Search PubMed⌕ Search

Biomedical subjects

A Lahiri

Publications and source records attributed to A Lahiri.

At least 73 records · Page 4Linked to original sources
PubMed1998

Influence of background correction in the estimation of myocardial uptake of 99mTc labelled perfusion imaging agents.

The effects of different corrections for background activity in the estimation of low organ uptake of radiopharmaceuticals have been examined using myocardial perfusion imaging agents. Estimates of myocardial uptake of 99mTc-labelled MIBI and tetrofosmin were made both at rest and after exercise. Patients were given one or other of the agents (12 MIBI; 17 tetrofosmin) and the measurements at rest and after exercise were made within a week of each other using a planar gamma camera method incorporating an attenuation-corrected, geometric mean technique. Myocardial uptakes were estimated using two different background corrections and also with no background subtraction. Mean values were in the range 1.3 to 3.0% and showed that, for both agents, uptakes estimated with and without background correction could differ by a factor of two. Although the study was not designed to compare myocardial uptakes of the two agents, a background correction which accounted separately for activity in tissue over- and under-lying the heart resulted in similar mean values for tetrofosmin (1.7% both at rest and after exercise) and for MIBI (1.8% rest; 1.9% exercise). For both agents, no significant difference was observed between myocardial uptakes at rest and after exercise measured at about two hours post-injection.

Adult↗
PubMed1998

Safety, tolerability, and antiischaemic efficacy of ITF-296, a nitric oxide donor, in patients with chronic stable angina.

A double-blind, placebo-controlled, parallel-group, dose-escalation study was performed to evaluate ITF-296, a new nitric oxide donor, in chronic stable angina. Twenty-four male patients underwent exercise electrocardiography in conjunction with echocardiography on three separate occasions within 2 weeks. After two reproducibility tests, the third exercise test was immediately preceded by a 30-min intravenous infusion of either placebo or 0.3, 1.0, or 3.0 microg/kg/min of ITF-296, with six patients in each treatment group. During ITF-296 infusion, systolic blood pressure decreased by a mean of 12 mm Hg compared with a 2 mm Hg increase in the placebo group [difference, -14; 95% confidence interval (CI), -23 to -6 mm Hg]. ITF-296 administration was followed by consistent increases in total exercise time, time to angina threshold, and time to 1-mm ST-segment depression. The mean change in total exercise time was 39 s on placebo and 94 s on ITF-296 (mean difference, 54 s; 95% CI, -48 to 157 mm Hg). The 1.0- and 3.0-microg/kg/min doses increased exercise time by >2 min with no important change in peak rate-pressure product compared with baseline. The trends exhibited in this small preliminary study were consistently pharmacologically plausible and indicate that ITF-296 shows potential antiischaemic efficacy in patients with chronic stable angina.

Aged↗
PubMed1998

Assessment of myocardial perfusion and contractile function by inotropic stress Tc-99m sestamibi SPECT imaging and echocardiography for optimal detection of multivessel coronary artery disease.

OBJECTIVE: To assess whether inotropic stress myocardial perfusion imaging, echocardiography, or a combination of the two could enhance the detection of multivessel disease, over and above clinical and exercise electrocardiographic data. DESIGN: 100 consecutive patients investigated by exercise electrocardiography and diagnostic coronary arteriography underwent simultaneous inotropic stress Tc-99m sestamibi SPECT (MIBI) imaging and echocardiography. MIBI imaging and echocardiographic data were analysed using a 12 segment left ventricular model, and each segment was ascribed to a particular coronary artery territory. The presence of perfusion defects with MIBI imaging or of wall thickening abnormality with echocardiography in at least two coronary artery territories at peak stress was taken as diagnostic of multivessel disease. Arteriographic evidence of > or = 50% stenosis was considered significant. RESULTS: 56 patients had multivessel disease. The sensitivity of the combination of MIBI imaging and echocardiography for detecting this was greater than either MIBI imaging or echocardiography alone (82%, 68%, and 68%, respectively; p = 0.005). Clinical and exercise electrocardiographic variables gave an R2 value of 18.2% for predicting multivessel disease. The addition of either MIBI imaging (R2 = 29.2%; p = 0.002) or echocardiography (R2 = 28.8%; p < 0.001) enhanced the detection of multivessel disease, and the inclusion of both had further incremental value (R2 = 34.8%; p = 0.003). Age (p = 0.03), MIBI imaging (p = 0.007), and echocardiography (p = 0.001) were independent predictors of multivessel disease. CONCLUSIONS: The assessment of both myocardial perfusion and contractile function by simultaneous inotropic stress MIBI imaging and echocardiography optimises the non-invasive detection of multivessel disease.

