Biomedical subjects

J Keegan

Publications and source records attributed to J Keegan.

At least 37 records · Page 2Linked to original sources

PubMed1999

Differences between normal subjects and patients with coronary artery disease for three different MR coronary angiography respiratory suppression techniques.

A comparison between three magnetic resonance coronary angiography (MRCA) respiratory motion suppression techniques was performed for both normal subjects and patients with coronary artery disease (CAD). MRCA images were acquired in 17 normal subjects and 15 patients with CAD, using conventional breath-hold MRCA, navigator echo (NE)-guided breath-hold MRCA (LED feedback), and NE-gated MRCA during free respiration. Image quality, diaphragm registration, and total acquisition time were assessed. Overall, there was poor diaphragm registration for conventional breath-holding compared with free respiration (P < 0.001). CAD patients found it significantly more difficult to perform a steady breath-hold (P = 0.04) or attain the same diaphragm position over multiple breath-holds than normal subjects (P = 0.02). All normal subjects, but only 3 of the 15 CAD patients, were able to perform the LED feedback technique (P < 0.001). For normal subjects, image quality was similar between the three respiratory suppression techniques (P = 0.3), while for CAD patients there was an improvement in image quality, for images acquired during free respiration (breath-hold vs. free respiration, P < 0.01). There was no significant difference in the total acquisition times between the breath-hold and free respiration techniques (P = 0.2). There were substantial differences in the effectiveness of MRCA respiratory suppression techniques between normal subjects and CAD patients. In patients, only NE-gated MRCA performed well, requiring minimal cooperation with no increase in total acquisition time. Validation of NE-MRCA techniques should always be performed in patients, as well as normal subjects, to ensure correct evaluation of the technique for the target population.

Adult↗

PubMed1999

First-pass myocardial perfusion imaging and equilibrium signal changes using the intravascular contrast agent NC100150 injection.

In this phase I clinical study, the new ultrasmall superparamagnetic iron oxide contrast agent, NC100150 Injection (Nycomed AS, Oslo, Norway, a part of Nycomed Amersham), was assessed for first-pass magnetic resonance myocardial perfusion studies and its ability to produce equilibrium signal changes, as a possible indicator of myocardial blood volume. Data were acquired in 18 healthy male volunteers at 0.5 T and 1.5 T. At both field strengths, first-pass studies using T1-weighted sequences were acquired. Long TE spin-echo echoplanar imaging (EPI) was used at 0.5 T and short TE fast low-angle shot (FLASH) imaging at 1.5 T. With both sequences, T1 effects dominated the images for low doses, and time intensity curves potentially suitable for perfusion analysis were generated. At higher doses, T2 and T2* effects were observed. At 1.5 T, these predominantly affected the blood pool signal; however, at 0.5 T the myocardial signal was also involved, reflecting the relative T2 and T2* sensitivity of the spin-echo EPI sequence as a result of the long TE and long readout window, respectively. Equilibrium changes were assessed at both field strengths using T1-weighted FLASH sequences and in addition at 1.5 T using T2*-weighted gradient-echo EPI. With the T1-weighted images at both field strengths, signal changes were observed in all subjects; however, no dose-response relationship could be shown. With the T2*-weighted EPI there was significantly lower signal (P < 0.05) with the 3 and 4 mg/kg doses than with the 2 mg/kg dose. In conclusion, NC100150 Injection is useful for first-pass myocardial perfusion using T1-weighted sequences; however, low doses in combination with short TE sequences are required to minimize sensitivity to T2* effects. Equilibrium signal changes can also be induced in the myocardium. More work is required to optimize the imaging sequences and dose of NC100150 Injection for first-pass studies and also to determine whether the equilibrium signal changes can be used to measure myocardial blood volume changes in ischemic heart disease.

Adult↗

PubMed1999

Coronary artery imaging in a 0.5-Tesla scanner: implementation of real-time, navigator echo-controlled segmented k-space FLASH and interleaved-spiral sequences.

