Optimizing transesophageal atrial pacing in mice to detect atrial fibrillation.

Mice are routinely used to investigate molecular mechanisms underlying the atrial fibrillation (AF) substrate. We sought to optimize transesophageal rapid atrial pacing (RAP) protocols for the detection of AF susceptibility in mouse models. Hypertensive and control C57Bl/6J mice were subjected to burst RAP at a fixed stimulus amplitude. The role of parasympathetic involvement in pacing-related atrioventricular (AV) block and AF was examined using an intraperitoneal injection of atropine. In a crossover study, burst and decremental RAP at twice diastolic threshold were compared for induction of AV block during pacing. The efficacy of burst and decremental RAP to elicit an AF phenotype was subsequently investigated in mice deficient in the lymphocyte adaptor protein (Lnk-/-) resulting in systemic inflammation, or the paired-like homeodomain-2 transcription factor (Pitx2+/-) as a positive control. When pacing at a fixed stimulus intensity, pacing-induced AV block with AF induction occurred frequently, so that there was no difference in AF burden between hypertensive and control mice. These effects were prevented by atropine administration, implicating parasympathetic activation due to ganglionic stimulation as the etiology. When mice with AV block during pacing were eliminated from the analysis, male Lnk-/- mice displayed an AF phenotype only during burst RAP compared with controls, whereas male Pitx2+/- mice showed AF susceptibility during burst and decremental RAP. Notably, Lnk-/- and Pitx2+/- females exhibited no AF phenotype. Our data support the conclusion that multiple parameters should be used to ascertain AF inducibility and facilitate reproducibility across models and studies.NEW & NOTEWORTHY Methods were developed to optimize transesophageal rapid atrial pacing (RAP) to detect AF susceptibility in new and established mouse models. High stimulus intensity and pacing rates caused parasympathetic stimulation, with pacing-induced AV block and excessive AF induction in normal mice. For a given model, pacing at twice TH enabled improved phenotype discrimination in a pacing mode and sex-specific manner. Transesophageal RAP should be individually optimized when developing a mouse model of AF.

McGRATH MAC video laryngoscope assistance during transesophageal echocardiography may reduce the risk of complications: a manikin study.

BACKGROUND: Although transesophageal echocardiography (TEE) is considered a relatively safe diagnostic monitoring method, blind probe insertion is associated with pharyngeal trauma. Through visual observation of the esophageal inlet with the McGRATH video laryngoscope, it may be possible to insert the TEE probe at an appropriate angle and prevent pharyngeal trauma. We conducted a manikin study to investigate whether the use of the McGRATH video laryngoscope for TEE probe insertion reduced the pressure on the posterior pharyngeal wall. METHODS: Twenty-seven junior (inexperienced group) and 10 senior (experienced group) anesthesiologists participated in this study. The TEE probe was inserted into an airway manikin in a blind fashion (blind group) or under visualization with the McGRATH (McGRATH group) video laryngoscope (three times each). A sealed bag filled with normal saline was placed on the back of the posterior pharyngeal wall of the manikin and connected to a patient monitoring system via a pressure transducer. We measured the internal bag pressure and approximated this value to the pressure on the posterior pharyngeal wall. RESULTS: The pressure on the posterior pharyngeal wall was significantly lower in the McGRATH group than in the blind group (p < 0.001) and was significantly reduced when the McGRATH was employed in both the inexperienced (p < 0.001) and experienced (p < 0.001) groups. CONCLUSIONS: These findings suggest that TEE probe insertion under the assistance of the McGRATH video laryngoscope can reduce the pressure on the posterior pharyngeal wall, regardless of the clinician's experience, and may inform clinical practice with the potential to reduce probe insertion-associated complication rates.

Contrast transesophageal three dimensional echocardiographic imaging for patent foramen ovale: a needful role?

