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Biomedical subjects

K Niemelä

Publications and source records attributed to K Niemelä.

At least 19 recordsLinked to original sources
PubMed2004

Improved adherence to practice guidelines yields better outcome in high-risk patients with acute coronary syndrome without ST elevation: findings from nationwide FINACS studies.

OBJECTIVES: Treatment options for acute coronary syndrome (ACS) without ST elevation have evolved rapidly during the recent years, but the successful implementation of practice guidelines incorporating new treatments into practice has been challenging. In this study, we evaluate whether targeted educational intervention could improve adherence to treatment guidelines of ACS without ST elevation. DESIGN, SETTING AND SUBJECTS: A previous study, FINACS I, evaluated the treatment and outcome of 501 consecutive non-ST elevation ACS patients that were referred in early 2001 to nine hospitals, covering nearly half of the Finnish population. That study revealed poor adherence to ESC guidelines, so targeted educational intervention on optimal practice was arranged before the second study (FINACS II), which was performed in the same hospitals using the same protocol as FINACS I. FINACS II, undertaken in early 2003, evaluated 540 consecutive patients. Interventions. Targeted educational programmes on optimal practice. MAIN OUTCOME MEASURES: The use of evidence-based therapies in non-ST elevation ACS patients. In-hospital event-free (death, new myocardial infarction, refractory angina, readmission with unstable angina and transient cerebral ischaemia/stroke) survival, and event-free survival at 6 months. RESULTS: Baseline characteristics and risk markers were similar in both studies, and no significant changes in resources were seen. In 2003, the in-hospital use of statins, ACE-inhibitors, clopidogrel and glycoprotein (GP) IIb/IIIa receptor antagonists increased significantly, and in-hospital angiography was performed more often, especially in high-risk patients (59% vs. 45%, P < 0.05); waiting time also shortened (4.2 +/- 5.5 vs. 5.8 +/- 4.7 days, P < 0.01). Overall no significant change was seen in the frequency of death either in-hospital (2% vs. 4%, P = NS) or at 6 months (7% vs. 10%, P = NS) in FINACS II. However, the survival of high-risk patients improved both in-hospital (95% vs. 90%, P = 0.05) and at 6 months (89% vs. 78%, P = 0.05). CONCLUSION: In patients with non-ST elevation ACS-targeted educational interventions appeared to be associated with improved adherence to practical guidelines, which yielded a better outcome in high-risk ACS patients.

Acute Disease↗
PubMed2001

Half-polarized quantum hall states.

We report a theoretical analysis of the half-polarized quantum Hall states observed in a recent experiment. Our numerical results indicate that the ground state energy of the quantum Hall nu = 2 / 3 and nu = 2 / 5 states versus spin polarization has a downward cusp at half the maximal spin polarization. We map the two-component fermion system onto a system of excitons and describe the ground state as a liquid state of excitons with nonzero values of exciton angular momentum.

Journal Article↗
PubMed1998

Correct utilization of exercise electrocardiographic leads in differentiation of men with coronary artery disease from patients with a low likelihood of coronary artery disease using peak exercise ST-segment depression.

In this study we compared the diagnostic characteristics of the individual exercise electrocardiographic leads, 3 different lead sets comprising standard leads and the effect of the partition value in the detection of coronary artery disease (CAD). The diagnostic variable used was ST-segment depression at peak exercise, and the study population consisted of 101 patients with CAD and 100 patients with a low likelihood of the disease. The lead system used was the Mason-Likar modification of the standard 12-lead system and exercise tests were performed on a bicycle ergometer. The comparisons were performed by means of receiver-operating characteristic analysis and by determining sensitivities at a fixed 95% specificity. These properties, defined here as diagnostic capacity, were the most efficacious in leads I, -aVR, V4, V5, and V6. Diagnostic capacities in leads aVL, aVF, III, V1, and V2 were quite poor; statistical comparisons indicated significant differences between these leads and lead V5 (p < or = 0.0001 in each case). Use of the maximum value of ST-segment depression at peak exercise derived from all 12 leads produced a considerable decrease in the diagnostic capacity of the exercise electrocardiogram compared with lead V5. The exclusion of leads aVL, V1, and III improved the diagnostic capacity compared with the 12-lead set, but it was still smaller than that of lead V5. With use of a lead set with the 5 best leads increased the diagnostic capacity over other lead sets and over any individual lead. Further improvement was noted when a 50% smaller partition value was applied to leads I and -aVR than for the other leads (p = 0.041). In conclusion, this study suggests that use of leads I, -aVR, V4, V5, and V6 is the most influential when differentiating between patients with CAD and patients with a low likelihood of disease using peak exercise ST-segment depression. The effective use of leads I and -aVR requires the partition value applied for these leads to be 50% smaller than that used for the lateral precordial leads.

