PubMed Health⌕ Search

Biomedical subjects

R Ferreira

Publications and source records attributed to R Ferreira.

At least 19 recordsLinked to original sources
PubMed1992

Reduction of reperfusion injury with preoperative rapid intravenous infusion of taurine during myocardial revascularization.

To assess a possible free-radical scavenging action of taurine during coronary artery bypass grafting, 12 patients were randomly divided into two equal groups. One to 3 hours before surgery, they received a rapid intravenous infusion of either placebo (group 1) or taurine (5 gm) (group 2). During surgery, biopsy samples were taken before ischemia (preischemic samples) and after 10 minutes of reperfusion (reperfusion samples). Lipoperoxidation was determined by hydroperoxide-initiated chemiluminescence of heart homogenates, and myocardial cell damage was assessed by electron microscopy. The values for chemiluminescence in preischemic and reperfusion samples from group 1 were 7500 +/- 1600 and 18,600 +/- 4600 cpm/mg of protein, respectively (p less than 0.03). This difference was not observed in group 2 where the values were 10,050 +/- 2700 and 11,800 +/- 4200 cpm/mg of protein, for preischemic and reperfusion samples, respectively. The number of severely damaged mitochondria (grades 3 and 4) in reperfusion samples from group 1 increased significantly compared to preischemic samples (25 +/- 8% vs 12 +/- 3%, p less than 0.01). Conversely no differences were observed between the number of severely damaged mitochondria in reperfusion and preischemic samples from group 2 (8 +/- 3% vs 8 +/- 2%). The number of damaged and necrotic myocytes increased in group 1 after reperfusion from 22 +/- 9% to 34 +/- 10% (p less than 0.03) and from 10 +/- 7% to 26 +/- 20% (p = NS), respectively. No changes were observed between reperfusion and preischemic samples in group 2. Treatment with taurine seems to reduce lipoperoxidation and decrease cell damage at the time of reperfusion.

Biopsy↗
PubMed1992

The hypertrophied myocardium and coronary disease. Structural changes in patients submitted to aortocoronary bypass surgery.

Seventeen patients with coronary disease submitted to myocardial revascularization were studied. Ten patients had a hypertrophied ventricle, and 7 had normal ventricular mass. Myocardial biopsies were obtained before ischemia and at the time of reperfusion and were assessed for: volume fraction of fibrous tissue, myocyte diameter, morphometric mitochondrial studies and ultrastructural changes. The volume fraction of fibrous tissue in patients with hypertrophied ventricle was 1.9 +/- 0.04, and in patients with normal ventricular mass was 0.9 +/- 0.01 (p less than 0.05). The diameter of the myocyte was 23 +/- 0.3 microns and 18 +/- 1.2 microns for patients with hypertrophied and normal ventricular mass, respectively (p less than 0.01). The value of volumetric density for pre-ischemia samples in patients with a hypertrophied ventricle was 23 +/- 2.2 and in patients with normal ventricular mass was 35 +/- 2.7 (p less than 0.02). Grades 3 and 4 of damaged mitochondria were significantly increased in reperfusion samples from patients with a hypertrophied ventricle compared to pre-ischemia samples. Collagen growth was increased in hypertrophied hearts which were also more sensitive to the ischemia/reperfusion mechanism.

Biopsy↗
PubMed1992

Effects of cloricromene on ischemia-reperfusion myocardial damage in the rabbit.

Cloricromene, a compound with several biological activities which suggest a therapeutic role in thrombosis or ischemic disease, has been studied for its effects on the extension of myocardial damage and the production of oxygen free radicals during periods of ischemia and reperfusion. In twenty rabbits the left anterior descending coronary artery (LAD) was occluded and cloricromene (3.6 micrograms/kg/min; n = 10) or placebo (n = 10) were continuously infused. After 50 min the artery was reopened and after 20 min of reperfusion a biopsy was obtained from the anterior wall of the heart in the LAD area and from the posterior wall (control myocardium) prior to sacrifice. Both samples were used for chemiluminescence measurement (free-radical production) and ultrastructural studies. In the placebo group all rabbits showed ST-segment changes during ischemia and reperfusion arrhythmias, while in the cloricromene group there were transient ST elevations in 4 animals which reverted at higher infusion rates of the drug. The chemiluminescence values were 18,017 +/- 1,956 and 8,583 +/- 918 cpm/mg protein (p < 0.001) in the anterior and posterior walls of the left ventricle, respectively, for the placebo group, and 7,767 +/- 992 and 8,333 +/- 832 cpm/mg protein (NS), respectively, for the cloricromene group. The ratio between the anterior and posterior wall was 2.27 +/- 0.37 for the placebo group versus 0.95 +/- 0.11 for the cloricromene group (p < 0.001). In ultrastructural studies, the anterior wall in the placebo group showed irreversible myocyte injury and infarction as well as mitochondrial damage. Samples from the cloricromene-treated group showed, in general, preservation of myocyte architecture or minor signs of injury. These results illustrate clearly the protective effect of cloricromene during damage induced by ischemia and reperfusion in the rabbit.

