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Biomedical subjects

U Niklasson

Publications and source records attributed to U Niklasson.

17 recordsLinked to original sources
PubMed2007

Myocardial ischaemia in patients with peripheral arterial disease.

AIM: To study the relation between myocardial ischemia assessed with different techniques in patients with peripheral arterial disease (PAD) in comparison with a matched control group. METHODS: Ninety-nine male patients with PAD and 94 age- and sex-matched control subjects without PAD or ischaemic heart disease performed a exercise treadmill test, dipyridamole Tc-99m sestamibi myocardial perfusion SPECT (MPS) (43 controls) and 48-h ambulatory ECG (AECG)-monitoring (43 controls). RESULTS: Thirteen of 99 patients had irreversible and 24 of 99 had reversible perfusion defects in MPS in comparison with 0 of 43 and six of 43 of control subjects respectively (P<0.01). Thirteen of 84 evaluable patients experienced a total of 36 episodes of ST-depression in AECG in comparison with two episodes in two of 42 control subjects (P = 0.07). Out of 13 patients with ST-depression episodes only three had reversible ischaemia in MPS. CONCLUSION: Most PAD patients with episodes of ST-segment depression have no reversible ischaemia as assessed with dipyridamole-stress MPS. Episodes of ST-segment depression may reflect types of myocardial ischaemia that are different from those detected by MPS.

Aged↗
PubMed2004

Office blood pressure underestimates ambulatory blood pressure in peripheral arterial disease in comparison to healthy controls.

Patients with peripheral arterial disease (PAD) constitute a subgroup of high-risk hypertensives, but controlled studies on 24-h blood pressure (BP) and diurnal variation of BP are lacking. This study was performed in order to test the hypothesis that office BP (OBP) may underestimate 24-h BP in PAD patients in comparison to a matched control group. In all, 98 male patients (mean age 68 years) with a history of intermittent claudication and an ankle/brachial index less than 0.9, and 94 controls matched for age but without PAD or ischaemic heart disease performed 24-h recordings of ambulatory BP. A total of 59 patients had a history of hypertension and 69 were on treatment with BP-lowering drugs as compared to 17 and 23 of the control subjects, respectively. Office as well as 24-h systolic BP (SBP) were higher in patients as compared to controls (151 +/- 22 vs 140 +/- 20 mmHg, P < 0.001 and 142 +/- 14 vs 133 +/- 15 mmHg, P < 0.001, respectively), but did not differ with regard to diastolic BP. In an analysis of covariance with the continuous factors age, office SBP and the categorical factor antihypertensive treatment, 24-h SBP was higher in PAD patients compared to controls (P < 0.05). The difference between office and night SBP was lower in PAD patients with antihypertensive treatment compared to controls (P = 0.01). In conclusion, Male patients with PAD had higher systolic but not diastolic BP than age-matched control subjects. In PAD patients, 24-h SBP was higher than expected from OBP compared to controls. Night SBP was higher only in patients with antihypertensive treatment. In PAD patients, especially when on antihypertensive treatment, the severity of hypertension may be underestimated when based on OBP only.

Aged↗
PubMed2002

Myocardial contrast echocardiography yields best accuracy using quantitative analysis of digital data from pulse inversion technique: comparison with second harmonic imaging and harmonic power Doppler during simultaneous dipyridamole stress SPECT studies.

AIMS: This prospective study assesses the (1) feasibility of quantifying ultrasound myocardial perfusion studies based on the densitometric analysis of digital data and the (2) comparison of pulse inversion, second harmonic and harmonic power Doppler modalities with SPECT. METHODS AND RESULTS: Twenty-three patients with suspected ischaemic heart disease had i.v. injections of Tc-Sestamibi and Optison during a dipyridamole stress test for echocardiography in pulse inversion, second harmonic and harmonic power Doppler mode. Analysis was (a) visual by scoring and (b) quantitative by densitometry of digital data for background subtracted myocardial opacification (a.u.) and normalized contrast effect (%). In the nine control patients, myocardial opacification at stress was greater (P< or =0.002) than in the pathologic group (5. +/- 3.3 vs 2.6 +/- 2.5 a.u. in pulse inversion, 5.4 +/- 2.1 vs 2.4 +/- 1.8 in second harmonic and 7.1 +/- 3.7 vs 4.9 +/- 3.7 a.u. in harmonic power Doppler). In the pathologic group, normalized contrast effect decreased significantly during stress (23.7 +/- 18.8 to 11.3 +/- 10.8%, P<0.003) only in pulse inversion. Kappa values for patient based diagnostic agreement with SPECT were 0.75 by pulse inversion, 0.62 by second harmonic and 0.52 by harmonic power Doppler for quantitative analysis, and 0.51, 0.37 and 0.35 respectively, for visual assessment. CONCLUSION: Myocardial contrast echocardiography should be analysed using densitometry of digital data. The new technique pulse inversion demonstrates best agreement with SPECT data.

