The Contractile Machines of the Heart.

This chapter will describe basic structural and functional features of the contractile apparatus of muscle cells of the heart, namely, cardiomyocytes and smooth muscle cells. Cardiomyocytes form the contractile myocardium of the heart, while smooth muscle cells form the contractile coronary vessels. Both muscle types have distinct properties and will be considered with respect to their cellular appearance (brick-like cross-striated versus spindle-like smooth), arrangement of contractile proteins (sarcomeric versus non-sarcomeric organization), calcium activation mechanisms (thin-filament versus thick-filament regulation), contractile features (fast and phasic versus slow and tonic), energy metabolism (high oxygen versus low oxygen demand), molecular motors (type II myosin isoenzymes with high adenosine diphosphate [ADP]-release rate versus myosin isoenzymes with low ADP-release rates), chemomechanical energy conversion (high adenosine triphosphate [ATP] consumption and short duty ratio versus low ATP consumption and high duty ratio of myosin II cross-bridges [XBs]), and excitation-contraction coupling (calcium-induced calcium release versus pharmacomechanical coupling). Part of the work has been published (Neuroscience - From Molecules to Behavior", Chap. 22, Galizia and Lledo eds 2013, Springer-Verlag; with kind permission from Springer Science + Business Media).

The right ventricle outflow tract systolic function could predict the severity of the cirrhosis.

Background/aim: The distinctive liver framework is converted into structurally abnormal nodules as a consequence of tissue fibrosis in cirrhosis. Cardiac dysfunction in cirrhosis was described, and the term "cirrhotic cardiomyopathy (CCM)" was coined to describe this syndrome. Recent research has shown that the contractile characteristics of the right ventricular outflow tract (RVOT) have a significant impact on right ventricular functions. The right ventricular outflow tract-systolic excursion is an important systolic function marker of RVOT (RVOT-SE). There has yet to be published research on RVOT function in cirrhotic patients. We looked at the relationship between cirrhosis severity and the RVOT-SE. Materials and methods: Sixty-nine consecutive hepatic cirrhotic patients were recruited for the research between June 1, 2018 and January 1, 2022. A medical history, thorough physical examination, laboratory investigations, echocardiographic evaluation, and RVOT-SE were obtained. The patients were separated into two groups: those with compensated cirrhosis (Child-Pugh class 1) and those with decompensated cirrhosis (Child-Pugh class 2 and 3). Results: On the numerous standard echocardiographic parameters that examined the diameter and function of the left ventricle, we observed no significant difference between groups. Nevertheless, a statistically significant difference in Right Ventricle Wall (RVW) (p = 0.014), systolic pulmonary artery pressure (sPAP) (p = 0.034), RVOT-SE (p = 0.003), and Tricuspid Annular Plane Systolic Excursion (TAPSE) (p = 0.042) was detected across cirrhosis groups. The RVOT-SE had a positive correlation with cirrhosis severity (OR: 0.607; 95% CI: 0.425-0.866; p = 0.006), according to multiple logistic regression studies. According to the ROC curve study, RVOT-SE 8.8 cm/s predicted decompensated cirrhosis with 72% sensitivity and 72.7% specificity (AUC = 0.715, p: 0.001). Conclusion: In the current study, we found that RVOT-SE was related to the severity of cirrhosis. Larger patient cohorts and multi-center investigations will provide light on the notion.

The influence of the cardiac cycle on the halo sign and its impact on the ultrasound diagnosis of giant cell arteritis.

OBJECTIVES: To investigate whether hypoechoic wall thickness is influenced by the systole or diastole moment in the cardiac cycle and if this can influence ultrasound (US) assessments of giant cell arteritis (GCA). METHODS: US videos of 100 consecutive patients (50 with GCA, 50 without) performed between January 2021 and June 2023 were reviewed. Intima-media thickness (IMT) of temporal (including common trunk, frontal and parietal branches), axillary and subclavian arteries were measured at two different time points, at systolic peak (SP) and at the end-diastole (ED). Differences between SP IMT and ED IMT, as well as in the halo count (HC) and in the OMERACT GCA Ultrasonography Score (OGUS) between these two times, were analyzed. RESULTS: IMT was significantly higher (4.8-5%) at ED in all arteries, in both GCA and non-GCA groups. HC and OGUS were also higher in ED in both groups. In 4 non-GCA patients (8%), the HC was positive in ED and negative in SP; in all of them the HC in ED was 1. In the GCA group, the timing of the cardiac cycle did not influence the final US diagnosis; however, it did modify the HC in 14 patients (28%). CONCLUSION: IMT can fluctuate during the cardiac cycle, with higher measurements occurring at ED. This variability could potentially impact the accuracy of US diagnoses and assessments of GCA. If further research corroborates these findings, it may be imperative to revise the guidelines for employing US in diagnosing GCA in order to incorporate these nuanced aspects.