Animals↗
PubMed1992

Coronariographic significance of heart rate variation related to ischemic episodes in patients undergoing peripheral vascular surgery.

OBJECTIVES: To evaluate the characteristics of myocardial ischemia during daily life and their coronariographic significance in a group of patients with proven coronary artery disease undergoing peripheral vascular surgery. SETTING: Department of Cardiology--Central Hospital--Lisbon. METHODS: In 14 patients undergoing peripheral vascular surgery and in whom coronariography revealed coronary significative lesions, Holter monitoring was performed during a 24-hour period. Two groups of ischemic episodes were considered: Group A constituted by 44 episodes detected in patients with left main or three vessel disease and group B by 12 episodes detected in patients with one ot two vessel disease. In each group the ischemic parameters were studied. RESULT: The incidence of myocardial ischemia was 64%. Statistically significant differences were observed between group A and B concerning the mean heart rate variation from two minutes before the onset of ST-segment depression to its onset (2.39 bpm vs 8.75 bpm; p < 0.05), from the onset of ST-segment depression to its maximal depression (4.43 bpm vs 16.67 bpm; p < 0.001) and from two minutes before St-segment depression to its maximal depression (6.82 bpm vs 25.4 bpm; p < 0.00001). No differences were found in duration and maximal ST-segment depression. CONCLUSION: Particular characteristics of heart rate variation related to the ischemic episodes seem to have a relation with the severity of coronary artery disease in patients undergoing peripheral vascular surgery.

Aged↗
PubMed1992

Functional significance of premature ventricular complex morphology evaluated during treadmill exercise stress test in patients with coronary artery disease.

OBJECTIVES: To evaluate the relation between premature ventricular complexes morphology and left ventricular myocardial systolic function in patients with proved coronary artery disease. SETTING: Department of Cardiology at General Hospital. METHODS: From 112 patients (pts) with proved coronary artery disease, thirty-three pts with premature ventricular complexes (PVC) detected during treadmill exercise stress test were selected. Two groups of pts were considered: group I-20 pts with regular contour or with a narrow notching (< 40 ms; type I PVC) and group II-13 patients with wide notching (> 40 ms; type II PVC). In each group the following parameters were studied: ejection fraction, QRS duration, duration of exercise, number of metabolic units and the prevalence of ventricular aneurysm and mitral regurgitation. RESULTS: Statistical significant differences were found between group I and II concerning the mean ejection fraction (59.2% vs 48.6%; p < 0.05). The prevalence of ventricular aneurysm and mitral regurgitation was higher in patients with type II ventricular premature complexes (10% vs 30%). CONCLUSION: Particular characteristics of premature ventricular complexes detected during treadmill exercise stress test, in patients with proved coronary artery disease, suggest the presence of left ventricular myocardial systolic dysfunction.

Coronary Disease↗
PubMed1992

[What is the value of myocardial perfusion studies with isotopes in patients with complete left bundle branch block?].

The prognosis of left bundle branch block is determined by associated cardiovascular disease. Exercise electrocardiography is not helpful in detecting ischemia in these patients. Exercise thallium-201 scintigraphy has been widely accepted for that purpose. The authors made an overview of several studies suggesting that exercise thallium-201 scintigraphy has low specificity regarding left anterior descending coronary artery disease. They also review the mechanisms of perfusion defects in patients with left bundle branch block without coronary artery disease. One important question to be clarified is weather small defects are unrelated to coronary artery disease. Finally the authors analyse a few methods to increase diagnostic accuracy of perfusion scintigraphy in left bundle branch block. First the employment of a new criterium that requires the apex to be abnormal to indicate left anterior descendent artery disease. Second Pharmacological Stress with Dipyridamole or Adenosine. Third imaging with Tc-99m-MIBI.

