Listen to your heart: Trade-off between cardiac interoceptive processing and visual exteroceptive processing.

Internal bodily signals, such as heartbeats, can influence conscious perception of external sensory information. Spontaneous shifts of attention between interoception and exteroception have been proposed as the underlying mechanism, but direct evidence is lacking. Here, we used steady-state visual evoked potential (SSVEP) frequency tagging to independently measure the neural processing of visual stimuli that were concurrently presented but varied in heartbeat coupling in healthy participants. Although heartbeat coupling was irrelevant to participants' task of detecting brief color changes, we found decreased SSVEPs for systole-coupled stimuli and increased SSVEPs for diastole-coupled stimuli, compared to non-coupled stimuli. These results suggest that attentional and representational resources allocated to visual stimuli vary according to fluctuations in cardiac-related signals across the cardiac cycle, reflecting spontaneous and immediate competition between cardiac-related signals and visual events. Furthermore, frequent coupling of visual stimuli with stronger cardiac-related signals not only led to a larger heartbeat evoked potential (HEP) but also resulted in a smaller color change evoked N2 component, with the increase in HEP amplitude associated with a decrease in N2 amplitude. These findings indicate an overall or longer-term increase in brain resources allocated to the internal domain at the expense of reduced resources available for the external domain. Our study highlights the dynamic reallocation of limited processing resources across the internal-external axis and supports the trade-off between interoception and exteroception.

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.

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.

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.

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.

Dual-phase imaging of cardiac metabolism using hyperpolarized pyruvate.

PURPOSE: Previous cardiac imaging studies using hyperpolarized (HP) [1-13 C]pyruvate were acquired at end-diastole (ED). Little is known about the interaction between cardiac cycle and metabolite content in the myocardium. In this study, we compared images of HP pyruvate and products at end-systole (ES) and ED. METHODS: A dual-phase 13 C MRI sequence was implemented to acquire two sequential HP images within a single cardiac cycle at ES and ED during successive R-R intervals in an interleaved manner. Each healthy volunteer (N = 3) received two injections of HP [1-13 C]pyruvate for the dual-phase imaging on the short-axis and the vertical long-axis planes. Spatial distribution of HP 13 C metabolites at each cardiac phase was correlated to multiphase 1 H MRI to confirm the mechanical changes. Ratios of myocardial HP metabolites were compared between ES and ED. Segmental analysis was performed on the midcavity short-axis plane. RESULTS: In addition to mechanical changes, metabolic profiles of the heart detected by HP [1-13 C]pyruvate differed between ES and ED. The myocardial signal of [13 C]bicarbonate relative to [1-13 C]lactate was significantly smaller at ED than the ratio at ES (p < .05), particularly in mid-anterior and mid-inferoseptal segments. The distinct metabolic profiles in the myocardium likely reflect the technical aspects of the imaging approach such as the coronary flow in addition to the cyclical changes in metabolism. CONCLUSION: The study demonstrates that metabolic profiles of the heart, measured by HP [1-13 C]pyruvate, are affected by the cardiac cycle in which that the data are acquired.

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.

Dose Escalation and Safety of Capsaicin for Cerebral Perfusion Augmentation: A Pilot Study.

Background and Purpose: Sphenopalatine ganglion (SPG) electrical stimulation has been studied in the setting of acute ischemic stroke to enhance collateral flow. Capsaicin poses an alternative to chemically stimulate the sphenopalatine ganglion. Therefore, the objective of this study was to determine the safety and effect of increasing doses of capsaicin upon serial transcranial Doppler markers of cerebral blood flow. Methods: We performed serial transcranial Doppler testing in 30 healthy volunteers divided into 5 equal groups. Capsaicin doses ranged from 33 to 165 µMol. We recorded peak systolic and end-diastolic velocities in the middle cerebral artery, arterial pressure, and perceived pungency in 5-minute intervals up to 20 minutes. We then calculated the mean velocity, the pulsatility index, and the cerebral blood flow index. Results: The participants' median age was 21 years (range, 5 years); all reported consumption of capsaicin in their diets. After and during the study, none reported side effects. Perceived pungency peaked at 5 minutes, and by the 20-minute mark, none perceived any pungency. All the tested doses produced the same pattern, consisting of augmentation of the middle cerebral artery mean velocity with the pulsatility index's diminution. The effects peaked between the 5- and the 10-minute measurements and then returned to basal levels except for the 66-µMol doses, which produced a sustained effect. We found no correlation between perceived pungency and dose, but the middle cerebral artery mean velocity was strongly correlated with the dose administered. Conclusions: This study provides evidence supporting the safety and tolerability of oral capsaicin in a population of healthy volunteers. Capsaicin appears to produce effects similar to those of sphenopalatine ganglion electrical stimulation. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04545892.

