Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 42
Filtrar
2.
Transplant Proc ; 46(9): 3194-8, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25420857

RESUMO

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death in predialysis chronic kidney disease (CKD) and dialysis patients as well as in renal transplant recipients (RTRs). Left ventricular hypertrophy (LVH) starts early during the course of CKD and is a strong predictor of CVD in this population. Regression of LVH after a successful renal transplantation remains a debatable issue among investigators, whereas there is little data comparing echocardiographic measurements between patients with predialysis CKD and RTRs. AIM: The aim of this study was to compare echocardiographic measurements of LV structure and function between predialysis CKD patients and RTRs of similar renal function level. PATIENTS AND METHODS: We conducted a case control study with individual (1:2) matching from the Renal Transplant and the predialysis CKD Outpatient Clinic. For each of the 36 RTRs, two matched for gender, age and estimated glomerular filtration rate (eGFR) predialysis CKD outpatients (72 patients) were included. All patients underwent transthoracic echocardiography and LV mass, LV mass index [LVM and LVMI = LVM/BSA g/m(2)] and indices of systolic function were measured. In a subgroup of 12 RTRs we retrospectively assessed and compared the LVMI measurements at three different time points, during predialysis, dialysis and post transplant period. RESULTS: The prevalence of LVH was 33% in RTRs and 52% in CKD patients (ns). RTRs had significantly lower LVM and LVMI levels compared with predialysis CKD patients (P = .006 and P = .008) while the other echocardiographic indices did not differ. In the subgroup of 12 RTRs, post-transplant LVMI levels (105 ± 25 g/m(2)) were significantly lower in comparison with predialysis (147 ± 57 g/m(2)) and dialysis LVMI levels (169 ± 72 g/m(2)) (P = .01, P = .01, respectively). CONCLUSION: RTRs had significantly lower LVMI compared with predialysis CKD patients of similar age, renal function, hemoglobin and blood pressure level.


Assuntos
Ecocardiografia , Ventrículos do Coração/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/etiologia , Transplante de Rim , Insuficiência Renal Crônica/complicações , Transplantados , Função Ventricular Esquerda/fisiologia , Feminino , Grécia/epidemiologia , Ventrículos do Coração/fisiopatologia , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico por imagem , Hipertrofia Ventricular Esquerda/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Diálise Renal , Insuficiência Renal Crônica/diagnóstico por imagem , Insuficiência Renal Crônica/terapia , Estudos Retrospectivos
3.
Artigo em Inglês | MEDLINE | ID: mdl-23366469

RESUMO

The aim of this study is to describe a new method for three-dimensional (3D) reconstruction of coronary arteries using Frequency Domain Optical Coherence Tomography (FD-OCT) images. The rationale is to fuse the information about the curvature of the artery, derived from biplane angiographies, with the information regarding the lumen wall, which is produced from the FD-OCT examination. The method is based on a three step approach. In the first step the lumen borders in FD-OCT images are detected. In the second step a 3D curve is produced using the center line of the vessel from the two biplane projections. Finally in the third step the detected lumen borders are placed perpendicularly onto the path based on the centroid of each lumen border. The result is a 3D reconstructed artery produced by all the lumen borders of the FD-OCT pullback representing the 3D arterial geometry of the vessel.


Assuntos
Angiografia Coronária/métodos , Vasos Coronários/fisiologia , Tomografia de Coerência Óptica/métodos , Algoritmos , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional
4.
J Cardiovasc Surg (Torino) ; 52(6): 769-78, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22051986

RESUMO

AIM: The management of abdominal aortic aneurysm with endovascular repair (EVAR) requires extended exposure to ionizing radiation, before, during and after the intervention. The aim of this study was to quantify the radiological risks to patients and operating team, and to develop strategies to assess and reduce them. METHODS: EVAR was carried out in 97 patients using either a low-power mobile or a high-power stationary fluoroscopic unit. Empirically determined relationships between the indicated dose area product (DAP) and peak skin dose, obtained by direct in vivo dosimetry in a subgroup of patients, were used to predict the peak skin dose. Individual worker monitoring was used to assess personnel radiological burden. RESULTS: The probability for radiation induced biological effects due to the repair itself and the preoperative and life-long surveillance, as carried out, was about 2.4 10-3. The peak skin dose of repairs was linearly correlated with the DAP and did not exceed 1.2 Gy. The collective effective dose of the staff that carried out repairs using the mobile unit was 5.5 and 8 µSv per repair using an angiographic and a surgical table, respectively. The use of the high-power fluoroscopic unit resulted in a many fold higher radiation burden to both patient and personnel. CONCLUSION: The optimum strategy, including equipment-related factors, procedure-conduct factors and follow-up procedures, has to be studied, justified and optimized in each medical facility.


