摘要
第一部分兔慢性室壁瘤模型的建立
目的
探索建立兔慢性室壁瘤模型的方法。
实验方法
1．取成年新西兰大白兔35只，结扎冠状动脉前降支和回旋支中段，结扎前缺血预调两次，每次各3分钟，造成急性心肌梗死模型。
2．结扎前和结扎后当时经心尖部测左心室收缩压和舒张压。
3．结扎术前、1周、4周后行超声心动图检查，测量左心室前后径、长径、左室舒张末和收缩末期容积、射血分数，并计算室壁瘤所占左心室面积。
4．4周后选择室壁瘤兔行左心室造影。
5．取室壁瘤兔行左心室长轴和短轴解剖心脏，留大体病理标本。
6．取正常兔和室壁瘤兔用琼脂做左心室腔内铸型，并测量铸型体容积。
7．取正常兔和室壁瘤兔心肌标本行组织病理学检查。
8．采用超声心动图、大体标本病理解剖和左心室腔内铸型等证实是否形成解剖性室壁瘤。
结果
1．实验兔共35只，31只存活，存活率88.6％。建成室壁瘤模型26只，成功率为83.9％。
2．超声心动图结果：(1)室壁瘤累及心尖部和左室前侧壁，局部膨出，运动消失或呈反常运动。室壁瘤面积为33.4±2.4％(范围：30.3％-36.7％)。(2)形成室壁瘤后，左室前后径有增加趋势，但无显著性差异；左室长径显著性增加；室间隔厚度显著增加；左室后壁厚度有增加趋势，但无显著性差异；左室舒张末期和收缩末期容积均显著性增加；左室射血分数显著性降低。
3．血流动力学结果：(1)结扎冠状动脉后，左室收缩压显著性升高，1个月以后，虽有所回升，但仍显著性低于正常。(2)结扎冠状动脉后，左室舒张末期压力进行性升高。
4．大体病理标本形态观察室壁瘤累及左室心尖部和前侧壁，室间隔未受累。
5．左心室腔内铸型见室壁瘤形成心腔立体构型发生显著变化，心尖部和左室前侧壁明显膨出，铸型法测量左心室容积显示形成室壁瘤后容积显著增加。
6．左心室造影发现左室前侧壁室壁瘤形成，局部膨出、运动消失。
7．组织病理学检查显示LVA形成以后心肌细胞出现明显的空泡变性。
结论
1．同时结扎冠脉前降支和回旋支中段，可以形成面积较恒定的解剖性室壁瘤。
2．室壁瘤累及左室心尖部和前侧壁，不累及室间隔，适合采用非体外循环的方法实施室壁瘤手术。
3．腔内铸型法有助于研究左心室立体构型。
第二部分两种室壁瘤手术方式的对比研究
目的
对比研究外环缩和线性缝合两种术式在室壁瘤手术前后的效果实验方法
1．取室壁瘤兔24只，分成两组，每组各12只。
2．两种室壁瘤手术为外环缩缝合法和经典线性缝合法。外环缩缝合法是在室壁瘤与收缩正常的心肌交界处用3／OProlene线做荷包缝合，收紧结扎后消除反常运动的室壁瘤。经典线性缝合法是以大致平行于前降支的方向，采用双侧加人造血管垫片、连续、折叠缝合的方法，收紧结扎后消除反常运动的室壁瘤。
3．在成形术前和成形完毕当时经心尖部穿刺置管测量左室收缩压和舒张末期压力，术后2周经颈动脉再次测压。
4．成形术后2周行超声心动图检查，测量左心室前后径、长径、左室舒张末和收缩末期容积、射血分数。
5．成形术后2周取行左心室长轴和短轴解剖心脏，留大体病理标本。
6．成形术后2周取用琼脂做左心室腔内铸型，并测量铸型体容积。
结果
1．成形术后总存活率87.5％，共死亡3只兔，外荷包环缩组1只，夹心线性缝合组2只。
2．超声心动图结果：(1)两种术式成形后原室壁瘤基本消失。(2)两组左室前后径均有缩小趋势，但无显著性差异；左室长径显著性减小；室间隔和左室后壁厚度有减小趋势，但无显著性差异；左室舒张末期和收缩末期容积均显著性缩小；左室射血分数显著性升高。(3)两种术式比较：两组术后左室舒张末期容积无显著性差异，但外环缩组收缩末期容积显著性低于线性缝合组，射血分数显著性高于线性缝合组，且增加的幅度高于线性缝合组。
3．两种术式成形术后左室收缩压均明显升高，舒张末期压力均显著性下降，但线性缝合组的舒张末期压力明显高于外环缩缝合组。
4．大体病理标本显示，外环缩缝合组心肌束方向大致恢复正常，而线性缝合组左室前壁心肌束未能恢复正常。
5．左室腔内铸型结果：左室成形术后外环缩缝合左室立体构型恢复正常锥形结构，而线性缝合组左心室形状未能恢复锥形。
结论
1．荷包环缩缝合法与夹心线性缝合法均能改善较小室壁瘤的左室功能。
2．对于面积较小的室壁瘤，荷包环缩缝合法优于夹心线性缝合法。
3．LV腔内铸型用于室壁瘤术后LV腔研究，可以直观地反映成形前后左心室
腔地立体构型变化。
Objective
To find a proper way for creation of chronic left ventricular aneurysm in rabbit.
Materials and methods
1. 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 area
6. 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.
Results
1. 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.
Conclusion
1. Ligation of LAD and Cx at the middle point can produce LV aneurysm with
mean 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 ventricle
Objective
To compare purse reconstruction and linear repair the early results of the two procedures.
Materials and methods
1. 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-chamber
irrigation and heart anatomy were also repeated to show the geometric structure of LV after aneurysm surgery.
Results
1. 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.
Conclusion
Both purse reconstruction and linear repair can improve LV function and the former one is better than latter one in surgical intervention for aneurysm of mean
area 33.4±2.4%.
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