Keywords thrombectomy - neuroprotection - patent foramen ovale
Introduction
Cerebral embolic stroke is a potentially devastating complication in patients with
patent foramen ovale (PFO). The risk of stroke is amplified in the setting of venous
thromboembolism (VTE), particularly clots in transit or presence of right atrial thrombus
that requires intervention to curtail potential paradoxical embolism. Cerebral embolic
stroke is also a well-known potential complication of transcatheter aortic valve repair
(TAVR).[1 ] During TAVR, atherosclerotic plaque, debris, or calcified valve remnants may fragment
and embolize into the cerebral vasculature causing stroke. To mitigate the risk of
stroke during TAVR, cerebral neuroprotection devices for debris capture may be used.
In this case report, we describe successful implementation of the Sentinel cerebral
protection system (Boston Scientific, Marlborough, Massachusetts, United States) for
neuroprotection from paradoxical embolus during right atrial endovascular aspiration
thrombectomy and PFO closure.
Case Report
A 41-year-old female with a history of breast cancer status post bilateral mastectomy
and radiation therapy with a recently placed right indwelling Port-A-Cath presented
with sudden onset arm swelling. A computed tomography angiogram was performed on her
right arm and chest, showing no evidence of vascular stenosis but revealing a 3.6
cm right atrial clot at the catheter tip. After 3 months of therapeutic anticoagulation,
it was noted on transesophageal echocardiography (TEE) that her right atrial thrombus
was still present and that there was also a previously unidentified PFO, with a bidirectional
shunt across the atrial septum seen with contrast ultrasound. Given her extensive
surgical history and comorbidities relating to her breast cancer treatment regimen,
a minimally invasive strategy was pursued. A multidisciplinary discussion between
interventional radiologists, cardiothoracic surgeons, and cardiologists was made to
proceed with minimally invasive clot retrieval following PFO closure to minimize the
risk for embolization event and allow Port-A-Cath removal.
The patient was brought to the angiography suite under general anesthesia where the
intraoperative TEE demonstrated a mobile thrombus extending from the Port-A-Cath tip
to the free wall of the right atrium as well as the PFO ([Fig. 1A ] and ►1B). Traditionally, the PFO would be closed prior to clot retrieval given concern for
paradoxical embolus and distal thrombus migration into the pulmonary circulation.
However, due to the size of the right atrial thrombus and the catheter manipulation
required to place the closure device, the Sentinel percutaneous cerebral protection
device (Boston Scientific, Marlborough, Massachusetts, United States) was utilized.
Fig. 1 Transesophageal echocardiography demonstrating (A ) cross-section of a hyperechoic mobile thrombus (yellow arrowhead) abutting the free
wall of the right atrium and patent foramen ovale (yellow arrow) with (B ) corresponding Doppler flow present.
The right radial artery was accessed under ultrasound guidance and a slim 5F sheath
was placed followed by intraarterial infusion of heparin and nitroglycerin. The articulating
sheath located in the distal end of the cerebral protection device was then rotated
until the tip entered the ostium of the left common carotid artery. Tension was provided
to the articulating sheath such that the curvature conformed to the brachiocephalic
artery—aorta-left common carotid artery junction and pulled toward the carina between
the two vessels. The proximal filter was then deployed in the brachiocephalic artery
under fluoroscopic guidance to confirm filter to vessel-wall apposition ([Fig. 2A ]). In this configuration, the carotid basket was subsequently deployed without complication
([Fig. 2B ]).
Fig. 2 (A ) Proximal filter (yellow arrow) of the Sentinel system being deployed within the
brachiocephalic artery over a Balance Middle Weight (BMW) wire. (B ) An articulating sheath located in the distal end of the Sentinel system was advanced
and rotated such that the tip could insert into the origin of the left common carotid
artery. Tension was provided so that the curvature of the system was aligned with
the brachiocephalic artery—aorta-left common carotid artery junction and pulled toward
the carina between the two vessels. The left common carotid artery was then deployed
(yellow arrow).
From the right common femoral vein, a multipurpose catheter and 035 Glidewire were
then used to cross the PFO into the left atrium, followed by exchange for an Amplatz
extra-stiff wire that was placed into the left upper lobe pulmonary vein. A 9 Fr Torque
view sheath was advanced across the PFO under TEE visualization. Under fluoroscopic
and echocardiographic guidance, a 35 mm Amplatzer PFO occluder (Abbot Inc, Minneapolis,
Minnesota, United States) was deployed, with particular attention to avoid the existing
large right atrial thrombus. Agitated saline injection demonstrated shunting of bubbles
across the PFO at baseline was resolved following occlusion device placement and release.
The Sentinel device was then withdrawn. Upon visual inspection, the Sentinel device
filters contained several embolic fragments in both innominate and left common carotid
artery baskets ([Fig. 3 ]).
Fig. 3 Fibrous appearing chronic embolic fragments were noted in the Sentinel system filters,
with a larger amount in the left common carotid basket.
