BCMS Medical Record Fall 2020 - 22

M e d i c a l R ec o r d F e a t u r e

Measuring the Success of Mitraclip
Technology via Predictive Modeling
bby Paige Cincinnati
Berks County Medical Society 2020 Student Intern
Advisors: Gregory T. Wilson, DO, Cardiology - Tower Health Medical Group,
and Patti J. Brown, MD, Physical Medicine and Rehabilitation Penn State Health St. Joseph

Introduction:

Mitral Regurgitation (MR) is a complication in which the
chambers of the heart cannot properly pump blood from the
left atrium to the left ventricle due to insufficiencies in the valve
function. The mitral valve, which serves as a doorway from the left
atrium to the left ventricle, weakens, preventing the leaflets from
closing tightly enough once the blood has entered the left ventricle.
Due to the valve's inability to close properly, blood gets pushed
back into the left atrium. In other words, that doorway between
the two chambers buckles back like a saloon door and gets stuck,
trapping excess blood in the top chamber. This phenomenon is
commonly referred to as a "leaky valve."
Mitral regurgitation ranges in severity. Some cases, if carefully
controlled with medication, can be left without surgery. These
medications- diuretics, blood-thinner, or high blood pressure
medications-treat the symptoms of MR, not necessarily MR itself
(Mayo Clinic). Therefore, over time the severity of the condition
can increase, leaving patients in need of some form of surgical
treatment. Most commonly, the valve is repaired through a mitral
valve replacement surgery. However, valve replacement is a major
surgery with a long recovery. Its benefits include durability over
time. According to the Cleveland clinic, 95% of patients are free of
operation for 10 years post-operative, and 90% are operation free
20 years after the initial surgery (Cleveland Clinic). Despite its high
success rate, mitral valve replacement surgery carries significant risk
for complications related to its invasiveness and the recovery period
is long. Therefore, less-invasive alternatives were explored to reduce
operation and recovery time.
The Mitraclip, produced by Abbot, served to be this
alternative. This biomedical device was initially approved by the
FDA in 2013. However, the product went through a secondary
approval process in 2014 to expand its range of candidates.
Mitraclip was initially approved to treat patients with mild MR
who would not respond to Cardiac Resynchronization Therapy
(CRT), a specialized pacemaker function (Seifert et al). However,
approved indications for the Mitraclip have since been expanded to
include patients with moderate to severe symptoms (Grasso et al.).
The Mitraclip itself is made of metal for stability and dressed
in polyester to prevent tearing of the tissue during the placement
of the clip. The clip itself is shaped like an alligator's jaw unhinged,
spread wide open, and attached to a metal rod. The rod and the
jaw-shaped fixture are connected via a thin metal string, wound in a

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circle between the two parts (Figure 1.1).
Figure 1.1: The Mitraclip device itself,
size is approximately 4.0cm2
The clip enters the body intravascularly, meaning
the surgeon will thread the clip through the femoral
vein for access to the heart. The surgeon will make
an initial incision to access the femoral vein and
thread a thin, medical-grade wire up to the heart
and puncture the wall of the left atrium. The thread of metal
will act as a guide, similar to a stent-placement or other transcatheterization procedures. The Mitraclip device is then advanced
over this guidewire into the left atrium for appropriate positioning.
Orienting and positioning the device can be challenging, requiring
a team-based approach with ultrasound guidance for proper
alignment. Once the clip is in place, the surgeon will create tension
by clamping the clip around the leaflets. This will create a u-shape,
the desired 'closed-door' effect, allowing the blood to pump
normally between the chambers (Figure 1.2, 1.3).
Figure 1.2: Mitraclip has punctured
the left atrium but is not yet placed.
The V-position seen in the left-upper
part of the image indicates that the
clip is not yet in its desired position
and is being maneuvered around
the leaflets. At this point, the clip
is still attached to the guidewire.
(echocardiogram of a patient from
Reading Hospital study)
Figure 1.3 The guidewire has been
removed, and the surgeon's team
has placed and closed the clip in the
desired u-shaped position, securing the
leaflets in place. The upper left corner
of the echo is a view of the mitraclip
sitting between the left atrium and left
ventricle, the clip having been securely
positioned within the valve opening.
(echocardiogram of a patient from Reading Hospital study)

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BCMS Medical Record Fall 2020

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