Ultrasound imaging in teaching cardiac physiology

This laboratory session provides hands-on experience for students to visualize the beating human heart with ultrasound imaging. Simple views are obtained from which students can directly measure important cardiac dimensions in systole and diastole. This allows students to derive, from first principles, important measures of cardiac function, such as stroke volume, ejection fraction, and cardiac output. By repeating the measurements from a subject after a brief exercise period, an increase in stroke volume and ejection fraction are easily demonstrable, potentially with or without an increase in left ventricular end-diastolic volume (which indicates preload). Thus, factors that affect cardiac performance can readily be discussed. This activity may be performed as a practical demonstration and visualized using an overhead projector or networked computers, concentrating on using the ultrasound images to teach basic physiological principles. This has proved to be highly popular with students, who reported a significant improvement in their understanding of Frank-Starling's law of the heart with ultrasound imaging.

MicroRNA signatures differentiate preserved from reduced ejection fraction heart failure

AIMS: Differentiation of heart failure with reduced (HFrEF) or preserved (HFpEF) ejection fraction independent of echocardiography is challenging in the community. Diagnostic strategies based on monitoring circulating microRNA (miRNA) levels may prove to be of clinical value in the near future. The aim of this study was to identify a novel miRNA signature that could be a useful HF diagnostic tool and provide valuable clinical information on whether a patient has HFrEF or HFpEF.

METHODS AND RESULTS: MiRNA biomarker discovery was carried out on three patient cohorts, no heart failure (no-HF), HFrEF, and HFpEF, using Taqman miRNA arrays. The top five miRNA candidates were selected based on differential expression in HFpEF and HFrEF (miR-30c, -146a, -221, -328, and -375), and their expression levels were also different between HF and no-HF. These selected miRNAs were further verified and validated in an independent cohort consisting of 225 patients. The discriminative value of BNP as a HF diagnostic could be improved by use in combination with any of the miRNA candidates alone or in a panel. Combinations of two or more miRNA candidates with BNP had the ability to improve significantly predictive models to distinguish HFpEF from HFrEF compared with using BNP alone (area under the receiver operating characteristic curve >0.82).

CONCLUSION: This study has shown for the first time that various miRNA combinations are useful biomarkers for HF, and also in the differentiation of HFpEF from HFrEF. The utility of these biomarker combinations can be altered by inclusion of natriuretic peptide. MiRNA biomarkers may support diagnostic strategies in subpopulations of patients with HF.

Exaggerated inflammation and monocytosis associate with diastolic dysfunction in heart failure with preserved ejection fraction: evidence of M2 macrophage activation in disease pathogenesis

BACKGROUND: Heart failure with preserved ejection fraction (HFPEF) is a major health problem associated with myocardial leukocyte infiltration, inflammation, and fibrosis. Monocyte and macrophage subsets play a role in HFPEF but have not been studied. We analyzed peripheral blood monocyte phenotype and plasma markers of monocyte activation in patients with HFPEF, asymptomatic LV diastolic dysfunction (aLVDD), and asymptomatic hypertension (aHTN).

METHODS AND RESULTS: Peripheral blood was collected from 23 aHTN, 30 aLVDD, and 30 HFPEF patients. Peripheral cytokines of classic/pro-inflammatory (tumor necrosis factor alpha, interleukin (IL) 12, IL-6, monocyte chemoattractant protein 1, C-X-C motif chemokine 10) and alternative/anti-inflammatory monocytes (chemokine-C-C motif ligand (CCL) 17, CCL-18, soluble CD163) were increased in aLVDD and HFPEF. Peripheral blood mononuclear cells and monocytes were purified and surface-stained for CD14, CD16, CD163, and CD206. Peripheral monocyte percentage was increased in aLVDD and HFPEF and correlated with echocardiographic LVDD indices. Classic/pro-inflammatory monocyte numbers were increased in aLVDD and HFPEF, and alternative/anti-inflammatory monocyte numbers were increased in HFPEF. CD163 M2-macrophage receptor was reduced in HFPEF. Culture of healthy donor monocytes (n = 3) with HFPEF patient-derived sera (n = 6) promoted M2 macrophage features as evidenced by altered morphology and genes (CD206, IL-10).

CONCLUSIONS: Increased peripheral inflammation, monocytosis, and monocyte differentiation to anti-inflammatory/profibrotic M2 macrophages likely associate with HFPEF and its precedent asymptomatic LVDD phase.

