Clinical, genetic and functional analysis of R562S-Kv7.1 mutation associated with long QT syndrome type 1

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Ministry of Education, Youth and Sports of the Czech Republic

Introduction

Loss-of-function variants of the KCNQ1 gene are associated with life-threatening arrhythmogenic long QT syndrome type 1 (LQT1). This gene encodes structure of the slow delayed rectifier potassium channel (IKs). Some functional characteristics of the C-terminal KCNQ1 variant c.1686G > C (p.R562S) have been recently described [1]. However, accumulation of the current under beta-adrenergic stimulation, essential for shortening the action potential duration during exercise, have not been tested.

Purpose

The aim of this study was to analyse clinical and genetic characteristics of the R562S variant in our patients and to investigate impact of the variant on IKs channel function with a special focus on reactivity of the channels on beta-adrenergic stimulation.

Methods

The clinical diagnosis was established according to ESC Guidelines including QTc analysis at rest and after exercise. The molecular genetics diagnostics followed according to current practices (the massive parallel sequencing since 2016). The biophysical analysis was performed on Chinese hamster ovary cells (CHO) by the whole cell patch clamp technique at 37 °C. CHO cells were transiently transfected with wild type (WT) and/or R562S human IKs channels (KCNQ1/KCNE1/Yotiao, 1:2:4). Cyclic adenosine monophosphate (cAMP, 200 µM) and okadaic acid (OA, 0.2 µM) in the pipette solution were used to simulate the beta-adrenergic stimulation. In the confocal microscopy experiments, expression of Yotiao was omitted and GFP-tagged KCNQ1 was used.

Results

The variant R562S-Kv7.1 has been identified in 7 heterozygous carriers from 3 putatively unrelated families in the Czech Republic. The genotype was associated with long QT syndrome phenotype (prolonged QTc, symptoms including syncopes and aborted cardiac arrest) in some of the carriers. The basic functional analysis proved that both homozygous and heterozygous R562S channels are expressed on the cell membrane (confocal microscopy) and carry IKs (whole cell patch clamp) which agrees with the recently published data on this variant. Importantly, reactivity on beta-adrenergic stimulation was absent in both homozygous and heterozygous R562S channels (n = 14 and 8, respectively), but present in the wild-type channels (increase by 51.4 ± 11.1 % at 120-s cAMP/OA diffusion; n = 12).

Conclusions

The R562S-Kv7.1 variant may be a founder LQT1 variant in our region which will be further investigated in the future. This variant impairs response of IKs channel to beta-adrenergic stimulation. Absence of this essential regulation may considerably aggravate the channel dysfunction and, thus, may result in life-threatening arrhythmias in R562S carriers during exercise.

Aminophylline affects the cardiac rat inward rectifier potassium current in a dual way

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Ministry of Education, Youth and Sports of the Czech Republic

Introduction

Aminophylline, a bronchodilator used in clinical practice to treat namely severe astma attacks, often induces atrial fibrillation in patients. Modifications of the inward rectifier potassium current IK1 are known to play a role in the genesis of fibrillation.

Purpose

We aimed to investigate the effect of aminophylline at clinically-relevant concentrations between 3 and 100 µM on IK1 in isolated rat ventricular myocytes.

Methods

Experiments were performed by the whole cell patch clamp technique on enzymatically isolated rat right ventricular myocytes at room temperature. IK1 was measured as the current sensitive to 100 µM Ba2+.

Results

We observed a dual steady-state effect of aminophylline at most of the applied concentrations. Either inhibition or activation was apparent in individual cells during application of aminophylline at a given concentration. The smaller was magnitude of the control IK1, the more likely was activation of the current in the presence of aminophylline and vice versa (tested at 10 and 30 µM). The effect was voltage-independent and fully reversible during the subsequent wash-out. The mean aminophylline effect was inhibitory at all concentrations (10, 15, 4, and 23%-inhibition at -50 mV at 3, 10, 30, and 100 µM, respectively). Using a modified version of the population model of IK1 channels that we published before, the dual effect can be explained by interaction of aminophylline with two channel populations in a different way, the first one being inhibited and the second one being activated by the drug. Considering various fractions of these two channel populations in individual cells, varying effects observed in the measured cells can be simulated.