Cardiotonic Agents↗
PubMed1998

Carriage rate of group B streptococci in pregnant women and evaluation of different isolation media.

A study was conducted in 507 pregnant women of different parities, trimesters of pregnancy and age groups for finding out the colonisation rate of group B streptococci either in throat or vagina or from both sites. Incidence of carriage rate in throat was 4.73%, in vagina 9.66% and in both sites 12.03%. Age, parity, gestational period of women were not found to have any significant influence on the colonisation rate at different sites. Isolation rate of the organism was greatly enhanced using two selective media for isolation compared to using single selective medium or combination of non-selective media and a single selective medium.

Adult↗
PubMed1997

Superiority of nitrate-enhanced 201Tl over conventional redistribution 201Tl imaging for prognostic evaluation after myocardial infarction and thrombolysis.

BACKGROUND: 201Tl imaging has been widely used for postinfarction risk stratification. However, thrombolytic therapy and aspirin have significantly changed outcome, and there are few nuclear imaging studies that assess prognosis in such patients. Furthermore, newer techniques of 201Tl imaging, such as reinjection and nitrate-enhanced rest 201Tl imaging, have been shown to improve the detection of viable but jeopardized myocardium. METHODS AND RESULTS: We studied 100 consecutive patients, who remained event free 6 weeks after myocardial infarction and thrombolysis. Patients underwent conventional exercise and 4-hour redistribution imaging, followed on a separate day by nitrate-enhanced rest 201Tl study. Planar images were reported semiquantitatively by two experienced observers blinded to clinical data. Redistribution and rest injection images were classified as demonstrating reversible ischemia if they showed improvement in uptake by at least two grades in at least two segments in comparison with the initial exercise scintigram. Patients were followed up for 8 to 32 months (mean, 21 months); during this period, 37 patients had first cardiac events. Reversible ischemia was present in 29 patients on redistribution, of whom 14 (48%) had events; of 71 without reversible defects, 23 (32%) had events (hazard ratio, 1.5; 95% CI, 0.8 to 3.0; P=NS). Nitrate-enhanced rest 201Tl imaging detected reversible defects in 68 patients, of whom 33 (49%) had events, whereas of 32 without reversible defects, only 4 (13%) had subsequent cardiac events (hazard ratio, 8.1; 95% CI, 2.7 to 23.8; P<.001). CONCLUSIONS: Thus, after myocardial infarction and thrombolysis, even "stable" patients have a high (68%) incidence of viable but jeopardized myocardium, causing a high event rate. Those identified to be at high risk by perfusion imaging may benefit from early intervention.

Adult↗
PubMed1997

Detection of coronary artery disease with myocardial contrast echocardiography: comparison with 99mTc-sestamibi single-photon emission computed tomography.

BACKGROUND: The purpose of this study was to determine whether myocardial contrast echocardiography (MCE) can be used to detect coronary artery disease (CAD) during rest and pharmacological stress in humans through the use of venous injections of contrast. METHODS AND RESULTS: Thirty patients with known or suspected CAD underwent MCE and 99mTc-sestamibi single-photon emission computed tomography (SPECT) at baseline and after dipyridamole (0.56 mg x kg(-1)) infusion. Ten myocardial segments (5 each in the apical two- and four-chamber views) from the two sets of images using both methods were scored for myocardial perfusion as follows: 1=normal, 0.5=mildly reduced, and 0=severely reduced. The information from baseline and postdipyridamole images was then used to determine whether an abnormal segment was irreversible (similar abnormal perfusion at baseline and after dipyridamole) or reversible (perfusion better at baseline compared with after dipyridamole). Concordance between segmental scores was 92% (kappa=.99) for both methods. Concordance between normal perfusion and reversible or irreversible segmental defects was 90% (kappa=.80). Agreem between the two methods for each of the three vascular territories in each patient was 90% (kappa=.77), while agreement for the presence or absence of CAD in each patient was 86% (kappa=.86). In the 4 patients with disagreement, the perfusion scores were 0.5 for SPECT and 1.0 for MCE. CONCLUSIONS: This study shows that MCE, with venous injection of contrast, can define the presence of CAD during rest and pharmacological stress. The location of perfusion abnormalities and their physiologic relevance (reversible or irreversible) by MCE is similar to that provided by SPECT. MCE, therefore, holds promise for the noninvasive assessment of myocardial perfusion in humans.

Adult↗
PubMed1997

Beneficial effects of intravenous and oral carvedilol treatment in acute myocardial infarction. A placebo-controlled, randomized trial.