Rate of deterioration of umbilical artery Doppler indices in fetuses with severe early-onset fetal growth restriction.

BACKGROUND: Incorporation of umbilical artery Doppler in the surveillance of fetal growth restriction has been shown to reduce the risk of perinatal deaths. Systole/Diastole ratio, Pulsatility Index and Resistance Index are obtained upon Doppler interrogation of the umbilical artery however it is unknown which index predicts more advanced stages of placental deterioration. OBJECTIVE: This study aimed to examine risk factors for the development of absent or reversed end-diastolic velocity and the time intervals of deterioration from normal umbilical artery end-diastolic velocity (indicated by systole/diastole ratio, pulsatility index, or resistance index) to decreased and absent or reversed end-diastolic velocity in fetuses with early-onset severe fetal growth restriction. STUDY DESIGN: This was a retrospective cohort study performed from 2005 to 2020. All singleton pregnancies with severe (estimated fetal weight or abdominal circumference below the third percentile) and early-onset (diagnosed between 20 0/7 and 31 6/7 weeks of gestation) fetal growth restriction were included. Patients with fetal genetic or structural anomalies, suspected congenital infections, absent or reversed end-diastolic velocity at diagnosis, poor pregnancy dating, and absence of follow-up ultrasounds were excluded. Estimated fetal weight, abdominal circumference, and Doppler indices were reviewed longitudinally from diagnosis to delivery. To examine risk factors for absent or reversed end-diastolic velocity, we performed backward stepwise logistic regression and calculated odds ratios with 95% confidence intervals. Kaplan-Meier curves were compared using log-rank tests. RESULTS: A total of 985 patients met the inclusion criteria, and 79 (8%) progressed to absent or reversed end-diastolic velocity. Factors associated with development of absent or reversed end-diastolic velocity included gestational age at diagnosis (adjusted odds ratio, 4.88 [95% confidence interval, 2.55-9.37] at 20 0/7 to 23 6/7 weeks; adjusted odds ratio, 1.56 [95% confidence interval, 0.86-2.82] at 24 0/7 to 27 6/7 weeks compared with 28 0/7 to 31 6/7 weeks) and presence of chronic hypertension (adjusted odds ratio, 2.37 [95% confidence interval, 1.33-4.23]). Rates of progression from diagnosis of fetal growth restriction with normal umbilical artery Doppler to absent or reversed end-diastolic velocity were significant after 4 weeks from diagnosis (5.84% [95% confidence interval, 4.50-7.57]). Regarding the Doppler indices, the progression from normal values to abnormal indices was similar at 1 and 2 weeks. However, the rate of progression from normal to abnormal systole/diastole ratio compared with the rates of progression from normal to abnormal pulsatility index or resistance index was higher at 4 and 6 weeks. Deterioration from abnormal indices to absent or reversed end-diastolic velocity was shorter with abnormal resistance index and pulsatility index when compared with the systole/diastole ratio at 2, 4, and 6 weeks after diagnosis and at 6 weeks, respectively. CONCLUSION: Earlier gestational age at diagnosis and chronic hypertension are considered as risk factors for Doppler deterioration and development of absent or reversed end-diastolic velocity in the umbilical artery. With normal Doppler indices, significant deterioration and progression to absent or reversed end-diastolic velocity is unlikely until 4 weeks after diagnosis. Abnormal systole/diastole ratio seems to appear first. However, abnormal pulsatility index or resistance index was associated with absent or reversed end-diastolic velocity.

Effects of the cardiac cycle on auditory processing: A preregistered study on mismatch negativity.