Assuntos
Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Abdominal/cirurgia , Aortografia/efeitos adversos , Procedimentos Endovasculares , Doenças Profissionais/prevenção & controle , Doses de Radiação , Lesões por Radiação/prevenção & controle , Radiografia Intervencionista/efeitos adversos , Tomografia Computadorizada por Raios X/efeitos adversos , Idoso , Idoso de 80 Anos ou mais , Fluoroscopia/efeitos adversos , Grécia , Humanos , Pessoa de Meia-Idade , Doenças Profissionais/etiologia , Exposição Ocupacional , Valor Preditivo dos Testes , Lesões por Radiação/etiologia , Medição de Risco , Fatores de Risco , Comportamento de Redução do Risco , Dosimetria Termoluminescente , Fatores de Tempo , Resultado do Tratamento
5.
IEEE Trans Biomed Eng ; 58(12): 3464-8, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21846599

RESUMO

In this work, we present a platform for the development of multiscale patient-specific artery and atherogenesis models. The platform, called ARTool, integrates technologies of 3-D image reconstruction from various image modalities, blood flow and biological models of mass transfer, plaque characterization, and plaque growth. Patient images are acquired for the development of the 3-D model of the patient specific arteries. Then, blood flow is modeled within the arterial models for the calculation of the wall shear stress distribution (WSS). WSS is combined with other patient-specific parameters for the development of the plaque progression models. Real-time simulation can be performed for same cases in grid environment. The platform is evaluated using both animal and human data.


Assuntos
Aterosclerose/fisiopatologia , Velocidade do Fluxo Sanguíneo/fisiologia , Processamento de Imagem Assistida por Computador/métodos , Modelos Cardiovasculares , Placa Aterosclerótica/fisiopatologia , Animais , Aterosclerose/patologia , Simulação por Computador , Angiografia Coronária , Humanos , Placa Aterosclerótica/patologia
6.
Artigo em Inglês | MEDLINE | ID: mdl-22255335

RESUMO

Optical Coherence Tomography (OCT) is a fiber--optic imaging modality which produces high resolution tomographic images of the coronary lumen and outer vessel wall. While OCT images present morphological information in highly resolved detail, the characterization of the various plaque components relies on trained readers. The aim of this study is to extract a set of features in grayscale OCT images and to use them in order to classify the atherosclerotic plaque. Intensity and texture based features we used in order to classify the plaque in four plaque types: Calcium (C), Lipid Pool (LP), Fibrous Tissue (FT) and Mixed Plaque (MP). 50 OCT annotated images from 3 patients were used to train and test the proposed plaque characterization method. Using a Random Forests classifier overall classification accuracy 80.41% is reported.


Assuntos
Aterosclerose/patologia , Tomografia de Coerência Óptica , Humanos , Modelos Teóricos
7.
Int Angiol ; 29(3): 273-7, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20502416

RESUMO

Four patients suffering from concomitant descending thoracic pathology and abdominal aortic aneurysms were treated with endovascular stent-grafts simultaneously. Graft deployment was successful and uneventful in all patients. Paraplegia was not observed. One patient developed an abdominal type Ib endoleak at 12 months which was repaired endovascularly. One patient died from multiorgan failure 3 days after the deployment of the grafts. After 18, 36 and 42 months follow up all the other patients are well without any graft related complication. Simultaneous endovascular repair for coexisting descending thoracic and abdominal aortic pathologies might be an acceptable alternative to open surgery or hybrid operations, at least for the high risk patients.