Coronary Disease↗
PubMed1997

Effect of ST segment measurement point on performance of exercise ECG analysis.

To evaluate the effect of ST-segment measurement point on diagnostic performance of the ST-segment/heart rate (ST/HR) hysteresis, the ST/HR index, and the end-exercise ST-segment depression in the detection of coronary artery disease, we analysed the exercise electrocardiograms of 347 patients using ST-segment depression measured at 0, 20, 40, 60 and 80 ms after the J-point. Of these patients, 127 had and 13 had no significant coronary artery disease according to angiography, 18 had no myocardial perfusion defect according to technetium-99m sestamibi single-photon emission computed tomography, and 189 were clinically 'normal' having low likelihood of coronary artery disease. Comparison of areas under the receiver operating characteristic curves showed that the discriminative capacity of the above diagnostic variables improved systematically up to the ST-segment measurement point of 60 ms after the J-point. As compared to analysis at the J-point (0 ms), the areas based on the 60-ms point were 89 vs. 84% (p=0.0001) for the ST/HR hysteresis, 83 vs. 76% (p<0.0001) for the ST/HR index, and 76 vs. 61% (p<0.0001) for the end-exercise ST depression. These findings suggest that the ST-segment measurement at 60 ms after the J-point is the most reasonable point of choice in terms of discriminative capacity of both the simple and the heart rate-adjusted indices of ST depression. Moreover, the ST/HR hysteresis had the best discriminative capacity independently of the ST-segment measurement point, the observation thus giving further support to clinical utility of this new method in the detection of coronary artery disease.

Coronary Disease↗
PubMed1997

The effect of lead selection on traditional and heart rate-adjusted ST segment analysis in the detection of coronary artery disease during exercise testing.

Several methods of heart rate-adjusted ST segment (ST/HR) analysis have been suggested to improve the diagnostic accuracy of exercise electrocardiography in the identification of coronary artery disease compared with traditional ST segment analysis. However, no comprehensive comparison of these methods on a lead-by-lead basis in all 12 electrocardiographic leads has been reported. This article compares the diagnostic performances of ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise in a study population of 128 patients with angiographically proved coronary artery disease and 189 patients with a low likelihood of the disease. The methods were determined in each lead of the Mason-Likar modification of the standard 12-lead exercise electrocardiogram for each patient. The ST/HR hysteresis, ST/HR index, ST segment depression 3 minutes after recovery from exercise, and ST segment depression at peak exercise achieved more than 85% area under the receiver-operating characteristic curve in nine, none, three, and one of the 12 standard leads, respectively. The diagnostic performance of ST/HR hysteresis was significantly superior in each lead, with the exception of leads a VL and V1. Examination of individual leads in each study method revealed the high diagnostic performance of leads I and -aVR, indicating that the importance of these leads has been undervalued. In conclusion, the results indicate that when traditional ST segment analysis is used for the detection of coronary artery disease, more attention should be paid to the leads chosen for analysis, and lead-specific cut points should be applied. On the other hand, ST/HR hysteresis, which integrates the ST/HR depression of the exercise and recovery phases, seems to be relatively insensitive to the lead selection and significantly increases the diagnostic performance of exercise electrocardiography in the detection of coronary artery disease.

Coronary Disease↗
PubMed1996

Accurate detection of coronary artery disease by integrated analysis of the ST-segment depression/heart rate patterns during the exercise and recovery phases of the exercise electrocardiography test.

