Worsened Tricuspid Regurgitation Following Pericardiectomy for Constrictive Pericarditis

Background: Worsening tricuspid regurgitation (TR) severity may occur after pericardiectomy surgery for constrictive pericarditis patients; however, its mechanisms and predictors are not well established. We evaluated the clinical characteristics, associated factors, and outcomes of worsening TR after pericardiectomy. Methods: Consecutive patients undergoing pericardiectomy for constrictive pericarditis without tricuspid valve surgery and with pre- and postoperative echocardiography available during 2000 to 2017 were retrospectively studied. Clinical, imaging, hemodynamic, and mortality characteristics were analyzed by those with and without worsening TR by at least one grade. Results: Among 381 patients (age 61 [17] years, 318 [83.5%] male), 193 (50.7%) had worsening TR post-operatively, and 75 died during the 2.5 (5.4) years follow-up. In univariable analysis, worsening TR was associated with a history of congestive heart failure (47.2% versus 31.9%, P =0.003), increased left atrial volume indexed (23 versus 20 mL/m 2 , P =0.020), reduced right ventricular fractional area change (47% versus 54%, P <0.001), and worsening mitral regurgitation (39.7% versus 16.6%, P <0.001). Worsened TR had a trend toward reduced survival during follow-up (log-rank P =0.080), especially those with worsened TR but no recovery of TR grade on subsequent echocardiography within the first year compared with those without worsened TR (log-rank P =0.02). In multivariable analysis, right ventricular fractional area change, left atrial volume indexed, left ventricular mass indexed, pulmonary artery systolic pressure, and right atrial pressure/pulmonary capillary wedge pressure ratio were most associated with worsened TR, while blood urea nitrogen, hematocrit, lateral and medial e’ tissue Doppler and heart rate were most associated with mortality during follow-up. Conclusions: Worsening TR severity was prevalent after pericardiectomy and had a trend toward reduced survival, especially if TR severity did not recover on subsequent echocardiography. Presence of parameters associated with worsened TR and reduced survival should alert clinicians to carefully manage these patients during follow-up.

Long-Term Electrocardiographic and Echocardiographic Progression of Arrhythmogenic Right Ventricular Cardiomyopathy and Their Correlation With Ventricular Tachyarrhythmias

Background: Prior studies of structural and electrocardiographic changes in arrhythmogenic right ventricular (RV) cardiomyopathy and their role in predicting ventricular arrhythmias (ventricular tachycardia) have shown conflicting results. Methods: We reviewed 405 ECGs, 315 transthoracic echocardiographies, and 441 implantable cardioverter defibrillator interrogations in 64 arrhythmogenic RV cardiomyopathy patients (56% men, mean age [SD], 44.2 [14.6] years) over a mean follow-up of 10 (range, 2.3–19) years. Generalized estimating equations were used to identify the association between ECG abnormalities, clinical variables, and transthoracic echocardiographic measurements (>mild degree of tricuspid regurgitation, RV outflow tract diameter in parasternal long axis and short axis, RV end-diastolic area, fractional area change). Results: There was a 4.65 (95% CI, 0.51%–8.8%) increase in RV end-diastolic area, a 3.75 (95% CI, 1.17%–6.34%) decrease in fractional area change, and 1.9 (95% CI, 1.3–2.8) higher odds (odds ratio) of RV wall motion abnormality with every 5-year increase in age after patients’ first transthoracic echocardiography. >Mild tricuspid regurgitation was an independent predictor of RV enlargement and dysfunction (hazard ratio of >10% drop in fractional area change from baseline [95% CI], 3.51 [1.77–6.95] and hazard ratio of >10% increase in RV end-diastolic area from baseline [95% CI], 4.90 [2.52–9.52]). Patients with implantable cardioverter defibrillator were more likely to develop >mild tricuspid regurgitation and larger structural and functional disease progression. More pronounced increase in RV end-diastolic area was translated into higher rates of any ventricular tachycardia. Inferior T-wave inversions and sum of R waves (mm) in V1 to V3 were predictors of RV enlargement and dysfunction with the former also predicting risk of any ventricular tachycardia. Conclusions: Arrhythmogenic RV cardiomyopathy is a progressive disease. Tricuspid regurgitation is an independent predictor of structural disease progression, which may be exacerbated by use of a transvenous implantable cardioverter defibrillator lead.