Associates of an elevated natriuretic peptide level in stable heart failure patients:implications for targeted management

BACKGROUND: Persistently elevated natriuretic peptide (NP) levels in heart failure (HF) patients are associated with impaired prognosis. Recent work suggests that NP-guided therapy can improve outcome, but the mechanisms behind an elevated BNP remain unclear. Among the potential stimuli for NP in clinically stable patients are persistent occult fluid overload, wall stress, inflammation, fibrosis, and ischemia. The purpose of this study was to identify associates of B-type natriuretic peptide (BNP) in a stable HF population.

METHODS: In a prospective observational study of 179 stable HF patients, the association between BNP and markers of collagen metabolism, inflammation, and Doppler-echocardiographic parameters including left ventricular ejection fraction (LVEF), left atrial volume index (LAVI), and E/e prime (E/e') was measured.

RESULTS: Univariable associates of elevated BNP were age, LVEF, LAVI, E/e', creatinine, and markers of collagen turnover. In a multiple linear regression model, age, creatinine, and LVEF remained significant associates of BNP. E/e' and markers of collagen turnover had a persistent impact on BNP independent of these covariates.

CONCLUSION: Multiple variables are associated with persistently elevated BNP levels in stable HF patients. Clarification of the relative importance of NP stimuli may help refine NP-guided therapy, potentially improving outcome for this at-risk population.

Long-term statin therapy in patients with systolic heart failure and normal cholesterol:effects on elevated serum markers of collagen turnover, inflammation, and B-type natriuretic peptide

BACKGROUND: The role of statin therapy in heart failure (HF) is unclear. The amino-terminal propeptide of procollagen type III (PIIINP) predicts outcome in HF, and yet there are conflicting reports of statin therapy effects on PIIINP.

OBJECTIVES: This study determined whether there was an increase in serum markers of inflammation, fibrosis (including PIIINP), and B-type natriuretic peptide (BNP) in patients with systolic HF and normal total cholesterol and determined the effects of long-term treatment with atorvastatin on these markers.

METHODS: Fifty-six white patients with systolic HF and normal cholesterol levels (age 72 [13] years; 68% male; body mass index 27.0 [7.3] kg/m(2); ejection fraction 35 [13]%; 46% with history of smoking) were randomly allocated to atorvastatin treatment for 6 months, titrated to 40 mg/d (A group) or not (C group). Age- and/or sex-matched subjects without HF (N group) were also recruited. Biomarkers were measured at baseline (all groups) and 6 months (A and C groups).

RESULTS: Serum markers of collagen turnover, inflammation, and BNP were significantly elevated in HF patients compared with normal participants (all P < 0.05). There were correlations between these markers in HF patients but not in normal subjects. Atorvastatin treatment for 6 months caused a significant reduction in the following biomarkers compared with baseline: BNP, from median (interquartile range) 268 (190-441) pg/mL to 185 (144-344) pg/mL; high-sensitivity C-reactive protein (hs-CRP), from 5.26 (1.95 -9.29) mg/L to 3.70 (2.34-6.81) mg/L; and PIIINP, from 4.65 (1.86) to 4.09 (1.25) pg/mL (all P < 0.05 baseline vs 6 months). Between-group differences were significant for PIIINP only (P = 0.027). There was a positive interaction between atorvastatin effects and baseline hs-CRP and PIIINP (P < 0.01).

CONCLUSIONS: Long-term statin therapy reduced PIIINP in this small, selected HF population with elevated baseline levels. Further evaluation of statin therapy in the management of HF patients with elevated PIIINP is warranted.

Murine Models of Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction

Left ventricular diastolic dysfunction leads to heart failure with preserved ejection fraction, an increasingly prevalent condition largely driven by modern day lifestyle risk factors. As heart failure with preserved ejection fraction accounts for almost one-half of all patients with heart failure, appropriate nonhuman animal models are required to improve our understanding of the pathophysiology of this syndrome and to provide a platform for preclinical investigation of potential therapies. Hypertension, obesity, and diabetes are major risk factors for diastolic dysfunction and heart failure with preserved ejection fraction. This review focuses on murine models reflecting this disease continuum driven by the aforementioned common risk factors. We describe various models of diastolic dysfunction and highlight models of heart failure with preserved ejection fraction reported in the literature. Strengths and weaknesses of the different models are discussed to provide an aid to translational scientists when selecting an appropriate model. We also bring attention to the fact that heart failure with preserved ejection fraction is difficult to diagnose in animal models and that, therefore, there is a paucity of well described animal models of this increasingly important condition.

