PubMed Health⌕ Search

Biomedical subjects

Natesa G Pandian

Publications and source records attributed to Natesa G Pandian.

At least 37 records · Page 2Linked to original sources
PubMed2005

Doppler tissue imaging improves assessment of abnormal interventricular septal and posterior wall motion in constrictive pericarditis.

We hypothesized that Doppler tissue imaging in the short axis would provide enhanced quantitative information for differentiating the pattern and extent of abnormal septal and posterior wall motion in constrictive pericarditis (CP). Using quantitative pulsed wave and color M-mode Doppler tissue imaging, we quantified the pattern of abnormal septal and posterior wall motion and studied its incremental advantage over conventional M-mode and 2-dimensional echocardiography in 40 patients with surgically proven CP. The pattern and extent of abnormalities were compared with 35 age- and sex-matched control subjects and 20 patients with abnormal septal motion of other causes. In 33 patients (82.5%) with CP, the interventricular septum showed high-velocity (>7 cm/s) early diastolic biphasic motion with or without multiple recoil waves (polyphasic diastolic septal fluttering). In the posterior wall, the early diastolic wave was normal but the late diastolic wave was reduced in 24 patients (60%) and absent in 7 (17.5%). In comparison, M-mode and 2-dimensional echocardiography identified abnormal septal or posterior wall motion in 24 patients (60%) ( P = .003). The pattern of abnormal septal motion in CP could be differentiated from abnormal septal motion of other causes in 16 patients (80%). The overall sensitivity and specificity of high-velocity polyphasic septal flutter for differentiating CP from control cases and other diseases was 82.5% and 92.7%, respectively. In CP, Doppler tissue imaging in the short axis provides unique diagnostic information and reliably differentiates CP from control cases and most other causes of abnormal septal motion.

Adult↗
PubMed2004

Echocardiographic evidence of left atrial abnormality in young patients with lone paroxysmal atrial fibrillation.

Usual assessment of left atrial size by 2-dimensional echocardiography in the anteroposterior dimension often underestimates the true atrial size. We compared 15 young patients (< or =50 years old) with lone paroxysmal atrial fibrillation to age-matched controls, and measured atrial size in the inferosuperior and mediolateral dimensions. These additional measurements and atrial volumes were significantly increased compared with control patients, revealing that patients with apparent "lone" paroxysmal atrial fibrillation may have subtle structural abnormalities of the left atrium.

Adult↗
PubMed2004

Comparison of echocardiographic features of noncompaction of the left ventricle in adults versus idiopathic dilated cardiomyopathy in adults.

Noncompaction of left ventricular myocardium (NCLV), or "spongy myocardium," in adults represents an arrest in endomyocardial morphogenesis and occurs as an isolated cardiomyopathy. Because NCLV can be readily mistaken for idiopathic dilated cardiomyopathy, echocardiographic features other than the structural features of the myocardial wall need to be carefully defined for distinguishing the 2 conditions. This study was therefore designed to characterize the echocardiographic features that could be useful for differentiating NCLV from idiopathic dilated cardiomyopathy.

Adult↗
PubMed2004

Accuracy and pitfalls of early diastolic motion of the mitral annulus for diagnosing constrictive pericarditis by tissue Doppler imaging.

Mitral annular velocities are reportedly useful in diagnosing constrictive pericarditis (CP); however, their exact efficacy in larger clinical settings remains unevaluated. This study reexamined the role of longitudinal tissue Doppler imaging in diagnosing CP in clinical practice. Tissue velocity imaging (GE Vingmed System Five) was performed in 122 subjects (87 referred with clinically suspected CP and 35 age- and sex-matched controls). Of the 87 subjects with suspected CP, 45 (51.7%) had CP confirmed at surgery, 11 (12.6%) had restrictive heart disease, 20 (23.0%) had right heart failure due to cor pulmonale, and the other 11 (12.6%) had old pericardial effusions and no hemodynamic evidence of constriction on follow-up echocardiography. Of the 45 patients with CP, mitral early diastolic (Ea) annular velocities from septal and lateral regions were normal (>/=8 cm/s) in 40 (88.9%) and decreased (<8 cm/s) in 1 or both regions in 5 (3 with left ventricular systolic dysfunction, 2 with extensive mitral annular calcification). Of 11 patients with restrictive cardiomyopathy, 8 (72.7%) had reduced Ea (<8 cm/s) and 3 showed normal Ea velocity in 1 or both corners of the mitral annulus. All except 2 patients with right-sided heart failure from cor pulmonale and those with previous pericardial effusion had normal Ea velocities. A normal Ea velocity improved recognition of CP, particularly in the presence of nondiagnostic 2-dimensional or transmitral flow-Doppler imaging. The overall sensitivity and specificity for diagnosing CP using tissue Doppler incrementally with M-mode, 2-dimensional, and transmitral flow Doppler were 88.8% and 94.8%, respectively. Mitral annular velocities help with diagnosis and differentiation of CP in most cases, except in the presence of extensive annular calcification, left ventricular systolic dysfunction, or segmental nonuniformity in myocardial velocities.

