Oxygen free radicals and reperfusion injury; the effect of ischaemia and reperfusion on the cellular ability to neutralise oxygen toxicity.
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Biomedical subjects
Publications and source records attributed to D Medici.
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Thyroid hormone serum concentrations, the thyrotropin (TSH) and prolactin (PRL) response to thyrotropin-releasing hormone (TRH) were evaluated in patients undergoing cardiopulmonary bypass (CPB) conducted in hypothermia. During CPB a marked decrease of thyroxine (T4) and triiodothyronine (T3) concentration with a concomitant increase of reverse T3 (rT3) were observed similarly to other clinical states associated with the 'low T3 syndrome'. Furthermore, in the present study elevated FT4 and FT3 concentrations were observed. In a group of patients, TRH administered during CPB at 26 degrees C elicited a markedly blunted TSH response. In these patients, PRL concentration was elevated but did not significantly increase after TRH. The increased concentrations of FT4 and FT3 were probably due to the large doses of heparin administered to these patients. Thus, the blunted response of TSH to TRH might be the consequence of the elevation of FT4 and FT3 in serum, however, other factors might play a role since also the PRL response to TRH was blocked.
In eight patients undergoing open heart surgery for elective myocardial revascularization, extra-intracellular acid-base and water metabolism parameters were studied before and after cardiopulmonary bypass procedures. All patients presented a different degree of metabolic acidosis related to plasma lactate increase. Intracellular acid-base indexes did not change significantly, though all but one patient showed an intracellular buffers consumption. Both total muscle and extracellular water increased, while intracellular water did not change. It was concluded that low flux-low pressure perfusion CPB was related to a substantial preservation of cell integrity.
The new H2-antagonist mifentidine was tested on human atrium, in comparison with cimetidine and ranitidine, for its activity against histamine-induced inotropic effect. Mifentidine was found to be 10 times more potent than ranitidine and 100 times more potent than cimetidine. The kinetics of the three compounds are typical of a competitive antagonism and the pA2 value was of 8.60, 6.35, 5.94 for mifentidine, ranitidine and cimetidine, respectively. Our data confirm previous findings in another isolated heart preparation, namely the guinea-pig papillary muscle.
Nine patients with acute myocardial infarction underwent intracoronary urokinase infusion within 3 hours after the onset of AMI, and subsequent coronary artery by pass grafting. After thrombolytic therapy 3 patients showed single-vessel disease, 2 double-vessel disease and 4 triple-vessel disease. The ventricular function was normal in 2 patients, moderately depressed in 5 and severely depressed in 2. The coronary artery by-pass grafting was performed from 6 to days after the onset of the acute myocardial infarction (average 37 days) and the average number of grafts performed per patient was 3.2. There was no operative death. The follow up period ranged from 24 to 38 months: 7 patients are in NYHA Class I and 2, symptomatic for dispnea, are in NYHA Class II. These preliminary data suggest than the coronary artery by-pass grafting after intracoronary urokinase therapy for acute myocardial infarction can be performed safely and the surgical results do not differ from those obtained with standard coronary artery by pass grafting.
Antepartum diagnosis of syncephalus thoracopagus-conjoined twins was made at the 27th week of gestation. The authors stress the need for early recognition of this fetal malformation.
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H2-Receptor antagonists were found to possess in various degrees a negative inotropic effect on human atria in vitro. This effect seemed to be independent of H2-receptor blockade and, at least in the case of oxmetidine, seemed to involve calcium ion transport and/or utilization.
Sonography is a safe and suitable diagnostic tool; to date it appears to be the most valuable method for detecting renal cystic lesions. In particular ultrasound examination, if a wider district is screened, can demonstrate the coexistence of the cystic disease in different organs. The Authors report a case of renal polycyctic disease in which the sonographic examination was extended to the entire abdomen disclosing simultaneous involvement of the kidneys and the liver.
