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Biomedical subjects

F Pedersen

Publications and source records attributed to F Pedersen.

At least 37 records · Page 2Linked to original sources
PubMed1991

Prevalence and significance of an abnormal exercise ECG in asymptomatic males. Outcome of thallium myocardial scintigraphy.

During a 3-year period 2500 asymptomatic male aviators were screened routinely for coronary artery disease by maximal bicycle exercise testing. In 55 cases (2.1%) the exercise ECG was abnormal (40 subjects exhibited ST depression, 14 ventricular ectopic activity and in one subject both abnormalities were observed). Further non-invasive studies (Thallium scintigraphy, echocardiography and ambulatory ECG monitoring for arrhythmias) identified nine out of the 55 aviators (16%, 95% CL = 7-26%) with an abnormal exercise test as having cardiac disease. We conclude that standard exercise ECG by itself is a poor predictor of coronary artery disease in asymptomatic subjects because of too many false-positives when the pre-test likelihood of disease is low. Therefore, exercise electrocardiography cannot be recommended as the single routine screening test for coronary artery disease in such individuals.

Adult↗
PubMed1991

Continuous oral N-acetylcysteine treatment and development of nitrate tolerance in patients with stable angina pectoris.

The presence of sulfhydryl (SH) groups appears to be fundamental to nitrate-induced vasodilation and N-acetylcysteine (NAC), a sulfhydryl (SH)-donor substance, potentiates hemodynamic responsiveness to nitrates. We investigated the effect of simultaneous administration of NAC and isosorbide dinitrate (ISDN) on development of nitrate tolerance. In a double-blind, randomized, placebo-controlled cross-over study, seven patients with stable angina pectoris were treated for two 8-day periods with ISDN (40 mg four times daily, q.i.d.) together with NAC (controlled release 600 mg q.i.d.) or matching placebo. Bicycle exercise tests were performed before treatment was started, 1 h after treatment was started, and at day 8. After 8-day treatment with ISDN + placebo, responses determined by exercise testing were diminished as compared with responses obtained during acute therapy and did not differ from baseline values, suggesting development of tolerance to ISDN. During treatment with ISDN + NAC, time to 1-mm ST depression was significantly prolonged (441 +/- 44 vs. 381 +/- 40 s, mean +/- SEM) and total ST segment depression significantly reduced (1.9 +/- 0.7 vs. 3.5 +/- 0.8 mm) as compared with baseline values. The reduction in ST segment depression was significantly more pronounced during ISDN + NAC (46%) as compared with ISDN + placebo (23%). Although exercise time and time to angina pectoris were unaffected. NAC augmented the antiischemic effects of ISDN as assessed by ECG. This finding may suggest that development of nitrate tolerance is modified by chronic oral high-dose NAC administration.

Acetylcysteine↗
PubMed1991

High-frequency amplification with ITC-HA and BTE-HA. A comparative investigation.

The purpose of the present investigation was to evaluate the magnitude of selective high-frequency amplification obtained by an in-the-canal hearing aid (ITC-HA), and to compare it with that obtained with a conventional behind-the-ear hearing aid (BTE-HA) with an open mould. 22 subjects (20 males, 2 females) at a median age of 66 years (range 46-84) were included in the investigation. All suffered from a bilateral high-frequency hearing loss with normal or near-normal hearing thresholds at 0.5 and 1 kHz. Insertion gain measurements demonstrated that the ITC-HA gives a significantly higher amplification in the high-frequency area, when compared with the BTE-HA, though neither of the hearing aids amplified as much as indicated by the POGO strategy. Although a better amplification in the high-frequency area was obtained with the ITC-HA, it did not result in significantly better speech recognition when compared with the BTE-HA. At the hearing aid fitting, all subjects preferred the ITC-HA, and after an observation period of one year, 68% of those fitted used the aid continuously. Based on the investigation it is concluded that hearing-impaired persons can be fitted with an ITC-HA, even if they have pronounced high-frequency hearing loss, and that this type of aid is preferred by the hearing-impaired to the conventional BTE-HA.

