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Biomedical subjects

P F Høilund-Carlsen

Publications and source records attributed to P F Høilund-Carlsen.

At least 19 recordsLinked to original sources
PubMed2006

External dose rates in radioiodine treatment of benign goitre: estimation versus direct measurement.

OBJECTIVE: According to European recommendations, the external dose rate (ED) in radioiodine-treated goitre patients can be determined by estimating from calculation of the residual activity (RA) in the patient based on radioiodine uptake measurements or by measuring ED directly. In the European guidelines, "Radiation Protection 97", it is assumed that an RA of 600 MBq (131)I causes an ED of 30 microSv/h at a distance of 1 m. This implies a slope of 0.05 microSv/h/MBq for the ratio ED/RA relationship, but, theoretically, this ratio is higher, at 0.07, a difference that is due to measurement in air versus in a scattering medium. We sought to investigate what the true ratio might be. MATERIAL AND METHODS: Sixty-six patients scheduled for radioiodine treatment of benign goitre (mean size 102 mL, range 20-440), who received (131)I orally (mean 984 MBq, range 173-3700) were examined. After 24 h and 96 h iodine uptake percentage we examined 7269 patients scheduled for radioiodine treatment of benign goitre (mean size 1042 mL, range 20-440) who received (131)I orally (mean 101,100 MBq, range 180-3700). After 24 h and 96 h, the iodine uptake was determined, RA calculated and ED measured using a hand-held dosimeter. RESULTS: At 24 and 96 h, we observed a slope ratio of 0.103 microSv/h/MBq (95 % CI: 0.09564-0.111) and 0.101 microSv/h/MBq (95 % CI: 0.0915-0.11107), respectively, for the ED/RA relationship. None of the confidence intervals included the value 0.05 microSv/h/MBq, reflecting that the observed slopes differed significantly from the expected slope (p < 0.001). Consequently, an RA of 600 MBq typically causes an ED of 60 and not 30 microSv/h, and therefore dose rates based on radioiodine uptake measurements and established assumptions were only about half as high as the directly measured values. We noticed that with an RA roughly below 450 MBq, the anticipated slope of 0.05 microSv/h/MBq is within the prediction interval of our claimed ratio, therefore we cannot rebut the anticipated slope for lower doses. CONCLUSIONS: Dose-rate estimates based on radioiodine uptake measurements and established assumptions were only about half as high as the directly measured values in patients receiving doses higher than the widely accepted limits for outpatient treatment. This finding may have substantial implications for us, in that it makes a considerable difference whether the radiation precautions are taken to limit doses to the patient's surroundings and for deciding if a patient may or may not be regarded as an outpatient, as well as for the safe discharge of an inpatient from hospital.

Administration, Oral↗
PubMed2004

Effects of oxytocin in normal man during low and high sodium diets.

AIM: We tested the hypothesis that oxytocin in normal man causes natriuresis by means of nitric oxide and/or atrial natriuretic peptide. METHODS: Normal male subjects were investigated after 4 days of sodium controlled diets (30 mmol sodium chloride day(-1), n = 8 or 230 mmol sodium chloride day(-1), n = 6). Oxytocin was infused intravenously (1 pmol kg(-1) min(-1) for 240 min). RESULTS: Mean arterial blood pressure, heart rate and glomerular filtration rate by clearance of chromium-labelled ethylenediaminetetraacetate remained stable. Plasma oxytocin increased from 2 to 3 pg mL(-1) to around 50 pg mL(-1). Oxytocin decreased urine flow (4.2 +/- 0.2--0.75 +/- 0.11 and 4.6 +/- 1.3-1.4 +/- 0.6 mL min(-1), low- and high-salt diet, respectively). During low-salt conditions, oxytocin reduced sodium and potassium excretion (11 +/- 2--4 +/- 2 and 93 +/- 19--42 +/- 3 micromol min(-1), respectively). Plasma renin, angiotensin II, aldosterone and renal excretion of metabolites of nitric oxide (nitrate and nitrite) all decreased. Plasma atrial natriuretic peptide and cyclic guanosine monophosphate were unchanged. A similar pattern was obtained during high-salt conditions but in this case the antinatriuresis was not different from that occurring during the corresponding time control series. CONCLUSIONS: The data reject the hypothesis. In contrast, we found significant antinatriuretic, antikaliuretic and antidiuretic effects, which were not mediated by the renin-angiotensin-aldosterone system, atrial natriuretic peptide, systemic haemodynamics, or processes increasing urinary excretion of metabolites of nitric oxide. The natriuretic effect of oxytocin found in laboratory animals is species-specific.

