Search PubMed⌕ Search

Biomedical subjects

J C Tardif

Publications and source records attributed to J C Tardif.

At least 19 recordsLinked to original sources
PubMed1997

Transthoracic echocardiographic assessment of periprosthetic mitral regurgitation using intravenous injection of sonicated albumin.

Mechanical prostheses induce artifacts that decrease the accuracy of conventional transthoracic echocardiographic imaging for the detection and quantitation of periprosthetic mitral regurgitation. In 15 patients undergoing transthoracic echocardiography, injection of sonicated albumin significantly enhanced the assessment of periprosthetic mitral regurgitation with an accuracy similar to that of transesophageal echocardiography.

Adult↗
PubMed1996

Diastolic dysfunction.

Diastolic dysfunction is a syndrome characterized by impaired ventricular filling. Abnormalities in diastolic function can generally be classified as being the result of abnormal relaxation or of abnormal compliance. Diastolic dysfunction is frequently present in patients with heart failure and it is occasionally the dominant or sole cause of symptoms. It is frequently the result of the convergence of factors such as advanced age, renal dysfunction, left ventricular hypertrophy and impaired coronary perfusion. A good history and physical examination are essential for the diagnosis of diastolic dysfunction. Because it uniquely allows for the noninvasive evaluation of mitral and pulmonary venous flow and provides critical information on the cause of diastolic dysfunction and on associated abnormalities, two-dimensional and Doppler echocardiography is the most useful tool in the comprehensive assessment of diastolic function. Treatment of diastolic dysfunction is difficult and should not only focus on controlling symptoms but also include attempts at resolving the underlying cause. Relief of myocardial ischemia, control of arterial hypertension and regression of ventricular hypertrophy are important objectives of treatment.

Diastole↗
PubMed1996

Intravascular ultrasound for diagnosis of left main coronary artery stenosis.

Coronary angiography has many limitations for the assessment of coronary artery disease. Intracoronary ultrasound imaging may overcome some of these limitations by providing direct visualization of the luminal area. This report describes a case where intracoronary ultrasound imaging was useful for correct assessment of left main coronary artery disease which enabled avoidance of coronary artery bypass grafting in this patient. Intravascular ultrasound may be a good complement to coronary angiography in selected cases of left main coronary artery lesion.

Aged↗
PubMed1996

[Intravascular echography].

Intravascular ultrasound (IVUS) is an imaging method which uses one or several ultrasound transducers at the tip of catheters to visualize the morphology of arteries. IVUS was developed to provide precise information not only about arterial stenoses, but also about atherosclerotic lesions and lesions of the vessel wall. Indications for IVUS are currently being developed. One application is for the evaluation of disease of the common trunk when a doubt persists after angiography. Ambiguous lesions on angiography, particularly situated at coronary bifurcations, can also be clarified by IVUS. The precise evaluation of the real extent of atherosclerosis by IVUS makes it an ideal tool for clinical trials of regression of coronary disease. It also provides a better understanding of the apparent paradox between the minimal reduction of atheromatous plaques on angiography and the dramatic reduction of coronary events. IVUS is extremely useful to elucidate the mechanisms and complications of percutaneous interventional procedures. For example, IVUS allows a better understanding of restenosis after angioplasty (whether it is due to intimal proliferation or to vascular remodelling), elastic recall and sudden occlusion. In view of the large atheromatous mass visible on IVUS at the dilated site even after an angiographically adequate operation, insufficient angioplasty can be considered to be the third mechanism contributing to restenosis. This finding has important clinical implications, as ultrasound guidance could possibly result in better short-term and medium-term results of angioplasty. IVUS could also allow better selection of the type of operation in these patients. IVUS is also useful to facilitate adequate deployment of coronary stents, as angiographic criteria predicting ultrasonographically adequate expansion of the stent have still not been developed. By complementing angiography for the diagnosis of atheromatous disease and by monitoring percutaneous coronary operations, the role of IVUS as a clinically useful tool should continue to grow over the next few years.

Arterial Occlusive Diseases↗
PubMed1995

Effects of variations in flow on aortic valve area in aortic stenosis based on in vivo planimetry of aortic valve area by multiplane transesophageal echocardiography.

