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Biomedical subjects

J Marving

Publications and source records attributed to J Marving.

16 recordsLinked to original sources
PubMed1992

Does alfentanil preserve left ventricular pump function during rapid sequence induction of anaesthesia?

A double-blind, randomised trial was conducted in 24 patients without cardiopulmonary disorders (20-43 years), to assess the effect of an intravenous bolus of alfentanil on the circulatory and catecholamine responses to rapid sequence induction of general anaesthesia. Induction included injection of thiopentone 5 mg/kg and suxamethonium 1.5 mg/kg in rapid succession, followed by laryngoscopy and intubation. Half of the patients received alfentanil 100 micrograms/kg immediately before thiopentone. The other half received saline. Blood pressure, heart rate, and plasma catecholamine concentrations were measured repeatedly, together with left ventricular ejection fraction assessed by radionuclide angiocardiography. The responses following laryngoscopy and intubation were completely different in the saline vs. the alfentanil group: rate pressure product +76% vs. -32%, mean arterial blood pressure +46% vs. -25%, heart +46% vs. no change, noradrenaline +117% vs. -25%, adrenaline +50% vs. -53%, and left ventricular ejection fraction -32% vs. no change. In conclusion, during rapid sequence induction of anaesthesia with thiopentone and suxamethonium, an intravenous bolus of alfentanil 100 micrograms/kg 1 min before laryngoscopy and intubation completely prevents hypertension, tachycardia, decrease in left ventricular ejection fraction, and activation of plasma catecholamines, though at the expense of moderate hypotension.

Adult↗
PubMed1992

Acute plasma expansion: left ventricular hemodynamics and endocrine function during exercise.

In 11 healthy subjects (8 males and 3 females, age 21-59 yr) left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes were measured in the supine position by isotope cardiography at rest and during two submaximal one-legged exercise loads before and 1 h after acute plasma expansion (PE) by use of a 6% dextran solution (500-750 ml). After PE, blood volume increased from 5.22 +/- 0.92 to 5.71 +/- 1.02 (SD) liters (P < 0.01). At rest, cardiac output increased 30% (5.3 +/- 1.0 to 6.9 +/- 1.6 l/min; P < 0.01), stroke volume increased from 90 +/- 20 to 100 +/- 28 ml (P < 0.05), and LVEDV increased from 134 +/- 29 to 142 +/- 40 ml (NS). LVESV was unchanged (44 +/- 11 and 42 +/- 14 ml). Heart rate rose from 60 +/- 7 to 71 +/- 10 beats/min (P < 0.01). The cardiac preload [central venous pressure (CVP)] was insignificantly elevated (4.9 +/- 2.1 and 5.3 +/- 3.0 mmHg); systemic vascular resistance and arterial pressures were significantly reduced (mean pressure fell from 91 +/- 11 to 85 +/- 11 mmHg, P < 0.01). Left ventricular peak filling and peak ejection rates both increased (19 and 14%, respectively; P < 0.05). During exercise, cardiac output remained elevated after PE compared with the control situation, predominantly due to a 10- to 14-ml rise in stroke volume caused by an increased LVEDV, whereas LVESV was unchanged. CVP increased after PE by 2.1 and 3.0 mmHg, respectively (P < 0.05).2+ remained unchanged during exercise compared with rest after PE in

Adult↗
PubMed1991

Left ventricular peak filling rate, heart failure and 1-year survival in patients with acute myocardial infarction.

