Continuing Medical Education Program in Echocardiography

Funding AcknowledgementsType of funding sources: None.BackgroundAtrial extrasystoles (AES) originating from the pulmonary veins are notorious for triggering episodes of atrial fibrillation (AF). However, non-pulmonary vein triggers, emerging from e.g. the superior vena cava, left atrial posterior free wall, left atrial appendage (LAA), terminal crest and interatrial septum, play also an important role in a significant part of AF patients. AES provoke conduction disorders due to (dispersion in) refractoriness and enhanced non-uniform anisotropy of atrial tissue, which are related to initiation and perpetuation of AF. Bachmann’s bundle (BB) is the main route for interatrial conduction and plays a key role in AF development. However, the exact mechanistic effects of AES on BB in AF initiation are still unknown.PurposeTo examine the impact of programmed electrical stimulation (PES) from the left and right atrium on activation and electrophysiological features of BB.MethodsIntra-operative high-resolution epicardial mapping of BB was performed during sinus rhythm (SR) in 30 patients (27 male, 64±10 years). PES included a S1 sequence of 400 ms followed by a S2 of 300, 250 and 200 ms provided from the left and right atrial appendage (LAA/RAA). Electrophysiological features included unipolar voltage, conduction velocity, potential type (single, short/long double and fractionated) and conduction delay/block (CDCB). Features of the shortest captured S2 were compared to the S1 sequence.ResultsThe average cycle length during SR was 962 [869–1085] ms. Compared to SR, during S1 pacing from both the RAA and LAA, voltage (RAA: -0.49 [-1.25–0.06] mV; LAA: -0.17 [-0.97–0.42] mV, P<0.001) and conduction velocity (RAA: -2.72 [-6.85–0.36] cm/s; LAA: -1.28 [-12.37–0.85] cm/s, P<0.001) decreased, and the amount of fractionation increased. In addition, CDCB increased specifically during RAA S1 pacing (+1.8 [0.1–3.2]%, P<0.001), while total activation time increased during LAA pacing (+16 [-1–29] ms, P<0.001). Applying the maximal captured S2, 12 patients had a refractory period of 250 ms, 13 patients of 200 ms and 3 patients <200 ms. In 4 patients, AF was induced by a S2 of 250 or 200 ms from either RAA or LAA. During both RAA and LAA S2 pacing, voltage (RAA: -1.33 [-2.51–-0.64] mV; LAA: -0.91 [-1.64–-0.46] mV, P<0.001) and conduction velocity (RAA: -16.34 [-24.49–-6.70] cm/s; LAA: -8.63 [-19.95–-1.25] cm/s, P<0.001) decreased, while total activation time (RAA: +26 [11–59] ms; LAA: +21 [2–46] ms, P<0.001) and CDCB (RAA: +5.7 [3.5–11.7] %; LAA: +4.1 [0.4–6.5] %, P<0.001) increased. Specifically, the average length of CDCB lines increased remarkably during LAA S2 pacing (+22 [8–39] mm, P<0.001) and even more during RAA S2 pacing (+36 [19–80] mm, P<0.001).ConclusionsPremature AES affect interatrial conduction via BB by enhancing conduction disorders. This indicates that BB is involved in AF initiation by ectopic beats, independently of their origin from the right or left atrium.

Decreased left atrial appendage function is an important predictor of elevated left ventricular filling pressure in patients with congestive heart failure

Direct Observation in Medical Education: A Review of the Literature and Evidence for Validity

