Title: Combined Endocardial and Epicardial Ablation of Drug-Refractory
Ventricular Tachycardia by Direct Ventricular Puncture
Authors: Hasan Ashraf, MD, Nareg Minaskeian MD, Kristen Sell-Dotin, MD,
Hicham Z El Masry, MD FHRS.
Affiliations: Mayo Clinic, 5777 East Mayo Boulevard, Phoenix, AZ 85054.
Corresponding Author: Nareg Minaskeian, MD. Email address:
nminask@gmail.com. Address: Mayo
Clinic, 5777 East Mayo Boulevard, Phoenix, AZ 85054.
Funding: None.
Disclosure Statement: No disclosures for any authors.
Declarations and Conflicts of Interest: None.
Abstract
Mechanical valves in both aortic and mitral positions pose a challenge
for left ventricular (LV) access during ventricular tachycardia (VT)
ablation using the antegrade transseptal or the retrograde transaortic
approach. A 57 year-old male with ischemic cardiomyopathy, mechanical
aortic and mitral valves, and recurrent VT underwent a combined
endocardial and epicardial ablation via direct ventricular puncture via
mini-thoracotomy. Successful mapping with endocardial and epicardial
ablation was performed, with no recurrent VT on follow up. We showcase
the feasibility of VT ablation using an open transapical approach for
patients with mechanical aortic and mitral valves.
Key Words:
Ventricular tachycardia, epicardial and endocardial ablation, mechanical
aortic and mitral valves, thoracotomy.
Introduction
Mechanical heart valves in both aortic and mitral positions pose a
significant challenge for left ventricular (LV) access during
ventricular tachycardia (VT) ablation using the standard antegrade
transseptal or the retrograde transaortic approach. The customary
approaches are not possible because of risk of catheter entrapment and
death, and alternative strategies are necessary. We describe a variation
of the transapical LV access via direct surgical visualization in which
we successfully utilized both endocardial and epicardial ablation in a
patient with drug-refractory VT.
Case Report
A 57 year-old male with ischemic cardiomyopathy [left ventricular
ejection fraction (LVEF) 25%] and recurrent episodes of VT was
evaluated by the heart rhythm team. He has a complex past medical
history, including Hodgkin’s lymphoma during childhood treated with
chest radiation leading to early development of coronary artery disease
and inferior myocardial infarction treated with proximal RCA stenting at
the age of 36. He eventually developed worsening coronary artery disease
and underwent triple vessel coronary artery bypass surgery two years
later. Following that, he developed calcific valvular heart disease and
severe cardiomyopathy and underwent mechanical mitral and aortic valve
replacement (2011) then a dual-chamber implantable
cardioverter-defibrillator (ICD) implantation for primary prevention in
2012. On follow-up, he developed recurrent episodes of VT appropriately
treated with ICD shocks, which proved refractory to antiarrhythmic
therapy including sotalol, mexiletine, and amiodarone.
After multidisciplinary consultation, he was deemed not a candidate for
heart transplant due to hostile chest and a porcelain aorta, nor a
candidate for standard approach of endocardial ablation due to
mechanical mitral and aortic valves. We initially attempted an
epicardial ablation using a subxiphoid approach however significant
amounts of adhesions prevented advancement of the guidewire in the
pericardium. We also attempted trans-interventricular septal access but
despite successful access to the LV, we were unable to advance the
sheath through a hypertrophied septum and the procedure was aborted at
that point.
The patient continued to worsen clinically with frequent episodes of VT
and ICD shocks despite titrating his oral amiodarone dose to 400 mg
twice daily. One last attempt at ablation was planned using a combined
transapical endocardial and epicardial approach. The procedure was
performed under general anesthesia with transesophageal
echocardiographic (TEE) visualization of the heart. Standard femoral
venous access was obtained, including a 6-Fr deflectable quadripolar
catheter which was placed in the right ventricle and a 10-Fr Carto
(Biosense Webster Inc., Irvine CA) Sound intracardiac echocardiography
probe in the right heart. Subsequently, a mini-left thoracotomy was
performed using a 6 cm incision along the 5thintercostal space, exposing the cardiac apex. The pericardium was opened
using electrocautery and careful dissection was performed to take down
the pericardial adhesions. The LV apex was identified and an appropriate
cannulation site, around the inferolateral apex, was confirmed with TEE
guidance. Two 3-0 Ethibond pledgeted sutures were used to create
pursestrings on the LV apex, and the apex was accessed under direction
visualization with a cook needle and wire. The tract was dilated, and a
standard 9-Fr Cordis sheath was inserted into the access site, through
which an 8 Fr irrigated bidirectional ThermoCool (Biosense Webster Inc.,
Irvine CA) ablation catheter was inserted (Figure 1). Unfractionated
heparin was initiated upon access of the left ventricle and continued
throughout the procedure, with a target activated clotting time of
250-300 seconds.
