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Introduction
In recent years, flutter circuits utilising epicardial structures have
been a focus of interest, as their occurrence has become more frequent
after endocardial catheter ablation and understanding the mechanisms of
complex macroreentrant tachycardias has become deeper through high
resolution mapping. As already known from several anatomical and
invasive studies, the coronary sinus (CS) musculature connects to the
right atrium (RA) as well as the left atrium (LA) forming electrical
interatrial connections. The connections to the LA can vary from 1 or 2
up to a wide continuum.
The coronary sinus often is a critical part of various forms of left
atrial macroreentrant tachycardias, mostly of common perimitral flutter,
and biatrial tachycardias, such as large circuits around both mitral and
tricuspid valves or biatrial flutter with perimitral circuit using only
the right atrial septum.
The CS musculature with its connections to RA and LA and the adjacent
myocardium of LA can serve substrate for a macroreentrant circuit
without utilizing other atrial areas. However, this kind of tachycardia
has only been reported once.
We herein report a rare case of a peri-CS atrial flutter in a female
patient after pulmonary vein isolation (PVI) four years ago and roof
line ablation due to roof-dependent atypical flutter during the same
procedure.
Case presentation
A 77-year-old female patient presented with shortness of breath and
tachycardia of 125bpm. The electrocardiogram showed \soutan atypical
flutter with atrial cycle length (CL) of 240msec. The flutter waves were
monophasic positive in II, III, aVF and V1-V2, negative in aVL and
isoelectric in I. A PVI-only procedure was performed four years ago. We
performed a new electrophysiological study upon admission. Written
informed consent was obtained. The procedure was performed under
conscious sedation. A steerable decapolar catheter (Inquiry, Abbott,
spacing 2-5-2) was introduced into the coronary sinus and showed a
“chevron” pattern. An activation map of the left atrium (NavX Ensite
Precision, Abbott, St. Paul, MN) was created using a high-density
mapping catheter (HD Grid catheter SE, Abbott) with support from a
steerable long sheath (Agilis, Abbott). LAT mapping and post pacing
interval (PPI) mapping revealed a roof dependant atrial flutter with a
“figure of 8” propagation around both pulmonary vein pairs. The
pulmonary veins were persistently isolated. Low voltage was documented
in the roof of LA. A roof line led to abrupt cycle length prolongation
to 270msec with CS propagation distal to proximal. The P-Wave was
biphasic negative in II, III, aVF, positive in V1-V2 and isoelectric in
I. The decapolar catheter had one large sharp signal per cycle on each
bipole Figure 1. An ultrahigh density activation mapping from
both LA and RA was performed. In the LA it seemed that the tachycardia
was centrifugal propagating from a focal exit in the inferolateral
mitral annulus with highly fractionated signals. The entrance of the
tachycardia to the RA was at the CS ostium. A focal mechanism of the
tachycardia was primarily assumed.