Bachmann’s bundle (BB), also known as the interatrial bundle, is well recognized as a muscular bundle comprising of parallel aligned myocardial strands connecting the right and left atrial walls and is considered to be the main pathway of interatrial conduction.1 Disruption of the bundle’s structure causes interatrial conduction block (IAB),2 which is associated with development of various atrial tachyarrhythmias3,4 and with electromechanical dysfunction of the left atrium.5 Technological progress providing sophisticated mapping and imaging techniques in the past decade has increased our knowledge of specific anatomic structures and their role in development of both atrial brady- and tachyarrhythmias. This review outlines the current knowledge of the relation between anatomic and electrophysiological properties of BB and its possible role in initiation and perpetuation of atrial fibrillation (AF). In 1963, Thomas N. James described 3 pathways connecting the sinus node to the atrioventricular node (AVN), namely the anterior, medial, and posterior internodal pathways.6 Whether these conduction pathways were because of the presence of specialized conduction tissue or because of the anisotropic orientation of the muscle fibers remains controversial. Nevertheless, James described the anterior pathway as leaving the sinus node in anterior direction and giving off a secondary branch at the level of the superior vena cava to form BB.1 BB stretches subepicardially across the interatrial groove (septal raphe). It is at the interatrial groove that the BB can be identified as a discrete bundle (Figures 1 and 2) separated by fatty tissues from the infolded right atrial wall that is the limbus of the oval fossa. Notably, the bundle is not surrounded by a fibrous tissue sheath. Instead, the bundle is comprised of strands of atrial myocardium that are similarly aligned in parallel fashion. Its rightward and leftward extensions bifurcate to pass to either …

The study aimed to assess the impact of percutaneous transcatheter atrial septal defect (ASD) closure on atrium and atrial appandage functions among patients with ostium secundum ASDs. A total of 101 patients (34,7% male, 65,3% female, 37,6 ± 12) with the diagnosis of ostium secundum type ASD underwent transthorasic (TTE) and transesophageal echocardiography (TEE) before and six months after percutaneous transcatheter ASD closure. Pulmonary venous flow and atrial appendage flow velocities were obtained from the TEE recordings. The offline evaluation of the global and segmental atrial appendage strains were evaluated with speckle tracking echocardiography (STE) via EchoPac 6,3 (GE Vingmed, Horten, Norway). Mean values of pulmonary artery pressure, right ventricular, left atrium, left ventricular end-diastolic and end-systolic diameters were significantly decreased 6 months after ASD closure. Statistically significant changes were documented in pulmonary venous and left atrial appendage flow velocities after ASD closure. Both left and right atrial appendage flow velocities and global strains of atrial appandages were improved after ASD closure. The mean left atrial appendage global strain value was - 11.45 ± 4.13% before the procedure, this value was - 16.82 ± 3.78% sixth months after the procedure (P < 0.001).The mean right atrial appendage global strain was - 13.31 ± 4.84% before the procedure and - 18.53 ± 4.69% sixth months after the procedure (P < 0.001). Left and right atrial appendage flow velocities and global strains of left and right atrial appandage can be improved after transcatheter ASD closure. Percutaneous transcatheter closure of ASDs not only improves atrial and left ventricular dimensions but also have a positive impact on left and right atrial appandage functions.

Background: Cardioversion (CV) for persistent atrial fibrillation (PeAF) restores sinus rhythm (SR) but its effects on left atrial (LA) and LA appendage (LAA) flow are not well established. Research question: Does restoring sinus rhythm improve LA/LAA hemodynamics in patients with PeAF? Aims: To compare changes in LA/LAA 4D flow MRI characteristics post-CV for PeAF versus repeated measurements in a control group without AF. Methods: We performed 4D flow MRI (3T Skyra) in 9 PeAF patients (8 males, age 68±8 yrs, 78% HTN, 44% DM, 22% CAD, CHA2DS2-VASc 2.7±1.5, LVEF 53±17%) prior to and 62±44 days after CV (in SR) (minimum 4 weeks after CV). We also performed repeat MRIs in 9 SR controls (6 males, age 51±11 yrs, 78% HTN, 22% DM, 11% CAD, CHA2DS2-VASc 1.6±0.9, LVEF 62±4%) 60±19 days apart, both in SR (minimum 4 weeks apart). Data analysis included 3D segmentation of LA and LAA for evaluation of atrial velocity data. Absolute atrial velocities were calculated for each voxel and time frame inside the LA and LAA, and used to derive blood stasis (quantified by determining number of cardiac time frames with velocities below a threshold of 20 cm/s, normalized by the total number of cardiac time frames: Stasis%= (Nstasis/ NTotal)*100 ) and median velocity. Results: In PeAF, restoring SR improved 4D flow characteristics by reducing stasis and increasing median velocity (p&lt;0.003, figure). In the controls, there was no significant change in median velocity or stasis % between the two scans in either the LA or LAA. Bland-Altman analysis for the two control scans showed no significant differences in the controls. Pre-CV median velocities and stasis% in PeAF significantly differed from controls while post-CV, they did not. Conclusion: AF is associated with impaired LA and LAA flow characteristics that improve substantially with CV toward control values. Use of 4D MRI to quantify LA and LAA hemodynamic function is feasible; future studies are needed to correlate 4D MRI measurements to thromboembolic risk.