Electroanatomical mapping was performed using Carto software recording
voltage and marking local abnormal ventricular activations (LAVAs,
Figure 2a). The voltage map revealed a dense inferior wall scar
extending from the apex to the base (Figure 3), and LAVAs were tagged
and concomitantly ablated. Of note, hemodynamically unstable ventricular
tachycardia (cycle length 440 msec, Figure 2b) was induced by catheter
manipulation requiring external cardioversion restoring sinus rhythm and
we were unable to perform mapping and entrainment during VT.
After completion of endocardial ablation from the transapical site,
attention was turned to the epicardium, particularly the apex which was
incompletely mapped and ablated endocardially around the sheath entry
site due to technical difficulty. An Articure cryoablation probe was
used to apply linear lesions along the entire apex, including inferior,
lateral, and septal segments. Endpoints were assessed with an aggressive
programmed ventricular stimulation protocol using a drive train of 600
msec with up to 3 extrastimuli to ventricular refractoriness. No
sustained ventricular arrhythmias were inducible, and this was deemed a
successful procedural endpoint.
He was transferred to the intensive care unit and progressed well
post-operatively without any complications. Oral warfarin with a heparin
bridge was initiated the same night of the procedure. He was extubated
the following day, and discharged two days later without antiarrhythmic
medication. On 2-month follow up, he remains physically active and
device interrogation revealed no ventricular arrhythmias.
Discussion
Patients with drug-refractory VT and double mechanical valve prostheses
presents a unique challenge in that conventional percutaneous LV access
via antegrade transseptal or reotreograde aortic approach is not
possible (no-entry LV). A number of these VTs can be ablated from the
right ventricle, such as with bundle branch reentry, or with epicardial
access.1 However, patients with surgically implanted
prostheses may have pericardial adhesions that preclude epicardial
ablation. Additionally, the epicardial approach may not be optimal given
the endocardial location of reentrant circuits, which occurs commonly in
ischemic cardiomyopathies, which may decrease the efficacy of isolated
epicardial ablations that do not extend deep enough to the endocardial
surface to alter the arrhythmogenic substrate.
Alternative approaches to these challenging patients have been
described, including transcoronary ethanol ablation, surgical
cryoablation, percutaneous trans-right atrial access to the LV through
the creation of an iatrogenic Gerbode defect at the inferior-septal
process of the LV, and interventricular septal puncture.2-6 However, these approaches are technically
challenging and success is highly dependent on specific anatomy that can
vary considerably between patients. The use of radiation therapy has
been also used for VT ablation but long term follow up is limited and
complications are not insignificant.7 This case
demonstrates the major advantages of an open surgical approach which
includes the ability to deliver both endocardial and epicardial lesions,
significantly increasing the chance of success. An additional advantage
is the theoretical feasibility for most LV VTs, as the apical approach
would allow for easy catheter maneuverability and access of most of the
LV. Using a deflectable ablation catheter, we were able to access most
of the LV with minimal difficulty even without a deflectable sheath,
except for the location in immediate proximity of the catheter access
site. Because the LV apex is easily accessible with a minithoracotomy
and is thinner in most patients compared to other more basal LV walls,
it provides an ideal anatomy for epicardial cryoablation. This permits
transmural application of ablative lesions for substrate modification,
and thus increases chance of success as demonstrated in our patient.
A prior case series that utilized both percutaneous transapical LV
access as well as surgical access noted a significant drawback with
surgical access because of weak tissue support from the LV myocardium
which could lead to sheath dislodgement.8 This is
indeed a possibility, though in our case we stabilized the sheath
manually throughout the case, rendering the risk of sheath dislodgement
negligible. Although this may be cumbersome, we believe that this is far
outweighed by the risks and high incidence of adverse outcomes of a
percutaneous approach.
The major drawback of a more invasive approach is mitigated by the
relative technical straightforwardness of the procedure, its general
applicability to most LV VTs, the high likelihood of success, and the
low incidence of complications. Although experience is limited in these
complex ablations, prior cases have suggested that most risks with
transapical approaches are due to the percutaneous approach rather than
the surgical one. A mini-thoracotomy approach would also permit better
control of hemostasis and fewer complications, and is not necessarily
associated with a lengthier hospital stay. Concerns with the surgical
approach include holding anticoagulation for mechanical valves, though
this can be accomplished with just a few hours if adequate bridging is
accomplished, and with newer less thrombogenic mechanical valves, the
concern for thromboembolism is significantly diminished. Additionally,
we demonstrated that with careful selection of patients and with
utilization of good surgical technique, speedy discharge within a few
days is feasible. Though further data is undeniably needed regarding
long-term outcomes and comparative outcomes between different strategies
for VT ablation, this case adds to the growing literature regarding the
relative technical ease, feasibility, excellent complication profile,
and efficacy of this approach.
Figure 1