Transesophageal echocardiography: clinical indications and applications

Left atrial appendage thrombus with severe mitral stenosis: Responders and non-responders to anticoagulation

INTRODUCTION AND OBJECTIVE

Mitral stenosis (MS) is one of the most frequently observed valvular heart lesions in developing countries and is due to different etiologies. The effects of anticoagulation in different types of left atrial appendage (LAA) are unknown. The current study aimed to determine the resolution of LAA thrombus on transesophageal echocardiography (TEE) after three months of optimal anticoagulation in patients with different types of LAA at baseline cardiac computed tomography of patients with severe MS.

METHODS

This prospective cohort study observed the frequency of LAA thrombus resolution after three months of anticoagulation therapy in patients with severe MS. The response rate in different morphologies of LAA and locations was also assessed. Thrombus resolution after three months of warfarin therapy was assessed on repeat TEE.

RESULTS

A total of 88 patients were included, mean age 37.95±11.87 years. Repeat TEE showed thrombus resolution in only 27.3% of patients. The rate of thrombus resolution was 8/12 (66.7%), 4/28 (14.3%), 8/36 (22.2%), and 4/12 (33.3%) for patients with cactus, cauliflower, chicken wing, and windsock LAA type, respectively. The resolution rate was 0/12 (0%), 4/44 (9.1%), and 20/32 (62.5%) for patients with thrombus in the base, body, and tip of the LAA, respectively.

CONCLUSION

The cactus type of LAA morphology and thrombus at the LAA tip responded well to three months of anticoagulation, however, patients with thrombus in the LAA base and body and cauliflower and chicken wing morphology were non-responders and could benefit from early referral for surgical management.

General Anesthesia Versus Local Anesthesia in Patients Undergoing Transcatheter Aortic Valve Replacement: An Updated Meta-Analysis and Systematic Review

OBJECTIVES

For patients with aortic stenosis, transcatheter aortic valve replacement (TAVR) offers a less invasive treatment modality than conventional surgical valve replacement. Although the surgery is performed traditionally under general anesthesia (GA), recent studies have described success with TAVR using local anesthesia (LA) and/or conscious sedation. The study authors performed a pairwise meta-analysis to compare the clinical outcomes of TAVR based on operative anesthesia management.

DESIGN

A random effects pairwise meta-analysis via the Mantel-Haenszel method.

SETTING

Not applicable, as this is a meta-analysis.

PARTICIPANTS

No individual patient data were used.

INTERVENTIONS

Not applicable, as this is a meta-analysis.

MEASUREMENTS AND MAIN RESULTS

The authors comprehensively searched the PubMed, Embase, and Cochrane databases to identify studies comparing TAVR performed using LA or GA. Outcomes were pooled as risk ratios (RR) or standard mean differences (SMD) and their 95% CIs. The authors' pooled analysis included 14,388 patients from 40 studies (7,754 LA; 6,634 GA). Compared to GA TAVR, LA TAVR was associated with significantly lower rates of 30-day mortality (RR 0.69; p < 0.01) and stroke (RR 0.78; p = 0.02). Additionally, LA TAVR patients had lower rates of 30-day major and/or life-threatening bleeding (RR 0.64; p = 0.01), 30-day major vascular complications (RR 0.76; p = 0.02), and long-term mortality (RR 0.75; p = 0.009). No significant difference was seen between the 2 groups for a 30-day paravalvular leak (RR 0.88, p = 0.12).

CONCLUSIONS

Transcatheter aortic valve replacement performed using LA is associated with lower rates of adverse clinical outcomes, including 30-day mortality and stroke. No difference was seen between the 2 groups for a 30-day paravalvular leak. These results support the use of minimally invasive forms of TAVR without GA.

Complications Associated With Transesophageal Echocardiography in Transcatheter Structural Cardiac Interventions

BACKGROUND

Transesophageal echocardiograms (TEEs) performed during transcatheter structural cardiac interventions may result in greater complications than those performed in the nonoperative setting or even those performed during cardiac surgery. However, there are limited data on complications associated with TEE during these procedures. We evaluated the prevalence of major complications among these patients in the United States.

METHODS

A retrospective cohort study was conducted using an electronic health record database (TriNetX Research Network) from large academic medical centers across the United States for patients undergoing TEE during transcatheter structural interventions from January 2012 to January 2022. Using the American Society of Echocardiography-endorsed International Statistical Classification of Diseases and Related Health Problems Clinical Modifications (10th edition) codes, patients undergoing TEE during a transcatheter structural cardiac intervention, including transaortic, mitral or tricuspid valve repair, left atrial appendage occlusion, atrial septal defect closure, patent foramen ovale closure, and paravalvular leak repair, were identified. The primary outcome was major complications within 72 hours of the procedure (composite of bleeding and esophageal and upper respiratory tract injury). The secondary aim was the frequency of major complications, death, or cardiac arrest within 72 hours in patients who completed intraoperative TEE during surgical valve replacement.

