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N G Pandian

Publications and source records attributed to N G Pandian.

At least 109 records · Page 6Linked to original sources
PubMed1991

Left ventricular diastolic collapse. An echocardiographic sign of regional cardiac tamponade.

BACKGROUND: Cardiac tamponade after cardiac surgical procedures is often associated with hemodynamically significant localized pericardial effusions. The localized collection of pericardial effusion in the postoperative period and the atypical presentation of cardiac tamponade limit the use of conventional clinical and echocardiographic signs usually seen with a circumferential pericardial effusion. Observation of left ventricular diastolic collapse in the echocardiogram of a patient with postoperative regional cardiac tamponade prompted us to explore the frequency of this sign in regional cardiac tamponade. METHODS AND RESULTS: We retrospectively analyzed the echocardiograms of 18 patients with postoperative cardiac tamponade for the following echocardiographic findings: right atrial collapse, right ventricular diastolic collapse, left atrial collapse, and left ventricular diastolic collapse. Three of the 18 patients had circumferential pericardial effusion, and 15 had loculated pericardial effusion; in 10, the effusion was predominantly posterior, and in the other five, it extended laterally or inferiorly. The conventional echocardiographic signs of cardiac tamponade such as right atrial collapse, right ventricular diastolic collapse, and left atrial collapse were present in only 3, 1, and 3 of these 15 patients, respectively, but all exhibited left ventricular diastolic collapse. Increasing pressure within the compartment of a loculated pericardial effusion reaching the limit of pericardial distensibility and consequent transient reversal of transmural left ventricular pressure during diastole are most likely the basis for diastolic collapse of the thick-walled ventricle in a setting of regional cardiac tamponade. CONCLUSIONS: We conclude that left ventricular diastolic collapse is a frequent sign of regional cardiac tamponade and could be a useful marker of tamponade in postoperative patients.

Adult↗
PubMed1991

Intravascular ultrasound assessment of arterial dissection, intimal flaps, and intraarterial thrombi.

Arterial dissection, intimal tears, and intraluminal thrombosis are common sequelae of catheter-based interventional procedures for coronary artery disease. These may not be recognized reliably by contrast angiography. Intravascular ultrasound imaging is an innovative method that allows visualization of the cross-sectional anatomy with high-resolution real-time images. This article presents the recent experience in arterial imaging with this method. Studies documenting the ability of intravascular ultrasound to demonstrate arterial atherosclerosis and to unmask some problems related to atherosclerotic disease and its treatment by catheter-based maneuvers are presented. Problems of arterial dissection, intimal flaps, and intravascular thrombosis are described with in vitro and in vivo documentation of the capability of intravascular ultrasound to visualize these abnormalities. The clinical implications of real-time imaging of intimal flaps and intraluminal clots, and the possible value of this imaging modality in the performance of catheter-based therapeutic procedures for coronary and peripheral arterial disorders are discussed.

Angioplasty↗
PubMed1990

Real-time intravascular ultrasound imaging in humans.

The capability of obtaining cross-sectional, high resolution images of arteries with the use of ultrasound catheters has recently been demonstrated in animal studies. In this study the in vivo feasibility of intravascular ultrasound imaging in humans was evaluated. In 26 patients who had undergone diagnostic cardiac catheterization or iliofemoral arteriography, 1 of 3 different models of 20-MHz ultrasound catheters was advanced retrograde, into the iliac arteries and aorta or anterograde into the femoral arteries and real-time cross-sectional images of the arteries were obtained in all. In 10, the iliac arteries were normal and appeared circular and pulsatile with a 3-layered wall and crisply defined lumens. In 7 patients with nonobstructive plaques, the plaque was easily identified in the ultrasound image as a linear, bright, adynamic echo-dense structure. In 4 with obstructive disease in the iliac artery, the arterial lumen appeared irregular, bordered by a thickened, nonpulsatile wall. Variable grades of atheromatous abnormalities in the wall could be visualized. In all 5 patients with arteriographic evidence of obstructive disease of the femoral artery, intravascular ultrasound displayed reduced lumens and irregular borders with protruding high-intensity echoes in the wall. In all patients, the arterial lumen and the normal or abnormal wall were well visualized in the ultrasound images. There were no complications. This study thus demonstrates the feasibility of intravascular ultrasound imaging of arterial circulation in humans. With further improvements in catheter design and image quality, this imaging approach is likely to have a number of potential applications in the assessment of peripheral and coronary arterial diseases and in guiding interventional therapeutic procedures.

Aorta, Abdominal↗
PubMed1990

Intravascular and intracardiac ultrasound imaging: current research and future directions.

