Heart Rate Control during Experimental Sepsis in Mice: Comparison of Ivabradine and β-Blockers

Evaluation of the efficacy of silymarin and dexmedetomidine on kidney and lung tissue in the treatment of sepsis in rats with cecal perforation

Sepsis is a systemic inflammatory response syndrome that develops in the host against microorganisms. This response develops away from the primary infection site and results in end-organ damage. The present study aimed to investigate the protective and therapeutic effects on lung and kidney tissue of silymarin (S) and dexmedetomidine (DEX) applied 1 h before and after sepsis induced by the cecal ligation and puncture (CLP) method in rats. A total of 62 rats was randomly divided into eight groups: i) Control (n=6); ii) cecal perforation (CLP; n=8); iii) S + CLP (n=8; S + CLP; S administered 1 h before CPL); iv) CLP + S (n=8; S administered 1 h after CLP); v) DEX + CLP (n=8; D + CLP; DEX administered 1 h before CLP); vi) CLP + D (n=8; DEX administered 1 h after CLP); vii) SD + CLP (n=8; S and DEX administered 1 h before CLP) and viii) CLP + SD (n=8; S and DEX administered 1 h after CLP). After the cecum filled with stool, it was tied with 3/0 silk under the ileocecal valve and the anterior surface of the cecum was punctured twice with an 18-gauge needle. A total of 100 mg/kg silymarin and 100 µg/kg DEX were administered intraperitoneally to the treatment groups. Lung and kidney tissue samples were collected to evaluate biochemical and histopathological parameters. In the histopathological examination, all parameters indicating kidney injury; interstitial edema, peritubular capillary dilatation, vacuolization, ablation of tubular epithelium from the basement membrane, loss of brush border in the proximal tubule epithelium, cell swelling and nuclear defragmentation; were increased in the CLP compared with the control group. Silymarin administration increased kidney damage, including ablation of tubular epithelium from the basement membrane, compared with that in the CLP group. DEX significantly reduced kidney damage compared with the CLP and silymarin groups. The co-administration of DEX + silymarin decreased kidney damage, although it was not as effective as DEX-alone. To conclude, intraperitoneal DEX ameliorated injury in CLP rats. DEX + silymarin partially ameliorated injury but silymarin administration increased damage. As a result, silymarin has a negative effects with this dosage and DEX has a protective effect. In the present study, it was determined that using the two drugs together had a greater therapeutic effect than silymarin and no differences in the effects were not observed any when the application times of the agents were changed.

Novel Use of Ivabradine for Persistent Sinus Tachycardia in a Patient on Extracorporeal Life Support With Right Ventricular Dysfunction

Persistent sinus tachycardia (pST) has been associated with adverse cardiovascular events in critically ill patients. Pharmacological control of heart rate with negative inotropic agents has proven to be safe but could be potentially dangerous in patients with concomitant right ventricular (RV) dysfunction. Ivabradine, a medication devoid of negative inotropy, could be a potentially safe solution for this patient population when adequate heart rate control is desired. A 17-year-old male with a history of vaping developed acute respiratory distress syndrome (ARDS) and RV dysfunction, requiring extra corporal life support (ECLS). He suffered from pST. Given his RV dysfunction, a beta-blocker was avoided, and ivabradine was used safely with improvement of his pST. This case demonstrates the efficacy of ivabradine to reduce heart rate and avoid the use of beta-blockers for patients with RV dysfunction, which could be detrimental. Ivabradine was shown to lower the heart rate without altering hemodynamic parameters.

Cardiac index and heart rate as prognostic indicators for mortality in septic shock: A retrospective cohort study from the MIMIC-IV database

Background

Septic shock is a life-threatening condition that can lead to organ dysfunction and death. In the ICU, monitoring of cardiac index (CI) and heart rate (HR) is commonly used to guide management and predict outcomes in septic shock patients. However, there is a lack of research on the association between CI and HR and the risk of mortality in this patient population. Therefore, the aim of this study was to investigate the relationship between different levels of CI and HR and mortality in septic shock patients.

