RESUMO
Aortic stenosis is increasing in incidence and is now commonly managed with transcatheter aortic valve replacement (TAVR) in intermediate and high-risk patients. Radiologists are likely to encounter patients undergoing this procedure both pre- and postoperatively, and therefore, an understanding of procedural complications is essential. Complications may relate to the access site or approach, or the valve itself. This article will review the most common complications described in literature and focuses on the role of multidetector computed tomography (CT) in their evaluation either exclusively, or complementary to other imaging methods.
Assuntos
Estenose da Valva Aórtica/cirurgia , Tomografia Computadorizada Multidetectores , Complicações Pós-Operatórias/diagnóstico por imagem , Substituição da Valva Aórtica Transcateter , HumanosRESUMO
We report the case of a man found unconscious three weeks following atrial fibrillation (AF) ablation. Cranial and thoracic imaging demonstrated multiple areas of pneumo-embolic infarction secondary to an atrio-oesophageal fistula (AEF). AEF is a recognised, but rare, complication of AF ablation.(1-8) Early recognition is critical as the mortality is 100% without surgical intervention. We consider the postulated mechanisms of AEF formation, the spectrum of clinical presentation, investigations and treatment.
Assuntos
Fibrilação Atrial/cirurgia , Embolia Aérea , Esôfago , Fístula , Hemorragias Intracranianas , Complicações Pós-Operatórias/diagnóstico por imagem , Fibrilação Atrial/diagnóstico por imagem , Embolia Aérea/diagnóstico por imagem , Embolia Aérea/etiologia , Evolução Fatal , Fístula/diagnóstico por imagem , Fístula/etiologia , Humanos , Hemorragias Intracranianas/diagnóstico por imagem , Hemorragias Intracranianas/etiologia , Masculino , Pessoa de Meia-Idade , RadiografiaRESUMO
BACKGROUND: For late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) assessment of atrial scar to guide management and targeting of ablation in atrial fibrillation (AF), an objective, reproducible method of identifying atrial scar is required. OBJECTIVE: To describe an automated method for operator-independent quantification of LGE that correlates with colocated endocardial voltage and clinical outcomes. METHODS: LGE CMR imaging was performed at 2 centers, before and 3 months after pulmonary vein isolation for paroxysmal AF (n = 50). A left atrial (LA) surface scar map was constructed by using automated software, expressing intensity as multiples of standard deviation (SD) above blood pool mean. Twenty-one patients underwent endocardial voltage mapping at the time of pulmonary vein isolation (11 were redo procedures). Scar maps and voltage maps were spatially registered to the same magnetic resonance angiography (MRA) segmentation. RESULTS: The LGE levels of 3, 4, and 5SDs above blood pool mean were associated with progressively lower bipolar voltages compared to the preceding enhancement level (0.85 ± 0.33, 0.50 ± 0.22, and 0.38 ± 0.28 mV; P = .002, P < .001, and P = .048, respectively). The proportion of atrial surface area classified as scar (ie, >3 SD above blood pool mean) on preablation scans was greater in patients with postablation AF recurrence than those without recurrence (6.6% ± 6.7% vs 3.5% ± 3.0%, P = .032). The LA volume >102 mL was associated with a significantly greater proportion of LA scar (6.4% ± 5.9% vs 3.4% ± 2.2%; P = .007). CONCLUSIONS: LA scar quantified automatically by a simple objective method correlates with colocated endocardial voltage. Greater preablation scar is associated with LA dilatation and AF recurrence.
