CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 3, April 2013
e10
AFRICA
In September 2010 the patient again presented with a
sustained monomorphic VT. The morphology was different from
that seen in 2007 (Fig. 1). A cardioversion was performed and
maintenance amiodarone (200 mg daily) was commenced after
intravenous loading.
In October 2010 he was re-admitted in VT with the same
morphology (Fig. 1). Urgent cardioversion was required due to
severe hypotension. His course was complicated by acute tubular
necrosis. Despite repeat loading with intravenous amiodarone
1.2 g daily for one week, he continued to have frequent
paroxysms of VT.
A cardiac electrophysiological study was performed under
general anaesthesia via the right femoral vein. A quadripolar
catheter was placed in the right ventricular apex. A Preface
trans-septal sheath (Biosense Webster, Diamond Bar, CA) and
a trans-septal needle (Bard Electrophysiology, Lowell, MA)
were used to perform a trans-septal puncture. A 15–25 variable
loop lasso catheter (Biosense Webster, Diamond Bar, CA) and
the Ensite 3-D mapping system (St Jude Medical, Inc, St Paul,
MN) were used to generate a map of the left ventricle. The lasso
catheter and the Preface sheath were subsequently withdrawn. A
guidewire was left behind to preserve trans-septal access.
A Lynx
TM
intergraded RF ablation catheter and robotic sheath
(Fig. 2) was robotically guided across the inter-atrial septum
adjacent to the guidewire and through the mitral valve into the
LV. The guidewire was subsequently withdrawn. A detailed
voltage map of the LV was constructed using the Lynx
TM
catheter
(Fig. 3). A large scar was noted on the posterior–inferior aspect
of the mid LV.
Anaesthesia suppressed the salvos of VT so pace mapping
with the robotic ablation catheter was performed within the
scar border zone. Twelve out of 12 pace matches were obtained
for clinical VT on the posterior lateral aspect of the apex.
Mid-diastolic potentials were noted in the sites where 12 out
of 12 pace matches were obtained. Ablation was performed
whenever 12 out of 12 pace matches were obtained. Accelerated
ventricular rhythms identical to clinical VT were frequently
induced during ablation. The procedure was terminated when
accelerated ventricular rhythms were no longer inducible with
RF energy delivery.
Due to poor LV function (ejection fraction 35%), borderline
blood pressure under anaesthesia even in sinus rhythm and recent
acute tubular necrosis, no attempt was made to induce VT either
before or after ablation. Total procedure time was three hours 30
minutes, RF ablation time was 16 minutes and 45 seconds and
fluoroscopy time (Siemens single-plane X-ray at seven frames
per second) was 18 minutes (2 565.1
µ
g/m
2
).
Post-ablation VT was not seen again. Amiodarone 200 mg
daily was continued as maintenance treatment and weaned down
to 100 mg daily after three months. At 21 months’ follow up
the patient is well on amiodarone 50 mg, telmisartan 80 mg,
simvastatin 20 mg, and aspirin 81 mg daily, and metformin 850
mg twice daily. There was no recurrence of VT and complete
resolution of renal function.
Discussion
This case report details the first successful RF ablation of a
ventricular arrhythmia using a novel flexible robotic technology.
The Lynx
TM
catheter is a 12-French compatible integrated robotic
sheath and open irrigated RF ablation catheter. The ablation
catheter has seven irrigation holes and a flat tip. Previous
robotic VT ablations have been performed using the 14-French
compatible Artisan sheath (Fig. 2).
The reduced profile of the Lynx
TM
catheter enhances its
flexibility and safety. This has significant advantages for the
trans-septal and trans-mitral crossing and has the potential to
reduce groin-related complications. Having completed more
than 100 ablations with this catheter (mostly left atrial ablations),
we have also found the set up time of the Lynx
TM
robotic
catheter to be significantly reduced since the ablation catheter
is integrated into the robotic sheath, and the purging process has
been simplified when compared to the Artisan sheath.
We believe that the outcome of this procedure was favourably
influenced by the robotic technology and particularly the new
Lynx
TM
catheter. The smaller profile and enhanced flexibility was
of particular relevance in this case since the patient was elderly,
ablation was required in the apex of the LV, and the relevant site
was targeted using the trans-septal and trans-mitral approach.
The enhanced catheter stability provided by the robotic sheath
and the capacity to continuously measure contact via IntelliSense
Fine Force technology also most likely improved the efficiency
of both mapping and ablation.
IntelliSense Fine Force technology uses contact-induced
interference with catheter movement as a surrogate measure of
Fig. 3. Posterior view of the Ensite 3-D voltage map with
ablation sites on the scar border zone in the apex of the
left ventricle.
Fig. 2. The Hansen robotic system with Artisan sheath
and Lynx catheter (integrated robotic sheath and RF abla-
tion catheter).
Artisan
Physician workstation, remote catheter
manipulator and robotic sheath
Lynx
Lynx
