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Biomedical subjects

W V Vicente

Publications and source records attributed to W V Vicente.

At least 19 recordsLinked to original sources
PubMed2001

Submitral left ventricular aneurysm. Case report and review of published Brazilian cases.

Submitral left ventricular aneurysm is a cardiac pathology widely recognized, but relatively unknown, occurred almost exclusively in African black patients. Although still this idea of racial prevalence exists, cases have been described in patients of all the races. Ten Brazilian cases were reported. One of them was presented inside an Italian paper that refers the surgical treatment of a Brazilian patient of black race. We reported one more submitral left ventricular aneurysm case in a brown female patient, with antecedents of peripheral thromboembolism initially not identified as consequence of the cardiac pathology.

Female↗
PubMed1999

Intermittent anterograde normothermic blood cardioplegia: experimental study in rabbits.

BACKGROUND: We investigated the degree of myocardial protection provided by intermittent anterograde normothermic blood cardioplegia infusion for 60 minutes at 37 degrees C in normal rabbit hearts. METHODS: Thirty-two New Zealand rabbits were studied and divided into two groups: experimental group and control group. In the experimental group, normothermic blood cardioplegia was infused into the aortic root every 20 minutes over a one-hour period using a two-minute infusion dose. This amounted to an ischemic (unperfused) time of 52 minutes (or 86.6% of the total time). The biochemical investigation was carried out in two phases; Phase I: metabolic study after ischemia with no reperfusion and Phase II: metabolic and functional study after reperfusion. Reperfusion was carried out using a parabiotic perfusion system. Myocardial glycogen and mitochondrial respiration in the ventricular myocardium were established immediately after the end of intermittent cardioplegic solution infusion (Phase I) and after blood reperfusion (Phase II), when left ventricular function (dP/dt max) was also evaluated. RESULTS: At the end of Phase I, there was a significant decrease in myocardial glycogen levels to 58% compared with the control group. In Phase II, the differences in myocardial glycogen between the experimental and the control group were not significant. Mitochondrial respiration analysis did not show significant differences between the experimental and control groups, either in Phase I or II. In Phase I, dP/dtmax values were 903.39 +/- 113.46 mmHg/sec and 1,043 +/- 256.94 mmHg/sec for the experimental and control group, respectively. These differences were not statistically significant. CONCLUSIONS: Intermittent anterograde blood cardioplegia infusion every 20 minutes for 60 minutes at 37 degrees C was an effective myocardial protection method in normal rabbit hearts.

Animals↗
PubMed1996

Coronary vascular regulation during postcardioplegia reperfusion.

BACKGROUND: This study extends previous investigations of global and regional myocardial blood flow during early postcardioplegia reperfusion. The hypothesis tested is that coronary vascular regulation becomes abnormal within 3 minutes after the start of postcardioplegia reperfusion. METHODS: Pigs (n = 40) were supported by cardiopulmonary bypass and 38 degrees C blood cardioplegic solution was infused. A control preischemic microsphere injection (No. 1) was given in asystolic hearts. Groups 1 to 3 had 1 hour of hypothermic cardioplegic arrest. Group 4 (control group) had 1 hour of perfusion without cardioplegia. A blood cardioplegic solution at 38 degrees C and 70 mm Hg pressure was infused to maintain asystole during the initial 7 to 10 minutes of reperfusion in all groups. Left ventricular intracavitary pressures were set at 0, 10, 20, or 0 mm Hg in groups 1, 2, 3, and 4 (n = 10 pigs per group), respectively, during the initial 7 minutes of reperfusion. The ventricle was then decompressed. At 30 seconds, 3 minutes, and 6 minutes after reperfusion, microsphere injections 2, 3, and 4 were given in asystolic hearts. Microsphere injection No. 5 was given 10 minutes after reperfusion in beating vented hearts. RESULTS: (1) Left ventricular distention during the initial 7 minutes of reperfusion after hypothermic cardioplegic arrest attenuates postischemic hyperemia. (2) Left ventricular intracavitary pressure of 20 mm Hg during reperfusion causes a decrease in endocardial blood flow relative to epicardial blood flow at 6 minutes after reperfusion. (3) Global myocardial blood flow during postcardioplegia reperfusion falls significantly below preischemic control values despite the return of electromechanical activity. INFERENCE: Coronary vascular regulation (i.e., coronary resistance and metabolic flow recruitment) becomes abnormal within 3 minutes after the start of reperfusion after hypothermic blood cardioplegic arrest.