Radionuclide left ventricular (LV) peak filling rate (PFR) was determined in 185 survivors of acute myocardial infarction (AMI) and expressed in units of (1) end-diastolic volume per second (EDV s-1). (2) stroke volume per second (SV s-1), or (3) actual millilitres of blood filled into the left ventricle per second (ml s-1). The purpose of the study was to assess the interrelationship between the three expressions of PFR, and to analyse their significance with regard to signs of congestive heart failure and 1-year survival in patients with AMI. PFR EDV s-1, PFR SV s-1 and PFR ml s-1 had a poor relationship to each other, were all influenced by LV volumes and ejection fraction, and supplied contradictory information with regard to LV filling in patients with heart failure. None of the three expressions of LV peak filling rate had an association to heart failure that was independent of LV volume and ejection fraction. A low PFR EDV s-1 in contrast to a high PFR SV s-1 was associated with a high 1-year cardiac mortality, suggesting that these 'normalized' indices of LV peak filling rate signalled LV size and stroke volume rather than actual LV filling behaviour. No association was present between PFR ml s-1 and 1-year mortality. We conclude that the clinical use of radionuclide LV PFR in patients with AMI may lead to spurious results, unless the influence of LV size and ejection fraction is taken into consideration.

Diastole↗
PubMed1991

Effects of atropine on left ventricular volumes and ejection and filling rates at rest and during exercise.

1. The influence of the parasympathetic nervous system on left ventricular function including ejection and filling rates was studied by radionuclide cardiography in eight healthy young men at rest and during upright exercise. 2. After parasympathetic blockade induced by atropine, the mean heart rate (HR) at upright rest increased from 67 to 114 beats min-1, cardiac output (CO) from 4.05 to 5.17 1 min-1 (both P less than 0.001), and the diastolic blood pressure by 13 mm Hg (P less than 0.01). 3. Stroke volume (SV), left ventricular end diastolic and end systolic volume all decreased significantly after atropine. The relative ejection time increased from 0.33 to 0.51 of the cardiac cycle length (P less than 0.001), and the appropriate ejection and filling rates increased by 13% (P less than 0.05) and 147% (P less than 0.001), respectively. Haemodynamic changes in the supine position were virtually the same. 4. During exercise atropine increased HR from 115 to 146 beats min-1 (P less than 0.001) and CO by 12% (P less than 0.05), whereas SV decreased by 12% (P less than 0.05) and the systolic blood pressure by 16 mm Hg (P less than 0.001). Changes in ejection and filling rate of the left ventricle were of the same nature as those found at rest. 5. Thus apart from its HR limiting properties, secondary effects of parasympathetic nervous tone are dilatation of the left ventricle and enhancement of ejection, effects that are counteracted by atropine.

Adult↗
PubMed1991

Left-ventricular performance, volumes, and catecholamine responses during anaesthesia induction--monitoring by combined radionuclide cardiography and right heart catheterization.

Sequential radionuclide imaging and continuous recording of arterial and right heart pressures were carried out during anaesthesia with midazolam 0.2 mg kg-1, pancuronium 0.15 mg kg-1 and fentanyl 10 micrograms kg-1 in eight patients with normal cardiopulmonary status scheduled for craniotomy. The aim was to examine how a stress-free anaesthetic induction tailored to protect against the hypertension and tachycardia provoked by laryngoscopy and intubation influenced left-ventricular performance, left-ventricular loading conditions and plasma catecholamine concentrations. During the 20-min study period no significant changes were observed in heart rate, left-ventricular ejection fraction, ratio of peak systolic pressure to left-ventricular end-systolic volume, pulmonary capillary wedge pressure, left-ventricular end-systolic volume, cardiac output, dopamine and noradrenaline concentrations. Except for a minor increase in mean arterial pressure after laryngoscopy and intubation, mean arterial pressure decreased 24%, left-ventricular end-diastolic volume decreased 15%, and left-ventricular stroke volume decreased 21%. Central venous pressure increased by 75% but there was no parallel increase in pulmonary wedge pressure, which in turn did not reflect the alterations in ventricular end-diastolic volume. Plasma adrenaline concentrations decreased significantly (66%). The chosen induction regimen preserved global left-ventricular pump function during laryngoscopy and intubation without any activation of the sympathetic nervous system. Central venous and pulmonary wedge pressures were unreliable in the assessment of ventricular preload during induction of general anaesthesia.

Adult↗
PubMed1990

Left ventricular volumes in the recovery phase after myocardial infarction: relation to infarct location, left ventricular function and one-year cardiac mortality.