Adult↗
PubMed2003

Mechanisms of acute natriuresis in normal humans on low sodium diet.

This study evaluates the relative importance of several mechanisms possibly involved in the natriuresis elicited by slow sodium loading, i.e. the renin-angiotensin-aldosterone system (RAAS), mean arterial blood pressure (MAP), glomerular filtration rate (GFR), atrial natriuretic peptide (ANP), oxytocin and nitric oxide (NO). Eight seated subjects on standardised sodium intake (30 mmol NaCl day(-1)) received isotonic saline intravenously (NaLoading: 20 micromol Na(+) kg(-1) min(-1) or approximately 11 ml min(-1) for 240 min). NaLoading did not change MAP or GFR (by clearance of (51)Cr-EDTA). Significant natriuresis occurred within 1 h (from 9 +/- 3 to 13 +/- 2 micromol min(-1)). A 6-fold increase was found during the last hour of infusion as plasma renin activity, angiotensin II (ANGII) and aldosterone decreased markedly. Sodium excretion continued to increase after NaLoading. During NaLoading, plasma renin activity and ANGII were linearly related (R = 0.997) as were ANGII and aldosterone (R = 0.999). The slopes were 0.40 pM ANGII (mi.u. renin activity)(-1) and 22 pM aldosterone (pM ANGII)(-1). Plasma ANP and oxytocin remained unchanged, as did the urinary excretion rates of cGMP and NO metabolites (NO(x)). In conclusion, sodium excretion may increase 7-fold without changes in MAP, GFR, plasma ANP, plasma oxytocin, and cGMP- and NO(x) excretion, but concomitant with marked decreases in circulating RAAS components. The immediate renal response to sodium excess appears to be fading of ANGII-mediated tubular sodium reabsorption. Subsequently the decrease in aldosterone may become important.

Adult↗
PubMed2001

[Myocardial scintigraphy and coronary arteriography in patients with known or suspected stable angina pectoris].

INTRODUCTION: Myocardial perfusion imaging (MPI) demonstrates regional hypoperfusion, whereas coronary angiography shows anatomical stenoses in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. MATERIALS AND METHODS: MPI was undertaken before angiography in 86 randomly selected patients with stable angina pectoris. RESULTS: Of 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single vessel and 34 with multivessel disease). With angiography as reference, the sensitivity and specificity of MPI in the detection of coronary artery disease were 88% and 93%, respectively. DISCUSSION: Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do not usually require invasive investigation and therapy. Reversible ischaemia and irreversible ischaemia with viable tissue call for coronary revascularisation.

Adult↗
PubMed2001

In-hospital heart failure, first-year ventricular dilatation and 10-year survival after acute myocardial infarction.

BACKGROUND: Little is known about the factors that determine long-term prognosis in patients who have survived the first year after acute myocardial infarction (AMI). AIMS: To study the influence of left and right ventricular (LV and RV) dilatation during the first year after AMI on subsequent 10-year survival in comparison with in-hospital heart failure and other established prognostic indices. METHODS: Radionuclide ventriculography was performed before the era of thrombolysis and post-infarction ACE-inhibition in 57 patients with AMI at hospital discharge and again 1 year later, and compared with survival the ensuing 10 years. RESULTS: After 1 year significant LV-dilatation (>20%) had occurred in 32 (56%) patients. One year after the re-investigation the mortality in these was 19% vs. 0% in patients without dilatation (P=0.02); after 5 years the difference was 38 vs. 12% (P=0.02), whereafter it declined and became insignificant at 10 years. Neither RV-dilatation, nor LVEF determined at discharge or at the 1-year reinvestigation influenced long-term survival. In contrast, clinical heart failure recorded during the hospital stay had a sustained negative influence on long-term survival. CONCLUSION: Progressive LV dilatation after discharge and clinical heart failure during the hospital stay are both determinants of late survival after AMI, whereas LV ejection fraction at hospital discharge or 1 year later has little, if any, effect on survival beyond 1-year post-AMI.