RESULTS

Among 12,043 adult patients (mean age, 74 years old; 42% female) undergoing TEE for transcatheter structural cardiac interventions, 429 (3.6%) patients had a major complication. Complication frequency was higher in patients on anticoagulation or antiplatelet therapy compared with those not on therapy (3.9% vs 0.5%; risk ratio [RR] = 8.09, P < .001). Compared with those patients <65 years of age, patients ≥65 years of age had a higher frequency of major complications (3.9% vs 2.2%; RR = 1.75, P < .001). Complication frequency was similar among male and female patients (3.5% vs 3.7%; RR = 0.96, P = .67). Among 28,848 patients who completed surgical valve replacement with TEE guidance, 728 (2.5%) experienced a major complication.

CONCLUSIONS

This study found that more than 3% of patients undergoing TEE during transcatheter structural cardiac interventions have a major complication, which is more common among those on anticoagulant or antiplatelet therapy or who are elderly. With a shift of poor surgical candidates to less invasive percutaneous procedures, the future of TEE-guided procedures relies on comprehensive risk discussion and updating practices beyond conventional methods to minimize risk for TEE-related complications.

Cardiac Anesthesia Intraoperative Interpretation Accuracy of Transesophageal Echocardiograms: A Review of the Current Literature and Meta-Analysis

Background

In the United States, echocardiography is an essential component of the care of many cardiac patients. Recently, increased attention has been given to the accuracy of interpretation of cardiac-based procedures in different specialties, amongst them the field of cardiac anesthesiology and primary echocardiographers for transesophageal echocardiogram (TEE). The purpose of this study was to assess the TEE skills of cardiac anesthesiologists in comparison to primary echocardiographers, either radiologists or cardiologists. In this systematic review, we evaluated available current literature to identify if cardiac anesthesiologists interpret TEE procedures at an identical level to that of primary echocardiographers.

Methods

A PRISMA systematic review was utilized from PubMed from the years 1952-2022. A broad keyword search of "Cardiology Anesthesiology Echocardiogram" and "Echocardiography Anesthesiology" to identify the literature was used. From reviewing 1798 articles, there were a total of 9 studies included in our systematic review, 3 of which yielded quantitative data and 6 of which yielded qualitative data. The mean accuracy from each of these three qualitative studies was calculated and used to represent the overall accuracy of cardiac anesthesiologists.

Results

Through identified studies, a total of 8197 TEEs were interpreted by cardiac anesthesiologists with a concordance rate of 84% to the interpretations of primary echocardiographers. Cardiac anesthesiologists had a concordance rate of 83% when compared to radiologists. On the other hand, cardiac anesthesiologists and cardiologists had a concordance rate of 87% in one study and 79% in another study.

Conclusion

Based on these studies, cardiac anesthesiologists are shown to interpret TEEs similarly to that of primary echocardiographers. At this time, there is no gold standard to evaluate the accuracy of TEE readings. One way to address this is to individually assess the TEE interpretation of anesthesiologists and primary echocardiographers with a double-blind study.

Transesophageal echocardiography in the emergency department: A comprehensive guide for acquisition, implementation, and quality assurance

Echocardiography is an essential tool in emergency medicine, yielding valuable information for physicians that directly affects diagnostic and management strategies. Emergency department (ED) transesophageal echocardiography (TEE) is an increasingly common procedure performed in a variety of institutions, allowing for ongoing cardiac imaging during cardiopulmonary resuscitation as well as providing high-resolution assessment of both cardiac and aortic anatomy. However, despite the numerous benefits of ED TEE, the process of implementing this modality within a department is difficult because of unique process and cost considerations. This paper serves to provide an updated and in-depth description of these processes to assist with the initiation of such a program, including a detailed discussion of budgetary considerations, physician credentialing, and device use and maintenance protocols.

Learning curve for the acquisition of 20 standard two-dimensional images in advanced perioperative transesophageal echocardiography: a prospective observational study

BACKGROUND

Learning to perform intraoperative transesophageal echocardiography takes time and practice. We aimed to determine the cumulative success rate in the first 20 intraoperative transesophageal echocardiography cases performed by trainee anesthesiologists with no transesophageal echocardiography experience.

METHODS

This prospective observational study included nine anesthesiologists (four cardiovascular and thoracic anesthesia fellows and five short-course perioperative intraoperative transesophageal echocardiography trainees). Overall, 180 studies self-performed by the trainees were reviewed by certified reviewers. A study was considered successful when at least 15 qualified images were collected within 30 min. The cumulative success of each trainee was used as a surrogate of a basic two-dimensional intraoperative transesophageal echocardiography learning curve.

RESULTS

The participants comprised three male and six female anesthesiologists aged 29-43 years with 2-13 years of work experience. Most studies (146/180, 81.11%) were completed within 30 min, and the cumulative success rate was 70-90% (average 82.78 ± 6.71%). The average cumulative success rate in the short-course group (85 ± 7.07%) was higher than that in the official cardiovascular and thoracic fellow trainee group (80 ± 7.07%). The recommended caseload for a 80-100% success rate was 18-20 cases (95% confidence interval, 0.652-0.973). The CUSUM method analysis confirmed that the lower decision limit was crossed after 20 TEE studies among those achieved competence.

