Annular Motion : Assessment of Cardiac Function using Echocardiography and Magnetic Resonance Imaging
Abstract: This thesis concentrates on the assessment of cardiac function, both systolic and diastolic using variables originating from the longitudinal motion of the heart using both established and novel non-invasive imaging techniques. We developed a new magnetic resonance imaging (MRI) technique that creates an M-mode MRI image, analogous to the one used in echocardiography and enables quantitative assessment of cardiac motion. The MRI M-mode method was compared with M-mode echocardiography in a phantom study, by measuring mitral and tricuspid annular motion in 20 normal subjects, and in a study of right ventricular function in 17 patients after coronary artery bypass surgery. The agreement between M-mode MRI and Mmode echocardiography was good. However, the amplitudes were somewhat higher measured by MRI, probably because of less angle error in the MRI calculation, furthermore the lower resolution in the MRI image may have contributed.Pulsed tissue Doppler, a recently developed Doppler modality that gives the possibility of recording instantaneous annular /or myocardial velocities on-line, was used to obtain reference values of mitral and tricuspid annular motion in 27 normal subjects of different ages. Diastolic left ventricular function was assessed in 15 patients with systemic hypertension and in 10 patients with moderate to severe aortic stenosis. Furthermore, pulsed tissue Doppler was used in the evaluation of right and left ventricular function in 15 patients with arrhythmogenic right ventricular cardiomyopathy (ARVC).The mitral and tricuspid annular velocity pattern in normal subjects is characterised by three major components: asystolic (SA) velocity, an early (EA) diastolic velocity, and a late (AA) diastolic velocity. In normal young subjects, the EA-peak velocity was highest; with increasing age, the EA-peak velocity decreases and the AA-peak velocity increases, with similar changes in both the mitral and tricuspid annular velocity pattern. In patients with left ventricular hypertrophy the EA/AA-ratio was significantly decreased compared with age- match normal subjects. Comparing ARVC patients with normal subjects the tricuspid annular EA-peak velocity was significantly decreased as well as the lateral SA-peak velocity. Our result indicates that abnormal diastolic tricuspid annular velocity pattern may be an early sign of right ventricular myocardial dysfunction in patients with ARVC. The septal mitral annular SA-peak velocity was significantly decreased in ARVC patients compared to the controls. This in accordance with subjective analysis of echocardiographic wall motion and T1-201 SPECT that showed left ventricular abnormalities in 93% of the patients predominantly located in the anteroseptal and posteroseptal segments.
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