events were evaluated. RESULTS: A total of 66 patients with SLE-PAH were enrolled; they were divided into two groups based on the occurrence of adverse clinical events. RA phase strain was significantly reduced in patients with events than in patients without events. The endpoint was defined as the combined outcome of all-cause mortality, right heart failure, and rehospitalization due to disease progression. During a mean follow-up of 17.2 ± 9.9 months, 23 patients (35%) reached the endpoint. Compared with patients with RA reservoir strain (RASr) ≥33.45%, patients with RASr < 33.45% had more adverse long-term outcomes (log rank p < .0001). RASr was independently associated with adverse clinical outcomes according to multivariate analysis (p = .010). CONCLUSION: Our data suggest that RA function has prognostic value for SLE-PAH patients, and strain analysis revealed that the worse the RA function is, the worse the prognosis.

Prominent crista terminalis mimicking a right atrial mass: a systematic literature review and meta-analysis.

The crista terminalis is an anatomical structure localized on the posterolateral wall of the right atrium (RA). We performed a systematic review of the literature and meta-analysis concerning cases of unusual prominent crista terminalis mimicking RA mass. Moreover, we described the differential diagnosis of cardiac masses with the use of echocardiography, computed tomography, and cardiac magnetic resonance (CMR). We also emphasize the potential importance of this structure in electrophysiological procedures, including its role in exaggerated arrhythmias. Prominent crista terminalis may be a potential obstacle during invasive cardiac procedures or catheter ablation target. In analyzed cases, the crista terminalis was often erroneously interpreted as pathologic and at first confused with a thrombus or tumor during transthoracic echocardiography examination. The correct final diagnoses were mostly made with used transesophageal echocardiography or CMR. The most important imaging findings suggestive of prominent crista terminalis rather than tumor were a similar echogenicity/intensity with adjacent myocardium, the location on posterolateral wall of the RA, the phasic change in size, and no enhancement after contrast injection. We describe up to date and detailed imaging features for the differential diagnostics of selected intracardiac masses using various imaging techniques, including multimodality cardiac imaging. Familiarity with the anatomy and the imaging findings of the prominent crista terminalis will reduce misdiagnosis and avoid additional tests and unwarranted clinical interventions, while in patients considered for invasive cardiac procedures it might increase their efficacy and safety.

Quantitative Analysis of Right Atrial Functions by 2D-Speckle Tracking Echocardiography During Healthy Pregnancy.

BACKGROUND: The role of speckle tracking in the assessment of right atrial (RA) deformation parameters has not been investigated yet. The purpose of this article is to establish the effects of normal pregnancy on RA mechanical changes obtained by 2-dimensional speckle-tracking echocardiography. METHODOLOGY: A total of 49 healthy pregnant women were included in the study. All participants were followed for each trimester and postpartum period, encompassing standard assessments of both RA and ventricular functions, as well as measurements of RA global peak atrial longitudinal strain (RA-Global-PALS) and RA global peak atrial contraction strain (RA-Global-PACS). Additionally, the RA segments were individually evaluated with respect to strain parameters. RESULTS: During pregnancy, the increased volume load resulted in elevated RA reservoir function, as indicated by RA-Global-PALS, and increased contraction parameter, as indicated by RA-Global-PACS. These changes were within physiological limits and reversible. Segmental analysis of the right atrium showed similar findings for regional PACS and PALS parameters. CONCLUSION: In this study, we established normal RA deformation parameters for healthy pregnancies. These data will aid in discerning various measures of RA phasic function in cardiovascular and systemic conditions among normal pregnant women. Moreover, they may offer insights into potential cardiac pathologies that may arise during the pregnancy.

Clinical Presentation and Therapy of Atrioventricular Septal Defect.

Atrioventricular septal defects (AVSDs) consist of a number of cardiac malformations that result from abnormal development of the endocardial cushions. AVSDs occur in 0.19 of 1000 live births and constitute 4-5 % of congenital heart defects. AVSDs can be categorized as incomplete (or partial) or complete, and intermediate or transitional.

Right Atrial Strain in Pediatric Pulmonary Hypertension-A Prospective Observational Study.