Absolute left ventricular volumes, normalized to body surface area, were determined by a count-based radionuclide technique in 189 patients with myocardial infarction (MI). All examinations were performed in the second week after MI. Fifty-three percent of the patients had an increased end-diastolic volume index (EDVI) and 72% an increased end-systolic volume index (ESVI). Patients with anterior MI had the same median EDVI as patients with inferoposterior MI, but significantly higher median ESVI and significantly lower median stroke volume index (SVI). SVI was subnormal in 19% of the 189 patients and left ventricular ejection fraction (LVEF) was subnormal in 67%. A non-linear, inverse relationship was present between EDVI and LVEF and between ESVI and LVEF, but LVEF varied greatly for any degree of ventricular dilatation. During a 1-year follow-up period, death from cardiac causes occurred in 29 patients. A strong relationship was present between the degree of ventricular dilatation and 1-year mortality, as well as between the degree of SVI or LVEF reduction and 1-year mortality but, next to clinical heart failure, LVEF was the single most powerful predictor of cardiac death, and various combinations of EDVI, ESVI and SVI did not add more prognostic information to that obtained by heart failure than did LVEF.

Aged↗
PubMed1990

Observer variation in the scintigraphic diagnosis of solitary cold thyroid lesions.

In order to evaluate the reproducibility of the diagnosis of solitary cold thyroid lesions, two specialists in nuclear medicine and two specialists in endocrinology independently twice read 240 thyroid 99mTc pertechnetate scintigrams. No significant difference or interaction between the results obtained from the right and the left lobe was found. A solitary cold lesion was diagnosed in 100 of the 480 lobes; however, in only 30 did all four observers agree upon the diagnosis. Interobserver variation was determined by pairwise comparison of observers. The observed agreement was between 0.91 and 0.94. After adjusting for expected chance agreement, kappa values between 0.57 and 0.70 were found. Intraobserver variation was smaller than interobserver variation, revealing agreement rates of 0.93-0.96 and kappa values between 0.71 and 0.77. Agreement was related to large lesions, lesions located centrally in the lobe, and ovoid-shaped lesions. Clinicians should be aware to what extent they can rely on the information they use in their decisions. The considerable inconsistency in the evaluation of cold lesions on thyroid scintigrams should be taken into consideration, and calls in question the value of using thyroid scintigrams for deciding whether a patient should be referred for operation or biopsy.

Adolescent↗
PubMed1990

Does the decrease in heart rate prevent a detrimental decrease of the end-systolic volume during central hypovolemia in man?

Central hypovolemia occurring with epidural anesthesia was investigated by measurement of hemodynamic and endocrine variables in 10 patients. Responses fell into two categories. Four patients experienced a hypotensive bradycardic episode after seventeen +/- four minutes. In this group epidural anesthesia initially induced a tendency toward an increase in heart rate from 65 +/- 4 to 73 +/- 5 beats/min concomitantly with decreases in end-diastolic (172 +/- 22 to 138 +/- 16 mL), end-systolic (67 +/- 12 to 51 +/- 9 mL), and stroke (105 +/- 10 to 85 +/- 7 mL) volumes (radionuclide cardiography). A subsequent decrease in mean arterial pressure from 76 +/- 3 to 67 +/- 4 mmHg was associated with a decrease in venous return as reflected by the decrease in cardiac output from 6.1 +/- 0.4 to 4.7 +/- 0.7 L/min. In this situation when the venous return was critically reduced, the heart rate was 49 +/- 4 beats/min and no further reduction in end-diastolic and end-systolic volumes was observed. The observed endocrine changes were compatible with a response to central hypovolemia. In the other 6 patients the reaction to epidural anesthesia did not induce statistically significant changes in hemodynamic and endocrine variables. It is concluded (1) that the decrease in heart rate associated with central hypovolemia during epidural anesthesia seems to be elicited when the left ventricular end-systolic volume is decreased by about 25% and (2) that a further decrease in end-systolic volume during progressive central hypovolemia is avoided possibly as a direct consequence of the slowing of the heart.

Adult↗
PubMed1990

Observer variation in the assessment of scintigraphy of the thyroid gland.

