Ablation of atrial fibrillation in the rapid pacing canine model using a multi-electrode loop catheter
Boaz Avitall, MD, PhD, FACCa,
Arvydas Urbonas, MDa,
Scott Millard, BSEa,
Dalia Urboniene, MDa and
Ray Helms, MDa
a University of Illinois at Chicago, Section of Cardiology, Chicago, Illinois, USA
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Figure 1 The loop catheter system. (A) 8F with twenty-four 4-mm-long ring electrodes spaced 4 mm apart. (B) 8F with fourteen 12-mm-long coil electrodes spaced 2-mm apart. A soft, braided pull wire attached to the distal tip of the catheter can be retracted into the long guiding sheath to deflect the catheter tip to create a loop of various sizes.
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Figure 2 Fluoroscopic images of catheter positions for linear lesion creation. These fluoroscopic panels presented in the posteroanterior position of the C arm, showing the loop catheter deployed in the right atrium (RA) and left atrium (LA) in the positions where linear lesions were created. Standard high-RA and coronary sinus (CS) catheters and a transesophageal echocardiography probe are visible in some of the panels. (Position 1) Lesion encircling the pulmonary veins (PVs). The posterior portion of the circle is close to the mitral valve (MV) ring, as shown by the proximity of the loop to the CS catheter. The anterior segment is located under the left and right superior PVs. (Position 2) Left atrial circular lesion extending from the medial portion of the MV ring to the lateral wall of the LA. (Position 3) Left atrial circular lesion connecting the lateral portion of the MV ring and the superior portion of the atrial septum. (Position 4) Right atrial circular lesion from the inferior vena cava (IVC) across the isthmus, to the anterior septal region of the tricuspid valve ring, to the RA appendage (RAA), to the superior vena cava (SVC) and back to the IVC. LAA = LA appendage.
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Figure 3 Organization of the electrical activity before and after lesion creation. In many cases as linear lesions were created the local atrial electrical activity progressively organized to the point of conversion to normal sinus rhythm (shown on panel D during lesion creation in position 2). Panel B depicts the marked reduction in the local electrical activity amplitude as a result of the lesion created in position 1 when compared with the preablation recordings shown in panel A (all the recordings are bipolar: 1 and 2, 3 and 4, etc.). HRA = high right atrium; CS = coronary sinus; 1 to 24 = ring electrodes.
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Figure 4 Example of distal coronary sinus (CS) electrical isolation from the rest of the atria after linear lesions in positions 1 and 3. (A) Recordings showing distal CS isolation from the rest of the right atrium. (B) The loop catheter in position 1. The posterior portion of the circle is close to the mitral valve ring, as shown by the proximity of the loop to the CS catheter. The anterior portion is under the superior pulmonary veins. (C) Lesion gross pathology in the left atrium (arrows = lesions). The recordings in the high right atrium (HRA) and proximal CS between electrodes 1 and 2 are atrial fibrillation, but the distal CS recordings between electrodes 3 and 4 show sporadic depolarization. III = electrocardiogram surface lead; MECA = multi-electrode catheter ablation system bipolar recordings betweenelectrodes 1 and 2, 2 and 3, etc.
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Figure 5 Gross pathology and histology of ring versus coil lesions. (A and B) Healed radiofrequency lesions in position 1 created with the 4-mm ring electrode loop catheter. (C and D) Linear lesions created with the 12-mm coil electrode loop catheter. The 4-mm lesion is elevated and visibly defines each of the ring electrodes, whereas the 12-mm coil electrode lesions are flat. The histologic sections exemplify contiguous and transmural linear lesions. Collagen formation can be seen on both histologic panels. F = fibrous tissue; Ca = calcium deposition.
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