An adaptable microreactor to investigate the influence of interfaces on Pseudomonas aeruginosa biofilm growth

Biofilms are ubiquitous and notoriously difficult to eradicate and control, complicating human infections and industrial and agricultural biofouling. However, most of the study had used the biofilm model that attached to solid surface and developed in liquid submerged environments which generally have neglected the impact of interfaces. In our study, a reusable dual-chamber microreactor with interchangeable porous membranes was developed to establish multiple growth interfaces for biofilm culture and test. Protocol for culturing Pseudomonas aeruginosa (PAO1) on the air–liquid interface (ALI) and liquid–liquid interface (LLI) under static environmental conditions for 48 h was optimized using this novel device. This study shows that LLI model biofilms are more susceptible to physical disruption compared to ALI model biofilm. SEM images revealed a unique “dome-shaped” microcolonies morphological feature, which is more distinct on ALI biofilms than LLI. Furthermore, the study showed that ALI and LLI biofilms produced a similar amount of extracellular polymeric substances (EPS). As differences in biofilm structure and properties may lead to different outcomes when using the same eradication approaches, the antimicrobial effect of an antibiotic, ciprofloxacin (CIP), was chosen to test the susceptibility of a 48-h-old P. aeruginosa biofilms grown on ALI and LLI. Our results show that the minimum biofilm eradication concentration (MBEC) of 6-h CIP exposure for ALI and LLI biofilms is significantly different, which are 400 μg/mL and 200 μg/mL, respectively. These results highlight the importance of growth interface when developing more targeted biofilm management strategies, and our novel device provides a promising tool that enables manipulation of realistic biofilm growth. Key points • A novel dual-chamber microreactor device that enables the establishment of different interfaces for biofilm culture has been developed. • ALI model biofilms and LLI model biofilms show differences in resistance to physical disruption and antibiotic susceptibility.

Dual Atrial Rhythms: A Case Report Of An Unusual Cause Of Pacemaker Syndrome

Background Atrial dissociation (AD) is described as the existence of two simultaneous electrically isolated atrial rhythms. Theoretically, detection of dual atrial rhythms with a sufficiently high rate by pacemaker can lead to automatic mode switching and associated pacemaker syndrome. Such a clinical observation has not been reported before in the literature. Case Summary An 87-year-old female with Ebstein’s anomaly status post tricuspid valve annuloplasty and tricuspid valve replacement and a dual chamber pacemaker presented with congestive heart failure one week after undergoing atrial lead revision. Interrogation of her dual chamber pacemaker revealed two atrial rhythms: sinus or atrial-paced rhythm and electrically isolated atrial tachycardia (AT). Sensing of both atrial rhythms by the pacemaker led to automatic mode switching, which manifested as ventricular paced rhythm with retrograde P waves on electrocardiogram (ECG). Adjusting the atrial lead sensitivity to a level higher than the sensing amplitude of AT restored atrial paced and ventricular sensed rhythm, which resulted in resolution of heart failure symptoms. Discussion Regardless of the cause of AD, there must be electrical insulation between the two rhythms for their independent coexistence in the atria. AD can lead to pacemaker syndrome from automatic mode switching. If the sensing amplitude during sinus rhythm is significantly larger than that of AT, adjusting the atrial lead sensitivity would solve the issue, as in the present case. Otherwise, atrial lead revision, pharmacotherapy or AT ablation should be considered.

The Usefulness of Dual Channel Elastomeric Pump for Intravenous Patient-Controlled Analgesia in Geriatrics: A Randomized, Double-Blind, Prospective Study

Background: Intravenous patient-controlled analgesia (IV-PCA) is well applied in postoperative period. However, determining an appropriate opioid dose was difficult. A previous study suggested the usefulness of variable-rate feedback infusion. In this study, we used a dual-channel elastomeric infusion pump to provide changes in PCA infusion rate by pain feedback.Methods: 90 patients of ASA I-III and 65 to 79 years undergoing orthopedic surgery were participated in the study. All patients were applied a dual-chamber PCA. Patients were randomly allocated into treatment group (Group D; PCA drugs were divided into both chambers.) or control group (Group C; PCA drugs were contained only in the constant flow chamber, but normal saline was contained in the adjustable flow chamber.) The primary outcome was the amount of fentanyl consumption via PCA bolus. The secondary outcome variables were pain score, total fentanyl consumption, rescue analgesic use, patient satisfaction, recovery scores and adverse events including postoperative nausea and vomiting (PONV).Results: Group D showed decreased fentanyl consumption in PCA bolus. Moreover, group D showed in a decrease in rescue analgesic use and better patient satisfaction. The incidence of PONV was much higher in group C. There was no difference in other adverse events.Conclusions: We showed the usefulness of dual chamber IV-PCA to change the flow rate to the pain feedback without any complication. Our results suggested noble implications that may improve existing IV-PCA equipment.Clinical trial registration: The study registered at UMIN clinical trial registry (registered date: 05/03/2020, registration number: UMIN000039702).

