Usefulness of coronary angiography for assessing left ventricular function
Abstract: This thesis focus on the physiological information, on left ventricular (LV) motion in the long axis, evaluated in routine coronaty angiography sequences and based on previous knowledge from echocardiographic studies. As coronary angiography has become a very frequent examination, a method for assessment of LV function from routine coronary angiograms would probably have a significant impact on clinical work. Therefore, the motion of the left coronary artery is analysed in the studies described below.In a pilot study of 84 patients, refetTed for coronaty and LV angiography, the systolic descent of the left coronary ostium (LCO) towards apex was measured. This simple manual measure from routine coronary angiograms showed a mean amplitude of 9.6 mm (range 3.0-15.0) and significant linear correlation to ejection fraction (EF) (r = 0.72, SEE = 10.1, p < 0.001).In the second study, including 28 patients, coronary angiography and echoeardiography was used for measurement of circumflex artery motion (CAM) and mitral annulus motion (MAM) respectively. CAM amplitude tended to be higher than MAM in the higher range of amplitudes while the opposite was found in the lower range of amplitudes.In a eehocardiographic study of another 26 patients; it was found in 13 patients with normal EF that the motion amplitude of a site epicardially at the most basal lateral patt of the LV wall was significantly (p < 0.001) higher than endoeardially, but in 13 patients with decreased EF (< 50%) there was no significant difference between the two sites. The motion amplitude epicardially corresponds to the motion amplitude of the circumflex artery.In the 13 patients with normal EF the motion amplitude of the closed mitral valves was significantly lower than the motion amplitude epi- and endocardially during systole, with a rather conic shape of the atrioventricular plane (AVP) at the onset of systole. In end-systole the different parts of the left AVP, the epicardial part (circumflex artery), the endocardial part (mitral annulus) and the valves were almost on the same level.In the third study, including 73 patients referred for coronary and LV angiography, the systolic descent of LCO and of the circumflex artery towards apex was measured manually. The mean motion amplitude of LCO (9.1 mm, range 1.7-19.7) was significantly (p < 0.001) lower than the mean motion amplitude of CAM measured from the proximal part of the artery (14.3mm, range 3.0-25.0) or from the distal part of the artery (14.4 mm, range 1.2-26.6). There was no significant difference between the amplitudes at these two sites of the circumflex artery.It was found that the ratio between CAM and the end-diastolic length of the ventricle, which can be denominated fractional shortening in the long axis (FSL), was a better index of LV systolic function than CAM amplitude per se. There was a significant linear correlation between EF obtained by LV angiography and FSL (r = 0.81, SEE = 8.2, p < 0.001).A power regression model had the best correlation between EF and FSL. In this model the correlation between EF and FSL can be described by the equation EF(%) = 19.2 x FSL(%)0.45 (R = 0.86, SEE = 0.14, p < 0.001). When values of FSL ≥ 10% were selected to define a normal EF (≥ 50%) there was a sensitivity of 95% and a specificity of 93%.Visual estimation of EF from assessment of CAM was not as good as the use of calculated FSL but may be useful as fast screening method when classifying normal or impaired LV function.In the fourth study, including 72 patients from the previous third study, who were referred for coronary and LV angiography, the systolic and diastolic parameters of CAM were measured by M-mode from coronary angiography. There were no significant difference between M-mode measures of CAM amplitude and calculated FSL compared to the manually measured CAM amplitude and calculated FSL.The mean maximal systolic velocity of CAM was 70.1 mm/s (SD 21.8, range 17.6-139.0). When values ≥ 54 mm/s, a limit previously reported from an echocardiographic study (tissue Doppler of MAM), were selected to define a normal EF (≥ 50%) the sensitivity was 84.6% and specificity 94.6%.A subgroup of 23 patients (17 had EF ≥ 50%) were examined by echocardiographic M-mode of MAM, within 24 h before the angiographic examination, for comparison of amplitudes and velocities measured by angiographic M-mode of CAM.The total amplitude of CAM was significantly higher (p < 0.001) higher than the amplitude of MAM and so was the amplitude due to atrial contraction (p < 0.001).The maximal systolic velocity of CAM was significantly (p < 0.001) higher than the corresponding velocity of MAM. The early maximal diastolic velocity of CAM was also significantly higher (p < 0.05) than the corresponding velocity of MAM. There was no significant difference between the late maximal diastolic velocity of CAM and the late diastolic velocity of MAM.In summary, the systolic and diastolic phases of CAM, and thereby also the systolic and diastolic LV function, are well monitored by the angiographic M-mode method. The systolic indices arc CAM amplitude, FSL and maximal systolic velocity of CAM. The diastolic indices are maximal early diastolic velocity of CAM and the amplitude due to atrial contraction.The amplitudes and velocities of CAM are higher than the corresponding values for MAM in patients with normal EF. Therefore it is obvious that reference values of MAM and CAM amplitudes and velocities cannot be used interchangeably.
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