Abstract ;
Ultrasound guided venous access is important to minimize pneumothorax
and unnecessary incisions in patients undergoing device implant.
Ultrasound (US)-guided vascular access has become the standard-of-care
for intravascular procedures at many institutions. This trend is owed to
reduced vascular access site complications, increased first-pass
success, and reduced access time [1]. Nevertheless, the adoption of
US in cardiac electronic device implantation has lagged– likely bound
by inertia rather than a technical challenge.
The Agency of Healthcare Research and Quality (AHRQ) has developed a set
of administrative-data-based Patient Safety Indicators (PSIs) to
identify in-hospital patient safety events [2]. Conferring excess
morbidity, length of stay, and health care cost, iatrogenic pneumothorax
is identified as a PSI and occurs in approximately 1-2% of device
implantations [3, 4]. Operator experience, safe technique, and
ultrasound use during central venous access can prevent iatrogenic
pneumothorax [5]. Thus, in an utopic world , a pneumothorax is
seldom forgivable, rarely excusable, and always unacceptable.
Reducing access-related vascular complications has also become
especially important in an era where uninterrupted periprocedural
systemic anticoagulation has become the default for most patients
[6]. There is also a widespread push towards reducing the use of
fluoroscopy and intravenous contrast when possible. Conventional methods
including anatomic, fluoroscopy, and contrast venography guided venous
access are often still taught as the standard. These approaches remain
popular, perhaps due to operators’ reluctance to adopt a new technique
in the absence of a randomized trial to support a substantial benefit.
Chandler et al. [7] present their retrospective experience of
US-guided access for transvenous device implantation from a single
center. This study’s results are significant, showing a 95% success
rate with US guidance regardless of laterality. Compared to an age- and
sex-matched cohort undergoing conventional axillary/subclavian vein
access by operators at the same institution, the US’s use was associated
with reduced fluoroscopy times and similar median procedure times. A
small number of complications were reported in both arms, and there were
three pneumothoraces in the conventional arm as opposed to 0 in the US
arm.
A notable observation in this study was avoiding an unnecessary skin
incision in two patients where US before incision revealed a need to
convert to the contralateral side. This highlights the benefit of
US-guided access before skin incision that has not been apparent from
many prior publications. Although the authors mention that some
operators may be hesitant to perform percutaneous needle puncture out of
concern for increased infection brought about by the introduction of
skin flora into the pocket, an association has not been reported in the
existing literature, and the US arm of this study did not report any
device infections.
A significant limitation to note in the current study and several others
[8-12] is the reliance on data gathered from one or two operators
with experience in ultrasound-guided axillary vein access. It does not
account for the learning curve, which would be encountered by new
adopters. Studies have shown that operators can reduce implant time
after trying in 15-25 patients [9,12], but prospective data are
needed to show how inexperience might influence outcomes.
The current study utilized a wireless US system with a wide probe, which
made placing the probe inside a small incision impractical. Therefore,
the primary reason for failure was vessel depth beyond the reach of a
percutaneously inserted 4F micropuncture needle, and body habitus likely
played a role in these patients. Using longer micropuncture needles or
smaller wired probes inside a sterile sheath within the pocket following
incision, the operator could further expand eligibility for US-guided
access. This latter approach may not avoid unnecessary incisions, but
the other benefits, including reduced fluoroscopy and contrast
utilization, should remain.
This study otherwise adds to prior observational data suggesting that
when compared to fluoroscopy-based axillary/subclavian vein access
techniques, US guidance is safe and successful in >90% of
patients with a trend towards reduced fluoroscopy use and no impact on
total implant time [8-10].
Although several studies have suggested a little-to-no downside to using
the US for access, observational data limitations make it challenging to
conclude the US’s superiority over conventional methods for
complications such as pneumothorax or hematoma. A prospective randomized
study powered to detect differences in these outcomes would ultimately
put this question to rest. However, the question remains if is it
possible or even needed?
Furthermore, the current study emphasizes another potential benefit of
initial percutaneous US imaging in avoiding unnecessary skin incision.
With the wide availability of ultrasound and a trend towards reduced
fluoroscopy times, even a small absolute risk reduction would drive a
widespread practice change
Vascular access techniques such as the “blind stick” are frowned upon
in many interventional specialties. If not already in place, we
anticipate that ultrasound will become standard equipment in most
cardiac device labs. When more sophisticated methods are safer and
widely available, clutching to the convention may not be wise even in
the absence of a clinical trial. US-guided vascular access is a skill
that the device implanter should have in the armamentarium.