Adult↗
PubMed2004

Does chronic mitral regurgitation influence Doppler pressure half-time-derived calculation of the mitral valve area in patients with mitral stenosis?

BACKGROUND: In patients with mitral stenosis (MS), Doppler pressure half-time (PHT) may be influenced by hemodynamic variables other than the anatomic mitral valve orifice narrowing. This study was undertaken to assess whether the presence of concomitant mitral regurgitation (MR) affects mitral valve area (MVA) estimation by PHT. METHODS: Consecutive patients (n = 166) with noncalcific MS, in sinus rhythm, were studied. Group 1 (n = 106) had no or mild MR, and group 2 (n = 60) had moderate or severe MR. MVA was assessed by using the PHT method and planimetry. RESULTS: There was a strong correlation between planimetry and PHT MVA in both groups (group 1: r = 0.86, P <.001; group 2: r = 0.73, P <.001). However, compared with planimetry MVA, PHT underestimated MVA by > or =20% in 18 patients (17%) in group 1 and 21 patients (35%) in group 2 (P <.01). Overestimation by > or =20% occurred in 12 patients (11%) in group 1 and in 7 (12%) in group 2. Group 2 subanalysis (group 2A: moderate MR, n = 16; group 2B: severe MR, n = 44) revealed that linear regression weakened with increasing severity of MR (group 2A: r = 0.824, P <.001, group 2B: r = 0.70, P <.001). PHT underestimation of MVA occurred in 31% and 36% of patients in Groups IIA and IIB, respectively (P = NS). CONCLUSIONS: PHT appears to be reliable for estimating MVA in most patients with MS, even in the presence of MR. However, the presence of significant MR reduces the reliability of PHT-derived MVA, with underestimation of MVA in a significant number of subjects. The severity of MR has a direct impact on PHT-derived MVA.

Adolescent↗
PubMed2004

Clinical applications of contrast echocardiography.

Advances in the engineering of transpulmonary ultrasound contrast agents have greatly enriched contemporary two-dimensional (2D) echocardiography, a technique that has became the most commonly employed imaging tool in cardiology. The currently approved application of contrast echocardiography is far left ventricular opacification (LVO) and enhanced endocardial border delineation (EBD) in patients with sub-optimal echocardiograms. In addition, the use of contrast echocardiography in clinical practice allows blood-flaw assessment, identification of geometric distortions (such as an aneurysm or a pseudoaneurysm), and differentiation of various mass formations (such as thrombus, tumor, or simple trabeculation). Ongoing scientific work paints to the potential of contrast echocardiography in assessing myocardial perfusion and in using contrast agents in therapeutic maneuvers. The use of modern contrast agents in echocardiography can shorten examination time, improve diagnostic accuracy, eliminate unnecessary tests, and lower medical costs. In fact, qualitative or quantitative assessment of cardiac function is difficult to achieve without the improved visualization provided by contrast enhancement.

Contrast Media↗
PubMed2003

Relation between high-density lipoprotein cholesterol and peripheral vasomotor function.

Low levels of high-density lipoprotein (HDL) cholesterol are one of the most common lipid abnormalities in patients with coronary artery disease. Endothelial dysfunction is also highly prevalent in patients with coronary artery disease. We sought to determine whether HDL cholesterol levels are correlated with endothelium-dependent vasomotion in patients being evaluated for atherosclerosis. Peripheral vascular endothelial function was assessed by high-resolution brachial artery ultrasound. Flow-mediated dilation (FMD) during reactive hyperemia was defined as the percent change in arterial diameter following 5-minute arterial occlusion. All patients underwent stress testing with nuclear single-photon emission computed tomographic imaging to determine percent left ventricular ejection fraction and define the presence or absence of coronary artery disease. One hundred fifty-one subjects (87 men, 64 women) were enrolled (average age 58 +/- 11 years). Total cholesterol, HDL cholesterol, low-density lipoprotein cholesterol, and triglyceride levels were 188 +/- 48, 47 +/- 13, 108 +/- 37 and 154 +/- 88 mg/dl, respectively. The mean FMD for the entire group was 9.9 +/- 5.2%. Subjects with an HDL cholesterol of <40 mg/dl (n = 39) had lower FMD (7.4 +/- 3.6%) compared with those with an HDL cholesterol >/=40 mg/dl (11.0 +/- 5.5%, p <0.001). There was a significant correlation between FMD and HDL cholesterol level (linear regression, p <0.001), and in multivariate analysis, HDL cholesterol was an independent predictor of FMD. Peripheral endothelial function was abnormal in subjects with low HDL cholesterol and well-preserved in those with high HDL cholesterol. These data suggest that impaired endothelial function associated with low HDL cholesterol may be an additional, previously unrecognized mechanism contributing to the increased risk of atherosclerosis in these patients.

