Relationship between ST-segment elevation and local tissue flow during myocardial ischaemia in dogs.

The relationship between electrocardiographic ST-segment changes and local tissue flow recorded from idential sites in the myocardium was determined by inserting platinum electrodes into the left ventricular wall of anaesthetized dogs. Local myocardial blood flow was measured during graded coronary constriction by recording tissue hydrogen desaturation rate. In the detection of ischaemic ST-segment elevation, intramural recordings proved to be more sensitive than corresponding epicardial recordings. Significant ST-segment elevation could only be detected by reducing local myocardial flow below 50% of control; by further reduction ST-segment elevation increased in proportion to the reduction in myocardial flow. Thus, significant myocardial ischaemia might exist without electrocardiographic alterations.

Effects of adrenaline infusion on platelet number, volume and release reaction.

At the end of a diagnostic right heart catheterization ten patients received an intravenous infusion of l-adrenaline which gradually increased the arterial plasma adrenaline concentration from resting physiological values to high values as seen during myocardial infarction, pheochromocytoma and hypoglycemia. Blood was sampled from the brachial artery, femoral vein and hepatic vein. During the adrenaline infusion venous beta-thromboglobulin concentrations increased 23% from 61 +/- 5 to 80 +/- 7 micrograms/l (mean +/- SE), arterial platelet counts 20% from 212 +/- 17 to 253 +/- 25 X 10(9)/l and arterial platelet volume 4% from 7.25 +/- 0.20 to 7.56 +/- 0.21 femtoliter. All changes were significant at the 5% level. Thus, acute increments of arterial plasma adrenaline significantly stimulated the blood platelet parameters studied.

Functional and antigenic antithrombin III values in plasma and serum from 115 regular blood donors and antithrombin III in prediction of postoperative thrombosis.

Antithrombin III (AT-III) was determined functionally using chromogenic substrate (S-2238) and immunologically using radial immunodiffusion (RID) in plasma and serum from 115 blood donors. There was a decrease in functional activity by 43.5% and in antigen concentration by 18.4% during in vitro coagulation when corresponding serum and plasma samples were compared. A positive correlation was found between the two methods in plasma (r = 0.784) as well as in serum ( r = 0.658). RID in serum correlated well with RID in plasma (r = 0.811), but the correlation for S-2238 in plasma and serum was poor (r = 0.411). Functional AT-III decrease during coagulation was uncorrelated with age and fibrinogen, and was not statistically affected by sex, smoking or blood groups. Preoperative functional AT-III activity was measured in 25 patients undergoing elective hip replacement, 60% of whom developed postoperative thrombosis. The functional activity in serum discriminated well between the thrombotic and nonthrombotic group of patients (p less than 0.025), whereas the activity in plasma showed only a minor difference.

Acute hemodynamic effects of propranolol, glycerylnitrate, and exercise in coronary patients with left ventricular dysfunction.

Some adverse effects of beta-blockers in heart failure are counteracted by glycerylnitrate. However, the hemodynamics in this condition after giving both drugs are not well known. We examined the drug combination in exercising coronary patients with left ventricular dysfunction. Elevated left ventricular end-diastolic pressure was a measure of dysfunction. A right-heart catheterization with three successive exercise stress tests was done in 40 patients. At repeated exercise without drugs a "warming up" phenomenon was observed, consisting of small but statistically significant reductions in pulmonary capillary wedge pressure, and heart rate. At exercise propranolol reduced heart rate, cardiac output, systemic blood pressure, left ventricular work, and increased arteriovenous oxygen difference. Glycerylnitrate reduced pulmonary capillary wedge pressure at exercise, but, contrary to the findings at rest, it did not increase heart rate or reduce cardiac output. The drug combination resulted in hemodynamics that were similar to those after propranolol alone, except for a lower pulmonary capillary wedge pressure. The drug combination allowed the patients to exercise with the benefits of the beta-blocker, but at a lower ventricular filling pressure. Thus, the potential hazard of giving beta-blockers to patients with left ventricular dysfunction may be reduced by adding glycerylnitrate.

Basic concepts of femoral neck anteversion: comparison of two definitions.

Femoral neck anteversion is determined by the neck, shaft and knee axes. It is commonly assumed that the neck axis is a straight line connecting the centre of the femoral head, the centre of the femoral neck and the axis of the femoral shaft. However, the line through the centre of the femoral head and neck crosses anterior to the axis of the femoral shaft. A distinction has therefore to be made between two principal different definitions of anteversion, denoted ANTEV 1 and ANTEV 2 in this paper, depending on the precise definition of the neck axis. Previous studies have indicated substantial differences between these definitions. The present study, using precise measuring methods, shows that the definitions have a systematic but small spread of differences. The large individual variation previously found between the two definitions is therefore caused mainly by the measuring methods and to a lesser extent by real anatomical variations.

