If Channel Inhibition With Ivabradine Does Not Improve Cardiac and Vascular Function in Experimental Septic Shock

Ivabradine in Septic Shock: A Narrative Review

In patients with septic shock, compensatory tachycardia initially serves to maintain adequate cardiac output and tissue oxygenation but may persist despite appropriate fluid and vasopressor resuscitation. This sustained elevation in heart rate and altered heart rate variability, indicative of autonomic dysfunction, is a well-established independent predictor of adverse outcomes in critical illness. Elevated heart rate exacerbates myocardial oxygen demand, reduces ventricular filling time, compromises coronary perfusion during diastole, and impairs the isovolumetric relaxation phase of the cardiac cycle, contributing to ventricular-arterial decoupling. This also leads to increased ventricular and atrial filling pressures, with a heightened risk of arrhythmias. Ivabradine, a highly selective inhibitor of the sinoatrial node's pacemaker current (If or "funny" current), mitigates heart rate by modulating diastolic depolarization slope without affecting contractility. By exerting a selective chronotropic effect devoid of negative inotropic properties, ivabradine shows potential for improving hemodynamics in septic shock patients with cardiac dysfunction. This review evaluates the plausible mechanisms and existing evidence regarding the utility of ivabradine in managing patients with septic shock.

LOW DOSE OF ESMOLOL ATTENUATES SEPSIS-INDUCED IMMUNOSUPPRESSION VIA MODULATING T-LYMPHOCYTE APOPTOSIS AND DIFFERENTIATION

ABSTRACT

Background: Immunosuppression caused by immune cell apoptosis and an imbalance of T helper 2 cells (T H 2) and T helper 1 cells (T H 1), is associated with poor outcomes in septic patients. Esmolol was reported to improve survival by modulating immune responses in septic shock. Whether esmolol could alleviate sepsis-induced immunosuppression and the optimal dose are unclear. Methods: Four hours after cecal ligation and puncture (CLP), Wistar rats were randomized into CLP, CLP + E-5 (esmolol: 5 mg·kg -1 ·h -1 ) and CLP + E-18 (esmolol: 18 mg·kg -1 ·h -1 ) groups. Eight rats were underwent sham operation. Eighteen hours after CLP, hemodynamics and organ histological injuries were evaluated, peripheral blood mononuclear cells apoptosis and T-lymphocyte subsets counts were determined by flow cytometry, and the expression of p-Akt, Bcl-2, cleaved Caspase-3, and p-Erk1/2 in splenic CD4 + T-lymphocytes was determined by western blot and immunohistochemistry. β 1 -Adrenoreceptor expressions were evaluated using real-time polymerase chain reaction and immunohistochemistry. Results: Cecal ligation and puncture induced tachycardia, hypotension, hyperlactatemia, and multiple organ injury. Heart rate was unchanged in the CLP + E-5 group but decreased in the CLP + E-18 group. Hypotension, lactatemia, and multiple organ injuries were improved only in the CLP + E-5 group. T-lymphocyte apoptosis and T H 2/T H 1 ratio was decreased in CLP + E-5 but not in CLP + E-18. p-Akt and Bcl-2 expressions were increased, while cleaved Caspase-3 and p-Erk1/2 expressions were decreased in CLP + E-5. β 1 -Adrenoreceptor expressions were unchanged in both CLP + E-5 and CLP + E-18 groups. Conclusions: Low dose of esmolol reduced T-lymphocyte apoptosis and restored T H 2/T H 1 ratio in septic shock. Esmolol might modulate Akt/Bcl-2/Caspase-3 pathway to relieve T-lymphocyte apoptosis and inhibit Erk1/2 activity to decrease T H 0 differentiation to T H 2. Esmolol may be a potential immunoregulator of septic shock.

Sinus Tachycardia: a Multidisciplinary Expert Focused Review

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

Assessment of hypertension and other factors associated with the severity of disease in COVID-19 pneumonia, Addis Ababa, Ethiopia: A case-control study

BACKGROUND

Various reports suggested that pre-existing medical illnesses, including hypertension and other demographic, clinical, and laboratory factors, could pose an increased risk of disease severity and mortality among COVID-19 patients. This study aimed to assess the relation of hypertension and other factors to the severity of COVID-19 pneumonia in patients discharged from Eka Kotebe Hospital in June-September, 2020.