Defining the reference range for right ventricular systolic strain by echocardiography in healthy subjects: A meta-analysis

Background Right ventricular (RV) systolic strain has recently demonstrated prognostic value in various cardiovascular diseases. Despite this, the reference range including the lower limit of normal (LLN) and factors associated with RV strain measurements are not well-established. This meta-analysis aimed to determine the mean and LLN of two- (2D) and three-dimensional (3D) right ventricular global (RVGLS), free wall (RVFWLS) and interventricular septal wall (IVSLS) longitudinal strains in healthy individuals and factors that affect strain measurements. Methods In this meta-analysis, Pubmed, Embase and Cochrane databases were searched until 31 July 2020 for eligible studies reporting RVGLS, RVFWLS and/or IVSLS in at least 30 healthy subjects. We pooled the means and LLNs of RV strains by two- (2D) and three- (3D) dimensional echocardiography, and performed meta-regression analyses. Results From 788 articles screened, 45 eligible studies totaling 4439 healthy subjects were eligible for analysis. Pooled means and LLNs with 95% confidence intervals for 2D- RV strains were RVGLS -23.4% (-24.2%, -22.6%) and -16.4% (-17.3%, -15.5%) in 27 studies; RVFWLS -26.9% (-28.0%, -25.9%) and -18.0% (-19.2%, -16.9%) in 32 studies; and IVSLS –20.4% (-22.0%, -18.9%) and -11.5% (-13.6%, -9.6%) in 10 studies, and similar results for 3D- RV strains. Right ventricular fractional area change and vendor software were associated with 2D-RVGLS and RVFWLS means and LLNs. Conclusion We reported the pooled means and LLNs of RV systolic strains in healthy subjects, to define thresholds for abnormal, borderline and normal strains. Important factors associated with RV systolic strains include right ventricular fractional area change and vendor software.

A 1-Month Ketogenic Diet Increased Mitochondrial Mass in Red Gastrocnemius Muscle, but not in the Brain or Liver of Middle-Aged Mice

Alterations in markers of mitochondrial content with ketogenic diets (KD) have been reported in tissues of rodents, but morphological quantification of mitochondrial mass using transmission electron microscopy (TEM), the gold standard for mitochondrial quantification, is needed to further validate these findings and look at specific regions of interest within a tissue. In this study, red gastrocnemius muscle, the prefrontal cortex, the hippocampus, and the liver left lobe were used to investigate the impact of a 1-month KD on mitochondrial content in healthy middle-aged mice. The results showed that in red gastrocnemius muscle, the fractional area of both subsarcolemmal (SSM) and intermyofibrillar (IMM) mitochondria was increased, and this was driven by an increase in the number of mitochondria. Mitochondrial fractional area or number was not altered in the liver, prefrontal cortex, or hippocampus following 1 month of a KD. These results demonstrate tissue-specific changes in mitochondrial mass with a short-term KD and highlight the need to study different muscle groups or tissue regions with TEM to thoroughly determine the effects of a KD on mitochondrial mass.

Acute Exercise-Induced Changes in Cardiac Function Relates to Right Ventricular Remodeling Following 12-weeks Hypoxic Exercise Training

Repeated ventricular exposure to alterations in workload may relate to subsequent cardiac remodeling. We examined whether baseline acute changes in right (RV) and left ventricular (LV) function relate to chronic cardiac adaptation to 12-week exercise training. Twenty-one healthy individuals performed 12-week high-intensity endurance running training under hypoxia (fraction of inspired oxygen: 14.5%). Resting transthoracic echocardiography was performed before and after the training programme to assess ventricular structure, function and mechanics (including strain-area/volume loops). In addition, we examined systolic cardiac function during recumbent exercise under hypoxia at baseline (heart rate of 110-120 bpm, 'stress echocardiography'). Fifteen individuals completed training (22.0±2.4y, 10 male). Hypoxic exercise training increased RV size, including diameter and area (all p<0.05). With exception of an increase in RV fractional area change (p=0.03), RV function did not change post-training (all p>0.05). Regarding the RV strain-area loop, lower systolic and diastolic slopes were found post-training (p<0.05). No adaptation in LV structure, function or mechanics were observed (all p>0.05). To answer our primary aim, we found that a greater increase in RV fractional area change during baseline stress echocardiography (r=-0.67, P=0.01) inversely correlated with adaptation in RV basal diameter following 12-week training. In conclusion, 12-week high-intensity running hypoxic exercise training induced right-sided structural remodeling, which was, in part, related to baseline increase in RV fractional area change to acute exercise. These data suggest that acute cardiac responses to exercise may relate to subsequent RV remodeling after exercise training in healthy individuals.

Mental chronometry in big noisy data

Temporal measures (latencies) in the event-related potentials of the EEG (ERPs) are a valuable tool for mental chronometry. In large scale studies with a multitude of single EEG-based tasks the quality of latency measures often suffers from high and low frequency noise due to low trial counts (because of compressed tasks) and the missing opportunity of visual inspection. In the present study, we systematically evaluated two different approaches to latency estimation (peak latencies and fractional area latencies) with respect to their data quality and the application of noise reduction by jackknifing methods. Additionally, we tested the recently introduced method of Standardized Measurement Error (SME) to prune the dataset. We demonstrate that fractional area latency in pruned and jackknifed data may amplify within-subjects effect sizes by the factor ten in the analyzed data set. Between-subjects effects were less affected by the applied procedure, but remained stable regardless of procedure.