A psychological research on 80 patients with implanted pace-makers was carried out in order to explore their psychological adjustments following surgery. A questionnaire of 29 questions has been used. We explore the presence of anxiety due to the heart disease, to the operation or to the following period. Moreover the modification of social and family life, the relationship with the surgeon and the family doctor and, finally, the body image have been considered. The results show that the patients with implanted pace-makers, usually are able to subdue their anxiety and to recompose a good psychological equilibrium, mainly because of their favorable familiar and/or social environment.
Mechanical trauma to saphenous vein harvested and prepared for coronary artery bypass grafting may results in early and late graft occlusion due to subendothelial proliferation and to accelerated atherosclerosis. The distention of the vein a high pressure to overcome spasm and to identify leaks causes most of these pathological changes. On the basis of these considerations we developed a careful technique of vein removal and a convenient system to irrigate veins at controlled and limited pressures.
Since 1975 to 1979 24 patients affected by acute infective endocarditis were operated of valvular replacement. All patients presented increasing cardiac failure unresponsive to medical treatment; 48% of the cases had positive blood culture. In 5 patients the infective endocarditis occurred on previously implanted prosthetic valve. Surgical findings consisted in rupture of chordae tendineae, vegetation ad perforation of valvular cusps. Prosthetic valvular replacement was performed in all cases using mechanical valve (22) or porcine heterograft 85). Surgical mortality was 8,3%, while late mortality occurred on 12.5% of cases. The diagnostic considerations, concerning this disease, the surgical results and long term management are discussed.
Changes in fluid, electrolyte and acid-base balance were evaluated in 8 patients during extracorporeal circulation. H2O increase and osmolarity and colloid osmotic pressure decrease, due to priming and perfusion technique used for cardiopulmonary by pass, were found. Mild respiratory alkalosis was also present. K+ serum, because of KCL supplements, was always maintained within the normal values, while Na+ serum concentration was low, despite of large amounts of Na+ infused during perfusion. After examination of disturbances in fluid, electrolyte and acid-base balance, the Authors report the performed corrections and emphasize the importance of a prompt recognition and the immediate therapy of these changes to avert serious cardiac impairments during extracorporeal circulation or during the immediate postoperative period.
The clinical and surgical features of eight patients with extensive calcifications of the left atrial wall and mitral valvular disease, has been reported. Seven patients underwent to prosthetic replacement of the mitral valve and one to prosthetic replacement of the mitral and aortic valve. Beside the valvular replacement, the authors stress the importance of the surgical removal of the atrium wall calcifications, in order to avoid the postoperative haemorrhagic and embolic complications.
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Ten patients between 8 months and 9 years of age (average 4.3 years) underwent surgical relief of coarctation of the aorta by the technique of left subclavian flap aortoplasty. Before operation, nine patients had systolic hypertension in the upper extremity (average 145 mm Hg) and all had a significant pressure gradient across the coarctated aortic segment (average 45 mm Hg). The hospital and late mortality were zero. The follow-up over 7 years has shown complete relief of the coarctation and no ischemic impairment or functional limitation of the left upper extremity. The blood pressure returned to normal in all patients. Hemodynamic and angiographic studies, performed in one case, demonstrated adequate growth of the repaired segment and absence of a pressure gradient across the previously narrowed area. The time interval between the peak of the femoral pulse and the dicrotic notch of the carotid pulse, recorded postoperatively, was normal. We consider the left subclavian flap technique to be the operation of choice in infancy and also in older children, whenever the anatomic configuration of the coarctation suggests that subsequent growth would be severely restricted if other techniques were used.
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Eleven children with coarctation of the aorta were investigated before and after surgical treatment, using simultaneous indirect carotid and femoral pulse wave tracing. The timing of the onset of the femoral pulse in the children with coarctation, both before and after operation, did not differ significantly from normal. However, the time interval between the peak of the femoral pulse and the dicrotic notch of the carotid pulse was significantly shorter than normal in the children with coarctation before operation. After operation, the peak femoral to carotid dicrotic notch time interval was restored to normal. It is suggested that this simple non-invasive test might be of value in the long-term follow-up of patients after operation for coarctation of the aorta, particularly in those undergoing operation early in childhood, to detect residual or recurrent coarctation.