BACKGROUND: Evidence of efficacy and safety of beta-blockers after thrombolysis for acute myocardial infarction (AMI) is equivocal. Newer beta-blockers such as carvedilol have not been tested in this setting. METHODS AND RESULTS: This study investigated the effects of acute (intravenous) and long-term (6 months, oral) treatment with carvedilol versus placebo in 151 consecutive patients with AMI. Exercise ECG, ambulatory monitoring, and two-dimensional echocardiography were performed before hospital discharge and at 3 and 6 months. All patients were followed up and cardiovascular events recorded. The Cox proportional hazards model was used to compare time from randomization with the occurrence of a cardiovascular event, and Kaplan-Meier survival curves were calculated. Carvedilol was found to be safe, and it significantly reduced cardiac events compared with placebo (18 on carvedilol and 31 on placebo, P < .02). Fifty-four patients had heart failure at study entry; 34 received carvedilol. There were no adverse effects of carvedilol therapy and no excess events in this subgroup. Carvedilol produced significant reductions in heart rate (P < .0001), blood pressure (P < .005) at rest, and rate-pressure product at peak exercise (P < .003), but exercise capacity was unchanged. Left ventricular ejection fraction was not altered significantly by carvedilol, but stroke volume was higher at pre-hospital discharge examination (63 versus 53 mL; P < .01). Diastolic filling of the left ventricle (E/A ratio) was also improved (1.2 versus 0.9; P < .001). In a subgroup with left ventricular ejection fraction < 45% (n = 49 patients; 24 on carvedilol and 25 on placebo), carvedilol showed attenuation of remodeling. CONCLUSIONS: Carvedilol was well tolerated and safe to use in patients immediately after AMI, including those with heart failure, and significantly improved outcome.

Administration, Oral↗
PubMed1997

Prognostic value of dobutamine stress echocardiography in patients undergoing diagnostic coronary arteriography.

There are only a few studies addressing the prognostic value of dobutamine stress echocardiography in patients with suspected coronary artery disease and none have assessed its value compared with coronary arteriography. Accordingly, graded dobutamine stress echocardiography was performed in 121 patients who underwent coronary arteriography based on symptoms and the findings of treadmill exercise electrocardiography. During the follow-up period of mean (SD) months (15 +/- 9) there were 41 cardiac events (death [n = 5], acute myocardial infarction [n = 2], unstable angina [n = 29], and congestive heart failure [n = 5]). There were a greater number of patients with inducible wall motion abnormality (88%) on dobutamine stress with cardiac events compared with those without (55%, p <0.001). The wall motion score indexes at rest (1.6 +/- 0.6) and at peak stress (2.1 +/- 0.8) were worse in patients with cardiac events compared with those without (1.2 +/- 0.3, p <0.001 and 1.5 +/- 0.6, p <0.001, respectively). When multivariate analysis was performed using clinical, exercise, echocardiographic, and coronary arteriographic data the independent predictors of cardiac events were exercise duration (p = 0.01), presence of inducible wall motion abnormality (p = 0.03), and wall motion score index at peak stress (p <0.001). Thus, dobutamine stress echocardiography is a powerful predictor of future cardiac events in patients undergoing exercise testing and coronary arteriography for evaluation of chest pain and is superior to both exercise electrocardiography and coronary arteriography for the prediction of subsequent cardiac events.

Adult↗
PubMed1997

Longitudinal association of ambulatory pulse pressure with left ventricular mass and vascular hypertrophy in essential hypertension.

OBJECTIVE: To determine the longitudinal relationship between clinic and ambulatory blood pressures and subsequent left ventricular and carotid artery structure. DESIGN: A retrospective follow-up study. SETTING: A large district general hospital in Harrow, UK. PATIENTS: One hundred and forty patients who had been subjected to 24 h ambulatory intra-arterial blood pressure monitoring on the basis of their having an elevated clinic blood pressure were followed up randomly a mean of 9.4 +/- 3.4 years later. The ambulatory blood pressure parameters measured were the mean systolic, mean diastolic and mean pulse pressures. Follow-up variables assessed included the clinic blood pressure, body mass index, total cholesterol, number of years of follow-up, left ventricular mass index, carotid intima-media thickness and carotid artery cross-sectional area. MAIN OUTCOME MEASURES: The left ventricular mass index, carotid intima-media thickness and carotid artery cross-sectional area. RESULTS: The mean pulse pressure and mean systolic blood pressure were correlated significantly with the left ventricular mass index (r = 0.46, P < 0.001 and r = 0.36, P < 0.001, respectively), carotid intima-media thickness (r = 0.45, P < 0.001 and r = 0.37, P < 0.001, respectively) and carotid artery cross-sectional area (r = 0.46, P < 0.001 and r = 0.41, P < 0.001, respectively). The mean pulse pressure was associated independently with all three outcome measures. In addition, the body mass index was an independent determinant of the left ventricular mass index, whereas the serum cholesterol level was associated independently with the carotid artery cross-sectional area; the number of years of follow-up was related independently to the left ventricular mass index and carotid intima-media thickness, but not to the cross-sectional area. CONCLUSIONS: These findings suggest that ambulatory blood pressure monitoring can play a role in guiding the choice of doses in drug therapy to limit potential target organ damage.