Albumins↗
PubMed2001

Episodes of ST-segment depression is related to changes in ambulatory blood pressure and heart rate in intermittent claudication.

OBJECTIVE: To study the prevalence and circadian distribution of ischaemic ST-segment depression detected with ambulatory electrocardiographic monitoring (AECG) in patients with intermittent claudication (IC) as well as to study ambulatory blood pressure (ABP) and the relation of ischaemic episodes to variations in ABP and heart rate. DESIGN: A total of 40 patients with a history of IC and an ankle/brachial-index (ABI) <0.9 performed: (i) 24-h AECG recordings, (ii) simultaneous 24 h recordings of ABP every 15 min (Spacelabs 90207), (iii) an exercise treadmill test (ETT). An ischaemic episode was defined as a transient ischaemic ST-segment deviation > or =1 mm lasting >1 min. Eleven patients were excluded from ECG analysis because of uninterpretable ECG caused by treatment with digoxin or technical problems. RESULTS: Out of 29 patients, eight experienced a total of 15 episodes of ST-depression on AECG. The mean duration was 21+/-31 min. The majority of episodes (11 of 15) occurred between 6 and 12 a.m. In eight patients with ST-segment depression three had a history of ischaemic heart disease (IHD), four were hypertensives and four had signs of myocardial ischaemia on ETT. There were no significant differences between patients with and without ST-segment depression in ABP, walking performance or ABI. During ST-depression episodes systolic and diastolic blood pressure and heart rate were higher than day mean values; 178+/-41 vs. 166+/-30 mmHg (P= 0.09); 96+/-9 vs. 90+/-4 mmHg (P = 0.01) and 103+/-9 vs. 87+/-5 beats min(-1) (P < 0.01). CONCLUSION: Silent myocardial ischemia occurred in about a third of patients with IC. Episodes of ischaemia were associated with an increased ABP and heart rate. Whether treatment of high blood pressure may reduce silent ischaemia and if this favourably influences outcome is a matter of further research.

Aged↗
PubMed2001

Thallium-201 myocardial imaging at rest in male orienteers and other endurance athletes.

During the period 1979 to 1992, 16 sudden unexpected cardiac deaths were known to have occurred in young Swedish orienteers. Autopsy indicated myocarditis to be the most frequent finding, most often combined with extensive myocardial fibrosis. The aim of the present investigation was to explore whether young male orienteers show a higher frequency than other young elite endurance athletes (controls) in the occurrence of Thallium-201 myocardial perfusion defects at rest, suggestive of fibrosis evoked by myocarditis. Thallium-201 perfusion abnormalities at rest were more frequently found in the controls than in the orienteers (26% vs. 12%, p=0.03). Uneven Tl-201 perfusion was associated with left ventricular mass (r=0.32, r=0.24, p<0.01, p=0.02) and body weight (r=0.30, r=0.31, p<0.01, p=0.03) in orienteers and controls, respectively. Echocardiographic left ventricular wall motion abnormalities were found in 11 athletes (9 orienteers and 2 controls) but only two displayed an abnormal Thallium-201 perfusion scan at rest. Perfusion abnormalities at rest did not occur more frequently in the orienteers but were commonly found in both groups of apparently healthy athletes making it futile to discern abnormals from normals. Thallium-201 perfusion aberrations were not associated with left ventricular wall motion abnormalities obtained by echocardiography.

Adult↗
PubMed2000

[Contrast echocardiography].

The intravenous application of an ultrasound contrast agent induces enhanced display of blood in all its pathways. Within cardiology, this principle is mainly utilized for signal enhancement of color Doppler and spectral Doppler in order to improve quantification of congenital and acquired valvular lesions and also for improved endocardial delineation during stress tests and in the evaluation of LV function. The new domaine of myocardial perfusion imaging by contrast echocardiography, however, needed profound technical developments before realization of the clinical potential could even be conceived. These are based on the complex reactions of microbubbbles in the acoustic field in order to allow the sensitive and bubble specific display of intramyocardial contrast effects. The presently available acquisition techniques, second harmonic imaging and harmonic power Doppler, demonstrate significant improvements if compared to traditional fundamental 2-d echocardiography; however, they are still subjected to important limitations. There are many anatomical, physiological, and technical reasons for insufficient display of intramyocardial microbubbles, the most important one being attenuation. It is hoped that the most recently developed imaging modality, pulse inversion technique, allows the necessary diagnostic accuracy and reproducibility in myocardial perfusion imaging.

Contrast Media↗
PubMed2000

Endoscopic transthoracic sympathicotomy affects the autonomic modulation of heart rate in patients with palmar hyperhidrosis.

