Biomedical subjects

N G Pandian

Publications and source records attributed to N G Pandian.

155 records · Page 9Linked to original sources

PubMedDate not supplied

Detection of partial anomalous right pulmonary venous return with an intact atrial septum by transesophageal echocardiography.

Partial anomalous pulmonary venous drainage with intact atrial septum is a rare congenital anomaly. We report a case of a 63-year-old woman who recently had dyspnea on minimal exertion and was found to have pulmonary hypertension, right atrial enlargement, and right ventricular enlargement by two-dimensional transthoracic echocardiography. Transesophageal echocardiography demonstrated anomalous venous drainage of the right lung into the superior vena cava with an intact interatrial septum. This diagnosis was confirmed by angiography and the patient underwent successful repair. This case illustrates the importance of locating all four pulmonary veins in patients with pulmonary hypertension or suspected intracardiac shunt in addition to scanning the atrial septum.

Echocardiography, Transesophageal↗

PubMedDate not supplied

Volumetric multiplexed transmission holography of the heart with echocardiographic data.

Three-dimensional imaging enhances delineation of cardiac anatomy and function. Currently, three-dimensional echocardiography involves complex rendering techniques to imply depth in a given image. Also, display of the final images on a video monitor neutralizes the volume information of the object. A hologram is a true, three-dimensional replica of the original object and does not entail complex data processing. Holography has not been used previously in cardiovascular imaging. In this experiment, 11 excised mammalian whole hearts and five isolated left ventricles were imaged in a water bath. Parallel, tomographic, echocardiographic images comprised the data source from which holograms were obtained by the technique of multiplexed holography. Holograms were mounted on a holographic film and viewed in a special viewing box. High-quality holograms were obtained from every data set. Excellent gray-scale discrimination allowed crisp visualization of cardiac structures and simulated diseases. Electronic sectioning and various projections optimized viewing of the three-dimensional anatomy in surgical orientations. Thus holograms can be produced from tomographic cardiac ultrasound data and could open a new avenue in three-dimensional echocardiography.

Animals↗

PubMedDate not supplied

Intracardiac echocardiography with a steerable low-frequency linear-array probe for left-sided heart imaging from the right side: experimental studies.

Despite a need for intracardiac echocardiographic guidance during interventional procedures, an optimal catheter device is not available. The depth of field of catheters bearing 10 to 20 MHz transducers does not allow easy or complete visualization of the left side of the heart from the right side of the heart. Lower frequency transducers would be required to increase the depth of view of such rotational devices. These low-frequency transducers would require an expanded aperture and thus a larger catheter size. Other transducer modalities that could exploit the length of the imaging device rather than the circumference could potentially solve the problem of aperture size. To examine whether a linear-array transducer could provide adequate images of the left side of the heart from the venous side, we employed a prototype 7 MHz linear-array probe with a steerable tip inside eight animal hearts. Atrial and ventricular septal defects were created experimentally. The device was introduced into the right side of the heart through the inferior and superior vena cavae. Intracardiac imaging with this probe allowed visualization of the left side of the heart and major arteries from the right side with excellent image quality. By advancing the probe in various locations in the right side of the heart and using the steerability of this device, we were able to identify useful imaging planes for different cardiac structures. Atrial and ventricular septal defects were also detected easily and delineated clearly. The concept of a low-frequency (< 8 mHz) linear-array probe for intracardiac echocardiography may represent another step toward "whole-heart imaging" from the venous side.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Visualization of left ventricular pseudoaneurysm with panoramic transesophageal echocardiography.

The diagnosis and precise delineation of a pseudoaneurysm of the left ventricle have important implications regarding surgical planning and operative repair. A 68-year-old man was admitted to the hospital with the incidental finding of a large pseudoaneurysm of the left ventricle 6 months after a St. Jude mitral valve replacement performed for partial papillary muscle rupture after an acute myocardial infarction. Panoramic transesophageal echocardiography provided a full depiction of the left ventricle and the adjoining pseudoaneurysm, enhancing the preoperative evaluation of the extent of the defect. A successful repair was undertaken with a pericardial patch.

Aged↗

PubMedDate not supplied

Delineation of pulmonary artery sarcoma with multiplane and panoramic transesophageal echocardiography.

A 38-year-old woman came for treatment with massive hemoptysis. A hilar density was observed on a chest radiograph. Transthoracic echocardiography demonstrated an intravascular pulmonary arterial mass that was studied in further detail with multiplane and panoramic transesophageal echocardiography. Surgical resection proved the mass to be a sarcoma arising from the main pulmonary artery. This case report demonstrates the utility of multiplane and panoramic transesophageal echocardiography in the study of intravascular tumors of the thorax.

Adult↗

PubMedDate not supplied

Right ventricular outflow tract and pulmonary artery obstruction by postoperative mediastinal hematoma: delineation by multiplane transesophageal echocardiography.

A 53-year-old man with osteogenesis imperfecta underwent valve replacement and coronary artery bypass surgery. Unexplained symptoms of dyspnea and fatigue in the late postoperative period prompted further evaluation. Transthoracic echocardiography demonstrated obstruction of the right ventricular outflow tract and pulmonary artery by a mass, with a maximum gradient of 50 mm Hg. Multiplane transesophageal echocardiography revealed that the mediastinal hematoma was more extensive than was suggested by the transthoracic echocardiogram. This finding prompted the decision to resort to a more extensive surgical procedure. Surgical drainage continued until no residual hematoma could be visualized by multiplane transesophageal echocardiography. This case report demonstrates the value of multiplane transesophageal echocardiography in the assessment of mediastinal masses.

Aortic Valve↗

PubMedDate not supplied

Intracardiac two-dimensional echocardiography in patients with pericardial effusion and cardiac tamponade.

