Loss of mutant p53 in HaCaT keratinocytes promotes cadmium-induced keratin 17 expression and cell death

BACKGROUND

Cadmium exposure induces dermatotoxicity and epidermal barrier disruption and leads to the development of various pathologies. HaCaT cells are immortalized human keratinocytes that are widely used as alternatives to primary human keratinocytes, particularly for evaluating cadmium toxicity. HaCaT cells bear two gain-of-function (GOF) mutations in the TP53 gene, which strongly affect p53 function. Mutant forms of p53 are known to correlate with increased resistance to various stimuli, including exposure to cytotoxic substances. In addition, keratin 17 (KRT17) was recently shown to be highly expressed in HaCaT cells in response to genotoxic stress. Moreover, p53 is a direct transcriptional repressor of KRT17. However, the impact of TP53 mutations in HaCaT cells on the regulation of cell death and keratin 17 expression is unclear. In this study, we aimed to evaluate the impact of p53 on the response to Cd-induced cytotoxicity.

METHODS AND RESULTS

Employing the MTT assay and Annexin V/propidium iodide staining, we demonstrated that knockout of TP53 leads to a decrease in the sensitivity of HaCaT cells to the cytotoxic effects of cadmium. Specifically, HaCaT cells with TP53 knockout (TP53 KO HaCaT) exhibited cell death at a cadmium concentration of 10 μM or higher, whereas wild-type cells displayed cell death at a concentration of 30 μM. Furthermore, apoptotic cells were consistently detected in TP53 KO HaCaT cells upon exposure to low concentrations of cadmium (10 and 20 μM) but not in wild-type cells. Our findings also indicate that cadmium cytotoxicity is mediated by reactive oxygen species (ROS), which were significantly increased only in TP53 knockout cells treated with 30 μM cadmium. An examination of proteomic data revealed that TP53 knockout in HaCaT cells resulted in the upregulation of proteins involved in the regulation of apoptosis, redox systems, and DNA repair. Moreover, RT‒qPCR and immunoblotting showed that cadmium toxicity leads to dose-dependent induction of keratin 17 in p53-deficient cells but not in wild-type cells.

CONCLUSIONS

The connection between mutant p53 in HaCaT keratinocytes and increased resistance to cadmium toxicity was demonstrated for the first time. Proteomic profiling revealed that TP53 knockout in HaCaT cells led to the activation of apoptosis regulatory circuits, redox systems, and DNA repair. In addition, our data support the involvement of keratin 17 in the regulation of DNA repair and cell death. Apparently, the induction of keratin 17 is p53-independent but may be inhibited by mutant p53.

Exploring the Functions of Mutant p53 through TP53 Knockout in HaCaT Keratinocytes

Approximately 50% of tumors carry mutations in TP53; thus, evaluation of the features of mutant p53 is crucial to understanding the mechanisms underlying cell transformation and tumor progression. HaCaT keratinocytes represent a valuable model for research in this area since they are considered normal, although they bear two gain-of-function mutations in TP53. In the present study, transcriptomic and proteomic profiling were employed to examine the functions of mutant p53 and to investigate the impact of its complete abolishment. Our findings indicate that CRISPR-mediated TP53 knockout results in significant changes at the transcriptomic and proteomic levels. The knockout of TP53 significantly increased the migration rate and altered the expression of genes associated with invasion, migration, and EMT but suppressed the epidermal differentiation program. These outcomes suggest that, despite being dysfunctional, p53 may still possess oncosuppressive functions. However, despite being considered normal keratinocytes, HaCaT cells exhibit oncogenic properties.