Coronary angiography techniques have been implemented on a 0.5-Tesla scanner with a view to performing coronary artery imaging. Slice-followed, segmented k-space FLASH sequences and interleaved-spiral sequences have been employed with acquisitions under real-time navigator echo control with patient feed back, enabling poor signal-to-noise levels to be overcome by averaging data acquired over multiple, variable-length, reproducible breath holds. Good-quality, millimetre-resolution coronary images were obtained in ten normal subjects with both techniques. The mean percent of data segments or interleaves acquired with the navigator echo within the 5-mm diaphragm acceptance window was 57% [standard deviation (S.D.), 11%; range, 38-85%], and the average image-acquisition times were 123+/-22 sec and 71+/-14 sec for segmented FLASH and interleaved-spiral imaging, respectively. In addition to shorter acquisition times, the interleaved-spiral sequence has superior temporal resolution, allowing the acquisition of limited, multislice data sets. However, the sequence is particularly sensitive to the off-resonance effects of residual epicardial fat surrounding the artery and to field nonuniformities, both of which lead to image blurring and, unlike segmented FLASH acquisitions (which are very robust), the spiral data sets generally require postprocessing.

Adult↗

PubMed1999

3D coronary artery imaging with phase reordering for improved scan efficiency.

Three-dimensional (3D) coronary imaging has the potential to overcome problems resulting from vessel tortuosity and to reduce partial volume effects. With these techniques, however, acquisition times are long and respiratory motion artifacts problematical. This work describes the development of a method that applies phase encode reordering to 3D acquisitions, allowing larger navigator acceptance windows to be used, with a consequent reduction in acquisition time. This method is compared with navigator acceptance window methods (the acceptance-rejection algorithm and the diminishing variance algorithm) and the retrospective respiratory gating technique, both in vitro and in vivo. The use of phase reordering with a 10 mm acceptance window provided a significant increase in scan efficiency over a non-reordered 5 mm method (P<0.001) with no significant change in image quality, and a significant increase in image quality compared with a non-reordered image acquired in the same time (P<0.05). A significant improvement in both image quality and scan efficiency was demonstrated over the retrospective respiratory gating method (P<0.05).

Adult↗

PubMed1999

Motion-selective encoding for fast cine imaging.

In magnetic resonance (MR) cine imaging applications, it is common that only a fraction of the field of view is used for delineating dynamic features whereas surrounding static structures are merely served as landmarks for three-dimensional orientation. This paper presents a method of using motion-selective encoding for fast cine imaging. By the use of a simple RF saturation pulse, the imaging field of view was divided into two areas, one with motion and the other without. This allowed the static material to be imaged by fast ungated acquisition and dynamic structures by reduced phase encoding. Issues related to phase error correction were addressed and the proposed algorithm was validated using images acquired from five normal subjects. The saving in imaging time was dependent on the size of the moving structures and a 35% reduction in imaging time did not cause visually noticeable changes in image quality. The application of the technique is limited to cine images with large surrounding static structures and a theoretical analysis of maximum savings in imaging time in relation to the size of the moving structures within the image field of view is provided. Magn Reson Med 42:430-435, 1999.

Adult↗

PubMed1999

Use of the intravascular contrast agent NC100150 injection in spin-echo and gradient-echo imaging of the heart.

This is the first study of the intravascular iron oxide particle contrast agent, NC100150 Injection (Nycomed Imaging AS, Oslo, Norway, a part of Nycomed Amersham) in magnetic resonance imaging of the human heart. Eighteen healthy male volunteers were studied at both 0.5 and 1.5 T before and after the administration of NC100150 Injection. Transaxial spin-echo images were acquired at both field strengths, conventional gradient-echo cine images at 0.5 T, and breathhold Turbo-FLASH cine images at 1.5 T. Optimized cine imaging sequences were used postcontrast, with a high flip angle of 60-70 degrees. In the spin-echo images there was a significant reduction in the blood pool flow artifact at the level of the right atrium (0.5 T, 57%, p < 0.01; 1.5 T, 41%, p = 0.01) and the left ventricle (LV) (0.5 T, 45%, p = 0.01; 1.5 T, 45%, p < 0.01). In the conventional gradient-echo cines at 0.5 T, there was a significant increase in the LV blood pool and myocardial signal difference-to-noise ratio (SDNR) in the diastolic (56%, p = 0.01) and systolic (141%, p < 0.001) frames. There was also a significant increase in the signal intensity (SI) gradient at the LV blood pool-myocardial border in the diastolic and systolic frames (both p < 0.001). At higher doses of NC100150 Injection (3 and 4 mg/kg), a rim of signal void around the LV blood pool was observed, perfectly defining the LV blood pool-myocardial border. In the Turbo-FLASH breathhold cines at 1.5 T, there was a significant increase in the LV blood pool-myocardial SDNR in the diastolic (221%, p < 0.001) and systolic (916%, p < 0.001) frames. Again, there was also a significant increase in the SI gradient at the LV blood pool-myocardial border in the diastolic and systolic frames (both p = 0.003). In conclusion, NC100150 Injection was given safely to 18 healthy subjects. Image quality and LV blood pool-myocardial definition were improved after the administration of NC100150 Injection. These improvements enable better spin-echo anatomical definition, better definition of myocardial wall motion, and should improve the capability of automated edge detection algorithms.

