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Biomedical subjects

A Lahiri

Publications and source records attributed to A Lahiri.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effect of revascularization on left ventricular remodeling in patients with heart failure from severe chronic ischemic left ventricular dysfunction.

Few data exist regarding the effect of revascularization on left ventricular (LV) geometry in patients with severe LV systolic dysfunction and viable myocardium. We hypothesized that patients with chronic ischemic LV dysfunction but viable myocardium will have improved LV geometry after revascularization, which in turn will improve long-term outcome. Accordingly, 70 patients with severe ischemic LV dysfunction (LV ejection fraction <0.35) were studied at rest. They then either underwent revascularization (n = 36) or were treated medically (n = 34). Fifty-four patients had viable myocardium, and 16 did not. They were evaluated for change in LV function and geometry (size and shape) a mean of 21 months later. Further follow-up was performed for a mean of 3.5 years to determine outcome. Patients with viable myocardium had improvement not only in regional and global function, but also in LV geometry (shape and size), which was independent of and incremental to the improvement in function. On long-term follow-up, change in LV end-systolic volume was the only multivariate discriminator between 15 patients who died and 55 who did not, irrespective of whether they had undergone revascularization. Thus, measurement of the effect of revascularization of viable myocardium in chronic ischemic heart disease should not only include improvement in resting regional and global LV function, but also LV geometry. Improvement in LV geometry contributes to better LV systolic function, which in turn is the best predictor of survival after revascularization.

Cohort Studies↗
PubMed2001

Effect of aging on the prognostic significance of ambulatory systolic, diastolic, and pulse pressure in essential hypertension.

BACKGROUND: This study compared the relative prognostic significance of 24 hour intra-arterial ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and pulse pressure (PP) parameters in middle-aged versus elderly hypertensives. METHODS AND RESULTS: A total of 546 subjects aged <60 years and 142 subjects aged >/=60 years who had undergone baseline pretreatment 24-hour intra-arterial ambulatory blood pressure monitoring were followed for 9.2+/-4.1 years. Multivariate analysis showed that in younger subjects, 24-hour, daytime, and nighttime DBP, MAP, and SBP, when considered individually, were positively related to morbid events; DBP parameters provided the best predictive values. In the group >/=60 years (elderly group), 24-hour, daytime, and nighttime PP and SBP were the most predictive parameters, whereas ambulatory DBP and MAP measurements failed to provide any prognostic value. When 24-hour values of SBP and DBP were jointly included in the baseline model, DBP (z=2.02, P=0.04) but not SBP (z=-0.43, P=0.67) was related to outcome in younger subjects, whereas in the elderly group, SBP (z=3.33, P=0.001) was positively and DBP (z=-1.75, P=0.07) was negatively related to outcome. Clinic blood pressure measurements failed to provide any independent prognostic value in either age group. CONCLUSIONS: The relative prognostic significance of ambulatory blood pressure components depends on age; DBP parameters provided the best prognostic value in middle-aged individuals, whereas PP parameters were the most predictive in the elderly. This may reflect differing underlying hemodynamic mechanisms of hypertension in these age groups.

Adult↗
PubMed2001

Enhanced detection of reversible perfusion defects by Tc-99m sestamibi compared to Tc-99m tetrofosmin during vasodilator stress SPECT imaging in mild-to-moderate coronary artery disease.