Age Factors↗
PubMed2003

Percutaneous mitral valve repair: a feasibility study in an ovine model of acute ischemic mitral regurgitation.

Annuloplasty is the cornerstone of surgical mitral valve repair. A percutaneous transvenous catheter-based approach for mitral valve repair was tested by placing a novel annuloplasty device in the coronary sinus of sheep with acute ischemic mitral regurgitation. Mitral regurgitation was reduced from 3-4+ to 0-1+ in all animals (P < 0.03). The annuloplasty functioned by reducing septal-lateral mitral annular diameter (30 +/- 2.1 mm preinsertion vs. 24 +/- 1.7 mm postinsertion; P < 0.03). These preliminary experiments demonstrate that percutaneous mitral annuloplasty is feasible. Further study is necessary to demonstrate long-term safety and efficacy of this novel approach.

Animals↗
PubMed2003

Assessment of peripheral vascular endothelial function with finger arterial pulse wave amplitude.

BACKGROUND: Abnormalities in pulse wave amplitude (PWA) have been described in subjects with atherosclerosis and may be a marker of future cardiac events. We evaluated the relationship between changes in PWA of the finger and peripheral endothelial function. METHODS: We performed measurements of PWA with a novel finger plethysmograph (peripheral arterial tonometry [PAT]) and compared the findings with a simultaneous noninvasive measurement of peripheral endothelial function with brachial artery ultrasound scanning (BAUS) in 89 subjects. The PAT hyperemia ratio was defined as the ratio of PWA during reactive hyperemia relative to the baseline. Flow-mediated dilation (FMD) was defined by BAUS as the ratio of the brachial artery diameter during reactive hyperemia relative to the baseline. Sixty-eight subjects underwent exercise myocardial perfusion imaging (ExMPI). RESULTS: Fifty-four men and 35 women were examined. There was a linear relationship between the PAT hyperemia ratio and FMD during the same episode of reactive hyperemia (r = 0.55, P <.0001). Subjects in the lowest FMD quartile had the lowest PAT hyperemia ratio, whereas subjects in the highest FMD quartile had the highest PAT hyperemia ratio (P <.001 for trend). Similar to BAUS, the PAT hyperemia ratio was more impaired in subjects with cardiovascular risk factors and in subjects with ExMPI studies that were indicative of coronary artery disease. CONCLUSIONS: Assessment of PWA with PAT demonstrates patterns of abnormality similar to that of BAUS assessment of FMD. PWA during reactive hyperemia is influenced by factors known to affect endothelial function, including cardiovascular risk factors and coronary artery disease. These findings support the concept that analysis of PWA with PAT during reactive hyperemia may be used to study peripheral vascular endothelial function.

Blood Pressure↗
PubMed2003

Tissue Doppler analysis is hindered in abnormal wall motion and changes in afterload.

BACKGROUND: Tissue Doppler (TD) analysis is used to estimate contractility. However, interference with hemodynamics has not been investigated. OBJECTIVE: To evaluate the effect of hemodynamic conditions and wall motion abnormalities on TD indices. METHODS: TD indices were obtained in 16 dogs and correlated with hemodynamics and wall thickening. RESULTS: An inverse relation between TD indices and systemic vascular resistance was observed when afterload-related parameters were included in the analysis (early systolic subendocardial velocity: r((multiple regression))=0.82, P<0.0001 vs. r((simple regression))=0.57, P=0.0002). Early systolic TD data were more closely related to hemodynamics than those derived from the entire systole. TD data did not correspond to the hyperkinesia of the contralateral wall in myocardial infarction, whereas the increase of gradient parameters reflected hypercontractility (P<0.05). CONCLUSION: TD indices are directly related to contractility and inversely to afterload. They do not reflect wall motion of those segments not involved in regional ischemia.

Animals↗
PubMed2003

Effects of angiotensin II receptor blockade versus angiotensin-converting-enzyme inhibition on ventricular remodelling following myocardial infarction in the mouse.