Adult↗

PubMed1999

Calculation of a subject-specific adaptive motion-correction factor for improved real-time navigator echo-gated magnetic resonance coronary angiography.

There has been conflicting data in the literature regarding the use of wide navigator echo (NE) acceptance windows in combination with adaptive motion correction for magnetic resonance coronary angiography (MRCA). This in part may be due to the use of a fixed correction factor when applying the adaptive motion-correction algorithm, which may potentially result in miscorrection of the imaging slice in subjects whose correction factor differs widely from the mean. We have addressed this issue by measuring the superior/inferior correction factor in 25 subjects and assessing the effect of using a subject-specific correction factor (CFss) for MRCA in comparison with no adaptive motion correction (CF0) and erroneous adaptive motion correction with a correction factor of 1.0 (CF1). There was a wide variation in the correction factor between subjects (proximal right coronary artery, 0.49 +/- 0.15, range 0.20-0.70; proximal left coronary artery, mean 0.59 +/- 0.15, range 0.20-0.85). The subject-specific correction factor was accurately calculated from motion of the aortic root in the coronal plane between expiratory and inspiratory breathhold (correction factor calculated from coronal image versus correction factor calculated after localization of coronary arteries, r = 0.92, p < 0.001). MRCA image quality was improved using a subject-specific correction factor, for both a 6-mm NE acceptance window (CFss versus CF0, p = 0.008; CFss versus CF1, p = 0.02) and a 16-mm NE window (CFss versus CF0, p = 0.01; CFss versus CF1, p = 0.007). Furthermore, image quality was maintained between the two NE windows if the subjects-specific correction factor was used (6 versus 16 mm, p = 0.21), with an improvement in scan efficiency (6 versus 16 mm, 49 +/- 17% versus 81 +/- 22% respectively, p < 0.001). Thus, for adaptive motion correction to be implemented, a subject-specific correction factor should be used and calculated from simple coronal expiratory and inspiratory breathholds. For real-time NE-gated cardiac MR with adaptive motion correction, the NE window can be widened to reduce the acquisition period without loss of image quality.

Adult↗

PubMed1998

New helper cells and matched early region 1-deleted adenovirus vectors prevent generation of replication-competent adenoviruses.

The presence of replication-competent adenoviruses (RCAs) in batches of replication-defective adenovirus (Ad) vectors is a major problem for the application of these vectors in gene therapy. RCAs are generated by recombination between sequences in the Ad vector and homologous Ad sequences in the helper cells, resulting in the acquisition by the vector of early region 1. To prevent the formation of RCAs, we have developed helper cell lines, which we named PER, and matched Ad vectors that do not have sequence overlap. PER cells contain the Ad serotype 5 (Ad5) E1A- and E1B-encoding sequences (Ad5 nucleotides 459-3510) under the control of the human phosphoglycerate kinase (PGK) promoter. We demonstrate that PER cells synthesize high levels of the Ad5 E1A and E1B proteins. The yields from PER cells of E1-deleted Ads are similar to those obtained from earlier helper cells, such as 911 and 293 cells. Propagation of matched Ad vectors, which lack Ad5 nucleotides 459-3510, in one of the PER clones, PER.C6, does not result in the generation of RCAs, in contrast to propagation in 293 cells. We conclude that the combination of PER.C6 cells and nonoverlapping E1-deleted adenoviral vectors eliminates the problem of RCA generation by homologous recombination, and allows cost-effective production of safe, clinical-grade batches of recombinant Ad vectors.

Adenovirus E1A Proteins↗

PubMed1998

Three-dimensional coronary MR angiography using zonal echo planar imaging.

