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\begin{document}

\title{Left Bundle Branch Pacing Guided by Premature Ventricular Complexes
During Implant}



\author[1]{Shunmuga Sundaram}%
\author[2]{Pugazhendhi Vijayaraman}%
\affil[1]{Velammal Medical College Hospital and Research Institute}%
\affil[2]{Geisinger Heart institute}%


\vspace{-1em}



  
  \date{May 28, 2024}


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\selectlanguage{english}
\begin{abstract}
Left bundle branch pacing (LBBP) provides synchronized contraction of
ventricles and overcomes the limitation of His bundle pacing (HBP). The
pacing lead is placed deep inside the septum 1-1.5 cm apical to the
distal His bundle region. The criteria for capture of left bundle branch
(LBB) have been proposed but it has never been validated. LBB potentials
may not be demonstrable in all patients. Premature ventricular complexes
(PVC) are often noted while positioning the lead in the interventricular
septum. The morphology of the PVCs depends on the depth of the lead in
the septum. We describe a novel method for lead placement to capture LBB
by monitoring the morphology and duration of PVCs in four patients with
different pacing indications. Rapid rotations were stopped immediately
on observing a PVC with narrow QRS duration and qR (right bundle branch
delay) pattern in lead V1. LBB potential and non-selective to selective
LBB capture could be demonstrated after placing the lead. PVC guided
lead placement would help in final positioning of the lead, avoid
perforation into left ventricle cavity and to confirm conduction system
capture.%
\end{abstract}%



\sloppy


\textbf{Title Page}

\emph{INNOVATIVE TECHNIQUES}

Left Bundle Branch Pacing Guided by Premature Ventricular Complexes
During Implant

\textbf{Author Details}

Dr. Shunmuga Sundaram Ponnusamy MD., DM., PDF (EP)

Assistant Professor, Department of Cardiology

Velammal Medical college hospital and research institute

Madurai, Tamilnadu, India

Dr. Pugazhendhi Vijayaraman, MD., FHRS Professor of Medicine, Geisinger
Commonwealth School of Medicinie Geisinger Heart Institute, MC 36-10
1000 E Mountain Blvd, Wilkes-Barre, PA 18711

Disclosures:

SSP: None

PV: Honoraria, consultant, research, fellowship support: Medtronic,
consultant: Boston

Scientific, Abbott, Biotronik, Eaglepoint LLC

Key Words: Left bundle pacing, premature ventricular complex, heart
failure, AV junction ablation

Word count: 1194 words

\emph{INNOVATIVE TECHNIQUES}

Left Bundle Branch Pacing Guided by Premature Ventricular Complexes
During Implant

\textbf{Introduction}

Physiological pacing has witnessed a rapid growth in the last decade.
His bundle pacing (HBP) provides electrical and mechanical synchrony but
limited by high pacing thresholds and lead revisions\textsuperscript{1}.
Left bundle branch pacing (LBBP) has recently been shown to be a
promising alternative to HBP. Several criteria for left bundle capture
have been proposed\textsuperscript{2}, but needs to be validated. We
describe premature ventricular complex (PVC) guided lead implantation as
a novel approach to perform LBBP.

\textbf{Case 1:}

A 35 years old woman with non-ischemic cardiomyopathy (NICM), left
bundle branch block (LBBB) and left ventricular (LV) dysfunction
(ejection fraction 28\%) was referred for cardiac resynchronization
therapy (CRT). After obtaining informed consent, LBBP was performed
using C315 His sheath and 3830 Selectsecure\textsuperscript{tm} lead
(Medtronic, Minneapolis, MN). The pacing lead was positioned deep inside
the septum 1.5 cm apical to the distal His bundle region by 4-5 rapid
turns. PVCs with changing morphology were noted during lead advancement.
Rotation was stopped immediately on observing a PVC (VES1) with narrow
QRS duration and qR (right bundle branch {[}RBB{]} delay) pattern in
lead V1 (Figure 1A). No potentials were noted during baseline LBBB
rhythm. Non-selective to selective capture of left bundle branch (LBB)
could be demonstrated by change in QRS morphology and discreet local
ventricular electrogram at near threshold output (Figure 1C). Pacing
threshold was 0.4V at 0.5ms and unipolar pacing impedance of 670 ohms.
LBB paced QRS morphology mimicked VES1 with duration of 122ms and peak
left ventricular activation time (pLVAT) in lead V5 of 65ms (Figure 1B).
AV interval was optimized to correct the RBB delay (Figure 1D).\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