Evaluation of threatened abortion by human chorionic gonadotropin levels and ultrasonography.

To determine the prognostic value of human chorionic gonadotropin (HCG) concentrations in maternal plasma and urine, we studied 104 women with threatened abortion (cases) and 108 women with normal pregnancies and normal serum levels of HCG (controls). Of the 104 cases, 48 were also examined ultrasonically. We concluded that measurements of serum levels of HCG are of more accurate prognostic value than those of urine levels. Low serum levels of HCG indicate a poor prognosis for the pregnancy, as do steady decreases, in repeated measurements, of initially high HCG level. The combination of normal serum levels of HCG and signs of fetal life during ultrasonic examination indicates a very good prognosis for the pregnancy.

[Investigation of accidents by the Special Inspection for Electrical Electrical Medical Equipment]. / Uhellsetterforskning ved Det saerlige tilsyn med elektromedisinsk utstyr.

The article reviews the responsibilities of the Special Inspection for Electrical Medical Equipment, STEM, with emphasis on investigations of accidents and near-accidents in connection with the use of technical equipment. It stresses the obligation to report to STEM immediately. The reported accidents for the period 1980-1988 are given in table 1, and are discussed. Norwegian statistics are compared with both American and Scandinavian data and reference is made to the international standardization on technical medical equipment.

Aspects of femoral neck anteversion. Theoretical considerations and experimental results.

Although the general definition of femoral neck anteversion seems to be accepted, the details vary substantially and some measuring methods are based on anatomic prerequisites that are lacking. This may be a cause of inconsistent and incorrect determinations. An anatomic study was therefore performed. Only small differences were found between two neck axes and different methods for delineating the axes. Inconsistent use of the shaft axis gave substantial variations. The long axis of the femoral shaft was, however, not shown to be a source of substantial error. The variation between three different knee axes was substantial. The cross section of the femoral neck was found to be radially asymmetric. Therefore, a precise and unequivocal neck centre cannot be made by any combination of bi-plane projections of the neck.

Lack of correlation between femoral neck anteversion and acetabular orientation. Radiography and computed tomography in cadavers and in vivo.

Radiography and computed tomography measurements were made of femoral neck anteversion, femoral head cartilage distribution, and the orientation of the acetabulum. The measurements were made in elderly cadaver femurs and in patients. They failed to establish any correlation between the femoral neck anteversion and the orientation of the articulating surface of the femoral head, nor between the femoral neck anteversion and the angles of the acetabulum.

Evaluation of three methods for measurement of femoral neck anteversion. Femoral neck anteversion, definition, measuring methods and errors.

A variety of methods exist for determining femoral neck anteversion. There is, however, no consistent definition or reference method by which the correctness of the measurements can be determined. In this report the precision of a specific definition of femoral neck anteversion is estimated by means of a reference method. Three different radiologic measuring methods based on fundamentally different principles are evaluated by comparison with this reference. It is concluded that: 1) The Dunlap/Rippstein method can be recommended as the standard method. 2) Computed tomography may have substantial sources of error. 3) Methods based on arbitrary projections have poor precision.

Strength of femoral neck fracture fixation. Comparison of six techniques in cadavers.

A neck osteotomy parallel to the femoral shaft was made on 36 cadaveric femora using the contralateral intact femur as a control. The osteotomies were fixed using a Thornton nail, two von Bahr screws, three Gouffon screws, three Knowles pins, a Haukebø compression screw, or an AO compression screw. The femora were then tested for bending strength using the load ratio test/control at 2- and 5-mm displacement as an expression of the relative strength of the osteosynthesis. There was no difference between the von Bahr, Haukebø, and the AO screws. These implants gave stronger fixation than the Thornton nail, Gouffon screws, and Knowles pins. The Thornton nail was stronger than three Gouffon screws or Knowles pins. The relatively stronger compression hip screws were thus not superior to two optimally placed 5-mm screws.

Femoral neck angles: a specimen study with special regard to bilateral differences.

The femoral neck angles were determined in 48 pairs of normal specimens from cadavers of elderly Norwegians, 24 males and 24 females. The anteversion angle was found to average 10.4 degrees +/- 6.7 degrees and the neck-shaft 127.7 degrees +/- 7.6 degrees. There were no significant differences between the sexes. The bilateral differences were analysed. The 95 per cent confidence limits of the anteversion and head-neck-shaft angles were calculated to be 11.8 and 13.8 degrees, respectively.

Changes in coronary haemodynamics and myocardial metabolism at rest and during exercise after a cardiotonic drug (prenalterol) in patients with coronary artery disease.