Body Mass Index and Arterial Stiffness Are Associated With Greater Beat-to-Beat Blood Pressure Variability After Transient Ischemic Attack or Minor Stroke.

[Figure: see text].

Oral contraceptives and hypertension in women: results of the enrolment phase of Tabari Cohort Study.

BACKGROUND: The association between oral contraceptives (OCP) and hypertension has been reported in the literature with controversial results. According to the growing use of OCPs among women in Iran, this study aims to investigate the association between the duration of the OCP consumption and risk of hypertension among Iranian women. METHODS: In the current study, the data collected during the enrolment phase of the Tabari cohort were analyzed. Of 6106 women recruited in the cohort, 133 pregnant women were excluded. Epidemiological variables were collected using pre-designed questionnaires as well as the health insurance evidences. In addition, blood pressure and anthropometric factors were measured based on the standard guidelines. Chi square and partial correlation tests as well as logistic regression models were applied for data analysis. RESULTS: Frequency of oral contraceptive use among 35-70 year-old women in Tabari cohort study (TCS) was 42.2% (2520/5973). Hypertension was observed among 25% (1793/5973) of them. The adjusted odds ratio for OCP use was 1.23 (95% confidence interval: 1.08, 1.40, p = 0.002). The corresponding odds ratios for 61-120 months and more than 120 months OCP use were 1.39 (1.12,1.73) and 1.47 (1.16,1.87) respectively. CONCLUSIONS: Oral contraceptives especially in long term use can be associated with hypertension.

Accurate end systole detection in dicrotic notch-less arterial pressure waveforms.

Identification of end systole is often necessary when studying events specific to systole or diastole, for example, models that estimate cardiac function and systolic time intervals like left ventricular ejection duration. In proximal arterial pressure waveforms, such as from the aorta, the dicrotic notch marks this transition from systole to diastole. However, distal arterial pressure measures are more common in a clinical setting, typically containing no dicrotic notch. This study defines a new end systole detection algorithm, for dicrotic notch-less arterial waveforms. The new algorithm utilises the beta distribution probability density function as a weighting function, which is adaptive based on previous heartbeats end systole locations. Its accuracy is compared with an existing end systole estimation method, on dicrotic notch-less distal pressure waveforms. Because there are no dicrotic notches defining end systole, validating which method performed better is more difficult. Thus, a validation method is developed using dicrotic notch locations from simultaneously measured aortic pressure, forward projected by pulse transit time (PTT) to the more distal pressure signal. Systolic durations, estimated by each of the end systole estimates, are then compared to the validation systolic duration provided by the PTT based end systole point. Data comes from ten pigs, across two protocols testing the algorithms under different hemodynamic states. The resulting mean difference ± limits of agreement between measured and estimated systolic duration, of [Formula: see text] versus [Formula: see text], for the new and existing algorithms respectively, indicate the new algorithms superiority.

Sex differences and the effects of intrauterine hypoxia on growth and in vivo heart function of fetal guinea pigs.

