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Abstract
Cardiac interventional procedures are often performed under fluoroscopic guidance, exposing both the patient and operators to ionizing radiation. To reduce this risk of radiation exposure, we are exploring the use of photoacoustic imaging paired with robotic visual servoing for cardiac catheter visualization and surgical guidance. A cardiac catheterization procedure was performed on two in vivo swine after inserting an optical fiber into the cardiac catheter to produce photoacoustic signals from the tip of the fiber-catheter pair. A combination of photoacoustic imaging and robotic visual servoing was employed to visualize and maintain constant sight of the catheter tip in order to guide the catheter through the femoral or jugular vein, toward the heart. Fluoroscopy provided initial ground truth estimates for 1D validation of the catheter tip positions, and these estimates were refined using a 3D electromagnetic-based cardiac mapping system as the ground truth. The 1D and 3D root mean square errors ranged 0.25-2.28 mm and 1.24-1.54 mm, respectively. The catheter tip was additionally visualized at three locations within the heart: (1) inside the right atrium, (2) in contact with the right ventricular outflow tract, and (3) inside the right ventricle. Lasered regions of cardiac tissue were resected for histopathological analysis, which revealed no laser-related tissue damage, despite the use of 2.98 mJ per pulse at the fiber tip (379.2 mJ/cm2 fluence). In addition, there was a 19 dB difference in photoacoustic signal contrast when visualizing the catheter tip pre- and post-endocardial tissue contact, which is promising for contact confirmation during cardiac interventional procedures (e.g., cardiac radiofrequency ablation). These results are additionally promising for the use of photoacoustic imaging to guide cardiac interventions by providing depth information and enhanced visualization of catheter tip locations within blood vessels and within the beating heart.
Highlights
C ARDIAC interventional procedures, such as diagnostic electrophysiology and radiofrequency ablation, are often performed to diagnose and treat cardiac arrhythmias
We propose to overcome both of these challenges with a robotic photoacoustic system that holds the ultrasound probe and autonomously centers the probe on photoacoustic signals from the catheter tip, using the photoacoustic-based robotic visual servoing approach presented in our previous publications [33], [37]
The photoacoustic signals from the catheter tip remain well-visualized in the presence of tissue, which further emphasizes the expected benefits of using photoacoustic imaging to approximate the location of the cardiac catheter tip in the presence of acoustic clutter and out-of-plane motion
Summary
C ARDIAC interventional procedures, such as diagnostic electrophysiology and radiofrequency ablation, are often performed to diagnose and treat cardiac arrhythmias. During these procedures, a catheter is inserted into the femoral vein or artery in the patient’s thigh and navigated into the heart using fluoroscopic guidance [1], [2]. Lickfett et al [4] found that the mean fluoroscopy duration for atrial fibrillation procedures was greater than 60 minutes, resulting in greater than 1.0 Gy of peak skin radiation dose to the patient. While this radiation dose is not fatal, repeated exposure increases lifetime risk of excess fatal malignancies [4], [5]
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