We report a case of a 55-year-old male admitted for cardiogenic embolic ischemic stroke work up. A transesophageal (TE) echocardiography (E) with contrast study to rule out patent foramen ovale (PFO) was performed; two-dimensional (2D) analysis did not detect any bubbles passage during Valsalva manoeuvre in the standard 2D cross sectional planes; further real time three-dimensional (3D) TEE imaging revealed passage of bubbles in the left atrium (LA) by both real-time 3DTEE imaging and by the 2D unconventional cross-sectional planes allowed by 3DTEE imaging. Even though 2DTEE is considered to be the gold standard modality for diagnosing PFO, it has some limitations. It has never been reported about usefulness of 3DTEE in PFO imaging. Even in the presence of only a report, our case suggests that 3DE could have an additional value and will compliment 2D imaging in PFO assessment.

[New oropharyngeal double lumen cannula for sedation for transesophageal echocardiography: case series]. / Nova cânula orofaríongea de duplo lúmen para sedação em ecocardiografia transesofágica: série de casos.

INTRODUCTION: Currently, transesophageal echodopplercardiography (TEE) is frequently performed under sedation on an outpatient basis. Sedation is related with increase in incidents on airways. Bearing in mind this scenario, we developed a new double lumen oropharyngeal cannula aimed at keeping airway patency, in addition to reducing risks to patients during endoscopy procedures performed under sedation. The main objective of our study was to assess the incidence of oxygen desaturation in a series of cases of adult patients submitted to outpatient TEE exam, under sedation and using the oropharyngeal cannula. METHOD: Thirty patients under sedation with intravenous midazolam and propofol were assessed. After loss of consciousness, the cannula was placed and patients were maintained on spontaneous breathing. Oxygen saturation, capnometry, heart rate and non-invasive arterial blood pressure, in addition to subjective data: airway patency, handling of cannula insertion, and comfort of examiner were analyzed. RESULTS: The incidence of mild desaturation was 23.3%, and there was no severe desaturation in any of the cases. The insertion of the oropharyngeal cannula was considered easy for 29 patients (96.6%), and TEE probe handling was appropriate in 93.33% of exams performed. CONCLUSIONS: TEE exams under sedation aided by the double-lumen oropharyngeal cannula presented a low incidence of desaturation in patients assessed, and allowed analysis of expired CO2 during the exams.

A recurrent and transesophageal echocardiography-associated outbreak of extended-spectrum ß-lactamase-producing Enterobacter cloacae complex in cardiac surgery patients.

Background: We report a recurrent outbreak of postoperative infections with extended-spectrum ß-lactamase (ESBL)-producing E. cloacae complex in cardiac surgery patients, describe the outbreak investigation and highlight the infection control measures. Methods: Cases were defined as cardiac surgery patients in Ghent University Hospital who were not known preoperatively to carry ESBL-producing E. cloacae complex and who postoperatively had a positive culture for this multiresistant organism between May 2017 and January 2018. An epidemiological investigation, including a case-control study, and environmental investigation were conducted to identify the source of the outbreak. Clonal relatedness of ESBL-producing E. cloacae complex isolates collected from case patients was assessed using whole-genome sequencing-based studies. Results: Three separate outbreak episodes occurred over the course of 9 months. A total of 8, 4 and 6 patients met the case definition, respectively. All but one patients developed a clinical infection with ESBL-producing E. cloacae complex, most typically postoperative pneumonia. Overall mortality was 22% (4/18). Environmental cultures were negative, but epidemiological investigation pointed to transesophageal echocardiography (TEE) as the outbreak source. Of note, four TEE probes showed a similar pattern of damage, which very likely impeded adequate disinfection. The first and second outbreak episode were caused by the same clone, whereas a different strain was responsible for the third episode. Conclusions: Health professionals caring for cardiac surgery patients and infection control specialists should be aware of TEE as possible infection source. Caution must be exercised to prevent and detect damage of TEE probes.

Continual hemodynamic monitoring with a single-use transesophageal echocardiography probe in critically ill patients with shock: a randomized controlled clinical trial.