Left ventricular (LV) remodelling following myocardial infarction (MI) is associated with increased morbidity and mortality. Previous data suggest that angiotensin II (Ang II) plays a central role in the molecular events contributing to LV remodelling. We explored the effects of angiotensin-converting-enzyme (ACE) inhibition versus Ang II (AT(1)) receptor blockade on LV remodelling in mice post-MI. Mice underwent sham procedure or left coronary artery ligation, and received placebo, the AT(1) receptor antagonist, losartan or the ACE inhibitor, enalapril. At 6 weeks, echocardiography and haemodynamic studies were performed. Infarct size and interstitial collagen content were determined. Expression of genes encoding atrial natriuretic peptide (ANP), collagen type I, AT(1a) and AT(1b) receptors were measured. The placebo MI group showed increased LV end-diastolic diameter, LV end-systolic diameter with depressed fractional shortening ( P <0.01 versus shams), increased LV mass and volume (both P <0.01 versus shams). The placebo MI group also exhibited increased non-infarct zone collagen content ( P <0.01), ANP ( P <0.01) and collagen type 1 ( P <0.01) gene expression, with a non-significant rise in AT(1a) receptor gene expression. Neither losartan or enalapril prevented LV dilation or improved fractional shortening. Both similarly lowered systolic blood pressure ( P <0.01 for each versus placebo). Losartan and enalapril inhibited LV hypertrophy ( P <0.01), and decreased ANP ( P <0.01) and collagen type 1 gene expression ( P <0.05). Levels of AT(1a) receptor gene expression were higher than shams ( P <0.05 for both), but similar to placebo. AT(1b) receptor gene expression was much lower than that for AT(1a) receptor and similar in all groups. Thus, in this model, AT(1) receptor antagonism and ACE inhibition have equivalent inhibitory effects on myocardial hypertrophy and fibrosis. These results serve as an important basis for planned investigations to evaluate the anti-remodelling effects of these agents on mice in which genetic manipulations are used to disrupt components of the Ang II signalling system.

Angiotensin Receptor Antagonists↗
PubMed2003

Automated external defibrillator arrhythmia detection in a model of cardiac arrest due to commotio cordis.

INTRODUCTION: Cardiac arrest due to chest wall blows (commotio cordis) has been reported with increasing frequency in children, and only about 15% of victims survive. Automated external defibrillators (AEDs) have been shown to be life saving in adults with cardiac arrest, but data on their use in children are limited. In a swine model of commotio cordis designed to be most relevant to young children, we assessed the efficacy of a commercially available AED for recognition and termination of ventricular fibrillation. METHODS AND RESULTS: Ventricular fibrillation was produced in anesthetized juvenile swine by precordial impact from a baseball under controlled conditions. Animals were randomized to defibrillation after 1, 2, 4, or 6 minutes of ventricular fibrillation. Twenty-six swine underwent 50 ventricular fibrillation inductions. Sensitivity of the AED for recognition of ventricular fibrillation was 98%, and specificity for nonshockable episodes was 100%. All episodes of ventricular fibrillation were successfully terminated by the AED. CONCLUSION: In this experimental model of commotio cordis, the AED proved to be highly sensitive and specific for recognition of ventricular fibrillation and effective in terminating the arrhythmia and restoring sinus rhythm. These findings suggest that early defibrillation with the AED could save young lives on the athletic field.

Animals↗
PubMed2003

Role of echocardiography in the diagnosis and treatment of patients with aortic stenosis.

PURPOSE OF REVIEW: Echocardiographic assessment plays a major role in the evaluation of aortic stenosis (AS). Because of its proven accuracy, ease of applicability, and safety, it is replacing cardiac catheterization for the assessment of AS in many centers. RECENT FINDINGS: In this review, we discuss the basic principles of echocardiographic assessment of AS and clinically challenging scenarios including AS with low cardiac output state or other structural heart disease. Dobutamine stress echocardiography is a useful tool for assessing low cardiac output AS. The role of transesophageal echocardiography in the evaluation of AS is also reviewed. SUMMARY: Echocardiographic techniques provide critical information in the assessment of patients with known or suspected AS and guide decision-making regarding the appropriateness of valve replacement.

Aortic Valve↗
PubMed2002

Is the mitral valve area flow-dependent in mitral stenosis? A dobutamine stress echocardiographic study.