Animals↗
PubMed1996

[Complete heart block after percutaneous mitral valvotomy with Inoue balloon].

We report a permanent complete heart block, in a 27 year-old female patient, developed during mitral percutaneous valvotomy using a single inflation of the Inoue balloon catheter. After one month, even using corticoids, a Mobitz II second-degree atrioventricular block persisted, the patient became symptomatic to moderate efforts and a cardiac pacemaker was implanted.

Adult↗
PubMed1996

[Intrapericardial teratoma. A case report and a literature review].

A case of newborn intrapericardial teratoma is reported. The clinical, echocardiographic, tomographic and histologic features are described, and also, the therapeutic options. The newborn was submitted to surgical excision of the intrapericardial tumor and has a clinical follow-up greater than four years.

Follow-Up Studies↗
PubMed1995

Tissue oxygenation with graded dissolved oxygen delivery during cardiopulmonary bypass.

BACKGROUND: Intravascular perfluorochemical emulsions together with a high oxygen tension may increase the delivery of dissolved oxygen to useful levels. The hypothesis of this study is that increasing the dissolved oxygen content of blood with incremental doses of a perfluorochemical emulsion improves tissue oxygenation during cardiopulmonary bypass in a dose-related fashion. METHODS AND RESULTS: Oxygen utilization was studied in a profoundly anemic canine model of hypothermic cardiopulmonary bypass. Forty-two dogs underwent normovolemic hemodilution to a hematocrit of 15.8% +/- 0.6% (mean +/- standard error of the mean). Cardiopulmonary bypass was begun and resulted in a hematocrit of 9.4% +/- 0.6%. A standard priming solution was used in the control group (n = 12), and the test groups received 1.35 gm perfluorochemical.kg-1 (n = 10 dogs), 2.7 gm perfluorochemical.kg-1 (n = 10 dogs), or 5.4 gm perfluorochemical.kg-1 (n = 10 dogs) through the venous return cannula. Each animal underwent a series of randomized pump flows (0.25, 0.5, 1.0, 1.5, 2.0, and 3.0 L.min-1.m-2) at 32 degrees C. After the randomized flows were completed at 32 degrees C, the temperature was raised to 38 degrees C and cardiopulmonary bypass was discontinued. Mortality from cardiac failure on separation from cardiopulmonary bypass was 42% in the control group and 20% in perfluorochemical-treated groups. The mean perfluorochemical dose was higher in survivors than in nonsurvivors (2.9 +/- 0.4 versus 1.3 +/- 0.5 gm perfluorochemical.kg-1; p < 0.05). No differences in oxygen consumption or transbody lactate gradient were found between groups during cardiopulmonary bypass. Analysis of mixed venous oxygen tension (a surrogate measure for tissue oxygenation) as a function of cardiopulmonary bypass flow normalized to body surface area showed that the control group had significantly lower mixed venous oxygen tension (p < 0.05) than the perfluorochemical emulsion-treated groups. Furthermore, the differences were related to the perfluorochemical emulsion dose. These differences in mixed venous oxygen tension continued after termination of cardiopulmonary bypass. The coronary sinus oxygen tension and cardiac arterial-venous oxygen content differences during and after cardiopulmonary bypass were similar among the control and perfluorochemical emulsion-treated animals. Dissolved oxygen consumption during and after cardiopulmonary bypass was calculated. Dissolved oxygen consumption increased in the perfluorochemical-treated animals in a perfluorochemical dose-related manner and was significantly higher in perfluorochemical-treated animals than in the control animals (p < 0.05). CONCLUSIONS: Graded increases in mixed venous oxygen tension during cardiopulmonary bypass were observed in response to graded increases in the dissolved oxygen delivery. These data suggest that enhancing oxygenation with perfluorochemical-dissolved oxygen is an effective temporary substitute for the use of hemoglobin-bound oxygen during cardiopulmonary bypass. Perfluorochemical-dissolved oxygen may be particularly beneficial in the setting of multiple hypoxic stresses.

