Self-expanding apical closure device for full-percutaneous closed-chest transapical valve procedures with large-sized introducer sheaths: first study in an animal model

OBJECTIVES

Available apical occluders do not fulfil requirements for full-percutaneous transapical valve procedures with large-sized introducer sheaths. A self-expanding closure device designed for closed-chest transapical valve procedures was tested in an animal model to verify safety, efficacy and thrombogenicity.

METHODS

Large-sized 21-Fr introducer sheaths (Certitude™ system for Sapien™ valves) were percutaneously placed in the ventricles of nine 3-month old minipigs. To seal the apical access, delivery catheters carrying folded self-expanding plugs were inserted. Then, the plugs were deployed while sheaths were removed. Echocardiograms verified tamponade and cardiac function, drains were not placed and a 3-month long aspirin therapy was administered. After 6 and 9 months, animals were euthanized and organs were analysed for macroembolic lesions search. Histological analysis was also performed.

RESULTS

Nine minipigs (weight: 28±3 kg) were used for this study. Eight plugs were successfully deployed in 8 ventricles without cardiac tamponade or ventricular dysfunction (success rate: 88.9%). In a failed procedure (the animal died after 1 month of cardiac tamponade), the outer disc of the apical plug got stuck in the intercostal space and did not correctly deploy. Post-mortem analysis in 8 minipigs at 6 (n = 4) and 9 months (n = 4) confirmed full deployment and good fixation of all plugs with internal surfaces covered by new endocardium. Macroscopic analysis of myocardium and vital organs showed absence of embolic lesions. Histological analysis showed absence of significant inflammatory infiltration and thrombosis.

CONCLUSIONS

In this animal model, self-expanding closure devices sealed 21-Fr large percutaneous apical accesses without acute tamponade, thrombosis or embolization. Further tests to evaluate full-percutaneous closed-chest apical procedures are required.

Control of a hybrid robotic system for computer-assisted interventions in dynamic environments

PURPOSE

Minimally invasive surgery is becoming the standard treatment of care for a variety of procedures. Surgeons need to display a high level of proficiency to overcome the challenges imposed by the minimal access. Especially when operating on a dynamic organ, it becomes very difficult to align instruments reliably and precisely. In this paper, a hybrid rigid/continuum robotic system and a dedicated robotic control approach are proposed to assist the surgeon performing complex surgical gestures in a dynamic environment.

METHODS

The proposed robotic system consists of a rigid robot arm on top of which a continuum robot is mounted in series. The continuum robot is locally actuated with McKibben muscles. A control scheme based on quadratic programming framework is adopted. It is shown that the framework allows enforcing a set of constraints on the pose of the tip, as well as of the instrument shaft, which is commanded to slide in and out through the entry point.

RESULTS

Through simulation and experiments, it is shown how the robot tool tip is able to follow sinusoidal trajectories of 0.37 and 2 Hz, while maintaining the instrument shaft pivoting along the entry point. The positioning and tracking accuracy of such system are shown to lie below 4.7 mm in position and [Formula: see text] in angle.

CONCLUSION

The results suggest a good potential for applying the proposed technology to assist the surgeon during complex robot-assisted interventions. It is also illustrated that even when using flexible hence relatively safe end-effectors, it is possible to reach acceptable tracking behaviour at relatively high frequencies.