METHODS

This is a single-center case-control study of 265 adult patients discharged alive or dead, 75 with a course of severe COVID-19 for the cases arm and 190 with the non-severe disease for the control arm. Three age and sex-matched controls were selected randomly for each patient on the case arm. Chi-square, multivariable binary logistic regression, and odds ratio (OR) with a 95% confidence interval was used to assess the association between the various factors and the severity of the disease. A p-value of <0.05 is considered statistically significant.

RESULTS

Of the 265 study participants, 80% were male. The median age was 43 IQR(36-60) years. Both arms had similar demographic characteristics. Hypertension was strongly associated with the severity of COVID-19 pneumonia based on effect outcome adjustment (AOR = 2.93, 95% CI 1.489, 5.783, p-value = 0.002), similarly, having diabetes mellitus (AOR = 3.17, 95% CI 1.374, 7.313, p-value<0.007), chronic cardiac disease (AOR = 4.803, 95% CI 1.238-18.636, p<0.023), and an increase in a pulse rate (AOR = 1.041, 95% CI 1.017, 1.066, p-value = 0.001) were found to have a significant association with the severity of COVID-19 pneumonia.

CONCLUSIONS

Hypertension was associated with the severity of COVID-19 pneumonia, and so were diabetes mellitus, chronic cardiac disease, and an increase in pulse rate.

Heart Rate in Patients with SARS-CoV-2 Infection: Prevalence of High Values at Discharge and Relationship with Disease Severity

The most common arrhythmia associated with COronaVIrus-related Disease (COVID) infection is sinus tachycardia. It is not known if high Heart Rate (HR) in COVID is simply a marker of higher systemic response to sepsis or if its persistence could be related to a long-term autonomic dysfunction. The aim of our work is to assess the prevalence of elevated HR at discharge in patients hospitalized for COVID-19 and to evaluate the variables associated with it. We enrolled 697 cases of SARS-CoV2 infection admitted in our hospital after February 21 and discharged within 23 July 2020. We collected data on clinical history, vital signs, laboratory tests and pharmacological treatment. Severe disease was defined as the need for Intensive Care Unit (ICU) admission and/or mechanical ventilation. Median age was 59 years (first-third quartile 49, 74), and male was the prevalent gender (60.1%). 84.6% of the subjects showed a SARS-CoV-2 related pneumonia, and 13.2% resulted in a severe disease. Mean HR at admission was 90 ± 18 bpm with a mean decrease of 10 bpm to discharge. Only 5.5% of subjects presented HR > 100 bpm at discharge. Significant predictors of discharge HR at multiple linear model were admission HR (mean increase = β = 0.17 per bpm, 95% CI 0.11; 0.22, p < 0.001), haemoglobin (β = −0.64 per g/dL, 95% CI −1.19; −0.09, p = 0.023) and severe disease (β = 8.42, 95% CI 5.39; 11.45, p < 0.001). High HR at discharge in COVID-19 patients is not such a frequent consequence, but when it occurs it seems strongly related to a severe course of the disease.

The autonomic nervous system in septic shock and its role as a future therapeutic target: a narrative review

The autonomic nervous system (ANS) regulates the cardiovascular system. A growing body of experimental and clinical evidence confirms significant dysfunction of this regulation during sepsis and septic shock. Clinical guidelines do not currently include any evaluation of ANS function during the resuscitation phase of septic shock despite the fact that the severity and persistence of ANS dysfunction are correlated with worse clinical outcomes. In the critical care setting, the clinical use of ANS-related hemodynamic indices is currently limited to preliminary investigations trying to predict and anticipate imminent clinical deterioration. In this review, we discuss the evidence supporting the concept that, in septic shock, restoration of ANS-mediated control of the cardiovascular system or alleviation of the clinical consequences induced by its dysfunction (e.g., excessive tachycardia, etc.), may be an important therapeutic goal, in combination with traditional resuscitation targets. Recent studies, which have used standard and advanced monitoring methods and mathematical models to investigate the ANS-mediated mechanisms of physiological regulation, have shown the feasibility and importance of monitoring ANS hemodynamic indices at the bedside, based on the acquisition of simple signals, such as heart rate and arterial blood pressure fluctuations. During the early phase of septic shock, experimental and/or clinical studies have shown the efficacy of negative-chronotropic agents (i.e., beta-blockers or ivabradine) in controlling persistent tachycardia despite adequate resuscitation. Central α-2 agonists have been shown to prevent peripheral adrenergic receptor desensitization by reducing catecholamine exposure. Whether these new therapeutic approaches can safely improve clinical outcomes remains to be confirmed in larger clinical trials. New technological solutions are now available to non-invasively modulate ANS outflow, such as transcutaneous vagal stimulation, with initial pre-clinical studies showing promising results and paving the way for ANS modulation to be considered as a new potential therapeutic target in patients with septic shock.