Aged↗
PubMed1997

Hemodynamic and autonomic effects of intravenous saterinone in patients with chronic heart failure.

In this study, the hemodynamic and neurohumoral/autonomic effects of intravenous saterinone (a selective phosphodiesterase type III inhibitor, with additional alpha 1-blocking properties) were evaluated. In a double-blind, placebo-controlled design, 36 patients with moderate to severe heart failure were studied (saterinone, n = 24; placebo, n = 12). Invasive hemodynamic measurements, by using right-heart catheterization, were performed, as well as measurement of plasma neurohormones and analysis of heart rate variability (HRV), to study drug influences on neurohumoral activation and autonomic tone. Systemic vascular resistance significantly decreased during saterinone infusion, accompanied by a decrease in systemic blood pressure (both p values < 0.05) and an increase in heart rate (p = 0.05). Filling pressures also decreased during saterinone, but this was statistically significant only for pulmonary capillary wedge pressure, whereas the cardiac index remained unaffected. Plasma neurohormones (norepinephrine, epinephrine, and renin activity) were not significantly influenced by saterinone. HRV analysis revealed no significant effect of saterinone on autonomic tone. These results suggest that intravenous saterinone has a significant vasodilating effect in patients with moderate to severe chronic heart failure (CHF), without exerting an adverse effect on the autonomic nervous system, as demonstrated by assessment of plasma neurohormones and HRV analysis.

Aged↗
PubMed1997

The effect of training on the interpretation of 99Tcm-sestamibi myocardial perfusion SPET in patients with suspected coronary artery disease.

The aim of this study was to examine the effect of a period of concentrated training in nuclear cardiology on the accuracy of reporting 99Tcm-sestamibi (99Tcm-MIBI) single photon emission tomographic (SPET) images. Two visiting cardiologists, with no previous experience in nuclear cardiology, were asked to report blindly 60 99Tcm-MIBI SPET scans after 2 weeks of training in nuclear cardiology. One (observer 2) reported the same scans blindly after 2 months of further training. The results were compared with the assessment made by two experienced nuclear cardiologists and by using kappa statistics. Kappa values for the overall interpretation of the scan (normal or abnormal), segmental analysis (normal, ischaemic, fixed or mixed) and the three arterial territories were 0.7, 0.58 and 0.67 respectively. Following 2 months of further intensive training of observer 2, the kappa values were 0.857, 0.78 and 0.91 respectively. The difference between the two readings of observer 2 was significantly different for the segmental analysis (P < 0.001) and arterial territories (P = 0.006) but it did not reach statistical significance for the overall interpretation (P = 0.7). Thus, cardiologists without previous interpretation skills in nuclear cardiology required about 2 months of intensive training to achieve good accuracy in the interpretation of 99Tcm-MIBI SPET images. Accordingly, these techniques can be established in centres other than tertiary sites.

Adrenergic beta-Agonists↗
PubMed1997

A study of perinatal mortality and associated maternal profile in a medical college hospital.

Study of perinatal mortality in a Medical College Hospital revealed stillbirth rate as 38.4, early neonatal death rate as 29.3 and overall perinatal morality rate as 67.7 per 1000 live births. More than half (53.6%) of the perinatal deaths were in primipara and another 22.8% in mothers of parity more than 3. Most mothers (85.9%) did not receive adequate antenatal care services. On admission 35.1% mothers presented with some risk factors. The major risk factors identified were toxaemia of pregnancy (14.8%), severe anaemia (13%) and antepartum haemorrhage (2.6%).

Adolescent↗
PubMed1996

Prognostic value of stress dobutamine technetium-99m sestamibi single-photon emission computed tomography (SPECT) in patients with suspected coronary artery disease.