PURPOSE: Mortality in circulatory shock is high. Enhanced resolution of shock may improve outcomes. We aim to determine whether adding hemodynamic monitoring with continual transesophageal echocardiography (hTEE) to usual care accelerates resolution of hemodynamic instability. METHODS: 550 patients with circulatory shock were randomly assigned to four groups stratified using hTEE (hTEE vs usual care) and assessment frequency (minimum every 4 h vs 8 h). Primary outcome was time to resolution of hemodynamic instability, analyzed as intention-to-treat (ITT) analysis at day 6 and in a predefined secondary analysis at days 3 and 28. RESULTS: Of 550 randomized patients, 271 with hTEE and 274 patients with usual care were eligible and included in the ITT analysis. Time to resolution of hemodynamic instability did not differ within the first 6 days [hTEE vs usual care adjusted sub-hazard ratio (SHR) 1.20, 95% confidence interval (CI) 0.98-1.46, p = 0.067]. Time to resolution of hemodynamic instability during the 72 h of hTEE monitoring was shorter in patients with TEE (hTEE vs usual care SHR 1.26, 95% CI 1.02-1.55, p = 0.034). Assessment frequency had no influence. Time to resolution of clinical signs of hypoperfusion, duration of organ support, length of stay and mortality in the intensive care unit and hospital, and mortality at 28 days did not differ between groups. CONCLUSIONS: In critically ill patients with shock, hTEE monitoring or hemodynamic assessment frequency did not influence resolution of hemodynamic instability or mortality within the first 6 days. TRIAL REGISTRATION AND STATISTICAL ANALYSIS PLAN: ClinicalTrials.gov Identifier: NCT02048566.

Infections and outcomes after cardiac surgery-The impact of outbreaks traced to transesophageal echocardiography probes.

BACKGROUND: Infections are a frequent complication of cardiac surgery. The intraoperative use of transesophageal echocardiography (TEE) may be an underrecognized risk factor for post-operative infections. The aim of this study was to investigate infection rates and outcomes after cardiac surgery in a nationwide cohort, especially in relation to periods where surface damaged TEE probes were used. METHODS: This was a retrospective, observational study at Landspitali University Hospital. All consecutive cardiac surgery patients from 1 January 2013 to 31 December 2017 were included. Patients' charts were reviewed for evidence of infection, post-operative complications or death. RESULTS: During the study period, 973 patients underwent cardiac surgery at Landspitali and 198 (20.3%) developed a post-operative infection. The most common infections were: Pneumonia (9.1%), superficial surgical site (5.7%), bloodstream (2.8%) and deep sternal wound (1.7%). Risk factors for developing an infection included: The duration of procedure, age, insulin-dependent diabetes, EuroScore II, reoperation for bleeding and an operation in a period with a surface damaged TEE probe in use. Twenty-two patients were infected with a multidrug resistant strain of Klebsiella oxytoca, 10 patients with Pseudomonas aeruginosa and two patients developed endocarditis with Enterococcus faecalis. All three pathogens were cultured from the TEE probe in use at respective time, after decontamination. The 30-day mortality rate in the patient cohort was 3.2%. CONCLUSIONS: The intraoperative use of surface damaged TEE probes caused two serious infection outbreaks in patients after cardiac surgery. TEE probes need careful visual inspection during decontamination and probe sheaths are recommended.

Miniaturized Echocardiography in the Cardiac Intensive Care Unit.

Miniaturized transesophageal echocardiography has become more common in cardiac intensive care units. There are potential benefits to this mode of technology, many of which have been described in the literature. However, image acquisition and quality have been cited as being less optimal when compared to traditional transesophageal echocardiography. This review will discuss the current options available for miniaturized transesophageal echocardiography along with a literature review of this emerging assessment modality.

