CASE IMAGE
A 80-year-old woman with chronic atrial fibrillation on long-term anticoagulation was diagnosed with normal pressure hydrocephalus and referred for ventriculoperitoneal shunt placement. Due to heightened bleeding (HAS-BLED score=4) and stroke (CHA2DS2-VASc score=4) risks, left atrial appendage occlusion with Watchman device was recommended prior to neurosurgical intervention.
Baseline transesophageal echocardiography (Panel A-D ) demonstrated a left atrial septal pouch (ASP), formed by two distinct parallel inter-atrial septal layers, creating a tunnel-like inter-atrial chamber that communicated with the left atrium (LA; broken line) and which contained a thrombus (arrowhead) within its cavity (Video-1; asterix marks mouth of the ASP; RA, right atrium) . Recognizing this, a SENTINELTMcerebral embolic protection device was placed prior to transseptal puncture. A slight shift in thrombus position was noted during septal tenting (Panel E ) and, unfortunately, transseptal puncture resulted in thrombus extrusion from the tunnel into the left atrium before embolizing systemically (Panel F-H; Video-2 ). Following the Watchman device placement, assessment of the ASP showed development of spontaneous echo-contrast (yellow star) within the pouch cavity despite the newly created left-to-right shunt at the transseptal puncture site (Panel I ). A decision was made to obliterate the body of the ASP cavity to prevent future thrombus formation, utilizing a Cardioform septal occluder (Panel J-K ). The remainder of post-procedural course was uncomplicated. No thrombus was identified on examination of the SENTINELTM device post-procedure. Intraprocedural cerebral angiography performed at case conclusion was also negative for intracranial embolism (Panel L ). The patient was admitted overnight for observation and was discharged home the next day without clinical evidence of systemic embolization.
Atrial septal pouch is a common anatomic variant of the interatrial septum and a nidus for thrombus formation, which may be associated with thromboembolic complications.1 Left-sided atrial septal pouch has been associated with an increased risk of cryptogenic stroke.2 Left-sided atrial septal pouch thrombus should be considered a relative contraindication to transseptal puncture. This case highlights the importance of a thorough echocardiographic evaluation of the atrial septum prior to transseptal access and recognition of this anatomic septal variant as a potential cardiac source of embolism.