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Biomedical subjects

M D Cerqueira

Publications and source records attributed to M D Cerqueira.

At least 73 records · Page 4Linked to original sources
PubMed1990

Myocardial Infarction Triage and Intervention Project--phase I: patient characteristics and feasibility of prehospital initiation of thrombolytic therapy.

Prehospital initiation of thrombolytic therapy by paramedics, if both feasible and safe, could considerably reduce the time to treatment and possibly decrease the extent of myocardial necrosis in patients with acute coronary thrombosis. Preliminary to a trial of such a treatment strategy, paramedics evaluated the characteristics of 2,472 patients with chest pain of presumed cardiac origin; 677 (27%) had suitable clinical findings consistent with possible acute myocardial infarction and no apparent risk of complication for potential thrombolytic drug treatment. Electrocardiograms (ECGs) of 522 of the 677 patients were transmitted by cellular telephone to a base station physician; 107 (21%) of the tracings showed evidence of ST segment elevation. Of the total 2,472 patients, 453 developed evidence of acute myocardial infarction in the hospital; 163 (36%) of the 453 had met the strict prehospital screening history and examination criteria and 105 (23.9%) showed ST elevation on the ECG and, thus, would have been suitable candidates for prehospital thrombolytic treatment if it had been available. The average time from the onset of chest pain to prehospital diagnosis was 72 +/- 52 min (median 52); this was 73 +/- 44 min (median 62) earlier than the time when thrombolytic treatment was later started in the hospital. Paramedic selection of appropriate patients for potential prehospital initiation of thrombolytic treatment is feasible with use of a directed checklist and cellular-transmitted ECG and saves time. This strategy may reduce the extent and complications of infarction compared with results that can be achieved in a hospital setting.

Adult↗
PubMed1990

Body fat distribution in healthy young and older men.

Central and/or intraabdominal (IA) fat is an independent predictor of obesity-related metabolic abnormalities in young and middle-aged subjects. The elderly are "fatter" at any given relative weight and often have similar metabolic abnormalities. In this study we compare body composition, circumferences, and specific fat depots areas in a population of healthy young and older men. Although the two groups were similar in body mass index and percent body fat, their distribution of adiposity was different. The young subjects had 16% and 10% larger thigh (p = .0001) and arm (p less than .01) circumferences respectively, while the ratio of waist-to-hip circumference was greater in the older subjects (0.93 +/- 0.04 vs 0.97 +/- 0.04, p = less than .01). The most striking differences between the groups were noted on computed tomography, with a twofold greater IA fat area (72.6 +/- 38.2 vs 143.6 +/- 56.2 cm2, p less than .0001), and a twofold lesser thigh subcutaneous fat area (156.3 +/- 69.3 vs 82.4 +/- 29.7 cm2, p less than .001) in the older subjects. We conclude there is an age-related central and intraabdominal redistribution of adipose mass, even in healthy older subjects. Since these changes occur in the absence of clinical disease, the associations between metabolic abnormalities and a central and or IA distribution of adiposity in the elderly must be investigated further.

Adipose Tissue↗
PubMed1990

Effect of exercise on insulin action, glucose tolerance, and insulin secretion in aging.

To assess the effect of exercise training on the insulin resistance and impaired pancreatic B-cell function of aging, we studied 13 healthy older men (ages 61-82 yr) before and after 6 mo intensive endurance exercise. An index of insulin sensitivity (SI) was measured using Bergman's minimal model. Intravenous glucose tolerance was quantified using the glucose disappearance constant (KGlc) while oral glucose tolerance was assessed after a 100-g glucose load. B-cell function was evaluated by measuring the acute insulin response (AIR) to glucose injection at fasting glucose (AIRGlc) and the AIR to arginine at multiple clamped glucose levels. Exercise produced an endurance training effect as demonstrated by an 18% increase in maximum O2 consumption (VO2max) [38.2 +/- 1.4 to 45.0 +/- 1.1 (SE) ml.kg fat-free mass-1.min-1, P less than 0.001]. An unchanged fasting glucose (5.3 +/- 0.2 to 5.4 +/- 0.2 mM) despite a reduced fasting insulin (61 +/- 6 to 48 +/- 6 pM, P less than 0.01) suggested exercise training improved insulin sensitivity. This was confirmed by a 36% increase in SI from 3.47 +/- 0.41 to 4.71 +/- 0.42 x 10(-5) min-1/pM (P = 0.01). Intravenous glucose tolerance did not change as measured by KGlc, which was 1.46 +/- 0.09 before and 1.48 +/- 0.16%/min after exercise training. Likewise, the incremental glucose response to oral glucose (633 +/- 49-618 +/- 45 mM.min) was unchanged. B-cell function was decreased as reflected by AIRGlc (351 +/- 73-245 +/- 53 pM, P less than 0.01) and the AIRArg at maximal glycemic potentiation (AIRmax, 1,718 +/- 260-1,228 +/- 191 pM, P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Fluoromisonidazole. A metabolic marker of myocyte hypoxia.