Assuntos
Fibrilação Atrial/patologia , Ablação por Cateter/métodos , Cicatriz/diagnóstico , Meios de Contraste , Gadolínio , Átrios do Coração/patologia , Imageamento por Ressonância Magnética/métodos , Meglumina/análogos & derivados , Compostos Organometálicos , Adulto , Idoso , Fibrilação Atrial/cirurgia , Feminino , Átrios do Coração/cirurgia , Humanos , Aumento da Imagem , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
PURPOSE: This study evaluated the ability of (18)F-FDG PET/CT imaging to predict early response to (90)Y-radioembolization in comparison with contrast-enhanced CT (CECT) using RECIST and lesion density (Choi) criteria. Progression-free survival (PFS) in patients with liver metastases at 2 years and decline in tumour markers were the primary end-points of the study. METHODS: A total of 121 liver lesions were evaluated in 25 patients (14 men, 11 women) with liver-dominant metastatic colorectal cancer who underwent (18)F-FDG PET/CT and CECT before and 6-8 weeks after treatment. Changes in SUV(max), tumour density measured in terms of Hounsfield units and the sum of the longest diameters (LD) were calculated for the target liver lesions in each patient. The patient responses to treatment were categorized using EORTC PET criteria, tumour density criteria (Hounsfield units) and RECIST, and were correlated with the responses of tumour markers and 2-year PFS using Kaplan-Meier plots and the log-rank test for comparison. Multivariate proportional hazards (Cox) regression analysis was performed to assess the effect of relevant prognostic factors on PFS. RESULTS: Using (18)F-FDG PET/CT response criteria, 15 patients had a partial response (PR) and 10 patients had stable disease (SD), while using RECIST only 2 patients had a PR and 23 had SD. Two patients had a PR, 21 SD and 2 progressive disease using tumour density criteria. The mean changes in SUV(max), sum of the LDs and tumour density after treatment were 2.9 ± 2.6, 7.3 ± 14.4 mm and 1.9 ± 13.18 HU, respectively. Patients who had a PR on (18)F-FDG PET/CT had a mean decrease of 44.5 % in SUV(max) compared to those with SD who had a decrease of only 10.3 %. The decreases in SUV(max) and sum of the LDs were significant (p < 0.0001, p < 0.05, respectively) while the decrease in tumour density was not (p > 0.1065). The responses on the (18)F-FDG PET/CT studies were highly correlated with the responses of tumour markers (p < 0.0001 for LDH, p = 0.01 for CEA and p = 0.02 for Ca19-9), while the responses on the CECT studies using both RECIST and tumour density criteria were not significantly correlated with the responses of tumour markers. The responses on (18)F-FDG PET/CT studies also significantly predicted PFS (the median PFS in those with a PR was 12.0 months and in those with SD was 5 months, p < 0.0001), while RECIST and tumour density did not significantly predict PFS. Multivariate analysis demonstrated that responses on (18)F-FDG PET/CT studies and decreases in SUV(max) of ≤ 2.0 were the strongest predictors of PFS. CONCLUSION: Early response assessment to (90)Y-radioembolization using (18)F-FDG PET/CT is superior to RECIST and tumour density, demonstrating a correlation with tumour markers and significantly predicting PFS in patients with liver metastases. This could enable early response-adapted treatment strategies to be employed.
Assuntos
Neoplasias Colorretais/diagnóstico por imagem , Neoplasias Colorretais/radioterapia , Meios de Contraste , Embolização Terapêutica , Fluordesoxiglucose F18 , Imagem Multimodal/métodos , Tomografia por Emissão de Pósitrons , Tomografia Computadorizada por Raios X , Adulto , Idoso , Biomarcadores Tumorais/sangue , Neoplasias Colorretais/sangue , Neoplasias Colorretais/patologia , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento , Carga Tumoral , Radioisótopos de Ítrio/uso terapêuticoRESUMO
OBJECTIVE: Accurate pre-operative evaluation of renal vascular anatomy is essential for successful renal harvest in live donor transplantation. Non-contrast renal MR angiographic (MRA) techniques are potentially well suited to the screening of donors; however, their restricted imaging field of view (FOV) has previously been an important limitation. We sought to assess whether the addition of a large FOV balanced fast field echo (BFFE) steady-state free precession (SSFP) sequence to non-contrast SSFP MRA could overcome this problem. Comparison with contrast-enhanced MRA (CE MRA) and findings at surgery were performed. METHODS: 22 potential renal donors each underwent SSFP and CE MRA. 11 out of 22 potential donors subsequently underwent a donor nephrectomy. RESULTS: All images were diagnostic. Both SSFP MRA and CE MRA identified an equal number of arteries. Surgery confirmed two accessory renal arteries, both demonstrated with both imaging techniques. A third accessory vessel was identified with both techniques on a kidney contralateral to the donated organ. 6 out of 11 procured kidneys demonstrated early branch arteries at surgery, 5 out of 6 of which had been depicted on both SSFP and CE MRA. The median grading of image quality for main renal arteries was slightly better for CE MRA (p=0.048), but for accessory vessels it was better for SSFP MRA. CONCLUSION: This pilot study indicates that by combining free-breathing SSFP MRA with large-FOV bFFE images, an accurate depiction of renal vascular anatomy without the need for intravenous contrast administration can be obtained, as compared with surgical findings and CE MRA.