To elucidate the myocardial metabolic and haemodynamic effects of an inotropic drug in patients with coronary artery disease (CAD) without evident congestive heart failure (CHF), the acute effects of prenalterol were studied in nine patients. Patients with documented CAD by leftsided cardioangiography and end-diastolic pressure greater than 15 mm Hg were included in the study. They were examined at rest and during supine exercise at a level just below their anginal threshold before and after prenalterol. At rest, rate pressure product (RPP) increased by 40% (P less than 0.01), cardiac index rose 20% (P less than 0.01), cardiac venous flow (CVF) increased by 18% (P less than 0.05), and myocardial oxygen consumption (MVO2) increased by 20% (P less than 0.05) after prenalterol administration. Despite a decrease in mean pulmonary capillary venous pressure (PCV) of 40% (P less than 0.01), myocardial lactate extraction fell significantly (P less than 0.01) and lactate production was observed in three of nine patients compared to before prenalterol administration. During exercise, RPP increased by 20% (P less than 0.01), cardiac index remained unchanged, CVF increased by 25% (NS) and MVO2 showed a tendency to an increase (NS) after prenalterol administration. Mean PCV pressure decreased by 30% (P less than 0.01). Myocardial lactate extraction was markedly reduced during exercise (P less than 0.01) and five of nine patients showed lactate production compared to that before prenalterol administration. Thus, despite a decrease in left ventricular filling pressure, increased myocardial oxygen demand occurred after acute administration of prenalterol. Prenalterol and probably similar inotropic drugs should be used cautiously in patients with CAD without clinical evidence of congestive heart failure.

Renal haemodynamic and sympathetic responses to head-up tilt in essential hypertension.

Nine mild-to-moderate hypertensive patients (HT), aged 41 +/- 0.6 years (mean +/- SEM) and nine age-matched normotensive control subjects (NT) were tilted to 60 degrees for 10 min. During tilt, both systolic (S) blood pressure (BP) (p less than 0.01) and diastolic (D) BP (p less than 0.05) increased in HT, but not in NT. At supine rest renal blood flow was higher in HT than in NT and increased by 17% in HT during tilt, while a decrease of 13% was observed in NT (p less than 0.05). Renal vascular resistance was unchanged in HT during tilt, while a significant increase (p less than 0.01) was observed in NT. Arterial plasma noradrenaline increased in both groups (p less than 0.05) during tilt, significantly more in HT than in NT (p less than 0.05). No statistically significant difference was observed between the groups in renal catecholamine uptake or release. Our data indicate enhanced general sympathetic and circulatory responses to tilt in subjects with mild-to-moderate essential hypertension. However, the enhanced haemodynamic and sympathetic responses were not shared by hypertensive kidneys and renovascular resistance remained unaffected by tilt.

Decreased peripheral dopaminergic activity in essential hypertension?

In 42 men aged 50 +/- 1 years with untreated, sustained essential hypertension and in 34 age-matched normotensive men plasma free dopamine concentrations in venous blood in the standing position were more than 60% higher than supine values indicating dopamine involvement in the orthostatic response. In both the hypertensive and normotensive group supine arterial plasma dopamine concentrations were significantly higher than venous supine (P less than 0.004) indicating release of this catecholamine from central organs such as brain, kidneys or adrenals. In the hypertensive group both venous supine, arterial and venous standing plasma dopamine concentrations and the urinary excretion of this catecholamine were lower than in the normotensive group. Between the groups, statistical significance was achieved for venous standing dopamine concentrations (P less than 0.04) and when venous supine, arterial and standing plasma concentrations were added together for each individual (P less than 0.03). The findings may indicate decreased peripheral dopaminergic activity in patients with essential hypertension.

Dietary sodium intake increases vasopressin secretion in man.

Plasma vasopressin concentration and urinary vasopressin excretion were measured in a control situation, during sodium depletion and on days 1, 2, and 7 during high sodium intake in twelve 23-26-year-old men on a free-water intake. Urinary vasopressin excretion decreased from 6.7 +/- 1.0 ng/hr (control) to 3.9 +/- 0.3 ng/hr (p less than 0.01) when sodium excretion decreased from 188 +/ 18 to 16 +/- 2 mmol/24 hr. During the first day of high sodium intake, the urinary vasopressin excretion increased to 10.0 +/- 1.2 ng/hr (p less than 0.01) compared with control and remained high throughout the sodium repletion. Through all collection periods at low, normal, and high sodium intake, vasopressin excretion increased concomitantly with serum sodium concentration and osmolality. After low sodium intake for 7 days, the serum vasopressin concentration averaged 2.7 +/- 0.6 ng/l, and this level was maintained throughout the sodium repletion period. These results are compatible with a stimulatory effect of dietary sodium intake on pituitary vasopressin secretion in man. Dietary sodium may stimulate vasopressin secretion through extracellular osmolality or even by a direct effect of extracellular sodium on periventricular receptors. Plasma renin concentrations or sympathetic nervous activity offered no further explanations. Urinary vasopressin excretion provides more useful information than do plasma concentrations, as the latter can fluctuate rapidly.