Intravascular and intracardiac ultrasound imaging is a newly emerging catheter-based imaging modality with considerable promise. This review article presents the rationale behind attempts at developing intravascular imaging methods, the design features of intravascular instrumentation, the knowledge obtained with in vitro studies, the in vivo experience in humans, and the potential applications of intravascular imaging in arterial atherosclerosis. The feasibility of pulmonary artery imaging and the potential applications of intracardiac echocardiography are discussed. Finally, future directions in intravascular imaging are outlined.

Blood Vessels↗
PubMed1990

Percutaneous balloon valvuloplasty and coronary angioplasty: what kind of guidance would be useful during the performance of these procedures?

Major advances have occurred during the last decade in the management of coronary arterial and valvular diseases using catheter-based treatment modalities. These methods, however, are still plagued by technical difficulties in the performance of the procedures because of the lack of appropriate guidance, and complications because of difficulties in patient selection. This review article deals with the various problems related to percutaneous balloon valvuloplasty and coronary angioplasty, outlines the specific needs in terms of guidance and discusses the possible guiding potential of intravascular ultrasound imaging methods.

Angioplasty, Balloon, Coronary↗
PubMed1990

Real-time intracardiac two-dimensional echocardiography: an experimental study of in vivo feasibility, imaging planes, and echocardiographic anatomy.

The traditional transthoracic and transesophageal echocardiographic examination have proven to be useful imaging tools for studying cardiac morphology, pathology, and function. Recently, catheter-based ultrasound transducers have been available for intravascular ultrasonic imaging. We supposed that echocardiographic examination performed from within the heart itself can provide useful information about cardiac structure and function, especially in settings where transthoracic or transesophageal echocardiography may be technically difficult to perform or poorly tolerated by the patient. To explore this concept, we performed intracardiac echocardiography in vivo in 22 dogs using both 5-MHz and 20-MHz transducers. High-quality images were obtained in all animals. Using the higher frequency transducer, detailed images with only a limited depth of field were obtained. With the 5-MHz transducer, a comprehensive cardiac examination was feasible from within the right atrium and inferior vena cava. We were able to visualize the great vessels, all cardiac valves, and cardiac chambers in a multitude of imaging planes. Alterations in ventricular function were instantly recognized. Color Doppler capabilities allowed visualization of flow abnormalities as well. We conclude that intracardiac echocardiography is feasible and could be potentially useful in certain clinical situations. With further research and development, this technique may have an important clinical impact in cardiac therapy and diagnosis.

Animals↗
PubMed1990

Problems and pitfalls in the performance and interpretation of color Doppler flow imaging: observations based on the influences of technical and physiological factors on the color Doppler examination of mitral regurgitation.

Color Doppler flow imaging has become an integral part of the echocardiographic examination. By providing real-time, two-dimensional spatial maps of normal and abnormal cardiac blood flows, this technique provides important information that may be used to guide patient management. The acquisition and display of color Doppler flow information may be influenced by technical factors, by the physiological condition of the patient, by abnormalities of cardiac morphology, and, on occasion, by artifact. In this article, the results of a study performed to evaluate the influence of technical factors on the color Doppler assessment of mitral regurgitation are reported. Mitral regurgitation jet area size changed significantly with variation in the control settings for color gain, color process, color map, color image resolution, and sector width. A review of those factors that influence the performance and interpretation of the color Doppler flow examination is provided and their significance discussed.

Echocardiography, Doppler↗
PubMed1990

Intracardiac, intravascular, two-dimensional, high-frequency ultrasound imaging of pulmonary artery and its branches in humans and animals.

Intravascular ultrasound imaging is a promising new method for assessing vascular morphology. We evaluated the capability of intravascular ultrasound to quantify pulmonary artery (PA) morphology in vitro and explored the feasibility of in vivo PA imaging in animals and humans. In the in vitro study of 15 PA segments, we used a 20-MHz prototype ultrasound catheter. Intravascular ultrasound (y) provided crisp images of PA segments and demonstrated excellent correlations with anatomic measurements (x) in the estimation of luminal area (y = 0.89x + 2.95, r = 0.99, p less than 0.001), luminal diameter (n = 30, y = 0.79x + 0.96, r = 0.92, p less than 0.001), and vessel wall thickness (n = 60, y = 0.65x + 0.33, r = 0.85, p less than 0.001). We subsequently introduced the probe into the PA of 10 dogs and were able to obtain real-time, two-dimensional images of the main PA, its major branches, and farther smaller branches as far as the wedge level. To evaluate the in vivo feasibility of PA imaging in conscious humans, we used a commercially available, 20-MHz intravascular ultrasound (IVUS) catheter in 22 subjects through a femoral or jugular venous sheath at the end of standard diagnostic cardiac catheterization. In 20 subjects, we acquired dynamic, high-resolution, cross-sectional images of the proximal and distal PA. Changes in shape and decreasing luminal area could be clearly recognized as the IVUS catheter reached branching points and as it passed more distally. There were no complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Constrictive pericarditis.