\emph{Figure 1: \textbf{Left bundle branch pacing for NICM with LBBB}. A
-- PVCs with changing morphology from QS to qR pattern (VES1) in lead V1
noted during rapid rotation. B -- LBB paced QRS morphology mimicked VES1
with duration of 122ms and pLVAT of 65ms. C- Non selective (first 2
beats) to selective LBB capture (last 2 beats) at near threshold output.
D- Final 12 lead electrocardiography (ECG) after RBB delay correction by
optimizing the AV delay (QRS duration 98ms). His d -- distal His bundle
electrogram, LBB and LBU -- Pacing lead electrogram bipolar and unipolar
respectively}

\textbf{Case 2:}

A 72 years old man was referred for the management of permanent atrial
fibrillation with uncontrolled ventricular rates and LV dysfunction.
Echocardiography showed moderate mitral regurgitation with LV ejection
fraction of 32\%. Atrioventricular junction (AVJ) ablation with
physiological pacing option was recommended. LBBP was attempted as
previously described. PVCs of changing morphology were noted while
placing the lead deep inside the septum. Rotation was stopped
immediately after observing PVC (VES2) with narrow QRS duration and qR
in lead V1 (Figure 2A). Non-selective to selective capture of LBB could
be demonstrated at near threshold output (Figure 2D). LBB paced QRS
mimicked VES2 with duration of 124ms and pLVAT of 65ms (Figure 2B). The
pacing threshold was 0.6V/0.5ms and lead impedance of 730 ohms. LBB
potential was recorded on the LBBP lead electrogram (LBB-ventricular
interval of 25ms, Figure 2C). AVJ ablation was completed using an
irrigated-tip ablation catheter.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

\emph{Figure 2: \textbf{LBBP and AVJ ablation}. A -- PVCs with changing
morphology during lead rotation. B- LBB paced QRS mimicked VES2 with
duration of 124ms and pLVAT 65ms. C- Pacing lead electrogram (LBB)
showing sharp LBB potentials (LB Po) preceding the local ventricular
electrogram. D -- Non selective (first 2 beats) to selective (last 2
beats) capture of LBB. His d and p -- His distal and proximal
electrogram, LBB and LBU -- Pacing lead electrogram bipolar and
unipolar, RVA -- right ventricular electrogram, His Po -- His bundle
potential}

\textbf{Case 3:}

A 65-year-old woman with NICM, LBBB and LV dysfunction (ejection
fraction 30\%) was referred for CRT. LBBP was performed using C315His
sheath and 3830 Selectsecure\textsuperscript{tm} lead. While positioning
the lead deep inside the septum, PVCs with changing morphology were
noted. Rotation was stopped immediately on observing PVC (VES3) with
narrow QRS duration and qR in lead V1 (Figure 3A). No potentials were
noted during baseline LBBB rhythm. The pacing threshold was 0.3V at
0.5ms and pacing impedance of 580 ohms. The final LBB paced QRS
morphology mimicked VES3 (Figure 3B) with duration of 124ms (pLVAT --
78ms). RBB delay was corrected by optimizing the AV interval and pacing
output (Figure 3C).\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

\emph{Figure3: \textbf{LBBP for NICM with LBBB}. A -- Rapid premature
ventricular complexes during lead rotation. B- LBB paced QRS mimicked
VES4 with duration of 124ms and pLVAT of 78ms. C -- Final 12 lead ECG
after correcting RBB delay by AV interval optimization (QRS duration
108ms)}

\textbf{Case 4:}

A 73 years old woman with normal LV function presented with symptomatic
complete heart block. LBBP was done using 3830
Selectsecure\textsuperscript{tm} lead and C315His sheath. The pacing
lead was positioned deep inside the septum by 4-5 rapid turns. PVCs with
changing morphology were noted during lead advancement. Lead rotation
was stopped immediately after observing narrow complex PVC (VES4) with
qR pattern in lead V1 (figure 4A). Electrograms from the pacing lead
demonstrated sharp left bundle potential (Figure 4C) preceding the
ventricular electrogram (LB-ventricular interval of 20ms). Pacing
threshold was 0.4V at 0.5ms and lead impedance was 680 ohms. The paced
QRS morphology mimicked the narrow PVC morphology (VES4) with QRS
duration of 114ms with pLVAT in lead V5 of 70ms (Figure 4B). RBB delay
was corrected by optimizing pacing output to allow anodal capture
(Figure 4D)\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image4/image4}

\end{center}
\end{figure}

\emph{Figure 4: \textbf{LBBP for Complete heart block}. A -- PVCs during
LBB lead placement. B -- Paced QRS morphology mimicked VES4 with
duration of 114ms and pLVAT of 70ms. C -- Pacing lead electrogram
showing sharp LBB potential (LB Po) preceding the local ventricular
electrogram. C -- Final 12 lead ECG after RBB delay correction by anodal
capture (QRS duration 100ms). His d and p -- His distal and proximal
electrogram, LBB and LBU -- Pacing lead electrogram bipolar and
unipolar, RVA -- right ventricular electrogram, His Po -- His bundle
potential}