Methods

Data analysis was obtained from the MIMIC-IV version 2.0 database. Sepsis and septic shock were primarily defined by sepsis-3, the third international consensus on sepsis and septic shock. CI was computed using cardiac output (CO) and body surface area (BSA). To evaluate the incidence of CI with respect to each endpoint (7-, 14-, 21-, and 28-day mortality), a restricted cubic spline curve function (RCS) was used. The optimal cutoff value for predicted mortality was determined using the Youden index. Analyses of KM curves, cox regression, and logistic regression were conducted separately to determine the relationship between various CI and HR and 28-day mortality.

Results

This study included 1498 patients with septic shock. A U-shaped relationship between CI levels and risk of mortality in septic shock was found by RCS analysis (p < 0.001). CI levels within the intermediate range of 1.85-2.8 L/min/m2 were associated with a mortality hazard ratio (HR) < 1. In contrast, low CI (HR = 1.87 95% CI: 1.01-3.49) and high CI (HR = 1.93 95% CI: 1.26-2.97) had a significantly increased risk of mortality. The AUC for heart rate prediction of mortality by Youden index analysis was 0.70 95%CI:0.64-0.76 with a cut-off value of 93.63 bpm. According to the characteristics of HR and CI, patients were divided into six subgroups HR↓+CI intermediate group (n = 772), HR↓+CI↓ group (n = 126), HR↓+CI↑ group (n = 294), HR↑+CI intermediate group (n = 132), HR↑+CI↓ group (n = 24), and HR↑+CI↑ group (n = 150). The KM curves, COX regression, and logistic regression analysis showed that the survival rates the of HR↓+CI intermediate group, HR↓+CI↓ group, and HR↓+CI↑ were higher than the other groups. The risk factors of HR↑+CI intermediate group, HR↑+CI↓, and HR↑+CI↑ with ICU 28-day mortality were HR = 2.91 (95% CI: 1.39-5.97), HR = 3.67 (95% CI: 1.39-11.63), and HR = 5.77 (95% CI: 2.98-11.28), respectively.

Conclusion

Our retrospective study shows that monitoring cardiac index and heart rate in patients with septic shock may help predict the organismal response and hemodynamic consequences, as well as the prognosis. Thus, healthcare providers should carefully monitor changes in these parameters in septic shock patients transferred to the ICU for treatment.

Clinical Implications of Ivabradine in the Contemporary Era

Ivabradine is a recently introduced inhibitor of the If ion channel, which exhibits the capacity to reduce heart rate while preserving hemodynamic stability. At present, ivabradine finds its clinical indication in patients suffering from heart failure with reduced ejection fraction and maintaining a relative sinus rhythm refractory to beta-blockers. To optimize heart rate control, it is recommended to pursue an aggressive up-titration of ivabradine. This approach may ameliorate tachycardia-induced hypotension by incrementally enhancing cardiac output and allow further up-titration of agents aimed at ameliorating heart failure, such as beta-blockers. Both the modulation of heart rate itself and the up-titration of agents targeting heart failure lead to cardiac reverse remodeling, consequently culminating in a subsequent reduction in mortality and morbidity. A novel overlap theory that our team proposed recently has emerged in recent times. Under trans-mitral Doppler echocardiography, the E-wave and A-wave closely juxtapose one another without any overlapping at the optimal heart rate. Employing echocardiography-guided ivabradine for heart-rate modulation to minimize the overlap between the E-wave and A-wave appears to confer substantial benefits to patients with heart failure. This approach facilitates superior cardiac reverse remodeling and yields more favorable clinical outcomes when compared to those patients who do not receive echocardiography-guided care. The next pertinent issue revolves around the potential expansion of ivabradine's clinical indications to encompass a broader spectrum of diseases. It is imperative to acknowledge that ivabradine may not yield clinically significant benefits in patients afflicted by heart failure with preserved ejection fraction, acute heart failure, sepsis, or stable angina. An important fact yet to be explored is the clinical applicability of ivabradine in patients with atrial fibrillation, a concern that beckons future investigation. In this review, the concept of overlap theory it introduced, along with its application to expand the indication of ivabradine and the overlap theory-guided optimal ivabradine therapy.

Heart rate/temperature ratio: A practical prognostic indicator for critically ill patients with sepsis

Background

We hypothesize that the heart rate/temperature ratio can predict intensive care unit (ICU) mortality in critical ill patients with sepsis. We aimed to explore the association between the heart rate/temperature ratio and ICU mortality in patients with sepsis.