In this comparative cross-sectional study, we evaluated whether a novel computerized diagnostic variable, ST-segment depression/heart rate ST/HR analysis during both the exercise and postexercise recovery phases of the exercise electrocardiography (ECG) test, can detect coronary artery disease more accurately than methods using either exercise or recovery phase alone. The study population comprised 347 clinical patients referred for a routine bicycle exercise ECG test at Tampere University Hospital, Finland. Of these, 127 had angiographically proven coronary artery disease, whereas 13 had no coronary artery disease according to angiography, 18 had no perfusion defect according to technetium-99m sestamibi single-photon emission computed tomography, and 189 were clinically normal with respect to cardiac diseases. For each patient, the maximum values of the ST/HR hysteresis, ST/HR index, end-exercise ST depression, and recovery ST depression were determined from the Mason-Likar modification of the standard 12-lead exercise electrocardiogram [aVL, aVR, and V1 excluded]. The diagnostic performance of these continuous diagnostic variables was compared by means of receiver-operating characteristic analysis. The area under the receiver-operating characteristic curve of the ST/HR hysteresis was 89%, which was significantly larger than that of the end-exercise ST depression (76%, p < or = 0.0001), recovery ST depression (84%, p = 0.0063), or ST/HR index (83%, p = 0.0023), indicating superior diagnostic performance of the ST/HR hysteresis independent of the partition value selection. In conclusion, computerized analysis of the HR-adjusted ST depression pattern during the exercise phase, integrated with the HR-adjusted ST depression pattern during the recovery phase after exercise, can significantly improve the diagnostic performance and clinical utility of the exercise ECG test for the detection of coronary artery disease.

Adult↗
PubMed1995

Warm underwater water-jet massage improves recovery from intense physical exercise.

The effects of warm underwater water-jet massage on neuromuscular functioning, selected biochemical parameters (serum creatine kinase, lactic dehydrogenase, serum carbonic anhydrase, myoglobin, urine urea and creatinine) and muscle soreness were studied among 14 junior track and field athletes. Each subject spent, in a randomized order, two identical training weeks engaged in five strength/power training sessions lasting 3 days. The training weeks differed from each other only in respect of underwater water-jet massage treatments. These were used three times (20 min each) during the treatment week and not used during the control week. During the treatment week continuous jumping power decreased and ground contact time increased significantly less (P < 0.05) and serum myoglobin increased more than during the control week. It is suggested that underwater water-jet massage in connection with intense strength/power training increases the release of proteins from muscle tissue into the blood and enhances the maintenance of neuro-muscular performance capacity.

Adolescent↗
PubMed1994

Inhomogeneous exercise uptake and accelerated washout of a radioiodinated fatty acid analogue in syndrome X. A SPECT study of the left ventricle.

Myocardial metabolism in exercise was determined by studying 21 syndrome X patients and 14 healthy volunteers with an aromatic fatty acid analogue IPPA and a gamma camera. We developed criteria for visual semiquantitative assessment of relative segmental radiotracer uptake and washout, and tested a new computer program for quantitative evaluation. One volunteer (7%) and 12 patients (57%) showed visually inhomogeneous uptake (p = 0.006, chi 2-test) in SPECT polar tomograms after a maximal ergometry test. Images in none of the volunteers and seven patients (33%) gave the impression of a slowed regional washout (p = 0.057). Only six patients (29%) had a normal radial polarogram. Patients with irregular coronary angiograms (showing 'slow flow' or minor sclerosis) and those with chest pain during the IPPA exercise test had a very low frequency of normalcy, but this was not significant. Total washout was higher in patients than in the reference population, as the exercise to rest activity ratio was 1.36 SD 0.13 versus 1.25 SD 0.11 in computerized quantitation (p = 0.015, t-test). Washout did not correlate with age, sex or exercise heart rate. Regarding computerized analysis of uptake and slow washout, the number of deviant segments was not significantly higher in patients than in reference population. Semiquantitative and quantitative analysis correlated in the assessment of uptake, but not in the assessment of washout. Possible reasons for the discrepancy are discussed. Conclusions of this study are not straightforward. Syndrome X was associated with inhomogeneous IPPA uptake, which is not at variance with the theory of microvascular dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Performance characteristics of various exercise ECG classifiers in different clinical populations.