The systolic and diastolic phases of the cardiac cycle are known to affect perception and cognition differently. Higher order processing tends to be facilitated at systole, whereas sensory processing of external stimuli tends to be impaired at systole compared to diastole. The current study aims to examine whether the cardiac cycle affects auditory deviance detection, as reflected in the mismatch negativity (MMN) of the event-related brain potential (ERP). We recorded the intensity deviance response to deviant tones (70 dB) presented among standard tones (60 or 80 dB, depending on blocks) and calculated the MMN by subtracting standard ERP waveforms from deviant ERP waveforms. We also assessed intensity-dependent N1 and P2 amplitude changes by subtracting ERPs elicited by soft standard tones (60 dB) from ERPs elicited by loud standard tones (80 dB). These subtraction methods were used to eliminate phase-locked cardiac-related electric artifacts that overlap auditory ERPs. The endogenous MMN was expected to be larger at systole, reflecting the facilitation of memory-based auditory deviance detection, whereas the exogenous N1 and P2 would be smaller at systole, reflecting impaired exteroceptive sensory processing. However, after the elimination of cardiac-related artifacts, there were no significant differences between systole and diastole in any ERP components. The intensity-dependent N1 and P2 amplitude changes were not obvious in either cardiac phase, probably because of the short interstimulus intervals. The lack of a cardiac phase effect on MMN amplitude suggests that preattentive auditory processing may not be affected by bodily signals from the heart.

Echocardiographic characterization of cardiac chambers and vasculatures in buffaloes (Bubalus bubalis) during diastolic and systolic phases.

Background: Ultrasonography had diagnostic importance in the evaluation of different diseases in buffaloes, including cardiovascular diseases. Aim: The current work describes the normal echocardiographic findings in healthy buffaloes, along with establishing reference values for echocardiographic dimensions for both sides of the heart, i.e., left and right ones. Methods: About 30 healthy adult buffaloes that belonged to private farms in Assiut, Egypt, were included in this study. Each animal underwent a complete clinical evaluation as well as hematological analyses, lipid profile indices, liver functions, cardio-thoracic radiography, and echocardiography to confirm no diseased conditions were detected. The study was conducted on healthy buffaloes (n = 30) in Assiut Governorate, Egypt. Results: The obtained results reported healthy buffaloes with normal clinical findings as well as indices of blood pictures and serum biochemicals that were within the reference intervals. Radiography revealed a free reticulum and a well-defined diaphragm. The heart was seen as a typical radio-opaque organ. Ultrasonographically, using grayscale B-mode and M-mode, the heart was commonly imaged from the left fourth intercostal space. Different echocardiographic views were described, including the four chamber view, i.e., right atrium (RA), right ventricle (RV), tricuspid valve (TCV), left atrium, left ventricle, mitral valve, and interventricular septum (IVS), and the right ventricular outflow tract, i.e., RA, TCV, RV, pulmonary artery (PA), and pulmonary valve. Cross sections in each of the apex and base of the heart were described. Echocardiographic dimensions during cardiac diastole and systole, including diameters and wall thickness of each of the atria and ventricles, were demonstrated. Interventricular septal thickness wall thickness as well as diameters of the aorta and PA, were stated. Conclusion: The work tried to put reference values on the normal echocardiographic dimensions using 2-D B-mode gray scale ultrasonography in healthy adult buffaloes. These echocardiographic reference dimensions with normal echocardiographic imaging will be very helpful in enhancing the diagnostic efficacy of ultrasounds for recognizing abnormal findings related to cardiac disorders.

Cardiac function and posttraumatic stress disorder: a review of the literature and case report. / Fonction cardiaque et trouble de stress post-traumatique : revue de la littérature et étude de cas.

INTRODUCTION: Posttraumatic stress disorder (PTSD) can induce an elevation in sympathetic tone; however, research pertaining to the cardiac cycle in patients with PTSD is limited. METHODS: A literature review was conducted with PubMed, MEDLINE and Web of Science. Articles discussing changes and associations in echocardiography and PTSD or related symptoms were synthesized for the current review. We have also included data from a case report of a male participant aged 33 years experiencing potentially psychologically traumatic events, who wore a noninvasive cardiac sensor to assess the timing intervals and contractility parameters of the cardiac cycle using seismocardiography. The intervals included systolic time, isovolumic contraction time (IVCT) and isovolumic relaxation time (IVRT). Calculations of systolic (IVCT/systole), diastolic (IVRT/systole) and myocardial [(IVCT+IVRT)/systole] performance indices were completed. RESULTS: The review identified 55 articles, 14 of which assessed cardiac function using echocardiography in patients with PTSD symptoms. Cardiac dysfunction varied across studies, with diastolic and systolic impairments found in patients with PTSD. Our case study showed that occupational stress elevated cardiac performance indices, suggesting increased ventricular stress and supporting results in the existing literature. CONCLUSIONS: The literature review results suggest that a controlled approach to assessing cardiac function in patients with PTSD is required. The case study results further suggest that acute bouts of stress can alter cardiac function, with potential for sustained occupational stress to induce changes in cardiac function. Cardiac monitoring can be used prospectively to identify changes induced by potentially psychologically traumatic event exposures that can lead to the development of PTSD symptoms.