Adenosine↗
PubMed1992

[Peri-ungual capillaroscopy in atherosclerosis].

The pathology of the major vessels also affects microcirculation, making possible to evaluate at the distal sector the consequences of an ischaemia, due to an artery disease, for instance. This work had as its main aim to evaluate by peri-ungueal capillaroscopy (PUC) the lesions due to an atherosclerotic process and the prognosis and/or diagnosis value of this exam. We studied 210 patients with either risk factors for atherosclerosis or atherosclerotic disease, who were divided into groups according to the severity of the lesions seen in PUC. Finally, we were able to conclude that although the capillaroscopic lesions found are not specific, they appear very early in the process and are more serious in the more severe cases.

Adolescent↗
PubMed1992

[Role of pharmacologic stimulation with myocardial perfusion scintigraphy in the evaluation of patients with ischemic cardiopathy].

Exercise myocardial-thallium scintigraphy plays a fundamental role in the diagnosis of coronary artery disease. Once exercise is not always feasible, pharmacological stress became a possible alternative. The authors review the mechanism of action, administrations protocols, indications and side effects of the drugs used for this purpose: dipyridamole, adenosine and dobutamine. Dipyridamole causes coronary hyperemia by increasing the interstitial levels of endogenous adenosine. Perfusion defects result from the mismatch of coronary reserve in different coronary territories. The drug administration is classically performed with a 0.142 mg/kg/min dosage e.v. for 4 minutes, total of 0.56 mg/kg. It is possible to use a greater dose of 0.84 mg/kg e.v. for 10 minutes, increasing sensitivity without loss of specificity for diagnosis of coronary artery disease. Oral dipyridamole protocols with 300 and 400 mg were used with similar results for sensitivity and specificity. The oral protocol has the disadvantage of delayed onset and longer action. Including several dipyridamole studies, 87% was obtained for sensitivity and 84% for specificity, in the diagnosis of CAD. Dipyridamole scintigraphy has been applied to myocardial infarction risk stratification, cardiac risk evaluation of patients proposed to noncardiac surgery and therapeutic efficacy evaluation of reperfusion techniques (angioplasty and surgery). The secondary effects of dipyridamole are frequent, however mild and well tolerated. They occur in half the patients, the most frequent, facial flushing (2%), dizziness (5%), nausea (4%), vomiting (1%), headaches (11%) and chest pain (26%). Some important complications were reported although rare: myocardial infarction, ventricular fibrillation and bronchospasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1992

[Annuloaortic ectasia: report of a case].

The authors describe a case of a patient with annuloaortic ectasia (AAE) and severe aortic regurgitation. The diagnostic was made by angiography. He was submitted to a Bentall's procedure; replacement of the ascending aorta by a conduit and of aortic valve by a mechanical prosthesis with reimplantation of coronary arteries into the conduit. The only complication was atrial fibrillation with fast ventricular response. Nowadays he is clinically well, in NYHA class I. The authors make some considerations about AAE, its surgical treatment and its results.

Aortic Diseases↗
PubMed1992

Reduction of myocardial damage by cloricromene during ischemia-reperfusion in the rabbit.

We studied the effect of cloricromene on myocardial damage during ischemia and reperfusion. The left anterior descending coronary artery was occluded in 20 rabbits and cloricromene (6.2 micrograms/kg/min) (n = 10) or placebo (n = 10) were continuously infused. After 10 minutes of occlusion, a first biopsy was obtained from the apex. After 30 minutes, the artery was reopened and after 10 minutes a second biopsy was taken. Both samples were used for chemiluminescence and electron microscopy. The group given placebo showed displacement of the ST segment throughout the ischemic period and arrhythmias during reperfusion; while, in the group given cloricromene, there were transient ST segment elevations in 5 animals, which reverted as the infusion was increased. The chemiluminescence values were 7100 +/- 1300 cpm/mg protein and 14900 +/- 2300 (p less than 0.01) for the first and second biopsies of the control group and 5900 +/- 900 and 6100 +/- 900 (NS) for the first and second biopsies of the cloricromene-treated group. In the group given placebo, the second biopsy showed early signs of irreversible myocyte injury and infarction, whereas samples from the group given cloricromene showed a preservation of myocyte architecture. During ischemia, the percentage of normal mitochondria was lower in the placebo group (p less than 0.0001); and, on reperfusion, the percentage of severely damaged mitochondria was increased in the placebo group (p less than 0.0001). The direct addition of cloricromene in vitro to myocardial homogenates did not reduce hydroperoxide-induced chemiluminescence.