OBJECTIVES: We prospectively compared dipyridamole single-photon emission computed tomography (SPECT) imaging with Tc-99m sestamibi and Tc-99m tetrofosmin for the detection of reversible perfusion defects in patients with mild-to-moderate coronary artery disease. BACKGROUND: Tc-99m tetrofosmin has a lower first-pass myocardial extraction fraction compared to Tc-99m sestamibi and thus could underestimate mild perfusion defects. METHODS: Eighty-one patients with 50% to 90% stenosis in one or two major epicardial vessels without previous myocardial infarction, and seven with <5% probability of coronary artery disease underwent dipyridamole SPECT imaging with both agents. The SPECT data were analyzed quantitatively. RESULTS: Tc-99m sestamibi detected reversible perfusion defects in a greater number of segments (total 363 and 285, p < 0.001, and mean +/- SD, 2.2 +/- 3.0 and 1.8 +/- 2.5 per patient, p = 0.008, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively), demonstrated a larger extent of perfusion defect (mean +/- SD, 15.8% +/- 12.3% and 12.0% +/- 11.4%, p < 0.03, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively) and more often correctly identified patients with disease in more than one coronary artery (p = 0.02). There was better defect contrast with Tc-99m sestamibi (defect/normal wall count ratios were 0.60 +/- 0.15 vs. 0.73 +/- 0.14 for Tc-99m sestamibi and Tc99m tetrofosmin, respectively, p = 0.01, for reversible defects seen in identical segments with both agents; and 0.73 +/- 0.16 vs 0.79 +/- 0.17, respectively, p <0.01, for reversible defects detected with either agent alone). There was no significant difference in diagnostic sensitivity or image quality. CONCLUSIONS: These differences between two commonly used tracers may have significant diagnostic and prognostic implications.

Adult↗
PubMed2001

Intravenous myocardial contrast echocardiography predicts recovery of dysynergic myocardium early after acute myocardial infarction.

OBJECTIVES: We aimed to ascertain whether triggered intravenous myocardial contrast echocardiography (MCE) can predict functional recovery in patients with acute myocardial infarction (AMI) and to determine the optimal triggering interval in this setting. BACKGROUND: Detection of myocardial viability early after AMI has both therapeutic and prognostic implications. Myocardial contrast echocardiography using intracoronary injections of contrast can detect viable myocardium, but there is little data on the use of recently developed intravenous MCE techniques for this purpose. METHODS: Ninety-six patients with recent AMI (4.8 +/- 1.7 days) underwent echocardiography at baseline and six months later or three months after revascularization to determine regional function (score 1 = normal to 3 = akinetic). Myocardial contrast echocardiography was performed at baseline using intravenous injections of Optison. Triggering intervals of 1:1 (early) and 1:10 (delayed) cardiac cycles were used. Segments were deemed viable if they demonstrated homogeneous contrast opacification. RESULTS: Of 400 akinetic segments at baseline, 109 (27%) improved during the follow-up period, and 375 (94%) were adequately visualized with MCE, of which 59 (16%) were homogeneously opacified by early and 125 (33%) by delayed MCE (negative predictive value for recovery of contractile function 74% and 84%, positive predictive value 29% and 47%, respectively). Independent predictors of functional recovery were delayed MCE (odds ratio [OR]: 4.0, p < 0.001), revascularization (OR: 6.0, p < 0.001), and log creatine kinase (OR: 0.5, p = 0.03). However, the presence or absence of >90% stenosis of the infarct-related artery did not influence the ability of triggered MCE to predict functional recovery. CONCLUSIONS: Intravenous delayed triggered MCE can independently detect myocardial viability early after AMI.

Aged↗
PubMed2001

Experience with difficult keloids.

A large number of treatment modalities have been used to treat keloid scars, with varying degrees of success. A modified combination therapy consisting of cryotherapy and intralesional triamcinolone injection has given good results in 43 patients, with complete resolution in 28% and significant improvement in 44%. We find it particularly useful for treating recurrent and/or difficult keloids.

Adolescent↗
PubMed2001

Regression of left ventricular remodeling in chronic heart failure: Comparative and combined effects of captopril and carvedilol.