Cerebral arterial flow dynamics during systole and diastole phases in young and older healthy adults.

BACKGROUND: Since arterial flow is the leading actor in neuro-fluids flow dynamics, it might be interesting to assess whether it is meaningful to study the arterial flow waveform in more detail and whether this provides new important information. Few studies have focused on determining the influence of heart rate variation over time on the arterial flow curve. Therefore, this study aimed to evaluate cerebral arterial flow waveforms at extracranial and intracranial compartments in young and elderly healthy adults, also considering systole and diastole phases. METHODS: Cine phase-contrast magnetic resonance imaging (CINE-PC MRI) was performed on twenty-eight healthy young volunteers (HYV) and twenty healthy elderly volunteers (HEV) to measure arterial blood flows at the extracranial and intracranial planes. A semi-automated protocol using MATLAB scripts was implemented to identify the main representative points in the arterial flow waveforms. Representative arterial profiles were estimated for each group. Moreover, the effects of age and sex on flow times, amplitude-related parameters, and parameters related to systole and diastole phases were evaluated at the extracranial and intracranial compartments. Student's t-test or Wilcoxon's test (depending on the normality of the distribution) was used to detect significant differences. RESULTS: In HYVs, significant differences were observed between extracranial and intracranial levels in parameters related to the AP1 amplitude. Besides the detected differences in pulsatility index (extracranial: 0.92 ± 0.20 vs. 1.28 ± 0.33; intracranial: 0.79 ± 0.15 vs. 1.14 ± 0.18, p < .001) and average flow (715 ± 136 vs. 607 ± 125 ml/min, p = .008) between HYV and HEV, differences in the amplitude value of the arterial flow profile feature points were also noted. Contrary to systole duration (HYV: 360 ± 29 ms; HEV: 364 ± 47 ms), diastole duration presented higher inter-individual variability in both populations (HYV: 472 ± 145 ms; HEV: 456 ± 106 ms). Our results also showed that, with age, it is mainly the diastolic phase that changes. Although no significant differences in duration were observed between the two populations, the mean flow value in the diastolic phase was significantly lower in HEV (extracranial: 628 ± 128 vs. 457 ± 111 ml/min; intracranial: 599 ± 121 vs. 473 ± 100 ml/min, p < .001). No significant differences were observed in the arterial flow parameters evaluated between females and males in either HYV or HEV. CONCLUSION: Our study provides a novel contribution on the influence of the cardiac cycle phases on cerebral arterial flow. The main contribution in this study concerns the identification of age-related alterations in cerebral blood flow, which occur mainly during the diastolic phase. Specifically, we observed that mean flow significantly decreases with age during diastole, whereas mean flow during systole is consistent.

Morphological Changes of Anomalous Coronary Arteries From the Aorta During the Cardiac Cycle Assessed by IVUS in Resting Conditions.

BACKGROUND: Anomalous aortic origin of coronary artery (AAOCA) with intramural segment is associated with risk of sudden cardiac death, probably related to a compressive mechanism exerted by the aorta. However, the intramural compression occurrence and magnitude during the cardiac cycle remain unknown. We hypothesized that (1) in end diastole, the intramural segment is narrower, more elliptic, and has greater resistance than extramural segment; (2) the intramural segment experiences a further compression in systole; and (3) morphometry and its systolic changes vary within different lumen cross-sections of the intramural segment. METHODS: Phasic changes of lumen cross-sectional coronary area, roundness (minimum/maximum lumen diameter), and hemodynamic resistance (Poiseuille law for noncircular sections) were derived from intravascular ultrasound pullbacks at rest for the ostial, distal intramural, and extramural segments. Data were obtained for 35 AAOCA (n=23 with intramural tract) after retrospective image-based gating and manual lumen segmentation. Differences between systolic and end-diastolic phases in each section, between sections of the same coronary, and between AAOCA with and without intramural tract were assessed by nonparametric statistical tests. RESULTS: In end diastole, both the ostial and distal intramural sections were more elliptical (P<0.001) than the reference extramural section and the correspondent sections in AAOCA without intramural segment. In systole, AAOCA with intramural segment showed a flattening at the ostium (-6.76% [10.82%]; P=0.024) and a flattening (-5.36% [16.56%]; P=0.011), a narrowing (-4.62% [11.38%]; P=0.020), and a resistance increase (15.61% [30.07%]; P=0.012) at the distal intramural section. No-intramural sections did not show morphological changes during the entire cardiac cycle. CONCLUSIONS: AAOCA with intramural segment has pathological segment-specific dynamic compression mainly in the systole under resting conditions. Studying AAOCA behavior with intravascular ultrasound during the cardiac cycle may help to evaluate and quantify the severity of the narrowing.

