PubMed Health⌕ Search

Biomedical subjects

A Federici

Publications and source records attributed to A Federici.

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

Total hip replacement using the cementless "Bio-direct" femoral component and the "CAB 1" self-threading acetabular component.

The special characteristics of the "Bio-direct" femoral component, which has been used in total hip replacement for approximately 7 years, are described. Although the current trend is to pair a cemented acetabular component with the Bio-direct femoral component, a new self-threading acetabulum (CAB 1) has recently been implanted in 12 patients. This new acetabular component is fully illustrated.

Acetabulum↗
PubMed1991

[Blood acceleration is the principal factor in coronary flow increase during exercise test].

Continuous wave Doppler evaluation of the blood flow velocity in the internal mammary artery anastomosed to the left anterior descending coronary artery is a technique for assessing human coronary flow that shows a good reproducibility and lower change in Doppler angle between resting and supine exercise conditions. In this study the reciprocal changes which occur in coronary blood flow, coronary stroke volume, coronary resistance and blood pressure have been studied. During supine exercise coronary stroke volume remains constant and the increase of blood cells acceleration is necessary to have the shortening of cardiac cycle. This parameter is inversely dependent on the coronary resistances and directly dependent on blood pressure. As a consequence it plays the main role in increasing coronary blood flow during exercise.

Adult↗
PubMed1990

Doppler continuous-wave analysis of grafted mammary artery as a non-invasive technique for static and dynamic assessment of coronary flow in man.

In this paper, Doppler continuous-wave analysis of blood velocity in the internal mammary artery, anastomosed to the left coronary vascular bed in humans who have undergone myocardial revascularization, is proposed as a non-invasive technique to study coronary blood flow during physiological procedures which cause it to change. Blood velocity curves obtained in normal and anastomosed internal mammary arteries were compared during hyperventilation and the Valsalva manoeuvre. During hyperventilation, blood velocity increased in the normal mammary but not in the anastomosed artery. During the expiratory effort of the Valsalva manoeuvre, the mean blood velocity decreased in the normal mammary artery but it did not change significantly in the anastomosed artery. Variations in the mean velocity were largely prevented by simultaneous and well-balanced increases and decreases in the diastolic and systolic velocities, respectively.

Anastomosis, Surgical↗
PubMed1989

A model for the relationship between the arterial pressure and the heart period.

This paper provides a simple model for predicting the relationship between steady-state heart rate and arterial blood pressure. Two current state-of-the-art models of the cardiovascular system as a pump operating in its circuit are reformulated and combined in order to highlight the role of the duration of the heart cycle. The proposed model establishes that the cardiac cycle lengthens linearly with the inverse of the average blood pressure. Experimental data are reported for sixteen preoperated conscious dogs resting quietly on their sides. Vagal and sympathetic blocks have been produced in four dogs in order to obtain a wide range of sympathetic and parasympathetic tones, namely, to cover the entire range of physiological values of the heart rate. For these dogs a comparison between the experimental values and the theoretical predictions shows a good agreement, the results of the linear regression model being statistically significant at the p = 0.001 level for three dogs and at the p = 0.01 level for the fourth dog.

Animals↗
PubMed1989

[Doppler velocimetry of the internal mammary artery anastomosed to the anterior descendent coronary artery: a noninvasive analysis of coronary circulation].

This study analyses the static and dynamic characteristics of the flow curves obtained by continuous wave Doppler flow velocity analysis in the internal mammary artery (IM) under normal conditions and after left anterior descending coronary artery by-pass. The IM flow velocity curve has the characteristics of a muscular artery both in basal conditions and during hyperventilation and Valsalva manoeuvre. On the other hand, the by-passed IM shows a typically phasic flow velocity curve, the diastolic flow prevailing over the systolic as is commonly the case in the coronary circulation. This curve also shows variations characteristic of the coronary circulation during Valsalva manoeuvre, whereas it is not affected by the alterations induced by hyperventilation in the area of the respiratory muscles. Continuous wave Doppler flow analysis of the by-passed IM can therefore be considered a reliable method for evaluating coronary flow in man. The fact that this method is non-invasive makes it obviously advantageous and widens its field of application not only to strictly diagnostic evaluations but also to physiopathological and therapeutical ones.