Conclusions

Aminophylline at clinically-relevant concentrations affects IK1 in rat ventricular myocytes in a dual way, showing both the steady-state activation and inhibition in various cells, even at the same concentration. It may be related to a different effect of the drug on various Kir2.x subunits forming the heterotetrameric IK1 channels present at the cell membrane of a single cell.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Individual goal-directed intraoperative fluid management of initially hypovolemic patients for elective major urological surgery

BACKGROUND

The impact of different approaches to fluid management during intraoperative volume resuscitation in patients undergoing major elective surgery is poorly defined. We compared volume effectiveness of crystalloid and colloid substitution aimed to maintain the cardiac index (CI) between 2.6 and 3.8 l/min/m(2) as measured by transesophageal Doppler (TED).

METHODS

A total of 115 urological patients were enrolled in the prospective randomized trial and then randomized into 2 groups, one with volume therapy based on crystalloids (n = 57) and the other with colloids (n = 58). A TED probe was inserted and then hemodynamic optimization (therapy with Ringer's solution or hydroxyethyl starch 6 % 130/0.4 and administration of vasoactive drugs) was started according to TED variables to maintain the CI between 2.6 and 3.8 l/min/m(2).

RESULTS

We observed high incidence of CI < 2.6 l/min/m(2) after induction of anesthesia (75 %) in both groups. There were no significant differences in demographic characteristics, ASA classification, length of surgery, estimated blood loss and the CI during surgery. To maintain the CI within the requested interval, significantly different amounts of crystalloids were needed as compared to colloid (median: 5000 ml vs 1500 ml). In the CRY group, more patients were treated by vasodilatators (40.4 vs 20.7 %).

CONCLUSIONS

The study confirmed that crystalloids and colloids are effective in correcting flow-related perfusion abnormalities. The significant difference between volumes of crystalloids and colloids proved their different characteristics such as unequal distribution between compartments. The expansion of therapeutic algorithm by using vasoactive drugs allows us to avoid adverse events resulting from fluid overload (Tab. 1, Fig. 5, Ref. 35).

[Serious sepsis treatment in intensive care departments in the Czech Republic - EPOSS Project pilot results]

INTRODUCTION

Severe sepsis is still associated with significant morbidity and mortality, which is however different, as well as its management, depending on the region. What is the situation in the Czech Republic and what is the character of patients with severe sepsis is currently not known. The aim of the project is to describe the processes of care, outcome and characteristics of patients with severe sepsis admitted to the intensive care department of the Czech Republic.

METHODS

This is a multicentre and observational project with retrospective enrollment of patients who meet the criteria for severe sepsis before or within 24 hours after admission to selected intensive care units (ICU EPOSS).

RESULTS

394 patients were analyzed. Median age at admission was 66 (56- 76) years, males predominated (58.9%) and the median APACHE II score on admission was 25 (19- 32). Patients were predominantly medical (56.9%) and most were secondary admitted from other ICU (53.6%). Meeting the criteria of severe sepsis was most frequently within the period (± 4 hours) of admission the EPOSS ICU (77.6%). Median total fluid intake during the first 24 hours was 6,680 (4,840- 9,450) ml. Most patients required mechanical ventilation (58.4%). Compliance with the resuscitation bundle of severe sepsis in our group was very good and was associated with lower mortality of patients. Most frequently, the EPOSS ICU length of stay (LOS) was 7 (3- 15) days and median hospital LOS was 13 (8- 28) days. Hospital mortality in our cohort was 35.8%.

CONCLUSION

Introducing the project, which in its first stage obtained valuable and internationally comparable data about patients with severe sepsis admitted to the involved ICU in the Czech Republic.

[Ventilator-associated pneumonia]

Ventilator-associated pneumonia (VAP) is defined as pneumonia occurring in a patient after intubation with an endotracheal tube or tracheostomy tube lasting for 48 hours or more. It is also one of the most common and fatal infections of patients in ICUs. The diagnostic process in VAP is still underestimated and precise criteria for diagnosis are inconsistent. Delayed diagnosis and subsequent delay in starting appropriate therapy are associated with worse outcomes in patients with VAP. Appropriate dose, adequate route of administration and reasonable length of antibiotic therapy together with de-escalation are the fundamental principles of therapy. Supportive care is also an integral part of the treatment. Implementing preventive procedures according to the local ICU standards is needed for reducing the incidence of VAP effectively.

