Page 299 - Read Online

Page 12 of 18 Zimmermann et al. Vessel Plus 2019;3:31 I http://dx.doi.org/10.20517/2574-1209.2019.010

which first addresses underlying pulmonary hypertension [123] . Optimization of elderly patients with
concomitant pulmonary hypertension prior to ASD closure remains an area of active research.

Cardiac erosion after percutaneous ASD intervention
In patients with superoanterior rim deficiency, the increased risk of serious complication, i.e., “cardiac
erosion” may increase after implantation of the device. The exact mechanism of “cardiac erosion” is not
been well understood; previous clinical experience proposed that an aortic rim deficiency and oversized
occlusion device may be highly correlated with cardiac erosion [124] . In response, updated instructions-
to-user were published for the Amplatzer device with specific guidance for aorto-superior rim size
specifications [125] . One recent case series reported that absence of the aortic rim was common finding
among patients who developed erosion [126] . Subsequently, other putative risk factors were also reported as
physicians modified their practices and over sizing became less common [127] . Specifically, deficient aortic
or SVC rim size, along with balloon sizing were associated with increased risk of erosion [128] . It should be
noted, however, that these studies are retrospective in nature, and prospective studies have not yet been
undertaken to determine true causal relationships for erosion relating to rim size.

FUTURE DIRECTION OF TRANSCATHETER INTERVENTION FOR ASD
The transcatheter ASD repair has evolved from employment in select patients unable to undergo open
surgical repair, to applications in pediatric populations, and is now gaining traction in the elderly. Where
currently secundum type ASDs and limited case-reports of closure in other varients of ASD are now being
reported, we may expect future devices to address these limitations. On the other hand, complications
arising from this procedure, especially cardiac erosion, are still being reported. Progress over the last
several decades in terms of safety and efficacy are impressive and point to a bright future in the treatment
of congenital heart defects. We conclude this review by looking to the near and long-term future in the
state of the field.

New devices for difficult ASD closure
Several technical modifications have been introduced over the years to address difficult transcatheter ASD
closure, including delivery sheath modification, position deployment, or additional material to hold the left
atrial disk inside the LA. Some advocate deployment with balloon assisted placement [129] . This technique,
however, may cause injury to the pulmonary vein. The development of steerable catheters may offer
improved techniques in positioning ASD devices [130] . Use of such a steerable catheter has been described in
case reports, but has not yet been implemented in commercially available devices, offering an opportunity
for future development [131] .

Endovascular retrieval of embolized devices
A well described early and mid-term complication of transcatheter ASD closure is device dislodgement
and embolization. The rote response, if the device has been fully deployed, is to convert to open surgery
for retrieval and repair. Improving techniques for endovascular retrieval are supported by case reports,
case series, and retrospective reviews of experience [132-134] . Common embolization sites are the left ventricle,
abdominal aorta and femoral vessels [135,136] . Lastly, Martins, Mendez, and Anjos provide an excellent
pictorial stepwise description of various retrieval techniques and devices, and even include demonstrative
videos [137] . Protective devices to prevent embolization during surgery may be an area of future interest to
prevent distal embolization periprocedurally [138] .

Salvage of residual shunt with device-in-device intervention
Intracardiac devices that are malfunctioning, whether dislodged, malpositioned, or sub-optimally effective,
are typically treated with open heart surgery for removal and remedy. At the present, there are only case
reports describing “device-in-device” salvage to return function to such malfunctioning devices [75,139] . The