Assuntos
Aneurisma da Aorta Abdominal/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Dissecção Aórtica/cirurgia , Implante de Prótese Vascular , Idoso , Idoso de 80 Anos ou mais , Dissecção Aórtica/complicações , Dissecção Aórtica/diagnóstico por imagem , Aneurisma da Aorta Abdominal/complicações , Aneurisma da Aorta Abdominal/diagnóstico por imagem , Aneurisma da Aorta Torácica/complicações , Aneurisma da Aorta Torácica/diagnóstico por imagem , Aortografia/métodos , Prótese Vascular , Implante de Prótese Vascular/efeitos adversos , Implante de Prótese Vascular/instrumentação , Implante de Prótese Vascular/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência de Múltiplos Órgãos/etiologia , Insuficiência de Múltiplos Órgãos/mortalidade , Falha de Prótese , Stents , Fatores de Tempo , Tomografia Computadorizada por Raios X , Resultado do Tratamento
8.
Cardiovasc Intervent Radiol ; 31(1): 149-57, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-17943350

RESUMO

PURPOSE: To investigate the influence that measurement of balloon volume as a controlled variable in addition to balloon pressure has on the outcome of balloon angioplasty in an experimental model. METHODS: One hundred and three segments of explanted normal porcine carotid arteries were obtained. Five were used as controls, and the remaining 98 were subjected to balloon angioplasty with simultaneous measurement of balloon volume and pressure. These arteries were randomized into two groups. In one group the endpoint of the angioplasty was determined by balloon pressure (pressure-limited group, PLG) and in the other group by balloon volume (volume-limited group, VLG). Pressure/volume curves for each procedure were constructed by continuous measurement of both parameters by a purpose-designed computer-controlled inflation device. The diameter of each arterial segment was measured by intravascular ultrasound (IVUS) and the ratio of the inflated balloon to arterial diameter calculated. Arterial appearances after angioplasty were recorded using IVUS. RESULTS: The balloon volumes measured at the endpoint of angioplasty were significantly smaller in the PLG compared with the VLG (p < 0.001). Three types of pressure/volume curves were identified: A, B, and C. In the type A curves, IVUS identified fissures in 28% (17/60) and the examination was normal in 72% (43/60). In the type B curves, IVUS identified fissures in 44% (4/9), dissections in 22% (2/9), and the examination was normal in 33% (3/9). In the type C curves, IVUS identified fissures in 44% (4/9) and dissection in 56% (5/9) with no normal examinations. In undamaged arterial segments a very high correlation was achieved between balloon volume and the balloon/artery ratio (Pearson correlation = -0.979, R(2) = 0.957, p < 0.0001, n = 27). CONCLUSION: The measurement of pressure and volume during angioplasty enabled the construction of pressure/volume curves that showed deviations from the curves obtained in air. The balloon volume results, and significant deviation of the curve shape from the control curve shape, predicted vessel damage, which was confirmed by the IVUS appearance of the vessel after angioplasty. When pressure was used as the endpoint of balloon inflation the balloons were significantly underdilated compared with the manufacturer's nominal sizes. These data indicate that monitoring of pressure and volume during angioplasty may provide an alternative method of predicting vessel damage.


Assuntos
Angioplastia com Balão/métodos , Artérias Carótidas/fisiologia , Lesões das Artérias Carótidas/prevenção & controle , Angioplastia com Balão/efeitos adversos , Animais , Artérias Carótidas/diagnóstico por imagem , Lesões das Artérias Carótidas/etiologia , Modelos Animais de Doenças , Pressão , Suínos , Ultrassonografia de Intervenção
9.
IEEE Trans Biomed Eng ; 54(9): 1710-4, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17867365

RESUMO

In this paper, we use a one-dimensional model of the rabbit sinoatrial node (SAN), and we investigate the response of the model to hyperpolarizing and depolarizing stimulus. Depending on the stimulus timing, either a delay or an advance in the occurrence of next action potential is produced. This resetting behavior of the model is quantified in terms of phase transition curves (PTCs) for short electrical current pulses of varying amplitude which span the whole period. The main focus of this paper is to compare the dynamic properties of the spatially extended system and the single cell model. The detailed analysis of the results provides new insights in the understanding of the transition from the theoretical single cell models to the spatially extended systems.


