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\begin{document}

\title{Successful Ablation of a Wide Complex Tachycardia with Distinct
Intra-Cardiac Electrograms}



\author[1]{yuval konstantino}%
\author[1]{Kirill Buturlin}%
\author[1]{Roi Westreich}%
\author[1]{Sergiy Bereza}%
\author[1]{Aviva Levitas}%
\author[1]{Leonel Slanovic}%
\author[1]{Moti Haim}%
\affil[1]{Soroka Medical Center}%


\vspace{-1em}



  
  \date{May 23, 2024}


\begingroup
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\selectlanguage{english}
\begin{abstract}
A 13-year-old boy was hospitalized after a syncopal episode that
occurred during exercise. He suddenly felt chest tightness, sweating and
palpitations, followed by a transient loss of conciseness. Upon
emergency medical team arrival, he was awake and oriented. Baseline ECG
showed sinus rhythm at a rate of 98 bpm, with narrow QRS, and no signs
of long QT, Brugada, or pre-excitation. Physical examination, blood
tests, 24 hours Holter monitoring, transthoracic echocardiography and
stress test were all within normal limits. Eight days later he
experienced a second episode of palpitations while walking to school.
ECG revealed regular wide complex tachycardia (WCT) at a rate of 200
bpm, with LBBB morphology that terminated with Adenosine (Figure 1). The
clinical tachycardia was easily induced by programmed electrical
stimulation (Figure 2A). Diagnostic electrophysiological maneuver
(Figure 2B) was followed by successful ablation, during which a unique
phenomenon was noted (Figure 3). What is the diagnosis of the
tachycardia and what are the unique findings noted during and after
ablation?%
\end{abstract}%



\sloppy


\textbf{Successful Ablation of a Wide Complex Tachycardia with Distinct
Intra-Cardiac Electrograms}

Short Title: ''Wide Complex Tachycardia with unusual electrograms''

Yuval Konstantino MD \textsuperscript{1,3}, Kirill
Buturlin\textsuperscript{1,3}, Roi
Westreich\textsuperscript{1,3}\textsubscript{,} Sergiy
Bereza\textsuperscript{1,3}, Aviva Levitas \textsuperscript{2,3}, Leonel
Slanovic \textsuperscript{2,3}, Moti Haim MD \textsuperscript{1,3}

\textsuperscript{1} Cardiac Electrophysiology and Pacing, Department of
Cardiology, Soroka University Medical Center, Beer-Sheva, Israel

\textsuperscript{2} Department of Pediatrics, Soroka University Medical
Center, Beer-Sheva, Israel

\textsuperscript{3} Faculty of Health Sciences, Ben-Gurion University of
the Negev, Beer-Sheva, Israel

\textbf{Corresponding author:}

Yuval Konstantino MD,

Soroka University Medical Center

Cardiology Department, Electrophysiology Unit,

Beer-Sheva, Israel

E-mail:

yuvkon@gmail.com\textbf{, yuvalkon@clalit.org.il}

Tel: 972-8-6244146

Fax: 972-77-4702768

None of the authors has any conflicts of interest

This research did not receive any specific grant from funding agencies
in the public, commercial, or not-for-profit sectors.

\textbf{Word count: 953}

\textbf{Case presentation}

A 13-year-old boy was hospitalized after a syncopal episode that
occurred during exercise. He suddenly felt chest tightness, sweating and
palpitations, followed by a transient loss of conciseness. Upon
emergency medical team arrival, he was awake and oriented. Baseline ECG
showed sinus rhythm at a rate of 98 bpm, with narrow QRS, and no signs
of long QT, Brugada, or pre-excitation. Physical examination, blood
tests, 24 hours Holter monitoring, transthoracic echocardiography and
stress test were all within normal limits. Eight days later he
experienced a second episode of palpitations while walking to school.
ECG revealed regular wide complex tachycardia (WCT) at a rate of 200
bpm, with LBBB morphology that terminated with Adenosine (Figure 1). The
clinical tachycardia was easily induced by programmed electrical
stimulation (Figure 2A). Diagnostic electrophysiological maneuver
(Figure 2B) was followed by successful ablation, during which a unique
phenomenon was noted (Figure 3). What is the diagnosis of the
tachycardia and what are the unique findings noted during and after
ablation?

\textbf{Discussion}

Baseline measurements revealed sinus rhythm with narrow QRS and short HV
interval of 25ms. VA conduction was concentric and decremental with VA
block at 290ms indicative of retrograde AV nodal conduction.

Incremental atrial pacing reproducibly induced wide complex tachycardia
of LBBB morphology following AH prolongation and HV shortening (Figure
2A), suggestive of right sided decremental accessory pathway
(AP).\textsuperscript{1}

Atrial extra-stimuli administered at the timing of His refractoriness
advanced the next V and the next A of the tachycardia (Figure 2B) which
is consistent with antidromic tachycardia. The differential diagnosis
includes ''long'' Mahaim atrio-fascicular AP and ''short'' decremental
atrio-ventricular AP. Activation mapping demonstrated earliest
ventricular activation at the antero-lateral aspect of the Tricuspid
annulus implying of ''short'' decremental AP rather than the apical
portion of the right ventricle as seen in atrio-fascicular accessory
pathway.\textsuperscript{2} Unexpectedly, a discrete AP potential
(Mahaim-like) was noted at the antero-lateral aspect of the Tricuspid
annulus, at sites of early ventricular activation during antidromic
tachycardia (Figure 3A). The AP was successfully ablated via internal
jugular approach at 10 o'clock position in left anterior oblique view.