Using an adapted two-dimensional spatially selective RF excitation scheme, a novel yet practical three-dimensional (3D) zonal echo-planar imaging technique for MR coronary angiography has been developed. The robustness of the technique compared with the two-dimensional (2D) segmented fast low angle shot (FLASH) method was evaluated using the right coronary artery images of 16 asymptomatic volunteers with a 0.5-T mobile scanner. Each 3D acquisition required multiple breath-holds, and real-time navigator echoes were used to ensure consistent breath-holding. Advantages of the technique include an improved signal-to-noise ratio, clearer depiction of tortuous coronary vessels due to decreased partial volume effects, and reduced motion blurring by the use of a short echo-planar readout.

Adult↗

PubMed1998

Community-based mental health care: bridging the gap between community care and primary care.

Australian nursing is undergoing major changes in practice, education and research in a climate of burgeoning health-care costs, and changing priorities and service directions. The government is searching for new ways to deliver services that are appropriate and equitable while focusing on containing costs. These are signs that it is an opportune time for nurses to test new roles, and one suggested way to provide extra cost-effective service is through the use of nurse practitioners. In order to improve the delivery of mental health services, the nurse practitioner specializing in mental health can provide a link between the community and the primary care provided by general practitioners. A proposed model for nurse practitioners in mental health is presented as a means of bridging this gap.

Community Health Nursing↗

PubMed1997

Non-breath-hold lung magnetic resonance imaging with real-time navigation.

Magnetic resonance imaging (MRI) with navigating techniques based on consecutive breath-holds demand a level of respiratory control that is often beyond the capability of patients with lung disease. The objectives of this investigation were to develop and evaluate a navigating technique for lung MRI that does not rely on patient cooperation. Navigating techniques were implemented at 0.5 T using conventional imaging techniques of short echo-time and imaging during normal breathing in the diastolic phase of the cardiac cycle. A column of spins, orthogonal to the diaphragm, was excited both immediately before and after the imaging segment. These signals were processed in real time to provide the position of the lung-diaphragm interface. An imaging segment was considered correctly acquired only when the interface position was within the acceptance window both before and after the acquisition of the segment. A distribution of lung-diaphragm interface positions obtained during normal respiration was employed to define the acceptance window. In the case of multislice techniques, the position of the lung-diaphragm interface immediately before the imaging segment was also employed to decide which phase-encoding step to acquire next, therefore reducing the apparent frequency of the respiratory motion. A distribution of interface positions, updated in real time, served as a reference for the allocation of phase-encoding steps according to diaphragm position. The lung images obtained represent a significant advance in image quality, improving further the ability of MR to detect and monitor pulmonary disease. Motion artifacts were reduced, and images reliably demonstrated smaller vessels, which are not normally visible without navigation.

Computer Systems↗

PubMed1996

Magnetic resonance coronary angiography in heart transplant recipients.

BACKGROUND: Magnetic resonance angiography (MRA) using segmented k-space fast low-angle shot imaging has recently been used to demonstrate the proximal coronary arteries in healthy subjects and in patients with coronary artery disease. We assessed the sensitivity and specificity of coronary MRA in heart transplant recipients and investigated the feasibility of coronary MRA in patients with metallic sutures and clips in the chest. MATERIALS AND METHODS: Sixteen cardiac transplant patients aged 57.2 +/- 7.9 years (mean +/- SD) were recruited. Forty-eight arterial segments were evaluated, including the left main artery (LMA), left anterior descending artery (LADA) and right coronary artery (RCA). We excluded the left circumflex artery which could not be imaged accurately. The average time between heart transplant operation and MRA was 6 years, whereas that between MRA and X-ray angiography was 4 months. The coronary MRA was interpreted by two experienced investigators who were blinded to the coronary X-ray angiography results. Similarly, the coronary X-ray angiography results were interpreted by two experienced investigators blinded to the MRA results. The coronary arterial segments were classified by MRA as being normal or as having an amount of disease that was significant (> 50% lesion) or insignificant (< 50% lesion). RESULTS: There were 28 true-negative, five true-positive, four false-negative and six false-positive results. Of the 28 true-negative cases, 13 were in the LMA, six in the LADA and nine in the RCA. There was one false-positive LMA, two false-positive LADA and three false-positive RCA stenoses. There were four false-negative results in the LADA and one in the RCA. Clips precluded evaluation in one LMA, one LADA and one RCA. One LMA and one LADA were not evaluated as a result of poor images. One false-positive RCA stenosis was caused by a metallic clip. Three of the false-negative LADA stenoses had lesions in the distal third of the artery. The sensitivity, specificity, negative and positive predictive values were generally poor for the left coronary artery. The best results were for the RCA (sensitivity 100%, specificity 75%, positive predictive value 50% and negative predictive value 100%). The specificity in the left coronary arteries (LMA and LADA) was 86%, but the other indicators were all poorer. For the RCA, LMA and LADA combined, the overall sensitivity was 56%, specificity 82%, predictive accuracy 45% and negative predictive value 88%. In three patients, < 50% RCA lesions were seen in the MRA data, which were all confirmed by angiography. No < 50% lesions were seen in the LMA or in the LADA by MRA or by X-ray angiography. CONCLUSION: Coronary MRA using the segmented fast low-angle shot technique is feasible in heart transplant recipients but the sensitivity and specificity of this method are limited. Further developments in coil design, rapid imaging techniques and respiratory monitoring methods are necessary to improve the accuracy of coronary MRA.

