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Biomedical subjects

A Lahiri

Publications and source records attributed to A Lahiri.

At least 55 records · Page 3Linked to original sources
PubMed2000

Can nuclear cardiology really help in the emergency departments of the 21st century?

The cardiac troponins are a highly sensitive and specific marker for myocardial damage and have been shown to be useful in the management of patients with acute coronary syndromes. However, some patients with significant ischaemia have no myocardial damage, and therefore negative troponins, despite high risk of subsequent events. Furthermore as a result of the time delay before the troponins can be measured in the peripheral blood, serial sampling is required to rule out myocardial damage. Nuclear perfusion imaging provides an instantaneous assessment of perfusion at the time of injection which is not dependent of on myocardial necrosis, but the presence of flow heterogeneity. Thus these two techniques provide complementary information for the assessment of patients with chest pain and non-diagnostic electrocardiograms, and early perfusion imaging offers the possibility of more rapid assessment and decision making than is possible with troponins.

Acute Disease↗
PubMed2000

Infective disorders.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1999

Prediction of coronary and cerebrovascular morbidity and mortality by direct continuous ambulatory blood pressure monitoring in essential hypertension.

BACKGROUND: The goal of this study was to assess the prognostic value of ambulatory versus clinic blood pressure measurement and to relate cardiovascular risk to ambulatory systolic and diastolic blood pressure levels. METHODS AND RESULTS: The study population consisted of 688 patients 51+/-11 years of age who had undergone pretreatment 24-hour intra-arterial ambulatory blood pressure monitoring on the basis of elevated clinic blood pressure. A total of 157 first events were recorded during a 9.2+/-4.1-year follow-up period. The predictive value of a regression model containing age, sex, race, body mass index, smoking, diabetes mellitus, fasting cholesterol level, and previous history of cardiovascular disease was significantly improved by the addition of any ambulatory systolic or diastolic blood pressure parameter (whether 24-hour, daytime, or nighttime mean) or pulse pressure, whereas inclusion of baseline clinic blood pressure variables did not enhance the prediction of events. The most predictive models contained the ambulatory systolic blood pressure parameters. In the model containing 24-hour mean ambulatory systolic blood pressure (P=0.001), age (P<0.001), male sex (P<0.001), South Asian origin (P=0.008), diabetes mellitus (P=0. 05), and previous cardiovascular disease (P<0.001) were additional independent predictors of events. Whereas 24-hour ambulatory systolic blood pressure was linearly related to the incidence of both coronary and cerebrovascular events, 24-hour ambulatory diastolic blood pressure exhibited a positive linear relationship with cerebrovascular events but a curvilinear relationship with coronary events. CONCLUSIONS: Ambulatory blood pressure is superior to clinic measurement for the assessment of cardiovascular risk; there is no reduction in coronary risk at lower levels of ambulatory diastolic blood pressure.

Adult↗
PubMed1999

Comparison of safety and efficacy of carvedilol and metoprolol in stable angina pectoris.

In a double-blind, randomized, 3-month multicenter study, the safety and tolerability and the antianginal and anti-ischemic efficacy of carvedilol 25 to 50 mg twice daily were assessed in comparison with metoprolol 50 to 100 mg twice daily in younger and elderly patients with stable angina. After a 7-day placebo run-in at the end of which a symptom-limited bicycle ergometric exercise was performed, 368 patients were randomly allocated to the parallel treatment groups. After 4 weeks of therapy with a low dose, a further exercise test was performed and patients were titrated in single-blind fashion to the higher dose if the increase in total exercise time was < 1 minute, and there was no safety concern. After a further 8 weeks of treatment a third exercise test was performed. Carvedilol low dose/high dose was shown to be at least as safe and well tolerated as metoprolol low dose/high dose both in younger and elderly patients. There were no hitherto unknown adverse events and no marked change in the types of events after increase of the doses. Early adverse events after treatment initiation or uptitration were equal with both medications, indicating no particular risk associated with carvedilol's vasodilatory action. No rebound phenomena were observed. Both drugs showed good antianginal and anti-ischemic efficacy, with marked increases on uptitration including patients > or = 65 years of age. However, in the doses selected, which appeared equipotent with respect to beta blockade, carvedilol's improvement of time to 1-mm ST-segment depression was statistically significantly greater than that of metoprolol. This could be due to its additional vasodilatory or antioxidative actions. Based on the safety and efficacy data of the present study, use of the higher of the 2 recommended doses of carvedilol and metoprolol appears justified in younger and elderly patients without adequate therapeutic control at lower doses.