To improve the diagnostic power of the exercise electrocardiographic test in detecting myocardial ischemia, the authors have recently developed a diagnostic method called multivariate ST-segment/heart rate (ST/HR) analysis (MUSTA). The goal of this study was to evaluate the validity of MUSTA in different clinical populations and to compare its performance characteristics with ST-segment depression, the ST/HR slope, and the delta ST/HR index in these populations. The computerized exercise electrocardiographic measurements were performed on 1,507 cases, and 382 patients were selected as the study population: 161 with significant coronary artery disease according to coronary angiography and 221 with a low likelihood of coronary artery disease. The diagnostic accuracy of MUSTA in the pooled population was 77.7% (297 out of 382 patients), which was clearly better than the accuracy of 69.6% (266 out of 382 patients) using the conventional ST-segment depression criterion of 0.10 mV in detecting coronary artery disease and exercise-induced myocardial ischemia. According to receiver operating characteristics analysis, MUSTA had significantly better diagnostic power than the other classifiers. These findings suggest that multivariate and compartmental analysis methods like MUSTA can further improve the clinical importance of the exercise electrocardiogram.

Coronary Angiography↗
PubMed1994

Fatty acid exercise scintigraphy after percutaneous transluminal coronary angioplasty.

We performed a sequential fatty acid exercise-rest scintigraphy in 18 patients with an initially successful percutaneous transluminal coronary angioplasty (PTCA) to study the concordance of trends in symptoms, exercise tolerance and myocardial metabolism. Eleven patients stopped the exercise because of angina pectoris in the preoperative test; 2 days after PTCA this number decreased to two, but again increased to eight 3 months later. Exercise time (9.7 +/- 0.6 min, mean +/- SEM) and maximum exercise heart rate (128 +/- 4 beats min-1) were at least as good immediately after the operation as originally (8.8 +/- 0.6 min and 121 +/- 4 beats min-1, respectively). After 3 months both parameters were significantly (P < 0.05) better (10.3 +/- 0.6 min and 136 +/- 4 beats min-1, respectively) than originally. Some relative improvement in washout was noticed in 61% 2 days and in 56% of cases 3 months after PTCA. Fatty acid exercise uptake was more homogeneous in 72% of cases immediately after angioplasty and in 44% 3 months later. The trend in fatty acid uptake, exercise characteristics, and also in symptoms was most favourable among the eight patients with a dilatated left anterior descending coronary artery. Although the gamma camera technique possibly underestimated the effects of angioplasty, the impaired fatty acid metabolism could be linked with persistent symptoms after the operation. We conclude that most patients can safely participate in a symptom-limited (maximal) ergometry test already 2 days after PTCA, and that postoperatively myocardial perfusion and metabolism improve rapidly. However, this advantage is eventually lost to some degree, even if exercise tolerance continues to improve.

Adult↗
PubMed1994

Inferior epigastric artery as a conduit for myocardial revascularization.

In 18 patients the inferior epigastric artery (IEA) was used for myocardial revascularization along with the left internal mammary artery and saphenous vein (4.5 grafts/patient). Preoperative duplex scan assessment of IEA correctly predicted its distal diameter. At operation the mean internal diameter was 1.6 (1.5-2.0) mm distally and 2.1 (2.0-2.5) mm proximally. The mean in situ flow after intraluminal injection of papaverine was 115 (36-210) ml/min in IEA and 136 (56-210) ml/min in internal mammary artery. There was no perioperative death or myocardial infarction. Morbidity associated with IEA harvesting was minor: ultrasonography showed diastasis and slower contraction of the rectus muscle at the harvesting site than contralaterally in one case. The preoperative duplex scan was useful for evaluating IEA size. All the patients were clinically improved. The patency rate at selective IEA angiography 3 months post-operatively was 72% (13/18). This poor early patency of IEA in our small series raises doubts concerning the vessel's suitability for myocardial revascularization.

Abdominal Muscles↗
PubMed1990

High density lipoprotein cholesterol and triglycerides as markers of angiographically assessed coronary artery disease.