Adult↗
PubMed2001

In vivo secretory potential and the effect of combination therapy with octreotide and cabergoline in patients with clinically non-functioning pituitary adenomas.

The secretory capacity, in vivo, of clinically non-functioning pituitary adenomas may possibly predict tumour volume reduction during intensive medical therapy. Ten patients (mean (range) 53 years (26-73)) with clinically non-functioning macroadenomas, > or = 10 mm were studied. The secretory capacity of the adenomas was examined using basal, NaCl and TRH-stimulated LH, FSH and alpha-subunit levels. The effect on tumour volume of 6 months' therapy with the combination of a somatostatin analogue, octreotide 200 microg x 3/day and a dopamine-D2-agonist, cabergoline 0.5 mg x 1/day was studied. The basal LH, FSH and alpha-subunit levels were determined before and during 6 months' therapy with octreotide and cabergoline, and MR scans were used to evaluate tumour volume before and during this period of therapy. Octopus-perimetry was used to examine the visual fields. A reduction in tumour volume (mean +/- SEM (range); 30% +/- 4% (18-46%)) during 6 months of combination therapy with octreotide and cabergoline was recorded only in patients with in vivo secretory potential. Tumour volume was not reduced in four patients: in three of these patients it remained unchanged while in one patient it was observed to have increased (by 14%). Of the six patients with pretherapy secretory capacity, one displayed a very high basal level of alpha-subunit (74 microg/l) despite unmeasurable levels of LH and TSH, and an FSH-level of 1 IU/l. The other five patients presented paradoxical LH, FSH and/or alpha-subunit responses to TRH. A reduction in basal levels of LH, FSH and/or alpha-subunit was observed in all six patients, and the maximum reduction of at least one of the hormonal levels was 66% +/- 7% (50-98%). The basal levels of LH, FSH and alpha-subunit in the 10 patients were (mean +/- SEM (range)), 3.0 IU/l +/- 1.0 (0.0-7.4), 12.7 IU/l +/- 5.0 (0.0-39.0) and 9.0 IU/l +/- 7.0 (0.2-74.0). During six months of therapy with octreotide and cabergoline, the basal levels of LH, FSH and alpha-subunit were reduced by > or = 50% in seven patients - including the six patients with in vivo secretion prior to therapy. No new visual field defects were detected during therapy and no deterioration of existing visual field defects was recorded. The medical therapy was well tolerated. The in vivo basal and TRH-stimulated secretory capacity of LH, FSH and alpha-subunit predicted tumour reduction following intensive medical therapy in all of our patients with non-functioning pituitary adenomas.

Adenoma↗
PubMed2001

Myocardial perfusion imaging and coronary angiography in patients with known or suspected stable angina pectoris.

INTRODUCTION: The patho-physiological cause of angina pectoris is myocardial ischaemia, which can be objectified by myocardial perfusion imaging (MPI). METHODOLOGY: MPI was undertaken prior to coronary angiography (CAG) in 86 randomly selected patients with known or suspected stable angina pectoris. RESULTS: Among 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single and 34 with multi vessel disease). Using angiography as a reference, the sensitivity and specificity of MPI in detecting coronary artery disease was 88% and 93%, respectively. DISCUSSION: MPI demonstrates regional hypoperfusion whereas CAG depicts anatomical stenosis in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. The functional significance of coronary artery lesions is, however, variable and MPI can demonstrate normal myocardial perfusion in the presence of moderate lesions. MPI exhibited a high sensitivity and specificity regarding significant lesions. More than one third of the subjects had a normal MPI and a normal CAG. Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do usually not require further invasive investigation or therapy. Reversible ischaemia and irreversible ischaemia with demonstration of viable tissue call for coronary revascularisation.