Right ventricular (RV) afterload due to elevated pulmonary arterial (PA) pressure in pulmonary hypertension (PH) causes long-term right atrial (RA) remodeling and dysfunction. RA function has been shown to correlate with PA pressures and outcome in both adult and pediatric patients with PH. We studied the role of RA strain in estimating PA pressures in congenital heart disease (CHD)-associated PH. Children below 12 years undergoing elective repair of CHD with left-to-right shunts and echocardiographic evidence of PH were included. RA reservoir, conduit and contractile strain along with conventional measures of RV function and PA pressure were measured using transthoracic echocardiography after induction of anaesthesia. Pre-and post-repair invasive PA pressures were measured after surgical exposure. 51 children with a median age of 24 months (range 4-144 months) were included, most of whom were undergoing VSD closure. Contractile RA strain showed good correlation with pre-repair systolic PA pressure in mmHg (r = 0.59, 95%CI 0.37-0.75) or expressed as a percentage of SBP (r = 0.67, 95%CI 0.49-0.80). It also predicted persistent postoperative PH as well as pre-repair pulmonary artery acceleration time and right ventricular systolic pressure measured from tricuspid regurgitation jet. The trends of correlation observed suggest a possible prognostic role of RA strain in ACHD with PH and potential utility in its echocardiographic assessment. The observed findings merit deeper evaluation in larger cohorts.

Left ventricle-right atrial communication: A specific type of ventricular septal defect.

Left ventricular-right atrial communication (LV-RAC) refers to the shunt from the left ventricle to the right atrium caused by an abnormal channel between the left ventricle and the right atrium, and is a specific type of ventricular septal defect that is rare. We diagnosed one case using echocardiography.

Autonomic function and specific right atrial functions - Is there a relationship? Correlations from the three-dimensional speckle-tracking echocardiographic MAGYAR-Healthy Study.

INTRODUCTION: Similarly to the ventricles, the atria are under sympathetic/parasympathetic neural regulation. Accordingly, correlations were investigated between Ewing's standard cardiovascular reflex tests (SCRTs) and three-dimensional speckle-tracking echocardiography (3DSTE)-derived right atrial (RA) volumes and strains in healthy subjects. MATERIALS AND METHODS: The study comprised 45 healthy adults, but 5 subjects were excluded due to inferior image quality for 3DSTE-derived RA assessments. The remaining 40 individuals being in sinus rhythm had a mean age of 35.1 ± 3.5 years (20 men). Two-dimensional, Doppler, 3DSTE and SCRTs were performed in all cases. RESULTS: RA maximum volume and total and passive RA stroke volumes correlated with the Valsalva ratio. Active RA stroke volume and emptying fraction showed correlations with 30/15 ratio. Peak global and mean segmental RA circumferential (CS) and longitudinal strains (LS) showed correlation with the Valsalva ratio. At atrial contraction, global RA-LS and mean segmental RA-CS showed correlations with the Valsalva ratio. Moreover, mean segmental RA-CS correlated with 30/15 ratio and mean segmental RA radial strain showed correlations with systolic blood pressure in response to standing. Autonomic neuropathy score correlated with peak global RA-LS. CONCLUSIONS: Autonomic function parameters have significant associations with specific RA functions in healthy adults, making the latter possible indicators of autonomic dysregulation.

Positive correlation between echocardiographic tricuspid E peak velocity and central venous pressure in dogs: A preliminary study.

In the absence of vascular obstruction, central venous pressure (CVP) is a hydrostatic pressure in the cranial and caudal vena cava, providing valuable information about cardiac function and intravascular volume status. It is also a component in evaluating volume resuscitation in patients with septic shock and monitoring patients with right heart disease, pericardial disease, or volume depletion. Central venous pressure is calculated in dogs by invasive central venous catheterization, which is considered high-risk and impractical in critically ill patients. This study aimed to investigate the feasibility of using echocardiographic tricuspid E/E' as a noninvasive method to estimate CVP in anesthetized healthy dogs under controlled hypovolemic conditions. Ten male mixed-breed dogs were included in the study after a thorough health assessment. For hypovolemia induction, blood withdrawal was performed, and echocardiographic factors of the tricuspid valve, including peak E and E' velocities, were measured during CVP reduction. Repeated measures analysis of variance and Bonferroni post hoc tests were employed to compare the average difference between measured echocardiographic indices and CVP values derived from catheterization and intermittent measurement methods. Spearman's ρ correlation coefficient was used to evaluate the correlation between echocardiographic indices and CVP. E peak velocity had a significant negative correlation with venous blood pressure phases (r = -0.44, P = .001), indicating a decrease in peak E velocity with progressive CVP reduction. However, tricuspid valve E' peak velocity and E/E' did not correlate with CVP, suggesting that these parameters are not reliable for CVP estimation in dogs.