Assuntos
Relógios Biológicos/fisiologia , Estimulação Cardíaca Artificial/métodos , Modelos Cardiovasculares , Oscilometria/métodos , Nó Sinoatrial/fisiologia , Animais , Simulação por Computador , Coelhos
10.
Comput Biol Med ; 37(1): 8-20, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16297376

RESUMO

In this work, the dynamic response of the sinoatrial node (SAN), the natural pacemaker of the heart, to short external stimuli is investigated using the Zhang et al. model. The model equations are solved twice for the central cell and for the peripheral cell. A short current pulse is applied to reset the spontaneous rhythmic activity of the single sinoatrial node cell. Depending on the stimulus timing either a delay or an advance in the occurrence of next action potential is produced. This resetting behavior is quantified in terms of phase transition curves (PTCs) for short electrical current pulses of varying amplitude which span the whole period. For low stimulus amplitudes the transition from advance to delay is smooth, while at higher amplitudes abrupt changes and discontinuities are observed in PTCs. Such discontinuities reveal critical stimuli, the application of which can result in annihilation of activity in central SAN cells. The detailed analysis of the ionic mechanisms involved in its resetting behavior of sinoatrial node cell models provides new insight into the dynamics and physiology of excitation of the sinoatrial node of the heart.


Assuntos
Modelos Cardiovasculares , Nó Sinoatrial/fisiologia , Potenciais de Ação , Animais , Simulação por Computador , Estimulação Elétrica , Eletrofisiologia , Humanos , Técnicas In Vitro , Potenciais da Membrana , Modelos Estatísticos , Nó Sinoatrial/citologia
11.
J Biomech ; 38(7): 1423-31, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15922753

RESUMO

Fourier analysis is usually employed for the computation of blood flow in arteries. Although the orthogonality of Fourier eigenfunctions guarantees the accurate mathematical modeling of the blood pressure and flow waveforms, the physics behind this objective function is frequently missing. We propose a new method to account for the blood pressure and flow, single-cycle (systole-diastole) waveforms. It is based on the one dimensional hydrodynamic mass and momentum conservation equations for viscous flow. The similarity of the linear problem, under discussion, with related transmission line theory in electromagnetic wave propagation, permits expansion in anharmonic, non-separable eigenfunctions. In some cases one term in the expansion is adequate to fit the main peak of the observed waveforms. Analytical formulas are derived for the dependence of the pressure and flow main peaks on whole blood viscosity and distance from the heart, which interpret observations related to hypertension.


Assuntos
Artérias/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Modelos Cardiovasculares , Fluxo Pulsátil/fisiologia , Animais , Fenômenos Fisiológicos Sanguíneos , Viscosidade Sanguínea/fisiologia , Simulação por Computador , Humanos , Oscilometria/métodos
12.
Br J Radiol ; 78(926): 122-9, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15681323

RESUMO

The aim of this work was to evaluate a new semi-automated intravascular ultrasound (IVUS) border detection method. The method was used to identify the lumen and the external elastic membrane or the borders of stents in 80 IVUS images, randomly selected from 10 consecutive human coronary arteries. These semi-automated results were compared with observations of two experts. Several indices in each case were obtained in order fully to evaluate the method. The time required for identification of the borders was also recorded. The interobserver variability of the method ranged from 1.21% to 5.61%, the correlation coefficient from 0.98 to 0.99, the slope was close to unity (0.94-1.03), the y intercept close to zero and the Williams index value was close to unity (range 0.67-0.91). The time (mean+/-SD) required for the method to identify the borders of the different vessel layers for the whole IVUS sequence was 5.2+/-0.2 min. The results demonstrate that the method is reliable and capable of identifying rapidly and accurately the different vessel layers depicted in IVUS images.


Assuntos
Doença das Coronárias/diagnóstico por imagem , Vasos Coronários/diagnóstico por imagem , Endossonografia/métodos , Stents , Idoso , Automação , Doença das Coronárias/patologia , Vasos Coronários/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Sensibilidade e Especificidade
13.
Cardiovasc Intervent Radiol ; 27(3): 268-70, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15359470

RESUMO

Three cases of local thrombolysis in the treatment of acute lower limb ischemia complicating the utilization of the Duett sealing device are presented. Routine usage of several vascular closure devices after cardiac catheterization and percutaneous coronary intervention (PCI) has been adopted in our institution during the last 3 years (September 1999 to April 2003). The Duett closure device has been used in 420 patients (post-coronary angiography, 359; post-PCI, 61). Three patients (0.7%) demonstrated acute leg ischemia used by inadvertent intravascular administration of the sealing material related to this device. All three were treated successfully by catheter-directed local thromolysis (tissue plasminogen activator 5 mg bolus followed initially by 1 mg/hr and consequently by 0.5-1.0 mg/hr depending upon the development of significant hematoma and lasting for 24 hr). In conclusion, interventional treatment using local thrombolysis should be the first-line treatment in acute lower limb ischemia complicating the utilization of the Duett sealing device.


