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Atrio-ventricular valve plane (AV-plane) displacement and left and right ventricular contour variation during the cardiac cycle, were determined by coronary cineangiography. Six patients suffering from coronary artery heart disease was examined.
Coronary cineangiography (CA) is used as a routine method for the detection of atheromatosis of the coronary arteries.
In our study of six patients examined due to anginal pain (functional group II to III) and because they were all candidates for a coronary by-pass operation, none showed symptoms of heart failure.
| Patient no. | |
| 1 | should manifest symptoms of both angina and a slight mitral valve insufficiency. |
| 2 | showed hypokinesia in the apex area together with an isolated stenosis in the left anterior descending branch of the left coronary artery |
| 3, 6 | had anginal pain. |
| 4 | had healthy coronary arteries, but a very short circumflex artery which hampered registration on the left side. |
| 5 | had had an infarction more than one year before the examination. |
The angiographic reproduction of the left and right coronary arteries, was used to trace the movement of the AV-plane during the cardiac cycle.
The percutaneous femoral approach according to Judkins was used. Cine-images, 30 per second, were recorded on 35 mm film. Two right anterior oblique projections (no tilt crano-caudally) of the left and the right coronary arteries were performed in each patient. The degree of enlargement was adjusted to allow reproduction of the entire heart. Routine doses of contrast fluid were given. Exposure took place at end-expiratory apnea. Angle of projection and distances, are the same for left and right side registration.
One frame in each pair of images was analysed using standard projection equipment, by drawing the atrial contour of the arteries in the atrio-ventricular groove (Fig. 4-1A,Fig. 4-1B). Ossified structures of the spine were used as points of reference. The outer contour of the heart was also drawn. Because of the very slight changes in this contour, only end-systolic and end-diastolic images are shown.
Lines of reference (Lrf, dashed) (Fig. 4-1A,Fig. 4-1B) were drawn through points in the coronary artery walls, enabling measurement of the movement of the valve plane edge at different positions. The points were selected with respect to ease of identification e.g., at branchings or discontinuities. Two central lines (C) were defined:
Directions of lines C were set in accordance with the respective left and right dotted lines of reference adjacent to them. Then distances thus defined were bisected by lines A and B at LV and RV.
At the point of intersection of the valve plane in its extreme diastolic position (after atrial systole) and line C, distances dLV and dRV to apex were determined. They defined the maximal length of the ventricle and were used as reference.
In most cases there was no change in the position of apex relative to reference points in the spine.
Points of intersection of the valve plane with lines A and B, were used to characterise valve plane movement. The distances travelled were measured and calculated as a percentage of the reference distance (dLV, dRV).
Valve plane movement was further visualised in points of intersections for A and B, by plotting their variation against time (Fig. 4-2A, Fig. 4-2B).
The mean value of distances travelled by the valve plane in lines A and B (aLV, bLV, aRV, bRV) are given in Table Xa.
Variation of heart outer contour laterally and medially is given in Table Xb.
Observation of valve plane movement by CA, is based on its close morphologic association with the main right coronary artery and the circumflex branch of the left coronary artery. The main stem of the right coronary artery originates from the right sinus of Valsalva, and follows the atrio-ventricular groove. The left circumflex artery leaves the left main coronary artery, and runs in the atrio-ventricular groove in the opposite direction. The arteries are kept in place by adipose and connective tissue, which is in turn connected to the anulus fibrosus (. Fig. 3-7A-B, Fig. 3-8A-B). They may be assumed to move in close association with the valve plane. Their contrast filling is usually excellent.
Valve plane displacement, calculated as a percentage of the reference distance (dLV, dRV) in intersection of A and B (Table Xa), is affected by projection errors and possibly also by different forms of heart diseases.
Patient no. 6 was not considered when calculating the average of the LV values, because of conspicuous deviation from the rest of the group.
In an oblique projection of the long heart axis, distortion will result in reduced valve plane movement (cf. Fig. 5-9). The motion (bRV) of the atrio-ventricular plane on the right side, along line B, can be overestimated. That may be due to the form of attachment of RV at the anulus fibrosus, and the intimate attachment of the right coronary artery to RV (. Fig. 3-7A-B, Fig. 3-8A-B).
Considering the errors of the method, the displacement of the left side AV-plane (which is about 16 % of the reference distance dLV) should be regarded as an underestimated value. Especially magnification and projection errors (Fig. 5-8) and possible effects of heart disease should be considered.
The displacement of the AV-plane at the right side is considerably higher (approximately 21 %) of the reference distance dRV. Whether this value is over- or underestimated is hard to tell, due to the topographic anatomy of right coronary artery (Fig. 3-8A-B).
The effect of atrial systole (Fig. 4-2A,Fig. 4-2B) on the valve plane displacement, was evident in two patients (no. 2 and 5).
The mean value of variation in outer contour is calculated for each patient where variation is at a maximum. Values for laterally-anteriorly LV and medially-diaphragmally RV are given in Table Xb. Variation is expressed as a percentage of the reference distance dLV and dRV.
The recorded movement is the result of tangential beams in both positions. Tangential beams are, however, not parallel. Therefore the contour recorded is an enlarged one. Outer contour variation may therefore be correct, too large, or too small, depending on the positioning of the major heart axis relative to the X-ray source and detector.
In Fig. 5-9 30o oblique long axis projection is shown. This axis will appear longer then it actually is. Outer contour movement related to axis length will therefore be underestimated.
The opposite is true for a 45o oblique projection (Fig. 5-9) giving a reduced axis length.
The studies show that wall motion is greatest near the AV-plane, and that it is the medially and diaphragmatically situated contour that has the greatest variation (cf. [174]).
Movements laterally and medially almost cease near the apex.
Results laterally for patient no. 2 were omitted from Table Xb, due to an inverse movement of about 1.5 mm. The diseases of the other patients did not visibly affect outer contour variation.
If the length of the major heart axis is assumed to be 90 mm, variation of outer ventricular contour is between 1 and 2 mm.
By comparing the maximum diastolic image (atrial systole included) with the minimum systolic image, the mean value of the outer contour variation of left and right ventricle obtained. By using coronary cineangiography (in right oblique position), the mean value of the outer contour variation was found to be between 1 and 2 mm at the AV-plane. It was practically reduced to zero at apex.
In the same investigation it was found that the motion of the AV-plane was about 16 mm on the left side, and 21 mm on the right side. At least the value from the left side is underestimated, due to projection errors and underlying heart disease of the investigated group.
| Copyright © 1999 Inovacor AB. |