Caractérisation d'IGFBP-2 comme biomarqueur intégrateur de la santé cardiométabolique

La protéine de liaison aux facteurs de croissance analogues à l’insuline (IGFBP)-2 est une protéine circulante fortement associée à la résistance à l’insuline qui module les effets métaboliques d’IGF-I et IGF-II en s’y associant directement, et qui exerce aussi des actions IGF-indépendantes via sa liaison à la matrice extracellulaire et aux intégrines. Chez l’homme, de faibles niveaux d’IGFBP-2 sont associés à un profil lipidique délétère, ainsi qu’à une augmentation de la masse grasse et de la résistance à l’insuline. Les travaux décrits dans cette thèse montrent chez l’humain et la souris que les niveaux d’IGFBP-2 sont associés de manière indépendante aux composantes du risque cardiométabolique. Chez l’homme, de faibles niveaux d’IGFBP-2 sont associés à la dyslipidémie athérogène. Une valeur seuil d’IGFBP-2 de 221.5 ng/mL a permis de discriminer entre les sujets métaboliquement sains et ceux répondant aux critères du syndrome métabolique. En plus de son association avec la résistance à l’insuline et les composantes du profil lipidique, de faibles niveaux d’IGFBP-2 sont associés à une fonction cardiaque diminuée chez les patients atteints de sténose aortique, tel qu’évaluée par le volume d’éjection indexé, un indice de fonction global du ventricule gauche qui intègre la fonction pompe et le remodelage du tissu. Chez l’homme, des niveaux d’IGFBP-2 élevés sont associés à un tissu adipeux brun plus volumineux ainsi qu’à une activité métabolique plus importante de ce dernier. Ces observations, telles qu’évaluées par PET/CT, sont aussi validées chez les souris surexprimant la forme humaine d’IGFBP-2. Nos travaux démontrent que les niveaux d’IGFBP-2 sont fortement associés au métabolisme des lipoprotéines et des lipides, à la fonction cardiaque ainsi qu’à l’activité du tissu adipeux brun. L’influence des niveaux d’IGFBP-2 par différentes altérations métaboliques menant à l’augmentation du risque cardiométabolique pourrait faire de ce dernier un biomarqueur précoce et intégrateur. Les travaux exposés dans la présente thèse soulignent aussi un rôle mécanistique potentiel pour IGFBP-2 dans la protection contre certaines altérations du métabolisme.

Cardiac magnetic resonance imaging in the diagnosis and determination of outcome of pulmonary hypertension

Pulmonary hypertension (PH) is a rare but serious condition that causes progressive right ventricular (RV) failure and death. PH may be idiopathic, associated with underlying connective-tissue disease or hypoxic lung disease, and is also increasingly being observed in the setting of heart failure with preserved ejection fraction (HFpEF). The management of PH has been revolutionised by the recent development of new disease-targeted therapies which are beneficial in pulmonary arterial hypertension (PAH), but can be potentially harmful in PH due to left heart disease, so accurate diagnosis and classification of patients is essential. These PAH therapies improve exercise capacity and pulmonary haemodynamics, but their overall effect on the right ventricle remains unclear. Current practice in the UK is to assess treatment response with 6-minute walk test and NYHA functional class, neither of which truly reflects RV function. Cardiac magnetic resonance (CMR) imaging has been established as the gold standard for the evaluation of right ventricular structure and function, but it also allows a non-invasive and accurate study of the left heart. The aims of this thesis were to investigate the use of CMR in the diagnosis of PH, in the assessment of treatment response, and in predicting survival in idiopathic and connective-tissue disease associated PAH. In Chapter 3, a left atrial volume (LAV) threshold of 43 ml/m2 measured with CMR was able to distinguish idiopathic PAH from PH due to HFpEF (sensitivity 97%, specificity 100%). In Chapter 4, disease-targeted PAH therapy resulted in significant improvements in RV and left ventricular ejection fraction (p<0.001 and p=0.0007, respectively), RV stroke volume index (p<0.0001), and left ventricular end-diastolic volume index (p=0.0015). These corresponded to observed improvements in functional class and exercise capacity, although correlation coefficients between Δ 6MWD and Δ RVEF or Δ LVEDV were low. Finally, in Chapter 5, one-year and three-year survival was worse in CTD-PAH (75% and 53%) than in IPAH (83% and 74%), despite similar baseline clinical characteristics, lung function, pulmonary haemodynamics and treatment. Baseline right ventricular stroke volume index was an independent predictor of survival in both conditions. The presence of LV systolic dysfunction was of prognostic significance in CTD-PAH but not IPAH, and a higher LAV was observed in CTD-PAH suggesting a potential contribution from LV diastolic dysfunction in this group.