Assuntos
Cateterismo Cardíaco/instrumentação , Técnicas Hemostáticas/instrumentação , Isquemia/tratamento farmacológico , Isquemia/etiologia , Perna (Membro)/irrigação sanguínea , Terapia Trombolítica/métodos , Doença Aguda , Adulto , Idoso , Angiografia Digital , Angioplastia Coronária com Balão/efeitos adversos , Angioplastia Coronária com Balão/métodos , Anticoagulantes/uso terapêutico , Cateterismo Cardíaco/efeitos adversos , Feminino , Artéria Femoral , Seguimentos , Técnicas Hemostáticas/efeitos adversos , Humanos , Isquemia/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Artéria Poplítea , Estudos Retrospectivos , Medição de Risco , Resultado do Tratamento
14.
Angiology ; 55(2): 187-94, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15026874

RESUMO

Acute coronary syndromes (ACS) represent the most common cause of morbidity and mortality in the Western world. Relative epidemiologic data for Greece, a Mediterranean country, are sparse. The aim of the study was to determine the incidence and the clinical presentations of ACS. Over a 1-year period we conducted a prospective, population-based survey of ACS cases in an isolated area of northwestern (NW) Greece with 170,000 inhabitants. Every patient living in the study area, aged <80 years, without history of coronary artery disease, who presented with symptoms suspicious for ACS and was hospitalized for at least 24 hours was eligible for inclusion in the study. For sudden cardiac deaths, relative information was obtained from the autopsy report or the physician who documented death. Additional information regarding timing and associated conditions was obtained from relatives. The diagnosis and classification of the studied cases was performed according to World Health Organization and European Society of Cardiology criteria. The authors identified 352 patients (265 men, 87 women, mean age 62.5 +/-10 and 68 +/-9.5 years, respectively) with first-appeared ACS (174 non-ST elevation, 105 ST elevation, 73 sudden cardiac deaths). Fifty-six patients with other forms of ischemic heart disease (stable angina, heart failure, and silent ischemia) were not included in the analysis. Moreover, 154 patients with chest pain and normal appearing EGG at rest, normal values for enzymes (CK, troponin), and negative exercise testing, as well as 77 patients with normal findings from coronary angiography studies, were also excluded. The annual incidence for the age group of 30-79 was 39/10,000 inhabitants (60.6 for men and 19 for women). The incidence of ACS increased with age in both sexes and was higher in men even after the age of 70. About one third of the ACS and half of the sudden cardiac deaths occurred in the age group of 70-79. Only 3 patients were successfully resuscitated. ACS are common in this area of NW Greece and the majority of them present in a form amenable to therapeutic manipulations. Twenty percent of patients died suddenly, and a very small percentage of these were successfully resuscitated. Preventive measures and acute management facilities need to be improved, even in a Mediterranean country where the incidence of ischemic heart disease is relatively lower than in northern European countries.


Assuntos
Angina Instável/epidemiologia , Morte Súbita Cardíaca/epidemiologia , Infarto do Miocárdio/epidemiologia , Vigilância da População , Doença Aguda , Adulto , Idoso , Angina Instável/fisiopatologia , Feminino , Grécia/epidemiologia , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/fisiopatologia , Estudos Prospectivos , Síndrome
15.
Heart ; 89(3): 306-10, 2003 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-12591837