Tachycardia control in septic shock with esmolol and ivabradine: a comparison on heart function

Persisting tachycardia is often observed in resuscitated septic shock patients, and it is an independent risk factor for increased mortality. Recently, several drugs, such as esmolol and ivabradine, have been proved to be beneficial in HR control, but their overall impact on cardiac functions needs further investigation. The aim of this study is to study the effects of the two drugs on heart function in a protocol of polymicrobial septic shock and resuscitation. Twelve pigs were divided into three experimental groups: the esmolol-treated group (n=4), the ivabradine-treated group (n=5) and the control group (n=3). Cardiac autonomic activity was estimated by heart rate variability (HRV) indices and baroreflex sensitivity (BRS). The Buckberg index was adopted to evaluate myocardial oxygenation efficiency. Septic shock induced a severe autonomic dysfunction and a lower cardiac efficiency, not resolved by fluids resuscitation. The administration of the drugs improved both the HRV and the BRS, but this favourable condition was preserved after noradrenaline administration only in the esmolol group. The interaction of esmolol with the autonomic system is beneficial in septic shock to restore an improved condition of HRV and control, while ivabradine is not as effective when administered in adjunction to noradrenaline.

Reducing tachycardia in septic shock patients: do esmolol and ivabradine have a chronotropic effect only?

An elevated heart rate (HR) often persists in resuscitated septic shock patients, increasing the risk of mortality. Several drugs for HR control, such as esmolol and ivabradine, have been tested in the recent years, but their benefit on the overall cardiovascular system is still under investigation. The aim of this study is to investigate the hemodynamic effects of the two drugs in a protocol of polymicrobial septic shock and resuscitation, mainly focusing on the vascular function. Twelve pigs were divided into three experimental groups: the esmolol-treated group (n=4), the ivabradine-treated group (n=5) and the control group (n=3). The characteristic arterial time constant τ was computed on aortic arterial pressure (AoP), together with estimates of total arterial compliance and peripheral resistance. Power spectral analysis of aortic and radial diastolic BP oscillations was performed to estimate the sympathetic autonomic control of vascular tone. Septic shock induced a severe cardiac and vascular disarray, only partially resolved by resuscitation. The administration of esmolol, but not ivabradine, was beneficial both for cardiac and vascular function, thereby its adjunction to standard therapies could help to improve patient's condition and optimize the resuscitation strategies.Clinical Relevance-This study shows a potential beneficial effect of esmolol on the arterial tree.

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

BACKGROUND

Tachycardia is a hallmark of sepsis. An elevated heart rate could impair ventricular filling and increase myocardial oxygen demand. β-Blockers and ivabradine (a selective inhibitor of If channels in the sinoatrial node) are both able to control sinus tachycardia, with the latter drug being devoid of negative inotropic effect. This work aimed at assessing the hemodynamic effects of ivabradine as compared with a β-blocker (atenolol) during murine peritonitis.

METHODS

Ivabradine (3 μg/g), atenolol (3 μg/g), or placebo was administered intraperitoneally 2 h after induction of peritonitis (cecal ligation and puncture) in male C57BL6 mice. The authors used invasive (left ventricular catheterization) and noninvasive (transthoracic echocardiography) monitoring to assess hemodynamics 20 h after surgery, including heart rate, blood pressure, left ventricular systolic, and diastolic function (n = 10 mice/group). The authors also assessed overall mortality 30 and 60 h after surgery in a distinct subset of animals (n = 20 mice/group). Descriptive data are presented as median (25th to 75th percentile).

