case_images: PMC9845555_01
case_images: Electrocardiograms during sinus rhythm and His lead pacing. A: Sinus rhythm without left bundle branch block (LBBB), QRS 84 ms. B: Sinus rhythm with LBBB starting at a heart rate of 75 beats/min, QRS 153 ms. C: His lead pacing resulting in selective His capture with correction of bundle branch block at a unipolar threshold of 2 V / 1 ms, QRS 92 ms. D: His lead pacing resulting in selective His capture without correction of bundle branch block at a unipolar threshold of 0.9 V / 1 ms, QRS 149 ms.
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case_images: PMC9845555_01_gr1.jpg
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case_images: Holter monitoring, however, revealed rate-dependent LBBB coinciding with the patient's symptoms starting at a heart rate of 75 bpm (Figure 1). Device interrogation revealed 24% of ventricular pacing over time with a unipolar threshold of 2 V / 1 ms for selective His capture with LBBB correction and a unipolar threshold of 0.9 V / 1 ms for selective His capture without LBBB correction (Figure 1). Similarly, 3D simulation of left ventricular strain map during systole visualized improved ventricular deformation (Figure 3B, Supplemental Videos 1,2,3,4).
case_images: Exercise test before and after His bundle pacemaker (HBP) implantation. A: Electrocardiograms (ECGs) during exercise test before HBP implantation. B: ECGs during exercise test after HBP implantation. C: Exercise test before HBP implantation. D: Exercise test after HBP implantation. % refers to age- and sex-adjusted mean.
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case_images: Exercise stress testing demonstrated reduced exercise capacity (76 W = 60% of age- and sex-adjusted mean, VO2 max 14.4 mL/min/kg = 52% of age- and sex-adjusted mean) with a decreased maximal O2 pulse of 7 mL/beat (= 64% of age- and sex-adjusted mean), with the LBBB being present throughout the examination (Figure 2).
case_images: A: Left ventricular longitudinal strain without (left panel, pacemaker programmed to AAI 100/min) and with (right panel, pacemaker programmed to DDD 100/min with left bundle branch block [LBBB] correction) His pacing demonstrating improved global and segmental strain and mechanical dispersion. LV GLS = left ventricular global longitudinal strain; Mech. Disp. = mechanical dispersion. B: Three-dimensional simulation of left ventricular strain map during systole showing improved regional strain as observed from the apical view. A2C = 2-chamber view; A3C = 3-chamber view; A4C = 4-chamber view; Post = with His bundle pacing, pacemaker programmed to DDD 100/min with LBBB correction; Pre = without His bundle pacing, pacemaker programmed to AAI 100/min.
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case_images: Echocardiographic analysis during LBBB vs His bundle-pacing demonstrated improvement in segmental and global longitudinal strain (-13.2% vs -19.3%, respectively; Figure 3A), as well as improved mechanical dispersion (84 ms vs 51 ms, respectively; Figure 3), indicating increased ventricular deformation and synchronicity of contraction. Similarly, 3D simulation of left ventricular strain map during systole visualized improved ventricular deformation (Figure 3B, Supplemental Videos 1,2,3,4).