Methods

We conducted this study utilizing a comprehensive critical care medicine database. The primary endpoint assessed was ICU mortality. A multivariable logistic regression model was employed to determine the independent impact of the heart rate to temperature ratio on ICU mortality.

Results

The study included 12,321 patients. A nonlinear relationship was observed between the heart rate/temperature ratio and ICU mortality, with an inflection point identified at 2.22. The results from the Multivariable logistic regression analysis revealed that the heart rate/temperature ratio independently contributed to the risk of ICU mortality. In model II, there was a 55 % higher ICU mortality rate with a heart rate/temperature ratio greater than 2.22 than with that less than 2.22 (odds ratio [OR] = 1.55, 95 % confidence interval [CI] 1.35-1.77). Moreover, an elevated heart rate/temperature ratio as a continuous variable showed a positive association with ICU mortality (OR = 2.14; 95 % CI: 1.87-2.45). The impact of the heart rate/temperature ratio on ICU mortality remained consistent across all subgroup variables. The sensitivity analysis results consistently supported the primary outcome, with an E value of 2.47. This suggests that the influence of unmeasured confounders on the observed outcomes was minimal, thereby confirming the robustness of the findings.

Conclusions

The heart rate/temperature ratio is a readily available and convenient indicator in a clinical setting. Elevated heart rate/temperature ratios, particularly those exceeding 2.22, are strongly linked to a high ICU mortality rate among critically ill sepsis patients.

Single-cell Sequence Analysis Combined with Multiple Machine Learning to Identify Markers in Sepsis Patients: LILRA5

Sepsis is a disease with a very high mortality rate, mainly involving an immune-dysregulated response due to bacterial infection. Most studies are currently limited to the whole blood transcriptome level; however, at the single cell level, there is still a great deal unknown about specific cell subsets and disease markers. We obtained 29 peripheral blood single-cell sequencing data, including 66,283 cells from 10 confirmed samples of sepsis infection and 19 healthy samples. Cells related to the sepsis phenotype were identified and characterized by the "scissor" method. The regulatory relationships of sepsis-related phenotype cells in the cellular communication network were clarified using the "cell chat" method. The least absolute shrinkage and selection operator (LASSO), support vector machine (SVM), and random forest (RF) were used to identify sepsis signature genes of diagnostic value. External validation was performed using multiple datasets from the GEO database (GSE28750, GSE185263, GSE57065) and 40 clinical samples. Bayesian algorithm was used to calculate the regulatory network of LILRA5 co-expressed genes. The stability of atenolol-targeting LILRA5 was determined by molecular docking techniques. Ultimately, action trajectory and survival analyses demonstrate the effectiveness of atenolol-targeted LILRA5 in treating patients with sepsis. We successfully identified 1215 healthy phenotypic cells and 462 sepsis phenotypic cells. We focused on 447 monocytes of the sepsis phenotype. Among the cellular communications, there were a large number of differences between these cells and other immune cells showing a significant inflammatory phenotype compared to the healthy phenotypic cells. Together, the three machine learning algorithms identified the LILRA5 marker gene in sepsis patients, and validation results from multiple external datasets as well as real-world clinical samples demonstrated the robust diagnostic performance of LILRA5. The AUC values of LILRA5 in the external datasets GSE28750, GSE185263, and GSE57065 could reach 0.875, 0.940, and 0.980, in that order. Bayesian networks identified a large number of unknown regulatory relationships for LILRA5 co-expression. Molecular docking results demonstrated the possibility of atenolol targeting LILRA5 for the treatment of sepsis. Behavioral trajectory analysis and survival analysis demonstrate that atenolol has a desirable therapeutic effect. LILRA5 is a marker gene in sepsis patients, and atenolol can stably target LILRA5.

Evaluating the effects of Esmolol on cardiac function in patients with Septic cardiomyopathy by Speck-tracking echocardiography-a randomized controlled trial

BACKGROUND

Esmolol as one treatment of sepsis induced cardiomyopathy (SIC) is still controversial. The objective of this study is to evaluate cardiac function after reducing heart rate by Esmolol in patients with SIC using speck-tracking echocardiography.