Assuntos
Transplante de Rim/métodos , Rim/irrigação sanguínea , Doadores Vivos , Angiografia por Ressonância Magnética/métodos , Artéria Renal/anormalidades , Adulto , Circulação Colateral/fisiologia , Meios de Contraste , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nefrectomia , Projetos Piloto , Cuidados Pré-Operatórios/métodos , Estudos Prospectivos , RespiraçãoRESUMO
Functional CT can demonstrate acute quantitative increases in perfusion, permeability and fractional vascular volume in the prostate gland of patients with prostate cancer following radiotherapy (RT). We hypothesize that these quantitative changes can also be demonstrated visually by presenting them as colour parametric maps using custom software. 21 patients with prostate cancer were studied before, and 1-2 weeks after, RT. Repeated CT scans through a single section of the prostate was performed following contrast injection. Capillary permeability, fractional vascular volume and tissue perfusion were calculated and converted to colour maps using a customized Matlab imaging programme. Five "expert" and five "novice" radiologists scored pairs of randomized prostate images as an "increase", "decrease" or "no change" in intensity following RT. Kappa (kappa) statistics was used to assess the concordance of opinions. Significant quantitative increases in all indices occurred after RT, and almost all of the parametric images were scored as an increase in intensity following RT (perfusion = 95%, permeability = 88%, volume = 84%). There was substantial agreement between the experts and novices (kappa: perfusion = 0.93, permeability = 0.80, volume = 0.90), as well as within the expert (kappa: perfusion = 1, permeability = 0.86, volume = 1) and novice (kappa: perfusion = 0.82, permeability = 0.78, volume = 0.78) groups. Functional colour maps of the prostate can reliably portray the hyperaemic response following RT in a group with quantitative increases in perfusion, permeability and fractional vascular volume, and provides a potentially accessible and convenient method for image analysis by radiologists of varying experience.
Assuntos
Competência Clínica/normas , Próstata/efeitos da radiação , Neoplasias da Próstata/radioterapia , Radiologia/normas , Idoso , Idoso de 80 Anos ou mais , Humanos , Masculino , Variações Dependentes do Observador , Próstata/diagnóstico por imagem , Neoplasias da Próstata/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
BACKGROUND: Previous clinical studies have observed relationships between increased intima-media thickness (IMT) in the carotid artery, elevated blood pressure, and low wall shear stress (WSS) calculated from the Poiseuille equation. This study used numerical methods to more accurately determine WSS in the carotid artery and to investigate possible determinants of increased IMT. METHODS: IMT [common carotid artery (CCA) and bulb], CCA flow velocity, brachial systolic (SBP) and diastolic blood pressure (DBP), and carotid systolic pressure (cSBP) were measured in 14 healthy subjects (aged 44 +/- 16 yr). Flow patterns in the carotid bifurcation were determined by computational fluid dynamics (CFD) based on three-dimensional ultrasound geometry. Instantaneous and time-averaged wall shear stress (WSS(av)), oscillatory shear index (OSI), and wall shear stress angle gradients (WSSAG) were calculated. RESULTS: IMT was positively related to SBP, DBP, cSBP, and WSSAG and inversely related to WSS(av) in the CCA. In the bulb, IMT was positively related to SBP and cSBP but was not significantly related to WSS(av) or WSSAG. IMT was unrelated to OSI in both the CCA and the bulb. CONCLUSION: Increased carotid artery IMT in healthy subjects with no evidence of focal plaques is primarily a response to elevated pressure.