Adult↗
PubMed2000

[Invasive treatment of angina pectoris. A need for re-thinking?].

Evaluation and treatment of stable angina pectoris is based on invasive diagnostic and therapeutic procedures focused on identification and treatment of coronary artery stenoses, instead of myocardial ischaemia which is considered the cause of symptoms. Thus, coronary angiography should possibly be preceded routinely by myocardial perfusion imaging, which can provide the diagnosis of ischaemia and determine if the patient will benefit from invasive therapy. As a consequence, treatment of patients without ischaemia and patients with ischaemia so serious that invasive therapy is futile might be avoided. It is unknown exactly how many angiographies and treatments with angioplasty or bypass surgery that could be spared in this way. It is estimated that a patient pathway based on the diagnosis of myocardial ischaemia including the type of ischaemia may render approximately half of the present angiographies and a number of invasive revascularisations redundant. This pathway implies substantial economic savings.

Angina Pectoris↗
PubMed2000

[Thirty years of coronary revascularization in stable angina pectoris. Results of randomized controlled trials].

From a survey of randomized studies we wanted to elucidate the therapeutic gain and the risk of complications with coronary artery bypass grafting (CABG) and percutaneous transluminal angioplasty (PTCA) in stable angina pectoris. The following main conclusions emerged: Invasive revascularization was associated with increased survival (reduced frequency of cardiac death or myocardial infarction) exclusively in patients with three-vessel disease and/or left main lesion accompanied by a decreased left ventricular function. This group accounted for less than 10% of treated patients. With regard to survival, patients with one- and two-vessel disease were better off with conservative treatment. Relief of angina was achieved for a number of years in the majority of patients. Angina recurred earlier following PTCA than CABG. PTCA is considered less traumatic, but a ten times higher need of additional revascularization seems to eliminate this advantage. The frequency of serious complications (including the higher risk at re-revascularization) was > or = 10% after PTCA and > or = 7% after CABG.

Angina Pectoris↗
PubMed1999

Vertebral artery flow and cervical manipulation: an experimental study.

BACKGROUND: Spinal manipulation therapy is used by millions of patients each year to relieve symptoms caused by biomechanical dysfunction of the spine. Cerebrovascular accidents in the posterior cerebral circulation are a feared complication, but little research has been done on vertebral artery hemodynamics during cervical manipulation. OBJECTIVE: The purpose of this study was to develop an experimental model for investigations of volume blood flow changes in the vertebral arteries during premanipulative testing of these vessels and during spinal manipulation therapy of the cervical spine. DESIGN AND SETTING: An experimental study in a university biomedical laboratory. MATERIAL AND METHODS: The vertebral arteries were exposed in 8 adult pigs after extensive mediastinal dissection. Volume blood flow was measured on both sides simultaneously by advanced transit-time flowmetry. RESULTS: After cervical manipulation, the vertebral artery volume blood flow increased significantly for 40 seconds before returning to baseline values in less than 3 minutes. We found no significant changes in volume flow during premanipulative testing of the vertebral arteries (DeKleyn's test). CONCLUSION: We present an experimental model for investigations of vertebral artery hemodynamics during biomechanical interventions. We found a modest and transient effect of cervical manipulation on vertebral artery volume flow. The model may have further applications in future biomechanical research, for example, to determine whether any of several spinal manipulative techniques imposes less strain on the vertebral artery, thereby reducing possible future cerebrovascular accidents after such treatment.

Analysis of Variance↗
PubMed1999

Volume flow estimation by colour duplex.

OBJECTIVE: To assess the accuracy of volume blood flow using a digitised colour duplex scanner. DESIGN: Observer-blinded experimental study. MATERIALS AND METHODS: Method comparison was performed with linear regression analysis of 89 paired observations in 11 anaesthetised pigs. A Siemens Sonoline Elegra ultrasound system was used for transcutaneous volume flow estimation using invasive transit time flowmetry by Cardiomed as a reference. RESULTS: For the individual measurement we found a standard error of the estimate (SEE) of 22 ml/min. For the regression line, however, the SEE was only 0.2 ml/min. CONCLUSIONS: Digitised colour-duplex sonography has a volume flow measurement error that is too high for single measurements in the individual patient for the method to be useful in clinical decision making, but sufficient for examinations of groups and comparison of groups.

