Yu-feng Zhu

Animal Experimental Study of the Fully Biodegradable Atrial Septal Defect (ASD) Occluder

This study was conducted to evaluate the feasibility, safety, biocompatibility, and degradation features of a fully biodegradable occluder for closure of atrial septal defect (ASD) in an acute canine model. The ASD was created in 20 healthy mongrel dogs by the brockenbrough needle, and the fully biodegradable occluders were implanted by self-made delivery system. The success rate and complications were observed. Acute ASD models were successfully created in 18 dogs, and 16 occluders were successfully implanted in the ASD models. Animals were sacrificed at different times after procedure. The cardiac gross anatomy showed that all occluders were stable in the interatrial septum, no vegetation or thrombus formation was observed on the surface of all occluders. They were embedded into endogenous host tissue gradually at 12-week follow-up. Different periods of pathological observations suggested that the occluders degraded gradually over about 24 weeks and essentially became an integral part of the septum. Transcatheter closure of ASD in acute canine model using the fully biodegradable ASD occluder has the potential of a high successful rate of technique, excellent biocompatibility, and fewer complications with adequate, immediate, and short-term results.

Development and preclinical evaluation of a biodegradable ventricular septal defect occluder.

This study evaluated the feasibility, effectiveness, and safety of a biodegradable (BD) occluder for closure of ventricular septal defect (VSD) in an acute canine model.

Transcatheter closure of medium and large congenital coronary artery fistula using wire-maintaining technique

BACKGROUND For medium and large coronary artery fistula (CAF), the initially selected device sometimes has to be exchanged by reconstruction of track wire loop due to the complexity of CAF. OBJECTIVES We sought to evaluate the feasibility and safety of transcatheter closure of medium and large CAF by using the wire-maintaining technique (WMT). METHODS A total of 18 patients aged 15-56 years with congenital CAF underwent percutaneous transcatheter closure by WMT between April 2006 and October 2012. The immediate and long-term outcomes were evaluated. RESULTS Of the 18 patients (11 females), 16 (88%) underwent successful transcatheter closure of fistula using WMT. The CAFs originated from the right coronary artery (67%), the left circumflex coronary artery (28%), and the left anterior descending coronary artery (5%). The drainage sites were the right ventricle (56%), right atrium (22%), left ventricle (11%), and coronary sinus (11%). The mean diameter of fistulas was 9.5±1.71mm and mean size of the devices was 13.6±3.03mm. An angiogram following device deployment showed complete occlusion in 11 patients, mild residual shunt in 2 patients, and trivial residual shunt in 3 patients. One patient had transient ST-T wave changes, and one patient had hemolysis after the procedure. Follow-up ranged from 1 month to 54 months (median 39 months). Echocardiogram showed trivial residual shunt in 3 patients at 6-month follow-up and in 1 patient at 12-month follow-up. Coronary artery thrombosis was observed in 1 patient by multislice computed tomography at 12-month follow-up. CONCLUSION For those patients with medium and large complex fistula, transcatheter closure of CAF can be performed by using the wire-maintaining technique.

Improved transcatheter aortic valve implantation for aortic regurgitation using a snare loop-assisted device: the first preclinical experience.

Transcatheter aortic valve implantation (TAVI) is an effective percutaneous treatment for high‐risk patients with severe symptomatic aortic stenosis. However, TAVI is rendered less effective in patients with noncalcified aortic valve disease because noncalcified aortic valves lack an anchor site for the implanted stent, causing the stent to relocate to an unexpected position. In this study, we developed an improved TAVI with a snare loop‐assisted device, and evaluated the feasibility and safety of this strategy in noncalcified aortic valve disease.

Balloon-expanding stent and delivery system for transcatheter aortic valve implantation: An animal study

Objective To evaluate the feasibility and satefy of transcatheter aortic valve implantation in animals by using a new balloon-expanding valved stent. Methods The balloon-expandable stent is made from cobalt-based alloy material and designed with a tubular, slotted structure. Fresh bovine pericardium was treated, sutured and fixed on the balloon-expandable stent. Ten healthy sheep (five males and five females), weighing an average of (25.16 ± 1.83) kg, were selected to undergo transcatheter implantation of the valve stents. The function of the valve stent was evaluated by angiography, echocardiography, and histology six months after the procedure. Results Of the ten experimental sheep, two sheep died during the operation because the higher position of the artificial valve affected the opening of the coronary artery. We successfully implanted the aortic valve stent in other eight sheep; however, one sheep died of heart failure two weeks after the operation due to the lower position of the valve stent. The valve stents were implanted in the desired position in seven sheep. Ascending aortic angiographic and autoptic findings immediately after the operation confirmed the satisfactory location and function of the valved stent. Echocardiography, angiography, and histology at six postoperative months confirmed the satisfactory location and function of the valve stent. Conclusion We successfully implanted our new valve stent as a replacement of native aortic valve via the transcatheter route with satisfactory outcome.

Transcatheter Aortic Valve Implantation Assisted with Microcatheter: A New Method to Avoid Coronary Artery Obstruction

Background: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. Methods: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. Results: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. Conclusions: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.

Establishment of a canine model of a percutaneous acute aortic valve regurgitation

Objective To explore the feasibility and effectiveness of establishing an aortic valve regurgitation canine model by minimally invasive peripheral vascular catheter method.Methods A total of 10 healthy canines were selected in this study.An aortic insufficiency animal model was established by percutaneous femoral artery puncture and aortic dilatation.Aortic angiography and transthoracic echocardiography were used to evaluate aortic valve regurgitation immediately after operation.Results Aortic valve regurgitation animal models were successfully established in all the 10 canines.Two canines died of acute left ventricular failure due to the large aortic regurgitation after the operation.Six surviving canines had moderate aortic regurgitation and two had slight aortic regurgitation;they survived for more than 1month.Conclusion It is feasible to establish an aortic regurgitation canine model by minimally invasive peripheral vascular catheter method.

Transthoracic left atrial appendage reverse occlusion:instrument development and in vitro animal experiment

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 1/3left 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 1/3left atrial appendage.The delivery system comprised 9Fdelivery 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 0.8cm 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 1/3axis of left atrial appendage outside under direct vision,and 9Fsheath 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 1/3long 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 1case failed because of low puncture point and unsuitable location of the occluder.Conclusion The glass-shaped transthoracic reverse occluder is welldesigned 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.