Assuntos
Pressão Sanguínea , Artéria Carótida Primitiva/fisiologia , Modelos Cardiovasculares , Fluxo Pulsátil , Túnica Íntima , Túnica Média , Adulto , Idoso , Artéria Braquial/fisiologia , Artéria Carótida Primitiva/diagnóstico por imagem , Feminino , Hemorreologia , Humanos , Interpretação de Imagem Assistida por Computador , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Valores de Referência , Fluxo Sanguíneo Regional , Estresse Mecânico , Fatores de Tempo , Túnica Íntima/diagnóstico por imagem , Túnica Média/diagnóstico por imagem , UltrassonografiaRESUMO
Studies in adults have shown marked changes in geometry and relative positions of the carotid arteries when rotating the head. The aim of this study was to quantify the change in geometry and analyze its effect on carotid hemodynamics as a result of head rotation. The right carotid arteries of nine young adult subjects were investigated in supine position with straight and left turned head positions, respectively. The three-dimensional (3D) carotid geometry was reconstructed by using 3D ultrasound (3D US), and the carotid hemodynamics were calculated by combining 3D US with computational fluid dynamics. It was observed that cross-sectional areas and shapes did not change markedly with head rotation, but carotid vessel center lines altered with planarification of the common carotid artery as a main feature (P < 0.05). Measured common carotid flow rates changed significantly at the individual level when the head was turned, but on the average, the change in mean common carotid flow rate was relatively small (0.37 +/- 1.11 ml/s). The effect of the altered center lines and flow rates on the atherogenic nature of the carotid bifurcation was evaluated by using calculated hemodynamic wall parameters, such as wall shear stress (WSS) and oscillatory shear index (OSI). It was found that WSS and OSI patterns changed significantly with head rotation, but the variations were very subject dependent and could not have been predicted without assessing the altered geometry and flow of the carotid bifurcation for individual cases. This study suggests that there is a need for standardization of the choice of head position in the 3D US scan protocol, and that carotid stents and emboli diverters should be studied in different head positions.
Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Carótidas/diagnóstico por imagem , Artérias Carótidas/fisiologia , Cabeça/irrigação sanguínea , Postura/fisiologia , Adulto , Circulação Cerebrovascular/fisiologia , Feminino , Humanos , Imageamento Tridimensional , Masculino , Estresse Mecânico , UltrassonografiaRESUMO
Atherosclerosis is a major cause of morbidity and mortality. Its apparent link with wall shear stress (WSS) has led to considerable interest in the in vivo estimation of WSS. Determining WSS by combining medical images with computational fluid dynamics (CFD) simulations can be performed both with magnetic resonance imaging (MRI) and three-dimensional ultrasound (3DUS). This study compares predicted 3D flow patterns based on black blood MRI and 3DUS. Velocity fields in the carotid arteries of nine subjects have been reconstructed, and the haemodynamic wall parameters WSS, oscillatory shear index (OSI), WSS gradients (WSSG) and angle gradients (WSSAG) were compared between the two imaging techniques. There was a good qualitative agreement between results derived from MRI and 3DUS (average correlation strength above 0.60). The root mean square error between haemodynamic wall parameters was comparable to the range of the expected variability of each imaging technique (WSS: 0.411 N m(-2); OSI: 0.048; temporal WSSG: 150 N s(-1) m(-2); spatial WSSG: 2.29 N m(-3); WSSAG: 87.6 rad m(-1)). In conclusion, MRI and 3DUS are capable of providing haemodynamic parameters when combined with CFD, and the predictions are in most cases qualitatively and quantitatively similar. The relatively high cost of MRI and continuing improvement in ultrasound favour US to MRI for future haemodynamic studies of superficial arteries.
Assuntos
Algoritmos , Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Carótidas/diagnóstico por imagem , Artérias Carótidas/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Modelos Cardiovasculares , Adulto , Artérias Carótidas/anatomia & histologia , Simulação por Computador , Ecocardiografia Tridimensional/métodos , Feminino , Humanos , Armazenamento e Recuperação da Informação/métodos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
The link between atherosclerosis and wall shear stress (WSS) has lead to considerable interest in the in vivo estimation of WSS. Both magnetic resonance imaging (MRI) and three-dimensional ultrasound (3DUS) are capable of providing the anatomical and flow data required for subject-specific computational fluid dynamics (CFD) simulations. This study compares, for the first time, predicted 3D flow patterns based on black blood MRI and 3DUS. Velocity fields in the carotid arteries of nine subjects have been reconstructed, and the haemodynamic wall parameters WSS, oscillatory shear index (OSI), WSS gradients (WSSG) and angle gradients (WSSAG) were computed and compared. There was a good qualitative agreement between results derived from MRI and 3DUS, embodied by a strong linear correlation between the patched representations of the haemodynamic wall parameters. The root-mean-square error between haemodynamic wall parameters was comparable to the range of the expected variability of each imaging technique (WSS: 0.411 N/m; OSI: 0.048; temporal WSSG: 2.29 N/(s.m/sup 2/); spatial WSSG: 150 N/m/sup 3/; WSSAG: 87.6 rad/m). In conclusion, MRI and 3DUS are comparable techniques for combining with CFD in the carotid artery. The relatively high cost of MRI favour 3DUS to MRI for future haemodynamic studies of superficial arteries.