We hypothesized that the physiological adaptations of the fetus in response to chronic intrauterine hypoxia depend on its sex and the gestational age of exposure. Pregnant guinea pigs were exposed to room air (normoxia, NMX) or 10.5% O2 (hypoxia, HPX) at either 25 days (early onset) or 50 days (late onset) of gestation until term (~65 days). We evaluated the effects of HPX on hemodynamic and cardiac function indices using Doppler ultrasound and determined sex-related differences in near-term fetuses. Indices of uterine/umbilical artery pulsatility (PI index) and fetal heart systolic and diastolic function [Tei index and passive filling (E-wave) to filling due to atrial contraction (A-wave) (E/A ratios), respectively] were measured in utero and fetal body (FBW) and organ weights measured from extracted fetuses. Both early- and late-onset HPX decreased FBW in both males and females, had no effect on placenta weights, and increased placenta weight-to-FBW ratios. Early- but not late-onset HPX increased uterine artery PI, but neither HPX condition affected umbilical artery PI. Early-onset HPX increased left ventricle E/A ratios in both males and females, whereas late-onset HPX increased the right ventricle E/A ratio in females only. Hypoxia had no effect on the Tei index in either sex. Early- and late-onset HPX induce placental insufficiency and fetal growth restriction and increase diastolic filling depending on the sex, with female fetuses having a greater capacity than males to compensate for intrauterine hypoxia.

Load-independent effects of empagliflozin contribute to improved cardiac function in experimental heart failure with reduced ejection fraction.

BACKGROUND AND AIMS: Sodium-glucose linked cotransporter-2 (SGLT2) inhibitors reduce the likelihood of hospitalization for heart failure and cardiovascular death in both diabetic and non-diabetic individuals with reduced ejection fraction heart failure. Because SGLT2 inhibitors lead to volume contraction with reductions in both preload and afterload, these load-dependent factors are thought to be major contributors to the cardioprotective effects of the drug class. Beyond these effects, we hypothesized that SGLT2 inhibitors may also improve intrinsic cardiac function, independent of loading conditions. METHODS: Pressure-volume (P-V) relationship analysis was used to elucidate changes in intrinsic cardiac function, independent of alterations in loading conditions in animals with experimental myocardial infarction, a well-established model of HFrEF. Ten-week old, non-diabetic Fischer F344 rats underwent ligation of the left anterior descending (LAD) coronary artery to induce myocardial infarction (MI) of the left ventricle (LV). Following confirmation of infarct size with echocardiography 1-week post MI, animals were randomized to receive vehicle, or the SGLT2 inhibitor, empagliflozin. Cardiac function was assessed by conductance catheterization just prior to termination 6 weeks later. RESULTS: The circumferential extent of MI in animals that were subsequently randomized to vehicle or empagliflozin groups was similar. Empagliflozin did not affect fractional shortening (FS) as assessed by echocardiography. In contrast, load-insensitive measures of cardiac function were substantially improved with empagliflozin. Load-independent measures of cardiac contractility, preload recruitable stroke work (PRSW) and end-systolic pressure volume relationship (ESPVR) were higher in rats that had received empagliflozin. Consistent with enhanced cardiac performance in the heart failure setting, systolic blood pressure (SBP) was higher in rats that had received empagliflozin despite its diuretic effects. A trend to improved diastolic function, as evidenced by reduction in left ventricular end-diastolic pressure (LVEDP) was also seen with empagliflozin. MI animals treated with vehicle demonstrated myocyte hypertrophy, interstitial fibrosis and evidence for changes in key calcium handling proteins (all p < 0.05) that were not affected by empagliflozin therapy. CONCLUSION: Empagliflozin therapy improves cardiac function independent of loading conditions. These findings suggest that its salutary effects are, at least in part, due to actions beyond a direct effect of reduced preload and afterload.

Influence of contrast agent and spatial resolution on myocardial strain results using feature tracking MRI.