CONCLUSIONS

We recommended a 18-20 caseload for a target success rate of 80-100% in studies performed by trainees with no previous experience. Our findings will enable the development of programs to train anesthesiologists in intraoperative transesophageal echocardiography.

Practicability and Diagnostic Yield of One-Stop Stroke CT with Delayed-Phase Cardiac CT in Detecting Major Cardioembolic Sources of Acute Ischemic Stroke : A Proof of Concept Study

Purpose

Recurrent stroke is considered to increase the incidence of severe disability and death. For correct risk assessment and patient management it is essential to identify the origin of stroke at an early stage. Transthoracic echocardiography (TTE) is the initial standard of care for evaluating patients in whom a cardioembolic source of stroke (CES) is suspected but its diagnostic capability is limited. Transesophageal echocardiography (TEE) is considered as gold standard; however, this approach is time consuming, semi-invasive and not always feasible. We hypothesized that adding a delayed-phase cardiac computed tomography (cCT) to initial multimodal CT might represent a valid alternative to routine clinical echocardiographic work-up.

Material and Methods

Patients with suspected acute cardioembolic stroke verified by initial multimodal CT and subsequently examined with cCT were included. The cCT was evaluated for presence of major CES and compared to routine clinical echocardiographic work-up.

Results

In all, 102 patients with suspected acute CES underwent cCT. Among them 60 patients underwent routine work-up with echocardiography (50 TTE and only 10 TEE). By cCT 10/60 (16.7%) major CES were detected but only 4 (6.7%) were identified by echocardiography. All CES observed by echocardiography were also detected by cCT. In 8 of 36 patients in whom echocardiography was not performed cCT also revealed a major CES.

Conclusion

These preliminary results show the potential diagnostic yield of delayed-phase cCT to detect major CES and therefore could accelerate decision-making to prevent recurrence stroke. To confirm these results larger studies with TEE as the reference standard and also compared to TTE would be necessary.

Adaptive Neuro-Fuzzy Inference System Based Orientation Control of an Intra-operative Ultrasound Robot

Trans-esophageal echocardiography (TEE) is a miniatured intra-operative ultrasound system, widely used in routine diagnosis and interventional procedure monitoring, to assess cardiac structures and functions. As a way to assist the operation of TEE remotely, we have developed an add-on robotic system to actuate a commercial TEE probe. For the proposed robot, understanding the inverse kinematics (IK) which relates the probe pose to the joint parameters is the fundamental step towards automatic control of the system. Rather than using conventional numerical-based techniques which may have problems with speed, convergence, and stability when applying to the TEE robot, this paper explores a soft computing approach by constructing an Adaptive Neuro-Fuzzy Inference System (ANFIS) to learn from training data generated by the forward kinematics (FK) and then computing the inverse kinematics in order to control the orientation of the TEE probe. With 1900 training data over 40 epochs, the minimum training error for each joint parameter was found to be less than 0.1 degree. Validation using a separate data set has indicated that the maximum error was less than 0.3 degree for each joint parameter. It is therefore concluded that the ANFIS-based approach is an effective way, with acceptable accuracy, to compute the inverse kinematics of the TEE robot.

Comprehensive Ultrasound Assessment of the Craniocervical Circulation in Transient Global Amnesia

OBJECTIVES

Structural changes and metabolic stress have been reported on diffusion-weighted magnetic resonance imaging in the cornu ammonis 1 area of the hippocampus in patients with transient global amnesia (TGA), but a consensus on pathogenesis is still lacking. The aim of our study was to perform a comprehensive ultrasound analysis of the cerebrovascular circulation in our population of patients with TGA.

METHODS

One hundred patients with TGA and 50 age- and sex-matched control participants underwent ultrasound examinations of the cervicocranial circulation.

RESULTS

The most significant risk factor for TGA was arterial hypertension (P < .01). There were no significant atherosclerotic lesions on the large arteries of the neck (mean internal carotid artery stenosis ± SD, 28.7% ± 11.7%) or on the large intracerebral arteries (good structural and hemodynamic status; P > .05). Rarely detected microembolic signals or a right-left cardiopulmonary shunt excluded an emboligenic mechanism of TGA (P > .05). The internal jugular vein valves were incompetent in 54% of patients with TGA, and this condition was associated with an increased risk of TGA (odds ratio, 4.16; 95% confidence interval, 1.91-9.04). The mean values of the breath holding index and pulsatility index, as parameters of small-vessel function, were within normal ranges and without differences between the TGA and control groups (P > .05).

CONCLUSIONS

Our ultrasound examination did not detect significant structural atherosclerotic changes of cervicocranial arteries, and an emboligenic mechanism was excluded. Only a significant rise of blood pressure in TGA and significant valvular insufficiency of the internal jugular vein were established. New research should clarify whether these simultaneous functional circulatory changes have relevance for metabolic stress in the cornu ammonis of the hippocampus.