BACKGROUND: This study evaluated the independent and combined effects of captopril and carvedilol on left ventricular remodeling in chronic heart failure. Although angiotensin-converting enzyme inhibitors and b-blockers are known to attenuate the remodeling process in chronic heart failure, a direct comparison of these agents has not been performed. METHODS: We investigated 57 patients with mild to moderate chronic heart failure (48 ischemic, 9 nonischemic) who were randomized in a double-blind fashion to treatment with carvedilol or captopril at maximum doses of 25 mg twice daily for 3 months, followed by 3 months of combined treatment. Serial echocardiography, right heart catheterization, and treadmill exercise testing were performed at baseline, 3 months, and 6 months. After exclusions, 49 patients were evaluated during monotherapy and 48 during combination therapy. RESULTS: Carvedilol monotherapy produced significant reductions in end-systolic volume, leading to a greater median increase in ejection fraction compared with captopril monotherapy (4.7% vs 1.5%, respectively; P <.05). Each drug caused similar reductions in left ventricular mass, chamber sphericity, and pulmonary artery wedge pressure during monotherapy and combined treatment. Adjunctive treatment with carvedilol produced a trend toward a greater increase in ejection fraction (4.3% vs 2.7%, respectively; P not significant) and significantly greater reductions in the wall thickening score index than with captopril (0.25 vs 0.08, respectively; P =.04). CONCLUSIONS: Although angiotensin-converting enzyme inhibitor therapy did not alter left ventricular volume, treatment with carvedilol was associated with reductions in chamber volume; both drugs reduced left ventricular mass and sphericity. These beneficial effects on remodeling may help to explain the relative prognostic benefits of these therapies.

Adrenergic beta-Antagonists↗
PubMed2001

Role of dobutamine echocardiography in detection of myocardial viability for predicting outcome after revascularization in ischemic cardiomyopathy.

Coronary artery disease is the most common cause of heart failure in the Western world. Compared with medical therapy, surgical revascularization has been shown to improve survival rates in nonrandomized trials in patients with ischemic cardiomyopathy. However, perioperative mortality is high in this group of patients who do not demonstrate significant viable myocardium. Echocardiography during dobutamine infusion has been shown to reliably detect viable myocardium. Several studies have demonstrated its ability to provide high predictive value for recovery of both regional and global left ventricular function after revascularization. Indeed, nonrandomized studies also have indicated its value in predicting which patients with severe ischemic cardiomyopathy are likely to survive after revascularization. Dobutamine stress echocardiography has emerged as a safe and valuable technique for the assessment of myocardial viability and for the selection of patients for revascularization.

Cardiotonic Agents↗
PubMed2001

A randomized, double-blind comparison of the efficacy and tolerability of once-daily modified-release diltiazem capsules with once-daily amlodipine tablets in patients with stable angina.

A randomized, double-blind, parallel-group study comparing the efficacy and tolerability of once-daily diltiazem capsules with amlodipine tablets in patients with stable angina. After a run-in period of 1 to 3 weeks, 34 patients received once-daily diltiazem and 33 patients received amlodipine. Patients received either diltiazem, 240 mg/day, or amlodipine, 5 mg/day, for 2 weeks followed by diltiazem, 360 mg/day, or amlodipine, 10 mg/day, for 2 weeks. Standard treadmill exercise testing was the primary efficacy assessment. Patients also recorded incidence of angina attacks and use of glyceryl trinitrate spray. Both treatments gave significant improvement in time to onset of angina and time to maximal exercise. With the exception of amlodipine, 5 mg/day, both treatments gave significant increases in time to 1-mm ST segment depression. Diltiazem, 360 mg/day, gave a significant decrease in rate pressure product. There were no significant treatment differences in any of the exercise test parameters. Both treatments reduced incidence of angina attacks and use of glyceryl trinitrate spray. The incidence of edema was significantly less in patients receiving diltiazem. In conclusion, both treatments were effective in controlling patients' angina, but diltiazem was better tolerated, with a lower incidence of edema.

Adult↗
PubMed2001

A prospective comparison of echocardiographic wall motion score index and radionuclide ejection fraction in predicting outcome following acute myocardial infarction.

