Computerized tomography image correlation of His bundle/deep septal pacing location and outcomes: an analysis from the Canberra HIs bundle/deep septal Pacing Study (CHIPS)

Figures

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  Fig. 1. The Schematic diagram of relevant anatomy. Conduction system (green colour) with respect to the membranous septum (Me-triangular area), the upper end of the muscular septum (Mu -brown shaded) and septal leaflet of the tricuspid valve (TV-blue colour). A–C show muscular septum and membranous septum in the sagittal section depicting the His bundle in superior to the inferior plane; the three types of His bundles are shown. D and E show compact AV node and His bundle (green colour) in relation to Koch’s triangle as viewed from RA. The red line is the tendon of Todaro. Septal attachment of tricuspid valve (TV-blue colour) and coronary sinus (CS) opening also shown. In E, please note that the compact AV node and the His bundle are placed further anterior (distal) and superior to the CS mouth compared to D

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  Fig. 2. Four types of pacing observed in surface ECG. (See Appendix 3 for larger images). A His bundle pacing—Note ‘normal looking’ narrow QRS, normal QRS axis and retrograde P waves. B Para-Hisian pacing: Relatively broader QRS with lead II positive and lead III negative QRS. C Left bundle branch pacing: Narrow QRS with qR in V1, normal QRS axis. D Deep septal pacing: Note broader QRS and absence of lead II positivity and lead III negativity in comparison to para-Hisian pacing

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  Fig. 3. Relevant anatomy as seen in CT scan (see Appendix 3 for larger images). A Shows various components of the septum and relation to the septal leaflet of the tricuspid valve (STL). Me (blue arrows): membranous septum, Mu: muscular septum, A: atrial component of the membranous septum, V: ventricular component of the membranous septum, Ao: aorta, Me-Mu (red arrow): Junction between the membranous and muscular part of the septum. Corresponding schematic diagram of the CT image is given below. Please note that Me-Mu lies below the insertion of STL to the septum giving rise to the ventricular component of the membranous septum. B shows an absent ventricular portion of the membranous septum

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  Fig. 4. Location of the lead in His bundle pacing. (See Appendix 3 for larger images.) A shows HBP via RA with lead tip seen anteriorly near the right coronary cusp of the aortic valve (RCC) and away from the non-coronary cusp (NCC). Please note lead tip relationship with the Me-Mu junction (red arrow), septal leaflet of the tricuspid valve (STL-yellow arrow) and lead (L). Corresponding schematic diagram of the CT image is given below. In the schematic diagram, the membranous septum is coloured green and the muscular septum is coloured brown. Lead tip is seen at Me-Mu junction in this case. B shows HBP via RA who had lead tip beyond 2 mm from the Me-Mu junction. This patient had increased thresholds resulting in lead replacement on follow up. C shows HBP via RV. Lead tip is seen capturing muscular septum distally

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  Fig. 5. Location of the lead in para-Hisian pacing. (See Appendix 3 for larger images). A shows para-Hisian pacing via RA and the lead is seen posteriorly near non-coronary cusp of the aorta (NCC). Please note that the lead tip is much posterior and away from the Me-Mu junction. Me-Mu junction (red arrow), septal leaflet of tricuspid valve (STL -yellow arrow) and lead (L). Corresponding schematic diagram of CT image is given below. In the schematic diagram, the membranous septum is coloured green and the muscular septum is coloured brown. B shows para-Hisian pacing via RA and the lead tip is located beyond 2 mm from the Me-Mu junction. Note ‘atrial component’ of muscular septum. This patient had increased thresholds and required lead revision. Since the lead is not normally screwed deeply in HBP, the thick muscular septum might have led to high thresholds to capture the conduction system. C shows para-Hisian pacing via RV. Note that the lead tip is seen below the TV attachment into the RV

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  Fig. 6. Left bundle branch pacing. A shows main left bundle capture, B shows left posterior fascicle (LPF) capture, C shows left anterior fascicle (LAF) capture. (See Appendix 3 for larger images). Note narrow QRS and qR patterns in V1 in all ECGs. A shows normal QRS axis suggesting main left bundle capture. B shows the left axis deviation of QRS and C shows the right axis deviation of QRS suggesting capture of LPF and LAF respectively. D–F show corresponding CT images of the pacing lead location confirming existing understanding of the location of fascicles of the left bundle

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  Fig. 7. Depth of penetration of lead into the septum. A shows a case of deep septal pacing. LBBP is shown in B. Deep septal pacing lead has penetrated only up to 30% of depth into septum whereas LBBP lead tip is seen at 80% depth. Red arrow: lead tip