Management of bacteremia in patients living with cardiovascular implantable electronic devices

Cardiovascular implantable electronic devices (CIEDs) have become a critical component in management of patients with cardiac rhythm disturbances, heart failure, and prevention of sudden cardiac death. However, infection remains a major complication of CIED implantation and is associated with significant morbidity and mortality for device recipients. Early-onset CIED infections frequently originate from the generator pocket, secondary to device or pocket contamination at the time of implantation, and may progress to involve device leads or cardiac valves. However, hematogenous seeding of the device leads from a remote source of bacteremia is not infrequent in patients with late-onset CIED infections. Whereas CIED pocket infection can be diagnosed in the majority of cases based on physical findings at the pulse generator site, device lead infection may only manifest with fever and positive blood cultures. However, not every patient with a CIED and positive blood cultures has underlying CIED lead infection. Consequently, management of bacteremia in a CIED recipient without local signs of infection presents a significant challenge. The risk of underlying CIED lead infection in patients presenting with bacteremia depends on several factors, including the type of microorganism isolated in blood cultures, duration and source of bacteremia, type of CIED, and number of device-related procedures. These risk factors must be considered when making decisions regarding the need for further diagnostic imaging and whether to retain or remove the device. In this article, we review the published data regarding risk of CIED infection in patients presenting with bacteremia and propose an algorithm for appropriate evaluation and management.

Development and Implementation of a Quality Improvement Process for Echocardiographic Laboratory Accreditation

We describe our process for quality improvement (QI) for a 3-year accreditation cycle in echocardiography by the Intersocietal Accreditation Commission (IAC) for a large group practice. Echocardiographic laboratory accreditation by the IAC was introduced in 1996, which is not required but could impact reimbursement. To ensure high-quality patient care and community recognition as a facility committed to providing high-quality echocardiographic services, we applied for IAC accreditation in 2010. Currently, there is little published data regarding the IAC process to meet echocardiography standards. We describe our approach for developing a multicampus QI process for echocardiographic laboratory accreditation during the 3-year cycle of accreditation by the IAC. We developed a quarterly review assessing (1) the variability of the interpretations, (2) the quality of the examinations, (3) a correlation of echocardiographic studies with other imaging modalities, (4) the timely completion of reports, (5) procedure volume, (6) maintenance of Continuing Medical Education credits by faculty, and (7) meeting Appropriate Use Criteria. We developed and implemented a multicampus process for QI during the 3-year accreditation cycle by the IAC for Echocardiography. We documented both the process and the achievement of those metrics by the Echocardiography Laboratories at the Ochsner Medical Institutions. We found the QI process using IAC standards to be a continuous educational experience for our Echocardiography Laboratory physicians and staff. We offer our process as an example and guide for other echocardiography laboratories who wish to apply for such accreditation or reaccreditation.

Perioperative Echocardiography

Echocardiography has been utilized perioperatively since the 1970s and many studies have been conducted to prove its efficacy. Epicardiac echocardiography (EE) is the modality of choice when transesophageal echocardiography (TEE) is contraindicated or when aortic atherosclerosis is suspected. Perioperative TEE has shown to be an excellent tool in the operating room for assessment, diagnosis, surgical guidance, and outcome evaluation. Pediatric surgery has also shown better surgical outcomes for congenital disease states with the guidance of TEE. The cardiac Sonographer’s role in the operating room is a very important one because it involves operating the ultrasound machine and communicating image interpretations to surgeons in a timely and efficient manner. Cardiac Sonographers eager to progress in their careers can take advantage of this opportunity to enhance their clinical and educational qualifications. Technology is advancing quickly with the breakthrough of 3D and 4D TEE, where images are captured in real time, providing improved diagnoses and prognosis. This article discusses the evolution of echocardiography in the operating room and its future impact on perioperative evaluation, with attention paid to the role of cardiac Sonographers and the future clinical progression in their scope of practice.

The significance of the ultrasound diagnostics in evaluation of the emboligenic pathogenesis of transient ischemic attacks

The objective of this study was to examine the possibilities of ultrasound diagnostics in the evaluation of emboligenic pathogenesis of transient ischemic attacks (TIAs) and the frequency of specific origins of embolism. A total of 150 adult patients with TIA and 50 control patients, were examined by neurosonologic, echocardiographic and venous ultrasound examination. Emboligenic pathogenesis of TIA was established in 36.6% of patients. Microembolic signals were detected in 22.7% of the whole group, and 61.8% in emboligenic TIA subgroup. Artery-to-artery embolism from ulcerated plaque of the carotid arteries was found in 12.6% of patients, from the aortic arch atheroma in 3.3% and cardioembolism in 12.6% (atrial fibrillation 7.3%, atrial septal aneurysm 2%, mitral valve prolapse 2%, mechanical heart valve 0.7%, left atrium thrombus 0.7%). Paradoxic embolism with the patent foramen ovale was established in 6% of patients, and with the pulmonary right-to-left shunt in 2%. Correlation with controls showed significantly higher frequency of the ulcerated carotid plaque and frequency of microembolic signals in the TIA group (p < 0.05). The patients with potential sources of embolism had a greater risk of developing TIA than those without these sources.

