Page 62 - Critical Care Notes

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CV

Ventricular Assist Devices (VADs)
■ VADs are used in the treatment of acute or chronic heart failure refractory
to standard treatment and a failing heart. Supports the left ventricle (LVAD),
the right ventricle (RVAD), or both ventricles (BIVAD). They improve end-
organ function, quality of life, and extend survival. May be used short or
long term and implanted internally or located externally.
■ The devices are also categorized as pulsatile or nonpulsatile (newer pumps,
continuous flow).
■ Continuous flow pump: Nonpulsatile; continuously fills and returns
blood to a major blood vessel at a constant preset rate.
■ Pulsatile pump: Fills during systole and pumps blood into aorta during
diastole or pulmonary artery or may pump regardless of the patient’s
(native) cardiac cycle.
■ All devices use the same concept. Blood is removed from the failing ventri-
cle and is diverted into a pump that delivers blood to the aorta (in the case
of the LVAD) or the pulmonary artery (in the case of the RVAD).
■ LVADs can often be placed temporarily and serve as a bridge to recovery in
patients with acute, severe myocarditis or post cardiotomy. In patients with
end-stage heart failure, VADs are a bridge to heart transplantation that
allows some patients to undergo rehabilitation and possibly go home
before transplantation.
■ Long-term use may be considered when no definitive procedure is planned,
and life-long use may be considered if patient is not a candidate or does
not want cardiac transplantation.
■ Procedure:
■ Done under general anesthesia; a sternotomy is performed. A “pericar-
dial cradle” is created with sutures to lift the heart up for better visualiza-
tion of the heart structures.
■ A pump pocket is then created to make a space for the device to sit in
(extraperitoneal, an area below the rectus abdominis and internal oblique
muscles and above the posterior rectus sheath, or intraperitoneal).
■ After the pocket is prepared and the patient is cannulated, cardiopul-
monary bypass is initiated. An inflow cannula is placed in the LV apex
and secured with sutures.
■ The pump is placed in the abdominal pocket, the length of the outflow
graft is measured (should lie under the right sternal border), and the
driveline (a tunneling device) is performed. This is done by placement
through a skin incision to the right of the umbilicus and tunneled to the
device pocket.
■ The outflow cannula is placed, then de-aired; the patient is weaned from
cardiopulmonary bypass, and the device is activated.
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