RESUMO
The importance of shear stress in the initiation and progression of atherosclerosis has been recognized for some time. A novel way to quantify wall shear stress under physiologically realistic conditions is to combine magnetic resonance imaging (MRI) and computational fluid dynamics. The present study aims to investigate the reproducibility of the simulated flow by using this combined approach. The right carotid bifurcations of eight healthy subjects were scanned twice with MRI within a few weeks. Three-dimensional geometries of the vessels were reconstructed for each scan and each subject. Pulsatile flows through these models were calculated to assess errors associated with the predicted flow parameters. This was done by comparing various wall shear stress indices, including the time-averaged wall shear stress (WSS), oscillating shear index (OSI), WSS Gradients (WSSG) and WSS Angle Deviation (WSSAD). Qualitatively, all the wall shear parameters proved to be highly reproducible. Quantitatively, the reproducibility was over 90% for OSI and WSSAD, but less impressive (60%) for other parameters. Our results indicated that WSS and WSSG values were extremely sensitive to subtle variations in local geometry and mesh design, particularly in regions around the bifurcation apex where WSS values were high and least reproducible.
Assuntos
Artérias/fisiologia , Hemorreologia/métodos , Imageamento Tridimensional/métodos , Imagem Cinética por Ressonância Magnética/métodos , Modelos Cardiovasculares , Adulto , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Simulação por Computador , Vasos Coronários/fisiologia , Feminino , Análise de Elementos Finitos , Humanos , Masculino , Fluxo Pulsátil , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Resistência ao CisalhamentoRESUMO
The combined magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) modeling approach is playing an increasingly important role in advancing our understanding of the relationship between hemodynamics and arterial disease. Nevertheless, such a modeling approach involves a number of uncertainties associated with various stages of the process. The present study is concerned with the reproducibility of geometry reconstruction, one of the most crucial steps in the modeling process. The reproducibility test was conducted on the right carotid bifurcation of eight normal human subjects, each of whom were scanned twice using the same MR protocol with an in-plane resolution of 0.625 mm. Models constructed from different scans of the same subject were compared and assessed using four quantitative measures: centerline distance, cross-sectional area, contour shape factors, and mean radius difference. The difference in the maximum carotid bulb area between the two scans was found to be <8.1% for all subjects. Shape factors (measuring the dissimilarity between two contours) of <10% were achieved in most of the common carotid arteries (CCAs) and internal carotid arteries (ICAs). The mean radius difference between the two scans was <0.4 mm for all subjects. Among the three vessels, the geometry of CCA was well reproduced by the reconstruction procedure in most of the cases, while the external carotid artery (ECA) showed the worst reproducibility. The impact of geometrical differences on CFD-predicted flow patterns and wall shear stress (WSS) will be investigated and discussed in a separate paper.
Assuntos
Artérias Carótidas/anatomia & histologia , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética , Adulto , Simulação por Computador , Feminino , Humanos , Imageamento Tridimensional , Masculino , Modelos Anatômicos , Reprodutibilidade dos TestesRESUMO
Image-based Computational Fluid Dynamics (CFD) has become a popular tool for the prediction of in vivo flow profiles and hemodynamic wall parameters. Currently, Magnetic Resonance Imaging (MRI) is most widely used for in vivo geometry acquisition. For superficial arteries such as the carotids and the femoral artery, three-dimensional (3-D) extravascular ultrasound (3-DUS) could be a cost-effective alternative to MRI. In this study, nine healthy subjects were scanned both with MRI and 3-DUS. The reconstructed carotid artery geometries for each subject were compared by evaluating cross-sectional areas, centerlines, and carotid nonplanarity. Lumen areas agreed very well between the two different acquisition techniques, whereas centerlines and nonplanarity parameters showed measurable disagreement, possibly due to the different neck and head positions adopted for 3-DUS versus MRI. With the current level of agreement achieved, 3-DUS has the potential to become an inexpensive and fast alternative to MRI for image-based CFD modeling of superficial arteries.