Left ventricular assist devices: physiologic assessment using echocardiography for management and optimization

Left ventricular assist devices (LVAD) are being deployed increasingly in patients with severe left ventricular dysfunction and medically refractory congestive heart failure of any etiology. The United States Food and Drug Administration (FDA) recently approved the use of the Thoratec Heartmate II (Thoratec Corporation, Pleasanton, CA, USA) for outpatient use. Echocardiography is fundamental during each stage of patient management, pre-LVAD placement, during LVAD placement, for postoperative LVAD optimization and long-term follow-up. We present a pragmatic and systematic echocardiographic approach that serves as a guide for the management of left ventricular assist devices.

Cardiac workup of ischemic stroke

Stroke is the leading cause of disability in developed countries and the third cause of mortality. Up to 15-30% of ischemic strokes are caused by cardiac sources of emboli being associated with poor prognosis and high index of fatal recurrence. In order to establish an adequate preventive strategy it is crucial to identify the cause of the embolism. After a complete diagnostic workup up to 30% of strokes remain with an undetermined cause, and most of them are attributed to an embolic mechanism suggesting a cardiac origin.There is no consensus in the extent and optimal approach of cardiac workup of ischemic stroke. Clinical features along with brain imaging and the study of the cerebral vessels with ultrasonography or MRI/CT based angiography can identify other causes or lead to think about a possible cardioembolic origin.Atrial fibrillation is the most common cause of cardioembolic stroke. Identification of occult atrial fibrillation is essential. Baseline ECG, serial ECG('s), cardiac monitoring during the first 48 hours, and Holter monitoring have detection rates varying from 4 to 8% each separately. Extended cardiac monitoring with event loop recorders has shown higher rates of detection of paroxysmal atrial fibrillation.Cardiac imaging with echocardiography is necessary to identify structural sources of emboli. There is insufficient data to determine which is the optimal approach. Transthoracic echocardiography has an acceptable diagnostic yield in patients with heart disease but transesophageal echocardiography has a higher diagnostic yield and is necessary if no cardiac sources have been identified in patients with cryptogenic stroke with embolic mechanism.

Prevalence, characteristics, and outcomes of patients presenting with cardiogenic unilateral pulmonary edema

BACKGROUND

Cardiogenic unilateral pulmonary edema (UPE) is a rare entity, frequently leading to initial misdiagnosis. We sought to assess the prevalence of UPE and to determine its impact on prognosis compared with bilateral pulmonary edema.

METHODS AND RESULTS

We studied the characteristics and outcomes of patients admitted to our institution for cardiogenic pulmonary edema during an 8-year period. The study population included 869 consecutive patients. The prevalence of UPE was 2.1%: 16 right-sided UPE (89%) and 2 left-sided UPE (11%). In patients with UPE, blood pressure was significantly lower (P≤0.01), whereas noninvasive or invasive ventilation and catecholamines were used more frequently (P=0.0004 and P<0.0001, respectively). The prevalence of severe mitral regurgitation in patients with bilateral pulmonary edema and UPE was 6% and 100%, respectively (P<0.0001). In patients with UPE, use of antibiotic therapy and delay in treatment were significantly higher (P<0.0001 and P=0.003, respectively). In-hospital mortality was 9%: 39% for UPE versus 8% for bilateral pulmonary edema (odds ratio, 6.9; 95% confidence interval, 2.6 to 18; P<0.001). In multivariate analysis, unilateral location of pulmonary edema was independently related to death whatever the model used (adjusted odds ratio, 6.5; 95% confidence interval, 1.3 to 32; P=0.021 for model A; and adjusted odds ratio, 6.8; 95% confidence interval, 1.1 to 41; P=0.037 for model B).

CONCLUSIONS

Unilateral pulmonary edema represented 2.1% of cardiogenic pulmonary edema in our study, usually appeared as an opacity involving the right lung, and was always associated with severe mitral regurgitation. Unilateral pulmonary edema is related to an independent increased risk of mortality and should be promptly recognized to avoid delays in treatment.

Cardiac workup of ischemic stroke: can we improve our diagnostic yield?

BACKGROUND AND PURPOSE

Discovering potential cardiac sources of stroke is an important part of the urgent evaluation of the ischemic stroke patient as it often impacts treatment decisions that are essential for determining secondary stroke prevention strategies, yet the optimal approach to the cardiac workup of an ischemic stroke patient is not known.

METHODS

A review of the literature concerning the utility of cardiac rhythm monitoring (ECG, telemetry, Holter monitors, and event recorders) and structural imaging (transthoracic and transesophageal echocardiography) was performed.

RESULTS

Data supporting a definitive, optimal, and cost-effective approach are lacking, though some data suggest that appropriate patient selection can improve the diagnostic and therapeutic yield of rhythm monitoring and echocardiography in the evaluation of stroke etiology.

CONCLUSIONS

Based on available data, an algorithmic approach for the evaluation of patients with acute ischemic cerebrovascular events that takes into account therapeutic and diagnostic yield as well as cost-efficiency is proposed.