Evaluation of Cd-induced cytotoxicity in primary human keratinocytes

An increasing number of studies have investigated the effects of Cd on human health. Cd-induced dermatotoxicity is an important field of research, but numerous studies have focused on the effects of Cd on the human skin. Moreover, most studies have been performed using HaCaT cells but not primary keratinocytes. In this study, we provide the results describing the cytotoxic effects of Cd exposure on primary human epidermal keratinocytes obtained from different donors. The subtoxic concentration of cadmium chloride was determined via MTT assay, and transcriptomic analysis of the cells exposed to this concentration (25 µM) was performed. As in HaCaT cells, Cd exposure resulted in increased ROS levels, cell cycle arrest, and induction of apoptosis. In addition, we report that exposure to Cd affects zinc and copper homeostasis, induces metallothionein expression, and activates various signaling pathways, including Nrf2, NF-kB, TRAIL, and PI3K. Cd induces the secretion of various cytokines (IL-1, IL-6, IL-10, and PGE2) and upregulates the expression of several cytokeratins, such as KRT6B, KRT6C, KRT16, and KRT17. The results provide a better understanding of the mechanisms of cadmium-induced cytotoxicity and its effect on human epidermal skin cells.

The effect of TLR3 priming conditions on MSC immunosuppressive properties

BACKGROUND

Mesenchymal stromal cells (MSCs) have regenerative and immunomodulatory properties, making them suitable for cell therapy. Toll-like receptors (TLRs) in MSCs respond to viral load by secreting immunosuppressive or proinflammatory molecules. The expression of anti-inflammatory molecules in MSCs can be altered by the concentration and duration of exposure to the TLR3 ligand polyinosinic-polycytidylic acid (poly(I:C)). This study aimed to optimize the preconditioning of MSCs with poly(I:C) to increase immunosuppressive effects and to identify MSCs with activated TLR3 (prMSCs).

METHODS

Flow cytometry and histochemical staining were used to analyze MSCs for immunophenotype and differentiation potential. MSCs were exposed to poly(I:C) at 1 and 10 μg/mL for 1, 3, and 24 h, followed by determination of the expression of IDO1, WARS1, PD-L1, TSG-6, and PTGES2 and PGE2 secretion. MSCs and prMSCs were cocultured with intact (J-) and activated (J+) Jurkat T cells. The proportion of proliferating and apoptotic J+ and J- cells, IL-10 secretion, and IL-2 production after cocultivation with MSCs and prMSCs were measured. Liquid chromatography-mass spectrometry and bioinformatics analysis identified proteins linked to TLR3 activation in MSCs.

RESULTS

Poly(I:C) at 10 μg/mL during a 3-h incubation caused the highest expression of immunosuppression markers in MSCs. Activation of prMSCs caused a 18% decrease in proliferation and a one-third increase in apoptotic J+ cells compared to intact MSCs. Cocultures of prMSCs and Jurkat cells had increased IL-10 and decreased IL-2 in the conditioned medium. A proteomic study of MSCs and prMSCs identified 53 proteins with altered expression. Filtering the dataset with Gene Ontology and Reactome Pathway revealed that poly(I:C)-induced proteins activate the antiviral response. Protein‒protein interactions by String in prMSCs revealed that the antiviral response and IFN I signaling circuits were more active than in native MSCs. prMSCs expressed more cell adhesion proteins (ICAM-I and Galectin-3), PARP14, PSMB8, USP18, and GBP4, which may explain their anti-inflammatory effects on Jurkat cells.

CONCLUSIONS

TLR3 activation in MSCs is dependent on exposure time and poly(I:C) concentration. The maximum expression of immunosuppressive molecules was observed with 10 µg/mL poly(I:C) for 3-h preconditioning. This priming protocol for MSCs enhances the immunosuppressive effects of prMSCs on T cells.

EVALUATION OF THE EFFECTIVENESS OF PHYSIOTHERAPEUTIC INTERVENTIONS IN THE TREATMENT OF THORACIC PAІN IN PATIENTS WITH THORACIC OSTEOCHONDROSIS