METHODS

This study was a single-center, prospective, and randomized controlled study. A total of 100 SIC patients with a heart rate more than 100/min, admitted to the Intensive Care Department of Tianjin Third Central Hospital from March 1, 2020 to September 30, 2021, were selected as the research subjects. They were randomly divided into the Esmolol group (Group E) and the conventional treatment group (Group C), each with 50 cases. The target heart rate of patients in Group E was controlled between 80/min and 100/min. Speck-tracking echocardiography (STE) and pulse indicating continuous cardiac output monitoring (PICCO) were performed in both groups at 1 h, 24 h, 48 h, 72 h, 96 h and 7 d after admission, with data concerning left ventricular global longitudinal strain (GLS), left ventricular ejection fraction (LVEF) and global ejection fraction (GEF), left ventricular systolic force index (dP/dtmx) were obtained, respectively. Hemodynamics and other safety indicators were monitored throughout the whole process. These subjects were followed up to 90 d, with their mortality recorded at Day 28 and Day 90, respectively. Statistical analyses were performed using SPSS version 21.

RESULTS

With 24 h of Esmolol, all patients in Group E achieved the target heart rate, and there was no deterioration of GLS, or adverse events. However, compared with those in Group C, their GLS, GEF and dP/dtmx were increased, and the difference was statistically significant (P > 0.05). Compared with patients in Group C, those in Group E had lower short-term mortality, and logistic regression analysis also suggested that Esmolol improved patient outcomes.

CONCLUSION

In SIC patients, the application of Esmolol to lower heart rate decreased their short-term mortality while not making any impairment on the myocardial contractility.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR2100047513. Registered June 20, 2021- Retrospectively registered, http://www.chictr.org.cn/index.aspx . The study protocol followed the CONSORT guidelines. The study protocol was performed in the relevant guidelines.

Biomedical Imaging in Experimental Models of Cardiovascular Disease

Major advances in biomedical imaging have occurred over the last 2 decades and now allow many physiological, cellular, and molecular processes to be imaged noninvasively in small animal models of cardiovascular disease. Many of these techniques can be also used in humans, providing pathophysiological context and helping to define the clinical relevance of the model. Ultrasound remains the most widely used approach, and dedicated high-frequency systems can obtain extremely detailed images in mice. Likewise, dedicated small animal tomographic systems have been developed for magnetic resonance, positron emission tomography, fluorescence imaging, and computed tomography in mice. In this article, we review the use of ultrasound and positron emission tomography in small animal models, as well as emerging contrast mechanisms in magnetic resonance such as diffusion tensor imaging, hyperpolarized magnetic resonance, chemical exchange saturation transfer imaging, magnetic resonance elastography and strain, arterial spin labeling, and molecular imaging.

Beta-blockers in septic shock: What is new?

The use of beta(β)-blockers during septic shock aimed at countering peripheral adrenergic stress may be justified by the early reduction in deleterious effects resulting from sympathetic overactivation, and could improve the prognosis of patients in septic shock. Animal studies have demonstrated either a maintenance or increase in cardiac output (CO) despite the decrease in heart rate (HR) associated with improved myocardial performance. The mechanism by which β-blockers alter hemodynamics in septic shock is debated; however, preclinical and clinical data show that β-blockers are safe when started at a low dose. Recent publications (2019-2021) on adrenergic β1 receptor antagonists used in septic shock indicate that esmolol and landiolol should not be used in the early phase. While there is no optimal timing for their administration, a minimum of 12 h after the initiation of vasopressor therapy in stabilized euvolemic patients is a reasonable option. Patients should have a normal cardiac function, although a slight depression is compatible with landiolol use under hemodynamic monitoring. Slow titration in patients who remain tachycardic is preferable to rapid titration. When used to decrease HR, landiolol is also effective in reducing the incidence of new arrhythmias. Results of a well-performed and well-powered randomized controlled trial (RCT) demonstrating a positive effect on survival - or at least on hard surrogates such as the incidence/duration of organ failure - are pending.