Animals↗
PubMed1998

Divergent cardiac response to exercise in essential hypertension vs. normotension and the effect of enalapril.

The aims of this study were to examine (1) the cardiac response to exercise in essential hypertension and (2) the effect of long-term enalapril treatment on cardiac reserve. Ten normotensive control subjects and 15 patients with moderate, essential hypertension underwent radionuclide ventriculography during graded, supine exercise (0 W-50 W-100 W). The hypertensive patients were studied during monotherapy using hydrochlorothiazide and 3 and 12 months after supplementation with enalapril 10-40 mg o.d. During exercise, the control subjects demonstrated a 17% increase in left ventricular ejection fraction (LVEF) mediated by a 30% decrease in end-systolic volume, a small increase in stroke volume and a minor biphasic (increase-decrease) change in end-diastolic volume. In the hypertensive patients, both the end-diastolic and the end-systolic volume increased substantially with no increase in LVEF, although stroke volume increased by 33%. Long-term therapy with enalapril induced only a minor change towards a more normal pattern of cardiac response to exercise. The hypertensive patients increased their stroke volume during exercise by recruiting preload reserve instead of increasing contractility. Long-term treatment with enalapril had little, if any, effect on this abnormal cardiac response.

Adult↗
PubMed1998

Triplex ultrasound of vertebral artery flow during cervical rotation.

BACKGROUND: Reviewing the literature on vertebral artery flow during cervical rotation shows various results. Furthermore, most studies have investigated exclusively the effects of contralateral rotation employing less-than-optimal Doppler ultrasound technique. OBJECTIVE: The aim of this study was to use the latest advancement in Doppler ultrasound technology to investigate flow velocity in the vertebral artery during both ipsilateral and contralateral cervical rotation in normal subjects. DESIGN AND SETTING: A prospective, controlled study in a university hospital vascular laboratory. PARTICIPANTS: Twenty healthy university students. RESULTS: Peak flow velocity decreased significantly during contralateral rotation and increased significantly during ipsilateral rotation. The differences, however, were modest. We found no correlation between peak flow velocity and systolic blood pressure. CONCLUSION: With modern Doppler ultrasound technique, preventing some sources of error in measuring, our finding during contralateral rotation were in accordance with most previous studies showing a decrease in peak flow velocity. For the first time, however, we report an increased flow velocity in the vertebral artery during ipsilateral rotation.

Adult↗
PubMed1996

Improvement of upper airway obstruction after 131I-treatment of multinodular nontoxic goiter evaluated by flow volume loop curves.

Symptoms of tracheal-esophageal compression are often related to a large nontoxic goiter. The aim of the present study was to evaluate to what degree upper airway obstruction, as measured by flow volume loops, FIF50% and FEF50%/FIF50% (Forced Expiratory Flow at 50% of the vital capacity/ Forced Inspiratory Flow at 50% of the vital capacity) exists in nontoxic multinodular goiter, and whether changes occur after 131I-treatment. Thirteen patients with large multinodular nontoxic goiters were evaluated by estimation of FIF50%, FEF50%/FIF50% ratio and a graphic plot of the flow volume loop curve before and three, six and 12 months after treatment with 131I. FIF50% increased over 12 months from median 1.79 l/sec (range 1.46-3.02) to 2.84 l/sec (1.13-5.69) (p = 0.01). A progressive increase was seen over time (p = 0.001, trend analysis). The FEF50%/FIF50% ratio decreased from in 1.45 (0.32-2.26) to 1.03 (0.43-2.13) 12 months after treatment (p < 0.001). A progressive decrease was seen over time (p = 0.001, trend analysis). By visual evaluation 11 had a flow volume loop curve typical for an upper airway obstruction and in 9 patients the FEF50%/FIF50% ratio was > 1.2. In conclusion we found that upper airway obstruction is present in patients with multinodular nontoxic goiter, and seems to be reduced after 131I-treatment. Flow volume loop curves and measurement of FEF50% and FIF50% are important estimates for upper airway obstruction in these patients.