Inotropic stress using graded dobutamine infusion has evolved as an alternative form of pharmacologic stress in conjunction with perfusion and functional imaging for evaluation of coronary heart disease. However, the prognostic value of technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) imaging in patients undergoing dobutamine stress testing for the detection of coronary artery disease is unclear. Accordingly, 61 patients undergoing coronary arteriography for the evaluation of chest pain on the basis of symptoms and treadmill exercise electrocardiography underwent SPECT imaging at rest and during stress. Patients were followed up for 19 +/- 11 months (2 to 33) during which 2 died, 2 had acute myocardial infarction, 13 developed unstable angina, and 3 had congestive heart failure. Univariate Cox regression analysis revealed that those with reversible defects (95%) and defects in multiple vascular territories (80%) on SPECT had a greater number of cardiac events compared to those without (59% [p = 0.02] and 34% [p = 0.002], respectively). The number of reversible (3.9 +/- 2.1) and fixed (2.3 +/- 2.0) segments (12-segment model) were greater in patients with cardiac events compared to those without, (2.3 +/- 2.5, p = 0.009 and 1.1 +/- 2.0, p = 0.02) respectively. When multivariate analysis was performed using clinical, exercise testing, and SPECT variables, the independent predictors of cardiac events were a history of myocardial infarction (p <0.001), number of reversible segments (p = 0.001), and presence of defects in multiple vascular territories (p = 0.01). In summary, dobutamine stress Tc-99m sestamibi SPECT is a powerful predictor of future cardiac events in patients undergoing coronary arteriography for evaluation of chest pain and may be used to stratify patients for further intervention.

Aged↗
PubMed1996

Value of thallium-201 imaging in detecting adverse cardiac events after myocardial infarction and thrombolysis: a follow up of 100 consecutive patients.

OBJECTIVE: To determine the prognostic role of thallium-201 imaging compared with that of exercise electrocardiography in patients with acute myocardial infarction treated by thrombolysis. DESIGN: Patients who remained free of adverse cardiac events six weeks after myocardial infarction had stress and rest 201TI imaging and exercise electrocardiography and were followed up for 8-32 months. Adverse cardiac events (death, reinfarction, unstable angina, and congestive heart failure) were documented. SETTING: Large district general hospital, Middlesex. SUBJECTS: 100 consecutive male and female patients who were stable six weeks after thrombolysis for myocardial infarction. MAIN OUTCOME MEASURES: Prediction of occurrence of adverse cardiac events after myocardial infarction by exercise cardiography and 201TI myocardial perfusion imaging. RESULTS: Reversible ischaemia on 201TI imaging predicted adverse cardiac events in 33 out of 37 patients with such events during follow up (hazard ratio 8.1 (95% confidence interval 2.7 to 23.8), P < 0.001). Exercise electrocardiography showed reversible ischaemia in 33 patients, of whom 13 had subsequent events, and failed to predict events in 24 patients (hazard ratio 1.1 (0.56 to 2.2), P = 0.8). CONCLUSION: 201TI imaging is a sensitive predictor of subsequent adverse cardiac events in patients who have received thrombolysis after acute myocardial infarction, whereas exercise electrocardiography fails to predict outcome.

Adult↗
PubMed1996

Prognostic value of predischarge exercise testing, ejection fraction, and ventricular ectopic activity in acute myocardial infarction treated with streptokinase.

The relative importance of prognostic parameters that delineate left ventricular function, myocardial ischemia, and arrhythmogenic potential after thrombolytic therapy is not clear. This study investigated 112 patients with acute myocardial infarction who were treated with thrombolysis to determine the relative prognostic value of predischarge treadmill exercise testing, radionuclide ventriculography, and ambulatory electrocardiographic monitoring for ventricular ectopic activity. During a mean follow-up period of 18 months (range 6 to 30), 42 first cardiac events were recorded, consisting of 3 deaths, 6 reinfarctions, 16 bouts of unstable angina, 16 episodes of heart failure, and 1 arrhythmic event. Univariate analysis revealed ejection fraction, exercise time, and ventricular ectopic count of > or = 10/hour to be predictive of future cardiac events. Subsequent multivariate analysis showed ejection fraction (p <0.001) and exercise time (p=0.002 to have independent prognostic value, but ventricular ectopic activity did not provide additional information. Ventricular ectopic count > or = 10/hour was additionally predictive only when combined with either ejection fraction (R2=5.4%) or exercise time (R2=2.9%). Event-free survival analysis revealed hazard ratios for ejection fraction <40% and exercise time <7 minutes of 3.63 (p=0.001) and 2.16 (p=0.01), respectively. Although ejection fraction and exercise time were able to predict future episodes of heart failure, neither could adequately identify patients at risk of recurrent ischemic events.

Aged↗