Assuntos
Anatomia Transversal/métodos , Artérias Carótidas/anatomia & histologia , Artérias Carótidas/diagnóstico por imagem , Ecocardiografia Tridimensional/métodos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Técnica de SubtraçãoRESUMO
Fluid shear stress and mechanical wall stress may play a role in the formation of early atherosclerotic lesions, but these quantities are difficult to measure in vivo. Our objective was to quantify these parameters in normal subjects in a clinical setting, and to define regions of low wall shear stress and high mechanical stress. The right carotid bifurcations of five healthy male volunteers were investigated using a novel non-invasive technique which integrates magnetic resonance angiography, ultrasonography, tonometry and state-of-the-art computational fluid dynamics and solid mechanics models. Significant inter-subject variations in patterns as well as magnitude of wall shear stress and mechanical stress were found. In spite of individual variabilities, this study revealed that some regions of the artery wall are exposed simultaneously to low wall shear stress and high mechanical stress and that these regions correspond to areas where atherosclerotic plaque develops. The coexistence of regions of low wall shear stress and high tensile stress may be an important determinant of the formation of atheroma in human arteries.
Assuntos
Artéria Carótida Primitiva/fisiologia , Imageamento Tridimensional/métodos , Modelos Cardiovasculares , Adulto , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Artéria Carótida Primitiva/anatomia & histologia , Artéria Carótida Primitiva/ultraestrutura , Artéria Carótida Interna , Simulação por Computador , Humanos , Imageamento por Ressonância Magnética , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Estresse Mecânico , Túnica Íntima/anatomia & histologia , Túnica Íntima/diagnóstico por imagem , Túnica Íntima/fisiologia , Túnica Média/anatomia & histologia , Túnica Média/diagnóstico por imagem , Túnica Média/fisiologia , UltrassonografiaRESUMO
Despite normal indices of left ventricular (LV) chamber function, patients with LV hypertrophy (LVH) due to hypertension are thought to have depressed midwall systolic shortening compared with normotensives. The aims of the present study were (1) to confirm this observation and (2) to assess the effects of antihypertensive therapy that cause regression of LVH on LV systolic function assessed at both the midwall and endocardium. Thirty-eight previously untreated hypertensive subjects with LVH underwent echocardiography and were compared with 38 normotensive control subjects. Comparisons between the group with LVH and the control group revealed no significant differences in cardiac output (4. 32+/-0.23 versus 4.55+/-0.21 L/min), ejection fraction (62.5+/-2% versus 66.4+/-1.07%), or endocardial fractional shortening (34.5+/-1.45% versus 37.0+/-0.82%), but shortening assessed at the midwall was significantly less in the group with LVH (17.9+/-1.11% versus 21.6+/-0.63%, P<0.01). Subsequently, 32 patients with uncontrolled hypertension (24 previously untreated and 8 on existing antihypertensive therapy) underwent treatment with ramipril, with the addition of felodipine and bendrofluazide if required, to reduce blood pressure to <140/90 mm Hg. These 32 patients underwent echocardiography at baseline, after blood pressure control, and after an additional 6 months of tight blood pressure control. Good blood pressure control was achieved after 6 months compared with baseline (143/86+/-2.8/1.4 versus 174/103+/-4.1/1.9 mm Hg; P<0.01) with significant regression of LV mass index (124+/-3.4 versus 145+/-3.8 g/m(2), P<0.01). LV fractional shortening assessed at the midwall improved with regression of LVH (21.9+/-0.84 and 18.7+/-1. 19%, P<0.05), with posttreatment midwall shortening being similar to that of the normal control subjects evaluated in the first study. Hypertensive patients with LVH have depressed midwall systolic shortening despite normal indices of LV chamber function. Regression of LVH after good blood pressure control improved midwall shortening to normal levels.