OBJECTIVE: To characterise echocardiographic wall motion score index (WMSI) as a surrogate measure of left ventricular ejection fraction (EF) following acute myocardial infarction (AMI) and to compare its prognostic value with that of EF measured by radionuclide ventriculography (RNV). DESIGN: A prospective study to compare baseline echocardiographic WMSI with RNV EF in consecutive patients thrombolysed for AMI, both performed on the same day before discharge, and their relative prognostic values in predicting cardiac events. SETTING: District general hospital coronary care unit and cardiology department. PATIENTS: 120 consecutive patients free of exclusion criteria thrombolysed for AMI and followed up for a mean (SD) of 13 (10) months. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Correlation coefficients and receiver operating characteristic curve analyses plus cardiac event rates at follow up between RNV EF and echocardiographic WMSI. RESULTS: WMSI correlated well with RNV EF. The best corresponding WMSIs for EFs 45%, 40%, and 35% were 0.6, 0.8, and 1.1, respectively. There were 42 cardiac events during follow up. Although both RNV EF and WMSI were strong univariate predictors of cardiac events, only WMSI independently predicted outcome in a multivariate model. All three WMSI cut offs significantly predicted events, while an RNV EF cut off of </= 45% v > 45% failed to reach significance. CONCLUSIONS: Although both RNV and echocardiographic WMSI strongly predicted cardiac outcome, WMSI, a cheaper and more readily available technique, is more discriminatory, especially in cases of mild left ventricular dysfunction following AMI.

Adult↗
PubMed2001

Humoral immune responses in different clinical forms of tuberculosis.

To assess the antibody responses in different clinical forms of tuberculosis in an attempt to ascertain the specificity of such a response, so that it may be used as a diagnostic tool, 93 tuberculosis cases and 62 normal healthy controls were included in the study. All the cases were diagnosed as tuberculosis by clinical picture including radiological findings, blood picture, fine needle aspiration cytology (FNAC) or histopathological features, sputum examination or urine culture for acid-fast bacilli. IgM and IgG antibodies in the cases and controls were detected by ELISA using A60 antigen from M. bovis and compared with common diagnostic parameters of tuberculosis like presence of acid-fast bacilli in smear and tuberculin response. Antibody responses with A60 antigen has not been found to be specific and often failed to detect a new case.

Adolescent↗
PubMed2000

Discrete breathers: exact solutions in piecewise linear models

Exact breather solutions are constructed in piecewise linear (PWL) versions of the discrete nonlinear Schrodinger and Klein-Gordon equations. These solutions correspond to intersections of stable and unstable manifolds of relevant fixed points in associated 2D mappings, an exact construction of which is possible due to the PWL nature of the models. Such exact solutions give us insight into several aspects of breather properties. The problem of dynamical stability of the breathers is mentioned as an instance, detailed results on which will be presented in a future paper.

Journal Article↗
PubMed2000

Molecular dynamics of the anticodon domain of yeast tRNA(Phe): codon-anticodon interaction.

We have studied the effect of codon-anticodon interaction on the structure and dynamics of transfer RNAs using molecular dynamics simulations over a nanosecond time scale. From our molecular dynamical investigations of the solvated anticodon domain of yeast tRNA(Phe) in the presence and absence of the codon trinucleotides UUC and UUU, we find that, although at a gross level the structures are quite similar for the free and the bound domains, there are small but distinct differences in certain parts of the molecule, notably near the Y37 base. Comparison of the dynamics in terms of interatomic or inter-residual distance fluctuation for the free and the bound domains showed regions of enhanced rigidity in the loop region in the presence of codons. Because fluorescence experiments suggested the existence of multiple conformers of the anticodon domain, which interconvert on a much larger time scale than our simulations, we probed the conformational space using five independent trajectories of 500 ps duration. A generalized ergodic measure analysis of the trajectories revealed that at least for this time scale, all the trajectories populated separate parts of the conformational space, indicating a need for even longer simulations or enhanced sampling of the conformational space to give an unequivocal answer to this question.