In order to determine observer variation in the assessment of thyroid scintigrams two specialists in nuclear medicine and two specialists in endocrinology independently evaluated 240 thyroid pertechnetate scintigrams twice, and assessed a number of variables concerning size and isotope uptake. The observed agreement between pairs of observers for the variables ranged from 0.70 to 0.98. By the use of the kappa coefficient the observed agreement was adjusted for change agreement. Kappa can variate from -1 (total disagreement) to +1 (perfect agreement). Kappa values between 0.29 and 0.86 were found. In the intraobserver study the observed agreement ranged from 0.83 to 0.99 resulting in kappa coefficients between 0.53 and 0.96. Thus the level of agreement in the present study was "fair to substantial" for agreement in the interobserver part and "substantial to almost perfect" for agreement in the intraobserver part. No difference was found in the level of agreement between the nuclear specialists and the endocrinologists. Although the treatment of patients is based on knowledge of the case histories and clinical and laboratory findings the high degree of observer variation may lead to misclassification of a number of patients with thyroid disease and subsequently a less optimal choice of treatment.

Adolescent↗
PubMed1989

Late ventricular dilatation in survivors of acute myocardial infarction.

The purpose of this study was to assess the natural course of left ventricular (LV) volumes in the convalescent phase of acute myocardial infarction (AMI). Fifty-seven patients were examined 2 weeks and approximately 1 year after AMI by a radionuclide method allowing determination of absolute LV volumes. After 1 year the patients had fewer clinical and radiologic signs of heart failure, but median end-diastolic volume index had increased from 92 to 112 ml/m2 (p less than 0.001), median end-systolic volume index from 51 to 65 ml/m2 (p less than 0.001) and median stroke volume index from 39 to 47 ml/m2 (p less than 0.001). Patients with first anterior infarcts had significantly greater increases in end-diastolic volume index, end-systolic volume index and stroke volume index than patients with first inferoposterior infarcts. The increase in LV volumes was significantly greater in patients with clinical manifestations of heart failure than in those without these signs. Notably, changes in LV size had an unpredictable effect on LV ejection fraction.

Adult↗
PubMed1989

Atrial natriuretic factor: comparability of venous and arterial plasma measurements in man at rest and during exercise.

1. Simultaneously obtained arterial and venous plasma atrial natriuretic factor (ANF) concentrations were compared at supine rest and during graded dynamic leg exercise in 10 healthy male subjects (aged 33-51 years). 2. Arterial ANF concentrations ranged between 12 and 179 pg/ml and venous concentrations between 9 and 177 pg/ml. 3. A positive correlation between arterial and venous concentrations was found (r = 0.984). 4. Arterial ANF concentrations were higher than venous concentrations in all pairs of samples (n = 31), but the difference was small and changed little with exercise: the mean difference was 5 pg/ml at rest, 12 pg/ml during submaximal exercise and 6 pg/ml during maximal exercise. 5. The extraction ratios for ANF varied greatly, but were in general lower (P less than 0.05) during maximal exercise (median 0.07, range 0.01-0.32) than at rest (median 0.22, range 0.05-0.33). 6. It was concluded that the plasma ANF concentration in a peripheral arm vein is a good indicator of the systemic peptide concentration at rest as well as during dynamic leg exercise.

Adult↗
PubMed1989

Symptoms and signs of heart failure in patients with myocardial infarction: reproducibility and relationship to chest X-ray, radionuclide ventriculography and right heart catheterization.

102 patients with myocardial infarction (MI) were examined by three clinicians, who independently recorded the following symptoms and signs: dyspnoea, a displaced apex beat, S3-gallop, rales, neck vein distension, hepatomegaly, and dependent oedema. Chest X-ray, radionuclide ventriculography, and (in 40 patients) right heart catheterization were carried out immediately after the physical examination. The clinicians frequently disagreed as to the presence of physical signs of heart failure in individuals. Moreover, these signs were of limited value in identifying patients with pulmonary vascular congestion on chest X-ray, reduced left or right radionuclide ventricular ejection fractions, enlarged ventricular volumes or haemodynamic evidence of ventricular dysfunction. We conclude that clinicians frequently disagree in the recognition of physical signs of heart failure, and that these signs have an unpredictable relationship to radiographic, radionuclide and haemodynamic measures of ventricular performance in patients with MI. Nevertheless, physical signs are useful in identifying patients with high risk of cardiac death.