Successful Identification of and Discrimination Between Atrial and Ventricular Arrhythmia with the Aid of Pacing and Defibrillator Devices

The presence of supraventricular tachycardia is the leading cause of inappropriate shock in ICD recipients, and it can be a significant cause of morbidity, psychological distress and worsened clinical outcome. Modern pacing and ICD systems offer a number of discriminators that are integrated into algorithms to differentiate sustained ventricular tachycardia from supraventricular tachycardia. These algorithms can be adapted and optimised for each individual patient to ensure that only those arrhythmias that need treatment through the use of an ICD, are actually treated. This review summarises the single- and dual-chamber discriminators that can be used in the detection and classification of tachyarrhythmias.

309 Upgrading from a dual-chamber pacemaker to a cardiac resynchronization therapy defibrillator in situs inversus totalis with dextrocardia following mitral valve replacement and tricuspid annuloplasty using a left-sided approach

A 71-year-old female patient was referred to our centre to upgrade a dual-chamber pacemaker to a cardiac resynchronization therapy defibrillator (CRT-D) following the detection of worsened systolic function (ejection fraction: 25–30%) via transthoracic echocardiography. The patient had situs inversus totalis with dextrocardia. She had undergone mitral valve replacement and tricuspid annuloplasty in July 2019, with a concomitant left upper pulmonary lobectomy for neoplasm, detected at cardiac tomography incidentally. In January 2020, we performed an upgrade of the preexisting device to a CRT-D system because the patient developed heart failure, reduction in systolic function, and numerous nonsustained ventricular tachycardias. The right ventricular lead that had been previously implanted was extracted. To facilitate the intervention, we decided to flip the fluoroscopic image, obtained with a right-anterior oblique view, by 180 °C (right–left), creating the optical impression of a levocardial position.

557 His bundle pacing: how to troubleshoot the implantation of a ventricular back-up lead

Aims Interest in permanent His bundle pacing (HBP) as a means of both preventing pacing-induced cardiomyopathy and providing physiological resynchronization by normalization of His-Purkinje activation is constantly growing. Current devices are not specifically designed for HBP, which gives rise to programming challenges. To evaluate the critical troubleshooting HBP options in patients with permanent atrial fibrillation (AF) and variable degree of atrio-ventricular block (AVB) who receive HBP through a lead connected to the atrial port, and an additional ventricular ‘backup’. Methods and results Between December 2018 and July 2021, 156 consecutive patients with indication for pacing underwent HBP. Among these, 37 had permanent AF with documented symptomatic pauses. Fourteen of them received a dual-chamber device which was used to place a backup right ventricle (RV) lead; in this scenario, the His lead is implanted in the right atrial (RA) port, the RV lead in the RV port. Depending on the presence of an additional left ventricle (LV) lead, either a dual-chamber and a CRT device can be used. In this context, the events marked as atrial sensed (As) or paced (Ap) are indeed ventricular, so that sensing is more complex. A clinical scenario is atrial activity oversensed on the His channel (As) leading to RV dyssynchronous pacing in the ventricular safety pacing (VSP) window. A second one is intrinsic QRS undersensing causing inappropriate His pacing. The interplay of intrinsic ventricular activity (rate, signal amplitude, and slew rate on both the His and the ventricular channel) and of the HV interval may be of key importance to troubleshoot As–Vp (atrial sensed–ventricular paced) (Figure 1A) as well as Vs–Ab (ventricular sensed–atrial blanking period) sequences (Figure 1B). Changing sensitivity and sensing configuration may help to fix these issues. DVI(R) mode programming may indeed prove safer than DDD(R) in the setting of preserved intrinsic activity or in the event of intermittent His capture loss. Paced AV delay should be programmed slightly longer than H-V+QRS duration to avoid unnecessary RV pacing with pseudo-fusion (too short) (Figure 2A) and possibly R/T events (too long). Stability of H-V interval and of QRS duration must be verified at each device follow-up by decremental His pacing to ensure consistent sensitivity of the ventricular signal beyond stable His capture, that may be challenged by infra-Hisian block (Figure 2B). Conclusions Owing to the absence of HBP-specific devices, HBP shall be made safe and effective by careful troubleshooting, consisting of sensitivity setting, paced AV interval and mode programming. 557 Figure