Transcript Blood Pumps

FACULTY OF ENGINEERING
DEPARTMENT OF BIOMEDICAL ENGINEERING
BME 312 BIOMEDICAL
INSTRUMENTATION II
LECTURER: ALİ IŞIN
LECTURE NOTE 2
BLOOD PUMPS
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Blood Pumps
• Mechanical devices used to assist the heart in
circulating the blood.
• Aids the failing heart after a surgery
• Reduces the load driven by heart
• Some advanced pumps can completely
replace the heart (Artificial Heart).
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Intra Aortic-Balloon Pump
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Intra Aortic-Balloon Pump.
• Used to increase myocardial oxygen delivery by
increasing coronary blood flow.
• Consists of a long cylindrical polyethelene balloon
that can be introduced into the aorta through a
femolar (thigh related) artery and connected to an
external drive apparatus.
• It actively deflates in systole, increasing forward
blood flow by reducing the load. It actively inflates
in diastole, increasing blood flow to the coronary
arteries.
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Intra Aortic-Balloon Pump..
• Pressurized CO2 is applied to the balloon for
inflating.
• CO2 is used because it is more soluble in blood
than air. Thus, there is less risk of fatal gas
embolism
(obstruction
of
the
circulatory system caused by an air bubble) if
the balloon or its supply tubing leaks or
rupture.
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Intra Aortic-Balloon Pump…
• The device rely on electronic controls to detect
ventricular contraction either from a pressure
sensor at the arch of the aorta or from the ECG.
• The signal then go through appropriate delay
circuits to control the suction and pressurized CO2
supplied to the balloon.
• Appropriate sensors are included in the system to
ensure that alarms are sounded if any leaks occur.
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Ventricular Assist Device (VAD)
• A ventricular assist device (VAD) is a
mechanical pump used for temporary blood
circulation support. It decreases the workload
of the heart while maintaining adequate flow
and blood pressure.
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Purpose
• A VAD is a temporary life-sustaining device. VADs can
replace the left ventricle (LVAD), the right ventricle
(RVAD), or both ventricles (BIVAD). They are used
when the heart muscle is damaged and needs to rest
in order to heal or when blood flow from the heart is
inadequate. VADs can also be used as a bridge in
patients awaiting heart transplantation or in
patients who have rejected a transplanted heart.
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Example of one VAD
device:
HeartMate ® Implantable
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Ascending Aorta
Apex
Titanium Pump
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The VAD consists of:
• A pump unit, implanted in the abdomen (location of placement is based
on the patient's past medical history, anatomy and surgeon preference)
• An inflow tube (or conduit), attached to the bottom of the left ventricle
(apex)
• An outflow tube, attached to the aorta (the large artery that carries blood
away from your heart)
• Internal valves that allow for one-way blood flow through the system
• Power leads, that pass from the internal device through the skin, and
outside your body. The outside of the tube is covered with a special
material so that skin cells grow into the material and aids healing.
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The VAD consists of:
• External controller and power base unit or battery pack that attaches to
the power leads/cables. The controller is programmed to maintain a
specific pump spread. It displays the status of the system and any alarm
messages, and also sounds alarms if needed. The batteries are
rechargeable and changed daily.
• The controller and batteries can be worn in a belted waist pack or a
holster under the arm. Or, it may be connected to a power base unit and
plugged into a wall outlet.
• The type of pump and other components depends on the type of VAD
used
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Mobility and freedom
• The VAD allows patients to be mobile, and return
home. A detailed education program is provided to
the patient and family, or patient support system, to
ensure safety and proper use of each of the
components. The patient must demonstrate
independence with self care, and management of
the device and potential emergency situations before
leaving the hospital
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Patients who might be candidates for
a VAD
• Examples:
• have suffered a massive heart attack
• cannot be weaned from heart-lung bypass after treatment
with intravenous fluids, medications, and insertion of a
balloon pump in the aorta
• have an infection in the heart wall that does not respond to
conventional treatment
• are awaiting a heart transplant and are unresponsive to drug
therapy and intravenous fluids
• are undergoing high-risk procedures to clear the blockages in
a coronary artery
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Types of VADs
• There are four types of VADs, each appropriate for a different
condition. Surgery to install a VAD is performed under general
anesthesia in a hospital operating room. An incision is made in
the chest, then catheters are inserted into the heart and the
correct artery. The surgeon sutures the catheters in place,
then attaches tubing to connect the catheters to the pump.
The pump stays outside the body. Once it is turned on, blood
flows out of the diseased ventricle and into the pump, then is
returned to the correct blood vessel leaving the heart.
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After insertion
• The patient is monitored in intensive care, with
follow-up blood, urine, and neurological studies.
Blood thinning medications are given to prevent
blood clotting.
• Except for those patients awaiting a heart transplant,
patients are slowly and gradually weaned from the
VAD. Even when patients no longer need the VAD,
they will require supportive drug therapy and/or a
balloon pump inserted in the aorta.
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Risks
• Bleeding from surgery is common and occurs in as
many as 30-50% of patients. Other complications
include the development of blood clots, partial
paralysis of the diaphragm, respiratory failure,
kidney failure, failure of the VAD, damage to the
coronary blood vessels, stroke, and infection.
• Sometimes when the left ventricle is supported, the
right ventricle begins to need assistance. If VADs are
inserted in both ventricles, the heart may become so
dependent on their support that they cannot be
removed.
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Roller Pump
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Roller Pump – Eccentric Shaft
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Multiple Finger Pumps
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Pumps
• Roller pumps and Multiple-finger pumps
are employed because the pump itself
does not come in contact with the blood.
• Disposable, flexible tubing are used to
contain blood that is pinched between
the propagating rollers or fingers.
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Reciprocating Pump
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Pulsatile Pumps
• Pulsatile pumps - consisting of a chamber
subjected to the reciprocating motion of
a piston, membrane, or bladder - are also
used with appropriate check valve to
direct the flow.
• Such pumps more closely follow the
normal action of the heart and produce a
pulsatile blood pressure.
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Pump Oxygenators
• Can carry out both blood pumping and blood
oxygenation.
• Consists of
• Pumps for maintaining arterial blood pressure
• Oxygenators connected in series with the pump
that increase blood O2 content and remove CO2.
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Pump Oxigenators
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Oxygenators
• Used for patients who have severe lung diseases.
• Two types of Oxygenators:
• Film type
• A large-surface-area film of blood is drawn into
contact with a nearly 100% O2 atmosphere by
rotating disks.
• Membrane Oxygenator
• Blood flows through fine tubes of a membrane
permeable to gas
• Has a large exchange surface area to allow the gas
transfer to takeBME
place.
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Total Artificial Heart
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Total Artificial Heart
• Blood pumps have been miniaturized and
constructed of such materials that they can
replace the natural hearts of patients
• Implanted in the thoracic cavity and operate
via pneumatic and electric connections to an
external drive apparatus.
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