Desenvolvimento de argamassa para restauração utilizando resíduo do polimento do porcelanato

The coatings mortars are essential elements of building structures because they execute an important role in protecting walls and are particularly exposed to aggressive action responsible for its degradation over time. The importance of wall coverings has been the subject of discussion and analysis in the conservation and rehabilitation of old buildings. Are sometimes removed and replaced with inappropriate solutions of constructive point of view or architecture. The most commonly used coatings on walls of old buildings is based on traditional hydraulic lime mortars. The present study aims at the formulation of new lime- based mortars and aerial fine aggregate, in order to contribute to a better field of conservation and restoration mortar coating of old buildings. Residue was used for polishing porcelain as fine aggregate, replacing the aggregate (sand), in percentages 05-30% by mass. We conducted a thorough evaluation of the mortar properties in fresh and hardened state by comparing the performance of the same with a reference mortar. The residue used was characterized as the density, bulk density, and particle size laser, scanning electron microscopy, X-ray diffraction and X-ray fluorescence. Formulations were produced 7, 6 with residue and one commonly used formulation, which served as a reference. In the formulations of lime mortars air (hydrated lime powder CH-I) has been adopted a stroke volume (1:3) with constant binder, was varied and the water / binder and aggregate and waste. For evaluation of mortars fresh, proceeded to consistency analysis, specific gravity, water retention and air content embedded. In the hardened state assays were performed in specific gravity, water retention, modulus of elasticity, tensile strength in bending, compressive strength, water absorption by capillary action, adhesion, tensile strength, resistance to shrinkage and salts by of crystallization trials with resources chloride solution, nitrate and sulfate all sodium in prismatic at 90 days of age, in addition to the micro structural analysis of mortars. Based on the results we can see that the mortar formulated with 10% content of waste and the reference free retraction feature more stable closer to neutrality. The composition of 10% was obtained better performance against the action of the salt crystallization. The mortar with 15% residue obtained better density, lower air content embedded and high capacity for water retention developing good workability. The replacement of 20% of waste generates a satisfactory utilization of resistance to compression, flexion and traction grip the base. And, finally, it can be seen that the mortar with 10, 15 and 20% residual show, in principle, good suitability as coatings, thus enabling a final result consistent with durability, workability and aesthetics developing therefore a material with better performance to repair or replace existing mortars in old buildings

Dinâmica fisiológica da variabilidade cardíaca: uma abordagem estatística na síncope vasovagal

Introdução: A perda transitória da consciência e tónus postural seguido de rápida recuperação é definida como síncope. Tem sido dada atenção a uma síncope de origem central com descida da pressão sistémica conhecida por síncope vasovagal (SVV). Objetivos: A análise da variabilidade da frequência cardíaca (HRV) é uma das principais estratégias para estudar a SVV através de protocolos padrão (por exemplo tilt test). O principal objetivo deste trabalho é compreender a importância relativa de diversas variáveis, tais como pressão arterial diastólica e sistólica, (dBP) e (sBP), volume sistólico (SV) e resistência periférica total (TPR) na HRV. Métodos: Foram usados modelos estatísticos mistos para modelar o comportamento das variáveis acima descritas na HRV. Analisaram-se mais de mil e quinhentas observações de quatro pacientes com SVV, previamente testados com análise espectral clássica para a fase basal (LF/HF=3.01) e fases de tilt (LF/HF=0.64), indicando uma predominância vagal no período tilt. Resultados: O modelo 1 revelou o papel importante da dBP e uma baixa influência de SV, na fase de tilt, relativos à HRV. No modelo 2 a TPR revelou uma baixa influência na HRV na fase de tilt entre os pacientes. Conclusões: Verificou-se que a HRV é influenciada por um conjunto de variáveis fisiológicas, cuja contribuição individual pode ser usada para compreender as flutuações cardíacas. O uso de modelos estatísticos salientou a importância de estudar o papel da dBP e SV na SVV.