RESULTS

As compared with placebo (601 beats/min [547 to 612]), ivabradine (447 beats/min [430 to 496]) and atenolol (482 beats/min [412 to 505]) blunted sepsis-induced tachycardia assessed by transthoracic echocardiography in awake animals (P < 0.001 and P = 0.004, respectively). Unlike ivabradine, atenolol reduced cardiac output, systolic blood pressure, and left ventricular systolic function (as assessed by ejection fraction, maximal left ventricular pressure rise, and anterior wall strain rate) as compared with septic mice receiving placebo. There was no difference in survival 60 h after sepsis induction with ivabradine (6 of 20, 30%) or atenolol (7 of 20, 35%), as compared with placebo (5 of 20, 25%; P = 0.224).

CONCLUSIONS

Heart rate control could be similarly achieved by ivabradine or atenolol, with preservation of blood pressure, cardiac output, and left ventricular systolic function with the former drug.

β-bloquants dans la prise en charge du choc septique

Les adrénorécepteurs α et en particulier β sont les principales cibles de l’adrénaline et de la noradrénaline libérées par le système sympathique activé. Durant le choc septique, la dysautonomie est une stimulation prolongée à un haut niveau d’intensité du système nerveux sympathique à l’origine d’une altération de la contractilité, de la vasoréactivité et d’une immunodépression. Ainsi, l’administration précoce d’un traitement β-bloquant lors du choc septique pourrait pondérer les effets délétères de cette surstimulation sympathique. Néanmoins, si les preuves expérimentales sont en faveur de cette approche, l’accumulation des preuves cliniques reste encore insuffisante.

Effect of ivabradine, a funny current inhibitor, on portal hypertensive rats

BACKGROUND

Ivabradine is a funny current inhibitor which is administered to patients with congestive heart failure to reduce their heart rate (HR) and attenuate oxidative stress. Chronic liver diseases are characterized by portal hypertension and hyperdynamic circulation with tachycardia. The present study aimed to investigate the effect of ivabradine on portal hypertension.

METHODS

Male Sprague-Dawley rats received partial portal vein ligation (PVL) to induce portal hypertension. The PVL rats were randomly allocated to receive either vehicle or ivabradine treatment for 10 days. Then the hemodynamic data were collected. The levels of oxidative stress markers and the mRNA expression of nitric oxide synthase (NOS) were measured in the collateral vessel, the superior mesentery artery and the liver. In addition, the collateral vascular responsiveness to arginine vasopressin (AVP) was examined in the ivabradine-treated and vehicle-treated PVL rats.

RESULTS

Treatment with ivabradine significantly lowered the HR (174 ± 20 vs. 374 ± 9 beats/min; p < 0.001) and the superior mesentery arterial flow (SMAf) (6.6 ± 0.3 vs. 9.1 ± 0.7 mL/min/100 g BW; p = 0.005) of the PVL rats compared with the control group. The mean arterial pressure, cardiac index, systemic vascular resistance, portal pressure and serum levels of oxidative stress markers were not significantly affected by ivabradine treatment. In addition, the NOS expression and collateral vascular responsiveness to AVP were not significantly influenced by ivabradine treatment, either.

CONCLUSION

Ivabradine reduced the HR and SMAf in PVL rats, which alleviated the hyperdynamic circulatory state and splanchnic hyperemia of portal hypertension. However, whether these effects would help alleviate portal hypertension-related complications requires further clinical investigations.

Ivabradine: Evidence and current role in cardiovascular diseases and other emerging indications

Increased heart rate (HR) is associated with deleterious effects on several disease conditions. Chronic heart failure (CHF) is one of the cardiovascular diseases with recurrent hospitalization burden and an ongoing drain on health-care expenditure. Despite advancement in medicine, management of CHF remains a challenge to health-care providers. Ivabradine selectively and specifically inhibits the pacemaker I(f) ionic current which reduces the cardiac pacemaker activity. The main effect of ivabradine therapy is the substantial lowering of HR. It does not influence intracardiac conduction, contractility, or ventricular repolarization. As shown in numerous clinical studies, ivabradine improves clinical outcomes and quality of life and reduces the risk of death from heart failure (HF) or other cardiovascular causes. Recently updated HF guidelines recommend ivabradine as a class II indication for reduction of HF hospitalizations. Based on the principle of benefits of reduced HR, the ivabradine in patients with ischemic heart disease, sepsis, and multiple organ dysfunction syndrome has also been studied. It can also be a useful agent for HR reduction in patients with contraindications to use beta-blockers or those who cannot tolerate them. In this review, we provide an overview of efficacy and safety of ivabradine and its combination with currently recommended pharmacological therapy in different conditions.

