Hybrid Procedure:
The hybrid convergent procedure has been previously described in
detail.3,5,6 To briefly summarize our surgical
experience, preoperative evaluation included an echocardiogram and an
ischemic evaluation. General anesthesia was used for all cases.
Initially, a laparoscopic approach with an upper midline abdominal
incision and the placement of a single incision laparoscopic surgery
(SILS) Port was used. Insufflation and two working ports (including a
grasper and a harmonic scalpel via the SILS port) allowed us to gain
access into the pericardial space via the bare area of diaphragm just
medial to the falciform ligament, above the left lobe of the liver.
After a year or so, our approach changed. We were able to perform a
similar subxiphoid incision without laparoscopy (saving time and cost)
by packing the stomach and omentum off to the patient’s left with a
moist sponge and using two appendiceal retractors to expose the bare
area of the diaphragm. A long-tipped low-power Bovie was used to divide
the diaphragm and access the pericardial space.
Once access was obtained with the cannula and laparoscope, the ablation
was carried out beginning at the pericardial reflection against the
medial side of the right superior pulmonary vein (PV). We moved from
superior to inferior along the left atrium (LA), medial to the right PV
and down to the level of the inferior vena cava (IVC). This movement was
repeated on the patient’s left. We ablated to the coronary sinus, taking
care to overlap lesions. We then moved underneath the left inferior PV
and attempted ablation on the left anterior portion of the left PVs. In
approximately two-thirds of cases, we could observe catheter placement
up to the base of the left atrial appendage (LAA). In one-third of
cases, we could not see the anterior portion of the left PVs due to
hemodynamic instability. For these cases, we would place three or four
lesions blindly.
After left anterior PV ablation, we ablated the anterior portion of the
right PVs. With each ablation, we instilled 25 cc of room-temperature
saline into the pericardial wall through the cannula to avoid thermal
conduction to other mediastinal structures. Once finished, we placed a
silastic drain through a separate incision. We infused 500 mg of
solumedrol through the drain and let it sit while we closed the incision
in a standard manner. The drain was hooked to bulb suction and removed
on the day of discharge. After the surgeon completed the epicardial
ablation, all chest incisions and drains were covered in a sterile
fashion. Then, the endocardial evaluation and intervention by the
electrophysiologist commenced.
After baseline intervals and pacing thresholds were measured, RA and RV
pacing at fixed incremental cycle lengths were performed. The first half
of the initial heparin bolus was then given, and the maintenance
infusion was started after the diagnostic catheters were in position.
The cryoballoon (CB) process of PV isolation began after transvenous
access and transeptal puncture. At that point, an exchange length wire
was advanced to the left superior PV to exchange for a 12F FlexCath
sheath in place of a SL-1 sheath. The second half of the heparin bolus
was given after the left atrium was entered. A preoperative computed
tomography scan with contrast of the LA and PVs was used to evaluate LA
size, PV anatomy (including any anomalies), and the PV ostium. Depending
on the size of the ostium, a 23/28mm Artic Front CB catheter with a
spiral 15/20mm Achieve wire was advanced sequentially to all PVs, the
anterior and posterior walls of the LA, and the roof of the LA. Using a
field filter of 0.1 mV, each area was mapped to evaluate for isolation.
Pacing, using the Achieve catheter, was performed to verify non-capture
at the antrum/ostium of each PV as well as the posterior wall. Entrance
and exit block were confirmed in all pulmonary veins. A 3D anatomical
map was performed of the LA (specifically the roof), posterior walls,
and all PVs. This was done to verify PV and posterior wall isolation.
Posterior wall isolation was homogenous, starting at the level of the
superior PVs down to the level of the right and left inferior PVs.
It was generally identified that the anterior/superior turnaround
borders of the left and right superior PVs were not completely isolated,
especially the ridge between the left superior PV and the LAA. Rarely,
the inferior/posterior borders of the left and right inferior PV were
also still connected. When the PVs were not completely isolated,
cryo-energy was delivered to complete the isolation. Care was taken to
verify that the esophageal temperature probe was positioned directly
behind the PV we were isolating or the posterior wall we were ablating.
The goal was to achieve approximately -40 degrees Celsius for 4 minutes.
When PV signals were present on the Achieve catheter, we strove to
isolate these signals or eliminate them altogether within the first 60
seconds. If this was not achieved, we would reposition the balloon
catheter to find a better fit and seal. Care was taken to verify that
the esophageal temperature did not fall below -30 degrees Celsius.
When delivering cryo-energy along the right-sided PVs, a quadripolar
catheter was often positioned in the right subclavian vein to pace the
right phrenic nerve. A fetal monitor was placed on the patient’s abdomen
to audibly monitor right hemidiaphragm contractility. Cryo-energy
delivery to the right-sided pulmonary veins was stopped when the
intensity of diaphragmatic contractility began to diminish. When the
endocardial posterior roof line was not complete, a 4 mm tipped
deflectable, irrigated tipped electrode was used to deliver
radiofrequency using 20-25 watts for 30-60 seconds. If the esophageal
temperature probe temperature rose > 1 degree Celsius,
ablation was stopped, and the area was allowed to return to baseline
temperature before another ablation lesion was delivered nearby, but not
in the same location. The goal was elimination of endocardial signals
> 0.1 mV and lack of pacing response from the ablated area.
When all PVs and the posterior wall were isolated and the posterior
roofline was completed, we would continue to pace and remap for 20
minutes after the last ablation. Isoproterenol up to 5 mcg/min was often
infused during this waiting period. Sometimes intravenous adenosine 6
and 12 mg were used after the 20-minute waiting period. If there was no
reconnection of PVs or posterior wall, then the ablation was terminated.
Post ablation, no significant signals above 0.1 mV were observed.
Likewise, pacing along the line failed to capture atrial tissue. After
PVI, RA, and RV incremental pacing and programmed stimulation were
performed. No arrhythmias were inducible. Intracardiac echocardiography
was used to rule out pericardial effusion as well as to measure PV
velocities pre- and post-procedure. Heparin was reversed with
intravenous protamine by the anesthesia service.