Case Report:
A 50-year-old male with LMNA cardiomyopathy and NYHA class III and left
ventricular ejection fraction (LVEF) of 35% was admitted with
electrical storm. His initial presentation was atrial fibrillation in
2007, left bundle branch block and cardia arrest in 2017, following
which cardiomyopathy diagnosed and extensive work up including genetic
testing revealed that he was haplo-insufficient for LMNA due to a
microdeletion of chromosome 1. 7 He underwent
placement of a secondary prevention defibrillator/cardiac
re-synchronization therapy (CRT-D) following cardiac arrest and
recovery. Despite optimal medical therapy and resynchronization therapy,
his LVEF continued to decline, and he developed frequent episodes of
ventricular tachycardia (VT). One month before admission, he underwent
catheter ablation with substrate modification at the peri-aortic area of
the left ventricle but continued to have uncontrolled arrhythmia. At
that time, Computed tomography of the heart did not suggest myocardial
replacement fibrosis, but the images were limited by intracardiac device
artifact.
After catheter ablation, arrhythmia was managed with Amiodarone 400mg a
day and Metoprolol 200mg a day but continued to have high burden of
self-limited but symptomatic slow VT. Three weeks later, he suffered
frequent prolonged episodes of slow VT with CL of 460ms below the rate
of detection in the device’s slowest therapy zone (420ms). Beside
palpitations, he was hemodynamically stable and presented to outpatient
clinic. After immediate transferred to the emergency room, a successful
manual anti-tachycardia pacing (ATP) converted his rhythm to sinus
rhythm. He was referred to the electrophysiology laboratory for mapping
and CA of electrical storm.
Procedure description:
The procedure was performed under conscious sedation then changed to
general anesthesia during epicardial mapping and ablation. Two catheters
were used for the purpose of mapping and ablating: multipolar mapping
catheter (PentaRay®) and 3.5-mm tip irrigated catheter
(Thermocool SMART-TOUCH; Biosense Webster). Endocardial/epicardial
voltage maps were created by using a three-dimensional (3D)
electroanatomic mapping system (CARTO, Biosense Webster). Bipolar
electrogram amplitude of <1.5 mV was defined as low- voltage
zone consistent with scar. Dense scar was defined as voltage ≤0.5 mV.
Images integration with the preprocedural contrast-enhanced computer
tomography scans and the 3D mapping system images were used to identify
and reconstruct LV and coronary arteries anatomy. Catheter ablation
sites were chosen based on entrainment, activation, and substrate
mapping.
Initially, trans-septal access was utilized to map the left ventricle
endocardium then changed to retrograde arterial access for further reach
of targeted substrates. During endocardial mapping, extensive
low-voltage substrates were noted at the peri-aortic area with extension
to the sub-aortic/mitral continuity and the peri-mitral valve areas,
with normal endocardial bipolar voltage in the remainder.
Programmed ventricular stimulation from the RV catheter with stimulation
at 600/320 millisecond (ms) induced the clinical VT. We were able to
induce four VT morphologies during the procedure (Figure 1). Entrainment
from the endocardial space at the periaortic area showed concealment and
short stimulation to QRS indicating VT exit site. Despite successful
concealed entrainment at the peri-aortic area, complete tachycardia CL
mapping was not possible during endocardial approach (Figure 2).
Earliest sites of activation during clinical VT were noted to be a wide
area at the anteroseptal wall. See figure 3. Radiofrequency (RF)
ablation lesions were performed at this site. Extensive RF ablation was
performed by targeting all areas of fractionated, late potentials and
long stimulus to QRS sites. In addition, we ablated at the septal
aspect of the right ventricle outflow tract (RVOT) opposing the left
ventricle outflow tract (LVOT) to bracket the targeted area.
Simultaneous endocardial unipolar voltage mapping indicated possible
extensive epicardial scar. See figure 2. After anticoagulation reversal,
epicardial access was obtained using the Needle-in-needle technique.8 A Decapolar catheter (Webster®Decanav) was inserted through a long 8 French sheath to the epicardial
space and used for mapping and pacing purposes. Low voltage areas were
noted anterior to the LVOT with anterior extension toward the apex and
at the basal portion of the lateral wall (Figure 2). Ventricular sites
with fractionation and late potentials were marked during voltage
mapping at the epicardium. Pace mapping was performed to evaluate the
best match with the clinical VT. Coronary artery territory and areas of
phrenic capture were marked. Clinical VT was induced by pacing from the
RV catheter. Despite extensive epicardial activation mapping during VT,
the full CL was not completely mapped. (Figure 3). Best entrainment from
the epicardium was at the LV anterior wall with concealed fusion and
long post-pacing interval indicating bystander site. Multiple RF lesions
were delivered at the epicardial space that demonstrated good
entrainment properties, pace mapping closer to the morphology of
clinical VT, earliest pre-systolic site or sites with the long stem to
QRS period. During ablation we utilized RF power of 50 watts, and half
normal saline to produce deeper lesions at presumed intra-mural
substrate in locations deemed to be safe and > 10mm apart
from the marked coronary arteries. 9 Thereafter,
attempts to re-induce clinical VT have failed and the target VT was
rendered non-inducible. The patient was hemodynamically stable after the
procedure and was transferred back to the cardiology floor. After 48
hours of observation, without significant arrhythmia, he was discharged
home on Amiodarone. He was hospitalized one month later with frequent
ATP and required quinidine treatment which was effective. Both
Amiodarone and Quinidine were slowly weaned off later because of side
effects. Six months since ablation, he has been free of any significant
ventricular arrhythmia or ICD shocks. Because of worsening cardiac
function, he is currently undergoing thorough evaluation for cardiac
transplantation.