Innovations in transesophageal echocardiographic imaging

Over the last three decades, the continuing development of transesophageal echocardiography (TEE) has represented a major advance in our ability to visualize cardiovascular structures with ultrasound. TEE serves as a valuable complement to transthoracic echocardiography (TTE) by allowing: images to be obtained with less attenuation from structures such as the lung, muscle, bone, and soft tissue; high resolution visualization of structures not well seen by TTE, such as left atrial appendage, descending thoracic aorta, and prosthetic heart valves; and assessment of hemodynamics and flow disorders in greater detail. This article provides a brief overview of current as well as emerging clinical applications of transesophageal echocardiography.     

Usefulness of three-dimensional transesophageal echocardiographic imaging for evaluating narrowing in the coronary arteries.

Coronary artery (CA) imaging has relied on invasive techniques for diagnosing stenotic lesions. Two-dimensional techniques are limited in obtaining optimal longitudinal views of all segments of the CA because of their spatial orientations. Three-dimensional echocardiography (3DE) may produce any desired cross-sectional views and reconstruct 3-dimensional images from a volumetric data set. Its role in CA imaging has not been fully explored. The aim of this study was to evaluate the potential of 3DE in visualizing CAs and in assessing the severity of stenosis. We performed transesophageal 3DE in 46 patients. Images were collected sequentially with the transducer rotated through 180 degrees. From the 3DE data sets of all 46 patients, cross-sectional views and 3-dimensional images of CAs were reconstructed. For segment-by-segment comparison between CA angiography and 3DE in semiquantitative analysis of coronary stenosis, 5 segments were defined for the proximal CA tree in 20 patients who underwent both procedures. The left main, anterior descending, circumflex, and right CAs were visualized from 3DE in 100%, 100%, 98%, and 72%. The available lengths of these segments from 3DE were 12+/-4 mm (range 4 to 22), 15+/-6 mm (range 6 to 36), 30+/-12 mm (range 13 to 60), and 18+/-9 mm (range 6 to 36), respectively. Comparison between 3DE and CA angiography in semiquantitative estimation of CA stenosis resulted in complete agreement in 83% of the segments (kappa value = 0.7). The sensitivity and specificity of 3DE in detecting significant stenosis (> or =50%) were 84% and 97%. In conclusion, transesophageal 3DE allows imaging of the proximal CA, detection of stenotic lesions, and estimation of the severity of stenosis.     

Intraoperative transesophageal echocardiographic imaging of double valve repair for aortic and mitral stenosis

An intraoperative echocardiographic evaluation to determine the feasibility and adequacy of the valve repair procedure is crucial for a successful repair. However, aortic valve repair in severe aortic stenosis (AS) is very limited and, consequently, its intraoperative echocardiographic evaluation has not been described well. Here, we describe an intraoperative transesophageal echocardiographic evaluation of a double-valve repair procedure for a patient with severe AS, moderate aortic insufficiency, and severe mitral stenosis.     

Effects of prolonged transesophageal echocardiographic imaging and probe manipulation on the esophagus--an echocardiographic-pathologic study

Transesophageal echocardiography is being increasingly utilized in the operating room and intensive care and ambulatory settings. However, to date no data are available concerning possible trauma of the transesophageal echocardiographic technique to the esophagus due to probe insertion, manipulation or direct ultrasound energy transmission. To test the hypothesis that transesophageal manipulations caused no traumatic or thermal injury to the esophageal mucosa, 12 animals were studied with continuous transesophageal echocardiography for a period of variable duration (mean 4.6 h +/- 51 min). The study group consisted of four monkeys (mean weight 5.7 +/- 0.6 kg and eight mongrel dogs (mean weight 29.8 +/- 1.4 kg). The eight dogs were studied during right heart bypass with full heparinization for 6.6 +/- 0.2 h, whereas the four monkeys were studied for 60 to 90 min in the absence of cardiopulmonary bypass and anticoagulation. Immediately after completion of transesophageal echocardiography in each case, the esophagus was entirely excised. Detailed macroscopic and microscopic examination of the esophagus revealed no significant mucosal or thermal injury. This preliminary animal study suggests that transesophageal echocardiography is safe for the esophageal mucosa in animals as small as 5 kg in weight, despite prolonged use and in the presence of systemic anticoagulation.     

