Transoesophageal pulsed doppler echocardiography

Resuscitative Transesophageal Echocardiography in Critical Care

The use of focused critical care echocardiography, diagnostic modality aimed to provide immediate and actionable information, represents a core competency of contemporary intensive care medicine. Resuscitative transesophageal echocardiography (TEE) is a focused, goal-directed examination performed at the point of care, for the rapid evaluation of critically ill patients in whom transthoracic images are either logistically untenable, inadequate, or unobtainable. Some of the applications of TEE in the management of critically ill patients include the evaluation of patients in shock and cardiac arrest, the assessment of trauma patients, and the guidance of several endovascular procedures. Due to the indwelling nature of the transducer, TEE can provide consistently high-quality images and allows for continuous monitoring during hemodynamic interventions, making it ideally suited for the evaluation of critically ill patients. In this article, we review the evolving landscape of resuscitative TEE, discuss the rationale, supporting evidence, safety, and training for the use of this modality in critical care settings. We address the transdisciplinary evolution of TEE and the practical aspects of its implementation in emergency and critical care settings.

A concise history of echocardiography: timeline, pioneers, and landmark publications

Echocardiography is less than 70 years old, and many major advances have occurred within living memory, but already some pioneering contributions may be overlooked. In order to consider what circumstances have been common to the most successful innovations, we have studied and here provide a timeline and summary of the most important developments in transthoracic and transoesophageal ultrasound imaging and Doppler techniques, as well as in intravascular ultrasound and imaging in paediatric cardiology. The entries are linked to a comprehensive list of first publications and to a collection of first-hand historical accounts published by early investigators. Review of the original manuscripts highlights that it is difficult to establish unequivocal precedence for many new imaging methods, since engineers were often working independently but simultaneously on similar problems. Many individuals who are prominently linked with particular developments were not the first in their field. Developments in echocardiography have been highly dependent on technological advances, and most likely to be successful when engineers and clinicians were able to collaborate with open exchange between centres and disciplines. As with many other new medical technologies, initial responses were sceptical and introduction into clinical practice required persistence and substantial energy from the first adopters. Current developments involve advances in software as much as in equipment, and progress will depend on continuing collaborations between engineers and clinical scientists, for example to identify unmet needs and to investigate the clinical impact of particular imaging approaches.

EUS and related technologies for the diagnosis and treatment of pancreatic disease: research gaps and opportunities-Summary of a National Institute of Diabetes and Digestive and Kidney Diseases workshop

A workshop was sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases to address the research gaps and opportunities in pancreatic EUS. The event occurred on July 26, 2017 in 4 sessions: (1) benign pancreatic diseases, (2) high-risk pancreatic diseases, (3) diagnostic and therapeutics, and (4) new technologies. The current state of knowledge was reviewed, with identification of numerous gaps in knowledge and research needs. Common themes included the need for large multicenter consortia of various pancreatic diseases to facilitate meaningful research of these entities; to standardize EUS features of different pancreatic disorders, the technique of sampling pancreatic lesions, and the performance of various therapeutic EUS procedures; and to identify high-risk disease early at the cellular level before macroscopic disease develops. The need for specialized tools and accessories to enable the safe and effective performance of therapeutic EUS procedures also was discussed.

Continuous measurement of intracardiac and pulmonary blood flow velocities with transesophageal pulsed Doppler echocardiography: technique and initial clinical experience

Pulsed Doppler techniques have become well established adjuncts to conventional echocardiography in the noninvasive diagnosis of various cardiac malfunctions. Disadvantages of the transthoracic approach, such as inaccessibility and instability of the probe position, limit the continuous application of pulsed Doppler echocardiography during surgery. This study presents a new technique using the transesophageal approach that combines pulsed Doppler measurements with two-dimensional echocardiographic imaging (TDE). The first intraoperative experience with this new enhancement to two-dimensional transesophageal echocardiography (TEE) showed that this relatively noninvasive technique is a safe method allowing constant monitoring of cardiac and pulmonary blood flow velocities. The simultaneous high-resolution two-dimensional imaging facilitates spatial orientation and placement of the sample volume, as well as continued control of the sampling location. The typical flow velocity patterns in standard TEE views are described. The mitral valve and pulmonary artery offer particularly favorable conditions for continuous high-quality TDE measurements. It is concluded that the new technique may further increase the value of TEE to clinicians in the perioperative period.

Assessment of transesophageal pulsed Doppler echocardiography in the detection of mitral regurgitation

The value of transesophageal pulsed Doppler echocardiography (PDE) was studied in six patients with competent mitral valve and in 12 patients with angiographically proved mild to moderately severe mitral regurgitation. The results were compared with those from the standard transthoracic method of investigation. The advantages of the esophageal over the transthoracic approach in the detection of mitral regurgitation are (1) absence of anatomic obstacles between the ultrasound transducer and the heart; (2) nearly parallel alignment of the ultrasound beam with the blood flow direction; (3) the use of high pulse repetition frequencies; and (4) detection of localized regurgitant jets by left atrial scanning. This results in a superior recording quality and greater sensitivity. Based on a specific systolic flow pattern in the time-interval histogram, mitral regurgitation was detected in all patients by the transesophageal technique (100% sensitivity), but in only 58% by the precordial approach. Thus, transesophageal pulsed Doppler echocardiography can accurately detect the presence of mitral regurgitation, particularly in cases of mild or moderate severity.

High speed rotating scanner for transesophageal cross-sectional echocardiography

In conventional cross-sectional echocardiography, the configuration of the chest or the presence of excessive chest wall tissue or air-containing lung often limits the resolution and field of view. To increase the diagnostic capability of cross-sectional echocardiography, a transesophageal ultrasonic high speed rotating scanner that can obtain cardiac images without hindrance from ribs, sternum and lung was developed. The scanner uses a single small transducer with a flexible shaft to permit easy swallowing by adults and mechanically scans ultrasonic beams within the esophagus. The small transducer in the esophagus is rotated through a full 360 degrees at a rate of 15 to 50 cycles/s, and cardiac images obtained through the esophageal wall are displayed on a cathode ray tube in real time. The transesophageal scanning technique was evaluated in more than 50 adult patients. Aside from some slight gagging, no serious complications were encountered. In all patients, high quality images of most portions of the heart were obtained. There was little difference in the image quality among various patients.

Transesophageal cross-sectional echocardiography

A transesophageal cardiac imaging system is described. This system employs hand-held mechanical sector and linear scanners each having a flexible tube and a small ultrasonic transducer contained within a small oil bag easily swallowed by adults. In the sector scanner, a small transducter in the esophagus rotates alternately and horizontal heart images are displayed. In the linear scanner, a small transducer in the esophagus moves up and down and vertical heart images are displayed. The system was evaluated in 31 adult subjects. In all subjects, stable high quality heart images were observed continuously from base to apex as the transducer was being withdrawn or entire heart images were observed at the level of the atrioventricular valves. In vertical scans, the bifurcation of the pulmonary artery could be observed clearly. There was little difference in the image quality among subjects.