OBJECTIVES: The purpose of this study was to compare the effect of changes in flow rate on the mitral valve area (MVA) derived from two-dimensional echocardiographic planimetry and Doppler pressure half-time (PHT) methods in patients with mitral stenosis (MS). BACKGROUND: Dobutamine stress echocardiography has been proposed as a means of assessing the severity of MS. However, data regarding the effect of an increase in flow rate on MVA are limited. If MVA is indeed flow-dependent, this has important implications for the assessment of the severity of MS, particularly in the setting of reduced cardiac output (CO). METHODS: Dobutamine echocardiography was performed in 57 patients with isolated MS who were in sinus rhythm. The MVA was determined by planimetry and Doppler PHT methods. RESULTS: Cardiac output increased by > or =50% in 27 patients (group I) and by <50% in 30 patients (group II). In group I, the MVA by planimetry increased by only 10.6 +/- 2% and the MVA by PHT increased by 21.9 +/- 4.8%. These changes were similar to those observed in group II (10.7 +/- 3% and 14.8 +/- 4%, respectively; p = NS), despite a much smaller increase in CO. A clinically important change (from the severe to mild category) occurred in only one patient when using the PHT method and in none by planimetry. CONCLUSIONS: Changes in flow rate result in small but clinically insignificant changes in echocardiographic MVA measurement. These methods provide an accurate assessment of MS severity in a majority of patients, independent of changes in flow rate.

Adolescent↗
PubMed2002

Therapeutic ultrasound in cardiology.

Ultrasound can be exploited to derive therapeutic results by using its bioeffects such as creation of mechanical vibrations, localized cavitations, microstream formation, physicochemical changes and thermal energy. Extensive in vitro and animal investigations during the last 2 decades have laid a foundation for ultrasound energy to be used for treatment purposes in various medical specialties. In the area of cardiovascular diseases, ultrasound could be used for thrombolysis, adjunct to coronary interventions, drug delivery, local gene transfer, and creating therapeutic lesions. The dispensation approaches to therapeutic ultrasound are varied, from the use of low- to medium-range frequency, low to focused high intensity, and catheter-based to external devices. Catheter-based ultrasound could be useful for intracoronary thrombolysis, and external ultrasound instrument with transcutaneous delivery could be of use in applications such as creation of myocardial lesions, peripheral vessel thrombolysis, and drug and gene delivery. Adjunct administration of microbubbles has been found to enhance thrombolysis, and drug and gene therapy. Ongoing studies strongly suggest that therapeutic ultrasound could have an important role in cardiovascular disorders associated with thrombosis, inflammation, atherosclerotic disease, and arrhythmias.

Animals↗
PubMed2002

Myocardial perfusion imaging using contrast echocardiography.

BACKGROUND: Intense work during the last two decades has brought forth the use of myocardial contrast echocardiography to the clinical threshold for the diagnosis and evaluation of coronary artery disease. CLINICAL USE: A number of ultrasound contrast agents have been developed that act as red blood cell tracers and display myocardial perfusion when imaged by dedicated ultrasound imaging modalities. A considerable amount of experimental and clinical research has shown that myocardial contrast echocardiography can aid in the recognition of acute and chronic myocardial infarction, viable myocardium, and functionally significant coronary stenoses. Comparison of this technique to nuclear imaging and coronary arteriography has demonstrated excellent diagnostic accuracy in the evaluation of various coronary syndromes. Optimal practice of perfusion imaging requires a thorough knowledge of microbubble characteristics and imaging modalities, as well as good experience in the method. PERSPECTIVES: The technique continues to evolve from intermittent gated examination to real-time perfusion imaging that allows evaluation of both perfusion and functional parameters. The opportunity to target sites of pathology with specially engineered microbubbles could also aid in many therapeutic applications besides diagnostic imaging.

Animals↗
PubMed2002

Recent role of imaging in the diagnosis of pericardial disease.

Noninvasive cardiac imaging techniques have made a striking impact on the evaluation and management of pericardial disorders. Two-dimensional and Doppler echocardiography are the methods of choice in the evaluation of pericardial effusion and cardiac tamponade. Magnetic resonance imaging, computed tomography, and transesophageal echocardiography are valuable in the assessment of pericardial thickness in suspected cases of constrictive pericarditis. Filling dysfunction associated with constrictive pericarditis is well demonstrated by Doppler flow velocity recordings of intracardiac flow jets, and pulmonary and hepatic venous flow streams. Tissue Doppler echocardiography, by which tissue velocity of myocardial regions and mitral annulus are analyzed, offers additional information in the differentiation of constrictive pericarditis and restrictive cardiomyopathy. Magnetic resonance imaging and computed tomography are the techniques of choice in the recognition of unusual disorders such as pericardial cysts, tumors invading the pericardium, and congenital absence of pericardium. Noninvasive imaging aids not only in the diagnosis of pericardial diseases, but also in the guidance of optimal therapy.

Blood Flow Velocity↗