State University of New York Upstate Medical University College of Medicine

Context Bibliometric analysis is a method for analyzing the existing literature of a specific research area. Because it provides information about current research trends, the analysis can highlight attributes of frequently cited articles and identify areas for future research. To our knowledge, no such investigation has been conducted for osteopathic medical education. Objective To conduct a bibliometric analysis of the 100 top-cited articles in osteopathic medical education to identify characteristics of the articles and to explore the thematic structure and connections among common topics. Methods In October 2020, the Web of Science (WOS) Core Collection was searched for osteopathic medical education articles authored by faculty associated with U.S. colleges of osteopathic medicine (COMs). Search results included articles from 1975 to the present, based on the available dates of the indexes. Only articles in English were included in the search. Articles were identified using a three-stage search strategy and group consensus. Once identified, the following bibliometric characteristics were collected: journal name, journal impact factor, year of publication, article title, medical education research topic, authors, number of citations, and the authors’ COM affiliation. Articles were then hand searched in several non-indexed osteopathic-related journals, collecting the same data and using Google Scholar for the number of citations. The 100 top-cited articles were extracted and included in our analysis. Bibliometric metrics were calculated and summarized to assess performance and impact. Science mapping by topics was conducted to assess article contents. Specifically, network analysis and clustering were used to explore the structure and relationship of topics covered in the articles. Results Our WOS search identified 193,381 records. The highest 50,000 top-cited results were downloaded for screening, and an additional 89 records were identified from journal website searches. After initial screening and removal of duplicates, the title and abstract of 134 records were independently screened by each team member. Of those, 28 were excluded because they were not a U.S. study, authored by a non-COM author, or outside our study scope; six did not meet our exclusion criteria. The top-cited article was a systematic review that was cited 107 times. The journal with the most top-cited articles (28) was Academic Medicine, but BMC Medical Education had the highest number of citations per article (37.8). The Philadelphia College of Osteopathic Medicine and Ohio University Heritage College of Osteopathic Medicine tied for the highest number (15) of top-cited articles, but Lake Erie College of Osteopathic Medicine had the highest number of citations per article (39.8). Network analysis and clustering identified four thematic groupings: humanistic and whole-person care; clinical science and training; educational technology; and health-care systems. The topics within each cluster were cohesive, yet clusters also communicated with each other. Conclusion Results of the current study provided valuable information about the most frequent osteopathic medical education topics published by authors affiliated with COMs and suggested that journal impact factor was not a direct contributor to number of citations per article. The cluster analysis also provided insight about interconnected topics in osteopathic medical education. Results from this bibliometric analysis may be useful to inform future research, encourage collaboration, and provide guidance for advancing osteopathic medical education research in the United States.

To the Editor: With great interest we read the article by Onalan et al about left atrial appendage (LAA) exclusion for stroke prevention in nonrheumatic atrial fibrillation (AF).1 We share the author’s concerns about the hazards of this procedure and would like to emphasize additional arguments. There is no evidence that thromboembolism in AF exclusively derives from LAA thrombi detected by transesophageal echocardiography. The prevalences (4% to 21%) of LAA-thrombi were found in studies of acutely sick patients, patients before cardioversion, cardiac surgery or after recent embolism. Contrarily, when prospectively investigating clinically stable outpatients with AF and no recent embolism by transesophageal echocardiography, the prevalence of LAA thrombi was only …