BACKGROUND: Palmar hyperhidrosis has been associated with an increased activity of the sympathetic nervous system. The objective of this study was to assess the immediate and long-term effects of endoscopic transthoracic sympathicotomy on the autonomic modulation of the heart rate in patients with palmar hyperhidrosis. METHODS: Power spectrum analysis of heart rate variability in the lying position and after passive tilt to the upright position was performed in thirteen patients the day before and after sympathicotomy. A follow-up recording was performed in ten patients approximately six months later. Recordings from 26 healthy subjects were used as a reference group. FINDINGS: The patients had a tendency to higher power of the low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF; above 0.15 Hz) components than controls in the upright position. After sympathicotomy LF power was reduced, but HF power was unchanged. At follow-up LF power remained at a lower level, but now HF power was reduced. INTERPRETATION: Patients with palmar hyperhidrosis have a sympathetic overactivity but also a compensatory high parasympathetic activity. Sympathicotomy results in an initial sympathovagal imbalance with a parasympathetic predominance, which is restored on a long-term basis.

Adult↗
PubMed2000

Autonomic cardiovascular regulation in patients with obstructive sleep apnoea: a study based on spectral analysis of heart rate variability.

The aim of this study was to assess the function of the autonomic nervous system in patients with obstructive sleep apnoea syndrome (OSAS). The study was designed as a cross-sectional case-control study. Fifty-one patients were included, and the findings were compared with those in 66 controls. Spectral analysis of heart rate variability (HRV) during supine rest, during controlled breathing and after tilting was performed in each patient and control case. The patients performed overnight sleep recordings the night before the HRV recordings. Individuals with an apnoea-hypopnoea index (AHI) above 20 were regarded as OSAS patients and those with AHI lower than 20 as snorers. Differences in HRV and blood pressure between patients and controls were analysed by multiple linear regression with age, body mass index and sex as independent variables. During free and controlled breathing there was a significant decrease in indices reflecting vagal modulation, indicating parasympathetic dysfunction in OSAS patients compared with controls. The mid-frequency component was also significantly reduced in OSAS patients after tilting but not in the lying position. This may be related to the parasympathetic dysfunction, but could also indicate a decreased sympathetic reserve capacity. We found no significant relation between AHI and indices of vagal modulation in the patient group. Our findings show an autonomic dysfunction in patients with OSAS. The dysfunction involves the parasympathetic system, and may be related to the increased cardiovascular mortality and malignant arrhythmia described in OSAS.

Adult↗
PubMed1999

Wall motion abnormalities in male elite orienteers are aggravated by exercise.

During the period 1979-92, 16 (15 men and one woman) sudden unexpected cardiac deaths occurred among young Swedish orienteers. This finding indicated a sharp increase in the death rate of orienteers, and necropsy demonstrated that myocarditis was a common histopathological finding. Therefore, an extensive non-invasive cardiac investigation was performed. A total of 59 male élite orienteers (mean age 23 years) and 36 cross-country skiers and middle-distance runners (mean age 22 years), serving as controls, were examined by both echocardiography at rest and radionuclide ventriculography at rest and during exercise. Wall motion abnormalities were found in eight orienteers using echocardiography. The purpose of this study was to examine whether the group of orienteers with wall motion abnormalities found using echocardiography had a smaller increase in ejection fraction from rest to exercise using radionuclide ventriculography than the rest of the orienteers and the controls, indicating an aggravation of the wall motion abnormalities during exercise. There were no significant differences in the ejection fraction at rest between the groups. In the orienteers with wall motion abnormalities (group 1), 62% (five out of eight) had less than a 0.05 unit increase in left ventricular ejection fraction compared with 27% (14 out of 51) of the remaining orienteers (group 2) and 19% (7 out of 36) of the controls (group 3). A comparison of athletes in group 1 with those in groups 2 and 3 combined revealed a statistically significant difference (P < 0.05). The divergent response in left ventricular ejection fraction during exercise suggests an aggravation of the wall motion abnormalities with exercise. Both the echocardiographic and the radionuclide ventriculographic findings indicate that the orienteers in group 1 had concealed left ventricular damage.

Adolescent↗
PubMed1993

Heart-rate variation: what are we measuring?

Many methods have been proposed during the last two decades for the assessment of autonomic nervous system function by quantification of the heart-rate variation (HRV). Relatively little has been written about the HRV in relation to physiological models of the heart-rate regulation. The integral pulse frequency model (IPFM) is a simple model that describes the genesis of heartbeats under the influence of the autonomic nervous system. By comparing simulated HRV data generated with the IPFM model with data from healthy volunteers we found similarities indicating that the model accurately reflects real data. Furthermore, we found a considerable difference between HRV measurements based on beat-by-beat heart-rate and measurements based on the heartbeat interval. Our results suggest that the commonly used electrocardiographic RR interval representation of heart-rate variation might possess an inherent nonlinear, mean heart-rate-dependent property indicating that analysis directly based on RR intervals can give biased results with respect to the underlying autonomic activity. The conclusions embrace all measurements of variation that are directly based on RR intervals including simple indices as well as higher-level quantification such as spectral analysis.