Ivabradine Attenuates the Microcirculatory Derangements Evoked by Experimental Sepsis

Background

Experimental data suggest that ivabradine, an inhibitor of the pacemaker current in sinoatrial node, exerts beneficial effects on endothelial cell function, but it is unclear if this drug could prevent microcirculatory dysfunction in septic subjects, improving tissue perfusion and reducing organ failure. Therefore, this study was designed to characterize the microcirculatory effects of ivabradine on a murine model of abdominal sepsis using intravital videomicroscopy.

Methods

Twenty-eight golden Syrian hamsters were allocated in four groups: sham-operated animals, nontreated septic animals, septic animals treated with saline, and septic animals treated with ivabradine (2.0 mg/kg intravenous bolus + 0.5 mg · kg−1 · h−1). The primary endpoint was the effect of ivabradine on the microcirculation of skinfold chamber preparations, assessed by changes in microvascular reactivity and rheologic variables, and the secondary endpoint was its effects on organ function, evaluated by differences in arterial blood pressure, motor activity score, arterial blood gases, and hematologic and biochemical parameters among groups.

Results

Compared with septic animals treated with saline, those treated with ivabradine had greater functional capillary density (90 ± 4% of baseline values vs. 71 ± 16%; P &lt; 0.001), erythrocyte velocity in capillaries (87 ± 11% of baseline values vs. 62 ± 14%; P &lt; 0.001), and arteriolar diameter (99 ± 4% of baseline values vs. 91 ± 7%; P = 0.041) at the end of the experiment. Besides that, ivabradine-treated animals had less renal, hepatic, and neurologic dysfunction.

Conclusions

Ivabradine was effective in reducing microvascular derangements evoked by experimental sepsis, which was accompanied by less organ dysfunction. These results suggest that ivabradine yields beneficial effects on the microcirculation of septic animals.

Effects of low doses of esmolol on cardiac and vascular function in experimental septic shock

Background

Administration of a selective β1-blocker, such as esmolol, in human septic shock has demonstrated cardiovascular protective effects related to heart rate reduction. Certain experimental data also indicate that esmolol exerts systemic anti-inflammatory and beneficial effects on vascular tone. Thus, the present study aimed to determine whether a non-chronotropic dose of esmolol maintains its protective cardiovascular and anti-inflammatory effects in experimental septic shock.

Methods

Four hours after cecal ligation and puncture (CLP), Wistar male rats were randomly allocated to the following groups (n = 8): CLP, CLP + E-1 (esmolol: 1 mg.kg⁻¹.h⁻¹), CLP + E-5 (esmolol: 5 mg.kg⁻¹.h⁻¹), CLP + E-18 (esmolol: 18 mg.kg⁻¹.h⁻¹). An additional eight rats underwent sham operation. All rats received a continuous infusion of saline, analgesic and antibiotics 4 hours after the surgery. Assessment at 18 hours included in vivo cardiac function assessed by echocardiography and ex vivo vasoreactivity assessed by myography. Circulating cytokine levels (IL-6 and IL-10) were measured by ELISA. Cardiac and vascular protein expressions of p-NF-κB, IκBα, iNOS, p-AKT/AKT and p-eNOS/eNOS were assessed by western blotting.

Results

CLP induced tachycardia, hypotension, cardiac output reduction, hyperlactatemia and vascular hypo-responsiveness to vasopressors. Compared to CLP animals, heart rate was unchanged in CLP + E-1 and CLP + E-5 but was reduced in CLP + E-18. Stroke volume, cardiac output, mean arterial pressure and lactatemia were improved in CLP + E-1 and CLP + E-5, while vascular responsiveness to phenylephrine was only improved in CLP + E-5 and CLP + E-18. Plasma IL-6 levels were decreased in all esmolol groups. p-NF-κB was decreased in both cardiac and vascular tissues in CLP + E-5 and CLP + E-18.

Conclusion

In experimental septic shock, low doses of esmolol still improved cardiac function and vasoreactivity. These benefits appear to be associated with a modulation of inflammatory pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1580-2) contains supplementary material, which is available to authorized users.