OBJECTIVES: Feature tracking for assessing myocardial strain from cardiac magnetic resonance (CMR) cine images detects myocardial deformation abnormalities with prognostic implication, e.g., in myocardial infarction and cardiomyopathy. Standards for image acquisition and processing are not yet available. Study aim was analyzing the influence of spatial resolution and contrast agent on myocardial strain results. METHODS: Seventy-five patients underwent CMR for analyzing peak systolic circumferential, longitudinal, and radial strain. Group A included n = 50 with normal left ventricular ejection fraction, no wall motion abnormality, and no fibrosis on late enhancement imaging. Group B included n = 25 with chronic myocardial infarct. For feature tracking, steady-state free precession cine images were acquired repeatedly. (1) Native standard cine (spatial resolution 1.4 × 1.4 × 8 mm3). (2) Native cine with lower spatial resolution (2.0 × 2.0 × 8 mm3). (3) Cine equal to variant 1 acquired after administration of gadoteracid. RESULTS: Lower spatial resolution was associated with elevated longitudinal strain (- 21.7% vs. - 19.8%; p < 0.001) in viable myocardium in group A, and with elevated longitudinal (- 17.0% vs. - 14.3%; p = 0.001), circumferential (- 18.6% vs. - 14.6%; p = 0.002), and radial strain (36.8% vs. 31.0%; p = 0.013) in infarcted myocardium in group B. Gadolinium administration was associated with reduced circumferential (- 21.4% vs. - 22.3%; p = 0.001) and radial strain (44.4% vs. 46.9%; p = 0.016) in group A, whereas strain results of the infarcted tissue in group B did not change after contrast agent administration. CONCLUSIONS: Variations in spatial resolution and the administration of contrast agent may influence myocardial strain results in viable and partly in infarcted myocardium. Standardized image acquisition seems important for CMR feature tracking. KEY POINTS: • Feature tracking is used for calculating myocardial strain from cardiac magnetic resonance (CMR) cine images. • This prospective study demonstrated that CMR strain results may be influenced by spatial resolution and by the administration of gadolinium-based contrast agent. • The results underline the need for standardized image acquisition for CMR strain analysis, with constant imaging parameters and without contrast agent.

Levosimendan or milrinone for right ventricular inotropic treatment?-A secondary analysis of a randomized trial.

BACKGROUND: The aim of the present study was to compare the effects of milrinone and levosimendan on right ventricular (RV) inotropy and lusitropy in patients after aortic valve replacement (AVR) for aortic stenosis, a procedure in which an abnormal postoperative RV function may be seen. METHODS: In a prospective, blinded trial, 31 patients were randomized to receive either milrinone (0.4 and 0.8 µg/kg/min, n = 16) or levosimendan (0.1 and 0.2 µg/kg/min, n = 15) after AVR for aortic stenosis. RV performance, afterload (pulmonary arterial elastance), RV strain, systolic (SR-S) and early diastolic (SR-E) strain rate were measured by pulmonary artery thermodilution catheterization and transoesophageal two-dimensional speckle tracking echocardiography. To circumvent the indirect effects of inodilator-induced hemodynamic changes on RV systolic and diastolic deformation, pulmonary arterial elastance, central venous pressure and heart rate were maintained constant by atrial pacing, plasma volume expansion with colloids and phenylephrine-induced vasoconstriction during treatment with the inotropes. RESULTS: A dose-dependent increase in stroke volume index and cardiac index by approximately 20% were seen with both agents at the highest doses, with no difference between groups (P = .792 and 0.744, respectively). In both groups, RV strain and SR-S dose-dependently increased by 20% and 15%-19%, respectively, at the highest doses (P = .742 and 0.259, respectively) with no difference between groups. SR-E improved by both agents 20%-24% at the highest dose with no difference between groups (P = .714). CONCLUSIONS: The direct RV inotropic and lusitropic effects of levosimendan and milrinone were comparable at clinically relevant infusion rates.

The value of bronchial and cavity contraction rates in differentiating benign and malignant pulmonary cavities.

BACKGROUND: The present study aimed to assess the value of bronchial and cavity contraction percentages in differentiating benign and malignant pulmonary cavities. METHODS: Forty-two patients with pulmonary cavities were scanned by dual-phase computed tomography (CT). Then, the cavity and bronchial contraction percentages were respectively measured, the differences between the benign and malignant cavities were compared, and the best diagnostic critical point for differentiating benign and malignant cavities was obtained through the receiver operator characteristic (ROC) curve of the diagnostic test. RESULTS: The contraction percentage of the bronchial end with benign cavities was significantly higher than that of the bronchial end with malignant cavities (P < 0.001). The contraction percentage was significantly higher in the benign group than in the malignant group (P < 0.001). The ROC analysis revealed that the sensitivity and specificity of the bronchial contraction percentage was 90.50 and 86.40%, respectively, while the sensitivity and specificity of the cavity contraction percentage was 90.50 and 90.90%, respectively. CONCLUSION: The dual-phase CT scanning of the bronchial and cavity contraction percentage can distinguish between benign and malignant cavities.

The impact of frame numbers on cardiac ECG-gated SPECT images with interpolated extra frames using echocardiography.