The utility of intracardiac two-dimensional echocardiography in the identification of pericardial effusion was assessed in five patients with pericardial effusion and cardiac tamponade. A 20 MHz, mechanically rotating ultrasound catheter was used for intracardiac imaging. In all five patients, intracardiac echocardiography yielded high resolution of images of the right atrial cavity, the right atrial wall, and the pericardial effusion. In two patients, right atrial collapse could be identified during real-time imaging. Although the entire right atrial cavity and the pericardial effusion could not be displayed in a single imaging field because of the limited depth of field associated with the 20 MHz catheter, manipulation of the catheter allowed visualization of the pericardial effusion and the parietal pericardium in each patient. The effusion was seen to surround the superior vena cava, as well, in all patients. After pericardiocentesis, the reduction in the size of the effusion and increase in the right atrial cavity size could be recognized by intracardiac echocardiography. The introduction and manipulation of the ultrasound catheter was easily performed without any complications. This experience presents one clinical application for intracardiac echocardiography and indicates its potential value in the invasive cardiac laboratory.

Cardiac Catheterization↗

PubMedDate not supplied

Intracardiac echocardiographic imaging of cardiac abnormalities, ischemic myocardial dysfunction, and myocardial perfusion: studies with a 10 MHz ultrasound catheter.

Intracardiac echocardiography (ICE), an echocardiographic examination from within the heart itself, has been proposed as a new modality for cardiac imaging. A major shortcoming has been the limited depth of field provided by previously available devices. We used 10 MHz catheters for ICE to determine if this lower frequency would allow for greater display of cardiac anatomy. We performed ICE in seven animals; myocardial ischemia was induced in three. With the imaging catheter in the right atrium, all four cardiac chambers and valves could be imaged. Advancing the transducer into the right ventricle allowed for short-axis images of the left ventricle. Coronary perfusion territories and segmental wall motion abnormalities could be observed. We then performed ICE in six patients by advancing the catheter into the right side of the heart percutaneously. Structures of the right side of the heart, the mitral valve, aortic valve, left atrium, and portions of the left ventricle, were visualized. Congenital and acquired abnormalities could be identified. There were no complications. We conclude that ICE with 10F, 10 MHz ultrasound catheters allows for expanded imaging capabilities because of the increased depth of field. With this imaging modality, congenital and acquired abnormalities as well as myocardial ischemia can be detected.

Adult↗

PubMedDate not supplied

Intravascular ultrasound estimation of arterial stenosis.

The evaluation of the degree of reduction in the cross-sectional area of an artery has important pathophysiologic and therapeutic implications. Currently, no technique can easily provide this information. In this in vitro study we evaluated the potential of a new imaging technique, intravascular high frequency ultrasound angioscopy, in the estimation of percentage of cross-sectional area stenosis of an artery. To do this, we compared intravascular high frequency ultrasound to previously-validated external high frequency ultrasound and to anatomic estimation of arterial stenosis. Using a prototype intraluminal imaging catheter with a 20 MHz ultrasound transducer at its tip, we imaged 20 arterial segments of various size (15 to 90 mm2 lumen area by anatomy) in the control state and after experimental stenosis. These arterial segments were also imaged by external high frequency ultrasound. Lumen areas were measured from calibrated ultrasound images in the control state and after stenosis, and percentage of cross-sectional area stenosis was calculated. These data were compared to the percentage of area stenosis derived from calibrated anatomic photographs of the arteries taken in the control state and after stenosis. Both intravascular ultrasound angioscopy and external high frequency ultrasound yielded high-resolution, two-dimensional, circumferential images of the arteries. Alterations in vessel area and shape were apparent after creation of stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗

PubMedDate not supplied

On-line echocardiographic assessment of hemodynamic indexes by an adaptive Doppler analysis algorithm and signal/noise ratio calculation.

Assessment of cardiac diseases commonly involves the use of spectral Doppler echocardiography. Its use, however, often requires manual digitization of various transvalvular flow profiles. A new approach has been developed for on-line analysis of Doppler data, which involves thresholding based on the signal/noise ratio, calculating instantaneous values, and plotting on the spectral display in real time. We examined the reliability of this new method in 32 patients with 59 various flow jets by comparing it with the data derived by manual analysis. Correlations between the algorithm analysis and manual analysis for peak velocity, peak gradient, velocity-time integral, and acceleration time were excellent. These indexes were obtained with the algorithm in a shorter time and with better reproducibility than with manual analysis. Thus this new adaptive Doppler analysis algorithm yields reliable on-line quantification of valuable hemodynamic variables and represents an advance in quantitative echocardiography.

Algorithms↗

PubMedDate not supplied

Intraoperative transesophageal echocardiography: correlation of echocardiographic findings and surgical pathology.

Before the introduction of transesophageal echocardiography (TEE) in the operating room, intraoperative echocardiography relied on epicardial imaging. The disadvantages of this approach included interference with the surgical procedure, limited windows, and potential distortion of cardiac structures. Consequently, multiplane TEE has now emerged as the intraoperative imaging method of choice. It provides high-resolution images of cardiac structures and excellent portraits of flow abnormalities. Intraoperative TEE does not interfere with the surgical field and procedure. TEE provides better imaging of the valves, atria, aorta, pulmonic vasculature, and pericardium, which are sometimes difficult to visualize by transthoracic echocardiography. TEE is especially beneficial in surgeries for valve replacement, valve repair, cardiac mass, aortic disease, congenital heart disease, and pericardial disease. Presurgical TEE provides information for surgical planning. TEE is helpful for the assessment of the immediate result of surgery and detection of complications that may need a prompt response. Thus, intraoperative TEE has a vital impact on management of cardiac surgery.

Echocardiography, Transesophageal↗