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Frank E Rademakers

Publications and source records attributed to Frank E Rademakers.

16 recordsLinked to original sources
PubMed2006

Determination of interobserver variability for identifying inducible left ventricular wall motion abnormalities during dobutamine stress magnetic resonance imaging.

AIMS: To determine the interobserver variability for identifying inducible left ventricular (LV) wall motion abnormalities during high-dose dobutamine/atropine stress cardiovascular magnetic resonance (DSMR). METHODS AND RESULTS: Four readers from various institutions were supplied with the image data from 150 consecutive DSMR examinations and asked to grade wall motion and image quality throughout graded doses of dobutamine infusion administered to achieve 85% of the maximum age-predicted heart rate. Inducible ischaemia was identified if more than one segment demonstrated a new or worsening LV wall motion abnormality, and significant stenosis was defined as > or =50% luminal diameter reduction by quantitative contrast coronary angiography. Seventy-seven patients (51%) had luminal narrowings > or =50%. Diagnostic performance (sensitivity, specificity, diagnostic accuracy) of all readers was 78.2, 87.0 and 82.5%. Disagreement between two readers occurred in every seventh examination. Agreement on the presence or absence of inducible wall motion abnormalities was moderate (mean kappa value 0.59, range 0.52-0.76). Diagnostic performance and disagreement were independent of the presence of luminal narrowings > or =50% or the number of diseased coronary vessels. Image quality was regarded excellent in 89.3% of standard views. CONCLUSION: In the setting of multiple observers from different institutions performing a diagnostic reading of DSMR examinations carried out at a single centre, the interobserver variability was low for identifying inducible LV wall motion abnormalities indicative of coronary arterial luminal narrowings > or =50%.

Cardiotonic Agents↗
PubMed2006

Longitudinal but not circumferential deformation reflects global contractile function in the right ventricle with open pericardium.

The clinical evaluation of right ventricular (RV) contractility is problematic because instantaneous RV volumetry is difficult to achieve. Our aim was to test whether global RV contractility can be assessed by using regional indexes in the longitudinal and/or circumferential axis. Six anesthetized adult ewes were instrumented with a RV conductance catheter and four RV free wall sonomicrometry crystals (interrogating the longitudinal and circumferential axes). Global and regional preload recruitable stroke work (PRSW) were measured by using acute vena cava occlusions at baseline, during esmolol and dobutamine infusion, and during stable low-preload and high-afterload conditions. The agreement between regional and global PRSW was assessed with regression and Bland-Altman analysis. Both regional PRSW indexes correlated well with global PRSW in baseline conditions, during inotropic modulation (R(2) = 0.83 and 0.74 for longitudinal and circumferential regional PRSW, respectively), and during preload reduction (R(2) = 0.62 and 0.83, respectively), but only longitudinal regional PRSW correlated with global PRSW in increased afterload conditions (R(2) = 0.59 and 0.13 for longitudinal and circumferential regional PRSW, respectively). We conclude that in the open-chest, open-pericardium animal model, deformation in the longitudinal axis accurately reflects global RV contractile function in baseline conditions and during acute load modulation, whereas circumferential motion is influenced by changes in afterload.

Adrenergic beta-Antagonists↗
PubMed2006

Experimental assessment of a new research tool for the estimation of two-dimensional myocardial strain.

One-dimensional strain imaging has been shown to be angle dependent. To address this problem, a new methodology, 2D-strain, has become available. The aim of this study was to validate this methodology in an in vivo set-up against sonomicrometry. In five open chest sheep, ultrasound gray-scale images were acquired of the inferolateral wall from two different angles. The longitudinal and radial strain components were simultaneously extracted using the novel 2D-strain methodology. The extracted values were compared with sonomicrometry using Bland-Altman statistics and correlation coefficients. A good agreement was found for the longitudinal strain component, while, for the radial strain estimates, the accuracy was less. 2D-strain is a fast and accurate tool to assess longitudinal strain from apical views. Further improvements are needed for the method to be sufficiently accurate in estimating the deformation perpendicular or close to perpendicular to the ultrasound beam.

Animals↗
PubMed2005

Assessment of ventricular coupling with real-time cine MRI and its value to differentiate constrictive pericarditis from restrictive cardiomyopathy.