Following ablation, a unique phenomenon was demonstrated with evidence
of infra-AP potential block and AP-ventricular dissociation during
atrial pacing without pre-excitation (Figure 3B). During Three-months
follow-up the patient was free of any arrhythmias.

Accessory pathways with decremental properties connect the right atrium
or the AV node with the right ventricle or the right bundle branch.
Although the historical report by Mahaim refers to a nodo-ventricular
accessory pathway, the term Mahaim has been adapted to describe other
decremental AP's with different anatomical features, including
atrio-fascicular and atrio-ventricular
pathways.\textsuperscript{1}Further classification of decremental AV
pathways into ``long'' pathways that insert into or near the right
bundle branch and ``short'' pathways that insert into the base of the
right ventricle was later described by Ha\selectlanguage{polish}ı\selectlanguage{english}ssaguerre in
1995.\textsuperscript{3} The latter pathways are characterized by atrial
and ventricular insertion immediately contiguous to the tricuspid
annulus as seen in the present case in which the distal insertion is
adjacent to the Tricuspid annulus.\textsuperscript{3}

Thus far, Mahaim potential, described as an AV nodal His like structure,
has been reported in ''long'' atrio-fascicular and atrio-ventricular
pathways \textsuperscript{1,2}, where it also facilitates successful
ablation. Typically, catheter ablation of these pathways is accomplished
by identifying the proximal and distal insertions and the recording of a
Mahaim potential at the tricuspid annulus or on the right ventricular
free wall.

In the present case, we have found that Mahaim-like potential can be
also identified in short decremental accessory pathway in which the
earliest ventricular activation is adjacent to the Tricuspid annulus
rather than the right bundle branch or the right ventricular free wall.
The location of the Mahaim-like potential was correlated with the
earliest site of ventricular activation during maximal pre-excitation
and assisted in localization of the AP and ultimately with successful
ablation. Post ablation, a unique phenomenon of an infra-AP potential
block was documented with evidence of AP-ventricular dissociation, which
proves our concept that the Mahiam-like potential was indeed associated
with the localization and ventricular insertion of the accessory
pathway.

\textbf{Figure 1}\selectlanguage{english}
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\textbf{Figure 2}\selectlanguage{english}
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\textbf{Hosted file}

\verb`image5.emf`  available at \url{https://authorea.com/users/490902/articles/574105-successful-ablation-of-a-wide-complex-tachycardia-with-distinct-intra-cardiac-electrograms}\selectlanguage{english}
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\textbf{Figure 3}\selectlanguage{english}
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\includegraphics[width=0.70\columnwidth]{figures/image9/image9}

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\textbf{Figure legends:}

\textbf{Figure 1:} Twelve lead electrocardiogram of the clinical
arrhythmia demonstrating wide complex tachycardia of LBBB morphology at
a rate of 200bpm.

\textbf{Figure 2A:} Induction of LBBB tachycardia by incremental CS
pacing following AH prolongation and HV shortening. Note that the last 4
paced beats are non-captured beats during LBBB tachycardia. CS 1,2:
distal coronary sinus; CS 9,10: proximal coronary sinus; His d: distal
His bundle. His p: proximal His bundle. HRA: high right atrium. H: His
deflection.

\textbf{Figure 2B:} Atrial extra-stimuli (arrow) during His
refractoriness. Baseline tachycardia cycle length is 310ms. His
deflection is marked on the distal His channel as H. The atrial
electrogram is marked as A and the ventricular electrogram as V. CS 1,2:
distal coronary sinus; CS 9,10: proximal coronary sinus; His d: distal
His bundle. His p: proximal His bundle. RV: Right ventricle.

\textbf{Figure 3A:} Wide complex tachycardia at a CL of 348ms. Ablation
catheter is placed at the ablation site. \textbf{3B} : CS pacing at
280ms after successful ablation. A: Atrium, V: Ventricle. CS 1,2: distal
coronary sinus; CS 9,10: proximal coronary sinus; ABL d: distal
ablation; ABL p: proximal ablation.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image14/image14}

\end{center}
\end{figure}

\textbf{References}

\begin{enumerate}
\tightlist
\item
  Katritsis DG, Wellens HJ, Josephson ME. Mahaim Accessory
  Pathways.~Arrhythm Electrophysiol Rev. 2017; 6:29-32.
\item
  Gandhavadi M, Sternick EB, Jackman WM, Wellens HJ, Josephson ME.
  Characterization of the distal insertion of atriofascicular accessory
  pathways and mechanisms of QRS patterns in atriofascicular antidromic
  tachycardia. Heart Rhythm. 2013; 10:1385-92.
\item
  Ha\selectlanguage{ngerman}ïssaguerre M, Cauchemez B, Marcus F, Le Métayer P, Lauribe P, Poquet
  F et al. Characteristics of the ventricular insertion sites of
  accessory pathways with anterograde decremental conduction properties.
  Circulation. 1995; 91:1077-85.
\end{enumerate}

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