Peak exercise myocardial deformation indices during cardiopulmonary exercise testing are associated with exercise capacity and ventilatory efficiency in patients with dilated cardiomyopathy.

OBJECTIVE: Little is known about the exercise-induced changes in the multidimensional mechanical properties of the heart. We aimed to evaluate the myocardial deformation indices (MDI) at rest and their response at peak exercise during the same cardiopulmonary exercise testing (CPET) session, investigating their relationship to exercise capacity and ventilatory sufficiency in dilated cardiomyopathy (DCM) patients. METHODS: We evaluated left ventricular (LV) function using speckle tracking imaging (STI) at rest and peak exercise during the same CPET session in 57 idiopathic DCM patients in New York Heart Association (NYHA) I-II class [54 ± 12 years, 42 males, ejection fraction (EF) 33 ± 9%]. We measured global longitudinal strain (GLS), longitudinal strain rate at systole (LSRS) and diastole (LSRD), and circumferential strain rate (CircS). RESULTS: Resting GLS, LSRS, and LSRD were impaired compared with the predicted values but were improved at peak exercise (p < 0.001). All MDI at rest and/or at peak exercise were related to several CPET-derived parameters, including peak VO2, load, O2 pulse, and VE/VCO2 slope. Peak exercise LSRS > -1.10 sec-1 (AUC = 0.80, p < 0.001) and GLS > -13% (AUC = 0.81, p = 0.002) predicted impaired exercise capacity (peak VO2 < 20 ml/min/kg) and ventilatory inefficiency (VE/VCO2 slope>34). In multiple regression analysis, peak exercise LSRS and GLS were independently related to the peak VO2 (Beta = -0.39, p = 0.003) and VE/VCO2 slope (Beta = 0.35, p = 0.02), respectively. CONCLUSIONS: Peak exercise LSRS and GLS in NYHA I-II DCM patients subjected to CPET were associated with aerobic exercise capacity and ventilatory efficiency. Consequently, LSRS and GLS at peak exercise, through their association with CPET-derived CV risk indices, may underline the severity of heart failure and predict future CV events in this DCM population.

Interstitial Collagen Loss, Myocardial Remodeling, and Function in Primary Mitral Regurgitation.

Interstitial collagen loss and cardiomyocyte ultrastructural damage accounts for left ventricular (LV) sphericity and decrease in LV twist and circumferential strain. Normal LV diastolic function belies significantly abnormal left atrial (LA) function and early LV diastolic untwist rate. This underscores the complex interplay of LV and LA myocardial remodeling and function in the pathophysiology of primary mitral regurgitation. In this study, we connect LA function with LV systolic and diastolic myocardial remodeling and function using cardiac magnetic resonance tissue tagging in primary mitral regurgitation.

Maternal Left Ventricular Function in Uncomplicated Twin Pregnancies: A Speckle-Tracking Imaging Longitudinal Study.

