BME 312 BIOMEDICAL INSTRUMENTATION II
LECTURER: ALİ IŞIN
LECTURE NOTE 2 BLOOD PUMPS
FACULTY OF ENGINEERING
DEPARTMENT OF BIOMEDICAL ENGINEERING
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).
Intra Aortic-Balloon Pump
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
Intra Aortic-Balloon Pump..
• Pressurized CO
2is applied to the balloon for inflating.
• CO
2is 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.
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 CO
2supplied to the balloon.
• Appropriate sensors are included in the system to
ensure that alarms are sounded if any leaks occur.
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.
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.
Example of one VAD device:
HeartMate ® Implantable
Apex
Titanium Pump Ascending Aorta
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.
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
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
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
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.
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.
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.
