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  • 1
    Electronic Resource
    Electronic Resource
    Noncontact Mapping of Ventricular Tachycardia in a Closed-Chest Animal Model of Chronic Myocardial Infarction (2003)
    350 Main Street , Malden , MA 02148-5018 , U.S.A . : Blackwell Publishing
    Pacing and clinical electrophysiology 26 (2003), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Treatment of ventricular tachyarrhythmias in the setting of chronic myocardial infarction requires accurate characterization of the arrhythmia substrate. New mapping technologies have been developed that facilitate identification and ablation of critical areas even in rapid, hemodynamically unstable ventricular tachycardia. A noncontact mapping system was used to analyze induced ventricular tachycardia in a closed-chest sheep model of chronic myocardial infarction. Twelve sheep were studied 96 ± 10 days after experimental myocardial infarction. During programmed stimulation, 15 different ventricular tachycardias were induced in nine animals. Induced ventricular tachycardia had a mean cycle length of 190 ± 30 ms. In 12 ventricular tachycardias, earliest endocardial activity was recorded from virtual electrodes, preceding the surface QRS onset by 30 ± 7 ms. Noncontact mapping identified diastolic activity in ten ventricular tachycardias. Diastolic potentials were recorded over a variable zone, spanning more than 30 mm. Timing of diastolic potentials varied from early to late diastole and could be traced back to the endocardial exit site. Entrainment with overdrive pacing was attempted in nine ventricular tachycardias, with concealed entrainment observed in seven. Abnormal endocardium in the area of chronic myocardial infarction identified by unipolar peak voltage mapping was confirmed by magnetic resonance imaging. These data suggest that induced ventricular tachycardia in the late phase of myocardial infarction in the sheep model is due to macroreentry involving the infarct borderzone. The combination of this animal model with noncontact mapping technology will allow testing of new strategies to cure and prevent ventricular tachycardia in the setting of chronic myocardial infarction. (PACE 2003; 26:2253–2263)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.2003.00356.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electrocardiographic Characteristics in Patients with Nonrheumatic Atrial Fibrillation and Their Relation to Echocardiographic Parameters (2001)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: BOLLMANN, A., et al.: Electrocardiographic Characteristics in Patients with Nonrheumatic Atrial Fibrillation and their Relation to Echocardiographic Parameters. The aim of this study was to determine the relation between (1) ECG fibrillatory wave amplitude and left atrial diameter and left atrial appendage (LAA) flow velocity using different ECG recording techniques, and (2) ECG fibrillatory frequency and frequency of LAA contractions in patients with nonrheumatic AF. In 36 patients (22 men, 14 women, mean age 61 ± 11 years) with persistent AF, ECG recordings were performed using a standard 12-lead ECG and an orthogonal ECG lead system using a high gain, high resolution ECG. AF was classified as coarse (fibrillatory amplitude ≥ 1 mm) or fine (fibrillatory amplitude 〈 1 mm) in leads I, aVF, V1 and corresponding leads X, Y, and Z. Fibrillatory frequency from the ECG was determined by subtracting averaged QRST complexes and applying a Fourier analysis to the resulting signal. Doppler flow was obtained from LAA during transesophageal echocardiography and LAA emptying velocity was determined. Fourier analysis was also applied to the Doppler signal generating the frequency of LAA contractions. Coarse AF was observed in 0, 9, and 18 patients in leads I, aVF, and V, respectively. It was more often (P 〈 0.05) detected in corresponding leads X (n = 13), Y (n = 31), and Z (n = 23). Fine AF in lead X was associated with a reduced LAA velocity (33 ± 16 cm/s in coarse AF vs 22 ± 13 cm/s in fine AF, P = 0.05). There was neither a relation between AF coarseness in any other ECG lead and LAA flow velocity, left atrial diameter, or echo contrast. In 25 patients with an active LAA flow, the mean frequency of LAA contractions was 6.8 ± 0.8 Hz. The corresponding mean frequency obtained from the ECG was 6.7 ± 0.7 Hz (r = 0.85, P 〈 0.001). The mean difference between these two measures was 0.04 Hz, and the 95% confidence limits were 0.90 and – 0.82 Hz using the Bland-Altman method. In conclusion, AF coarseness and its relation to LAA flow velocity depend on the ECG recording technique used. LAA contractions represent one mechanical correlate of the electrical fibrillatory activity in AF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.01507.x
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  • 3
    Electronic Resource
    Electronic Resource
    Quantification of Right and Left Ventricular Function by Cardiovascular Magnetic Resonance (2000)
    Springer
    Herz 25 (2000), S. 392-399 
    Details
    ISSN: 1615-6692
    Keywords: Key Words Cardiac imaging ; MRI ; Heart ; Ventricular function ; Schlüsselwörter Kardiale Bildgebung ; Magnetresonanztomographie ; Herz ; Ventrikelfunktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die kardiale Dysfunktion ist eine der Hauptursachen kardiovaskulärer Morbidität und Mortalität. Eine genaue und reproduzierbare Bestimmung der Herzfunktion ist essentiell für die Diagnosestellung, Prognoseabschätzung und Beurteilung des Therapieeffekts beim einzelnen Patienten. Die kardiovaskuläre Magnetresonanztomographie (CMR) bietet eine Messmethode für die globale und regionale Herzfunktion, die nicht nur genau und reproduzierbar, sondern auch nichtinvasiv, ohne ionisierende Strahlung und unabhängig von geometrischen Annahmen und einem akustischen Fenster ist, das den Einsatz der Echokardiographie limitiert. Mit der Verfügbarkeit schnellerer MR-Scanner und automatisierter Analysesysteme sowie mit zunehmender Verbreitung und reduzierten Kosten wird CMR bald den Referenzstandard für die Messung der Herzfunktion darstellen.
    Notes: Abstract Cardiac dysfunction is a major cause of cardiovascular morbidity and mortality. Accurate and reproducible assessment of cardiac function is essential for the diagnosis, the assessment of prognosis and evaluation of a patient's response to therapy. Cardiovascular Magnetic Resonance (CMR) provides a measure of global and regional function that is not only accurate and reproducible but is noninvasive, free of ionising radiation, and independent of the geometric assumptions and acoustic windows that limit echocardiography. With the advent of faster scanners, automated analysis, increasing availability and reducing costs, CMR is fast becoming a clinically tenable reference standard for the measurement of cardiac function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000590050031
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