Research ArticleMEDICAL ROBOTS

Autonomous robotic intracardiac catheter navigation using haptic vision

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Science Robotics  24 Apr 2019:
Vol. 4, Issue 29, eaaw1977
DOI: 10.1126/scirobotics.aaw1977
  • Fig. 1 Autonomous intracardiac navigation using haptic vision.

    (A) Haptic vision sensor composed of millimeter-scale camera and LED encased in silicone optical window with working channel for device delivery. Endoscope acts as a combined contact and imaging sensor with optical window displacing blood between camera and tissue during contact. (B) Continuous contact mode in which catheter tip is pressed laterally against heart wall over entire cardiac motion cycle. Contact force is controlled on the basis of the amount of tissue visible at the edge of optical window as shown in inset. (C) Intermittent contact mode in which catheter is in contact with heart wall for a specified fraction, D, of the cardiac period (contact duty cycle). Insets show corresponding haptic vision images in and out of contact. Maximum contact force relates to contact duty cycle, D, as shown on plot and is controlled by small catheter displacements orthogonal to the heart wall. (D) Wall-following connectivity graph. Vertices, defined in legend, denote walls and cardiac features. Solid arcs indicate connectivity of walls and features, and dashed arcs indicate that noncontact transition is required. Wall-following paths through heart can be constructed as sequence of connected vertices. Paravalvular leak closure experiments described in the paper consist of paths a ➔ b ➔ ci′ ➔ ci, i = {1,2,3}.

  • Fig. 2 Paravalvular leak closure experiments.

    (A) Current clinical approach to paravalvular leak closure: image 1, catheter approaches valve; image 2, wire is extended from catheter to locate leak; image 3, vascular occluder is deployed inside leak channel. Although transapical access is illustrated, approaching the valve from the aorta via transfemoral access is common. (B) Robotic catheter in operating room. Graphical interface displays catheter tip view and geometric model of robot and valve annulus. (C) Two views of bioprosthetic aortic valve designed to produce three paravalvular leaks at 2, 6, and 10 o’clock positions. Blue sutures are used to detect tangent to annulus. Green sutures are used to estimate valve rotation with respect to robot. (D) Vascular occluder (AMPLATZER Vascular Plug II, St. Jude Medical, Saint Paul, MN) used to plug leaks.

  • Fig. 3 In vivo navigation completion times.

    (A) Navigation from apex of the left ventricle to the aortic annulus (Fig. 1D, a ➔ b ➔ c). (B) Circumnavigation of the entire aortic valve annulus (e.g., c1′ ➔ c1 ➔ c2 ➔ c3′ ➔ c2′ ➔ c3 ➔ c1′; Fig. 1D, inset). (C) Navigation from apex to paravalvular leak (Fig. 1D, a ➔ b ➔ ci′ ➔ ci). (D) Deployment of vascular occluder. Red bars indicate median, box edges are 25th and 75th percentiles, whiskers indicate range, and dots denote outliers. P values computed as described in the “Statistical analysis” section.

  • Fig. 4 Algorithmic robotic catheter design.

    (A) Computer model of optimized design composed of three tubes shown in adult left ventricle. Robot enters heart through apex and is depicted at 12 locations on the aortic annulus. (B) Fabricated catheter with haptic vision sensor shown inside 3D printed model of heart shown in (A). (C) Disassembled catheter showing its three precurved superelastic tubes. Tube parameters are given in Table 1.

  • Fig. 5 Software development cycle.

    In simulation, we replayed data from previous in vivo experiments to evaluate and debug software. New features were first implemented in the simulator either to address previously identified in vivo challenges or to extend robot capabilities. New software was then tested in the ex vivo model to check the desired functionality and to ensure code stability. Identified problems were addressed by iterating between in silico and ex vivo testing. New software features were then assessed with in vivo testing. The design cycle was then completed by importing the in vivo data into the simulator and evaluating algorithm performance.

  • Fig. 6 Occluder deployment system.

    The occluder, attached to a wire via a screw connection, is preloaded inside a flexible polymer delivery cannula. The delivery cannula is inserted through the lumen of the catheter into the paravalvular leak. A polymer deployment tube is used to push the occluder out of the delivery cannula. Once positioned, the occluder is released by unscrewing the wire.

  • Fig. 7 Maximum tissue force as a function of contact duty cycle.

    (A) We constructed a handheld instrument for the simultaneous measurement of tip contact force and contact duty cycle that combines a haptic vision sensor with a force sensor. (B) We made in vivo measurements of the temporal variations in contact force as a function of contact duty cycle on the aortic valve annulus. The insets show images from the haptic vision sensor at three points in the cardiac cycle. Note that the minimum force value is not necessarily zero because a small amount of tip contact with ventricular tissue can occur during systole when the valve moves away from the tip, but the ventricle contracts around it. This white (septal) ventricular tissue can be seen on the left side of the rightmost inset. (C) Maximum contact force as a function of duty cycle. Average values of maximum force are linearly related to contact duty cycle for duty cycles in the range of 0.35 to 0.7.

  • Table 1 Optimized parameter values for three tubes comprising the robotic catheter.

    Tube sections are labeled in Fig. 4B.

    Tube 1Tube 2Tube 3
    Section 1Section 1Section 1Section 2
    Outer
    diameter (mm)
    2.772.401.8751.875
    Inner
    diameter (mm)
    2.542.001.601.60
    Section
    length (mm)
    72.072.055.072.0
    Radius of
    curvature (mm)
    15015040.0∞ (straight)
    Relative bending
    stiffness
    0.9950.9950.3380.338

Supplementary Materials

  • Supplementary Materials

    The PDF file includes:

    • Legends for movies S1 and S2

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). Operator-controlled catheter navigation inside a 3D printed heart model.
    • Movie S2 (.mp4 format). In vivo autonomous catheter navigation.

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