The development of an algorithm to track blood pressure accurately based on the pulse transit time method

Oscillometric blood pressure (BP) monitors are currently used to diagnose hypertension both in home and clinical settings. These monitors take BP measurements once every 15 minutes over a 24 hour period and provide a reliable and accurate system that is minimally invasive. Although intermittent cuff measurements have proven to be a good indicator of BP, a continuous BP monitor is highly desirable for the diagnosis of hypertension and other cardiac diseases. However, no such devices currently exist. A novel algorithm has been developed based on the Pulse Transit Time (PTT) method, which would allow non-invasive and continuous BP measurement. PTT is defined as the time it takes the BP wave to propagate from the heart to a specified point on the body. After an initial BP measurement, PTT algorithms can track BP over short periods of time, known as calibration intervals. After this time has elapsed, a new BP measurement is required to recalibrate the algorithm. Using the PhysioNet database as a basis, the new algorithm was developed and tested using 15 patients, each tested 3 times over a period of 30 minutes. The predicted BP of the algorithm was compared to the arterial BP of each patient. It has been established that this new algorithm is capable of tracking BP over 12 minutes without the need for recalibration, using the BHS standard, a 100% improvement over what has been previously identified. The algorithm was incorporated into a new system based on its requirements and was tested using three volunteers. The results mirrored those previously observed, providing accurate BP measurements when a 12 minute calibration interval was used. This new system provides a significant improvement to the existing method allowing BP to be monitored continuously and non-invasively, on a beat-to-beat basis over 24 hours, adding major clinical and diagnostic value.

Seguridad del monitoreo hemodinámico invasivo versus mínimamente invasivo en pacientes con choque cardiogénico en cuidado intensivo adultos. Revisión sistemática

Introducción: El monitoreo hemodinámico es una herramienta para diagnosticar el choque cardiogénico y monitorear la respuesta al tratamiento; puede ser invasivo, mínimamente invasivo o no invasivo. Se realiza rutinariamente con catéter de arteria pulmonar (CAP) o catéter de Swan Ganz; nuevas técnicas de monitoreo hemodinámico mínimamente invasivo tienen menor tasa de complicaciones. Actualmente se desconoce cuál técnica de monitoreo cuenta con mayor seguridad en el paciente con choque cardiogénico. Objetivo: Evaluar la seguridad del monitoreo hemodinámico invasivo comparado con el mínimamente invasivo en pacientes con choque cardiogénico en cuidado intensivo adultos. Diseño: Revisión sistemática de la literatura. Búsqueda en Pubmed, EMBASE, OVID - Cochrane Library, Lilacs, Scielo, registros de ensayos clínicos, actas de conferencias, repositorios, búsqueda de literatura gris en Google Scholar, Teseo y Open Grey hasta agosto de 2016, publicados en inglés y español. Resultados: Se identificó un único estudio con 331 pacientes críticamente enfermos que comparó el monitoreo hemodinámico con CAP versus PiCCO que concluyó que después de la corrección de los factores de confusión, la elección del tipo de monitoreo no influyó en los resultados clínicos más importantes en términos de complicaciones y mortalidad. Dado que se incluyeron otros diagnósticos, no es posible extrapolar los resultados sólo a choque cardiogénico. Conclusión: En la literatura disponible no hay evidencia de que el monitoreo hemodinámico invasivo comparado con el mínimamente invasivo, en pacientes adultos críticamente enfermos con choque cardiogénico, tenga diferencias en cuanto a complicaciones y mortalidad.