Determination of residual mass in left ventricle by intraoperative transesophageal echocardiography after a giant and floating left atrial myxoma resection / Determinação da massa residual em ventrículo esquerdo por ecocardiografia transesofágica intraoperatória após ressecção de mixoma gigante e flutuante em átrio esquerdo

Abstract Atrial myxoma is a benign tumor of the heart that occurs primarily in the left atrium. Floating or large left atrial myxomas frequently cause functional mitral stenosis, may also affect mitral valve structure and flow, and lead to mitral regurgitation. Systemic embolization occurs in around 30% of cases either from tumor fragmentation or complete tumor detachment hence it should be removed as soon as it is detected. Intraoperative transesophageal echocardiography has a vital importance in the surgery. After resection of myxoma, intraoperative transesophageal echocardiography must be performed to rule out residual mass. The case here reported is of a 48-year old female, who presented with giant and floating left atrial myxoma. Residue mass was detected with intraoperative transesophageal echocardiography in the left ventricle after the resection of myxoma. Subsequently, the residue mass was successfully removed. Complete resection must be required to prevent possible complications such as recurrence, embolization in atrial myxomas. Transesophageal echocardiography performed intraoperatively is vital importance to confirm that the myxoma is completely resected.

Resumo Mixoma atrial é um tumor benigno do coração que ocorre principalmente no átrio esquerdo. Os mixomas flutuantes ou grandes em átrio esquerdo com frequência causam estenose mitral funcional, podendo também afetar a estrutura e o fluxo da válvula mitral e levar à insuficiência mitral. A embolização sistêmica ocorre em cerca de 30% dos casos, quer pela fragmentação do tumor ou pelo desprendimento total do tumor; portanto, o tumor deve ser removido assim que detectado. A ecocardiografia transesofágica intraoperatória tem uma importância vital na cirurgia. Após a ressecção do mixoma, a ecocardiografia transesofágica intraoperatória deve ser feita para excluir a massa residual. O caso aqui relatado é o de uma paciente de 48 anos que apresentou um mixoma de átrio esquerdo gigante e flutuante. A massa residual foi detectada com ecocardiografia transesofágica intraoperatória no ventrículo esquerdo após a ressecção do mixoma. Posteriormente, a massa residual foi removida com sucesso. A ressecção completa é necessária para evitar possíveis complicações, como recorrência e embolização em mixomas atriais. A ecocardiografia transesofágica realizada no intraoperatório é de vital importância para confirmar a ressecção completa do mixoma.

Acoustic characterization of a miniature matrix transducer for pediatric 3D transesophageal echocardiography.

This paper presents the design, fabrication and characterization of a miniature PZT-on-CMOS matrix transducer for real-time pediatric 3-dimensional (3D) transesophageal echocardiography (TEE). This 3D TEE probe consists of a 32 × 32 array of PZT elements integrated on top of an Application Specific Integrated Circuit (ASIC). We propose a partitioned transmit/receive array architecture wherein the 8 × 8 transmitter elements, located at the centre of the array, are directly wired out and the remaining receive elements are grouped into 96 sub-arrays of 3 × 3 elements. The echoes received by these sub-groups are locally processed by micro-beamformer circuits in the ASIC that allow pre-steering up to ±37°. The PZT-on-CMOS matrix transducer has been characterized acoustically and has a centre frequency of 5.8 MHz, -6 dB bandwidth of 67%, a transmit efficiency of 6 kPa/V at 30 mm, and a receive dynamic range of 85 dB with minimum and maximum detectable pressures of 5 Pa and 84 kPa respectively. The properties are very suitable for a miniature pediatric real-time 3D TEE probe.

Mitral valve navigator. A new diagnostic tool for effective regurgitant orifice quantification in mitral regurgitation.