Fluoromisonidazole is metabolically trapped in viable hypoxic cells in vitro. This property is the basis for the hypothesis that [18F]fluoromisonidazole can be used to detect hypoxic tissues noninvasively using positron emission tomography. To assess the potential usefulness of this compound as a marker for hypoxic myocardium, we measured the accumulation of [3H]fluoromisonidazole in isolated adult rat myocytes under normoxic, hypoxic (5,000 ppm O2), and anoxic conditions. Both anoxia and hypoxia caused a marked increase in [3H]fluoromisonidazole accumulation. Relative to uptake during normoxia, uptake during anoxia was increased by 8.4-fold at 60 minutes and 26.5-fold at 180 minutes (p less than 0.001). During hypoxia, uptake was increased by 4.4-fold at 60 minutes and by 15.3-fold at 180 minutes (p less than 0.0001) and occurred in the absence of significant cell injury as measured by release of creatine kinase and changes in cell morphology. Additional studies demonstrated a slow oxygen-insensitive efflux of fluoromisonidazole or labeled metabolite(s) from myocytes reincubated in drug-free medium. We conclude that fluoromisonidazole is avidly retained in hypoxic myocytes and thus may be suitable for noninvasive detection of hypoxic myocardium using positron emission tomography.

Animals↗
PubMed1990

The role of preoperative radionuclide ventriculography in defining outcome after revascularization of the extremity.

Revascularization of the extremity was performed upon 110 patients after preoperative radionuclide ventriculography (RNVG). Mean ejection fraction (EF) was 50 +/- 13 per cent. Ventricular wall motion abnormalities were present in 46 per cent. Revascularization included inflow procedures, such as aortofemoral (n = 25) or extraanatomic bypass (axillofemoral or femorofemoral, n = 11); infrainguinal reconstruction, including femoropopliteal or distal bypass (n = 43), and other procedures to improve perfusion of the limb or correct complications after previous vascular reconstruction upon the extremity (n = 31). Perioperative (30 days) mortality rate was 0.9 per cent and 97.0 per cent of the patients were discharged alive from the hospital. Myocardial infarction (MI) occurred in 3.6 per cent, new ventricular arrhythmia in 1.8 per cent and congestive heart failure in 6.4 per cent of the patients during the perioperative period. During follow-up study (607 +/- 363 days), 7.3 per cent required major amputation, ipsilateral to reconstruction, 5.5 per cent required surgical or angiographic revision for hemodynamic failure of the reconstruction prior to thrombosis and 12.7 per cent thrombosed part or all of the reconstruction. Revascularization failure did not appear to be related to the level of cardiac function. Those with normal (greater than 50 per cent) EF had greater over-all survival by life table analysis than those with EF less than or equal to 50 per cent (p = 0.0006, Mantel-Cox test). Ventricular wall motion abnormalities were associated with reduced over-all survival (p = 0.008, Mantel-Cox test). The presence of angina or previous MI, singularly or in combination, did not have an adverse effect on over-all survival, whereas diabetes (p = 0.0058, Mantel-Cox test) and cigarette smoking (p = 0.0137, Breslow test) were associated with significantly diminished over-all survival. Preoperative RNVG can identify subgroups at a survival disadvantage after revascularization of the extremity in a population in which the presence of angina or previous MI does not predict survival.

Adult↗
PubMed1990

Pleuroperitoneal communication associated with malignant ascites. A potential cause for new pleural effusion suggestive of pulmonary embolism.

A patient with metastatic gastric carcinoma and malignant ascites developed sudden-onset dyspnea secondary to a new large left pleural effusion. A radionuclide lung scan performed for suspected pulmonary embolism was indeterminate. Scintigraphy performed following intraperitoneal administration of Tc-99m sulfur colloid subsequently demonstrated rapid accumulation of activity in the left pleural space, indicating the presence of a pleuroperitoneal communication. In a patient with known or suspected ascites, a new pleural effusion, and an indeterminate lung scan, peritoneal scintigraphy may identify the origin of the effusion and obviate the need for further invasive evaluation for possible pulmonary embolism.

