Transcatheter epicardial pacing of the human Bachmann’s bundle via the transverse sinus: Novel technique to expand transcatheter cardiac intervention

Figures

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  Figure 1. Baseline electrocardiograms, chest radiographs, and electrogram. 12-lead electrocardiogram during sinus rhythm (A, left) exhibits low amplitude in the P wave. P-wave duration measured from lead aVL was 113 milliseconds. During right atrial appendage and biventricular pacing (A, right), P waves are hardly detected, and thus, P-wave duration could not be measured. The frontal (B) and lateral (C) chest radiographs show the atrial lead implanted within the right atrial appendage (arrowheads). The intracardiac electrogram (D) during right atrial appendage and biventricular pacing (atrioventricular [AV] delay of 170 milliseconds, adaptive cardiac resynchronization therapy mode) revealed simultaneous left atrial (black asterisks) and ventricular (red asterisks) signals within the QRS wave, as recorded in the coronary sinus (CS). ABL = ablation catheter; CS = coronary sinus catheter; d = distal; p = proximal.

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  Figure 2. Fluoroscopic image and intracardiac electrocardiogram of the ablation catheter in the transverse sinus. The tip of the ablation catheter (orange arrowheads) is located posterior to the catheter (green arrowheads) placed in the ascending aorta in the right anterior oblique view (A). With the support of a deflectable guiding sheath, the ablation catheter, via the inferior epicardial approach, enters the transverse sinus from its left-side entrance and reaches the medial border of the vertebral column, but still lateral to the catheter placed in the ascending aorta and far lateral to the leads in the superior vena cava in the left anterior oblique view (B). Intracardiac electrogram recorded by the ablation catheter during right atrial appendage and biventricular pacing (with prolonged AV delay of 360 milliseconds) displays separation of atrial signals (black asterisks) from the QRS wave and fractionated Bachmann’s bundle signal (blue asterisks) 88 milliseconds after the pacing spike. The left atrial signal in the proximal CS electrode is recorded 208 milliseconds after the atrial pacing spike, also delayed by 120 milliseconds from the onset and by 55 milliseconds from the endpoint…

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  Figure 3. Intracardiac electrogram during Bachmann’s bundle pacing from the epicardial side using the ablation catheter. Bachmann’s bundle was paced from the epicardial side through the transversus sinus using the ablation catheter (A), which revealed shortening of the conduction time from pacing to the left atrium (from 208 milliseconds to 58 milliseconds). By the shortening of this interval and prolonged AV delay, optimal separation between the left atrial signals (black asterisks) and ventricular signals (red asterisks) was confirmed, preventing AV dyssynchrony. All beats except the second beat (premature ventricular contraction from the left ventricular summit) are intrinsic right ventricular excitation-gated biventricular pacing activated by the ventricular sense response program. The sequence of atrial signals recorded by the CS catheter also changed from Chevron-shaped (Figure 2) to distal-to-proximal propagation. A wave in the transmitral flow (arrowhead) is restored after the procedure without truncation (B). ABL = ablation catheter; AV = atrioventricular; d = distal; p = proximal; RV = right ventricle.

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  Figure 4. Frontal and lateral radiographs and electrocardiogram of Bachmann’s bundle pacing lead implantation. Bachmann’s bundle pacing lead (yellow arrowheads) directs towards the posteromedial direction, whereas the old right atrial appendage pacing lead (red arrowheads) directs towards the anteromedial direction (A, B). P wave detection during endocardial Bachmann’s bundle pacing remains challenging from the standard electrogram (C).

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  Figure 5. Contrast-enhanced thoracic computed tomography after Bachmann’s bundle pacing lead implantation. Multiplanar reconstruction images viewed from the inferior (A) and left anterior oblique (B) views depict the tip of the lead placed at the posteromedial area of the atriocaval junction adjacent to the interatrial portion of Bachmann’s bundle covering the anterosuperior interatrial groove. Volume-rendered images viewed from the right (C) and left (D) anterior oblique directions, reconstructed with virtual transverse sinus (yellow) and Bachmann’s pacing lead (red), depict the relationship between the lead and surrounding structures relative to the transverse sinus.

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  Figure 6. Clinical anatomy of the transverse sinus relevant to Bachmann’s bundle pacing. Volume-rendered images are reconstructed with the virtual transverse sinus (yellow) and Bachmann’s bundle pacing lead (red) and are viewed from the left anterior oblique (A, B) and superior (C) directions. As the transverse sinus is located along the right anterior to left posterior direction (C), its en-face view can be obtained from the left anterior oblique direction (Figure 5) with (A, B) or without cranial angulation (Figure 5). LAO = left anterior oblique.

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  Figure 7. Review of the transcatheter epicardial pacing site of Bachmann’s bundle. By using identical right (A) and left (B) anterior oblique directions applied during transcatheter epicardial Bachmann’s bundle pacing, volume-rendered images (C–H) are reconstructed with the virtual transverse sinus (yellow), right atrial appendage lead, and Bachmann’s bundle pacing lead. Such a 3-dimensional comparison can clarify the site of transcatheter epicardial pacing (green arrowheads) via the transverse sinus using its left-side entrance. It is located on the anterior wall of the left atrium just medial to the left atrial appendage orifice, before passing under the pulmonary trunk. That location is 39.8 mm lateral to the endocardial Bachmann’s bundle pacing site (yellow arrowheads).

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  Figure 8. Relevant anatomy of the interatrial portion of Bachmann’s bundle and transverse sinus. The virtual dissection image reconstructed from a pressure-perfused and fixed heart viewed from the inferior direction (A), with its corresponding real sample (B), highlights the structures surrounding Bachmann’s bundle, including the superior vena cava, precaval bundle, crista terminalis, anterosuperior interatrial groove, ascending aorta, and left atrial appendage. The transverse sinus (asterisks) is located between the ascending aorta and Bachmann’s bundle. Identical histology proves Bachmann’s bundle as an epicardial interatrial connection facing the transverse sinus (C). The intercaval bundle (arrowheads) is also observed as an epicardial myocardial bundle connecting the sinus venarum with the antrum of the right superior pulmonary vein. It takes an oblique course within the interatrial groove.

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  Figure 9. Entrances to the transverse sinus. Pressure-perfused and fixed heart viewed from the right anterior (A) and left posterior (B) oblique directions denote the right- and left-side entrances (arrowheads) to the transverse sinus. The right-side entrance is located between the atriocaval junction and the ascending aorta. The left-side entrance is located between the base of the left atrial appendage and the left pulmonary artery. If you can lift each appendage away from adjacent arterial trunks, it is also feasible to enter the space medially to each appendage. Volume-rendered images reconstructed from the live heart datasets of the present case demonstrate the same anatomy, viewed from the identical directions (C, D).

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  Figure 10. Biplane fluoroscopic image of another case with transcatheter epicardial ablation with an ablation catheter passing through the transverse sinus. An inferior approach is used for epicardial access. Images are viewed from the right (A) and left (B) anterior oblique directions and captured during the right coronary angiography. The ablation catheter (arrowheads) passes through the transverse sinus, entering from the left-side entrance and exiting from the right-side entrance before reaching the basal inferior right ventricle near the distal right coronary artery.