INTRODUCTION: Mitral regurgitation severity assessment is usually carried out using qualitative, semiquantitative, and quantitative parameters. The mitral valve navigation (MVN) tool allows to measure the mitral effective regurgitant orifice (MERO) from 3D echo datasets. Our aim was to validate the MVN as a new tool to quantify MERO. A secondary aim was to assess the intra- and interobserver variability. METHODS: This is a retrospective study in which consecutive subjects undergoing a transoesophageal echocardiogram for more than mild mitral regurgitation evaluation were included. MERO measurement obtained by means of 3D color Doppler was used as the gold standard method for comparison. In every patient, MERO was also obtained using the MVN tool. RESULTS: Fifty-nine consecutive patients were analyzed (47.5% female; mean age 50.8 years). Mitral regurgitation was moderate in 23 (39%) and severe in 36 (61%) patients. Forty patients (67.8%) had a primary and 19 (32.2%) a secondary mitral regurgitation. The intraclass correlation coefficient (ICC) between 3D color Doppler and MVN was excellent (ICC: 0.95; 95% CI: 0.82 to 0.98; P < 0.001) in the total group and for patients with primary and secondary mitral regurgitation. Intra- and interobserver agreements were also good. CONCLUSIONS: Mitral valve navigator shows an excellent accuracy for measuring MERO when the transoesophageal 3D color Doppler is used as the reference method, either primary or secondary mitral regurgitation. Intraobserver reproducibility and interobserver reproducibility are also excellent. These findings make this software a good alternative method to measure mitral regurgitation severity.

Fast Volumetric Imaging Using a Matrix Transesophageal Echocardiography Probe with Partitioned Transmit-Receive Array.

We describe a 3-D multiline parallel beamforming scheme for real-time volumetric ultrasound imaging using a prototype matrix transesophageal echocardiography probe with diagonally diced elements and separated transmit and receive arrays. The elements in the smaller rectangular transmit array are directly wired to the ultrasound system. The elements of the larger square receive aperture are grouped in 4 × 4-element sub-arrays by micro-beamforming in an application-specific integrated circuit. We propose a beamforming sequence with 85 transmit-receive events that exhibits good performance for a volume sector of 60°â€¯× 60°. The beamforming is validated using Field II simulations, phantom measurements and in vivo imaging. The proposed parallel beamforming achieves volume rates up to 59 Hz and produces good-quality images by angle-weighted combination of overlapping sub-volumes. Point spread function, contrast ratio and contrast-to-noise ratio in the phantom experiment closely match those of the simulation. In vivo 3-D imaging at 22-Hz volume rate in a healthy adult pig clearly visualized the cardiac structures, including valve motion.

Usefulness of echocardiographic-fluoroscopic fusion imaging in children with congenital heart disease.

BACKGROUND: Transoesophageal echocardiography (TOE) has become indispensable in the catheterization laboratory in the guidance of some percutaneous interventions, as a complementary imaging technique to fluoroscopy. However, the two imaging modalities are presented separately and differently, making interpretation of the anatomical spatial relationships complicated. EchoNavigator® (Philips Healthcare, Best, the Netherlands) is an innovative software package, enabling fusion of fluoroscopic and echocardiographic images on the same screen. AIMS: To assess the feasibility of EchoNavigator® in the guidance of interventional procedures, and to present our initial clinical experience with this software. METHODS: Children with congenital heart disease who underwent interventional catheterization needing guidance with TOE from December 2015 to December 2017 were included. TOE was realized using a X7-2t TOE probe (Philips Healthcare) connected to an echocardiographic system (EPIC™; Philips Healthcare, Andover, MA). Fluoroscopy was realized using the Allura Xper FD/10 system (Philips Healthcare). Image fusion was attempted in all patients using EchoNavigator®. Markers were positioned on the target zone on echocardiographic images, and projected onto the merged screen. RESULTS: Fifty-one children were included (mean age, 8 years; mean weight, 25kg). Thirty-six patients underwent atrial septal defect closure, 10 ventricular septal defect closure, three aortic valve dilatation and two right ventricular outflow tract revalvulation. Image fusion was successfully obtained in all patients during all steps of the procedure. No complication related to the TOE probe was observed. Markers were successfully positioned in the all target zones, and were automatically projected onto the fusion screen. CONCLUSIONS: The EchoNavigator® system is feasible and safe in the guidance of interventional catheterization in children with congenital heart disease; it enables better appreciation of anatomical relationships and improves the confidence of the interventionist.