Comparison of semi-automated versus manual quantitative right ventricular assessment in tetralogy of Fallot

Background: Tetralogy of Fallot is a congenital heart defect diagnosed in infancy. Assessment of right ventricular size and function is important for evaluation of patients with tetralogy of Fallot, but these quantitative measures are challenging by echocardiography. This study evaluates a semi-automated software (EchoInsight®, Epsilon Imaging) by comparing its measures to manual measures in children with tetralogy of Fallot. Methods: Echocardiographic measurements were performed using manual techniques and semi-automated software. Right ventricular measurements included end-diastolic and end-systolic area, fractional area change, chamber dimensions, and tricuspid annular plane systolic excursion. Reliability, correlation, and agreement between manual and semi-automated measures were assessed. Results: Echocardiograms for 46 patients were analysed. Intra- and inter-observer reliabilities for semi-automated measures were good with intraclass correlation coefficients all over 0.95 and 0.85, respectively. There was high correlation between manual and semi-automated methods for areas and dimensions (r = 0.91–0.98). Tricuspid annular plane systolic excursion measures and fractional area change also correlated, albeit less strongly. The semi-automated measurements of end-systolic and end-diastolic area were a 20 and 47% higher than manual methods, respectively. The semi-automated method yielded a relative 52% lower fractional area change compared to the manual method. Conclusions: The semi-automated software generates quantitative right ventricular measures in children with tetralogy of Fallot with good reliability and good correlation with manual methods for all measures, but with significant difference between manual and semi-automated techniques for area and functional measures. The specific right ventricular geometry in tetralogy of Fallot children may be why, compared to normal anatomy, greater differences were observed between the two techniques.

Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates

Many glaciers are thinning rapidly beneath melt-reducing debris cover, including Kennicott Glacier in Alaska where glacier-wide maximum thinning also occurs under debris. This contradiction has been explained by melt hotspots, such as ice cliffs, scattered within the debris cover. However, melt hotspots alone cannot account for the rapid thinning at Kennicott Glacier. We consider the significance of ice cliffs, debris, and ice dynamics in addressing this outstanding problem. We collected abundant in situ measurements of debris thickness, sub-debris melt, and ice cliff backwasting, allowing for extrapolation across the debris-covered tongue (the study area and the lower 24.2 km2 of the 387 km2 glacier). A newly developed automatic ice cliff delineation method is the first to use only optical satellite imagery. The adaptive binary threshold method accurately estimates ice cliff coverage even where ice cliffs are small and debris color varies. Kennicott Glacier exhibits the highest fractional area of ice cliffs (11.7 %) documented to date. Ice cliffs contribute 26 % of total melt across the glacier tongue. Although the relative importance of ice cliffs to area-average melt is significant, the absolute area-averaged melt is dominated by debris. At Kennicott Glacier, glacier-wide melt rates are not maximized in the zone of maximum thinning. Declining ice discharge through time therefore explains the rapid thinning. There is more debris-covered ice in Alaska than in any other region on Earth. Through this study, Kennicott Glacier is the first glacier in Alaska, and the largest glacier globally, where melt across its debris-covered tongue has been rigorously quantified.

Abstract 12606: Meta-analysis of the Normal Ranges of Right Ventricular Strains by Echocardiography in Healthy Adults

Background: Right ventricular (RV) systolic strain has been increasingly shown to be prognostic in some cardiovascular diseases. Despite this, the reference range including the lower limit of normal (LLN) and factors associated with RV strain measurements are not well-established. This meta-analysis aimed to determine the means and LLNs of two- (2D) and three-dimensional (3D) right ventricular global (RVGLS), free wall (RVFWLS) and septal wall (RVSWLS) longitudinal strains in healthy individuals and factors affecting strain measurements. Methods: Pubmed, Embase and Cochrane databases were searched until 31 December 2019 for eligible studies reporting RVGLS, RVFWLS and/or RVSWLS in at least 30 healthy subjects. We pooled the means and LLNs of RV strains by two- (2D) and three- (3D) dimensional echocardiography, and performed meta-regression analyses. Results: From 591 articles screened, 37 eligible studies totaling 2970 subjects were analyzed. Pooled means and LLNs (95% confidence intervals) for 2D- strains were RVGLS -23.3% (-24.3%, -22.3%) and -16.2% (-17.2%, -15.1%) in 22 studies; RVFWLS -27.2% (-28.5%, -25.9%) and 18.5% (-20.0%, -17.1%) in 23 studies; RVSWLS -20.4% (-22.0%, -18.9%) and -11.5% (-13.6%, -9.6%) in 10 studies; and similar results for 3D- RV strains (Table). Right ventricular fractional area change and vendor software were associated with 2D-RVGLS and RVFWLS means and LLNs. Conclusion: We reported the pooled means and LLNs of RV systolic strains in healthy subjects, to define thresholds for abnormal, borderline and normal strains. Important factors associated with RV systolic strains include right ventricular fractional area change and vendor software.