Background: Cardiac echocardiography and cardiac ECG-gated single-photon emission computed tomography (SPECT) are the most common modalities for left ventricle (LV) volumes and function assessment. The temporal resolution of SPECT images is limited and an ECG provides better temporal resolution. This study investigates the impact of frame numbers on images in terms of qualitative and quantitative assessments. Methods: In this study, 5 patients underwent echocardiography and cardiac ECG-gated SPECT imaging, and 5 standard views of the LV were recorded to determine LV walls boundaries and volumes. Also, 2 original images with 8 frames and 16 frames per cardiac cycle were recorded simultaneously in a single gantry orbit. Using the data extracted from the LV model, 8 extra new frames were created with interpolation between existing frames of the original 8-frame image. Three series of images (8 and 16 original and 16 interpolated) were reconstructed separately. LV volumes and ejection fraction (EF) were calculated using Quantitative Gated SPECT (QGS) software. Results: Compared to the original 8-frame gating, original 16-frame gated images resulted in larger end-diastole volume (EDV) (mean ± SD: 68.6 ± 27.11 mL vs 66.2±25.41 mL, p<0.001), smaller end-systole volume (ESV) (mean ± SD: 24.6±8.7 mL vs 26±7.3 mL, p<0.001), and higher EF (64% vs 60.2%, p<0.001). The results for the interpolated series were also different from the original images (closer to the original 16-frame series rather than 8-frame). Conclusion: Changing the frame number from 8 to 16 in cardiac ECG-gated SPECT images caused a significant change in LV volumes and EF. Frame interpolation with sophisticated algorithms can be used to improve the temporal resolution of SPECT images.

How myofilament strain and strain rate lead the dance of the cardiac cycle.

Movement of the myocardium can modify organ-level cardiac function and its molecular (crossbridge) mechanisms. This motion, which is defined by myocardial strain and strain rate (muscle shortening, lengthening, and the speed of these movements), occurs throughout the cardiac cycle, including during isovolumic periods. This review highlights how the left ventricular myocardium moves throughout the cardiac cycle, how muscle mechanics experiments provide insight into the regulation of forces used to move blood in and out of the left ventricle, and its impact on (and regulation by) crossbridge and sarcomere kinetics. We specifically highlight how muscle mechanics experiments explain how myocardial relaxation is accelerated by lengthening (strain rate) during late systole and isovolumic relaxation, a lengthening which has been measured in human hearts. Advancing and refining both in vivo measurement and ex vivo protocols with physiologic strain and strain rates could reveal important insights into molecular (crossbridge) kinetics. These advances could provide an improvement in both diagnosis and precise treatment of cardiac dysfunction.

Mitral annular peak systolic and diastolic velocities are characteristic of healthy hearts: A Doppler tissue imaging study.

INTRODUCTION: Although systolic and diastolic dysfunction must coexist, they are most often considered in isolation. Therefore, a simple and reproducible quantitative measurement that integrates systolic and diastolic function is desirable. We hypothesize that the absolute sum of lateral mitral annular systolic and early diastolic peak velocities is predictive of overall cardiac function. METHODS: In this study, lateral mitral annular systolic (S') and early diastolic (E') peak velocities were measured in healthy subjects and compared against subjects with progressive degrees of systolic and diastolic dysfunction. RESULTS: A total of 149 subjects (56% male, mean age 48 years) were enrolled and stratified according to global left ventricular function: 76 normal, 40 mild-moderate dysfunction, and 33 moderate-severe dysfunction. Adjusting for baseline differences including age, univariate analysis showed mean S' + E' values were significantly different between subjects with normal, mild-moderate, and moderate-severe global left ventricular function (27, 17, 13 cm/s; P < 0.001 for all comparisons). The absolute sum of S' + E' ≥ 20 cm/s identified normal global left ventricular function with a sensitivity of 95%, specificity of 85%, and ROC area under the curve of 0.924. CONCLUSIONS: In a cohort of subjects with varying levels of combined systolic and diastolic function, the easily obtainable composite score of S' + E' ≥ 20 cm/s is strongly predictive of normal global left ventricular function with a high degree of sensitivity and specificity. Additional studies should be considered to expand this concept to additional populations.