Aged↗
PubMed1989

Assessment of myocardial viability with SPECT and PET imaging.

The use of thrombolytic therapy for the treatment of acute myocardial infarction has increased the number of patients presenting for assessment of myocardial viability. Stress SPECT 201Tl perfusion imaging performed in the conventional manner with delayed imaging at 4 hr can identify a large percentage of patients with ischemic but viable areas of myocardium. In some patients, delayed imaging up to as long as 24-48 hr after exercise may be required to show 201Tl redistribution indicative of viability. Thus, in most patients, stress 201Tl scintigraphy will correctly identify the presence of viable myocardium. PET imaging, with its ability to assess blood flow and metabolism separately, offers the ability to identify myocardial areas with diminished blood flow but preserved metabolism. Areas with such a blood flow-metabolism mismatch may benefit from revascularization, even in the absence of 201Tl redistribution. The exact role PET will play in the initial evaluation of patients presenting for assessment of myocardial viability remains to be established as more clinical data are accumulated.

Heart↗
PubMed1989

Indium-111 leukocyte scintigraphic detection of myocardial abscess formation in patients with endocarditis.

Myocardial abscess formation in patients with bacterial endocarditis in most clinical settings, especially in patients with prosthetic valves, is a primary indicator for surgical valve replacement. We report the detection of myocardial abscesses using 111In leukocyte scintigraphy in three patients with prosthetic or native valve endocarditis and nondiagnostic echocardiograms. Leukocyte scintigraphy may allow identification of myocardial abscess formation earlier than other imaging modalities.

Abscess↗
PubMed1988

The role of preoperative radionuclide left ventricular ejection fraction for risk assessment in carotid surgery.

Radionuclide ejection fraction (EF) and ventricular wall motion were determined in 73 patients before 82 carotid operations (79 carotid endarterectomies [CEAs] and three cervical carotid-subclavian bypasses). The EF was 55% +/- 13%, ranging from 21% to 77%. Thirty-three percent (24/73) had low EF (less than or equal to 50%), and 44% (28/63) had myocardial wall motion abnormalities. Perioperative cardiac complications, including myocardial infarction (MI), new ventricular arrhythmia, or severe congestive heart failure, were present after 12.2% (10/82) of the operations. Perioperative MI was present in 4.9% (4/82); in 50% of these it was fatal. Perioperative (30-day) stroke was present in 2.5% (2/79) of those undergoing CEA. Life table analysis revealed overall survival was lower in patients with EF of 35% or less vs those with EF over 35% during follow-up (522 +/- 280 days). Perioperative cardiac complications were more frequent with EF of 35% or less, occurring in 43% (3/7) vs 9% (7/75) of cases with EF over 35%. There was no statistical difference in perioperative mortality, but cumulative mortality differed, being 57% (4/7) in those with EF of 35% or less vs 11% (7/66) in patients with EF over 35%. Patients with EF of 35% or less are at increased risk for perioperative cardiac complications and reduced overall survival following carotid surgery.

Aged↗
PubMed1988

Perioperative and late outcome in patients with left ventricular ejection fraction of 35% or less who require major vascular surgery.

Survival in patients with diminished left ventricular ejection fraction (EF) is reduced after major vascular surgery. The objective of this study was to determine perioperative (30-day) and subsequent outcome after major vascular surgery in those with severe cardiac dysfunction, defined by EF being 35% or less (normal EF greater than 50%). From Aug. 1, 1984 to Jan. 1, 1988, 35 patients with EF equal to 27.7% +/- 6.1% (mean +/- 1 standard deviation) have required 47 major vascular procedures: 53% (n = 25) were limb revascularizations; 21% (n = 10) were direct aortoiliac aneurysm repairs: 23% (n = 11) were carotid endarterectomies: one patient had transaortic renal endarterectomy. Two deaths occurred within the first 30 days, yielding a 4.3% perioperative mortality rate (2 of 47 procedures). The cumulative mortality rate for the entire group during follow-up of 410 +/- 390 days was 40% (14 of 35 patients). Most late deaths (71%) occurred within the first 6 months after surgery and each was due to cardiovascular complications. Survival for those with an EF of 29% or less was significantly worse than for those with an EF greater than 29%, determined by life-table analysis (p less than 0.012, Mantel-Cox). The cumulative mortality rate was 59% with an EF of 29% or less and 18% in those with an EF greater than 29% (p less than 0.029, two-tailed Fisher exact test). The perioperative mortality rate for those with an EF of 35% or less who require major vascular surgery is acceptable, but overall survival during follow-up is diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1988

The influence of collimators on SPECT center of rotation measurements: artifact generation and acceptance testing.