Aged↗
PubMed1991

Microvascular right-to-left pulmonary shunt demonstrated by a radionuclide method.

A 37-yr-old man with angiolymphoid hyperplasia (Kimura's syndrome), who had been treated unsuccessfully for suspected asthma, was investigated due to a decrease in arterial oxygen saturation (86%). Right heart catheterization and angiography of the pulmonary artery failed to demonstrate any right-to-left shunts. However, simultaneous scintigraphy over the lungs, kidneys, and head after injection of 150 MBq technetium-99m-labeled macroaggregated albumin i.v. and inhalation of 150 MBq krypton-81m demonstrated a right-to-left shunt in the lungs probably caused by precapillary pulmonary arteriovenous shunts.

Adult↗
PubMed1990

[Use of fibrinolytics in the treatment of acute myocardial infarction in Denmark. A questionnaire study].

Questionnaires were sent to all Danish departments admitting patients with acute myocardial infarction (AMI) in order to investigate the attitudes of the departments to thrombolytic therapy in AMI. Two questionnaires were used: one with few questions which was answered by all 68 departments, and a more comprehensive questionnaire which was answered by 51 departments. The study shows that thrombolytic therapy now is use in all departments as opposed to 25% two years ago. In connection with introduction of thrombolytic therapy scientific studies are performed in 75% of the departments. In all departments, streptokinase (SK) is the drug of first choice and recombinant tissue plasminogen activator (rt-PA) is used in 2/3 of the departments in cases where SK-antibodies are suspected.

Denmark↗
PubMed1990

ECG and enzymatic indicators of therapeutic success after intravenous streptokinase for acute myocardial infarction.

Thrombolytic therapy has been documented to result in reperfusion of jeopardized myocardium and reduction in the size of the acute myocardial infarction (AMI). The effect of intravenous streptokinase on a creatine kinase-MB (CK-MB) reperfusion index and an ECG estimate of myocardial salvage was therefore studied in 65 patients with a first AMI, randomized to treatment with streptokinase (n = 33) or placebo (control group, n = 32). Reperfusion was defined as a CK-MB appearance rate constant (k1) greater than 0.185. The final AMI size was first predicted from the admission standard ECG by previously developed formulas based on ST segment elevation. The final AMI size was estimated from the QRS score on the predischarge ECG. Myocardial salvage was defined as a greater than or equal to 20% decrease from predicted to final AMI size. The k1 value in the control group was significantly lower than that in the streptokinase group (median 0.157 versus 0.328; p = 0.0001). Accordingly the reperfusion rate was higher in the streptokinase group than in the control group (88% versus 34%; p = 0.0002). The difference in AMI size (final-predicted) was significantly greater in the streptokinase group than in the control group (median -7% versus +1%; p = 0.0001). Myocardial salvage occurred in 60% and 19%, respectively (p = 0.004). A significant correlation was found between CK-MB reperfusion and ECG salvage: 19 of 20 streptokinase-treated patients with salvage also had reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Creatine Kinase↗
PubMed1990

Effect of intravenous streptokinase on the relation between initial ST-predicted size and final QRS-estimated size of acute myocardial infarcts.