Assuntos
Coração/fisiopatologia , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/tratamento farmacológico , Hipertrofia Ventricular Esquerda/fisiopatologia , Adulto , Anti-Hipertensivos/farmacologia , Anti-Hipertensivos/uso terapêutico , Bendroflumetiazida/farmacologia , Bendroflumetiazida/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Débito Cardíaco/efeitos dos fármacos , Débito Cardíaco/fisiologia , Ecocardiografia/efeitos dos fármacos , Endocárdio/fisiologia , Felodipino/farmacologia , Felodipino/uso terapêutico , Feminino , Septos Cardíacos/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Contração Miocárdica/fisiologia , Ramipril/farmacologia , Ramipril/uso terapêutico , Função Ventricular Esquerda/efeitos dos fármacosRESUMO
Short-term studies of GH replacement in adult hypopituitarism have usually demonstrated beneficial effects on body composition and circulating lipids, with neutral or occasionally adverse effects on glucose tolerance. Fasting hyperinsulinemia has been reported. GH effects on cardiac function have been variable. The effects of long-term GH therapy, taking into account the consequences of increasing age, are not fully known. Thirty-three hypopituitary, initially middle-aged adults were studied over a 7-yr period; 12 patients took GH therapy (mean, 0.7 mg daily) continuously (group A); 11 took GH for only 6-18 months, a minimum of 5 yr previously (group B); and 10 patients never received GH therapy (group C). Other pituitary replacement was maintained. Effects on anthropometry, body composition (by bioimpedance analysis, total body potassium, and dual energy x-ray absorptiometry), circulating lipids, glucose and insulin concentrations, cardiac 2-dimensional and Doppler echocardiography, and exercise tolerance were assessed before and after the treatment period. Continuous GH therapy had no significant effect on body weight, but it prevented the increase in waist circumference and waist to hip ratio that occurred in the patients without GH substitution (waist to hip ratio, group A, 0.87+/-0.08 at baseline, 0.85+/-0.09 at 7 yr; group B, 0.89+/-0.11 at baseline, 0.94+/-0.11 at 7 yr; P < 0.005 for GH effect; group C, 0.87+/-0.10 at baseline, 0.92+/-0.10 at 7 yr; P < 0.005 for GH effect). A GH-induced decrease in subscapular skinfold thickness was also observed. By bioimpedance analysis, GH therapy caused an increase in total body water and fat-free mass, and a decrease in the percent body fat. Although changes occurred with time in all groups, no significant additional GH therapy effects were observed on glucose tolerance, insulin concentrations, lipid levels, cardiac dimensions, echocardiographic diastolic function, or exercise tolerance. In conclusion, prolonged GH substitution in middle-aged hypopituitary adults causes a sustained improvement in body composition. Other benefits, e.g. on lipid levels and exercise tolerance, were not apparent at 7 yr when comparisons were made with GH-untreated hypopituitary controls. Potentially adverse effects on glucose tolerance and insulinemia did not develop with prolonged GH therapy.
Assuntos
Hormônio do Crescimento/uso terapêutico , Hipopituitarismo/tratamento farmacológico , Absorciometria de Fóton , Glicemia/metabolismo , Pressão Sanguínea/fisiologia , Composição Corporal/efeitos dos fármacos , Estatura/fisiologia , Índice de Massa Corporal , Peso Corporal/fisiologia , Metabolismo dos Carboidratos , Ecocardiografia Doppler , Feminino , Seguimentos , Coração/fisiologia , Frequência Cardíaca/fisiologia , Terapia de Reposição Hormonal , Humanos , Hipopituitarismo/metabolismo , Hipopituitarismo/fisiopatologia , Metabolismo dos Lipídeos , Masculino , Pessoa de Meia-Idade , Potássio/sangueRESUMO
Exercise treadmill electrocardiography and myocardial perfusion imaging are commonly used in non-invasive tests for the detection of myocardial ischaemia. Unfortunately there are limitations in the assessment of hypertensive patients since these tests frequently provide false-positive results, particularly in those subjects with left ventricular hypertrophy. In order to investigate the utility of stress echocardiography in hypertensive patients we assessed 173 subjects undergoing this investigation in our department. Of these, 66 had had coronary angiography within 6 months. Thirty subjects were hypertensives, 17 with left ventricular hypertrophy, and 36 normotensives. Patients with a 70% or greater stenosis at coronary angiography were deemed to have sufficient disease to cause myocardial ischaemia. The overall sensitivity of stress echocardiography for detecting myocardial ischaemia was 83% with a specificity of 77%. For the hypertensive group alone the sensitivity was 93% and specificity 73%. The normotensives had a sensitivity of 76% with a specificity of 80%. In conclusion, in this group of hypertensives stress echocardiography had a favourable specificity and this was not significantly different from that of normotensive subjects. Journal of Human Hypertension (2000) 14, 399-401