Anticodon↗
PubMed2000

Comparison of left ventricular ejection fraction and volumes in heart failure by echocardiography, radionuclide ventriculography and cardiovascular magnetic resonance; are they interchangeable?

AIMS: To prospectively compare the agreement of left ventricular volumes and ejection fraction by M-mode echocardiography (echo), 2D echo, radionuclide ventriculography and cardiovascular magnetic resonance performed in patients with chronic stable heart failure. It is important to know whether the results of each technique are interchangable, and thereby how the results of large studies in heart failure utilizing one technique can be applied using another. Some studies have compared cardiovascular magnetic resonance with echo or radionuclude ventriculography but few contain patients with heart failure and none have compared these techniques with the current fast breath-hold acquisition cardiovascular magnetic resonance. METHODS AND RESULTS: Fifty two patients with chronic stable heart failure taking part in the CHRISTMAS Study, underwent M-mode echo, 2D echo, radionuclude ventriculography and cardiovascular magnetic resonance within 4 weeks. The scans were analysed independently in blinded fashion by a single investigator at three core laboratories. Of the echocardiograms, 86% had sufficient image quality to obtain left ventricular ejection fraction by M-mode method, but only 69% by 2D Simpson's biplane analysis. All 52 patients tolerated the radionuclude ventriculography and cardiovascular magnetic resonance, and all these scans were analysable. The mean left ventricular ejection fraction by M-mode cube method was 39+/-16% and 29+/-15% by Teichholz M-mode method. The mean left ventricular ejection fraction by 2D echo Simpson's biplane was 31+/-10%, by radionuclude ventriculography was 24+/-9% and by cardiovascular magnetic resonance was 30+/-11. All the mean left ventricular ejection fractions by each technique were significantly different from all other techniques (P<0.001), except for cardiovascular magnetic resonance ejection fraction and 2D echo ejection fraction by Simpson's rule (P=0.23). The Bland-Altman limits of agreement encompassing four standard deviations was widest for both cardiovascular magnetic resonance vs cube M-mode echo and cardiovascular magnetic resonance vs Teichholz M-mode echo at 66% each, and was 58% for radionuclude ventriculography vs cube M-mode echo, 44% for cardiovascular magnetic resonance vs Simpson's 2D echo, 39% for radionuclide ventriculography vs Simpson's 2D echo, and smallest at 31% for cardiovascular magnetic resonance-radionuclide ventriculography. Similarly, the end-diastolic volume and end-systolic volume by 2D echo and cardiovascular magnetic resonance revealed wide limits of agreement (52 ml to 216 ml and 11 ml to 188 ml, respectively). CONCLUSION: These results suggest that ejection fraction measurements by various techniques are not interchangeable. The conclusions and recommendations of research studies in heart failure should therefore be interpreted in the context of locally available techniques. In addition, there are very wide variances in volumes and ejection fraction between techniques, which are most marked in comparisons using echocardiography. This suggests that cardiovascular magnetic resonance is the preferred technique for volume and ejection fraction estimation in heart failure patients, because of its 3D approach for non-symmetric ventricles and superior image quality.

Echocardiography↗
PubMed2000

Power doppler harmonic imaging: a feasibility study of a new technique for the assessment of myocardial perfusion.

BACKGROUND: The aim of the study was to assess the feasibility of a new technique, power Doppler harmonic imaging (PDHI), for assessing myocardial perfusion through a venous injection of microbubbles, with the use of a new ultrasound contrast agent. METHODS AND RESULTS: Fifteen patients with known coronary artery disease and a resting perfusion abnormality on Tc-99m sestamibi single-photon emission computed tomography (SPECT) underwent PDHI at rest during intravenous injections of 2 to 3 mL of Sonovue (Bracco SpA, Milan, Italy), a new second-generation ultrasound contrast agent. Myocardial perfusion was determined to be present or absent by use of a 5-segment model by 2 blinded observers for both PDHI and SPECT. Of a total of 75 possible myocardial segments, 7 (9%) were not analyzed because of obvious artifacts on PDHI. SPECT showed perfusion defects in 40 of the remaining 68 segments, whereas PDHI showed 39 defects. There was high concordance between the 2 imaging modalities for the presence (93%) as well as the location (96% for the anteroseptal region, 93% for the inferoposterior region, and 87% for the apical region) of the defects. CONCLUSIONS: These preliminary results suggest that PDHI is a feasible technique for the detection of resting myocardial perfusion defects in patients with coronary artery disease after a venous injection of a new second-generation ultrasound contrast agent.