The purpose of the study is to improve the results of complex restorative treatment of patients with pain syndrome in osteochondrosis of the thoracic spine. The study was conducted on the basis of the Rehabilitation Department of the State Institution "ITO NAMSU" in Kiev (from 2020 to 2022). The study involved 150 patients with pain in the thoracic spine, who were treated in the rehabilitation department. The mean age of the patients was 44.7±1.5 years. The average duration of the disease was 10.2±0.3 years, treatment - 13.5±1.0 days. Evaluation of treatment results using the Visual Analogue Scale of pain (Visual Analogue Scale) and electromyography on DIGITAL M - TEST was carried out 14 days after the program of physiotherapy interventions. The developed program of rehabilitation interventions included the use of myofascial release of the thoracic spine, physical exercises, breathing exercises during the myofascial release of the thoracic spine. The analysis of the obtained results showed that after the rehabilitation measures with the use of myofascial release, there was a statistically significant decrease in the level of pain in the group of examined patients (before PT - 4.87±0.47 cm, after PT - 1.17±0.26*) * (x±S), (p<0.01), which allows us to conclude that the program of physiotherapy interventions is effective. The use of myofascial release in the complex of physiotherapeutic interventions improves the quality of life and saves patients from thoracic paіn caused by degenerative changes in the spine in the short term.

Comparative proteoinformatics revealed the essentials of SDS impact on HaCaT keratinocytes

There is no direct evidence supporting that SDS is a carcinogen, so to investigate this fact, we used HaCaT keratinocytes as a model of human epidermal cells. To reveal the candidate proteins and/or pathways characterizing the SDS impact on HaCaT, we proposed comparative proteoinformatics pipeline. For protein extraction, the performance of two sample preparation protocols was assessed: 0.2% SDS-based solubilization combined with the 1DE-gel concentration (Protocol 1) and osmotic shock (Protocol 2). As a result, in SDS-exposed HaCaT cells, Protocol 1 revealed 54 differentially expressed proteins (DEPs) involved in the disease of cellular proliferation (DOID:14566), whereas Protocol 2 found 45 DEPs of the same disease ID. The 'skin cancer' term was a single significant COSMIC term for Protocol 1 DEPs, including those involved in double-strand break repair pathway (BIR, GO:0000727). Considerable upregulation of BIR-associated proteins MCM3, MCM6, and MCM7 was detected. The eightfold increase in MCM6 level was verified by reverse transcription qPCR. Thus, Protocol 1 demonstrated high effectiveness in terms of the total number and sensitivity of MS identifications in HaCaT cell line proteomic analysis. The utility of Protocol 1 was confirmed by the revealed upregulation of cancer-associated MCM6 in HaCaT keratinocytes induced by non-toxic concentration of SDS. Data are available via ProteomeXchange with identifier PXD035202.

PHYSICAL THERAPY PROGRAM IN THE TREATMENT OF OSTEOARTHROSIS IN PATIENTS WITH OBESITY

Osteoarthrosis is a family of pathological processes with multifactorial etiopathogenesis, including genetic, molecular and environmental factors, in particular, biomechanical stress. Obesity is one of the significant risk factors for osteoarthritis, increasing the risk of its development. The purpose of the research is to study the features of compiling an algorithm of physiotherapeutic interventions for patients suffering from knee osteoarthritis and obesity. The research was conducted during 2019-2020 on the basis of the sports & fitness center «Dog & Grand CrossFit», Kiev, and in department of radio-induced general and endocrinological pathology of the Scientific Center of Radiation Medicine of the National Academy of Medical Sciences of Ukraine. 68 women with a personal history of: obesity 1-2 degree and arthrosis of the knee joints of the 1st stage were examined. During the study two groups were formed: control (CG, n=33) and the main group (MG, n=35). After сonducting the program of physiotherapeutic interventions in patients with MG and CG, the average statistical indicators of the available range of movements during flexion of the affected limb in the knee joint improved significantly and amounted: MG 121,8±4,70 and CG 110,4±4,30. The difference between the indices in the post-rehabilitation period between the patients of MG and CG is statistically significant. Changes in BMI made it possible to note the clinical effect of weight loss in the main group, in contrast to the dynamics of BMI of KG, which was to a lesser extent. During repeated survey the dynamics of a decrease in the level of pain in MG was more than in CG( MG - 0,64±0,15 points, CG - 2,7±0,5 points). Prevention of obesity by means of individual physiotherapy programs, including lifestyle changes, dietary counseling and kinesiotherapy, is the first step in treating patients with obesity and osteoarthritis of the knee.