RESUMO

OBJECTIVE: To examine the effects of baseline left ventricular function on the haemodynamic and catecholamine responses to ventricular tachycardia. DESIGN: Experimental cohort study. SETTING: Cardiac catheterisation laboratory in tertiary referral centre. SUBJECTS: 24 patients (19 male, 5 female; mean (SD) age, 59 (10) years) without coronary artery disease, divided into two groups with normal or impaired left ventricular function: group A, ejection fraction > 65% (n = 10); group B, ejection fraction < 45% (n = 14). Other medical and demographic factors were similar in the two groups. INTERVENTIONS: Ventricular tachycardia was simulated with rapid pacing at 150 beats/min for 10 minutes. MAIN OUTCOME MEASURES: Arterial blood pressure; venous plasma catecholamine concentrations. RESULTS: During rapid pacing, blood pressure was lower in group B (with impaired left ventricular function) than in group A: systolic blood pressure, 102 (11) v 115 (9) mm Hg (p = 0.005); mean blood pressure, 79 (6) v 85 (6) mm Hg (p = 0.02). The ejection fraction correlated with the lowest systolic blood pressure (r = 0.64, p = 0.0006). Although the rise in adrenaline was comparable between the two groups, the rise in noradrenaline was more pronounced (p < 0.05) in patients in group B. CONCLUSION: At low rates and in selected patients, the underlying state of left ventricular function affects haemodynamic tolerance of ventricular tachycardia. Patients with impaired left ventricular function have a lower blood pressure during ventricular tachycardia, despite an exaggerated noradrenaline release.


Assuntos
Pressão Sanguínea/fisiologia , Catecolaminas/sangue , Volume Sistólico/fisiologia , Taquicardia Ventricular/fisiopatologia , Disfunção Ventricular Esquerda/fisiopatologia , Função Ventricular Esquerda/fisiologia , Estimulação Cardíaca Artificial , Estudos de Coortes , Epinefrina/sangue , Feminino , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/sangue , Taquicardia Ventricular/sangue
16.
Cardiovasc Radiat Med ; 3(1): 20-5, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12479912

RESUMO

PURPOSE: To study the dose and time effect of external beam irradiation on the morphometry of both angioplasted and nonangioplasted arteries in a hypercholesterolemic rabbit model. METHODS AND MATERIALS: Eight groups of rabbit femoral arteries were studied: arteries (a) with no intervention, (b) irradiated with a 12-Gy 6 MV X-ray dose, (c) with a 18-Gy, (d) treated with balloon angioplasty, (e) dosed with 12-Gy half an hour post-angioplasty, (f) dosed with 18-Gy half an hour post-angioplasty, (g) dosed with 12-Gy 48 h post angioplasty, (g) dosed with 18-Gy 48 h post angioplasty. RESULTS: External irradiation at either 12 or 18 Gy was not found to change vessel morphometry in noninjured arteries. The 12-Gy dose given soon after angioplasty further increased percentage stenosis (63% on the average), despite the preservation of the lumen cross-sectional area. Positive remodeling was not observed in arteries given 18-Gy half an hour post angioplasty to counterbalance the increased neointimal formation. Therefore, this treatment resulted in a drastic reduction in lumen area and in enhancement of percentage stenosis (84% on the average). On the contrary, the delayed irradiation of the angioplasted arteries at either 12 or 18 Gy was not found to influence any of the studied morphometric parameters 5 weeks after angioplasty. CONCLUSIONS: Uniform external beam irradiation up to 18 Gy was well tolerated by intact femoral arteries. Prompt 12- or 18-Gy irradiations accentuated percentage stenosis. However the lumen cross-sectional area was preserved only at the lower dose point. Delayed irradiation at any dose did not influence the restenosis process.


Assuntos
Angioplastia com Balão , Artéria Femoral/efeitos da radiação , Artéria Femoral/cirurgia , Hipercolesterolemia/terapia , Terapia por Raios X , Animais , Arteriopatias Oclusivas/etiologia , Modelos Animais de Doenças , Relação Dose-Resposta à Radiação , Hipercolesterolemia/complicações , Masculino , Complicações Pós-Operatórias/etiologia , Coelhos , Dosagem Radioterapêutica , Fatores de Tempo , Resultado do Tratamento , Túnica Íntima/efeitos da radiação , Túnica Íntima/cirurgia , Túnica Média/efeitos da radiação , Túnica Média/cirurgia
18.
Curr Med Res Opin ; 18(2): 108-12, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12017208