Three-dimensional and four-dimensional transesophageal echocardiographic imaging of the heart and aorta in humans using a computed tomographic imaging probe

We evaluated the clinical applicability of a prototype tomographic transesophageal echocardiographic (TEE) system, which not only provides conventional TEE images but also three-dimensional tissue reconstruction and four-dimensional display capabilities. The probe was used in 16 patients in the echocardiographic laboratory, intensive care unit, and the operating room. The instrument is a 5-MHz, 64-element, phased array unit mounted on a sliding carriage within a casing. After appropriate probe placement within the esophagus, the probe is straightened, a balloon surrounding the probe is inflated, and data acquisition begun with ECG and respiration gating. With computer controlled transducer movement at 1-mm increments, a complete cardiac cycle is recorded at each tomographic level. These are processed using a dedicated four-dimensional software, and displayed as a dynamic three-dimensional tissue image of the heart. We were able to see the dynamic motion of the ventricles and all the valves in the four-dimensional format. In addition to four-dimensional display, we were able to cut and visualize the heart in dynamic mode in any desired plane and also in multiple planes. Patients tolerated the procedure well. We conclude that this tomographic four-dimensional approach, which does not require tedious off-line processing, can easily be performed in patients and has a strong clinical potential.     

Bedside cardiac catheterization using transesophageal echocardiographic guidance

We describe for the first time the use of transesophageal echocardiography to guide cardiac catheterization performed at the bedside in the pediatric cardiac intensive care unit. The procedure was performed on a 2.6-kg infant with ventricular and atrial septal defects after repair of coarctation of the aorta. Poor hemodynamic status prevented obtaining the required hemodynamic information from cardiac catheterization in the cardiac catheterization laboratory. Transesophageal echocardiography provided cardiac and vascular imaging, which helped guide catheter placement where the small size of the infant and the extensive thoracic postoperative bandages prevented obtaining the echocardiographic information from other windows.     

Three-dimensional transesophageal echocardiographic evaluation of cor triatriatum in adults

We present the cases of two adult patients with cor triatriatum due to left atrial membrane with atrioventricular septal defect and right atrial membrane. Two-dimensional and real-time three-dimensional transthoracic echocardiography were performed. These noninvasive modalities provided a comprehensive anatomic and hemodynamic evaluation of the anomaly.     

Coronary reserve in Takayasu's arteritis: transesophageal echocardiographic analysis

BACKGROUND: The incidence of coronary arteries lesion in Takayasu's arteritis varies from 9% to 10% and is usually discovered at autopsy. Recent studies have demonstrated the value of echocardiography in noninvasive detection of significant coronary stenosis. AIM: The aim of our study was to evaluate coronary reserve in 15 patients with Takayasu's arteritis using contrast transesophageal echocardiography (Optison). METHODS: Transesophageal echocardiogram under basal conditions and in the hyperemic phase with dipyridamole challenge, myocardial perfusion studies and coronary angiography were performed on all patients. Seventy-three percent of them had histories of systemic hypertension, and the most frequent cardiovascular symptoms were shortness of breath (80%), headache (46%), angina (40%), and dizziness (33%). RESULTS: The transthoracic echocardiogram showed left ventricular systolic dysfunction in 6% and diastolic dysfunction in 53%. Aortic regurgitation was found in 67% of the patients, and 60% had mitral and/or tricuspid regurgitation. Coronary reserve was diminished in 3 patients with significant coronary lesions and in 2 patients with coronary dilation (33%). In the 3 patients with obstructive lesions and diminished coronary reserve, reversible perfusion defects were found with thallium-201 single-photon emission computed tomography. One patient with coronary dilation had normal perfusion, while the other demonstrated reversible and irreversible perfusion defects. One patient without coronary lesions and with normal coronary reserve had an irreversible fibrotic changes and the other reversible defects due to abnormal microcirculation. CONCLUSIONS: Transesophageal echocardiography is a feasible and promising technique for assessing coronary reserve in patients with Takayasu's arteritis.     

Primary cardiac lymphoma diagnosed by percutaneous intracardiac biopsy with combined fluoroscopic and transesophageal echocardiographic imaging.

Primary cardiac tumors have very low prevalence with cardiac lymphoma, being one of the rarest forms. Several recent reports have shown transesophageal echocardiography to be an accurate technique for characterizing and localizing these neoplasms, with results comparable to CT and MRI scans. Transvenous intracardiac tumor biopsy has been employed as a minimally invasive technique to obtain tissue samples. The addition of transesophageal echocardiographic (TEE) guidance to this process has increased the accuracy of obtaining diagnostic specimens while improving patient safety. We review published cases of this relatively new technique using combined fluoroscopic and TEE guidance and present a case of primary cardiac lymphoma diagnosed by this method. The patient achieved complete tumor remission after treatment with standard chemotherapy and remains fully functional 32 months after initial diagnosis.     

Three-dimensional transesophageal echocardiographic demonstration of intraatrial baffle obstruction

We report an adult patient with transposition of the great arteries status post-Mustard procedure in whom three-dimensional transesophageal echocardiography demonstrated intraatrial baffle obstruction. The baffle could be visualized in both long-axis and "en face" short-axis views.