Specifics of seasonal settlements in Moscow region according to the results of the Moscow Mayor elections 2018

Most of seasonal second homes of Russians are located in gardeners’ associations being a component of modern urbanized settlement. Now in Russia there are about 14 million garden plots, which are used at least by 40 million people. The greatest number of gardeners’ associations (over 11.5 thousand) is registered in Moscow region. Their seasonal population can make up to 4 million people, and some of them live in summer homes most of the year, thus turning them actually into places of permanent residence. This trend is supported by new laws regulating registration of gardeners’ associations. An indirect indicator of this is the number of voters who took part in the Moscow Mayor elections in suburban areas in September 2018. The importance of summer residents increases with the distance from the capital, and more than half of the «suburban» polling stations were located in the middle and far suburbs, or even in neighboring regions. The very fact of the organization of suburban polling stations indicates a change in the role of gardeners’ associations, which become an impetus of socio-economic development in Moscow region. This is especially important for areas that have lost major industries. It is clearly seen on the example of the «gardeners’ conglomerates» that have emerged on the former peat mine lands in Moscow region, where seasonal population now exceeds the number of permanent residents of the surrounding settlements. «Gardeners’ conglomerates» can provide local population with jobs that is particularly important for marginal areas of the region.

Trends in anesthesiology research: a machine learning approach to theme discovery and summarization

Objectives

Traditionally, summarization of research themes and trends within a given discipline was accomplished by manual review of scientific works in the field. However, with the ushering in of the age of “big data,” new methods for discovery of such information become necessary as traditional techniques become increasingly difficult to apply due to the exponential growth of document repositories. Our objectives are to develop a pipeline for unsupervised theme extraction and summarization of thematic trends in document repositories, and to test it by applying it to a specific domain.

Methods

To that end, we detail a pipeline, which utilizes machine learning and natural language processing for unsupervised theme extraction, and a novel method for summarization of thematic trends, and network mapping for visualization of thematic relations. We then apply this pipeline to a collection of anesthesiology abstracts.

Results

We demonstrate how this pipeline enables discovery of major themes and temporal trends in anesthesiology research and facilitates document classification and corpus exploration.

Discussion

The relation of prevalent topics and extracted trends to recent events in both anesthesiology, and healthcare in general, demonstrates the pipeline’s utility. Furthermore, the agreement between the unsupervised thematic grouping and human-assigned classification validates the pipeline’s accuracy and demonstrates another potential use.

Conclusion

The described pipeline enables summarization and exploration of large document repositories, facilitates classification, aids in trend identification. A more robust and user-friendly interface will facilitate the expansion of this methodology to other domains. This will be the focus of future work for our group.

EliIE: An open-source information extraction system for clinical trial eligibility criteria

Objective

To develop an open-source information extraction system called Eligibility Criteria Information Extraction (EliIE) for parsing and formalizing free-text clinical research eligibility criteria (EC) following Observational Medical Outcomes Partnership Common Data Model (OMOP CDM) version 5.0.

Materials and Methods

EliIE parses EC in 4 steps: (1) clinical entity and attribute recognition, (2) negation detection, (3) relation extraction, and (4) concept normalization and output structuring. Informaticians and domain experts were recruited to design an annotation guideline and generate a training corpus of annotated EC for 230 Alzheimer's clinical trials, which were represented as queries against the OMOP CDM and included 8008 entities, 3550 attributes, and 3529 relations. A sequence labeling-based method was developed for automatic entity and attribute recognition. Negation detection was supported by NegEx and a set of predefined rules. Relation extraction was achieved by a support vector machine classifier. We further performed terminology-based concept normalization and output structuring.

Results

In task-specific evaluations, the best F1 score for entity recognition was 0.79, and for relation extraction was 0.89. The accuracy of negation detection was 0.94. The overall accuracy for query formalization was 0.71 in an end-to-end evaluation.

Conclusions

This study presents EliIE, an OMOP CDM-based information extraction system for automatic structuring and formalization of free-text EC. According to our evaluation, machine learning-based EliIE outperforms existing systems and shows promise to improve.