Aged↗

PubMed1996

Molecular characterization of replication-competent variants of adenovirus vectors and genome modifications to prevent their occurrence.

Adenovirus (Ad) vectors for gene therapy are made replication defective by deletion of E1 region genes. For isolation, propagation, and large-scale production of such vectors, E1 functions are supplied in trans from a stable cell line. Virtually all Ad vectors used for clinical studies are produced in the 293 cell, a human embryonic kidney cell line expressing E1 functions from an integrated segment of the left end of the Ad type 5 (Ad5) genome. Replication-competent vector variants that have regained E1 sequences have been observed within populations of Ad vectors grown on 293 cells. These replication-competent variants presumably result from recombination between vector and 293 cell Ad5 sequences. We have developed Ad2-based vectors and have characterized at the molecular level examples of replication-competent variants. All such variants analyzed are Ad2-Ad5 chimeras in which the 293 cell Ad5 E1 sequences have become incorporated into the viral genome by legitimate recombination events. A map of Ad5 sequences within the 293 cell genome developed in parallel is consistent with the proposed recombination events. To provide a convenient vector production system that circumvents the generation of replication-competent variants, we have modified the Ad2 vector backbone by deleting or rearranging the protein IX coding region normally present downstream from the E1 region such that the frequency of recombination between vector and 293 cell Ad5 sequences is greatly reduced. Twelve serial passages of an Ad2 vector lacking the protein IX gene were carried out without generating replication-competent variants. In the course of producing and testing more than 30 large-scale preparations of vectors lacking the protein IX gene or having a rearranged protein IX gene, only three examples of replication-competent variants were observed. Use of these genome modifications allows use of conventional 293 cells for production of large-scale preparations of Ad-based vectors lacking replication-competent variants.

Adenovirus E1 Proteins↗

PubMed1996

Assessment of coronary artery stenosis by magnetic resonance imaging.

OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient echo imaging technique incorporating fat suppression was used in 39 patients (55 coronary stenoses) with known coronary artery disease. RESULTS: Overall, 47 stenoses (85%) were assessed by magnetic resonance (29 of 33 stenoses in the left anterior descending artery, one of one in the left main stem, 14 of 17 in the right coronary artery, and three of four in the left circumflex artery were detected). There was close agreement between magnetic resonance and x-ray angiography for the distance of the stenosis from the arterial origin (magnetic resonance mean (SD) 27 (16) mm versus x-ray angiography 27 (16) mm, P = NS, mean difference -0.2 mm). The distance to 39 stenoses (83%) agreed to within 5 mm, with increased scatter for more distal stenoses. The severity of magnetic resonance signal loss, assessed visually at the site of stenosis, varied significantly according to the percentage diameter stenosis (F = 30, P < 0.0001); stenosis severity with severe signal loss was 89 (7)%, with partial signal was 70 (16)%, and with irregular wall only 37 (11)%, with significant differences among the three groups (P < 0.001). A significant correlation was found between the proportional magnetic resonance signal loss at the stenosis and the percentage diameter stenosis severity (r = -0.67, P < 0.0001). The length of stenosis measured by magnetic resonance (6 (3) mm) was greater than by x-ray angiography (5 (2) mm, P < 0.006, mean difference +1.1 mm). Spearman's rank test showed that there was significant overestimation of stenosis length by magnetic resonance as stenosis severity increased (rs = 0.34, P < 0.02). CONCLUSIONS: Accurate localisation of coronary stenosis and a qualitative assessment of stenosis severity are possible by magnetic resonance, but stenosis length is overestimated as severity increases, probably because of disturbed patterns of flow with turbulence distal to severe stenoses. Reasonable results for the detection of coronary artery stenosis by magnetic resonance were achieved in this highly selected population, but further progress in imaging techniques is necessary before moving towards appreciable clinical application.

