Medical Background

Myocardial Infarction

A myocardial infarction is another term for a heart attack. A heart attack occurs when sections of the heart muscle do not receive enough oxygen, primarily due to occluded coronary arteries. Since the heart muscle cells, like all muscle cells in the body, need oxygen to live, the areas of the heart muscle (cells) that are supplied by the blocked arteries die. A section of dead heart muscle is called an infarcted area.

Heart Attack ("Myocardial Infarction")

Stem Cells

A stem cell is a special kind of cell that has a unique capacity to renew itself and to give rise to specialized cell types. Although most cells of the body, such as nerve cells or muscle cells, are committed to conduct a specific function, a stem cell is uncommitted and remains uncommitted, until it receives a signal to develop into a specialized cell. Their proliferative capacity combined with the ability to become specialized makes stem cells unique. Researches have for years looked for ways to use stem cells to replace cells and tissues that are damaged or diseased.

Cardiac Stem Cell Therapy

Within the scope of clinical studies performed at the General Hospital of Linz and the Red Cross Blood Center Linz, the treatment of myocardial infarctions with (adult autologous) stem cells is investigated. Whereas molecular biologists of the Blood Center Linz specialized in harvesting stem cells, cardiologists of the General Hospital primary focused on the transplantation.

After a patient has obtained standard cardiac therapy (e.g. balloon dilatation of occluded coronary arteries, stent implantation), harvesting and transplantation of stem cells is carried out in the following way:

• During the days after the infarct, the patient obtains medication causing stem cells to be flushed out into the bloodstream.

• Blood tests are made and examined every day. If they indicate that the peak of stem cells in the blood is reached (after about 4-6 days), stem cells will be harvested.

• Stem cells are "filtered out" from the patient's blood by special dialysis equipment and then prepared by molecular biologists of the Blood Center. After approximately 5 hours of filtering and preparation, stem cells can be transplanted by cardiologists.

• Via a special balloon catheter, stem cells are injected into the coronary artery supplying the infarcted zone. There, they ideally develop to new heart muscle cells and regenerate heart muscle functionality by reducing the area of the infarcted zone.

Stem Cell Transplantation

Coronary Angiography

The "golden standard" in cardiology for diagnosing the impact of a heart attack and making heart activity visible is coronary angiography. During this procedure, a catheter is inserted into the patient's body (iliac region) and moved to the anatomic cardiac region of interest, e.g. the left heart chamber, the right heart chamber or the coronary arteries. Via the catheter, contrast agent is injected and at the same time, a sequence of x-ray images are recorded (3-6 seconds). Since the contrast agent is radiopaque, x-rays decrease when passing through the body/contast agent and therefore the anatomy of interest is made visible on x-ray images. An example image sequence can be found here.

As shown in the figure below, the x-ray equipment primarly consists of a patient table and two C-shaped arcs, called "C-arms". Each C-arm consists of an x-ray source (emitting x-rays) on the one end and an image intensifier (detecting and recording x-rays) on the other end. Both C-arms can be rotated around two mechanical axes of the equipment in order to select the desired view. Usually, "biplanar mode" is used during recording, meaning that both C-arms are in operation and therefore images synchronously recorded from two different views are available for analyses.

In contrast to other medical imaging techniques like MR or CT, the images produced by coronary angiography x-ray equipment do not represent slices of the monitored object but projections of the object (analogy: 2D shadow of a lighted 3D object projected on a wall).

Biplanar X-Ray Angiography (Siemens HICOR)