With the PFO occlusion device in place, attention was turned to the right atrium to
guide removal of the right atrial thrombus under fluoroscopic and TEE guidance. Left
common femoral venous access was obtained under ultrasound guidance with subsequent
insertion of an 18 Fr Fem-Flex reperfusion catheter advanced into the left common
iliac vein. The patient was then systemically heparinized to a target activated clotting
time of 300 seconds. The venovenous bypass circuit was de-aired and brought sterile
to the field. Under combination of fluoroscopic and TEE guidance, the AngioVac aspiration
cannula (AngioDynamics, Latham, New York, United States) was advanced into the right
atrium directly against the mass, where moderate volumes of thrombus were aspirated
([Fig. 4 ]). On TEE, it was noted that there was residual thrombus noted abutting the free
wall of the right atrium. However, no further intervention was pursued at this point
due to the residual thrombus being located in proximity to the recently placed PFO
closure device. After the AngioVac cannulas were removed, the port was able to be
removed without complication. The postprocedure course was uneventful without evidence
of neurological symptoms. While there is also a possibility of embolic material traveling
distally to abdominal organs or extremities, there was no indication of critical limb
ischemia or visceral organ infarct noted in this case. The patient subsequently discharged
home after the procedure on apixaban 5 mg twice daily. Follow-up transthoracic echo
after 6 weeks failed to identify any significant residual right atrial thrombus.
Fig. 4 Transesophageal echocardiography transducer guiding AngioVac aspiration device (yellow
arrow) around the right atrial thrombus from femoral access after neuroprotection
device had been deployed. The 35 mm closure device (yellow arrowhead) was placed prior
to manipulation of the right atrial thrombus.
Discussion
Cerebral embolic stroke is a feared complication in patients undergoing aortic arch
endovascular interventions.[1 ] Apart from major stroke, microvascular “silent” infarcts are seen in approximately
70% or more of patients on postprocedure diffusion-weighted magnetic resonance imaging.[2 ] To mitigate the risk of cerebrovascular embolization of plaque or calcified valve
materials during TAVR, cerebral embolic protection devices are employed as an intraprocedural
neuroprotective strategy. Our patient had a large thrombus in the right atrium with
a theoretical risk of dislodgement through the PFO of similar size and into the cerebrovascular
circulation. PFO closure alone without neuroprotection was thought to be of higher
risk due the catheter manipulation required around a significant thrombus burden.
The Sentinel neuroprotection device was therefore deployed prior to PFO closure and
aspiration thrombectomy. After the procedure, the neuroprotection device was revealed
to have caught multiple embolic fragments, validating the decision for stroke prevention.
Central venous catheter tip-associated thrombus is a commonly encountered scenario
without clear evidence-based guidelines. The etiology of catheter-related thrombus
is unknown but hypothesized to be related to mechanical irritation of the right atrial
free wall or flow disruption leading to activation of coagulation pathway.[3 ] A recent study demonstrated that out of 49 patients with echocardiogram-detected
catheter-tip associated thrombus, no embolic or other complications were seen, suggesting
that aggressive interventions may be unnecessary.[4 ] In contradistinction, other groups have tried to mitigate the risk for pulmonary
emboli or hemodynamic compromise by successfully reducing the clot burden with anticoagulation.[5 ] Since our patient failed anticoagulation management, we chose to take a minimally
invasive approach by removing the thrombus via a catheter-directed approach even after
the PFO was closed, eliminating the risk of additional thrombus formation and potential
dislodgement.
The Sentinel embolic protection device utilized in this study is a filter device designed
to capture debris dislodged during TAVR, as seen in our case study. The Sentinel trial,
the largest randomized clinical trial evaluating the safety and efficacy of this protection
device, showed a significant reduction in median new diffusion restricting lesion
volume in the protected territories up to 1-week after TAVR.[6 ] Furthermore, histopathological debris was found in the filters in 99% of the patients.[6 ] A recent meta-analysis of five randomized clinical trials of 625 patients, using
death or stroke as the composite endpoint, found that neuroprotective devices reduced
absolute risk (ARR) of events by 3.5% for a number-needed-to-treat (NNT) value of
approximately 28.[7 ] However, these studies largely evaluated stroke events in the short-term time frame
and its use of a composite endpoint has been questioned.[8 ] A subsequent propensity matched analysis of 560 patients utilizing dual-filter protection
devices during TAVR demonstrated significant decrease in disabling and nondisabling
stroke from 4.6 to 1.4% with ARR of 3.2% and NNT of 31 (p = 0.03, odds ratio = 0.29, 95% confidence interval: 0.10–0.93).[9 ]
This case demonstrates successful neuroprotection in a patient with a PFO and large
right atrial thrombus prior to PFO closure and aspiration thrombectomy, with the use
of the Sentinel neuroprotection device. The presence of macroscopic embolic fragments
in the filter baskets highlights the role of prophylactic embolic protection when
performing cardiac interventions in the setting of a PFO and elevated VTE risk, especially
right atrial thrombus or mass.
