Impella
1. What is Impella?
Impella is one of the circulatory support devices designed to assist the left ventricle’s function of pumping blood throughout the body in patients whose heart function has severely deteriorated due to conditions such as acute myocardial infarction. It works by inserting a catheter with an ultra-small pump into the left ventricle, which draws blood from the left ventricle and pumps it into the ascending aorta, thereby supporting the heart’s pumping function. When heart function severely declines due to conditions like myocardial infarction, the amount of blood circulating throughout the body decreases, leading to insufficient blood pressure maintenance (cardiogenic shock). In cardiogenic shock, blood flow to organs such as the brain and kidneys decreases, causing various organ dysfunctions. Impella is used to help overcome this condition. It has been available in Europe since 2005, in the United States since 2008, and became available in Japan in September 2017.
There are several types of devices called circulatory support devices that help the pumping function of a weakened heart. The main circulatory support devices include: ①IABP (Intra-Aortic Balloon Pump), which expands and contracts a balloon in the aorta in sync with the heart’s contraction and relaxation, ②ECMO (Extracorporeal Membrane Oxygenation: also called PCPS), which is essentially an external artificial heart-lung machine, ③VAD (Ventricular Assist Device), which is a type of artificial heart directly implanted into the heart, and now ④Impella, which has been developed as a percutaneous left ventricular assist device.
Impella is a circulatory support device that can provide circulatory support through a relatively minimally invasive (small wound) procedure. In addition to maintaining blood flow to organs, the built-in artificial pump takes over the work of the heart, reducing the heart’s burden of pumping blood throughout the body, which is expected to contribute to the recovery of heart function (this is called unloading). This is a unique advantage of Impella that differs from conventional circulatory support devices. Furthermore, for more severe patients, it may be used in combination with the aforementioned ECMO (external artificial heart-lung machine).
The characteristics of each mechanical circulatory support are summarized in the table.
2. Target Patients
The indication is “acute heart failure resistant to drug therapy, such as cardiogenic shock”. It is particularly expected to be effective for patients whose cardiac output has drastically decreased due to acute myocardial infarction or severe myocarditis, also known as fulminant myocarditis. As mentioned earlier, in the most severe cases where not only the heart but also respiratory failure is present, Impella may be used in combination with ECMO (this combination is called ECPELLA) to expect the effect of reducing left ventricular load.
3. Types and Characteristics of Impella
There have been several types of Impella based on their size and the amount of blood flow they can support, but currently in Japan, the available types are:Impella CP®, Impella 5.5® (two types).
Impella CP® is typically inserted through the femoral artery in the groin area, while Impella 5.5® is inserted through the subclavian artery (under the collarbone) via a surgical procedure using an artificial blood vessel. They differ in terms of ease of placement, maximum support flow, expected duration of use, and the need for lower limb immobilization (possibility of rehabilitation). Our hospital’s heart team discusses and selects the most appropriate device for each patient.