RESUMO

It is known that myocardial ischaemia increases platelet aggregatory response to various agonists, ex vivo. We investigated the platelet aggregatory response to platelet activating factor (PAF), ex vivo, in patients with non-ST elevation acute coronary syndromes and determined the specificity and sensitivity of this response. Thirty-two consecutive patients with non-ST elevation acute coronary syndromes and 20 healthy volunteers were studied. Platelet aggregation in platelet-rich plasma was studied on the day of admission. The maximal aggregation achieved within 2 min after the addition of PAF (100 nM) was expressed as a percentage of 100% light transmission. PAF EC50 values were defined as the concentration that induces 50% of maximal aggregation. The PAF EC50 values of the non-ST elevation acute coronary syndromes patients were significantly lower compared to those of the controls (p < 0.0001). The maximal percentage of aggregation was also significantly higher (p < 0.0005). Ninety-one per cent of the patients were correctly classified using PAF EC50 values (specificity 90.0% and sensitivity 91.2%); the corresponding results using the maximal percentage of aggregation were 80% (specificity 70.0% and sensitivity 87.5%). The estimated values used as thresholds were 22.47 nM and 17.97 for the PAF EC50 and the maximal percentage of aggregation, respectively. The results of the present study suggest that platelet hyperaggregability to PAF, ex vivo, in non-ST elevation acute coronary syndromes is characterised by a high specificity and sensitivity, and thus it may represent a mechanism contributing to the pathophysiology of acute coronary syndromes.


Assuntos
Doença das Coronárias/sangue , Eletrocardiografia , Fator de Ativação de Plaquetas/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Feminino , Humanos , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Síndrome
19.
J Biomech ; 35(6): 813-21, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12021001

RESUMO

Among the proposed techniques for delivering drugs to specific locations within the human body, magnetic drug targeting surpasses due to its non-invasive character and its high targeting efficiency. Although the method has been proposed almost 30 years ago, the technical problems obstruct possible applications. It is the aim of the present work to classify the emerging problems and propose satisfactory answers. A general phenomenological theory is developed and a model case is studied, which incorporates all the physical parameters of the problem.


Assuntos
Sistemas de Liberação de Medicamentos , Hemorreologia/métodos , Magnetismo , Modelos Cardiovasculares , Materiais Biocompatíveis , Velocidade do Fluxo Sanguíneo , Artérias Carótidas/fisiologia , Simulação por Computador , Portadores de Fármacos , Artéria Femoral/fisiologia , Microesferas , Sensibilidade e Especificidade , Aderências Teciduais
20.
J Cardiovasc Risk ; 8(5): 311-7, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11702038

RESUMO

OBJECTIVE: The aim of this study was to investigate the possible associations between lipoprotein(a) [Lp(a)] concentrations or apolipoprotein(a) isoforms and the mode of clinical presentation of coronary heart disease (CHD) (acute thrombotic event or not). METHODS: A total of 131 CHD patients and 71 age- and gender-matched individuals without known CAD (free of symptoms of heart disease) were enrolled in the study. CHD patients were classified into patients with a history of an acute coronary syndrome (ACS, n=94) and patients with stable angina (SA, n=37). Lp(a) levels were measured with an ELISA method, whereas apolipoprotein(a) isoform analysis was performed (in all patients and 33 controls) by electrophoresis in 1.5% SDS-agarose gels followed by immunoblotting. Isoform size was expressed as the number of kringle 4 (K4) repeats. RESULTS: ACS patients had higher Lp(a) plasma levels 121.9 (0.8-84.1) mg/dl] and a greater proportion of elevated (> or = 30 mg/dl) Lp(a) concentrations (25.5%) compared with SA patients [9.2 (0.8-50.5) mg/dl, P < 0.01 and 10.8%, P < 0.05] and controls [8.0 (0.8-55.0) mg/dl, P < 0.01 and 11.2%, P < 0.05], while there were no differences between SA patients and controls. The median apolipoprotein(a)-isoform size was 26 K4. In 17 (10%) patients we could not detect any apolipoprotein(a) isoform bands by immunoblotting. ACS patients had a higher proportion of isoforms < 26 K4 (low molecular weight) than SA patients (56/85 vs. 12/33, P < 0.005) and controls (10/29, P < 0.005). CONCLUSIONS: CAD patients with a history of ACS have higher Lp(a) plasma levels and a significantly higher proportion of low molecular weight apolipoprotein(a) isoforms compared with patients with SA or to controls.


Assuntos
Apolipoproteínas/sangue , Doença das Coronárias/sangue , Lipoproteína(a)/sangue , Doença Aguda , Idoso , Apoproteína(a) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Isoformas de Proteínas/sangue , Índice de Gravidade de Doença , Síndrome
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA