Subcostal real-time three-dimensional echocardiography of interatrial communications: reconstruction of an oval fossa defect, a superior sinus venosus defect with partially anomalous pulmonary venous drainage, an infero-posterior oval fossa defect, and a coronary sinus defect

Real-time three-dimensional echocardiography can surpass simple cross-sectional echocardiography in providing precise details of cardiac lesions. For the purpose of optimising treatment, we describe our findings with real-time three-dimensional echocardiography when interrogating different types of communications permitting interatrial shunting. A three-dimensional reconstruction of defects within the oval fossa enabled reliable identification of location, size, and integrity of surrounding rims. In the superior sinus venosus defect associated with partially anomalous pulmonary venous drainage, three-dimensional reconstruction helped to provide a better understanding of the relationship between the interatrial communication, the orifice of the superior caval vein, and the connections of the right upper pulmonary vein. In the defect opening infero-posteriorly within the oval fossa, three-dimensional reconstruction helped to avoid the risk of potentially inappropriate closure of the defect by suturing the hyperplastic Eustachian valve to the atrial wall, which could have diverted the inferior caval venous return into the left atrium, or obstructed the caval venous orifice. In the coronary sinus defect, three-dimensional echocardiography provided a 'face to face' view of the entire coronary sinus roof, showing a circular defect communicating with the cavity of the left atrium. Acquisition of the full-volume data sets took less than 2 minutes for the patients having defects within the oval fossa, and no more than 3 minutes for the patients with the sinus venosus and coronary sinus defects. Post-processing for the defects in the oval fossa took from 5 to 8 minutes, and from 12 to 16 minutes for the more complicated defects. CONCLUSION: Cross-sectional two-dimensional echocardiography can establish correct diagnosis in all types of atrial communications; however, real-time three-dimensional reconstruction provides additional value to the surgeon and interventionist for better understanding of spatial intracardiac morphology.     

Prolapsing left atrial myxoma: preoperative diagnosis using a multimodal imaging approach with magnetic resonance imaging and real-time three-dimensional echocardiography

Real-time three-dimensional echocardiography (RT3DE) is a newpromising technique for the evaluation of intracardiac masses.We present the diagnostic work-up using a multimodal-imagingapproach in a 74-year-old patient with a prolapsing tumour inthe left atrium suggestive of a myxoma, causing severe congestiveheart failure attributable to dynamic left ventricular inflowobstruction, and mimicking severe mitral valve stenosis. Real-timethree-dimensional echocardiography allowed to accurately imagethe entire volume of the myxoma, and to analyse the dynamicleft ventricular inflow obstruction. The size of the lobulatedmass as assessed by RT3DE was 65 x 25 x 22 mm. The mass was surgically removed, histology was diagnostic formyxoma, and the patient had an uneventful recovery. Real-time three-dimensional echocardiography images the entirevolume of a mass allowing for accurate measurements in multipleplanes, and allowing for real-time evaluation of obstructiveeffects on ventricular in- or outflow. This case shows how RT3DEand other non-invasive imaging modalities may be used as complementarytechniques for evaluation of intracardiac masses.     

Utility of three-dimensional echocardiography during balloon mitral valvuloplasty

Objectives. We investigated the role of three-dimensional echocardiography in assessing mitral valve anatomy in greater detail in patients immediately before and after balloon mitral valvuloplasty (BMV).Background. Three-dimensional echocardiography is a recently developed, evolving imaging technique that allows visualization of intracardiac structures from any perspective.Methods. We studied 19 patients undergoing BMV using transesophageal echocardiography (TEE) (Chicago, Illinois) to image the mitral valve. The TEE was interfaced to a TomTec three-dimensional workstation that allows electrocardiographic and respiratory cycle gated image acquisition. The acquired images are digitized, and after postprocessing a three-dimensional image is reconstructed. The mitral valve was viewed “en-face” as if looking up from the left ventricle.Results. The mean mitral valve area (by pressure half-time from the Doppler of the two-dimensional echocardiogram) increased after BMV from 0.86 ± 0.06 cm²to 2.07 ± 0.10 cm², p < 0.0001. This was similar to the mitral valve areas obtained by planimetry from the three-dimensional images. The three-dimensional reconstructions showed a complete commissural split in 10 patients and partial splitting in 9 patients. In three of the eight patients who had an increase in the amount of mitral regurgitation secondary to BMV, the three-dimensional reconstructions were able to detect tears within the valve leaflet. One leaflet tear actually extended up to the mitral valve annulus and was associated with the only case of severe mitral regurgitation.Conclusions. The three-dimensional echocardiographic reconstruction enabled visualization of the mitral valve so that commissural splitting and leaflet tears not seen on the two-dimensional echocardiogram became visible.     

A billiard ball in the left atrium

An 84-year-old woman with a history of severe systolic heart failure, a mechanical mitral valve, and atrial fibrillation presented to the hospital with syncope and is found to have a free-floating intracardiac mass on transthoracic echocardiogram that was absent 5 months earlier. Real time three-dimensional (3D) transesophageal echocardiography (TEE) images reveal a billiard-ball-looking mass thought to be a large left atrial thrombus causing syncope by transiently obstructing the mitral valve orifice. Real time 3D TEE offers several potential advantages for the evaluation of intracardiac masses.     

Neue Entwicklungen in der bildgebenden Diagnostik der Mitralinsuffizienz

Conventional Doppler echocardiographic methods still are limited when being used for evaluation of morphology and function of a regurgitant mitral valve. Methods based on two-dimensional image planes may be insufficient to demonstrate exact spatial localization of pathologic structures due to the need for mental reconstruction of the three-dimensional valve anatomy by the examiner. The determination of severity of mitral regurgitation is based either on the estimation of regurgitation jet size or on geometric assumptions on its shape which often are not correct and reduce the accuracy of the method.New echocardiographic techniques such as 3-D echocardiography provide a comprehensive visualization and assessment of valvular pathomorphology which especially in complex situations will increase sensitivity and diagnostic accuracy when compared to conventional methods. The combination of 3-D echo with three-dimensional Doppler data will allow an even more reliable and precise determination of lesion severity. Other imaging modalities such as magnetic resonance imaging will be a promising alternative due to their three-dimensional data acquisition and the enormous potential for the measurement of intracardiac flow.     

Utility of in vivo, intracardiac two-dimensional echocardiography in the assessment of myocardial risk area and myocardial dyssynergy during coronary occlusion and reperfusion

We have previously reported the potential use of intracardiac echocardiography (ICE) in a variety of clinical settings, including detection of pericardial effusion, intracardiac masses, congenital cardiac defects, and during simulated balloon valvuloplasty. The utility of intracardiac ultrasound imaging of the left ventricle (LV) in patients with coronary disease needs to be further explored. We performed this study with the purpose of evaluating risk area and regional wall-motion abnormalities produced by ischemia using ICE. Ten episodes of ischemia were produced by transiently occluding the left anterior descending coronary artery in five dogs. ICE was performed with a modified 5-MHz transesophageal echocardiographic probe placed in the right atrium. Continuous short-axis images of the LV were obtained before, during, and after coronary occlusion. Risk area was defined using myocardial contrast echocardiography. In all cases, ICE provided high resolution images of the LV. Risk area and regional wall-motion abnormalities were readily detected. There was good correlation between the risk area (x) and extent of dyssynergy (y), defined by the equation y = 0.76x + 6.38 (r = 0.80, P less than 0.01). We conclude that ICE provides potentially useful information concerning regional LV dysfunction, and, when combined with myocardial contrast echocardiography, area at risk. This technique may be useful during interventional procedures once a catheter-based ultrasound transducer with adequate depth of field to provide images of the entire LV can be developed.     

Real-time, intracardiac, two-dimensional echocardiography: enhanced depth of field with a low-frequency (12.5 mhz) ultrasound catheter

Advances in catheter-based ultrasound imaging technology allow for a unique opportunity to develop two-dimensional intracardiac echocardiography, an imaging method that could have significant clinical applications. In this study, we evaluated the potential of a new, percutaneous, 9-Fr prototype intracardiac echocardiographic catheter with a 12.5-MHz rotating crystal in 13 dogs. In all dogs, we were able to easily advance the intracardiac echocardiographic catheter into the right and left hearts percutaneously and obtain dynamic images of cardiac structures in various imaging planes. With the intracardiac echocardiographic catheter in the right atrium, the whole chamber could be visualized. Minor manipulation allowed visualization of the right atrium, right ventricle, and tricuspid valve in a two-chamber view; further maneuvering yielded four-chamber views. With advancement of the catheter into the right ventricle and pulmonary artery, the right ventricular cavity, right ventricular outflow tract, and pulmonary artery could be imaged. The intracardiac echocardiographic catheter in the aortic root allowed visualization of the pulmonary artery and its bifurcation, superior portions of the atria, interatrial septum, aortic valve, and the proximal left coronary artery. With the intracardiac echocardiographic catheter in the left ventricle, short-axis images of the whole left ventricle were obtained. Manipulating the catheter tip within the left ventricle, we could visualize the left ventricle, left atrium (LA), and the mitral valve in the long axis. We were also able to visualize and identify experimentally-induced ischemic regional left ventricular dyskinesis (four of of five dogs), aortic valvular tear (five out of five dogs), and pericardial effusion with right atrial collapse (two out of two dogs). Intracardiac echocardiography was not associated with any complications. We conclude that percutaneous, low-frequency intracardiac echocardiography with a 12.5-MHz, 9-Fr catheter yields cardiac images in many imaging planes with a good depth of field, allows identification of valvular, myocardial, and pericardial abnormalities, and has excellent clinical potential in the assessment of many cardiovascular disorders.     

Real-time, three-dimensional localization of a Brockenbrough needle during transseptal catheterization using a nonfluoroscopic mapping system

We describe a new technique that allows real-time, three-dimensional (3-D) localization of the Brockenbrough needle tip during transseptal catheterization using the EnSite NavX system. Transseptal catheterization has been traditionally performed using fluoroscopy, and recently, with the use of intracardiac echocardiography. However, even intracardiac echocardiography has the limitation of providing only 2-D views limited to the ultrasound plane. By displaying the transseptal needle on the EnSite NavX system, we achieved real-time 3-D localization of the needle tip within the right atrial geometry and found accurate visual correlation between fluoroscopy, intracardiac echocardiography and nonfluoroscopic 3-D cardiac mapping. This study suggests that the EnSite NavX system is able to provide 3-D localization of the transseptal needle during transseptal catheterization, and may be a useful imaging modality in this procedure.     

Real-time three-dimensional stress echocardiography: a Review of current applications

Cardiovascular stress testing plays a crucial role in the initial detection of coronary artery disease. In exercise stress echocardiography, the rapid acquisition of echocardiographic images is critical for accuracy. Real-time three-dimensional echocardiography permits the rapid acquisition of a volumetric data set that includes the entire left ventricle and allows the review of multiple, standard two-dimensional images from a single volumetric data set. Volumetric data can be obtained using both apical and parasternal windows. Often, satisfactory images are obtained in the majority of both prestress and poststress imaging using only an apical volume set. The following is a review of the current applications of real-time three-dimensional echocardiography in stress testing.     

Accurate volume determination in the isolated ejecting canine left ventricle by two-dimensional echocardiography.

Two-dimensional echocardiography can provide serial cross-sectional images of the left ventricular cavity. We examined whether such serial images from steady-state ejecting hearts would allow three-dimensional reconstruction and accurate volume estimation without major geometric assumptions. Cross-circulated, paced dog hearts were suspended in a blood-filled tank. Serial cross-sectional images were taken at 3-mm intervals along the vertical axis. Left ventricular cavity and muscle areas of each image were planimetered with a light-pen system and summated for volume: total volume = sigma (areas x 3 mm). Direct left ventricular volume was measured through the cardiac cycle with a volumetric chamber connected to a balloon in the ejecting left ventricle. In six hearts, 67 separate direct volume measurements (range 9.5--54.7 ml) from various points in the cardiac cycle were compared with the simultaneous echo volume measurements. By least squares linear regression, echo volume = 1.01 (direct volume) - 0.44 ml; r = 0.972, SEE = 2.93 ml. Provided accurate cross-sectional localization is available, these studies suggest that extremely accurate steady-state left ventricular volume can be determined noninvasively in the ejecting heart from multiple cross-sectional images.     

Dynamic Three-Dimensional Reconstruction of Abnormal Intracardiac Blood Flow

Dynamic three-dimensional (3-D) echocardiography has so far focused on reconstruction of cardiac structures. In this preliminary study, abnormal intracardiac blood flow has been reconstructed in 3-D from multiplane transesophageal and transthoracic two-dimensional (2-D) echocardiograms using modified omniplane probes with 3.7- or 5.0-MHz transducers. The study group included patients with native (40) and prosthetic (11) mitral regurgitant jets, aortic regurgitant jets (8), and shunt flow in atrial septal defect (20), ventricular septal defect (19), tetralogy of Fallot (14), and ruptured sinus of Valsalva aneurysm (6). For dynamic 3-D intracardiac flow imaging the gain of 2-D images of cardiac structures was lowered slightly and color Doppler flow signals were transformed into gray scale flow signals, which were then collected in the TomTec 3-D Echo Scan System. Dynamic 3-D cardiac flow images were displayed with volume rendering. The results indicated that dynamic 3-D cardiac flow imaging facilitates display of the stereo shape, spatial orientation, profiles and volume of regurgitant jets, and the intracardiac shunting blood flow. It allows differentiation of prosthetic transvalvular from paravalvular regurgitant jets. Limitations include nonvelocity and nonECG synchronized display.     

Intracardiac echocardiography. Experimental observations on intracavitary imaging of cardiac structures with 20-MHz ultrasound catheters

Recently catheter-based ultrasound devices have become available for obtaining high-resolution images of blood vessels. In this study we evaluated the feasibility of imaging cardiac structures using 20-MHz ultrasound catheters. In 25 dogs, the ultrasound catheter was advanced into the right and left heart chambers percutaneously. The intravascular devices yielded images of the right atrial wall, right and left ventricular myocardia, tricuspid, pulmonic, and aortic valves, and the great vessels. Although the small depth of field inherent to the frequency range of 20 MHz limited the visualization to only portions of the cardiac chambers, the images obtained were of high resolution and allowed easy identification of the various cardiac structures. Intracardiac echocardiography was easy to perform and did not result in damage to the cardiac structures. We conclude that intracardiac echocardiography using ultrasound catheters provides a new approach to cardiac imaging and that the development of lower frequency catheters could aid in extending the potential utility of intracardiac echocardiography.     

First experience with "live" three-dimensional echocardiography in Russia

Revival of interest to three-dimensional echocardiography during recent years was invoked by introduction of essentially novel ultrasound technology of "live" three-dimensional imaging. We introduce here the first experience of the use of three-dimensional echocardiography in Russia comprising examination of 74 patients with various pathology of the heart. Positions and sections are described allowing best visualization of pathology of cardiac valves and other intracardiac structures. Our experience shows that at present three-dimensional echocardiography should be considered to be an important supplement to standard echocardiography. However in some cases it can be the only non-invasive technique able to provide complete information on the size of ventricular and atrial septal defects, valvular and other cardiac pathology.     

Dynamic three-dimensional reconstruction of the left ventricle from two-dimensional echocardiograms

Using an open chest canine model, a method was developed for three-dimensional reconstruction of the contracting left ventricle from two-dimensional echocardiograms, which is applicable to intraoperative studies in humans. A mechanically held 5 MHz transducer was used to record parallel high resolution cross-sectional images with precise spatial registration. Myocardial borders were tracked manually and entered into a computer system. Regional filling and interpolation routines were applied to reconstruct the endocardial and epicardial surfaces of the ventricle. The myocardium can be displayed as a translucent, shaded three-dimensional solid surrounding the ventricular cavity. One or both surfaces can be rotated about any axis, sectioned through any plane and viewed in motion through systole and diastole. Studies before and after left anterior descending coronary artery occlusion showed the three-dimensional extent of abnormal left ventricular cavity and myocardial deformation. Quantitative examination of regions of interest permits the analysis of global and regional volumetric and myocardial thickness changes throughout the cardiac cycle. Thus, open chest three-dimensional echocardiography provides a powerful tool for the quantitative physiologic investigation of the left ventricle.     

Recent advances in cardiac mapping techniques

Recently several new mapping modalities have been introduced into clinical electrophysiologic laboratories, including basket catheter mapping, electromagnetic mapping, and noncontact mapping. In addition, intracardiac echocardiography is being used increasingly to visualize important intracardiac structures for catheter ablation. Basket catheter mapping and noncontact mapping are simultaneous mapping devices, whereas electromagnetic mapping is a sequential mapping tool. The new basket-shaped catheters provide up to 64 electrodes mounted on a variable number of splines that encircle the cardiac contour. Animation programs help in identifying the earliest activation and analyzing the activation sequence. Electromagnetic mapping uses low density magnetic fields to navigate the catheter position and to allow nonfluoroscopic mapping and ablation. Sequential recording of intracardiac potentials produces a real-time, color-coded, three-dimensional activation map. Noncontact mapping does not require direct contact with the endocardium and permits the reconstruction of more than 3000 simultaneous computed electrograms via mathematical algorithms. Three-dimensional isopotential maps are generated to visualize the impulse propagation and guide catheter ablation.     

Intracardiac ultrasound determination of left ventricular volumes: In vitro and in vivo validation

Objectives. This study was designed to assess the feasibility of calculating left ventricular volumes using intracardiac ultrasound.Background. Previous studies have validated transthoracic echocardiographic determinations of left ventricular volumes and have indicated the superiority of Simpson rule reconstruction algorithms. The feasibility of imaging the left ventricle with intracardiac ultrasound has also been demonstrated.Methods. The determination of left ventricular volumes with Simpson rule reconstruction of intracardiac ultrasound images was evaluated in two phases. In vitro validation was performed in 29 animal hearts preserved in either a nondistended or distended state. Latex cast volumes were the reference standard. In vivo studies used 14 pigs, and compared intracardiac ultrasound volumes and ejection fraction with single-plane contrast angiographic values. A 12.5-MHz device was used to record short-axis images at 0.5-cm intervals. These were used to reconstruct the ventricle as a stack of cylindric elements using all imaged levels as well as sections recorded every 1 and 2 cm and at a single midventricular level.Results. In the in vitro hearts, when all recorded sections were used, there was excellent agreement between intracardiac ultrasound and latex cast volumes (intracardiac ultrasound volume = 0.89 latex cast volume + 2.22, r = 0.95; intracardiac ultrasound volume = 0.97 latex cast volume + 0.91, r = 0.99) for nondistended and distended hearts, respectively. In vivo, there was again close correspondence between ultrasound and angiographic volumes (intracardiac ultrasound volume = 1.04 angiographic volume −3.6, r = 0.91). The relation between intracardiac ultrasound and angiographic ejection fraction was fair (intracardiac ultrasound ejection fraction = 1.00 angiographic ejection fraction + 6.85, r = 0.69). Excellent correlations for the volumes were maintained as the number of cross sections was reduced to those recorded every 1 and 2 cm (r = 0.87 to 0.99). With a single midventricular site more variable but generally good correlations were obtained (r = 0.77 to 0.99).Conclusions. The application of Simpson rule reconstruction to short-axis images of the left ventricle obtained with intracardiac ultrasound provides accurate determination of left ventricular volumes in animal hearts. This technique may prove useful in the analysis of left ventricular structure and function.     

Live/real time three-dimensional transthoracic echocardiographic findings in primary left atrial leiomyosarcoma

We describe an adult patient with a primary left atrial leiomyosarcoma in whom live/real time three-dimensional transthoracic echocardiography showed echolucent areas within the mass consistent with necrosis or hemorrhage surrounded by dense band-like echo densities indicative of fibrosis or collagen giving a "doughnut" like appearance. These findings were consistent with histopathology, which showed areas of necrosis and dilated vascular channels within the fibrotic tumor. Our case further illustrates the usefulness of three-dimensional transthoracic echocardiography in characterizing the morphologic features of an intracardiac mass.     

Semi-automated 3-dimensional intracardiac echocardiography: Development and initial clinical experience of a new system to guide ablation procedures

BACKGROUND: Pre-interventional three-dimensional (3D) reconstruction of the heart by CT or MRI provides important information on cardiac anatomy for electrophysiological interventions. However, updates of 3D-imaging modalities with high soft-tissue contrast are not available during ablation procedures. OBJECTIVE: We describe the development and first clinical testing of a close to real-time visualization of cardiac anatomy by intracardiac echocardiography (ICE). METHODS: An electronic phased-array 5-10 MHz ICE-catheter (AcuNav/Siemens/64 elements) was inserted via a straightened femoral vein sheath (12F) and placed in the right atrium in 5 pigs. A custom-made prototype stepper motor allowed automatic rotation around the longitudinal axis from 90 degrees to 360 degrees in 2-5 degrees steps. For every plane 2D images of a complete cardiac cycle were acquired, triggered by respiration and ECG. The ultrasound images were digitized and 3D-reconstruction was performed by a prototype software. After experimental validation the system was tested in 6 patients during electrophysiological studies. RESULTS: From a single location in the right atrium, 3D-acquisition and reconstruction of both atria and ventricles with good image quality were achieved within 3-5 minutes. Doppler-mode facilitated identification of the great vessels including the pulmonary veins and their entry into the heart. 3D-visualization of ablation catheters was also possible in all patients and pigs. CONCLUSION: Semi-automated 3D intracardiac echocardiography from a single site inside the right atrium provides the electrophysiologist with a detailed image of both atria and ventricles with repeated updates of the cardiac anatomy.     

Percutaneous left atrial appendage closure in awake non intubated patient: Multimodality intraprocedural imaging

We present a case of percutaneous left atrial appendage closure in awake non intubated patient, in which Intraprocedural ultrasound images were obtained with a micro transesophageal echocardiographic probe (MTEE) and intracardiac echocardiography (ICE) together with angiography.