OBJECTIVE: The knowledge of maternal cardiovascular hemodynamic adaptation in twin pregnancies is incomplete. We aimed to longitudinally investigate maternal left ventricular (LV) function in uncomplicated twin pregnancies. METHODS: 30 healthy and uncomplicated twin pregnant women and 30 controls with normal singleton pregnancies were prospectively enrolled to undergo transthoracic echocardiography at 10-15 week's gestation (w) (T1), 19-26 w (T2) and 30-38 w (T3). LV dimensions and volumes, as well as LV ejection fraction (LVEF), mass (LVM) and diastolic parameters (at transmitral pulsed wave Doppler and mitral annular plane tissue Doppler), were calculated. Speckle-tracking imaging was also applied to evaluate LV global longitudinal (GLS), radial and circumferential 2D strains. RESULTS: During twin pregnancy, maternal LV dimensions, volumes and LVM had an increasing trend from T1 to T3, similar to singletons, while LVEF remained stable. There was LV remodeling/hypertrophy in 50% of women at T2 and T3 in both groups. Diastolic function had a worsening trend from T1 to T3 with no differences between twins and singletons, except for higher LV filling pressure (i.e., E/E') at T2 in twins. Two-dimensional strains did not vary during gestation in either group, except for a linear trend to increase (i.e., worsen) GLS in singletons. Radial and circumferential 2D strains were impaired in about half of the women at each trimester, while GLS was altered in one-fourth/one-third of them in both groups. CONCLUSION: Maternal LV geometry, dimensions and function are significantly impaired during twin pregnancies, in particular in the second half of gestation, with no significant differences compared to singletons.

Maternal Right Ventricular and Left Atrial Function in Uncomplicated Twin Pregnancies: A Longitudinal Study.

Objective: The knowledge regarding maternal cardiovascular hemodynamic adaptation in twin pregnancies is incomplete. We performed a longitudinal investigation of maternal right ventricular (RV) and left atrial (LA) function in a cohort of uncomplicated twin pregnancies compared to singleton pregnancies. Study design: Healthy women with uncomplicated twin pregnancies were prospectively enrolled and assessed by transthoracic echocardiography at 10−15 weeks' (w) gestation (T1), 19-26 w gestation (T2), and 30−38 w gestation (T3). Subjects with uneventful singleton pregnancies were selected as controls at the same gestational ages. Cardiac findings were compared to those of women with uneventful singleton gestations. RV systolic and diastolic functions were assessed by conventional echocardiography (FAC, TAPSE, sPAP, E, A, DT) and tissue Doppler imaging (TDI) (E', A', S', IVA, IVCT, IVRT, ET, MPI), and LA dimensions were calculated. Speckle-tracking imaging was also applied to evaluate RV global longitudinal strain and LA 2D strains (at LV end-systole (LAS) and at atrial contraction (LAA)). Results: Overall, 30 uncomplicated twin and 30 uncomplicated singleton pregnancies were included. Regarding maternal RV function in twins, all the parameters (FAC, TAPSE, sPAP, E, A, E/A, DT, E/E', IVA, IVCT, MPI and 2D longitudinal strain) were almost stable throughout gestation, with the exception of the TDI findings (E' decreased from T1 to T3 (p = 0.03), while E'/A' increased from T1 to T2 and then decreased (p = 0.01); A' and basal S' increased (p = 0.04 and p = 0.03, respectively), while IVRT and ET significantly decreased (p = 0.009 and p = 0.007, respectively)). These findings were similar to those found for singleton pregnancies. LA dimensions significantly increased throughout gestation in both twins and singletons (p < 0.001), without intergroup difference. LA strains did not vary during either twin or singleton pregnancies, except for LAA in T1, which was higher among twins than among singletons. Conclusion: Maternal RV and LA function in uncomplicated twin pregnancies does not seem to undergo more significant changes than in singletons, being characterized by similar findings in RV systolic and diastolic functions, as well as LA dimensions and strains.

Multisensory integration of anticipated cardiac signals with visual targets affects their detection among multiple visual stimuli.

Many studies have elucidated the multisensory processing of different exteroceptive signals (e.g., auditory-visual stimuli), but less is known about the multisensory integration of interoceptive signals with exteroceptive information. Here, we investigated the perceptual outcomes and electrophysiological brain mechanisms of cardio-visual integration by using participants' electrocardiogram signals to control the color change of a visual target in dynamically changing displays. Reaction times increased when the target change coincided with strong cardiac signals concerning the state of cardiovascular arousal (i.e., presented at the end of ventricular systole), compared to when the target change occurred at a time when cardiac arousal was relatively low (i.e., presented at the end of ventricular diastole). Moreover, the concurrence of the target change and cardiac arousal signals modulated the event-related potentials and the beta power in an early period (~100 ms after stimulus onset), and decreased the N2pc and the beta lateralization in a later period (~200 ms after stimulus onset). Our results suggest that the multisensory integration of anticipated cardiac signals with a visual target negatively affects its detection among multiple visual stimuli, potentially by suppressing sensory processing and reducing attention toward the visual target. This finding highlights the role of cardiac information in visual processing and furthers our understanding of the brain dynamics underlying multisensory perception involving both interoception and exteroception.