Anastomosis, Surgical↗
PubMed1988

Intraoperative fractures of the femoral diaphysis in hip arthroprosthesis surgery.

The authors reviewed 14 cases of fracture of the femoral diaphysis which occurred during 602 hip arthroprosthesis operations. They attempted to ascertain the role of local and general factors in this complication. In 5 cases there was obvious structural alteration in the upper third of the femur with decreased bone resistance; in 5 cases there was abnormal morphology of the diaphyseal canal (morphological incongruence) due to hip dysplasia or previous osteotomy; in 3 cases there was marked dimensional incongruence between the prosthetic stem and the medullary canal and in the remaining case abnormal morphology of the medullary canal was associated with dimensional incongruence. From an analysis of the cases it emerged that complete fractures in cemented arthroprostheses negatively influenced the long-term results while fractures occurring in arthroprostheses with biological fixation do not significantly modify the normal progression. Finally, the authors stress that a careful preoperative evaluation of the radiographs may considerably reduce the incidence of this complication.

Adult↗
PubMed1987

Life-threatening reaction to factor VIII concentrate in a patient with severe von Willebrand disease and alloantibodies to von Willebrand factor.

A 16-yr-old girl with severe von Willebrand disease complicated by the development of precipitating alloantibodies to von Willebrand factor (anti-VWF) had a life-threatening anaphylactoid reaction immediately after the infusion of a commercial plasma concentrate of factor VIII/von Willebrand factor. An early post-infusion activation of the complement system was demonstrated by the appearance of C3 split products and by the drop of serum CH50 activity, occurring in parallel with a post-infusion drop in the anti-VWF antibody levels. Immune complexes remained unchanged in the early post-infusion period and rose to a moderate extent only after 24 h. We conclude that biologically active products of the complement system contributed to the onset of this life-threatening reaction which occurred after concentrate infusion.

Adolescent↗
PubMed1986

Nail-patella syndrome (hereditary osteo-onychodysplasia). A case report.

The present paper reports a case of osteo-onychodysplasia (nail-patella syndrome). There are very few descriptions of this syndrome in the orthopaedic literature, possibly because it is rare for the morphological changes in the knee and the associated abnormalities to require or be amenable to treatment. In the present case an accidental sprain of the right knee caused recurrent dislocation of the patella that necessitated surgical intervention.

Adult↗
PubMed1985

Role of the autonomic nervous system in the control of heart rate and blood pressure in the defence reaction in conscious dogs.

The present study was performed on conscious, chronically instrumented dogs, which underwent selective blockade of sympathetic adrenergic and vagal outflows. Excitements were performed on these animals in normal states (N), after chronic treatment with guanethidine, for sympathetic blockade (SB), after cold vagal blockade (VB), and after combined sympathetic and vagal blockade (SB + VB). Heart rate and arterial blood pressure were monitored in all the experiments, while a group of dogs was also tested with an electromagnetic flowmeter on the superior mesenteric artery. The role of the sympathetic and parasympathetic controls in the defence reaction was assumed from comparison of experiments performed in the presence or in the absence of each (or both) autonomic component(s). In the SB + VB condition, excitement was followed by sudden hypotension, without changes in heart rate. In VB experiments, a brief and transient hypotension appeared, followed by gradually developed hypertension, while heart rate progressively rose in about 5 s; there was no sudden increase in mesenteric vascular resistance, which contrasted with the very marked reaction in N experiments. Under vagal control alone (SB), the stimulus elicited prompt tachycardia and hypertension, followed by a period of moderately reduced blood pressure. We conclude that, while the defence reaction leads to a sudden fall of arterial blood pressure, in the absence of compensatory mechanisms, both branches of the autonomic nervous system play a protective role against hypotension. In addition, the modulation of the vagal outflow, leading to sudden changes in the heart performance, seems to be responsible for the initiation of the overall haemodynamic adjustments following excitements. The possibility that withdrawal of the parasympathetic outflow to the heart may raise arterial blood pressure was verified in a special experiment in which artificial vagal stimulation in a conscious (vagal blocked) dog, was turned off for brief periods, before and after guanethidine. This led to changes in blood pressure and heart rate very similar to those seen at the onset of the defence reaction, both in N and SB conditions.