Structural characteristics of patients with superior vena cava foci initiating atrial fibrillation: Analysis with electrocardiogram-triggered computed tomography.

INTRODUCTION: The superior vena cava (SVC) is the most common source of non-pulmonary vein foci in atrial fibrillation (AF); therefore, predicting the existence of non-pulmonary vein foci before the catheter ablation procedure helps construct a proper ablation strategy in preparation for SVC isolation. This study aimed to clarify the structural characteristics of patients with SVC foci initiating AF. METHODS: We enrolled 331 consecutive patients with AF who underwent cardiac computed tomography imaging before radiofrequency catheter ablation treatment, and they were divided into SVC (+) and (-) groups based on the presence or absence of SVC foci initiating AF. RESULTS: The SVC (+) group (n = 27) exhibited SVC crescent signs-defined as a curve-shaped SVC with two narrow pointed ends-more frequently (37% vs. 9%, p < .001), and larger right atrial volume (95.6 ± 20.8 vs. 80.5 ± 26.1 mL, p = .004) than the SVC (-) group (n = 304). Multivariate logistic regression analysis revealed that the SVC crescent sign (odds ratio, 8.88; 95% confidence interval [CI], 3.21-24.60) and right atrial volume (odds ratio, 1.03; 95% CI, 1.01-1.04) were independent predictors of SVC foci. CONCLUSION: Patients with SVC foci exhibited more frequent SVC crescent signs and larger right atrial volumes, and these characteristics may help clinicians choose the appropriate ablation technology.

Right Heart Adaptation to Exercise in Pulmonary Hypertension: An Invasive Hemodynamic Study.

BACKGROUND: Right heart failure (RHF) is associated with a dismal prognosis in patients with pulmonary hypertension (PH). Exercise right heart catheterization may unmask right heart maladaptation as a sign of RHF. We sought to (1) define the normal limits of right atrial pressure (RAP) increase during exercise; (2) describe the right heart adaptation to exercise in PH owing to heart failure with preserved ejection fraction (PH-HFpEF) and in pulmonary arterial hypertension (PAH); and (3) identify the factors associated with right heart maladaptation during exercise. METHODS AND RESULTS: We analyzed rest and exercise right heart catheterization from patients with PH-HFpEF and PAH. Right heart adaptation was described by absolute or cardiac output (CO)-normalized changes of RAP during exercise. Individuals with noncardiac dyspnea (NCD) served to define abnormal RAP responses (>97.5th percentile). Thirty patients with PH-HFpEF, 30 patients with PAH, and 21 patients with NCD were included. PH-HFpEF were older than PAH, with more cardiovascular comorbidities, and a higher prevalence of severe tricuspid regurgitation (P < .05). The upper limit of normal for peak RAP and RAP/CO slope in NCD were >12 mm Hg and ≥1.30 mm Hg/L/min, respectively. PH-HFpEF had higher peak RAP and RAP/CO slope than PAH (20 mm Hg [16-24 mm Hg] vs 12 mm Hg [9-19 mm Hg] and 3.47 mm Hg/L/min [2.02-6.19 mm Hg/L/min] vs 1.90 mm Hg/L/min [1.01-4.29 mm Hg/L/min], P < .05). A higher proportion of PH-HFpEF had RAP/CO slope and peak RAP above normal (P < .001). Estimated stressed blood volume at peak exercise was higher in PH-HFpEF than PAH (P < .05). In the whole PH cohort, the RAP/CO slope was associated with age, the rate of increase in estimated stressed blood volume during exercise, severe tricuspid regurgitation, and right atrial dilation. CONCLUSIONS: Patients with PH-HFpEF display a steeper increase of RAP during exercise than those with PAH. Preload-mediated mechanisms may play a role in the development of exercise-induced RHF.

Estimated glomerular filtration rate, haemodynamics, and mortality in patients with aortic stenosis.