Cardiac cycle timing and contractility following acute sport-related concussion.

Cardiac sequelae following sport-related concussion are not well understood. This study describes changes in the cardiac cycle timing intervals and contractility parameters during the acute phase of concussion. Twelve athletes (21 ± 2 years, height = 182 ± 9 cm, mass = 86 ± 15 kg, BMI = 26 ± 3 kg/m2) were assessed within 5 days of sustaining a diagnosed concussion against their own pre-season baseline. A non-invasive cardiac sensor (LLA RecordisTM) was used to record the cardiac cycle parameters of the heart for 1 minute during supine rest. Cardiac cycle timing intervals (Isovolumic relaxation and contraction time, Mitral valve open to E wave, Rapid ejection period, Atrial systole to mitral valve closure, Systole, and Diastole) and contractile forces (Twist force and Atrial systole: AS) were compared. Systolic time significantly decreased during acute concussion (p = 0.034). Magnitude of AS significantly increased during acute concussion (p = 0.013). These results imply that concussion can result in altered systolic function.

MicroRNA-34c-5p provokes isoprenaline-induced cardiac hypertrophy by modulating autophagy via targeting ATG4B.

Pathological cardiac hypertrophy serves as a significant foundation for cardiac dysfunction and heart failure. Recently, growing evidence has revealed that microRNAs (miRNAs) play multiple roles in biological processes and participate in cardiovascular diseases. In the present research, we investigate the impact of miRNA-34c-5p on cardiac hypertrophy and the mechanism involved. The expression of miR-34c-5p was proved to be elevated in heart tissues from isoprenaline (ISO)-infused mice. ISO also promoted miR-34c-5p level in primary cultures of neonatal rat cardiomyocytes (NRCMs). Transfection with miR-34c-5p mimic enhanced cell surface area and expression levels of foetal-type genes atrial natriuretic factor (Anf) and ß-myosin heavy chain (ß-Mhc) in NRCMs. In contrast, treatment with miR-34c-5p inhibitor attenuated ISO-induced hypertrophic responses. Enforced expression of miR-34c-5p by tail intravenous injection of its agomir led to cardiac dysfunction and hypertrophy in mice, whereas inhibiting miR-34c-5p by specific antagomir could protect the animals against ISO-triggered hypertrophic abnormalities. Mechanistically, miR-34c-5p suppressed autophagic flux in cardiomyocytes, which contributed to the development of hypertrophy. Furthermore, the autophagy-related gene 4B (ATG4B) was identified as a direct target of miR-34c-5p, and miR-34c-5p was certified to interact with 3' untranslated region of Atg4b mRNA by dual-luciferase reporter assay. miR-34c-5p reduced the expression of ATG4B, thereby resulting in decreased autophagy activity and induction of hypertrophy. Inhibition of miR-34c-5p abolished the detrimental effects of ISO by restoring ATG4B and increasing autophagy. In conclusion, our findings illuminate that miR-34c-5p participates in ISO-induced cardiac hypertrophy, at least partly through suppressing ATG4B and autophagy. It suggests that regulation of miR-34c-5p may offer a new way for handling hypertrophy-related cardiac dysfunction.

Nicotinamide Mononucleotide Alleviates Cardiomyopathy Phenotypes Caused by Short-Chain Enoyl-Coa Hydratase 1 Deficiency.

Short-chain enoyl-CoA hydratase 1 (ECHS1) deficiency plays a role in cardiomyopathy. Whether ECHS1 deficiency causes or is only associated with cardiomyopathy remains unclear. By using Echs1 heterogeneous knockout (Echs1 +/-) mice, we found that ECHS1 deficiency caused cardiac dysfunction, as evidenced by diffuse myocardial fibrosis and upregulated fibrosis-related genes. Mechanistically, ECHS1 interacts with the p300 nuclear localization sequence, preventing its nuclear translocation in fibroblasts. ECHS1 deficiency promotes p300 nuclear translocation, leading to increased H3K9 acetylation, a known risk factor for cardiomyopathy. Nicotinamide mononucleotide-mediated acetylation targeting suppressed ECHS1 deficiency-induced cardiomyopathy phenotypes in Echs1 +/- mice. Thus, enhancing p300-mediated H3K9ac is a potential interventional approach for preventing ECHS1 deficiency-induced cardiomyopathy.