Aged↗
PubMed1995

Changes in left and right ventricular performance and volumes in seven-year survivors of acute myocardial infarction.

We describe the spontaneous long-term changes in right (RV) and left (LV) ventricular performance during a 7-year period after acute myocardial infarction (AMI). Radionuclide ventriculography was performed in the second week after AMI in 201 patients. RV and LV ejection fractions, and LV end-diastolic and end-systolic volumes were determined. A follow-up after 7 years was performed in 55 survivors. Of these, 16 patients were also examined after 1 year. During the 7-year follow-up period, LV ejection fraction decreased from 0.49 to 0.45 (p < 0.01). LV end-diastolic volume increased from 161 to 210 ml (30%) (p < 0.01), and LV end-systolic volume from 83 to 123 ml (48%) (p < 0.01). In patients without recurrent AMI, coronary artery bypass grafting surgery, or angiotensin-converting enzyme inhibitor therapy (n = 37) during follow-up, no change in average LV ejection fraction was observed. Nevertheless, this subgroup had substantial increases in LV end-diastolic volume, from 157 to 190 ml (21%) (p = 0.002) and in LV end-systolic volume, from 80 to 105 ml (31%) (p < 0.001). In a subgroup of patients also reinvestigated after 1 year (n = 16), there was a 15% increase in LV end-diastolic volume the first year after AMI with an additional 10% increase in LV end-diastolic volume between years 1 and 7. Corresponding figures for LV end-systolic volume were 20% and 12%, respectively. Hardly any association was apparent between LV ejection fraction, LV end-diastolic volume, and LV stroke volume at discharge for subsequent LV dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Left ventricle haemodynamics and vaso-active hormones during graded supine exercise in healthy male subjects.

Left ventricle systolic and diastolic functional parameters were measured by gated equilibrium radionuclide cardiography in 12 healthy men (age 33-51 years) at rest and during graded supine exercise. The leftventricle end-diastolic volume showed an initial small (11%) increase during low submaximal exercise [from mean 163 (SD 40) at rest to mean 181 (SD 48) ml], while left ventricle end-systolic volume decreased successively [from mean 59 (SD 19) to mean 39 (SD 21) ml] with increasing exercise. Stroke volume was therefore elevated at all exercise levels compared with rest [mean 104 (SD 23) ml], and the peak value [mean 128 (SD 33) ml] was found at the lowest exercise level, contributing 40% to the initial increase in cardiac output. Cardiac output increased from mean 6.2 (SD 1.4) at rest to mean 20.2 (SD 5.0) l.min-1 at maximum. Left ventricle peak ejection and peak filling rates increased from mean 449 (SD 89) and mean 442 (SD 85) ml.s-1 at rest to mean 996 (SD 227) and mean 1255 (SD 333) ml.s-1, respectively, at maximum. The myocardium oxygen consumption, assumed to be proportional to the sum of the stroke work and the potential energy, increased fourfold, but absolute values were twice as high as expected, indicating that extrapolation from data obtained in dog hearts (as we have done) cannot be directly applied to humans. Selected vaso-active hormones were measured at all exercise intensities. Noradrenaline (NA), adrenaline (A) and angiotensin II (AII) concentrations showed a very pronounced increase at maximal exercise compared with the preceding lower intensites, while atrial natriuretic factor (ANF) and cyclic guanosinemonophosphate (cGMP) concentrations showed a more continuous increase, and dopamine (DA) remained almost unchanged. This speaks in favour of a crucial role for NA, A and AII in preserving blood pressure at maximum exercise, while DA probably has no importance for the cardiovascular homeostasis during exercise. Increases in concentrations of ANF and cGMP were highly correlated (r = 0.86). Our data supported the opinion that there is a cardiac limitation to maximal performance connected to the cardiac pumping capacity.

Adult↗