If a patient is diagnosed with heart problems, it is often followed by cardiac catheterization. The heart and the coronary arteries are usually visualized by means of contrast media and X-ray procedures, if necessary followed directly by therapy. This procedure is used in Germany around 700, 000 times a year.
What is a cardiac catheter examination?
In a cardiac catheter examination, a thin plastic tube (catheter) is inserted into the vasculature via a vein (right heart catheter, "small cardiac catheter") or an artery (left heart catheter, "large cardiac catheter"). With the aid of a contrast medium injected into the catheter, the heart and vessels are visualized in the X-ray image. In most cases, the left heart catheter examination is not only performed for diagnostic purposes, but coupled with a therapeutic procedure during the same session.
The cardiac catheter examination certainly involves risks - in addition to bleeding or bruising at the site of puncture, especially cardiac arrhythmias, heart attacks, strokes or vascular injuries. The contrast agent used in coronary angiography may lead to allergic reactions and (transient) impairment of renal function. Particularly at risk are older people or those with chronic diseases such as kidney or heart failure. Therefore, the risks must always be balanced with the hoped-for benefits.
The left heart catheter
The more frequent left ventricular catheterization will diagnose abnormal changes in the coronary arteries, heart valves, myocardium or heart defects of the left atrial or left ventricular valves. Knowledge of the exact location of constrictions in the coronary arteries is necessary, for example, to perform a vessel dilation with the aid of a balloon (balloon dilatation) or a bypass operation.
For examination, after local anesthesia, the catheter is advanced against the flow direction to the left ventricle via a puncture site in the groin (or more rarely via an exposed artery in the elbow). Then an X-ray contrast agent is injected into the left ventricle, the main artery and the left and right coronary arteries. On the monitor, the doctor can then determine exactly where the vessels are narrowed or closed.
This part of the left heart catheter examination is called coronary angiography and can be supplemented by an ultrasound examination (IVUS = intravascular ultrasound) and a pressure measurement in the blood vessels (pressure wire).
The right heart catheter
The right-heart catheter measures the pressure in the pulmonary arteries and the pumping power of the heart. Therefore, one usually comes without contrast medium and X-ray. The right-heart catheter is usually inserted through a puncture site on the crook of the arm, occasionally over the groin. At the top of the tube is a tiny inflatable balloon, which is inserted into the vein with the catheter and then inflated. The balloon is flushed with the bloodstream into the right atrium and through the right ventricle into the pulmonary artery (hence "infiltration catheter").
During the examination, the catheter stops for a short time at the various sections of the heart, in order to measure the blood pressure and the oxygen saturation of the blood at these points. Increased pressure in the pulmonary circulation can be a sign of a circulatory disorder of the heart muscle.
Stress test as additional examination
Often, the right heart catheter is associated with a stress test. In doing so, the patient enters a bicycle pedal while lying down. The values measured with this physical load are then compared with the corresponding resting values and thus provide information about the heart function as a whole. This value difference is especially important in assessing the effectiveness of heart valves.
Increased pressures in the pulmonary circulation during exercise may also be a measure of the size and effectiveness of heart septum defects. If suspected pathological changes in the right half of the heart but also on the right heart catheter and a contrast agent-controlled X-ray examination can be performed.
Cardiac catheter as a therapy instrument
As part of a cardiac catheterization usually direct therapeutic measures such as the expansion of the coronary arteries (PTCA) using an expansion balloon or additionally the stabilization of the vessel wall by means of a support grid (stent) is performed. Cardiac muscle biopsies are also possible. In this case, there is a pliers instrument on the catheter with which a tissue sample can be taken.