Analysis of Variance↗
PubMed1994

Effect of postcardioplegia reperfusion rhythm on myocardial blood flow.

This study compared myocardial blood flow during postcardioplegia reperfusion asystole and ventricular fibrillation. Pigs (n = 20) were placed on cardiopulmonary bypass and blood cardioplegic solution at 38 degrees C was then infused. A preischemia microsphere injection was given in asystolic hearts. All animals then had 1 hour of hypothermic cardioplegic arrest and underwent reperfusion with high-dose (n = 10) or low-dose (n = 10) 38 degrees C blood cardioplegia. At 30 seconds after reperfusion, all hearts were asystolic. The second microsphere injection was then given. At 3 and 6 minutes after reperfusion, the animals' hearts were either in asystole (n = 10) or ventricular fibrillation (n = 10), and the third and fourth microsphere injections were then given. At 10 minutes after reperfusion, all hearts were beating and the final (fifth) microsphere injection was given. There was an initial increase in the global myocardial blood flow during reperfusion versus the preischemic control value. However, later, during reperfusion (ie, at the third and fourth injections), there was a significant (p < 0.05) decrease in the global myocardial blood flow. There was no discernible response in either the global myocardial blood flow or regional myocardial blood flow distribution to electromechanical activity (ie, ventricular fibrillation) for the third and fourth injections, suggesting that coronary autoregulation was abnormal. Postcardioplegia reperfusion ventricular fibrillation imposes metabolic demands that may cause reperfusion injury, especially in hearts affected by hypertrophy, ventricular distention, or coronary obstruction.

Animals↗
PubMed1994

Use of current generation perfluorocarbon emulsions in cardiac surgery.

The development of novel perfluorocarbon emulsions that contain higher concentrations of perfluorochemicals than previous emulsions has renewed interest in the use of this class of erythrocyte substitute in cardiopulmonary bypass (CPB). Perfluorocarbons have the potential to increase the oxygen content of the perfusate and thus increase the capacity of the heart-lung machine to deliver oxygen to the body during CPB. Increasing the capacity of the heart-lung machine to deliver oxygen to the body has important implications for the conduct of cardiac operations. For example, adding perfluorocarbons to the pump prime solution may allow larger volumes of blood to be withdrawn from the patient immediately prior to bypass for transfusion after bypass. Lowering the acceptable hematocrit during CPB with the use of perfluorocarbons may also decrease the need for homologous transfusions of erythrocytes in neonates or anemic adults who undergo CPB.

Blood Substitutes↗
PubMed1994

Effect of hemoglobin concentration on oxyhemoglobin dissociation during hypothermic blood cardioplegic arrest.

BACKGROUND: This study compares oxyhemoglobin dissociation during the nonperfused periods of hypothermic cardioplegic arrest in two blood cardioplegic solutions with different hemoglobin concentrations. The hypothesis is that more oxygen will dissociate from hemoglobin in a blood cardioplegic solution with a higher hemoglobin content than from a cardioplegic solution with a lower hemoglobin content. However, the increment in the volume of oxygen that dissociates from hemoglobin will be less than anticipated by a ratio of hemoglobin concentrations in the cardioplegic solution. METHODS AND RESULTS: Pigs (n = 22) were supported by bypass and subjected to 60 minutes of hypothermic cardioplegic arrest with either a high-hemoglobin (n = 10) or low-hemoglobin (n = 12) blood cardioplegic solution. Aortic root and coronary sinus blood samples were obtained before bypass and 5 seconds after the start of cardioplegic infusions at 20, 40, and 60 minutes of cardioplegic arrest. Oxyhemoglobin dissociation occurred in both experimental groups during the ischemic intervals of cardioplegic arrest. However, there were no significant differences between the high- and low-hemoglobin groups in the arterial-venous oxygen content differences for samples taken after each of the three ischemic intervals (p values: control = 0.78; cardioplegia interval 1 = 0.95; interval 2 = 0.56; and interval 3 = 0.12). CONCLUSIONS: The present study emphasizes the inherent limitations of unmodified erythrocyte hemoglobin as an oxygen source in hypothermic alkalotic cardioplegic solutions. These limitations may be obviated by methods that increase the dissolved oxygen content of the cardioplegic solution or methods that decrease the affinity of hemoglobin for oxygen under conditions of hypothermia and alkalosis.