New design for an endoesophageal sector- based array for the treatment of atrial fibrillation: a parametric simulation study

Atrial fibrillation (AF) is the most frequent and sustained cardiac arrhythmia affecting humans. The electrical isolation by ablation of the pulmonary veins (PV) in the left atrium (LA) of the heart has proved to be an effective cure for the AF. The ablation consists mainly of the formation of a localized circumferential thermal coagulation of the cardiac tissue surrounding the PVs. In this article, a parametric study was carried out to establish an optimal configuration of endesophageal ultrasound phased arrays intended to treat the AF. The devices are spherical-surface sections truncated at 15 mm, with a depth of 4 mm, and they are cut in concentric-rings, each composed of independently driven sectors. The number of independent elements (N(e)) was minimized for different values of ratio of pressure amplitude of the secondary lobe over the main lobe (eta) of 0.35, 0.4, 0.45, and 0.5 inside a volume of interest (VOI). After assuming a Cartesian system with the origin in the center of the device, the VOI was defined as the prism enclosed by the coordinates (-12, 10, -9) mm and (12, 37, 9) mm. The VOI has its center at (0, 23.5, 0) mm and is large enough to contain all the targets identified in the Visible Human Project Male specimen. Operating at 1 MHz, eta and N(e)were calculated in function of the element size and focal length (F). Four devices for each value of eta were found. After keeping values of F and normalized dimensions of the independent elements in terms of wavelength, higher frequencies were considered: 1.25 MHz, 1.5 MHz, and 2 MHz. In total, 16 device configurations were obtained. Realistic modeling of lesion formation in the heart chamber showed that the 16 configurations were able to produce the typical lesion used to treat the AF while preserving surrounding structures. At higher frequencies, lower power was required, and a greater number of array elements was required. For an exposure of 5 s and a maximum temperature of 70 degrees C, the average (+/-s.d.) acoustical intensity at transducer surface varied from 22.3(+/-5.8) W/cm(2) for a device with F = 98 mm at 1 MHz to 5.8(+/-1.2) W/cm(2) for a device with F = 186 mm at 2 MHz, while requiring 319 and 2093 elements, respectively, and achieving values of eta of 0.5 and 0.41, respectively. For the intended application, the selected devices implied a better focusing when compared with more traditional planar 2-D arrays, while requiring less power and fewer independent elements.

Major complications related to the use of transesophageal echocardiography in cardiac surgery

OBJECTIVE

The purpose of this study was to determine the incidence of injury associated with transesophageal echocardiography (TEE injuries) in cardiac surgery.

DESIGN

Retrospective.

SETTING

University-affiliated hospitals.

PARTICIPANTS

Four thousand seven hundred eighty-four patients, 89% of all public hospital cardiac surgery patients in Victoria, from the Australasian Society of Cardiac and Thoracic Surgeons (ASCTS) database undergoing cardiac surgery with TEE between July 1, 2005, and June 30, 2007. Because ASCTS did not record TEE use before July 2005, it was assumed that 89% of an additional 11,719 cardiac surgery patients between July 2001 and June 2005 also had TEE.

INTERVENTIONS

The authors searched the ASCTS database for cardiac surgery patients who also had endoscopy and/or noncardiac surgery. The files of these patients were screened for possible esophageal or gastric tears or perforations. An expert panel determined likely TEE injuries.

MEASUREMENTS AND MAIN RESULTS

There were 6 TEE complications from July 1, 2005, to June 30, 2007 (13/10,000 patients). There were a further 8 TEE complications before June 30, 2005, an extrapolated overall rate of 9/10,000 TEE (95% confidence interval, 5-16/10,000). TEE complications were more frequent in patients more than 70 years old (relative risk [RR], 3.7; p = 0.03) and women (RR, 6.5; p < 0.001). Three patients with TEE injury died (2/10,000).

CONCLUSIONS

TEE is associated with an incidence of major injuries of about 1 per 1,000 patients, with older women having a much higher risk. TEE use in cardiac surgery should be evaluated in the light of practice guidelines and morbidity and mortality data and not considered routine.

Atrial Septal Defect and Atrial Fibrillation: The Known and Unknown

Atrial fibrillation (AF) is a common complication in patients with atrial septal defects (ASDs). The link between AF and ASD is fairly complex and entails modifications in electrophysiologic, contractile and structural properties, at the cellular and tissue level, of both atria, mainly due to chronic atrial stretch and dilation. Surgical repair or percutaneous closure of ASDs are equally effective in reducing mortality and symptoms but limited in preventing or curbing AF, unless combined with an arrhythmia-specific procedure. Transesophageal echocardiography (TEE) and intracardiac echocardiography (ICE) have improved the safety and success of the above procedures. Finally, clearer understanding of the pathophysiology of AF in patients with ASD (and CHF, in general) has led to target-specific advances in medical management.