Adult↗
PubMed1987

The effect of the tricyclic antidepressant drug, nortriptyline on left ventricular ejection fraction and left ventricular volumes.

Eight patients with major depression but otherwise healthy underwent radionuclide cardiography before and during nortriptyline treatment. The second examination was performed when the nortriptyline plasma concentration was within the therapeutic range (60-150 micrograms X l-1). Heart rate, arterial blood pressure, left ventricular ejection fraction, left ventricular volumes, systolic pressure-volume ratio, and cardiac output were determined. Heart rate increased in mean by 13% (P less than 0.05). All other variables were unchanged. We conclude that nortriptyline in therapeutic doses produces no major adverse effect on left ventricular function. Routine radionuclide cardiography might be a suitable method to detect among those treated with tricyclic antidepressants the occasional susceptible patient. This may particularly apply to patients with known heart disease and to elderly patients.

Adult↗
PubMed1985

Left ventricular performance monitored by radionuclide cardiography during induction of anesthesia.

Radionuclide cardiography with 99mTc-labeled erythrocytes was carried out in three different studies comprising 20 female patients without heart or lung diseases. Left ventricular ejection fraction (LVEF) and other hemodynamic variables were measured immediately before and during induction of anesthesia (thiopental, N2O/O2, succinylcholine, laryngoscopy + oral intubation, halothane). In study 1, serial measurements of LVEF, left ventricular volume, and derived variables were obtained by gamma camera in seven patients using 3-min sampling periods. In Studies 2 and 3, LVEF was monitored serially in seven and six patients, respectively, by a portable, nonimaging probe (nuclear stethoscope) at 1-min intervals or less. The induction period was prolonged to last 24 min in studies 1 and 2, against 9 min in study 3. In studies 1 and 2 there was an increase in blood pressure and heart rate after thiopental and after laryngoscopy and intubation. In study 3 a similar increase was observed after intubation. In the gamma camera study LVEF decreased from 0.72 to 0.53 after thiopental, with no further decrease during intubation. This decrease was accompanied by an increase in end-systolic volume and a decrease in the ratio: systolic cuff pressure/end systolic volume, whereas end-diastolic volume and cardiac index remained unchanged. In the nuclear stethoscope studies, LVEF decreased both after thiopental and after intubation, in study 2 from 0.68 to 0.38 and from 0.53 to 0.41, respectively; in study 3 from 0.69 to 0.53 and from 0.57 to 0.44, respectively. Our observation, in healthy, female individuals, provide an impetus for further noninvasive radionuclide studies during anesthesia in patients with cardiovascular disease.

Adult↗
PubMed1985

Decrease in beta-receptor density explaining the development of pindolol- and prenalterol-tolerance in orthostatic hypotension.

A 58-year-old woman with diabetic autonomic dysfunction was well treated for orthostatic hypotension with pindolol. After eight months however, symptoms recurred in spite of continued treatment with pindolol. Addition of prenalterol, a beta-blocking agent with very high intrinsic sympathomimetic activity, had a marked clinical effect on her orthostatic hypotension. Before treatment with prenalterol, stroke volume and left ventricular enddiastolic volume markedly decreased during tilt, as demonstrated by radionuclide angiography. After short-term prenalterol treatment, the orthostatic decreases of stroke volume and left ventricular end-diastolic volume were less pronounced. During continued prenalterol treatment, both symptoms and haemodynamic changes recurred in the erect position. Beta-receptor density in her lymphocytes decreased from elevated levels before prenalterol to subnormal levels, when the clinical effect had disappeared. The data suggest that the tolerance development to prenalterol may be explained by the decrease in beta-adrenergic receptor density.

Adrenergic beta-Agonists↗