BACKGROUND: In aortic stenosis (AS), estimated glomerular filtration rate (eGFR) is an important prognostic marker but its haemodynamic determinants are unknown. We investigated the correlation between eGFR and invasive haemodynamics and long-term mortality in AS patients undergoing aortic valve replacement (AVR). METHODS: We studied 503 patients [median (interquartile range) age 76 (69-81) years] with AS [indexed aortic valve area .42 (.33-.49) cm2 /m2 ] undergoing cardiac catheterization prior to surgical (72%) or transcatheter (28%) AVR. Serum creatinine was measured on the day before cardiac catheterization for eGFR calculation (CKD-EPI formula). RESULTS: The median eGFR was 67 (53-82) mL/min/1.73 m2 . There were statistically significant correlations between eGFR and mean right atrial pressure (r = -.13; p = .004), mean pulmonary artery pressure (mPAP; r = -.25; p < .001), mean pulmonary artery wedge pressure (r = -.19; p < .001), pulmonary vascular resistance (r = -.21; p < .001), stroke volume index (r = .16; p < .001), extent of coronary artery disease, and mean transvalvular gradient but not indexed aortic valve area. In multivariate linear regression, higher age, lower haemoglobin, lower mean transvalvular gradient (i.e. lower flow), lower diastolic blood pressure, and higher mPAP were independent predictors of lower eGFR. After a median post-AVR follow-up of 1348 (948-1885) days mortality was more than two-fold higher in patients in the first eGFR quartile compared to those in the other three quartiles [hazard ratio 2.18 (95% confidence interval 1.21-3.94); p = .01]. CONCLUSION: In patients with AS, low eGFR is a marker of an unfavourable haemodynamic constellation as well as important co-morbidities. This may in part explain the association between low eGFR and increased post-AVR mortality.

Anatomic, histologic, and mechanical features of the right atrium: implications for leadless atrial pacemaker implantation.

BACKGROUND: Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known. OBJECTIVES: We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human. METHODS AND RESULTS: Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery. CONCLUSIONS: Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations.

Mapping-guided atrial lead placement determines optimal conduction across Bachmann's bundle: a rationale for patient-tailored pacing therapy.

AIMS: Conventional right atrial appendage (RAA) pacing is associated with increased atrial activation time resulting in higher incidences of atrial tachyarrhythmia. Optimal pacing sites ideally shorten inter-atrial conduction delay, thereby decreasing atrial excitation time. We therefore examined the impact of programmed electrical stimulation (PES) from the right atrium (RA) and left atrium (LA) on the electrophysiological properties of Bachmann's bundle (BB). METHODS AND RESULTS: High-resolution epicardial mapping of BB was performed during sinus rhythm (SR) and PES in 34 patients undergoing cardiac surgery. Programmed electrical stimulation was performed from the RAA, junction of the RA with inferior caval vein (LRA), and left atrial appendage (LAA). Pacing from either the RAA or LAA resulted in, respectively, right- and left-sided conduction across BB. However, during LRA pacing in most patients (n = 15), activation started in the centre of BB. The total activation time (TAT) of BB during RAA pacing [63 (55-78) ms] was similar to that of SR [61 (52-68) ms, P = 0.464], while it decreased during LRA [45 (39-62) ms, P = 0.003] and increased during LAA pacing [67 (61-75) ms, P = 0.009]. Reduction of both conduction disorders and TAT was most often achieved during LRA pacing (N = 13), especially in patients who already had a higher amount of conduction disorders during SR [9.8 (7.3-12.3) vs. 4.5 (3.5-6.6)%, P < 0.001]. CONCLUSION: Pacing from the LRA results in a remarkable decrease of TAT compared with pacing from the LAA or RAA. As the most optimal pacing site varies between patients, individualized positioning of the atrial pacing lead guided by mapping of BB may be one of the new frontiers for atrial pacing.

Unexpected TEE Findings During Rheumatic Triple-Valve Surgery: Incidental, Yet Impactful.

This E-Challenge highlights an incidental prebypass transesophageal echocardiographic (TEE) finding of a right atrial membrane that impacted cardiac surgical management during triple-valve surgery. Two-dimensional and advanced 3-dimensional (3D) TEE were used in real-time to assist intraoperative decision-making. The findings, clinical course, discussion of the differential diagnosis, final diagnosis, and patient management are detailed here.