An Interoperable Similarity-based Cohort Identification Method Using the OMOP Common Data Model version 5.0

Cohort identification for clinical studies tends to be laborious, time-consuming, and expensive. Developing automated or semi-automated methods for cohort identification is one of the "holy grails" in the field of biomedical informatics. We propose a high-throughput similarity-based cohort identification algorithm by applying numerical abstractions on Electronic Health Records (EHR) data. We implement this algorithm using the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM), which enables sites using this standardized EHR data representation to avail this algorithm with minimum effort for local implementation. We validate its performance for a retrospective cohort identification task on six clinical trials conducted at the Columbia University Medical Center. Our algorithm achieves an average Area Under the Curve (AUC) of 0.966 and an average Precision at 5 of 0.983. This interoperable method promises to achieve efficient cohort identification in EHR databases. We discuss suitable applications of our method and its limitations and propose warranted future work.

From expert-derived user needs to user-perceived ease of use and usefulness: a two-phase mixed-methods evaluation framework

Underspecified user needs and frequent lack of a gold standard reference are typical barriers to technology evaluation. To address this problem, this paper presents a two-phase evaluation framework involving usability experts (phase 1) and end-users (phase 2). In phase 1, a cross-system functionality alignment between expert-derived user needs and system functions was performed to inform the choice of "the best available" comparison system to enable a cognitive walkthrough in phase 1 and a comparative effectiveness evaluation in phase 2. During phase 2, five quantitative and qualitative evaluation methods are mixed to assess usability: time-motion analysis, software log, questionnaires - System Usability Scale and the Unified Theory of Acceptance of Use of Technology, think-aloud protocols, and unstructured interviews. Each method contributes data for a unique measure (e.g., time motion analysis contributes task-completion-time; software log contributes action transition frequency). The measures are triangulated to yield complementary insights regarding user-perceived ease-of-use, functionality integration, anxiety during use, and workflow impact. To illustrate its use, we applied this framework in a formative evaluation of a software called Integrated Model for Patient Care and Clinical Trials (IMPACT). We conclude that this mixed-methods evaluation framework enables an integrated assessment of user needs satisfaction and user-perceived usefulness and usability of a novel design. This evaluation framework effectively bridges the gap between co-evolving user needs and technology designs during iterative prototyping and is particularly useful when it is difficult for users to articulate their needs for technology support due to the lack of a baseline.

Hidden in plain sight: bias towards sick patients when sampling patients with sufficient electronic health record data for research

Background

To demonstrate that subject selection based on sufficient laboratory results and medication orders in electronic health records can be biased towards sick patients.

Methods

Using electronic health record data from 10,000 patients who received anesthetic services at a major metropolitan tertiary care academic medical center, an affiliated hospital for women and children, and an affiliated urban primary care hospital, the correlation between patient health status and counts of days with laboratory results or medication orders, as indicated by the American Society of Anesthesiologists Physical Status Classification (ASA Class), was assessed with a Negative Binomial Regression model.

Results

Higher ASA Class was associated with more points of data: compared to ASA Class 1 patients, ASA Class 4 patients had 5.05 times the number of days with laboratory results and 6.85 times the number of days with medication orders, controlling for age, sex, emergency status, admission type, primary diagnosis, and procedure.

Conclusions

Imposing data sufficiency requirements for subject selection allows researchers to minimize missing data when reusing electronic health records for research, but introduces a bias towards the selection of sicker patients. We demonstrated the relationship between patient health and quantity of data, which may result in a systematic bias towards the selection of sicker patients for research studies and limit the external validity of research conducted using electronic health record data. Additionally, we discovered other variables (i.e., admission status, age, emergency classification, procedure, and diagnosis) that independently affect data sufficiency.

Clustering clinical trials with similar eligibility criteria features

OBJECTIVES

To automatically identify and cluster clinical trials with similar eligibility features.

METHODS

Using the public repository ClinicalTrials.gov as the data source, we extracted semantic features from the eligibility criteria text of all clinical trials and constructed a trial-feature matrix. We calculated the pairwise similarities for all clinical trials based on their eligibility features. For all trials, by selecting one trial as the center each time, we identified trials whose similarities to the central trial were greater than or equal to a predefined threshold and constructed center-based clusters. Then we identified unique trial sets with distinctive trial membership compositions from center-based clusters by disregarding their structural information.