Serum triglycerides, high density lipoprotein (HDL) cholesterol, and total cholesterol were measured in 698 patients examined by angiography. The ratio of HDL cholesterol to total cholesterol was significantly lower in patients with single, double, and triple vessel disease than in patients without disease. The serum concentration of triglyceride was significantly higher in patients with single, double, and triple vessel disease than in those without coronary artery disease. Similar proportion of patients with coronary artery disease and without had serum cholesterol concentrations of greater than or equal to 6.5 mmol/l, but total cholesterol was significantly higher in patients with single, double, and triple vessel disease than in those without. HDL cholesterol (less than 1.0 mmol/l), triglycerides (greater than 2.0 mmol/l), and the ratio of HDL cholesterol to total cholesterol (less than 0.20) were significantly better than total cholesterol as indicators of coronary risk.

Adult↗
PubMed1987

Impaired left ventricular diastolic function in athletes after utterly strenuous prolonged exercise.

Digitized M mode echocardiography was used to evaluate the effect of a competitive 24-h run on the left ventricular diastolic function in 12 well-trained marathon runners who completed 146-227 km during the race. Mitral valve opening was delayed, early diastolic filling was decreased and prolonged, and posterior wall thinning was reduced, particularly among those athletes completing close to 200 km or more. Since the alterations were in part the opposite in those running 160 km or less, only the reductions in the peak rate of dimension increase (P less than 0.05) and posterior wall thinning (P less than 0.01) were significant in the group as a whole. The delay in mitral valve opening (r = 0.76), the decrease in the peak rate of dimension increase (r = -0.68), and the prolongation of the early diastolic filling period (r = 0.60) were correlated with the distance completed. The reductions in left ventricular end-diastolic dimension and fractional shortening were not in proportion to the distance run, however (r = 0.23 and 0.46, respectively). Measurements made on six athletes 2-3 days after the race showed reversal of the indices of left ventricular diastolic function. Extremely exhaustive prolonged exercise thus appears to result in a marked reversible impairment in left ventricular relaxation and filling. Since the effect of these abnormalities in cardiac filling during exercise is probably more important due to the shorter diastole, the prevention of hypohydration, which could otherwise further compromise left ventricular filling, becomes crucial.

Adult↗
PubMed1985

Determination of the anaerobic threshold in the evaluation of functional status before and following valve replacement for aortic regurgitation.

The effect of aortic valve replacement on exercise capacity was evaluated in 28 patients with aortic regurgitation using repeat determinations of peak oxygen uptake (VO2) and the anaerobic threshold (AT), based on a nonlinear increase in the plot of pulmonary ventilation versus VO2. Although the AT was on average 68% of peak VO2 before and 1 year after surgery, the test-to-test correlation coefficient was 0.92 for the AT but only 0.68 for peak VO2 postoperatively. 11 patients (39%) improved in AT, usually within the first 6 months. The preoperative echocardiographic left ventricular end-diastolic dimension and its postoperative change correlated with that in the AT (r = 0.64 and -0.60, p less than 0.001) but not with that in peak VO2. The patients likely to improve had a lower AT (p less than 0.05) preoperatively, however. Thus repeat determinations of AT using respiratory measurements give additional data on changes in functional status. Sequential exercise testing does not require the patient to be exercised much past his AT.

Adult↗
PubMed1983

Functional evaluation after aortic valve replacement.

Preoperative and sequential postoperative bicycle exercise tests were compared with clinical and catheterization data in assessment of the functional outcome of uncomplicated aortic valve replacement (AVR) in 33 patients. The operation was done because of aortic stenosis (AS) in 14 patients and aortic regurgitation (AR) in 19. Both groups of patients showed improved NYHA functional class and peak achieved workload after AVR, but the results in these respects did not correlate. Nor did the regression in left ventricular (LV) hypertrophy and dilatation after AVR that was seen in both patient groups correlate with the changes measured in exercise tolerance. Preoperative exercise capacity was not predictive of the postoperative performance. In the AR patients, however, preoperative ability to raise the systolic blood pressure during exercise appeared to predict which patients were likely to show enhanced resting LV systolic pump function after AVR. It is concluded that objective tests of exercise tolerance alone permit reliable evaluation of the functional outcome of uncomplicated AVR. Indices of resting LV performance, though helpful in observation of the changes resulting from removal of the untoward LV burden after AVR, are likely to be less useful for evaluating changes in the LV exercise reserve. The response of the systolic blood pressure to exercise may be an additional predictive factor for postoperative resting LV performance in patients with AR.

Adult↗