Using historical lesion volume data in the design of a new phase II clinical trial in acute stroke

Background and Purpose-Clinical research into the treatment of acute stroke is complicated, is costly, and has often been unsuccessful. Developments in imaging technology based on computed tomography and magnetic resonance imaging scans offer opportunities for screening experimental therapies during phase II testing so as to deliver only the most promising interventions to phase III. We discuss the design and the appropriate sample size for phase II studies in stroke based on lesion volume. Methods-Determination of the relation between analyses of lesion volumes and of neurologic outcomes is illustrated using data from placebo trial patients from the Virtual International Stroke Trials Archive. The size of an effect on lesion volume that would lead to a clinically relevant treatment effect in terms of a measure, such as modified Rankin score (mRS), is found. The sample size to detect that magnitude of effect on lesion volume is then calculated. Simulation is used to evaluate different criteria for proceeding from phase II to phase III. Results-The odds ratios for mRS correspond roughly to the square root of odds ratios for lesion volume, implying that for equivalent power specifications, sample sizes based on lesion volumes should be about one fourth of those based on mRS. Relaxation of power requirements, appropriate for phase II, lead to further sample size reductions. For example, a phase III trial comparing a novel treatment with placebo with a total sample size of 1518 patients might be motivated from a phase II trial of 126 patients comparing the same 2 treatment arms. Discussion-Definitive phase III trials in stroke should aim to demonstrate significant effects of treatment on clinical outcomes. However, more direct outcomes such as lesion volume can be useful in phase II for determining whether such phase III trials should be undertaken in the first place. (Stroke. 2009;40:1347-1352.)

The World Stroke Organization and nursing [Guest Editorial]

The field of neuroscience nursing and, in particular, nursing people with stroke has evolved significantly over the past two decades. Nurses working with people who have had a stroke and their families are called upon to use advanced assessment skills, apply nursing diagnoses across the whole continuum of care, and identify and implement a wide range of interventions. Indeed, in a recent Canadian study on the implementation of stroke best practices, nurses were identified as playing a leading role in many aspects of stroke care and recovery. As the volume of research evidence across disciplines mounts, nurses are challenged to “keep up on the latest”...

Modern computed tomography techniques in stroke management

Technological development of fast multi-sectional, helical computed tomography (CT) scanners has allowed computed tomography perfusion (CTp) and angiography (CTA) in evaluating acute ischemic stroke. This study focuses on new multidetector computed tomography techniques, namely whole-brain and first-pass CT perfusion plus CTA of carotid arteries. Whole-brain CTp data is acquired during slow infusion of contrast material to achieve constant contrast concentration in the cerebral vasculature. From these data quantitative maps are constructed of perfused cerebral blood volume (pCBV). The probability curve of cerebral infarction as a function of normalized pCBV was determined in patients with acute ischemic stroke. Normalized pCBV, expressed as a percentage of contralateral normal brain pCBV, was determined in the infarction core and in regions just inside and outside the boundary between infarcted and noninfarcted brain. Corresponding probabilities of infarction were 0.99, 0.96, and 0.11, R² was 0.73, and differences in perfusion between core and inner and outer bands were highly significant. Thus a probability of infarction curve can help predict the likelihood of infarction as a function of percentage normalized pCBV. First-pass CT perfusion is based on continuous cine imaging over a selected brain area during a bolus injection of contrast. During its first passage, contrast material compartmentalizes in the intravascular space, resulting in transient tissue enhancement. Functional maps such as cerebral blood flow (CBF), and volume (CBV), and mean transit time (MTT) are then constructed. We compared the effects of three different iodine concentrations (300, 350, or 400 mg/mL) on peak enhancement of normal brain tissue and artery and vein, stratified by region-of-interest (ROI) location, in 102 patients within 3 hours of stroke onset. A monotonic increasing peak opacification was evident at all ROI locations, suggesting that CTp evaluation of patients with acute stroke is best performed with the highest available concentration of contrast agent. In another study we investigated whether lesion volumes on CBV, CBF, and MTT maps within 3 hours of stroke onset predict final infarct volume, and whether all these parameters are needed for triage to intravenous recombinant tissue plasminogen activator (IV-rtPA). The effect of IV-rtPA on the affected brain by measuring salvaged tissue volume in patients receiving IV-rtPA and in controls was investigated also. CBV lesion volume did not necessarily represent dead tissue. MTT lesion volume alone can serve to identify the upper size limit of the abnormally perfused brain, and those with IV-rtPA salvaged more brain than did controls. Carotid CTA was compared with carotid DSA in grading of stenosis in patients with stroke symptoms. In CTA, the grade of stenosis was determined by means of axial source and maximum intensity projection (MIP) images as well as a semiautomatic vessel analysis. CTA provides an adequate, less invasive alternative to conventional DSA, although tending to underestimate clinically relevant grades of stenosis.