Aggression↗
PubMed1985

Profound alterations of the multimeric structure of von Willebrand factor in a patient with malignant lymphoma.

Laboratory investigation of an acquired haemorrhagic diathesis in a 63-year-old man with malignant lymphoma revealed the classical haemostatic defects found in von Willebrand's disease (vWD). In addition, SDS-agarose gel electrophoresis demonstrated alterations of the von Willebrand factor (vWF) multimeric structure. A profound defect of large and intermediate size multimers was observed which was different from those seen in variants of congenital vWD. In vitro, weak inhibitory activity against factor VIII procoagulant activity and ristocetin cofactor activity was present in the patient's plasma. When patient's plasma was incubated with normal plasma, followed by centrifugation, vWF antigen (vWF:Ag) was precipitated. In vivo, after transfusion of cryoprecipitate, there was rapid plasma clearance of vWF:Ag and ristocetin cofactor and of FVIII coagulant activities.

Factor VIII↗
PubMed1984

Aortic pressure and heart rate patterns during the respiratory cycle in different autonomic conditions in conscious dog.

The relation between respiratory cycle and aortic pressure and heart rate patterns has been studied in the spontaneously breathing conscious dog in four experimental conditions: presence or absence of both vagal and sympathetic activity, presence of activity of only one autonomic branch. Chronic treatment with guanethidine was used to block adrenergic system, while acute, reversible blockade of activity in the cervical vagus was obtained by cooling the nerve. Vagal block was performed before and after guanethidine. In absence of vagal activity, aortic pressure decreased during inspiration and increased during expiration. This pattern was reversed by vagal activity, while it was enhanced by sympathetic activity. The integrative effects of the two branches are responsible for the classic "pulsus paradoxus". The comparison of the four experimental conditions is compatible with the hypothesis that variations of left ventricular preload play the major role in the regulation of ventricular output during respiratory cycle, while the relation between left ventricular output and aortic pressure is largely dependent on autonomic activity.

Animals↗
PubMed1983

[Temporal decay of the effect of a single vagal stimulation on cardiac rhythm in the rabbit].

The negative chronotropic effect of a single stimulus randomly delivered through right, left or both vagi respectively, within the cardiac cycle was studied in anaesthetized rabbits. The effect was analyzed on the P-P cycles subsequent the stimulus application, calculating percentagewise the delay observed in definite time-lapses, equalized to two pre-stimulus cycles. The results indicate that the efficacy of the negative chronotropic effect of vagal stimulation shows the least delay the closer the stimulus to the wave, while the delay is higher when the stimulus is delivered within the central portion of the cycle.

Animals↗
PubMed1983

[Integration of the effects of a single stimulus applied to the vagus nerve on the right and the left, in the rabbit heart].

It was reported by the literature that a train stimulation, simultaneously delivered on the two vagi, resulted in a decrement of the negative chronotropic effect, when it was compared to the sum of the effects obtained by the stimulation of the two nerves, separately. Our data indicate that the size of the chronotropic effect obtained by the simultaneous application on the two vagi of a single supraliminar stimulus, randomly applied within the P-P cycle, in rabbits, can be equal, higher or lower than the sum of the same stimulation separately delivered to the two nerves. The results could depend upon the different amount of acetylcholine released during stimulation. The hypothesis is put forward that different patterns of the neuro-cardiac junction regulation might be activated according to the quantity of released neuromediator.

Animals↗
PubMed1983

Time-dependency of the response to a single vagal stimulus in the rabbit heart.

The time-dependency of vagal effects on P-P cycle was studied in rabbits, chosen because of high heart rate, in order to verify the occurrence of this phenomenon already described for animals with lower heart rate. In five rabbits with different resting cardiac cycles, vagal stimuli were delivered randomly. The results indicate that for heart rates higher than 120 beats/min no occurrence of Brown and Eccles' time-dependency was observed. It is evident, however, the different responsiveness of the pacemaker to vagal stimuli delivered at different times of the cardiac cycle. In particular a stimulus given beyond 40-50% of the cardiac cycle does not affect the same but the next cycle.

Acidosis↗