Adrenergic alpha-Antagonists↗
PubMed1999

Carvedilol prevents remodeling in patients with left ventricular dysfunction after acute myocardial infarction.

OBJECTIVE: The aim of the study was to assess the effects of carvedilol, a vasodilating nonselective beta-blocker, on the indexes of left ventricular remodeling after acute myocardial infarction in those with left ventricular dysfunction. METHODS AND RESULTS: Forty-nine patients with predischarge left ventricular ejection fraction <45% after acute myocardial infarction were evaluated in a double-blind, randomized, placebo-controlled, parallel group study (selected from the database of the Carvedilol Heart Attack Pilot Study: CHAPS). Patients received medication after thrombolysis and continued to do so for 6 months. Two-dimensional echocardiography was performed before discharge (7 to 10 days after admission) and at 3 months after acute myocardial infarction. Analysis of variance showed that wall thickness opposite the site of infarction decreased from (mean +/- SD) 12.3 +/- 2.1 mm to 11.0 +/- 2.4 mm with carvedilol compared with 11.6 +/- 1.9 mm to 12.2 +/- 1.9 mm with placebo (P =.01). Left ventricular mass changed from 235 +/- 74 g to 217 +/- 64 g with carvedilol compared with 227 +/- 80 g to 252 +/- 85 g with placebo ( P =.02). Carvedilol prevented alteration of sphericity index (ratio of long and short axis of left ventricle) that changed from 1.65 +/- 0.29 to 1.66 +/- 20 with carvedilol compared with 1.58 +/- 0.33 to 1.39 +/- 0.19 with placebo (P =.02); alteration was also prevented of wall thickening abnormality at infarct site, which changed from 9.2 +/- 3.1 cm2 to 9.1 +/- 3.5 cm 2 with carvedilol compared with 10.3 +/- 3.3 cm2 to 13.5 +/- 4.6 cm2 with placebo (P =.002). CONCLUSION: Carvedilol administered early after acute myocardial infarction results in attenuation of left ventricular remodeling in patients with persistent left ventricular dysfunction before discharge.

Adrenergic beta-Antagonists↗
PubMed1999

Improved endocardial visualization with second harmonic imaging compared with fundamental two-dimensional echocardiographic imaging.

BACKGROUND: Endocardial visualization is suboptimal by fundamental imaging in at least 30% of patients. Second harmonic imaging was developed for visualization of myocardial contrast agents. We have hypothesized that endocardial visualization may improve with harmonic imaging compared with fundamental imaging. METHODS AND RESULTS: Accordingly, 40 consecutive patients with poor endocardial visualization by conventional echocardiography in at least 1 left ventricular segment (22-segment model) in the 4 standard views randomly underwent fundamental and harmonic imaging without contrast. The images were separately and randomly analyzed by 2 observers. Endocardial visualization was scored as 0, not visualized; 1, poorly visible; and 2, well visualized. Endocardial visualization indexes were also calculated. More segments were assigned a score of 0 (P <. 001) and 1 (P <.001) by fundamental compared with harmonic imaging, whereas harmonic imaging demonstrated more segments with a score of 2 (P <.001) compared with fundamental imaging. Endocardial visualization indexes were significantly better by harmonic imaging in the parasternal long axis (P <.005), short axis (P <.001), and apical 4- (P <.0001) and 2-chamber views (P <.0001). Similar results were obtained by a second observer. Agreement between the 2 observers regarding improvement, deterioration, or no change in score between harmonic and fundamental imaging was 88% (kappa = 0. 76). Interobserver and intraobserver agreements for systolic wall thickening scores also significantly improved with harmonic compared with fundamental imaging (P <.001). CONCLUSION: Second harmonic imaging is superior to fundamental imaging for endocardial visualization in patients with suboptimal fundamental imaging.

Coronary Disease↗
PubMed1999

Myocardial viability on echocardiography predicts long-term survival after revascularization in patients with ischemic congestive heart failure.

OBJECTIVES: This study was conducted to evaluate the effect of revascularization on survival in patients with congestive heart failure (CHF) due to ischemic left ventricular (LV) systolic dysfunction based on the presence of myocardial viability (MV). BACKGROUND: There are insufficient data regarding the survival benefit of revascularization in patients with CHF due to ischemic LV systolic dysfunction. METHODS: Follow-up was obtained in 87 consecutive patients with CHF due to ischemic LV systolic dysfunction (New York Heart Association [NYHA] class II-IV; LV ejection fraction <0.35) who underwent low-dose dobutamine echocardiography (DE). MV within each of 12 myocardial segments representing the LV was defined as having either: 1) normal function or mild dyssynergy at rest; 2) severe resting dyssynergy that improved on DE, or 3) worsening of function on DE except in the case of akinesia. RESULTS: At a mean follow-up of 40+/-17 months, 37 patients had received revascularization on the basis of clinical grounds, and there were 22 (25%) cardiac-related deaths. Multivariate Cox regression analysis revealed that when patients with at least five segments showing MV underwent revascularization, mortality was reduced by an average of 93% (confidence interval of 22% to 99%), which was associated with improvement in NYHA class as well as LV ejection fraction. Patients with less than five segments showing MV who underwent revascularization (and thus, showing mostly scar), and those with at least 5 segments demonstrating MV who were treated medically, had a much higher mortality. CONCLUSIONS: Revascularization produces a clear survival benefit in patients with CHF due to ischemic LV systolic dysfunction who have a significant region of the LV demonstrating MV. These data may have wide-ranging implications in the management of patients with coronary artery disease whose main clinical presentation is CHF.

Adult↗
PubMed1999

The carvedilol hibernation reversible ischaemia trial; marker of success (CHRISTMAS). The CHRISTMAS Study Steering Committee and Investigators.

BACKGROUND: Carvedilol improves left ventricular (LV) function when heart failure is due to LV systolic dysfunction, but the magnitude of the response is heterogeneous among patients with coronary disease, possibly reflecting the presence or volume of hibernating myocardium. AIMS: The primary objective of the study is to determine whether the presence of hibernating myocardium predicts the magnitude of improvement in LV ejection fraction in response to carvedilol among patients with heart failure and LV systolic dysfunction due to coronary disease. METHODS: The study is a prospective, randomised, parallel-group, double-blind, multi-centre study comparing carvedilol and placebo over a period of approximately 6 months in the above patient population. The primary end-point is the comparison of the mean change, from baseline to the final visit, in radionuclide-determined LV ejection fraction among patients on placebo with those on carvedilol stratified according to the presence of hibernating myocardium. Hibernating status will be determined by a combination of echocardiographic and myocardial perfusion (technetium-99m sestamibi) imaging. RESULTS: 255 patients have undergone screening tests of which 207 have been randomised so far. The study intends to randomise 400 patients and the first report of results is expected in 2000. CONCLUSIONS: As far as we are aware this is the first randomised controlled trial to investigate the effects of treatment in patients stratified according to the presence of hibernating myocardium. The study will provide insights into the prevalence of myocardial hibernation, its natural history, and its influence on prognosis as well as the interaction between the presence of hibernating myocardium and the effects of treatment with carvedilol.

Adrenergic beta-Antagonists↗
PubMed1999

Value of ambulatory intra-arterial blood pressure monitoring in the long-term prediction of left ventricular hypertrophy and carotid atherosclerosis in essential hypertension.

The aim of this study was to compare the abilities of clinic and ambulatory blood pressure (BP) to predict the long term occurrence of left ventricular hypertrophy and carotid atherosclerosis in uncomplicated hypertensive patients. Two hundred and ninety-five patients who had undergone 24-h ambulatory intra-arterial BP monitoring on the basis of an elevated clinic BP, attended follow-up at a mean of 10.2 (+/- 3.5) years later. This consisted of a history, physical examination, risk factor profile and serum cholesterol level. Echocardiography and carotid ultrasonography were also performed to determine left ventricular mass index and maximal intima-media thickness (IMTmax), a measure of carotid atherosclerosis severity. The factors most strongly correlated with both left ventricular mass index and IMTmax were age, 24-h mean pulse pressure and 24-h mean systolic BP. Age, 24-h mean systolic BP and body mass index were independent correlates of left ventricular hypertrophy (R2 = 17%), whereas age, 24-h mean pulse pressure and pack years were independent predictors of carotid atherosclerosis (R2 = 34%). Clinic BP did not feature in the final model for the long term prediction of cardiovascular end-organ damage. These findings promote a role for ambulatory BP monitoring in guiding aggressiveness of drug therapy in an attempt to limit potential target organ damage.

Adult↗
PubMed1999

Why cardiac magnetic resonance imaging will not make it.

Coronary artery disease is currently the largest killer in the western world, and is estimated to become the leading cause of death worldwide by the year 2020. The question therefore is whether magnetic resonance imaging currently has a place in the already extremely well equipped armamentarium of cardiac testing. Although it is promising, its clinical use is somewhat limited by high cost and low availability of equipment and trained personnel. The absence of portable systems for cardiac application make cardiac magnetic resonance imaging in the emergency room, at the patient's bedside or in the doctor's office impossible. The comparison of the cardiac magnetic resonance imaging with proven and cost-effective techniques like echocardiography and nuclear imaging will be decisive in terms of the choice of imaging modalities in cardiology.

Acute Disease↗
PubMed1999

The role of neurohormonal antagonists in hibernating myocardium.

Hibernating myocardium is characterized by chronic reduction of myocardial blood flow due to obstructive coronary artery disease, causing reversible left ventricular dysfunction and flow-metabolism mismatch. The condition is unstable and increasing demand may lead to further left ventricular dysfunction or necrosis causing death or worsening heart failure. Recognition of the condition is difficult and requires complex cardiac imaging protocols. Treatment protocols are also poorly defined. This review addresses both the diagnostic and therapeutic aspects of hibernating myocardium.

Chronic Disease↗
PubMed1999

Dobutamine echocardiography predicts functional outcome after revascularisation in patients with dysfunctional myocardium irrespective of the perfusion pattern on resting thallium-201 imaging.

OBJECTIVE: To evaluate whether the predictive value of dobutamine echocardiography for assessing contractile reserve was altered by differing patterns of regional myocardial perfusion. PATIENTS: 31 consecutive patients with symptomatic congestive heart failure (left ventricular ejection fraction < 35%) caused by coronary artery disease. SETTING: A district general hospital. METHODS: Thallium-201 perfusion imaging and low dose dobutamine (5-15 microg/kg/min) echocardiography were performed and resting echocardiography was repeated three months after revascularisation. Perfusion pattern and systolic wall thickening were compared using a 12 segment left ventricular model. RESULTS: Of the 273 severely dysfunctional segments, 106 (39%) showed a normal perfusion and 167 (61%) an abnormal pattern. After revascularisation, recovery occurred in 71 of the segments with a normal perfusion pattern, and in these a dobutamine response was observed in 61 (86%); recovery also occurred in 56 segments with a mild to moderate abnormality of perfusion, and in these a dobutamine response was seen in 46 (81%) (NS). After revascularisation, the positive and negative predictive values for recovery of dysfunctional segments, where the majority were abnormally perfused, were 88% and 86%, respectively. Systolic wall thickening score indices improved from (mean (SD)) 3.21 (0.58) to 2. 6 (0.66) (p < 0.001) after revascularisation in dobutamine responsive patients (n = 24) compared with patients who did not show a dobutamine response (2.86 (0.65) and 3.13 (0.56), p = 0.61, respectively). CONCLUSIONS: Dobutamine echocardiography predicted improvement of dysfunctional myocardium after revascularisation irrespective of the resting perfusion pattern seen.

Adult↗
PubMed1999

Biodistribution, radiation dosimetry and pharmacokinetics of 111In-antimyosin in idiopathic inflammatory myopathies.

UNLABELLED: In view of the established role of 111In-antimyosin in the detection of heart muscle pathology, radiation dose estimates were made for this substance. Biodistribution and biokinetic data were obtained from our studies, which failed to show abnormal uptake of 111In-antimyosin in localized sites of skeletal muscle involvement in patients with idiopathic inflammatory myopathies. METHODS: After intravenous administration of 74 MBq (2 mCi) 111In-antimyosin, gamma camera scintigraphy was performed in 12 adult patients with inflammatory muscle disease and in 2 control patients. Six whole-body scans were performed over 72 h, and uptake of 111In-antimyosin in organs was quantified using an attenuation-corrected conjugate counting method. Residence times in source organs were used with MIRDOSE software to obtain radiation dose estimates. Pharmacokinetic parameters were derived from serial whole-blood and plasma 111In concentrations. RESULTS: The tracer cleared slowly from the circulation, and highest organ uptakes were found in the marrow and liver; kidneys showed the highest concentrations. Uptake was also evident in spleen, the facial image and male genitalia. CONCLUSION: For a typical administered activity of 74 MBq 111In-antimyosin, the kidneys receive the highest dose (58 mSv), and the effective dose is 11 mSv. Radioactivity was cleared from plasma at an average rate of 136 mL/h, and the mean steady-state distribution was approximately 5 L plasma.

Adult↗
PubMed1998

Denaturation of supercoiled DNA: a Monte Carlo study.

A theoretical investigation of the denaturation characteristics of a supercoiled DNA has been presented employing a Metropolis Monte Carlo algorithm to examine the overall melting profiles of a supercoiled plasmid as the temperature is varied. We show that in contrast to a previously presented algorithm, this much simpler method is sufficient to explain almost all the overall denaturation characteristics and it also correctly calculates the detailed denaturation probabilities of each base pair at various degrees of supercoiling. We also present for the first time a theoretical investigation of the alkaline denaturation of a supercoiled plasmid. Although one can qualitatively reproduce the denaturation profiles using the present Monte Carlo algorithm, the agreement with experiment is not as good as in the case of thermal denaturation. The possible sources of discrepancy between theory and experiment have been discussed.

Algorithms↗
PubMed1998

Cardiovascular outcome in white-coat versus sustained mild hypertension: a 10-year follow-up study.

BACKGROUND: The aim of this study was to compare the risk conferred by white-coat versus sustained mild hypertension for the development of cardiovascular disease. METHODS AND RESULTS: Patients (n=479) who underwent 24-hour intra-arterial ambulatory blood pressure monitoring on the basis of a persistently elevated clinic systolic blood pressure of 140 to 180 mm Hg were followed up for the development of subsequent cardiovascular events during a 9.1+/-4. 2-year period. White-coat hypertension, defined as a clinic systolic blood pressure of 140 to 180 mm Hg associated with a 24-hour ambulatory systolic blood pressure <140 mm Hg and diastolic blood pressure <90 mm Hg, was present in 126 patients, and the remainder had sustained mild hypertension. A subgroup of patients without complications underwent follow-up echocardiography and carotid ultrasound. White-coat hypertensives were younger (44+/-12 versus 52+/-10 years, respectively; P<0.001) and had a significantly lower incidence of cardiovascular events (1.32 versus 2.56 events per 100 patient-years, respectively; P<0.001) than sustained hypertensives. Multivariate analysis revealed age (P=0.002), sex (P=0.007), race (P=0.001), smoking (P=0.005), and the presence of white-coat hypertension (hazard ratio, 0.29; 95% CI, 0.09 to 0.90; P=0.04) to be independent predictors of subsequent cardiovascular events. Subgroup analysis in patients without complications revealed a lower incidence of left ventricular hypertrophy and lesser degrees of carotid hypertrophy in the white-coat group. CONCLUSIONS: These findings indicate a relatively benign outcome in white-coat hypertension compared with sustained mild hypertension.

Adult↗
PubMed1998

Value of dobutamine stress echocardiography for the detection of multivessel coronary artery disease.

Dobutamine stress echocardiography has been shown to accurately detect coronary artery disease (CAD), but it is not clear whether it has the ability to detect multivessel CAD relative to clinical and exercise electrocardiography. Therefore, the aim of this study was to evaluate the ability of dobutamine stress echocardiography to identify multivessel CAD and ascertain its incremental value when combined with clinical and exercise test variables. One hundred twenty-one consecutive patients referred for coronary arteriography on the basis of symptoms and exercise electrocardiography underwent dobutamine stress echocardiography. Significant multivessel CAD was defined as the presence of > or =70% diameter stenosis in > or =2 major epicardial arteries. Stepwise logistic regression analysis was performed using the clinical exercise test and echocardiographic variables. The strongest independent variables predicting the presence of multivessel CAD were systolic wall thickening index at peak stress (p < 0.0001), presence of wall thickening abnormalities in multiple vascular territories (p = 0.001), and a history of acute myocardial infarction (p = 0.04). Furthermore, dobutamine echocardiography significantly enhanced the prediction of multivessel disease when combined with clinical and exercise test variables (p = 0.001). Dobutamine stress echocardiography adds independent and incremental information to clinical and exercise test variables for identifying multivessel CAD.

Adult↗
PubMed1998

Independent prognostic value of the extent and severity of systolic wall thickening abnormality at infarct site after thrombolytic therapy.

BACKGROUND: The prognostic value of systolic wall thickening abnormality after acute myocardial infarction in the thrombolytic era is not clearly known. METHODS AND RESULTS: Accordingly, 119 consecutive patients with acute myocardial infarction who underwent thrombolysis were investigated with exercise electrocardiography and rest echocardiography at predischarge evaluation and were followed up for cardiac events. During a mean follow-up period of 19 months, 43 patients had cardiac events. Multivariate analysis with clinical, exercise electrocardiographic, and rest echocardiographic parameters showed that the independent predictors of cardiac events were systolic wall thickening score at the site of infarct (p = 0.02), end-systolic volume (p = 0.03), and exercise time (p = 0.02). The only independent predictor for both recurrent ischemic (death, unstable angina, and reinfarction) and nonischemic events (congestive heart failure and ventricular tachycardia) was systolic wall thickening score at the site of infarct (p = 0.02 and p = 0.007, respectively). CONCLUSIONS: Systolic wall thickening abnormality at rest is an important independent predictor of cardiac events in patients who have undergone thrombolysis after acute myocardial infarction.

Echocardiography↗