ABSTRACT
Objective To adopt a novel domestic double-disc nitinol occluder to occlude the left atrial appendage of canines and evaluate its feasibility, safety and biocompatibility in experimental canine model. Methods Totally 12 healthy dogs were used in this study; their atrial septal was punctured to occlude the left atial appendage via the femoral vein. The position and effect of the implanted occluders were evaluated by electrocardiogram (ECG) monitoring, atrial septal puncture angiography, transesophageal echocardiography (TEE), and pathological examination immediately, 1, 3, and 6 months after the operation. Results Among the 12 dogs, 11were successfully implanted with the occluders immediately after operation, with the occluder in 1 case dropped after the operation. Two cases were firstly implanted with occluders of inappropriate size, which were withdrawn and successfully replaced by appropriate ones. The shape and location of the occluders were good as shown by TEE and left atrial angiography examination, with 3 cases having a little shunt and other cases completely occluded immediately after the operation as shown by TEE and left atrial angiography examination. There was no occluder shift, residual shunt or influence on coronary blood flow at 1, 3, and 6 months after the operation. It was shown that the left atrial appendage was completely blocked at 6 months after operation, and there was no thrombus formation on the surface of occluders or in the left atrium; there was no embolization or infarction in the liver, kidney or spleen, with the surface of the occluders completely covered with endothelial cells. Conclusion The novel self-made nitinol occluder has good biological compatibility, making t feasible to occlude the left atrial appendage via transcatheter approach, with satisfactory middle-term effects.
ABSTRACT
Objective To design and prepare a glass-shaped transthoracic left atrial appendage (LAA) reverse occluder and delivery system, and to evaluate the feasibility of transthoracic left atrial appendage reverse occlusion by in vitro reverse occlusion experiment. Methods We used fresh canine heart specimens and measured the anatomical parameters, including the long diameter, short diameter and perimeter of atrial appendage opening, the thickness of upper 1/3 left atrial appendage, the shortest distances from the edge of the opening of the atrial appendage to the left superior pulmonary vein, the left inferior pulmonary vein, and the mitral valve. A new glass-shaped left atrial appendage occluder was designed using nitinol wire, and the appendage occluder opening disk diameter and waist height were designed according to the average diameter of the opening of the atrial appendage and the thickness of upper 1/3 left atrial appendage. The delivery system comprised 9F delivery sheath, expansion sheath, preload sheath and a pushing cable. Delivery sheath was scaled which can be used to control the depth into the left atrial appendage, and expansion sheath head end had smooth transition shape which exposed only about 0.8 cm when inserted into the delivery sheath to prevent damage internal of tissue of heart. Ten isolated dog hearts were punctured at the center of the upper 1/3 axis of left atrial appendage outside under direct vision, and 9F sheath with scale was used to complete in vitro experiment of occlusion. The location and effect of the occluder were observed. Results Nine of the 10 heart specimens successfully underwent the occluding tests in vitro. It was showed that the occluder was well located, with the disc of the opening of left atrial appendage porting into the opening a little and the opening in an overdistraction state, and there was no influence on blood flow of pulmonary vein or function of the mitral valve. The ideal point of puncture was at the upper 1/3 long axis of left atrial appendage outside, and the purse-string suture should focus on this point. The puncture points located at the center of the left atrial appendage opening after removing the occluder postoperatively. Only 1 case failed because of low puncture point and unsuitable location of the occluder. Conclusion The glass-shaped transthoracic reverse occluder is well-designed and matched the anatomy of left the atrial appendage in experimental canine. The occluding effects are exact and meet the requirements of animal experiments in vivo.
ABSTRACT
<p><b>BACKGROUND</b>Lack of fluoroscopic landmarks can make valve deployment more difficult in patients with absent aortic valve (AV) calcification. The goal of this article was to evaluate the feasibility and effectiveness of transcatheter implantation of a valved stent into the AV position of a goat, assisted with a microcatheter which provides accurate positioning of coronary artery ostia to help valved stent deployment.</p><p><b>METHODS</b>The subjects were 10 healthy goats in this study. A microcatheter was introduced into the distal site of right coronary artery (RCA) through femoral artery sheath. A minimal thoracic surgery approach was used to access the apex of the heart. The apex of the left ventricle was punctured; a delivery catheter equipped with the valved stent was introduced over a stiff guidewire into the aorta arch. We could accurately locate the RCA ostia through the microcatheter placed in the RCA under fluoroscopy. After correct valve position was confirmed, the valved stent was implanted after rapid inflation of the balloon. The immediate outcome of the function of the valved stents was evaluated after implantation.</p><p><b>RESULTS</b>All ten devices were successfully implanted into the AV position of the goats. Immediate observation after the procedure showed that the valved stents were in the desired position after implantation by angiography, echocardiogram. No obstruction of coronary artery ostia occurred, and no moderate to severe aortic regurgitation was observed.</p><p><b>CONCLUSIONS</b>When the procedure of transcatheter implantation of a balloon-expandable valved stent into the AV position of goats is assisted with microcatheter positioning coronary artery ostia, the success rate of operation can be increased in those with noncalcified AV.</p>