| ObjectiveTo find a proper way for creation of chronic left ventricular aneurysm in rabbit.Materials and methods1. Thirty five rabbits were used for model establishment. Acute myocardial infarction (AMI) was created by concomitantly ligation of left anterior descending (LAD) coronary artery and circumflex (Cx) branch at the middle point after ischemia preconditioning for the purpose of prevention of arrhythmia.2. Before and immediately after coronary artery ligation, left ventricular systolic pressure (LVESP) and diastolic pressure (LVEDP) was measured by a 20 gauge tube directly inserted into the ventricular chamber via the apex.3. Transthoracic echocardiography was used to measure the dimension of the ventricular chamber, interventricular septum (IVS), left ventricular posterior wall (LVPW), left ventricular end diastolic volume (LVEDV) and systolic volume (LVESV), and ejection fraction (EF) from the view of long axis. Aneurysm was confirmed and its percentage to left ventricle was calculated.4. Four weeks after myocardial infarction, rabbits with prominent ventricular aneurysm confirmed by echo were selected for ventriculagram.5. Hearts of normal rabbit and the one with aneurysm were excised to directly investigate the ventricular aneurysm and its area6. Agar intra-chamber irrigation was used to study left ventricular geometric structure in normal heart and the one with aneurysm.7. Specimens of normal rabbit and the one with aneurysm were collected for pathologic examination.Results1. Thirty one (88.6%) rabbits survived the myocardial infarction. Aneurysm model was successfully created in 26 rabbit (83.9%).2. Echocardiography results: (1) Echo showed that aneurysm, acting as bulge and akinesis or dyskinesis, involved apex and the anterior and lateral wall of LV. Mean area of aneurysm was 33.4±2.4% (range 30.3% -36.7% ) . (2) After aneurysm formation, the length of ventricular chamber from apex to the middle point of mitral valve, IVS, LVEDV, and LVESV were significantly increased compared with pre-infarction data. However, EF was significantly decreased.3. After ligation of coronary artery, LVESP was significantly decreased but elevated one month later. LVEDP was significantly increased immediately after ligation and progressively deteriorated one month later.4. Investigation of the excised heart showed that aneurysm involved the apex and anterior and lateral wall of LV, but IVS was not involved, which was similar to the echo results.5. Agar intra-chamber irrigation showed that bulge of LV wall was prominent in the area of aneurysm.6. Ventriculogram also showed the prominent bulge of the aneurysm and its akinesis of dyskinesis.7. Myocyte degeneration was demonstrated in pathologic examination.Conclusion1. Ligation of LAD and Cx at the middle point can produce LV aneurysm withmean area of 33.4±2.4%.2. Aneurysm involves the apex and anterior and lateral wall of LV but IVS is intact, which suggests that it is possible to eliminate the aneurysm without cardiopulmonary bypass in experimental study.3. Agar intra-chamber irrigation can be used to directly show the geometric structure of LV.Part II Comparison study of two procedures to reconstruct left ventricleObjectiveTo compare purse reconstruction and linear repair the early results of the two procedures.Materials and methods1. Twenty four rabbits with LVA were included in this study and each 12 ones were respectively divided into purse reconstruction group and linear repair group.2. Procedure introduction: (1) Purse reconstruction: The adjacent between the contractile myocardium and aneurysm was firstly confirmed. 3/0 prolene suture was placed right at the adjacent for purse reconstruction. After knotting, the aneurysm was eliminated. (2) linear repair: After the adjacent was investigated, 3/0 prolene suture with plegets was placed parallel to LAD at the adjacent in a fashion of Cooley's linear repair to eliminate the aneurysm.3. Before and immediately after operation, LVESP and LVEDP were measured. Two weeks later, pressure data was collected again via right carotid artery.4. Two weeks after operation, echo examination was repeated to investigate the LV dimension and volume like the first part of the study. Agar intra-chamberirrigation and heart anatomy were also repeated to show the geometric structure of LV after aneurysm surgery.Results1. Twenty three (87.5%) rabbits survived the operation. Three rabbits died of acute heart failure or ventricular fibrillation.2. Echocardiography results: (1) In both groups, aneurysm was eliminated and the dimension, LVEDV, LVESV were decreased after operation, but EF was significantly increased. The LVESV of purse group was lower than that of linear repair group and EF of purse group was higher than that of linear repair group with statistical significance.3. In both groups, LVESP increased but LVEDP decreased significantly. However, LVEDP of purse reconstruction group was lower than that of linear repair group with statistical significance.4. Heart anatomy showed that aneurysm was nearly eliminated in both groups. The myocardium direction relined to approximately normal after purse reconstruction but not after linear repair.5. Agar intra-chamber irrigation showed that after elimination of aneurysm, geometric structure of purse reconstruction group was much better than that of linear repair group.ConclusionBoth purse reconstruction and linear repair can improve LV function and the former one is better than latter one in surgical intervention for aneurysm of meanarea 33.4±2.4%.
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