Assuntos
Ecocardiografia/métodos , Hipertensão/complicações , Isquemia Miocárdica/diagnóstico por imagem , Angiografia Coronária , Dobutamina , Teste de Esforço , Feminino , Humanos , Masculino , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/etiologia , Valores de Referência , Sensibilidade e EspecificidadeRESUMO
The pulsatile flow in an anatomically realistic compliant human carotid bifurcation was simulated numerically. Pressure and mass flow waveforms in the carotid arteries were obtained from an individual subject using non-invasive techniques. The geometry of the computational model was reconstructed from magnetic resonance angiograms. Maps of time-average wall shear stress, contours of velocity in the flow field as well as wall movement and tensile stress on the arterial wall are all presented. Inconsistent with previous findings from idealised geometry models, flow in the carotid sinus is dominated by a strong helical flow accompanied by a single secondary vortex motion. This type of flow is induced primarily by the asymmetry and curvature of the in vivo geometry. Flow simulations have been carried out under the rigid wall assumption and for the compliant wall, respectively. Comparison of the results demonstrates the quantitative influence of the vessel wall motion. Generally there is a reduction in the magnitude of wall shear stress, with its degree depending on location and phase of the cardiac cycle. The region of slow or reversed flow was greater, in both spatial and temporal terms in the compliant model, but the global characteristics of the flow and stress patterns remain unchanged. The analysis of mechanical stresses on the vessel surface shows a complicated stress field. Stress concentration occurs at both the anterior and posterior aspects of the proximal internal bulb. These are also regions of low wall shear stress. The comparison of computed and measured wall movement generally shows good agreement.
Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Carótidas/anatomia & histologia , Artérias Carótidas/fisiologia , Modelos Cardiovasculares , Algoritmos , Elasticidade , Análise de Elementos Finitos , Fricção , Hemodinâmica/fisiologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética , Masculino , Movimento , Fatores de Tempo , Tonometria Ocular , Ultrassonografia Doppler de PulsoRESUMO
The carotid bifurcation is a common site for clinically significant atherosclerosis, and the development of this disease may be influenced by the local hemodynamic environment. It has been shown that vessel geometry and pulsatile flow conditions are the predominant factors that determine the detailed blood flow patterns at the carotid bifurcation. This study was initiated to quantify the velocity profiles and wall shear stress (WSS) distributions in an anatomically true model of the human carotid bifurcation using data acquired from magnetic resonance (MR) imaging scans of an individual subject. A numerical simulation approach combining the image processing and computational fluid dynamics (CFD) techniques was developed. Individual vascular anatomy and pulsatile flow conditions were all incorporated into the computer model. It was found that the geometry of the carotid bifurcation was highly complex, involving helical curvature and out-of-plane branching. These geometrical features resulted in patterns of flow and wall shear stress significantly different from those found in simplified planar carotid bifurcation models. Comparisons between the predicted flow patterns and MR measurement demonstrated good quantitative agreement.
Assuntos
Estenose das Carótidas/diagnóstico , Hemodinâmica/fisiologia , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Arteriosclerose/diagnóstico , Arteriosclerose/fisiopatologia , Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Carótidas/patologia , Artérias Carótidas/fisiopatologia , Estenose das Carótidas/fisiopatologia , Simulação por Computador , Diástole/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Pulsátil/fisiologia , Valores de Referência , Sístole/fisiologiaRESUMO
Fourteen cases had early fetal blood sampling (FBS) performed between 13 and 18 weeks gestation in the Antenatal Diagnostic Centre, National University Hospital, Singapore from Jan 1988 to December 1994. The indications were: a) ultrasound abnormality (n = 6), b) hydrops (n = 1), c) screening for blood disorders (n = 2), d) amnio results inconclusive or to confirm abnormal amnio results (n = 5). This article analyses retrospectively the early FBS procedure and its outcome. There were no procedure related fetal losses in this study. The reliable rapid results obtained following the procedure enabled the obstetrician to counsel the couple regarding the current pregnancy and advise them accordingly for the subsequent pregnancy. Thus we found it useful not only in our patients but also for patients from overseas who get their results within a week to plan their stay.