Adult↗
PubMed2000

Improved efficacy and safety of controlled-release diltiazem compared to nifedipine may be related to its negative chronotropic effect.

The objective of this study was to assess the safety and efficacy of long-acting preparations of two commonly used calcium antagonists with particular reference to their effects on heart rate. Twenty patients with chronic stable angina were recruited to a double-blind, double-dummy crossover study of controlled-release diltiazem (diltiazem CR) versus sustained-release nifedipine (nifedipine SR) and underwent clinical assessment, symptom and adverse event reporting, and repeated treadmill exercise tests over a 10- to 11-week period. The main outcome measures were heart rate at rest and exercise, incidence of angina and nitroglycerin use, treadmill exercise performance (duration, time to angina, time to 1-mm ST-segment depression, heart rate at equivalent maximal exercise, and maximal ST-segment depression), and adverse events. Diltiazem CR significantly reduced heart rate at rest and equivalent exercise and incidence of angina and nitroglycerin use compared with nifedipine SR. Exercise duration time to angina and time to 1-mm ST-segment depression (but not maximal ST-segment depression) were all significantly improved by diltiazem CR. Diltiazem CR also caused significantly fewer adverse events than nifedipine SR. Calcium antagonists with negative chronotropic effects (eg, diltiazem CR) are safer and more efficacious as monotherapy in chronic stable angina than dihydropyridines (eg, nifedipine SR) even when a long-acting formulation of the latter is used.

Adult↗
PubMed2000

Racial variation in cardiovascular morbidity and mortality in essential hypertension.

OBJECTIVES: To perform a longitudinal comparison of morbidity and mortality among white, south Asian and Afro-Caribbean hypertensive patients in relation to baseline demographic characteristics and clinic and ambulatory blood pressure variables. DESIGN: Observational follow up study. SETTING: District general hospital and community setting in Harrow, England. PATIENTS: 528 white, 106 south Asian, and 54 Afro-Caribbean subjects with essential hypertension who had undergone 24 hour ambulatory intra-arterial blood pressure monitoring. INTERVENTIONS: Follow up for assessment of all cause morbidity and mortality over a mean (SD) of 9.2 (4.1) years. MAIN OUTCOME MEASURES: Non-cardiovascular death, coronary death, cerebrovascular death, peripheral vascular death, non-fatal myocardial infarction, non-fatal stroke, coronary revascularisation. RESULTS: South Asians had the highest all cause event rate of 3.46, compared with 2.50 (NS) and 0.90 (p = 0.002) events/100 patient-years for whites and Afro-Caribbeans, respectively. This was because of an excess of coronary events (2.86 v 1.32 events/100 patient-years in south Asians v whites, respectively; p = 0.002). Age (p < 0.001), sex (p < 0.001), race (south Asians : whites, hazard ratio 1.79; p = 0.008), diabetes (p = 0.05), previous history of cardiovascular disease (p < 0.001), and 24 hour ambulatory systolic blood pressure (p = 0.006) were independent predictors of time to a first event. Clinic blood pressure did not provide additional prognostic information. CONCLUSIONS: South Asian origin was an independent predictor of all cause events, mainly because of an excess of coronary events in this group. Ambulatory but not clinic blood pressure was of additional value in predicting subsequent morbidity and mortality.

Adult↗