Exogenous surfactant as a component of complex non-ECMO therapy of ARDS caused by influenza A virus (2009 H1N1)

During the pandemy caused by novel influenza A virus (subgroup H1N1), a significant number of patients became critically ill from respiratory failure. In the most severe cases of primary pneumonia, patients develop refractory hypoxemic acute respiratory distress syndrome (ARDS) with typical computed tomographic findings of multi-lobar alveolar opacities and extremely reduced pulmonary airspace. To reduce the risk of injurious ventilation and promote survival, some authors recommend the use of extracorporeal membrane oxygenation (ECMO). Unfortunately, ECMO is expensive, associated with serious complications, and available at very few centers. Other therapeutic options are clearly needed. Here we report three patients with severe influenza pneumonia who recovered following treatment with porcine surfactant (Tab. 1, Fig. 3, Ref. 6). Full Text in free PDF www.bmj.sk.

Thrombolysis and cardiac arrest

Cardiac arrest (CA) is a serious clinical condition that might be responsible in many cases for death, in other at least for development of irreversible multiple organ dysfunctions. During and after the CA a significant coagulopathy develops causing a decrease in proper tissue perfusion even if an early return of spontaneous circulation (ROSC) is achieved (no-reflow phenomenon). Administration of thrombolytics can solve the problem by destructing the blood clot in both macrocirculation and microcirculation. Results of some clinical trials proving an effectiveness of thrombolysis were published in the literature. Generally, it was done by describing its positive influence on some important clinical outcome measures (24hour survival, number of hospital admissions, better neurological status etc.) without significant increase in the number of bleeding complications. However, recent pivotal evidence based medicine (EBM) trial represented by TROICA study did not confirm the expected positive results. Because of that and also for other reasons (cost, fear of adverse effects, little practice etc.) thrombolysis, although theoretically promising therapeutical intervention, is not overly recommended and used in routine clinical practice in both out-of-hospital and in-hospital settings (Fig. 2, Tab. 4, Ref. 24). Full Text in free PDF www.bmj.sk.

A response to infection in patients with severe sepsis--do we need a "stage-directed therapy concept"?

Excessive forms of the response of organism to infection play an important role in the pathogenesis of severe sepsis. They may consist of either local pro-inflammatory response with a massive release of cytokines into the systemic circulation, or may be presented as an excessive systemic anti-inflammatory response. In the first case, the result is a systemic pro-inflammatory state, characterised by natural stages of the inflammatory response, in which dysfunction of macrocirculation is followed by microcirculation derangement and mitochondrial alteration at the end. These mechanisms are responsible for the development of remote organs failure. The result in the second case is a deactivation of local immunocompetent cells, which results in the risk of uncontrollable growth of microorganisms, especially in organs with an impaired antimicrobial barrier. This may explain the clinically observed recurrence of septic episodes, when a resolution of infection at one site is later replaced with an outbreak of sepsis from another site. A number of therapeutic interventions aimed on the management of causes and consequences of systemic pro-inflammatory state was clinically tested (e.g. antibiotics, goal directed hemodynamic support and inhibitors of coagulation) with surprisingly different effectiveness. The cause of this difference may lie, apart from the frequently discussed inhomogeneity of the studied patient population, also in an incorrect timing of the therapeutic interventions, which does not respect natural stages of the inflammatory response (Fig. 1, Ref. 40).

[Influencing hemostasis in substitute solution treatment]

Hemostasis is an important intricately regulated homeostatic process. During the hospitalization a critically ill patient is often subjected to various external and internal stimuli which have abilities to influence the hemostasis. Administration of substitute solutions could be related to such an adverse effect. This paper tries to describe main mechanisms leading to impair the hemostatic balance during the fluid therapy and outline possibilities of their monitoring. The work also deals with every basic arteficial substitute solutions individually in term of their influence on coagulation. The goal was as well to point out certain controversial conclusions and problems emerging from the effort of synthesis of all information acquired from clinical publications related to the main topic. Generally it is possible to conclude that all substitutes have a potential to disturb coagulation. Tromboelastography belongs between the most accurate ways to measure coagulation disturbances and has several substantial advantages compared to classic examination. Character and degree of the influence depends on quantity, velocity of administration and type of used solution.