RESULTS

From the 145,745 clinical trials on ClinicalTrials.gov, we extracted 5,508,491 semantic features. Of these, 459,936 were unique and 160,951 were shared by at least one pair of trials. Crowdsourcing the cluster evaluation using Amazon Mechanical Turk (MTurk), we identified the optimal similarity threshold, 0.9. Using this threshold, we generated 8806 center-based clusters. Evaluation of a sample of the clusters by MTurk resulted in a mean score 4.331±0.796 on a scale of 1-5 (5 indicating "strongly agree that the trials in the cluster are similar").

CONCLUSIONS

We contribute an automated approach to clustering clinical trials with similar eligibility features. This approach can be potentially useful for investigating knowledge reuse patterns in clinical trial eligibility criteria designs and for improving clinical trial recruitment. We also contribute an effective crowdsourcing method for evaluating informatics interventions.

Fluorescent optical fiber sensors for cell viability monitoring

A new simple method for non-invasive cell culture viability monitoring based on vital fluorescent stains is introduced, and its efficiency for long-term experiments on cells is demonstrated. In contrast to common methods for cell viability control, which are usually either destructive (like flow-type counters or dead cells coloring and counting), or hardly quantitative like fluorescent microscopy, the method described is automated, does not require the removal of cells from their growth area and is sensitive enough to deal with as low as tens of cells.

Short-term reduction in intrinsic heart rate during biventricular pacing after cardiac surgery: a substudy of a randomized clinical trial

BACKGROUND

The Biventricular Pacing After Cardiac Surgery trial investigates hemodynamics of temporary pacing in selected patients at risk of left ventricular dysfunction. This trial demonstrates improved hemodynamics during optimized biventricular pacing compared with atrial pacing at the same heart rate 1 and 2 hours after bypass and reduced vasoactive-inotropic score over the first 4 hours after bypass. However, this advantage of biventricular versus atrial pacing disappears 12 to 24 hours later. We hypothesized that changes in intrinsic heart rate can explain variable effects of atrial pacing in this setting.

METHODS

Heart rate, mean arterial pressure, cardiac output, and medications depressing heart rate were analyzed in patients randomized to continuous biventricular pacing (n = 16) or standard of care (n = 18).

RESULTS

During 30-second testing periods without pacing, intrinsic heart rate was lower in the paced group 12 to 24 hours after bypass (76.5 ± 17.5 vs 91.7 ± 13.0 beats per minute; P = .040) but not 1 or 2 hours after bypass. Cardiac output (4.4 ± 1.2 vs 3.6 ± 1.9 L/min; P = .054) and stroke volume (53 ± 2 vs 42 ± 2 mL; P = .051) increased overnight in the paced group. Vasoactive medication doses were not different between groups, whereas dexmedetomidine administration was prolonged over postoperative hours 12 to 24 in the paced group (793 ± 528 vs 478 ± 295 minutes; P = .013).

CONCLUSIONS

These observations suggest that hemodynamic benefits of biventricular pacing 12 to 24 hours after cardiopulmonary bypass lead to withdrawal of sympathetic drive and decreased intrinsic heart rate. Depression of intrinsic rate increases the apparent benefit of atrial pacing in the chronically paced group but not in the control group. Additional study is needed to define clinical benefits of these effects.

Temporary biventricular pacing decreases the vasoactive-inotropic score after cardiac surgery: a substudy of a randomized clinical trial

OBJECTIVE

Vasoactive medications improve hemodynamics after cardiac surgery but are associated with high metabolic and arrhythmic burdens. The vasoactive-inotropic score was developed to quantify vasoactive and inotropic support after cardiac surgery in pediatric patients but may be useful in adults as well. Accordingly, we examined the time course of this score in a substudy of the Biventricular Pacing After Cardiac Surgery trial. We hypothesized that the score would be lower in patients randomized to biventricular pacing.

METHODS

Fifty patients selected for increased risk of left ventricular dysfunction after cardiac surgery and randomized to temporary biventricular pacing or standard of care (no pacing) after cardiopulmonary bypass were studied in a clinical trial between April 2007 and June 2011. Vasoactive agents were assessed after cardiopulmonary bypass, after sternal closure, and 0 to 7 hours after admission to the intensive care unit.