Misalignment between the electronic and mechanical axes of rotation will result in artifact generation and image degradation during single photon emission computed tomography (SPECT) reconstruction. Acceptance and quality control testing procedures have not emphasized the variability in center of rotation (COR) measurements caused by collimators and the need to verify uniformity across the full collimator field of view (FOV). Variation from the mean COR across the FOV was tested in four different collimators using multiple point source acquisitions. The mean COR was different for each collimator and two of the four had a greater than 0.5 pixel difference from the mean COR on some area of the FOV. This variation makes these collimators unacceptable for SPECT acquisition. Thus, initial acceptance testing of SPECT collimators should verify a uniform COR across the full FOV and collimators with a variability from the mean COR greater than 0.5 pixels should be rejected.

Calibration↗
PubMed1988

The role of preoperative radionuclide ejection fraction in direct abdominal aortic aneurysm repair.

Preoperative radionuclide ventriculography was performed in 60 patients to assess whether such testing could define those at increased risk after direct abdominal aortic aneurysm (AAA) repair. None of the patients had prophylactic coronary artery reconstruction to reduce the risk of AAA repair despite angina in 27% and previous myocardial infarction (MI) in 42%. The mean ejection fraction (EF) was 52% +/- 15% (range 14% to 78%). Low EF (normal greater than 50%) was present in 40%, whereas ventricular wall motion abnormalities were present in 39% of patients. The overall perioperative (30-day) mortality rate was 5%. MI occurred in 7% within 30 postoperative days; none was fatal. Life-table analysis revealed that overall survival after AAA repair was significantly lower in patients with an EF of 50% or less (p less than 0.025, Mantel-Cox) during a follow-up of 20.1 +/- 11.9 months. Overall survival differences were even more striking for those with an EF of 35% or less (p = 0.003, Mantel-Cox). There was a marked difference in the cumulative mortality rate during follow-up, being 50% in those patients with an EF of 35% or less (n = 10) compared with 14% in those with an EF greater than 35% (n = 50, p = 0.036, Fisher exact test). There was no statistical difference in the incidence of perioperative MI or perioperative death for those with an EF of 35% or less vs EF greater than 35%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Evaluation of myocardial perfusion and function by single photon emission computed tomography.

Although planar radionuclide techniques provide accurate, noninvasive measurements of myocardial perfusion and function that are of proven clinical value in the evaluation of the cardiac patient, they are limited by poor object contrast and superimposition of surrounding structures. Due to incomplete angular sampling and significant longitudinal distortion, limited angle tomography did not solve these problems. Single photon emission computed tomography (SPECT) can acquire scintillation information over very small angles of rotation and, thus, improve both object contrast and delineation of overlying or adjacent structures without distortion. The early SPECT systems were cumbersome, dependent on individual user developed software, and had extremely long acquisition and processing time. Improved camera design, new software algorithms, and the use of array processors have simplified and standardized quality control, decreased processing time, and minimized the number of user interventions. New image display formats and quantitative methods of analysis have made interpretation less cumbersome, more reliable and highly reproducible. Cardiac SPECT has been used with thallium-201 and gated blood pool imaging in both research and clinical applications and shown an improvement over planar methods of acquisition.

Algorithms↗
PubMed1986

Indium-111 labeled leukocyte uptake: false-positive results in noninfected pseudoaneurysms.

Indium-111 (In-111) leukocyte scintigraphy was performed in two patients with postsurgical pseudoaneurysms as part of preoperative evaluation for evidence of graft infection. Despite positive In-111 uptake by the pseudoaneurysms, surgical and pathologic examinations failed to reveal any evidence of infection. The most likely explanation for the false-positive results is the labeling of "contaminating" platelets and erythrocytes in the leukocyte mixture. Caution must be exercised in interpretation of In-111 leukocyte scans in patients with postsurgical pseudoaneurysms.

Aneurysm↗
PubMed1985

Hepatic localization of Tc-99m MAA in inferior vena cava obstruction.

Two cases of hepatic localization of Tc-99m MAA following injection through the lower extremity venous system are presented. These cases show two different patterns of hepatic uptake, which are related to the likely routes of ilioportal shunting in inferior vena cava obstruction.

Adult↗