Animals↗
PubMed1994

Electrophysiological mechanisms for postcardioplegia reperfusion ventricular fibrillation.

BACKGROUND: Reperfusion arrhythmias that follow regional ischemia at normothermia have been studied extensively and are considered to be a manifestation of ischemia-reperfusion injury. In contrast, reperfusion arrhythmias that occur following hypothermic cardioplegic arrest have received little attention from investigators. This study defines the electrophysiological mechanisms for postcardioplegia reperfusion ventricular fibrillation (RVF). METHODS AND RESULTS: The electrophysiology of postcardioplegia RVF was examined by using in situ porcine hearts. Complete heart block was created by using cryoablation before cardioplegic arrest so that isolated ventricular electrical activity could be observed for a prolonged time after reperfusion. Electrophysiological data were collected from limb leads, right atrial electrodes, and left ventricular electrodes in all 12 pigs. In 5 pigs, right and left ventricular endocardial electrograms were also recorded. A total of 103 episodes of RVF were analyzed. In 90 instances, an accelerating automatic ventricular focus initiated RVF. In five animals, RVF occurred after ventricular pacing (ie, purely re-entrant RVF). The mechanism for RVF was indeterminant in 8 instances. The origin of RVF was mapped in 44 instances. RVF usually originated in the left ventricle (25 instances) or septum (16 instances). CONCLUSIONS: Enhanced automaticity and re-entry are the mechanisms for postcardioplegia and regional ischemia-reperfusion arrhythmias. This finding supports the use of postcardioplegia RVF as a variable for comparing strategies for myocardial protection and suggests that information generated by the study of regional ischemia reperfusion arrhythmias can be used to understand postcardioplegia reperfusion arrhythmias and ischemia-reperfusion injury.

Animals↗
PubMed1993

Use of the platysma myocutaneous flap for cervical trachea reconstruction: an experimental study in dogs.

Cervical trachea reconstruction with a non-stented platysma myocutaneous door flap (NPMCF) was studied in 23 dogs. Window defects involving 5, 10, or 15 rings and the whole anterior tracheal wall were produced in 3 different groups of animals. A segmentary defect involving the resection of 3 tracheal rings but preserving the posterior membranous wall was created in another group. The results were evaluated by clinical follow-up of up to 100 days, by tracheoscopy 1 week after surgery, and by macroscopic and microscopic examination after the animals' natural death or sacrifice. The NPMCF proved to be adequate for the reconstruction of window defects limited to 5 and 10 rings, with success rates of 100% and 75%, respectively. The use of the NPMCF for tracheal reconstruction had the following main advantages: 1. relatively simple, easy, and expeditious surgery; 2. use of a single operative field; 3. availability of large amounts of donor tissue; 4. adequate thickness; 5. reliable irrigation; 6. resistance to environmental exposure as evidenced by absence of infection; and 7. 100% take rate with no granulomas or scar stenosis at the suture lines. However, luminal occlusion due to flap collapse was a 100% fatal complication when the NPMCP was used either for reconstruction of larger window tracheal defects (15 rings-group 3) or segmentary defects (group 4); this was the main limitation of the method, followed by hair growth with accumulation of secretions, which can be easily dealt with. It can be anticipated that this method has a potential for application in well-selected patients.