Animals↗
PubMed1991

The value of the echo-Doppler in cardiomyoplasty procedures.

UNLABELLED: Echo-Doppler determinations were performed in patients submitted to cardiomyoplasty procedure using the latissimus dorsi muscle graft (LDMG). In four patients who had 1 year of follow-up or more the left ventricular internal dimension in diastole (LVIDd), left ventricular internal dimension in systole (LVIDs), septal-E point separation (E-septum), distance of the mitral valve (E-E'), maximal aortic cuspid separation (MACS) and left atrium dimension (LA) were determined by two-dimensional echocardiogram. With a pulsed Doppler in the aortic root the following parameters were obtained: aortic peak flow (AoPF), velocity time integral (VTI), and ejection period (EP). With the stimulator on, the determinations were done using a ventricle muscle (VM) delay of 25, 75, and 250 msec. RESULTS: No significant differences were observed by Echo determinations between the stimulator off and on. With the supporting contraction of the LDMG the best hemodynamic performance was obtained when the VM delay ranged between 75 and 250 msec. Values with the stimulator off and on were as follows: AoPF: 90.8 +/- 8 cm/sec and 104.5 +/- 9 cm/sec; VTI: 14.8 +/- 2 cm and 19.2 +/- 2 cm; EP: 230 +/- 10 msec and 245 +/- 20 msec. A decrease in the systolic pressure of the pulmonary artery and a decreased functional regurgitation of the mitral and tricuspid valve were observed in the follow-up determinations. All patients showed restricted mitral flows that remained unchanged during the follow-up. CONCLUSIONS: In this group of patients the echo-Doppler showed an improvement of the systolic function of the left ventricle when it is supported by the LDMG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Antithrombin III. Physiologic, physiopathologic and laboratory aspects].

Hemostatic control is based in a delicate balance between the activities of activator enzymes and their inhibitors, each one depending on a large number of proteins. Plasma Antithrombin III (ATIII) is one of the most important coagulation inhibitors and the fundamental enzyme for the therapeutical action of heparin. In the last years it was well established that ATIII deficiency accounts for a thrombotic state and inefficiency of heparin therapy. In this work, the authors review the biology of ATIII including its biochemical nature, its physiology, physiopathology and mechanism of action, analysing the implications of its deficiency. The authors draw the attention on clinical and laboratory studies that analyse the prevalence and importance of congenital and acquired deficiency of ATIII, in relation to the prevalence of venous thrombosis. Finally, the laboratory methods applied to the study of ATIII and to the biological control of heparin therapy are described with emphasis on the importance of the ATIII concentrates on this type of treatment. Also the fundamental aspects of heparin resistance are specially mentioned.

Antithrombin III↗
PubMed1991

Incidence, characteristics and coronariographic significance of myocardial ischemia during daily life in patients with angina pectoris.

OBJECTIVES: To evaluate the incidence, characteristics and angiographic significance of myocardial ischemia detected on Holter monitoring in a group of patients with stable angina pectoris. SETTING: Department of Cardiology of a Central Terciary Hospital. METHODS: In 24 patients (pts) with stable angina pectoris and proven coronary artery disease (11 pts with left main or three vessel disease; 13 pts with one or two vessel disease), a 24 hour Holter monitoring was performed. Two groups of ischemic episodes were considered: Group I with 65 ischemic episodes detected in pts with left main or three vessel disease and group II constituted by 17 ischemic episodes detected in pts with one or two vessel disease. RESULTS: The incidence of myocardial ischemia was 91% in pts with left main or three vessel disease and 46% in pts with one or two vessel disease. Statistically significant differences were seen between group I and II concerning the mean heart rate variation from two minutes before onset of ST-segment depression to its onset (3.5 bpm vs 7.4 bpm; p less than 0.05) and from the onset of ST-segment depression to its maximal depression (6.5 bpm vs 15 bpm; p less than 0.000001). CONCLUSIONS: The presence of myocardial ischemia and some of its characteristics on Holter monitoring seem to have a relation with the severity of coronary artery disease in patients with stable angina pectoris.

Activities of Daily Living↗