Objective To study the left atrial appendage (LAA) function and haemodynamics by transesophageal echocardiography,and predict high risk of thrombosis.Methods Eighty-nine consecutive patients were studied using transesophageal echocardiography.According to with spontaneous echo contrast (SEC) or not,all patients were divided into SEC group (n =17) and non-SEC group (n-=72).LAA emptying peak flow velocity (LAA-EV),filling peak flow velocity (LAA-FV) were measured by pulsed Doppler.The middle segment of the LAA medial wall systolic peak velocity (LAA-TSV) and diastolic peak velocity (LAA-TDV) were obtained by tissue Doppler imaging.LAA color Doppler and M-mode color Doppler images were acquired and derived the LAA emptying flow propagation velocity (LAA-EPV).Results LAA-EV,LAA-FV,LAA-TSV,LAA-TDV,LAA-EPV of SEC group were lower than those of non-SEC group (P ＜0.05).LAA M-mode color Doppler had four characteristic patterns,N pattern (normal pattern) which flow eject from LAA apical to LAA orifice,R pattern (reverse pattern) which flow eject from LAA orifice to LAA apical,V pattern (vertical pattern) vertical signals seen in systole and without efficient flow,S pattern (stasis pattern) almost no flow signal.V,R and S patterns may indicate high risk of SEC and thrombosis.LAA-EPV had strong correlation with LAA-EV (r =0.742,P ＜0.001),and moderate correlation with LAA-TSV (r =0.462,P ＜0.01),LAA-EV had strong correlation with LAA-TSV (r =0.600,P ＜0.01).Conclusions LAA dysfunction would result in hypokinetic LAA wall motion and reduced blood flow velocity.Emptying abnormalities of LAA might be the important reasons for blood stasis and thrombus formation.Emptying characteristic low patterns of V,R and S might be novel methods to predict high risk of thrombus. Key words: Echocardiography,transesphageal; Atrial appendage; Hemodynamics

Introduction: Atrial appendages are recognised as structures with implications in cardiac thromboembolism and arrhythmogenesis. Variations in the shape and size of atrial appendages, especially the Left Atrial Appendage (LAA), have been found to impact these pathological conditions. Knowledge about the variations in the relationship of the LAA to its nearby structures is important in planning interventional and surgical procedures in and around the LAA. Most of the studies on variations in LAA morphology are image-based, with only a few anatomical studies available. Aim: To investigate the variations in the shape and size of the LAA using autopsy specimens. Materials and Methods: This cross-sectional study examined LAA specimens from 50 autopsies conducted in a tertiary care teaching hospital. Observations were made on the shape of LAA, the shape of LAA orifice, and its relationship with the Pulmonary Vein (PV) orifice. Measurements were taken of the LAA’s length, external diameter, and LAA orifice’s diameter. Endocasts were prepared from 30 specimens to estimate internal volume. The shape classification system proposed by Wang Y et al., was used. Categorical variables were expressed as percentages, and continuous variables as mean and standard deviation. Results: The windsock type was the most common seen in 29 (58%), followed by the chicken wing type in 15 (30%). The majority 30 (60%) of LAA orifices were oval. In 27 cases (54%), the Left Superior Pulmonary Vein (LSPV) orifice was at a higher level than LAA orifice and in 20 (40%), both orifices were at same level, with a prominent ridge between the orifices in all patients. The majority of appendages were bilobed 22 (44%). There was considerable variation in the length, diameter, and internal volume of the LAA appendage. Specimens from females were found to have smaller external diameters. One patient with an accessory LAA was identified. Conclusion: The shape variations observed in this study were similar to findings in some earlier studies but in contrast to others. Variations in the shape and size of the LAA orifice and the size of the LAA were consistent with those reported in earlier studies. Larger studies exploring these anatomical variations in specimens will be valuable for designing and developing therapeutic interventions in and around the LAA.

Article Title: Optimization of ASD Assessment Using Real Time Three‐Dimensional Transesophageal Echocardiography

Article Title: Observer Variation in the Echocardiographic Measurement of Maximum Atrial Septal Excursion: A Comparison of M‐Mode with Two‐Dimensional or Transesophageal Echocardiography(ECHOCARDIOGRAPHY, Volume 26, November 2009)

Article Title: Color M‐Mode Echocardiography is More Reproducible than Conventional M‐Mode Echocardiography for Septal‐to‐Posterior Wall Motion Delay Measurements.

Article Title: The Work‐Up and Management of Patients with Apparent or Subclinical Cardiac Sarcoidosis: With Emphasis on the Associated Heart Rhythm Abnormalities.