Doppler-Guided Acoustically Active Injection Catheter: Transendocardial Delivery Assessed by an Efficacy Testing Animal Model.

Percutaneous transendocardial injections of therapeutic agents into the myocardium may not always be effective. We used an animal model for assessing the efficacy of the injections using linoleic acid as a testing agent. Efficacious delivery into the myocardium of a beating heart was indicated by rapidly developed local myocardial necrosis and wall motion abnormalities using echocardiography. We employed this experimental model to test our innovative technology, an acoustically active injection catheter. The Doppler ultrasound-guided acoustically active injection catheter effectively delivers the substance to the myocardium but needs further technical improvements to minimize an unwanted systemic distribution of the agent.

Acoustically Active Catheter for Intracardiac Navigation by Color Doppler Ultrasonography.

Navigation of intracardiac catheters by echocardiography is challenging because of the fundamental limitations of B-mode ultrasonography. We describe a catheter fitted with a piezoelectric crystal, which vibrates and produces an instantaneous marker in color flow Doppler scans. The navigation learning curve was explored first in six pigs. Accuracy and precision of targeting with the navigation marker "off" (i.e., B-mode imaging) and "on" were assessed in another six pigs. Paired comparisons confirmed significantly (p = 0.04) shorter mean distances achieved in each pig with the color Doppler marker. Pooled (mean ± standard deviation) distance of the catheter tip from the target crystal was 5.27 ± 1.62 mm by B-mode guidance and 3.66 ± 1.45 mm by color Doppler marker navigation. Dye injection targeted into the ischemic border zone was successful in 8 of 10 pigs. Intracardiac catheter navigation with color Doppler ultrasonography is more accurate compared with conventional guidance by B-mode imaging.

Acoustically active injection catheter guided by ultrasound: navigation tests in acutely ischemic porcine hearts.

Catheters are increasingly used therapeutically and investigatively. With complex usage comes a need for more accurate intracardiac localization than traditional guidance can provide. An injection catheter navigated by ultrasound was designed and then tested in an open-chest model of acute ischemia in eight pigs. The catheter is made "acoustically active" by a piezo-electric crystal near its tip, electronically controlled, vibrating in the audio frequency range and uniquely identifiable using pulsed-wave Doppler. Another "target" crystal was sutured to the epicardium within the ischemic region. Sonomicrometry was used to measure distances between the two crystals and then compared with measurements from 2-D echocardiographic images. Complete data were obtained from seven pigs, and the correlation between sonomicrometry and ultrasound measurements was excellent (p < 0.0001, ρ = 0.9820), as was the intraclass correlation coefficient (0.96) between two observers. These initial experimental results suggest high accuracy of ultrasound navigation of the acoustically active catheter prototype located inside the beating left ventricle.

Percutaneous suture edge-to-edge repair of the mitral valve.

AIMS: To describe a new approach to percutaneous mitral valve repair and an illustrative first-in-man experience, we introduce a suture mediated "double orifice", "edge-to-edge" procedure which can be an effective surgical therapy for mitral regurgitation (MR) in selected patient. METHODS AND RESULTS: We describe a novel percutaneous approach to double orifice mitral repair utilising an intra-cardiac suture based system. The procedure was performed in 15 patients in four international centres. Endovascular suture based double orifice mitral repair was feasible with an acute reduction in the severity of MR by > or = 1 grade in nine of 15 patients. At 30 days improvement in MR appeared durable in six patients. Clinical utility was limited by technical difficulties, the inadequacies of current imaging modalities and suture dehiscence. CONCLUSIONS: Percutaneous endovascular suture based cardiac repair is feasible. However, in utilising the current device clinical benefit was limited and the repair not durable. In the future, similar endovascular approaches may enable more complex cardiac repair.

Beating-heart percutaneous mitral valve repair using a transcatheter endovascular suturing device in an animal model.

BACKGROUND: The edge-to-edge (Alfieri) technique for mitral valve repair is a versatile method of treating mitral insufficiency. Because of its simplicity, it has been applied in minimally invasive surgery, and recently, in the design of endovascular closed-heart devices. AIM: The purpose of this study was to evaluate the acute in-vivo safety and feasibility of a novel percutaneous mitral valve repair system based on Alfieri technique in an animal model. METHODS: Under general anesthesia, 11 pigs (90-100 kgs), underwent percutaneous Alfeiri procedure. The right femoral vein was punctured and the mitral valve was approached via a standard transeptal puncture. Combined intracardiac echo and fluoroscopic guidance was used. The procedure included: the positioning of a guide catheter for multiple access to the left atrium and for directing devices; the use of a therapy device to capture the free edge of the mitral valve leaflets using vacuum, and to deliver the suture to the valve and finally the fixation with a Nitinol suture clip, and trimming of the suture with a fastener catheter. RESULTS: Leaflet capture, suture placement, and suture-clip deployment was successful in all 11 animals. There were no acute cardiac or access site complications. Procedural time (from wire in left atrium to completion of the procedure was 18 +/- 9 min (range 9-30 min). Blood loss was 67 +/- 44 ml (range 0-125 ml). A double orifice configuration was visible by echocardiography at the end of the procedure in all animals. CONCLUSION: This acute animal study demonstrated the feasibility of a beating heart percutaneous Alfieri procedure in a non-diseased porcine valve using an endovascular suturing device to safely access the mitral valve, place a stitch through the mitral valve leaflets, and deploy a suture-clip that reproduces the surgical technique. Clinical application of this device in humans needs to be evaluated.

Intracardiac echocardiography for percutaneous mitral valve repair in a swine model.

BACKGROUND: High-quality live imaging assessment of cardiac valves and cardiac anatomy is crucial for the success of percutaneous catheter-based mitral valve (MV) repair techniques. We examined the use of intracardiac echocardiography (ICE) in providing online ICE images necessary for successful perctunaneous MV repair by Alfieri stitch technique-based percutaneous edge-to-edge device in a swine model. METHODS: ICE was performed in 20 healthy adult pigs (90 +/- 8 kg, mean +/- SEM). A 10F ICE catheter was advanced through the left femoral vein and the right jugular vein. Images were obtained from the right atrium, left atrium, right ventricle, and pulmonary artery. Fluoroscopy was used to locate the position of ICE catheter tip in different imaging windows. RESULTS: An echocardiographic protocol was developed for focused visualization of target cardiac structures during the process of percutaneous MV repair. This included visualization of interatrial septum to guide transeptal puncture; to confirm transit of guidewire into the left atrium, across the MV into the left ventricle and across the aortic valve into the aorta; to assist in central positioning of guide catheter in the left atrium above and then across MV leaflets; and to visualize middle scallops of anterior and posterior MV leaflets in short- and long-axis views. Finally, location and orientation of the orifice of the therapy catheter against each MV leaflet was visualized to enable successful capture of MV leaflets, to confirm successful deployment of suture and double orifice (figure of 8" appearance of MV, and finally to confirm central deployment of clip at the site of suture. CONCLUSION: An ICE protocol was developed to visualize serial cardiac structures to guide deployment of suture into the A2-P2 scallops of the MV and to confirm final result before release of clip.