\textbf{Discussion:}

Left bundle branch pacing is a promising alternative to HBP. Presence of
right bundle branch conduction delay pattern (qR in lead V1) and
demonstration of LB potentials are often used as criteria for LBB
capture\textsuperscript{2,3}. LBB potentials may not be demonstrable in
all patients, especially in those with LBBB. Transition in QRS
morphology from non-selective to selective LB capture or nonselective to
LV septal capture may be noted at near threshold
outputs\textsuperscript{4}. Rapid rotation of the pacing lead is
necessary to achieve deep penetration of the interventricular septum.
Perforation into the LV cavity can occur if the lead is advanced too
rapidly. Premature ventricular complexes are commonly noted while
positioning the lead in the interventricular septum. The PVC morphology
depends on the depth of the lead in the septum. We observed gradual
change in morphology from wide QRS with QS morphology in lead V1 to
narrow QRS with qR pattern in lead V1 as the lead penetrated the septum
from right ventricular side to the LBB area. In all four cases, rapid
rotations were stopped as soon as PVCs with narrow QRS/qR pattern were
observed (VES1, VES2, VES3 and VES4). Paced QRS morphology matched the
PVC morphology with short and constant pLVAT at differential pacing
(high and low output). Though the pacing indications varied in these
patients PVC morphology predicted LB capture and guided in deciding the
lead depth. LBB potentials were noted in two patients (CHB and AVJ
ablation cases). It is possible to record LBB potentials in patients
with LBBB during PVCs of RBB morphology if continuous recording can be
performed during lead rotations. Lack of a revolving connector-pin
during lead rotations is a limitation with the current implant
technique. Further rotations were avoided, preventing perforation of
septum. Monitoring the change in PVC morphology and QRS duration during
lead fixation would help in final positioning of the LBB pacing lead and
confirming conduction system capture.

Since the initial description of LBBP, multiple studies have shown the
safety and efficacy of left bundle branch pacing. Huang et
al\textsuperscript{5}, demonstrated 97\% success rate in LBBP for
non-ischemic cardiomyopathy and LBBB along with significant improvement
in LV ejection fraction at 1 year. A large retrospective multicenter
study by Vijayaraman et al\textsuperscript{6}, showed 85\% success rate
in achieving cardiac resynchronization therapy by LBBP (277 out of 325
patients). Improvement in LVEF was noted in both ischemic and
non-ischemic cardiomyopathy and similarly in patients with LBBB and
non-LBBB. Conduction system pacing combined with AV node ablation showed
a high success rate in persistent atrial fibrillation patients with
heart failure and ICD indication\textsuperscript{7}. This study also
showed significant improvement in LV function and reduction in
inappropriate shocks.

LBBP is emerging as a promising option to deliver physiological pacing.
Though several criteria have been proposed to confirm capture of left
bundle, prospective studies are necessary to validate. PVC guided lead
placement would help in final positioning of the lead and avoid septal
perforation into LV cavity

\textbf{References}

\begin{enumerate}
\tightlist
\item
  Subzposh FA, Vijayaraman P. Long-term results of His bundle pacing.
  Card Electrophysiol Clin 2018;10:537--42.
\item
  Huang W, Chen X, Su L, et al. A beginner's guide to permanent left
  bundle branch pacing. Heart Rhythm 2019;16;1791-6
\item
  Vijayaraman P, Subzposh FA, Naperkowski A, et al. Prospective
  evaluation of feasibility, electrophysiologic and echocardiographic
  characteristics of left bundle branch area pacing. Heart Rhythm
  2019;16:1774--1782
\item
  Vijayaraman P, Huang W. Atrioventricular block at the distal His
  bundle: Electrophysiological insights from left bundle branch pacing.
  HeartRhythm Case Rep. 2019;5(4):233-6
\item
  Huang W, Wu S, Vijayaraman P, et al. Cardiac resynchronization therapy
  in patients with non-ischemic cardiomyopathy utilizing left bundle
  branch pacing. J Am Coll Cardiol EP 2020;(article in press)
\item
  Vijayaraman P, Sundaram S, Cano O, et al. Left bundle branch pacing
  for cardiac resynchronization therapy: Results from international LBBP
  collaborative study group. HRS 2020 -- Late breaking clinical trial
\item
  Wang S, Wu S, Xu L, et al. Feasibility and efficacy of His bundle
  pacing or left bundle pacing combined with AV node ablation in
  patients with persistent atrial fibrillation and implantable
  cardioverter-defibrillator therapy. J Am Heart Assoc.
  2019;17;8(24).e014253. doi 10.1161/JAHA 119.014253.
\end{enumerate}\selectlanguage{english}
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