Angina Pectoris↗

PubMed1996

Identification of n-acetylmethamphetamine in a sample of illicitly synthesized methamphetamine.

Analysis of illicit methamphetamine samples revealed the presence of a hitherto unreported impurity. This was identified as N-acetylmethamphetamine by synthesis and GC-MS. This impurity is believed to arise by transesterification of methamphetamine during reflux with propyl acetate. Other circumstantial evidence and intelligence data indicate that propyl acetate was used to increase yields of methamphetamine hydrochloride by azeotropic removal of water remaining after salt formation with aqueous hydrochloric acid.

Drug Contamination↗

PubMed1995

Left ventricular volume in thrombolysed patients with acute anterior myocardial infarction: the effect of captopril and xamoterol.

We measured left ventricular volume in 70 asymptomatic patients after first Q-wave anterior myocardial infarction in order to determine whether ventricular dilatation occurs and whether there is evidence for its attenuation or prevention by treatment with captopril or xamoterol--PRevention Of VEntricular Dilatation?: the PROVED? study. 77% of patients received thrombolytic treatment. Patients were randomised a mean of 11 days after infarction to receive either captopril 25 mg three times daily, xamoterol 200 mg twice daily or matching placebo. After 6 months of treatment, 6 patients from the placebo group (n = 24), 1 from the captopril group (n = 23) and 3 from the xamoterol group (n = 23) had been withdrawn from the study because of clinical complications. Left ventricular volume was measured using magnetic resonance imaging, before randomisation and after 6 months of treatment. Changes in left ventricular end-diastolic and end-systolic volume after 6 months of treatment were defined prospectively as the primary endpoints. Mean initial end-diastolic volume index was 85 (S.D. 19) ml/m2, mean end-systolic volume index was 45 (S.D. 18) ml/m2, and mean ejection fraction was 48 (S.D. 11)% for the whole group. There was no significant change in left ventricular volume index in the placebo or either treatment group after 6 months of treatment. Only minimal left ventricular dilatation was evident at 11 days. No further increase in left ventricular volume occurred after six months and there was no additional benefit from treatment with either captopril or xamoterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗

PubMed1994

The application of breath hold phase velocity mapping techniques to the measurement of coronary artery blood flow velocity: phantom data and initial in vivo results.

A segmented kappa-space breath hold phase velocity mapping technique has been developed for the study of coronary artery blood flow velocity. In vitro validation has been performed using a number of pulsatile flow phantoms and the accuracy of the technique for determining the velocity increase at the site of a stenosis demonstrated in several phantom models. Examples of both in-plane and through-plane velocity maps of the left anterior descending and right coronary arteries of normal subjects in early diastole are presented. In one subject, through-plane velocity maps were obtained in the right and left anterior descending arteries throughout the cardiac cycle in order to generate flow velocity time curves. The problems associated with coronary artery velocity mapping are discussed.

Artifacts↗

PubMed1993

Atenolol or nicardipine alone is as efficacious in stable angina as their combination: a double blind randomised trial.

BACKGROUND: Beta blockers and calcium antagonists are widely used in the management of angina pectoris in the belief that the combination is more efficacious than either drug alone. METHODS: This double blind randomised crossover placebo controlled study compares the effects of nicardipine, atenolol and their combination in 30 patients with chronic stable angina. Each treatment period lasted 6 weeks with dose titration after 3 weeks. Symptom limited treadmill exercise testing and radionuclide ventriculography at rest was carried out at the end of each treatment period. RESULTS: Total exercise duration and time to 1-mm ST-segment depression was significantly prolonged by nicardipine and atenolol when compared to placebo, the combination offered no additional benefit. Time to onset of angina was significantly prolonged by nicardipine and the combination but not by atenolol. Indices of left ventricular function were not significantly affected by any treatment other than an increase in left ventricular end diastolic volume on atenolol and the combination. CONCLUSIONS: Nicardipine and atenolol are equally effective in prolonging exercise duration and time to onset of ischemia in patients with chronic stable angina while the combination appeared to offer no additional benefit. Nicardipine prolonged the time to onset of angina significantly; again there was no further improvement with the combination. Neither drug appears to have an important effect on the parameters of diastolic function studied in patients with chronic stable angina.

Adult↗