Non-invasive Early Prediction of Septic Acute Kidney Injury by Doppler-Based Renal Resistive Indexes Combined With Echocardiographic Parameters: An Experimental Study

Non-invasive early prediction of septic acute kidney injury (S-AKI) is still urgent and challenging. Increased Doppler-based renal resistive index (RRI) has been shown to be associated with S-AKI, but its clinical use is limited, which may be explained by the complex effects of systemic circulation. Echocardiogram allows non-invasive assessment of systemic circulation, which may provide an effective supplement to RRI. To find the value of RRI combined with echocardiographic parameters in the non-invasive early prediction of S-AKI, we designed this experiment with repeated measurements of ultrasonographic parameters in the early stage of sepsis (3, 6, 12, and 24 h) in cecum ligation and puncture (CLP) rats (divided into AKI and non-AKI groups at 24 h based on serum creatinine), with sham-operated group serving as controls. Our results found that RRI alone could not effectively predict S-AKI, but when combined with echocardiographic parameters (heart rate, left ventricular end-diastolic internal diameter, and left ventricular end-systolic internal diameter), the predictive value was significantly improved, especially in the early stage of sepsis (3 h, AUC: 0.948, 95% CI 0.839–0.992, P < 0.001), and far earlier than the conventional renal function indicators (serum creatinine and blood urea nitrogen), which only significantly elevated at 24 h. Our method showed novel advances and potential in the early detection of S-AKI.

Impact of Ivabradine on renal function in septic patient with early renal impairment

Background

Acute kidney injury (AKI) with sepsis increases mortality significantly. The pathophysiology of AKI during sepsis is complex and multifactorial. Lower heart rate is associated with better survival in patients with multiple organ dysfunction syndrome (MODS), a disease mostly caused by sepsis. In our study, we hypnotized that use of ivardrabine as heart rate reducing agent in septic patient with renal impairment may improve renal function.

Results

Fifty patients with sepsis with early renal impairment were divided in 1: 1 ratio to receive Ivabradine (group I) or not (group C). The average age of the included patients was almost 45 years, chest disorders were the main cause of sepsis in both groups. There were statistically significant differences between both groups in terms of reduction of heart rate group (I) (68.13 ± 3.34) versus (group C) (87.04 ± 3.23) and (P < 0.001) also, improvement in eGFR by Cystatin c in group (I) (103.32 ± 6.96) versus (group C) (96.25 ± 6.36) and (P < 0.001) also vasopressor dosage consumption (P < 0.001). As regards secondary outcomes, there were no statistically significant differences between study’s groups in terms of length of hospital stay (P = 0.390), need for hemodialysis (P = 0.384), and mortality (P = 1.000).

Conclusions

We concluded that Ivabradine as an adjuvant therapy in septic patients with renal impairment is promising agent to reduce such impairment.

Trial registration

Pan African Clinical Trial Registry: Identification number for the registry is PACTR201911806644230.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42077-021-00162-6.

β-Blockers, Tachycardia, and Survival Following Sepsis: An Observational Cohort Study

BACKGROUND

Sepsis is associated with excessive release of catecholamines, which causes tachycardia and is correlated with poor clinical outcome. β-Blockers (BBs) may blunt this effect on heart rate (HR). The objective of this study is to assess whether long-term BB therapy is associated with better clinical outcomes in patients with sepsis admitted to internal medicine wards.

METHODS

We performed a single-center, observational cohort study. We included adult patients who were hospitalized in medicine departments due to sepsis. A propensity score model for BB therapy was used to match patients. The primary outcome was the 30-day all-cause mortality rate. A multivariate analysis was performed to identify risk factors for an adverse outcome. Patients were stratified according to absolute tachycardia (HR ≥100/min) or relative tachycardia at presentation (tachycardia index above the third quartile, with tachycardia index defined as the ratio of HR to temperature).

RESULTS

A total of 1186 patients fulfilled the inclusion criteria. In the propensity-matched cohort patients given BB treatment were younger (median age [interquartile range], 74 [62-82] vs 81 [68-87] years; P ≤ .001). BB treatment was associated with reduction in 30-day mortality rates for patients with absolute tachycardia (odds ratio, 0.406; 95% confidence interval, .177-.932). Final model with interaction variable of BB treatment with HR was associated with short-term survival (odds ratio, 0.38; 95% confidence interval, .148-.976). Selective BB therapy had a stronger protective effect than nonselective BB therapy.

CONCLUSIONS

Long-term BB therapy was associated with decreased mortality rate in patients hospitalized with sepsis in internal medicine wards exhibiting absolute and relative tachycardia.