Animals↗
PubMed1992

The effect of proximal gastric vagotomy plus duodenoplasty on duodenogastric reflux.

Alkaline reflux gastritis is a clinical syndrome that results from a mucosal injury by duodenal contents. In this study, the amount of duodenogastric reflux was assessed in patients who previously underwent proximal gastric vagotomy (PGV group; n = 11) and PGV plus duodenoplasty (PGV+D group; n = 10) as a treatment for duodenal ulcer. The control group (A) consisted of 11 healthy volunteers without endoscopic abnormalities. A quantitative index of duodenogastric reflux was obtained in each case by determining the percentage of the injected dose of 99mTechnetium-DISIDA that was recovered by continuous aspiration of gastric juice in fasting subjects. In the PGV group, the percentage of administered 99mTechnetium-DISIDA recovered from the stomach (median: 0.69%; range: 0.09%-3.61%) did not differ significantly (P > 0.05) from that of the PGV+D group (median: 0.49%; range: 0.09%-3.91%) and from that of the A group (median: 1.47%; range: 0.22%-3.01%). The results show that proximal gastric vagotomy plus duodenoplasty did not increase duodenogastric reflux.

Duodenal Ulcer↗
PubMed1991

Acquired aorto-coronary vein fistula after bypass graft surgery: report of two cases with long-term follow-up.

Two patients who underwent bypass surgery with saphenous grafts had a fistula resulting from inadvertent grafting of the cardiac vein correspondent to a targeted diagonal artery. Hemodynamic effects at rest were restricted to moderate elevation of the pulmonary blood flow, by 23 and 13% respectively, at 5 and 12 months postoperatively. No objective signs of ischemia could be elicited in either patient, in the fistula related region, and left ventricular function remained within normal limits in both cases throughout the follow-up period (36 and 24 months, respectively).

Aged↗
PubMed1991

[Surgical treatment of dysphagia lusória].

Two cases of this anomaly, in women (26 and 49 years old), with symptoms of short duration (4 and 3 months) of dysphagia, regurgitation and esophagitis, without loss of weight, are presented. In both, the final diagnosis was made by mean of thoracic aortogram. Esophagoscopy realized only in the first patient, demonstrated the pulsatile esophageal compression. The first patient was operated on through a right cervical incision, made in the anterior border of the sternomastoid muscle. In the second, a partial sternotomy, combined with a right supraclavicular prolongation, was used. In both, the anomalous artery was taken from the aorta and behind the esophagus, and anastomosed to the right common carotid artery. The dysphagia disappeared in the second case, but persisted attenuated, in the first one. Manometric studies realized in the 3rd and 18th months postoperatively demonstrated an aperistaltic segment of the esophagus (between 4 and 7 cm from the superior sphincter).

Adult↗
PubMed1983

Impairment of baroreflex control of the sinoatrial node after cardiac operations with extracorporeal circulation in man.

The sensitivity of the baroreceptor reflex to transient hypertension was determined in 13 patients before (control) and after (72 hours) open cardiac operations with extracorporeal circulation (ECC). In all patients early postoperative values were appreciably decreased (p less than 0.01) as compared to the preoperative values. This decrease suggested severe impairment of baroreflex control of the sinoatrial node. These changes were not correlated with concurrent alterations in heart rate or systemic arterial, left atrial, or right atrial pressures. In addition, respiratory sinus node arrhythmia was absent in all subjects. In four patients, subsequent studies 4, 8, 10, and 12 months, respectively, after the operation revealed good recovery of baroreflex sensitivity and respiratory influences on beat-to-beat variation. No similar effects were observed in two patients studied before and after cardiac operations without ECC. It is possible that direct trauma to the nervous supply of the sinoatrial node is a major factor in that reversible dysfunction; in fact, in three patients evidence was obtained that while sinoatrial node responses were impaired, the reflex control of the atrioventricular region remained unaltered. These findings point to further impairment of the fine control of heart rate imposed by the conditions of cardiac operations with ECC in patients with previously curtailed cardiac reserve.

Adolescent↗