This study provides evidence that acute changes in stroke volume and cardiac output do not result in significant alterations in the anatomic AVA measured with multiplane TEE in patients with AS of moderate or severe degree. Thus, TEE could be useful in the assessment of severity of AS in both low- and high-output states.

Adult↗
PubMed1995

Biplane and multiplane transesophageal echocardiography: methodology and echo-anatomic correlations.

Transesophageal echocardiography (TEE) is one of the most significant developments in cardiology and cardiac imaging in the last decade. While monoplane TEE clearly showed the advantages of imaging from the esophagus, biplane TEE was the next important step forward. The combination of transverse and longitudinal axis images served to provide incremental information about various cardiac pathologies. Multiplane TEE is a further advancement that allows continuous visualization of cardiac anatomy by electronic or manual steering of the ultrasound beam through 180 degrees. The intermediate views obtained by beam steering provides an unlimited perspective of normal and abnormal cardiac anatomy. This ability to view cardiac structures in multiple planes aids the understanding of the spatial arrangement of normal cardiac structures and complex disorders of cardiac anatomy. Multiplane TEE technology also eases the examination by reducing the need for probe manipulation. The ability to obtain multiplane images in a sequential manner lays the foundation for three-dimensional imaging of the heart. Ongoing developments in transducer technology should further strengthen the clinical role of TEE.

Echocardiography, Transesophageal↗
PubMed1994

Determination of cardiac output using acoustic quantification in critically ill patients.

The reliability of automated acoustic quantification (AQ) in yielding real-time left ventricular (LV) area, volume, and ejection fraction has been validated. The purpose of this study was to explore the potential of AQ in providing accurate immediate determination of cardiac output in critically ill patients. A total of 48 patients were studied. One group consisted of 37 critically ill patients with indwelling Swan-Ganz catheters. In these patients, cardiac output by AQ, manual tracing of end-diastolic and end-systolic frames of 2-dimensional images, and thermodilution were measured. AQ was also compared with Doppler calculation of flow through the left and right ventricles in 11 additional patients. Adequate data for calculation of cardiac output with AQ were obtained in 78% of critically ill patients. There was an excellent correlation between AQ and off-line manual analysis for LV volumes (r = 0.94 and 0.91 for end-diastole and end-systole), ejection fraction (r = 0.85), and cardiac output (r = 0.93). AQ also correlated well with Doppler analysis (r = 0.97) and thermodilution technique (r = 0.95) in the determination of cardiac output. However, AQ slightly underestimated thermodilution measurements, with rather wide limits of agreement (-0.3 +/- 1.1 liter/min). There was a similar underestimation of cardiac output with manual analysis when compared with thermodilution. Given the absence of significant differences between AQ and manual analysis, this observation suggests that the bias is related to the echocardiographic determination of stroke volume, and not to errors from the automated border detection. It is concluded that AQ, besides providing information on LV volumes and ejection fraction, also can yield rapid measurements of cardiac output in most patients who are acutely ill.

Acoustics↗
PubMed1994

Clinical usefulness of multiplane transesophageal echocardiography: comparison to biplanar imaging.

The increased diagnostic usefulness of multiplane over biplane transesophageal echocardiography has not yet been conclusively determined. In this study the diagnostic yield of multiplanar and biplanar imaging was compared blindly by using the information content obtained from multiplane transesophageal echocardiography to that derived from biplanar type of imaging planes available in the multiplane echocardiography recordings in 80 patients with a variety of cardiac disorders. Among these patients 9 new abnormalities were identified by multiplane transesophageal echocardiography in 8 patients. Multiplane imaging yielded better delineation of 40 various lesions in 31 patients. Thus multiplane transesophageal echocardiography has a greater diagnostic yield than biplane imaging by depicting more lesions in 10% of patients and by enhanced delineation of the extent of pathologic characteristics in 39% of patients. This versatility, coupled with the ease of obtaining a vast assembly of imaging planes without undue probe manipulations, makes multiplane transesophageal echocardiography more useful than biplanar imaging.

Echocardiography↗
PubMed1994

Potential applications of intracardiac echocardiography in interventional electrophysiology.