RESULTS

Over the initial 3 collection points after cardiopulmonary bypass (mean duration, 131 minutes), the mean vasoactive-inotropic score decreased in the biventricular pacing group from 12.0 ± 1.5 to 10.5 ± 2.0 and increased in the standard of care group from 12.5 ± 1.9 to 15.5 ± 2.9. By using a linear mixed-effects model, the slopes of the time courses were significantly different (P = .02) and remained so for the first hour in the intensive care unit. However, the difference was no longer significant beyond this point (P = .26).

CONCLUSIONS

The vasoactive-inotropic score decreases in patients undergoing temporary biventricular pacing in the early postoperative period. Future studies are required to assess the impact of this effect on arrhythmogenesis, morbidity, mortality, and hospital costs.

Effect of atrioventricular conduction prolongation on optimization of paced atrioventricular delay for biventricular pacing after cardiac surgery

OBJECTIVES

Atrioventricular conduction prolongation (AVCP) in cardiac pacing is measurable and results primarily from delayed atrial conduction. Noninvasive methods for measuring atrial conduction are lacking. Accordingly, AVCP was used to estimate atrial conduction and investigate its role on the paced atrioventricular delay (pAVD) during biventricular pacing (BiVP) optimization.

DESIGN

Retrospective analysis of data collected as part of a randomized controlled study of temporary BiVP after cardiopulmonary bypass.

SETTING

Single-center study at university-affiliated tertiary care hospital.

PARTICIPANTS

Cardiac surgical patients at risk of left ventricular failure after cardiopulmonary bypass.

INTERVENTIONS

Temporary BiVP was optimized immediately after cardiopulmonary bypass. Vasoactive medication and fluid infusion rates were held constant during optimization.

MEASUREMENTS AND MAIN RESULTS

For each patient the AVCP and the pAVD producing the optimum (highest) cardiac output (OptCO) and mean arterial pressure (OptMAP) were determined. Patients were stratified into long- and short-AVCP groups. Overall AVCP (mean ± standard deviation) was 64 ± 28 ms. For the short-AVCP group (<64 ms, n = 3), AVCP, OptCO, and OptMAP were 40 ± 11, 120 ± 0, and 150 ± 30 ms, respectively, and for the long-AVCP group (>64 ms, n = 4), these same parameters were 89 ± 10, 218 ± 44, and 218 ± 29 ms. OptCO and OptMAP were significantly less in the short-AVCP group (p = 0.015 and p = 0.029, respectively).

CONCLUSIONS

AVCP varies widely after cardiopulmonary bypass, affecting optimum pAVD. Failure to correct for this can result in the selection of inappropriately short and potentially deleterious pAVDs, especially when nominal pAVD is used, causing BiVP to appear ineffective.

Hemodynamic stability during biventricular pacing after cardiopulmonary bypass

OBJECTIVE

To assess the stability of cardiac output, mean arterial pressure, and systemic vascular resistance during biventricular pacing (BiVP) optimization.

DESIGN

Substudy analysis of data collected as part of a randomized controlled study examining the effects of optimized temporary BiVP after cardiopulmonary bypass (CPB).

SETTING

A single-center study at a university-affiliated tertiary care hospital.

PARTICIPANTS

Cardiac surgery patients at risk of left ventricular failure after CPB.

INTERVENTIONS

BiVP was optimized immediately after CPB. Atrioventricular delay (7 unique settings) was optimized first, followed by the left ventricular pacing site (3 unique settings) and then the interventricular delay (9 unique settings). Each setting was tested twice for 10 seconds each time. Vasoactive medication and fluid infusion rates were held constant.

MEASUREMENTS AND MAIN RESULTS

Aortic flow velocity and radial artery pressure were digitized, recorded, and averaged over single respiratory cycles. Least squares and linear regression/Wilcoxon analyses were applied to the first 7 patients studied. Subsequently, curvilinear analysis was applied to 15 patients. Changes in mean arterial pressure and systemic vascular resistance were statistically insignificant or too small to be meaningful by least squares analysis. During interventricular synchrony optimization, cardiac output and mean arterial pressure decreased (mean changes -5.7% and -2.5%, respectively; with standard errors 2.3% and 1.5%, respectively), whereas SVR increased (mean change 3.1% with standard error 3.4%). Only the change in cardiac output was statistically significant (p = 0.043). Curvilinear fits to data for 15 patients demonstrated progressive hemodynamic stability over the total testing period.