Thrombolytic therapy has been documented to reduce acute myocardial infarct size. The previously established relation between initial ST segment elevation and final electrocardiographic (ECG) myocardial infarct size in patients without coronary reperfusion might therefore be altered by thrombolytic therapy. The effect of intravenous streptokinase on this relation was therefore studied in 73 patients with initial acute myocardial infarction who had participated in the Second International Study of Infarct Survival (ISIS-2). Patients who received streptokinase were considered as one group and patients who did not receive streptokinase as a control group. Final myocardial infarct size, which was estimated from the QRS score, was predicted from the admission standard ECG by previously developed formulas based on ST segment elevation. In the 40 control patients there was no change from ST-predicted to final QRS-estimated infarct size (median 17.7% versus 18.3%; p = NS). In the 33 patients in the streptokinase group, there was a highly significant decrease from predicted to final myocardial infarct size (median 21.9% versus 16.2%; p less than 0.0002). This decrease was found for both anterior (median 23.7% versus 19.5%; p less than 0.03) and inferior (median 21.9% versus 12.0%; p = 0.001) infarct locations. Multiple regression analysis adjusting for differences in predicted infarct size confirmed the significance of streptokinase on the difference in infarct size (p = 0.006). Based on the variability of the percent change from predicted to final infarct size in the control group, a threshold decrease greater than or equal to 20% is required for identification of salvage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin↗
PubMed1990

Effects of acupuncture in moderate, stable angina pectoris: a controlled study.

In order to evaluate the effects of acupuncture in moderate, stable angina pectoris, 49 patients were randomized to either genuine or sham acupuncture. In sham acupuncture needles were inserted into points within the same spinal segment as in genuine acupuncture, but outside the Chinese meridian system. The effect was evaluated from exercise tests, anginal attack rate and nitroglycerin consumption. There were no significant differences between the effects of genuine and sham acupuncture either on exercise test variables or on subjective variables. In patients receiving genuine acupuncture there was a significant increase in exercise tolerance (median 9%) and in delay of onset to pain (median 10%). No significant changes were observed in patients receiving sham acupuncture. Within both groups there was a median reduction of 50% in anginal attack rate and nitroglycerin consumption, and there was no significant difference between the results achieved in the two groups. It is concluded that with the present design it was not possible to demonstrate any significant differences between the effect of genuine and sham acupuncture.

Acupuncture Therapy↗
PubMed1989

[Reduction of mortality in acute myocardial infarction with streptokinase and aspirin therapy. Results of ISIS-2].

This investigation includes 17,187 patients in 417 hospitals in 16 countries admitted within 24 hours of the commencement of symptoms of acute myocardial infarction (AMI). The patients were allotted at random to the following treatments 1) intravenous infusion of 1.5 million International Units streptokinase (SK) during one hour, 2) 160 mg acetyl salicylic acid (ASA) daily for 30 days, 3) both SK and ASA and 4) placebo treatment only. The five-week cardiovascular mortality was reduced by 25% following infusion of streptokinase from 12.0% to 9.2% and by 23% during ASA treatment from 11.8% to 9.4%. The combination of SK and ASA resulted in 42% reduction in the cardiovascular mortality after five weeks compared with the placebo. The effect of SK was greatest if treatment was instituted within six hours but effects were obtained after all of the first 24 hours. The preliminary results show that the reduction in mortality obtained by both SK and ASA appears to continue during the subsequent one to two years. SK treatment resulted in haemorrhage requiring treatment in 0.5% as compared with 0.2% in the placebo group, more cases of proved cerebral haemorrhage, 0.1% as compared with 0.0%, but fewer cases of cerebral apoplexy, 0.7% as compared with 0.8%. It is concluded that thrombolysis with SK combined with prophylaxis of repeated thrombosis with ASA is the indicated treatment in cases of AMI and less than 6-24 hours duration.

Aged↗
PubMed1989

[Bone scintigraphy in patients with hip joint prostheses. Use of bone scintigraphy in hip pain after total hip replacement].

A retrospective investigation was undertaken to assess the value of bone scintigraphy with 99mtechnetium methylene-diphosphonate in patients referred with hip pain after total hip replacement. The material comprized 68 patients with a total of 68 prostheses. This review revealed that 10/25 of the patients with pathological scintigrams and 6/28 of the patients with normal scintigrams were submitted to replacement of the prostheses. In the way in which it was carried out and interpreted in this department, scintigraphy was of limited value in selection of the patients who required replacement of the prostheses.