The growth of interventional electrophysiology in recent years has placed a greater demand on imaging guidance. Currently available imaging modalities to guide interventions, while useful, have significant limitations. Intracardiac echocardiography has the potential to improve on these limitations and evolve into a modality that could provide imaging guidance, aid in the prevention or instant identification of complications, help identify and quantify ablative lesions, and contribute toward visualization of normal and abnormal conduction pathways. Ongoing developments in catheter design in the form of lower frequency, smaller size, and preshaped catheters should enhance the role of intracardiac echocardiography in interventional electrophysiology. There is the potential to combine the imaging and ablative capabilities of intracardiac ultrasonography to make for an imaging and therapeutic tool.

Cardiac Catheterization↗
PubMed1994

Delineation of extended lengths of coronary arteries by multiplane transesophageal echocardiography.

OBJECTIVES: The purpose of this study was to evaluate the utility of multiplane transesophageal echocardiography in assessing the coronary artery tree. BACKGROUND: Evaluation of coronary disease with single-plane and biplane transesophageal echocardiography is limited to the very proximal vessels. The numerous views provided by multiplane imaging may enhance visualization of coronary arteries and detection of their abnormalities. METHODS: Intraoperative multiplane transesophageal echocardiography was performed in 45 consecutive adults who had recently undergone angiography. Recordings were reviewed in blinded manner. RESULTS: We describe the coronary segments visualized with the different imaging planes and define new views. The left main coronary artery with its bifurcation was visualized in all 45 patients. Sensitivity and specificity for detection of coronary narrowings were 100% when results were compared with angiographic data. Visualization of proximal, mid and distal segments of the left anterior descending coronary artery was possible in 69%, 31% and 16% of patients, respectively. Among patients in whom the proximal segment was visualized, sensitivity and specificity for detection of significant narrowings were 80% and 100%. Proximal, mid and distal portions of the left circumflex coronary artery were visualized in 80%, 51% and 20% of patients. Among patients in whom the proximal portion was well seen, sensitivity and specificity were 89% and 100%. The proximal, mid and distal portions of the right coronary artery were visualized in 84%, 16% and 11% of patients. Among patients in whom the proximal segment was visualized, sensitivity and specificity were 82% and 100%. Color Doppler examination was less useful because it detected only 52% of all patients with proximal stenosis. CONCLUSIONS: Multiplane transesophageal echocardiography allows enhanced visualization of extended lengths of coronary arteries and the reliable identification of coronary artery abnormalities.

Adult↗
PubMed1994

Intravascular ultrasound imaging in peripheral arterial and coronary artery disease.

Intravascular ultrasound is an emerging imaging modality that employs miniaturized transducers at the tips of catheters to provide detailed information about the morphology of small and large arteries. While there is ongoing development in technology, currently available intravascular ultrasound instrumentation already augments angiography in the assessment of structural and dynamic abnormalities of the peripheral and coronary arterial systems. Recent studies have consistently demonstrated significant underestimation of atherosclerotic disease by angiography. Demonstration by intravascular ultrasound of disease in the angiographically normal "reference" segment and of remodeling of the diseased segment may explain this angiographic underestimation. Intravascular ultrasound also has many applications during various catheter-based therapeutic procedures. In addition to contributing to our understanding of the mechanisms of interventions and restenosis, intravascular ultrasound may lead to better guidance and ultimately better outcome during various procedures such as balloon angioplasty, atherectomy, and stent placement.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Aneurysm of the membranous ventricular septum and accessory valvular tissue causing obstruction of the pulmonary outflow tract in corrected transposition.

Aneurysm of the membranous portion of the ventricular septum and accessory valvular tissue are two infrequent congenital lesions. This case illustrates a rare association of aneurysm of the membranous septum and accessory valvular tissue originating from the mitral valve, causing right-sided ventricular outflow tract obstruction in a patient with corrected transposition. Multiplane transesophageal echocardiography allowed for determination of the dual nature of the obstruction.

Adult↗
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

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

Angiosarcomas of the interatrial septum mimicking atrial myxomas.

Angiosarcoma of the heart is a rare tumor. This tumor is most frequently located in the right atrium and pericardium. Localization of a tumor in the interatrial septum usually suggests atrial myxoma. We report two cases of angiosarcoma originating from the interatrial septum, one extending into the right atrium and the other into the left atrium, mimicking atrial myxomas. Transesophageal echocardiography allowed the diagnosis and comprehensive assessment of compromised structures.

Aged↗