Perioperative echocardiographic examination for ventricular assist device implantation

Ventricular assist devices (VADs) are systems for mechanical circulatory support of the patient with severe heart failure. Perioperative transesophageal echocardiography is a major component of patient management, and important for surgical and anesthetic decision making. In this review we present the rationale and available data for a comprehensive echocardiographic assessment of patients receiving a VAD. In addition to the standard examination, device-specific pre-, intra-, and postoperative considerations are essential to the echocardiographic evaluation. These include: (a) the pre-VAD insertion examination of the heart and large vessels to exclude significant aortic regurgitation, tricuspid regurgitation, mitral stenosis, patent foramen ovale, or other cardiac abnormality that could lead to right-to-left shunt after left VAD placement, intracardiac thrombi, ventricular scars, pulmonic regurgitation, pulmonary hypertension, pulmonary embolism, and atherosclerotic disease in the ascending aorta; and to assess right ventricular function; and (b) the post-VAD insertion examination of the device and reassessment of the heart and large vessels. The examination of the device aims to confirm completeness of device and heart deairing, cannulas alignment and patency, and competency of device valves using two-dimensional, and color, continuous and pulsed wave Doppler modalities. The goal for the heart examination after implantation should be to exclude aortic regurgitation, or an uncovered right-to-left shunt; and to assess right ventricular function, left ventricular unloading, and the effect of device settings on global heart function. The variety of VAD models with different basic and operation principles requires specific echocardiographic assessment targeted to the characteristics of the implanted device.

Importance of transesophageal echocardiography in the critically ill and injured patient

Echocardiography, particularly transesophageal echocardiography (TEE), is a vital diagnostic and monitoring imaging modality for the intensivist. The field of echocardiography spans different venues and pathologies, ranging from surface transthoracic echocardiography and portable hand-held echocardiography, to contrast echocardiography, stress echocardiography, and TEE, among others. Numerous investigations have proven the worth of echocardiography, especially TEE, in the critically ill and injured patient, changing lives with the identification of obvious and subtle cardiothoracic diseases. Because this powerful imaging tool is immediately available and portable, crucial delays in diagnosis are not commonplace; rather than echocardiography, TEE, specifically, should be (and is in some institutions) the standard of care and management in assisting the intensivist in diagnosis of a variety of maladies. The effect of TEE technology is quite formidable, and numerous investigations have borne this out. The therapeutic effect of TEE ranges from 10% to 69%, with the majority of investigations falling into the 60% to 65% range. The diagnostic yield of TEE is far greater, approaching 78%. This article will detail the importance of echocardiography, its efficacy, and its high-yield imaging capability, particularly when compared with other imaging modalities, even transthoracic echocardiography.

Circumferential lesion formation around the pulmonary veins in the left atrium with focused ultrasound using a 2D-array endoesophageal device: a numerical study

Atrial fibrillation (AF) is the most frequently sustained cardiac arrhythmia affecting humans. The electrical isolation by ablation of the pulmonary veins (PVs) in the left atrium (LA) of the heart has been proven as an effective cure of AF. The ablation consists mainly in the formation of a localized circumferential thermal coagulation of the cardiac tissue surrounding the PVs. In the present numerical study, the feasibility of producing the required circumferential lesion with an endoesophageal ultrasound probe is investigated. The probe operates at 1 MHz and consists of a 2D array with enough elements (114 x 20) to steer the acoustic field electronically in a volume comparable to the LA. Realistic anatomical conditions of the thorax were considered from the segmentation of histological images of the thorax. The cardiac muscle and the blood-filled cavities in the heart were identified and considered in the sound propagation and thermal models. The influence of different conditions of the thermal sinking in the LA chamber was also studied. The circumferential ablation of the PVs was achieved by the sum of individual lesions induced with the proposed device. Different scenarios of lesion formation were considered where ultrasound exposures (1, 2, 5 and 10 s) were combined with maximal peak temperatures (60, 70 and 80 degrees C). The results of this numerical study allowed identifying the limits and best conditions for controlled lesion formation in the LA using the proposed device. A controlled situation for the lesion formation surrounding the PVs was obtained when the targets were located within a distance from the device in the range of 26 +/- 7 mm. When combined with a maximal temperature of 70 degrees C and an exposure time between 5 and 10 s, this distance ensured preservation of the esophageal structures, controlled lesion formation and delivery of an acoustic intensity at the transducer surface that is compatible with existing materials. With a peak temperature of 70 degrees C, the device and setup presented here induced highly localized lesions with a lesion volume varying from 10 +/- 4 to 18 +/- 7 mm(3) for an ultrasound exposure between 5 and 10 s, respectively, while the intensity varied from 26 +/- 7 to 20 +/- 6 W cm(-2).

Esophageal dissection complicating transesophageal echocardiogram--the lesson to be learned: do not force the issue

Transesophageal echocardiogram is a very safe procedure, however, it is not devoid of complications. We report a case of esophageal dissection complicating transesophageal echocardiogram in a 52-year-old man who was treated conservatively. Moreover, we review briefly the complications of transesophageal echocardiogram.