The purpose of this study was to evaluate the use of respiratory-related ventricular coupling to differentiate patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). In 18 histologically proven cases of CP, 6 patients with inflammatory pericarditis (IP), 15 RCM patients and 17 normal subjects, real-time cine MRI was performed in the cardiac short-axis (basal half of the ventricles) during operator-guided deep respiration. The images were analyzed for ventricular septal position and shape during early ventricular filling. Early diastolic septal inversion (I) or flattening (F) was found in all CP (I:15,F:3), and in all IP (I:2,F:4), but seldom in normals (F:1) and not in RCM. The septal abnormalities occurred at the onset of inspiration and rapidly disappeared with the next heartbeats. The amount of ventricular coupling was evaluated by quantifying the difference in the maximal septal excursion between inspiration and expiration. This parameter, normalized to the biventricular diameter, was significantly larger in CP (20.0+/-4.5%, P<0.0001) and IP (14.8+/-3.2%, P<0.0001) patients than in normals (7.0+/-2.4%), whereas RCM patients had a trend toward decreased excursion (4.2+/-1.7%, P=0.11). A cut-off value of 11.8% (mean normals +2 SD) enabled to differentiate CP patients from normals and RCM patients completely. Real-time cine MRI can easily depict increased ventricular coupling, which may be helpful to better differentiate between CP and RCM patients, especially in patients with normal or minimally thickened pericardium. The increase in coupling in IP patients is likely caused by decreased compliance of the inflamed pericardial layers.

Aged↗
PubMed2004

Bringing the heart into focus: a perspective on non-invasive cardiac imaging.

Non-invasive cardiac imaging is already a cornerstone of cardiac diagnostics and will play an increasingly important role also in preventive and therapeutic cardiology. Several modalities can be used (echocardiography, nuclear, CT, CMR) and there is a need to study the respective role of these techniques in clinical practice and to anticipate on developments in the near future.

Diagnostic Imaging↗
PubMed2003

Clinically suspected constrictive pericarditis: MR imaging assessment of ventricular septal motion and configuration in patients and healthy subjects.

PURPOSE: To assess ventricular septal motion and quantify the septal configuration in patients clinically suspected of having constrictive pericarditis (CP), and to compare these patients with healthy subjects and with patients who have other diastolic heart abnormalities such as restrictive cardiomyopathy (RCM). MATERIALS AND METHODS: In 41 patients clinically suspected of having CP and 12 healthy subjects, magnetic resonance (MR) imaging yielded information about cardiac morphology and function. On short-axis cine MR images, septal motion was assessed, and the septal and left ventricular free wall (LVFW) radii of curvature were quantified and normalized to end systole. Abnormal diastolic septal motion was expressed in terms of the largest difference in normalized radius between the septum and the LVFW. Analysis of variance was used to identify significant differences in septal shape among subject groups. RESULTS: Left-sided septal flattening was identified in 17 of the 21 patients with surgically proven CP, in none of the 20 patients without CP, and in none of the healthy subjects. CP without septal flattening was present on the left side (n = 1), on the right side (n = 1), and at the atrioventricular grooves (n = 2). Abnormal septal motion yielded a sensitivity of 81% (17 of 21 patients), specificity of 100% (20 of 20 patients), accuracy of 90% (37 of 41 patients), positive predictive value of 100% (17 of 17 patients), and negative predictive value of 83% (20 of 24 patients) in the detection of CP. The maximal difference in normalized radius of curvature between the septum and the LVFW in the patients with CP was significantly different from that in the patients without CP (P <.001) and that in the healthy subjects (P <.001). CONCLUSION: Abnormal diastolic septal motion is a frequent phenomenon of CP. If present in patients suspected of having CP, this finding is helpful in distinguishing CP from RCM.

Adult↗
PubMed2003

Coronary artery imaging with real-time navigator three-dimensional turbo-field-echo MR coronary angiography: initial experience.

PURPOSE: To examine the value of a commercially available three-dimensional (3D) real-time navigator magnetic resonance (MR) coronary angiographic examination for detection of significant coronary artery stenoses, with conventional coronary angiography as the standard of reference. MATERIALS AND METHODS: Twenty-one patients underwent 3D navigator MR coronary angiography immediately before catheterization. Two observers independently graded image quality on a scale from 1 (unreadable) to 5 (excellent), quantified coronary artery visualization, and evaluated the presence of significant (ie, >50% narrowing) stenoses. kappa statistics were used to assess interobserver agreement, and receiver operating characteristic (ROC) analysis was used to assess stenosis detection. RESULTS: For two of 21 patients, MR coronary angiogram quality was insufficient for analysis (mean score < 2). For the remaining 19 patients, the mean image quality scores assigned by observers 1 and 2 were 3.3 +/- 1.0 (SD) and 3.2 +/- 0.9, respectively. A mean of 71% of all coronary artery segments were visible at MR coronary angiography, and there was 91% agreement between the observers (kappa = 0.78). Observers 1 and 2 detected significant stenoses (n = 29) at MR coronary angiography with sensitivities of 44.4% and 55.5%, respectively; specificities of 95.1% and 83.7%, respectively; and 80% agreement (kappa = 0.35). Areas under the ROC curve were 0.817 and 0.795 for observers 1 and 2, respectively. CONCLUSION: Large portions of the coronary arteries can be visualized with MR coronary angiography. Imaging results are not consistently reliable, however. The examination is premature for routine clinical assessment of significant coronary artery stenosis owing to low sensitivity and large observer variability.

Adult↗
PubMed2003

Absent right and persistent left superior vena cava.

