Impella; The World’s Smallest Heart Pump

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Impella
The World’s Smallest Heart Pump; Impella

Impella is the world’s smallest heart pump. It is a mechanical device that is temporarily used for ventricular support in patients with depressed heart function.

Impella

These are small in size and introduced into the body through the skin of the groin.

These small heart pumps are inserted through a peripheral artery in the groin. This artery is the femoral artery. After gaining access in the femoral artery, the technology is advanced into a bigger artery of the heart and then finally into the left side of the heart.

 Uses of Impella

Impella provides mechanical circulatory support in following conditions:

  • In a hemodynamically unstable patient i.e. patient having low blood pressure unable to perfuse organs of the body insufficiently.
  • Patients suffering from cardiac failure.
  • Patients suffering from cardiogenic shock.
  • Patients with a depressed heart function after a heart attack or open-heart surgery.

The smallest heart pump

How does it work?

The heart normally distributes about 5L of blood to the whole body per minute with effective pumping. This is called cardiac output. When this function is depressed, there is a decreased cardiac output and the body does not get enough blood and oxygen. For normal functioning of each organ of the body, a proper blood supply is required. This blood flow provides nutrients and oxygen to the organs. Hence, if the heart doesn’t pump enough blood to these organs especially in the case of the brain, it can be life-threatening.

Impella

The depressed functioning of the heart can be due to:

  • Decreased contractility of the heart muscle as in heart failure: the heart becomes an ineffective pump.
  • Heart attack: decreased blood flow to heart muscles can cause inefficient working of these muscles and can sometimes completely shut the heart function and leads to a condition called cardiogenic shock.

When the heart doesn’t work properly it gets pooled with blood which puts stress on the heart muscle. Impella decreases this load and stress on the heart and pumps blood from ventricular cavity into the big vessels to get distributed into the body. Therefore, it has a number of advantages.

Impella in Heart

Advantages

  • Increases cardiac output
  • Decreases ventricular load
  • Decreases ventricular wall stress
  • Decreases oxygen demand of the heart
  • Decreases lung pressures
  • Increases the blood supply to organs

It improves these functions just 30 minutes after implantation.

The Impella aspirates blood from the left ventricle and pumps it into the ascending aorta. The amount of flow depends on the rotation speed and on the pressure gradient between the aorta and the LV.

Routes for implantation

Mostly the femoral approach is utilized but axillary or subclavian routes are not uncommon. The femoral artery is easily accessible and provides a good area to the surgeon as the artery is of the larger lumen.

 Structure of Impella

There are different types of Impellas depending on how much cardiac output they provide. Thus, they range from 1-5 L/min.

For example, Impella 2.5 provides a cardiac output at a rate of 2.5 L/min.

The Impella 2.5 is a 12F (French: unit for the lumen of the Impella) pump suspended on a 9F catheter and is introduced via the skin through the femoral artery using a Seldinger technique.

On September 10, 2012, Abiomed, Inc. received acceptance from the US Food and Drug Administration for a new and advanced flow version of its percutaneous, catheter-based Impella heart pump. The new Impella CP (Cardiac Power) is a 14F pump suspended on a 9F catheter and can provide peak blood flows of approximately 4 L/min using the same effective platform as the Impella 2.5.

The Impella CP provides for partial circulatory support using an extracorporeal bypass control unit for the duration of up to 6 hours. It is also destined to provide partial circulatory support (for the duration of up to 6 hours) during procedures which do not require cardiopulmonary bypass. The safety and effectiveness of the Impella CP have not been established for use in providing partial or full support of the blood circulation for the duration of more than 6 hours.

Structure

Blood Inlet Area:

Blood is entered into the device through this end. It is placed inside of the ventricular cavity few centimeters away from the aorta. Blood is directed away from the cavity towards the large vessel.

Blood Outlet Area

Blood leaves the pump through this end into the aorta and thus decreases the ventricular pre-load and wall stress increasing the cardiac output.

Pump Motor

12 Fr motor helps in aspiring blood from the lumen of the left ventricle and pumping it towards the aorta.

Some of the potential complications

Following complications can arise:

The occurrence of hemolysis

This mechanical device can break down red blood cells. This is called hemolysis. When blood cells pass through this device, they can burst out of shear stress.

Thrombocytopenia

It means the low number of platelets. Platelets can be similarly destroyed as red blood cells when they face mechanical stress.

Bleeding

The risk of bleeding can be increased because of the decreased number of platelets or the use of medications that are taken for decreasing the clotting tendency of blood.

Risk of infection

The insertion of Impella through the skin introduces bacteria in the blood and thus can lead to infections.

vascular complications related to the device insertion

The complications could be major bleeding from the insertion site and limb ischemia (decreased blood supply to the limb).

There is also the risk of injury to the aortic valve related to the prolonged use of the device. This can be in the form of aortic insufficiency although rarely reported or mild to moderate aortic regurgitation. These findings have been seen on echocardiography in case of prolonged use of Impella.

Also read: Remote Patient monitoring RPM

Conclusion

We are looking forward to the use of Impella in cardiac arrest patients. Cardiac arrest is a term used when the heart stops beating. There are several causes of cardiac arrest. There are not sufficient trials to use impeller in these patients yet but if their use is approved, it can go on a long run for the survival of these patients.

Earlier Impella implantation after cardiac arrest may provide cardiac support and tissue perfusion until recovery or high-risk PCI.  However, Impella is not feasible to use in CPR situations routinely since some cardiac arrest is not cardiac especially ischemia related. Impella is more suitable to use in ischemia-related cardiac arrest, especially when cardiac intervention is needed.

Reference:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578627/

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