Noninvasive transesophageal cardiac thermal ablation using a 2-D focused, ultrasound phased array: a simulation study

This simulation study proposes a noninvasive, transesophageal cardiac-thermal ablation using a planar ultrasound phased array (1 MHz, 60 x 10 mm2, 0.525 mm interelement spacing, 114 x 20 elements). Thirty-nine foci in cardiac muscle were defined at 20, 40, and 60-mm distances and at various angles from the transducer surface to simulate the accessible posterior left atrial wall through the esophageal wall window. The ultrasound pressure distribution and the resulting thermal effect in a volume of 60 x 80 x 80 mm3, including esophagus and cardiac muscle, were simulated for each focus. For 1, 10, and 20-s sonications with 60 degrees C and 70 degrees C peak temperatures in cardiac muscle and without thermal damage in esophageal wall, the transducer acoustic powers were 105-727, 28-117, 21-79 W and 151-1044, 40-167, 30-114 W, respectively. The simulated lesions (thermal dose in equivalent minutes at 43 degrees C > or = 240 minutes) at these foci had lengths of 1-6, 3-11, 3-13 mm and 3-15, 5-19, 6-23 mm, respectively, and widths of 1-4, 2-7, 3-9 mm and 3-9, 4-13, 4-17 mm, respectively. As a first step toward feasibility, controllable tissue coagulation in cardiac tissue without damage to the esophagus was demonstrated numerically.

An initial application of transesophageal Doppler echocardiography in experimental small animal models

This study examined whether an intracardiac echocardiography catheter could be used for transesophageal echocardiography (TEE) examinations in normal rats, and intraoperative TEE in small animal models of disease. The study used 30 Sprague-Dawley normal rats, 10 rats undergoing coronary artery ligation, and 10 rats with experimentally induced mitral regurgitation. The rats were anesthetized with isoflurane and intubated. An intracardiac echocardiographic catheter was inserted into the esophagus. M-mode, 2-dimensional, and Doppler studies were performed in multiple views. TEE probe insertions were successful in all animals. Intraoperative TEE was safely performed in the rat models of myocardial infarction or mitral regurgitation. Mitral regurgitation was well assessed using color Doppler and pulmonary venous flow. This study demonstrates that TEE (including intraoperative TEE) can be safely performed in rats using an intracardiac echocardiographic catheter. It provides a new approach to the assessment of cardiac function and valvular regurgitation in small animals.

Management of transient ischemic attack: 2005

Transient ischemic attack is a common presenting problem to clinicians. Historically, these events were defined by the resolution of new neurologic symptoms within a 24-h time-frame; however, recent data suggests that a 1-h time frame is more appropriate. New imaging techniques and clinical evidence suggests that transient ischemic attacks present a higher risk of impending stroke than previously thought. This has led to a redefinition of what constitutes an attack, and also to a focus on both earlier investigation and treatment of correctable causes. New antiplatelet agents are now available and pose a challenge as to how they should be prescribed. Carotid endarterectomy is the standard of care for a subset of transient ischemic attack patients with significant carotid stenosis. Carotid angioplasty and stenting are more recent developments that may further expand treatment options.

Look before you close: Atrial septal defect with undiagnosed partial anomalous pulmonary venous return

The growing and continued success of percutaneous closure of atrial defects is related to its high benefit-to-risk ratio in appropriately selected patients. The following case illustrates a previously undocumented danger, namely, the potential for incomplete correction. A thorough transesophageal examination performed at the time of the planned atrial defect closure suggested the presence of a partial anomalous pulmonary vein insertion, which was then appropriately documented and the incomplete closure was averted.

Evaluation and management of transient ischemic attack and minor cerebral infarction

After immediate intervention for cerebral infarction or transient ischemic attack (TIA), the primary goal is secondary prevention of future cerebral ischemia and prevention of complications related to the initial ischemic event. The goals of the diagnostic evaluation are to (1) determine potential contributing mechanisms (cardioembolic, large-vessel disease of the extracranial and intracranial vessels, small-vessel disease, coagulation defects, and cryptogenic), (2) identify contributing risk factors (hypertension, hyperlipidemia, tobacco use, diabetes), and (3) complete the evaluation in a cost-effective and safe manner. We provide a sequential approach to the diagnostic evaluation of cerebral infarction or TIA to optimize diagnostic yield of testing, minimize cost and potential harm to the patient, and provide information that will change management. This systematic approach focuses on 6 important questions: (1) Are the symptoms consistent with a cerebral infarction or TIA (versus nonischemic pathology)? (2) Where does the ischemic event localize? (3) What etiologies and mechanisms of cerebral infarction and TIA are possible? (4) What is the prevalence of each potential etiology? (5) What treatments are available for this etiology? (6) What tests and studies are useful to evaluate this etiology?

Transoesophageal Echocardiogram Identifying the Source of Endoleak After Combined Open/Endovascular Repair of a Type 3 Thoracoabdominal Aortic Aneurysm

Open repair of thoracic aortic aneurysms is associated with significant morbidity and mortality. The introduction of endovascular repair has reduced both the morbidity and mortality. However, endovascular stent repair can be complicated by endoleaks. We report here the successful treatment of a type 2 endoleak following endovascular repair of a thoracoabdominal aortic aneurysm, using transesophageal echocardiography to assist in the localization of the thoracic endoleak.