CONCLUSION

BiVP optimization may be done safely in patients after CPB. With continuous monitoring of mean arterial pressure and cardiac output, the procedure results in no harmful hemodynamic perturbation.

Left ventricular pacing lead insertion via the coronary sinus cardioplegia cannula: a novel method for temporary biventricular pacing during reoperative cardiac surgery

OBJECTIVE

Temporary biventricular pacing to treat low output states after cardiac surgery is an active area of investigation. Reoperative cases are not studied due to adhesions, which preclude left ventricular mobilization to place epicardial pacing wires. In such patients, inserting a temporary left ventricular lead via the coronary sinus cardioplegia cannula may allow for biventricular pacing. We developed a novel technique for intraoperative left ventricular lead placement.

METHODS

Eight domestic pigs underwent median sternotomy and pericardiotomy. Temporary pacing wires were sewn to the right atrium and right ventricle. Complete heart block was induced by ethanol ablation of the atrioventricular node. A 13-French retrograde cardioplegia catheter was introduced via the right atrial free wall into the coronary sinus. A 6-French left ventricular pacing lead was inserted into the cardioplegia catheter and advanced into the coronary sinus during biventricular pacing until left ventricular capture was detected by electrocardiogram and arterial pressure monitoring. Left ventricular capture success rate and electrical performance were recorded during five placement attempts.

RESULTS

Left ventricular capture was achieved on 80% of insertion attempts. Left ventricular capture without diaphragmatic pacing was achieved in 7 pigs. Lead tip locations were mostly in lateral and posterior basal coronary vein branches. There were no arrhythmias, bleeding, or perforation associated with lead insertion.

CONCLUSIONS

Intraoperative biventricular pacing with a left ventricular pacing lead inserted via the coronary sinus cardioplegia cannula is feasible, using standard instrumentation and without requiring cardiac manipulation. This approach merits further study in patients undergoing reoperative cardiac surgery.

Optimized temporary biventricular pacing acutely improves intraoperative cardiac output after weaning from cardiopulmonary bypass: a substudy of a randomized clinical trial

OBJECTIVE

Permanent biventricular pacing benefits patients with heart failure and interventricular conduction delay, but the importance of pacing with and without optimization in patients at risk of low cardiac output after cardiac surgery is unknown. We hypothesized that pacing parameters independently affect cardiac output. Accordingly, we analyzed aortic flow measured with an electromagnetic flowmeter in patients at risk of low cardiac output during an ongoing randomized clinical trial of biventricular pacing (n = 11) versus standard of care (n = 9).

METHODS

A substudy was conducted in all 20 patients in both groups with stable pacing after coronary artery bypass grafting, valve surgery, or both. Ejection fraction averaged 33% ± 15%, and QRS duration was 116 ± 19 ms. Effects were measured within 1 hour of the conclusion of cardiopulmonary bypass. Atrioventricular delay (7 settings) and interventricular delay (9 settings) were optimized in random sequence.

RESULTS

Optimization of atrioventricular delay (171 ± 8 ms) at an interventricular delay of 0 ms increased flow by 14% versus the worst setting (111 ± 11 ms, P < .001) and 7% versus nominal atrioventricular delay (120 ms, P < .001). Interventricular delay optimization increased flow 10% versus the worst setting (P < .001) and 5% versus nominal interventricular delay (0 ms, P < .001). Optimized pacing increased cardiac output 13% versus atrial pacing at matched heart rate (5.5 ± 0.5 vs 4.9 ± 0.6 L/min, P = .003) and 10% versus sinus rhythm (5.0 ± 0.6 L/min, P = .019).

CONCLUSIONS

Temporary biventricular pacing increases intraoperative cardiac output in patients with left ventricular dysfunction undergoing cardiac surgery. Atrioventricular and interventricular delay optimization maximizes this benefit.