Constrictive pericarditis is a complex disorder characterized by abnormal thickening of the pericardium that leads to pathologic changes in cardiac hemodynamic data. The disorder can be suspected by history and physical findings. Data from echocardiography, CT, and MRI offer diagnostic information. The diagnosis cannot generally be established with certainty by noninvasive methods. Additional information from cardiac catheterization may help confirm the diagnosis. Together, these diagnostic modalities aid in the assessment of disease and help to differentiate it from related conditions such as restriction, cardiac tamponade, and right ventricular infarction. Treatment is largely surgical, and new techniques and approaches have made it relatively safe. Early diagnosis and pericardiectomy may lead to cure in most patients.

Cardiac Catheterization↗
PubMed1989

Effects of atrial cardioplegia on the ischemic right ventricle after acute coronary artery occlusion and reperfusion.

Right atrial cardioplegia has been advocated as a simple method of delivering retrograde cardioplegia. Passive distention of the right heart inherent with right atrial cardioplegia has been shown to impair right ventricular function in a canine model of global ischemia. This study was designed to compare right ventricular performance after right atrial cardioplegia administered intermittently (n = 5) and continuously (n = 5) with coronary sinus retrograde cardioplegia (n = 5) and aortic root cardioplegia (n = 8) in a canine model of acute right ventricular ischemia and reperfusion. Right ventricular performance was assessed using the load-independent relationship of end-systolic pressure versus dimension (myocardial fiber length). Right ventricular performance was well preserved after reperfusion in those dogs protected with intermittent right atrial cardioplegia (95% of control). Results with continuous right atrial cardioplegia (66% of control) and coronary sinus retrograde cardioplegia (40% of control) demonstrated diminished postreperfusion right ventricular performance. Right ventricular performance in the group protected with aortic root cardioplegia was significantly impaired after reperfusion when compared with all retrograde groups (34% of control, p less than 0.05). In this model, postreperfusion right ventricular performance was preserved in the right atrial cardioplegia groups despite passive ventricular distention. All methods of retrograde cardioplegia resulted in superior preservation of right ventricular performance when compared with standard aortic root cardioplegia.

Animals↗
PubMed1989

Clinical and hemodynamic performance of the Ionescu-Shiley valve in the small aortic root. Results in 117 patients with 17 and 19 mm valves.

The Ionescu-Shiley pericardial valve was our bioprosthetic valve of choice between 1981 and 1985 for patients in whom the aortic anulus could not accept a valve larger than 19 mm in outer diameter or in whom the avoidance of warfarin sodium (Coumadin) was important. A series of 117 consecutive patients who received 17 or 19 mm valves for isolated aortic valve replacement or aortic valve replacement combined with coronary artery bypass grafting or other valvular procedures was analyzed. Overall, 74% of the patients were female, with a mean age of 70.9 years and a body surface area of 1.67 +/- 0.19 m2; 92.3% were in New York Heart Association class III-IV, and the operation was urgent or emergent in 46%. The operative mortality rate was 7.7%, with no deaths in patients undergoing isolated elective first-time aortic valve replacement. Mean follow-up for survivors was 2.5 years (10 to 62 months). There were 20 late deaths, of which three were valve related, three were due to sudden death or arrhythmias, and two were due to persistent heart failure. The actuarial survival rate at 5 years was 68%. Clinical follow-up revealed a low incidence of valve-related complications, and 96.4% of survivors were in class I-II. Postoperative echocardiography before hospital discharge revealed a maximum instantaneous gradient of 18.4 +/- 3.0 mm Hg in five patients having a 17 mm valve and 31.3 +/- 12.7 mm Hg in 20 patients having a 19 mm valve. Doppler echocardiography was performed in 22 patients at a mean follow-up of 39.3 +/- 11.7 months. The maximum instantaneous gradient was 25 +/- 17.2 mm Hg for 17 mm and 17.41 +/- 5.4 mm Hg for 19 mm valves at late follow-up. The effective orifice area was 0.85 +/- 0.1 cm2 for 17 mm and 1.21 +/- 0.21 cm2 for 19 mm valves. This study defines the normal range of Doppler echocardiographic transprosthetic gradients for the Ionescu-Shiley valve and confirms that low operative mortality and excellent clinical improvement can result from the use of small Ionescu-Shiley valves in elderly patients despite moderate postoperative transvalvular gradients.

Adult↗