Aged↗
PubMed1989

Elevated pain threshold in patients with effort-induced angina pectoris and asymptomatic myocardial ischemia during exercise test.

The purpose of the present study was to analyze the prevalence of asymptomatic (silent) myocardial ischemia during exercise testing among patients with effort-induced angina pectoris, and further, to compare the pain threshold of patients with symptomatic and asymptomatic myocardial ischemia. A group of 26 patients comprised the study. In half of the patients myocardial ischemia during the exercise testing was silent and in one half it was symptomatic. Asymptomatic myocardial ischemia was defined as an asymptomatic ST-segment depression greater than or equal to 0.1 mV, lasting longer than 60 s during an exercise test. In patients with asymptomatic ischemia the pain thresholds both on toe and finger were significantly higher than in patients with symptomatic ischemia: mean values were 10.1 versus 4.9 mA on the toes, p less than 0.025, and 8.4 versus 2.5 mA on the fingers, p less than 0.01. We conclude that asymptomatic myocardial ischemia during exercise test is seen often in patients with angina pectoris and that this may be due to an increased pain threshold.

Aged↗
PubMed1989

Echocardiography and cerebral computed tomography in chronic atrial fibrillation.

Chronic atrial fibrillation (CAF) may be complicated by asymptomatic small silent cerebral infarctions as well as by stroke. The echocardiographic findings in 29 patients with CAF and 29 controls in sinus rhythm are presented. The cerebral computed tomography (CT) findings in these patients were previously published and significantly more small low-density lesions, probably reflecting previous infarctions, were found in patients with CAF than in controls. The aim of the present study was to evaluate if patients with such cerebral lesions had characteristic echocardiographic abnormalities with special reference to patients with CAF. No significant differences could be detected between the groups with and without cerebral lesions regarding the occurrence of valvular heart disease, left ventricular dysfunction, end-diastolic diameter of the left ventricle, left atrial dimension and left ventricular fractional shortening. Only seven patients with CAF (24%) compared with 21 in sinus rhythm (72%) had normal echocardiograms (P less than 0.001). In conclusion, echocardiography gave no guidance to why some patients developed cerebral low-density areas on CT.

Aged↗
PubMed1989

Cerebral computed tomography in paroxysmal atrial fibrillation.

Atrial fibrillation (AF) is associated with an increased risk of stroke. In patients with chronic AF, without clinically known cerebrovascular disease, computed tomography (CT) has revealed a high frequency of abnormal low-density areas suggesting old asymptomatic infarcts. To investigate the frequency of such lesions in paroxysmal AF, 30 patients with paroxysmal AF and 30 controls matched in sinus rhythm, without history of cerebrovascular disease, were CT scanned. Four patients with paroxysmal AF (13%) and 3 controls (10%) had abnormal CT scans with areas of low density with sharp demarcation from surrounding tissue. The abnormal areas probably reflected small, clinically silent infarcts. There were no differences between paroxysmal AF and controls in number and size of abnormal areas with apparent tissue loss. In contrast to chronic AF, the risk of such lesions in paroxysmal AF does not seem to be increased compared with matched sinus rhythm controls. This is in agreement with the clinical experience of a low risk of stroke in paroxysmal AF.

Adult↗
PubMed1988

Serum magnesium, calcium, phosphate and PTH following long-term beta-blockade in ischaemic heart disease.

In 40 patients with ischaemic heart disease the serum levels of magnesium, parathyroid hormone (PTH), phosphate, calcium, and ionized calcium remained unchanged and within normal limits following treatment for 12 months with alprenolol (n = 20) or placebo (n = 20). No changes occurred during a 2 week withdrawal period. The clinical implication is that the non-cardioselective betablocker alprenolol can be given to patients with ischaemic heart disease without the risk of inducing potentially cardiotoxic disturbances in serum magnesium and serum calcium levels. Whether this applies to cardioselective beta-blockers remains to be established.

Adrenergic beta-Antagonists↗