A patient is described presenting with atrial fibrillation. A dilated coronary sinus was found due to the presence of a persistent left superior caval vein. Absence of the right superior caval vein was suspected with contrast injection through an i.v. line in the right arm, and was confirmed with phlebography. No associated cardiac anomalies were found. Persistent left superior vena cava is a common anomaly, although simultaneous complete absence of the right superior vena cava is rare. The incidence, embryology, diagnosis and importance of this anomaly is discussed.

Atrial Fibrillation↗
PubMed2002

Visualization of ventricular thrombi with contrast-enhanced magnetic resonance imaging in patients with ischemic heart disease.

BACKGROUND: Ventricular thrombus formation is a frequent and potentially dangerous complication in patients with ischemic heart disease. Although transthoracic echocardiography (TTE) is generally used as diagnostic technique, we explored the role of contrast-enhanced (CE)-MRI to detect ventricular thrombi. METHODS AND RESULTS: In 57 patients with acute myocardial infarction, chronic myocardial infarction, or ischemic cardiomyopathy, MRI was performed to evaluate ventricular function (CINE-MRI) and to depict presence of myocardial necrosis and/or scarring and no-reflow areas (CE-MRI). All studies were analyzed for concomitant ventricular thrombi. CE-MRI depicted 12 mural thrombi (3.1+/-2.9 cm3), located in left ventricular (LV) apex or adherent to anteroseptum, presenting as black, well-defined structures surrounded by bright contrast-enhanced blood. Thrombus formation on CE-MRI was related to larger end-diastolic volumes; lower ejection fractions; the region of delayed enhancement and lowest wall motion score, especially in left anterior descending coronary artery territory; and LV aneurysm formation. On CINE-MRI, thrombi were found in 6 patients. Nonvisualized thrombi were usually small (mean size 1.2+/-0.7 cm3). TTE depicted thrombi in 5. Nonvisualized lesions were most frequently located in LV apex and had a larger size than nonvisualized lesions on CINE-MRI (3.0+/-3.2 cm3). In 3 patients with suspected apical thrombus on TTE, MRI was normal. CONCLUSIONS: CE-MRI is not only an excellent technique to depict myocardial necrosis and scar tissue in patients with ischemic heart disease, but this study also suggests a better identification of LV thrombi than with presently used clinical imaging modalities, such as TTE.

Acute Disease↗
PubMed2002

Myocardial function defined by strain rate and strain during alterations in inotropic states and heart rate.

For porcine myocardium, ultrasonic regional deformation parameters, systolic strain (epsilon(sys)) and peak systolic strain rate (SR(sys)), were compared with stroke volume (SV) and contractility [contractility index (CI)] measured as the ratio of end-systolic strain to end-systolic wall stress. Heart rate (HR) and contractility were varied by atrial pacing (AP = 120-180 beats/min, n = 7), incremental dobutamine infusion (DI = 2.5-20 microg. kg(-1). min(-1), n = 7), or continuous esmolol infusion (0.5 mg. kg(-1). min(-1)) + subsequent pacing (120-180 beats/min) (EI group, n = 6). Baseline SR(sys) and epsilon(sys) averaged 5.0 +/- 0.4 s(-1) and 60 +/- 4%. SR(sys) and CI increased linearly with DI (20 microg. kg(-1). min(-1); SR(sys) = 9.9 +/- 0.7 s(-1), P < 0.0001) and decreased with EI (SR(sys) = 3.4 +/- 0.1 s(-1), P < 0.01). During pacing, SR(sys) and CI remained unchanged in the AP and EI groups. During DI, epsilon(sys) and SV initially increased (5 microg. kg(-1). min(-1); epsilon(sys) = 77 +/- 6%, P < 0.01) and then progressively returned to baseline. During EI, SV and epsilon(sys) decreased (epsilon(sys) = 38 +/- 2%, P < 0.001). Pacing also decreased SV and epsilon(sys) in the AP (180 beats/min; epsilon(sys) = 36 +/- 2%, P < 0.001) and EI groups (180 beats/min; epsilon(sys) = 25 +/- 3%, P < 0.001). Thus, for normal myocardium, SR(sys) reflects regional contractile function (being relatively independent of HR), whereas epsilon(sys) reflects changes in SV.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Cardiac dysfunction in heart failure with normal ejection fraction: MRI measurements.

Cardiovascular magnetic resonance is a non-invasive 3-dimensional imaging technique which can provide morphologic and functional information as well as tissue characterization without the use of ionizing radiation or nephrotoxic contrast agents. It has a high accuracy and reproducibility and is optimally suited to quantify structural and functional abnormalities and to follow a patient over time. In the setting of heart failure with normal ejection fraction it can be used as an alternative to echocardiography in those patients with suboptimal image quality but it can also provide unique information for the differential diagnosis and the underlying physiopathology of this syndrome.

Echocardiography↗