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Biomedical subjects

E E Van der Wall

Publications and source records attributed to E E Van der Wall.

At least 19 recordsLinked to original sources
PubMed2004

Radiofrequency catheter ablation of ventricular tachycardia guided by intracardiac echocardiography.

AIMS: Ventricular tachycardia (VT) frequently has an anatomical substrate. Identification of areas prone to arrhythmogenicity facilitates radiofrequency catheter ablation (RFCA). Furthermore, direct monitoring of complications potentially increases safety of RFCA. The aim of this study was to evaluate the feasibility of guiding RFCA of VT with intracardiac echocardiography (ICE), in order to improve outcome and procedural safety. METHODS AND RESULTS: Eleven patients (age 59 +/- 15 years) with drug-refractory VT of various etiologies were studied. VT mapping and ablation were performed using standard techniques. ICE was performed with a multifrequency (5-10 MHz) phased-array transducer positioned in the right ventricle. Twenty different VTs were treated (CL 352 +/- 120 ms, 2.0 +/- 0.9 VT per patient). LV a- or dyskinesia was identified in all post-infarct patients. In patients with arrhythmogenic right ventricular dysplasia, right ventricular aneurysms and dyskinesia could be identified. In all patients catheter position and tip-tissue contact could easily be monitored with ICE. Procedural success (non-inducibility of hemodynamically stable VT) was achieved in all patients. Complications did not occur. CONCLUSION: ICE is feasible in guiding RFCA of VT of different etiologies. The use of ICE in adjunction with fluoroscopy and mapping procedures will facilitate treatment of VT and may contribute to the safety of the procedure.

Adult↗
PubMed2001

Perfusion and functional abnormalities outside the septal region in patients with left bundle branch block assessed with gated SPECT.

BACKGROUND: The presence of a left bundle branch block (LBBB) pattern on the electrocardiogram may frequently lead to perfusion defects in the septum not necessarily due to ischemic heart disease, but probably due to abnormal septal wall motion. The introduction of gated single photon emission computed tomography (SPECT) allows the evaluation of myocardial perfusion and function in one study. Accordingly, we analysed perfusion and function and the relation between perfusion and regional function in the septal region in patients with a LBBB without evidence of a previously sustained myocardial infarction. METHODS: We selected 37 patients with a LBBB without a history of a previous myocardial infarction, which was confirmed by echocardiography and/or coronary angiography. All patients underwent technetium-99m tetrofosmin gated SPECT myocardial imaging. Twelve control patients with a low likelihood of coronary artery disease and a normal technetium-99m tetrofosmin gated SPECT myocardial perfusion scintigram were selected as a reference population. The left ventricle (LV) was divided into 18 segments, which were scored for perfusion and function (wall motion and wall thickening) on a 4-point scale. RESULTS: The average LV end-diastolic volume was higher and the average LV ejection fraction was lower in patients with LBBB as compared to controls (142+/-90 vs. 81+/-18 ml, and 48+/-19 vs 62+/-7%, p=0.03 and p=0.02, respectively). Not only in the septum, but also in the other segments, reduced myocardial perfusion and abnormal wall motion/wall thickening was observed in the patients with LBBB (p<0.0001 vs controls). Patients with LBBB showed no correlation between perfusion and function in the septum, and between perfusion in septum and global LV function (r=0.21, p=0.2; r=0.10, p=0.6, respectively). Conversely, a good correlation was found between perfusion and function, either regional or global, in the remote segments (both r=0.79, p<0.0001). CONCLUSIONS: We conclude that patients with LBBB without a previous myocardial infarction show cardiomyopathic changes with perfusion and wall motion abnormalities, involving the entire left ventricle. The severity of diminished septal perfusion is not directly associated with the severity of septal wall motion abnormalities or global LV function. However, in the myocardial segments remote from the septum, reduced perfusion is closely associated with functional abnormalities.

Bundle-Branch Block↗
PubMed2000

Comparison of gated single-photon emission computed tomography with magnetic resonance imaging for evaluation of left ventricular function in ischemic cardiomyopathy.

To perform a head-to-head comparison between magnetic resonance imaging (MRI) and gated single-photon emission computed tomography (SPECT) for the evaluation of left ventricular (LV) function (LV ejection fraction [LVEF], LV volumes, and regional wall motion) in patients with ischemic cardiomyopathy, we studied 22 patients with chronic coronary artery disease and LV dysfunction. Multislice, multiphase echoplanar MRI was performed with Philips Gyroscan ACS-NT15. Image analysis was performed using the MASS software package to determine LV end-systolic volume, LV end-diastolic volume, and LVEF. The same parameters were calculated using quantitative gated SPECT software (QGS, Cedars-Sinai Medical Center). The different parameters were compared using linear regression, and correlation coefficients were calculated. Regional wall motion was also determined from both techniques, according to a 13-segment model and a 3-point scoring system (from 1 = normokinesia to 3 = akinesia or dyskinesia). A summed wall motion score was also calculated for MRI and gated SPECT. Good correlations were found between MRI and gated SPECT for all parameters: (1) summed wall motion scoreMRI versus summed wall motion scoreSPECT: y = 0.74x + 8.0, r = 0.88, p <0.01; (2) LV end-systolic volumeMRI versus LV end-systolic volumeSPECT: y = 0.94x - 12.3, r = 0.87, p <0.01; (3) LV end-diastolic volumeMRI versus LV end-diastolic volumeSPECT: y = 0.93x - 18.4, r = 0.84, p <0.01; and (4) LVEFMRI versus LVEFSPECT: y = 0.97x + 0.68, r = 0.90, p <0.01. For regional wall motion, an exact agreement of 83% was found, with a kappa statistic of 0.77 (95% confidence intervals 0.71 to 0.83, SE 0.03), indicating essentially excellent agreement. Thus, close and significant correlations were observed for assessment of LVEF, LV volumes, and regional wall motion by MRI and gated SPECT in patients with ischemic cardiomyopathy.

Aged↗
PubMed1999

Correlation of heart rate variability with cardiac functional and metabolic variables in cyclists with training induced left ventricular hypertrophy.

OBJECTIVE: To examine the correlation between heart rate variability and left ventricular mass in cyclists with an athlete's heart. METHODS: Left ventricular mass and diastolic function were determined at rest and myocardial high energy phosphates were quantified at rest and during atropine-dobutamine stress in 12 male cyclists and 10 control subjects, using magnetic resonance techniques. Ambulatory 24 hour ECG recordings were obtained, and time and frequency domain heart rate variability indices were computed. RESULTS: In the cyclists, the mean of all RR intervals between normal beats (meanNN), the SD of the RR intervals, and their coefficient of variation were significantly greater than in control subjects (p < 0.01, p < 0.01, and p < 0.05, respectively). For cyclists and control subjects, only meanNN correlated with left ventricular mass (r = 0.48, p = 0.038). The heart rate variability indices that correlated with functional or metabolic variables were: meanNN v E/A peak (the ratio of peak early and peak atrial filling rate) (r = 0.48, p = 0.039); the root mean square of successive differences in RR intervals among successive normal beats v E/A area (ratio of peak early and peak atrial filling volume) (r = 0.48, p = 0.040); percentage of successive RR intervals differing by more than 50 ms v the phosphocreatine to ATP ratio at rest (r = 0.54, p = 0. 017); and the SD of the average RR intervals during all five minute periods v the phosphocreatine to ATP ratio during stress (r = 0.60, p = 0.007). CONCLUSIONS: Highly trained cyclists have increased heart rate variability indices, reflecting increased cardiac vagal control compared with control subjects. Left ventricular mass has no major influence on heart rate variability, but heart rate variability is significantly correlated with high energy phosphate metabolism and diastolic function.

Adult↗
PubMed1999

T-channel-selective calcium channel blockade: a promising therapeutic possibility, only preliminarily tested so far: a review of published data. T-Channel Calcium Channel Blocker Study Group.

Basic studies as well as short-term clinical trials of the T-channel-selective calcium channel blocker, mibefradil, are reviewed. The compound reduced afterload and was effective for the symptomatic treatment of hypertension and stable angina pectoris. It did not display any relevant negative inotropic or positive chronotropic effect. Mibefradil has been withdrawn by the manufacturer because of drug interaction at the cytochrome P-450 3A4 enzyme. It is hoped that new T-channel-selective calcium channel blockers will be developed to explore further this promising but so far only preliminarily tested therapeutic possibility.

Angina Pectoris↗
PubMed1997

Comparison of echocardiography with magnetic resonance imaging in the assessment of the athlete's heart.

AIM: The purpose of the study was to compare the accuracy of M-mode echocardiography and two different two-dimensional echocardiographic approaches in the assessment of left ventricular mass and volumes in endurance-trained and strength-trained athletes, using magnetic resonance imaging as reference standard. METHODS AND RESULTS: We studied 19 athletes and 10 untrained control subjects, M-mode and two-dimensional echocardiography were compared to magnetic resonance imaging. M-mode echocardiographic left ventricular mass was calculated using the Penn cube convention. Two-dimensional echocardiographic left ventricular mass was calculated using (1) the area-length method as proposed by the American Society of Echocardiography (ASE) and (2) as proposed by Reichek. The best correlation between magnetic resonance imaging and echocardiographic left ventricular mass and volumes was observed with the ASE two-dimensional echocardiographic method. The agreement between them (-3.4 +/- 7.6 g and 18.5 +/- 19.5 ml) was better than between Reichek two-dimensional echocardiography and magnetic resonance imaging (-39.4 +/- 15.4-g and 52.8 +/- 21.7 ml), and demonstrated less random difference than M-mode echocardiography and magnetic resonance imaging (3.2 +/- 21.1 g resp. 15.1 +/- 30.0 ml). CONCLUSION: We conclude that the ASE two-dimensional echocardiographic approach, when using magnetic resonance imaging as a reference standard, was the most accurate estimator of left ventricular mass and volumes in both controls and athletes.

Adult↗
PubMed1996

Cardiac anatomy, function and metabolism in elite cyclists assessed by magnetic resonance imaging and spectroscopy.

We investigated whether left ventricular hypertrophy in elite cyclists is associated with functional changes or abnormal energy metabolism. Left ventricular hypertrophy is a powerful risk factor for sudden cardiac death with different prognostic significance among the various geometric forms. Cyclists may have a combination of mixed eccentric and concentric hypertrophy. Magnetic resonance imaging was used to define left ventricular mass, geometry and function. Thirteen highly trained male cyclists and 12 healthy controls were investigated. Proton-decoupled phosphorus-31 cardiac spectroscopy was performed to assess parameters of myocardial high-energy phosphate metabolism. Left ventricular mass and end-diastolic volumes normalized for body surface area were significantly higher in cyclists (124.1 +/- 9.4 g.m-2 and 106.2 +/- 11.4 ml.m-2, respectively) than in controls (85.9 +/- 9.3 g.m-2 and 79.1 +/- 11.6 ml.m-2, respectively), (both P < 0.0001). The left ventricular mass to end-diastolic volume ratio, as a parameter of left ventricular geometry, was not significantly increased in cyclists compared to controls. Resting left ventricular ejection fraction, cardiac index, and systolic wall stress in cyclists did not differ significantly from those of controls. The phosphocreatine to adenosine triphosphate ratio was not significantly different between cyclists and controls (2.2 +/- 0.34 vs 2.2 +/- 0.17, ns). Cyclists show prominent left ventricular hypertrophy with normal geometry. The finding that the hypertrophic hearts of the cyclists had normal left ventricular function and a normal phosphocreatine to adenosine triphosphate ratio suggests that sport-induced left ventricular hypertrophy is a physiological adaptation rather than a pathophysiological response.

Adenosine Triphosphate↗
PubMed1995

Reproducibility of MRI-derived measurements of right ventricular volumes and myocardial mass.

Magnetic resonance (MR) imaging has been shown to provide accurate measurements of right ventricular (RV) volumes and myocardial mass. The purpose of this study was to evaluate the reproducibility of MR imaging, which in clinical practice may be as important as its absolute accuracy. The reproducibility of MR imaging measurements of the right ventricle was assessed by analyzing 40 serial functional MR imaging examinations of the right ventricle with variance component analysis. Standard deviations and 95% ranges for change were: for RV myocardial mass, 5.9 and 16 g; and for RV ejection fraction, 6.0% and 16%, respectively. Reproducibility was similar for cine and spin-echo MR imaging. The intraobserver and interobserver errors were especially large, indicating that observer subjectivity is the limiting factor in the interpretation of the MR images. This study suggests that the reproducibility of RV measurements is adequate to detect RV hypertrophy and a low ejection fraction in the individual patient. For accurate follow-up examinations, whereby smaller changes are to be detected, the reproducibility of MR imaging measurements may not be sufficient. More effort is needed to improve the reproducibility of MR imaging measurements.

Adult↗
PubMed1994

Evaluation of cardiac function with magnetic resonance imaging.

A large body of evidence has accumulated to substantiate the accuracy of functional MR measurements of both ventricles. Because of good accuracy and superior reproducibility, MR imaging may be considered the gold standard for in vivo quantification of left and right ventricular ejection fraction, myocardial mass, and wall stress. New prospects for functional MR imaging include determination of the end-systolic volume-pressure relation as an index of myocardial contractility. The ability of MR imaging to detect wall motion disturbances may be enhanced further by combining myocardial tagging techniques with finite element analysis. Conventional MR imaging is limited by long examination times, but recent ultrafast modifications of echo-planar imaging allow completion of a functional heart study within seconds. Implementation of ultrafast MR imaging will greatly increase the usefulness of MR imaging for routine evaluation of cardiac function.

Cardiac Volume↗
PubMed1994

Head-to-head comparison between technetium-99m-sestamibi and thallium-201 tomographic imaging for the detection of coronary artery disease using combined dipyridamole-exercise stress.

AIM: The purpose of this study was a head-to-head comparison of tomographic imaging (SPECT) with technetium-99m (Tc-99m)-sestamibi and thallium-201 (Tl-201) using dipyridamole-low-level bicycle exercise stress for the assessment of coronary artery disease. METHODS: We studied 38 consecutive patients referred for the evaluation of chest pain who had undergone coronary angiography. The patients were randomly allocated to Tc-99m-sestamibi SPECT followed by Tl-201 SPECT or vice versa. The accuracy of both tracers in detecting significant coronary artery disease (> 50% luminal stenosis) was 87% (95% confidence interval 72-96%). Only two patients were classified differently by the two methods. RESULTS: On a segmental basis, good agreement was found between Tc-99m-sestamibi and Tl-201 for both the localization and the nature of perfusion defects (reversible or persistent) identified (Cohen's kappa = 0.67). CONCLUSION: No clinically relevant differences in diagnostic accuracy were demonstrated between Tc-99m-sestamibi and Tl-201 SPECT using combined dipyridamole-exercise stress for the evaluation of coronary artery disease.

Aged↗
PubMed1992

Silent myocardial ischemia after acute myocardial infarction.

Silent ischemia after myocardial infarction has definite prognostic significance but should be interpreted within the context of other prognostic indicators. The rationale for therapeutic intervention is based on the prognostic implications of silent ischemia and the potentially deleterious effect of repeated episodes of ischemia on the integrity of the left ventricle. We measured parameters of ischemia in 20 patients who showed asymptomatic ischemic ST-T changes on exercise testing in the early phase after myocardial infarction. After diltiazem administration, a reduction of exercise-induced ST-T depression from 2.3 +/- 0.8 to 0.7 +/- 0.6 mm (p less than 0.01) occurred, and regional wall-motion score at exercise, determined by radionuclide angiography, improved significantly (p less than 0.02). These and other observations warrant further studies in which the duration, severity and frequency of the ischemic episodes should be quantified and correlated with prognosis after myocardial infarction.

Coronary Disease↗
PubMed1992

Assessment of acute myocardial infarction by nuclear imaging techniques.

In recent years, nuclear cardiology techniques have been successfully applied in patients with acute myocardial infarction. These scintigraphic measurements have provided important diagnostic, therapeutic, and prognostic information based on the extent of myocardial damage and the functional reserve of the left ventricle. In particular, in the thrombolytic era, myocardial perfusion imaging and radionuclide angiography have been shown to be valuable methods for studying the effects of reperfusion on the extent of myocardial damage. Nuclear magnetic resonance imaging, preferably with contrast enhancement, is one of the newly developed nuclear imaging techniques that have probably the greatest potential in accurately delineating myocardial infarct size and in evaluating left ventricular function. Radionuclide procedures, on the other hand, employ more biologically oriented tracers and are therefore capable of monitoring biochemical changes in the course of acute myocardial infarction.

Antibodies, Monoclonal↗
PubMed1991

Right ventricle wall motion abnormalities in patients treated with chemotherapy.

Doxorubicin is a cytotoxic agent used in the treatment of patients with various malignancies. Its clinical value is limited by a dose-related cardiotoxicity. Wall motion was analyzed in 52 patients during different stages of treatment. Eleven patients were studied once, and in 41 patients serial radionuclide ventriculography was performed from 2 to 5 times. Abnormal wall motion was found in 96 out of 1,062 segments (9.0%), of which 33 out of 735 (4.5%) were in the left ventricle (LV) and 65 out of 327 (19.9%) were in the right ventricle (RV). The number of abnormalities in the RV was significantly higher than in the LV (P less than 0.001). Regional analysis of LV and RV in 109 40 degrees LAO studies and in 102 75 degrees LAO studies showed abnormal wall motion in the following segments: LV--posterobasal 6 (5.9%), inferior 2 (2.0%), anterior 5 (4.9%), anteroseptal 11 (10.1%), apical 5 (4.6%), posterolateral 4 (3.7%); RV--septal 44 (40.4%), apex 15 (13.8%), and the free wall 6 (5.5%). The left ventricular ejection fraction decreased from 74% median (M) in baseline studies to 54% (M) in the highest dose group (greater than 650 mg/m2). The present data show an increased number of wall motion abnormalities in the RV compared with the LV, particularly in the RV septum (P less than 0.001).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

99Tcm-SESTAMIBI for planar myocardial perfusion imaging; not as ideal as the physical properties.

99Tcm-methoxyisobutyl isonitrile (Tc-SESTAMIBI) has recently been introduced as a new myocardial perfusion agent which exhibits ideal physical properties for imaging with the gamma camera. To assess the diagnostic accuracy of planar Tc-SESTAMIBI, myocardial perfusion imaging was performed in 60 consecutive patients at rest and during exercise. The results were compared with coronary angiographic findings, obtained within 3 months of the exercise test. Planar 201Tl images were also performed on the same day and to the same level of stress as the Tc-SESTAMIBI exercise. Exact segmental agreement between Tc-SESTAMIBI and 201Tl was 77%. Nineteen per cent of all 900 segments demonstrated ischaemia with Tc-SESTAMIBI and 20% with 201Tl. The overall sensitivity for detecting haemodynamically significant coronary artery disease with Tc-SESTAMIBI was 86% and specificity was 78%; with 201Tl the values were 89 and 78%, respectively (differences not significant). Vessel-specific comparative detection rates revealed no statistical significant differences between both radiopharmaceuticals. Intra-observer variability for Tc-SESTAMIBI images was 12% and for 201Tl it was 14%. Inter-observer variability for Tc-SESTAMIBI was 14% and for 201Tl 17%. Although the physical characteristics of Tc-SESTAMIBI allow crisp and clear high-count density imaging, no significant differences are found when planar images are compared with 201Tl and are well within observer variabilities.

Adult↗
PubMed1991

Discordance of visual and quantitative analysis regarding false negative and false positive test results in thallium-201 myocardial perfusion scintigraphy.

Visual assessment and quantitative analysis of exercise thallium-201 myocardial perfusion scintigraphy was performed in 203 consecutive patients who underwent coronary arteriographic studies to identify the factors associated with false negative and false positive studies. Also the discordance between visual and quantitative analysis was evaluated. One hundred sixty-two (80%) of these 203 patients had significant coronary artery disease (CAD), i.e. a luminal stenosis greater than or equal to 50%. Fifty-two (32%) of these 162 patients with documented CAD showed negative thallium results either by visual or quantitative analysis. When interpreted visually 36/162 (22%) of patients were judged as negative, and when analyzed quantitatively 41/162 (25%) of patients were judged as negative (ns). Of the total group of 52 patients with false negative visual and/or quantitative analysis test results, 27 (17%) showed discordance between these two methods. Of the 41 patients without significant CAD, 12 (29%) showed positive thallium findings. Visual interpretation was positive in 9/41 (22%) of patients without significant CAD, and quantitative analysis in 5/41 (12%) (ns). Of the total group of 12 patients with positive visual and/or quantitative analysis test results, 10 (24%) showed discordance between these two methods. Therefore, in the total group, 37 patients (18%) showed discordance between visual and quantitative analysis. It is concluded that 1) the sensitivity and the specificity of visual interpretation and quantitative analysis of thallium-201 exercise scintigraphy for detecting CAD is similar, and 2) that there is frequent discordance of visual interpretation and quantitative analysis in thallium-201 exercise scintigraphy.

Coronary Disease↗