Negative fluid balance in patients with abdominal compartment syndrome--case reports

Abdominal compartment syndrome (ACS) is defined as a sustained increase of intra-abdominal pressure (IAP) above 20 mmHg followed by the development of organ dysfunction. Treatment of ACS is still a question to be discussed and surgical decompression is usually preferred. According to recent data, massive crystalloid resuscitation of shock plays a key role in the development of secondary ACS in trauma patients. As mentioned previously, a high volume of infused crystalloids and a positive fluid balance were associated with ACS development in trauma patients as well as in septic patients. Moreover, we observed that a treatment strategy based on the achievement of a negative fluid balance resulted in a dramatic decrease in IAP and an improvement in haemodynamics and ventilation. This approach has been indicated as an interesting option for non-surgical treatment, with a caution that such intervention may exacerbate gut hypoperfusion. In this report we present two patients with secondary ACS development following abdominal surgery in which the achievement of a negative fluid balance showed a similar effect. Moreover, the fluid removal procedure also seemed to be associated with an improvement in splanchnic perfusion, as measured by gastric tonometry.

[Current view on the risks of artificial pulmonary ventilation]

There is no doubt that artificial ventilation of lungs seems to be proven as life-saving manoeuvre, whereas a growing amount of evidence is presented and published recently that artificial ventilation cause damage to patient by so far unexplained mechanism--by conversion of mechanical stress to biochemical signals inducing local and systemic inflammatory response, which is wide spreading and causing multiple organ dysfunction syndrome (MODS). Higher mortality of patients with acute lung injury on MODS rather than acute respiratory failure itself can be explained just by these findings. The article is brief summary of recent opinions of mechanism of ventilator induced lung and systemic injury. There is also evidence that the process of implementation of these finding into clinical practice is exceedingly slow.

[Intraabdominal hypertension at intensive care units]

Intraabdominal hypertension is frequently observed both in surgical and non-surgical patients hospitalised at intensive care units. This clinical syndrome of multifactorial etiology is characterised by increased intraabdominal tension with subsequent development of organ dysfunctions. It is reflected in impaired cardiovascular, pulmonary, renal, splanchnic and neurological functions which improve after the abdominal decompression. Patients with intraabdominal hypertension can be relatively easily identified by measuring tension in the bladder the primary purpose of which is early detection of clinically less severe stages and also the detection of the most sever forms of abdominal compartment syndrome. The objective of subsequent surgical or conservative treatment is to prevent organ dysfunction and subsequent multi-organ failure.

[Contribution and selected risks of blood transfusion]

AIM

Overview of recent knowledge about risks and benefits of blood transfusion.

TYPE OF STUDY

Review article.

SETTING

Department of Anaesthesiology and Intensive Care, University Hospital, Ostrava.

METHODS

Summary of previously published data.

CONCLUSION

Transfusion of blood and blood products remains controversial in clinical practice. Neither indication and timing nor benefit of this procedure is clearly determined. Previously often reported complications as blood-group incompatibility and infection are less frequent now, and new transfusion's side effects as TRIM (transfusion-related immunomodulation) and TRALI (transfusion-related lung injury) are reported with growing evidence. This risk (often underestimated in the past) is discussed in the article, and compared with blood transfusion benefits. Either restrictive or more open approach to blood transfusion are supported as well as criticised by different groups of clinicians and "good clinical practice" definition remains open for the future.

[Intraoperative correction of low cardiac output back to its physiological values improves the postoperative progress in patients undergoing extensive intraabdominal surgical procedures]

Perioperative optimalization of haemodynamics is associated with improved post-operative development, as presented in most published studies. This study has confirmed that intra-operative correction of cardiac output back to it's physiological level is associated with improved post-operative course in the group of patients undergoing major elective intraabdominal surgery. Statistically significant decreasing of post-operative complications (4.7% vs 17.7%), decreased length of stay (LOS) in the ICU by 33% and decreased LOS in the hospital by 24% was recorded. Interpretation of the study could be limited by using non-indexed cardiac output values and higher female presentation in the group of patients (although statistically not significant).

A syndrome of hypotonia, psychomotor retardation, seizures, delayed and dysharmonic skeletal maturation, and congenital fibre type disproportion

Three unrelated Puerto Rican boys, ranging in age from 3 to 4 years, had marked, central, non-progressive hypotonia, chronic constipation, severe psychomotor retardation, seizures or abnormal electroencephalograph or both, abnormal dermatoglyphics, delayed bone age, dysharmonic skeletal maturation, and preponderance and larger size of type 2 muscle fibres. Additional findings included narrow, high arched palate, prominent nasal root, long philtrum, distended abdomen, and drooling from open mouth. Two of the three patients also had undescended testes, hypertelorism, and tapered fingers. Birth weight, postnatal physical growth, and head size were average. Family and gestational histories and laboratory evaluations were normal. The combination of features observed in the three boys appears to be distinct and to represent a new syndrome.