Adult↗
PubMed1993

Effects of cold pressor test on circulating atrial natriuretic peptide 99-126 (ANP) in patients with Raynaud's phenomenon and influence of treatment with magnesium sulphate and nifedipine.

The effect of a standardized cold pressure test (CPT) on the venous concentration of immunoreactive atrial natriuretic peptide (irANP) was studied in 12 females with primary Raynaud's phenomenon (PRP) and 12 female age-matched controls. The test was performed at the end of three stages. During the first stage no medication was given. During the second stage a magnesium infusion was given. After fourteen days of medication with a calcium antagonist (Nifedipine) the third stage of the study was performed. The venous irANP increased significantly (P < 0.05) 10 min after the start of the CPT both in the PRP group and in the control group (136 +/- 39 to 159 +/- 54 and 153 +/- 45 to 179 +/- 40 pg ml-1, given as mean and SD). Baseline irANP did not change in the PRP group after treatment with magnesium or nifedipine. In the control group nifedipine treatment significantly (P < 0.01) lowered venous irANP compared to the no treatment or magnesium sulphate infusion stages (128 +/- 31 vs. 153 +/- 45 and 160 +/- 41 pg ml-1). After the CPT in both PRP group and control group the venous irANP did not increase either during magnesium sulphate infusion or nifedipine treatment. In conclusion the study has demonstrated that a standardized CPT results in a delayed increase in irANP in venous plasma and that magnesium sulphate infusion and nifedipine treatment prevent this increase. Furthermore, our data do not suggest a role for irANP in the symptomatology of primary Raynaud's phenomenon.

Adult↗
PubMed1990

Assessment of autonomic nerve function in myotonic dystrophy.

The function of the autonomic nervous system was studied in 23 patients with myotonic dystrophy, from a defined population in northern Sweden with an extremely high prevalence of this disease. Heart rate variability tests showed only minor signs of parasympathetic dysfunction. Blood pressure and plasma noradrenaline measurements in recumbent and upright positions showed no signs of sympathetic neuropathy. Increased plasma levels of noradrenaline was an unexpected finding. Our study does not support the hypothesis that cardiac arrhythmias, orthostatic hypotension, gastrointestinal motility disturbances and urinary bladder dysfunction in myotonic dystrophy are caused by autonomic neuropathy, and we believe that these symptoms should rather be ascribed to a defective function of the target organs.

Adolescent↗
PubMed1989

Continuous and stepwise cystometry through suprapubic catheters--effect of infusion pattern and infusion rate on the cystometrogram of the normal human bladder.

Continuous cystometry at two filling rates (50 and 100 ml min-1) and stepwise cystometry (successive rapid volume infusions followed by bladder wall relaxation) were performed in 12 healthy subjects. Suprapubic catheters were used for infusion and recording of perivesical and intravesical pressures. The continuous cystometrograms obtained at filling rates of 50 and 100 ml min-1, respectively, did not differ with respect to desire to void, transmural pressure increase or bladder capacity. Stepwise cystometry allowed the bladders to be filled to a slightly larger volume than during continuous cystometry, but with comparatively lower transmural pressures only at very large distension of the bladder. There was considerable inter-individual variation in transmural pressure at both continuous and stepwise cystometry. Stepwise cystometry did not appear to provide any important additional information about pressure-volume relationship in the normal human bladder than could be obtained at routine clinical cystometry.

Administration, Intravesical↗
PubMed1989

Autonomic neuropathy in familial amyloidotic polyneuropathy. A clinical study based on heart rate variability.

Familial amyloidotic polyneuropathy (FAP) is characterized by both sensimotor and autonomic dysfunction. Autonomic disturbance involving the gastrointestinal tract, the urinary bladder, the cardiac conduction system, and the peripheral circulation has been described. In this study simple, non-invasive tests of autonomic function based on heart rate variability were applied to 12 patients with FAP and 12 healthy volunteers. The heart rate variation during normal breathing, deep breathing and during tilt from recumbent to standing position was measured. All tests showed significantly less heart rate variation in patients than in controls and the heart rate variation decreased with increasing severity of neurological disability, but the small number of patients in our study does not allow any further comparison between subgroups. Our study thus indicates impaired cardiovascular autonomic function in patients with FAP and we believe that these findings might also be of importance in other forms of systemic amyloidosis.

Adult↗