If a patient is diagnosed with heart problems, an examination with a cardiac catheter often follows. This usually involves imaging the heart and coronary arteries using contrast media and X-ray procedures, followed directly by therapy if necessary. This procedure is used about 700,000 times a year in Germany.
What is a cardiac catheterization examination?
During a cardiac catheterization examination, a thin plastic tube (catheter) is inserted into the vascular system through a vein (right heart catheter, “small heart catheter”) or an artery (left heart catheter, “large heart catheter”). With the aid of a contrast medium injected into the catheter, the heart and vessels are made visible in an X-ray image. In most cases, left heart catheterization in particular is not only performed for diagnostic purposes, but is coupled with a therapeutic procedure in the same session.
What are the risks?
The cardiac catheterization examination definitely carries risks – in addition to bleeding or bruising at the puncture site, especially cardiac arrhythmias, heart attacks, strokes or vascular injuries. The contrast medium used in coronary angiography can cause allergic reactions and (temporary) impairment of kidney function. Elderly people or those with chronic diseases such as kidney or heart failure are particularly at risk. Therefore, the risks must always be balanced against the hoped-for benefits.
The left heart catheter
The more commonly performed catheter examination of the left heart is used to diagnose abnormal changes in the coronary arteries, heart valves, heart muscle, or heart defects of the valves at the left atrium or left ventricle. Knowledge of the exact location of constrictions in the coronary arteries is necessary in order to perform, for example, vasodilatation with the aid of a balloon (balloon dilatation) or bypass surgery. For the examination, after local anesthesia, the catheter is advanced to the left ventricle via a puncture site in the groin (or, more rarely, via an exposed artery in the crook of the arm) against the direction of flow. An X-ray contrast medium is then injected into the left ventricle, the aorta and the left and right heart arteries. On the monitor, the doctor can then determine exactly where the vessels are narrowed or blocked. This part of the left heart catheterization is called coronary angiography and can be supplemented by an ultrasound examination (IVUS = intravascular ultrasound) and a pressure measurement in the vessels (pressure wire).
The right heart catheter
The right heart catheter is used primarily to measure the pressure in the pulmonary arteries and the pumping capacity of the heart. Therefore, it usually does not require contrast or x-ray. The right heart catheter is usually inserted through a puncture site at the crook of the arm, occasionally through the groin. At the tip of the tube is a tiny inflatable balloon that is inserted into the vein with the catheter and then inflated. The balloon is floated with the blood flow into the right atrium and through the right ventricle into the pulmonary artery (hence “float-in catheter”). During the examination, the catheter stops for a short time at each of the different sections of the heart in order to measure blood pressure and blood oxygen saturation at these points. Elevated pressures in the pulmonary circulation may be signs of impaired blood flow to the heart muscle.
Stress testing as an additional examination
Often, right heart catheterization is combined with exercise stress testing. This involves the patient pedaling a bicycle while lying down. The values measured during this physical stress are then compared with the corresponding resting values, providing information about cardiac function as a whole. This difference in values is particularly important in assessing the effectiveness of the heart valves. Elevated pressures in the pulmonary circulation during exercise can also be a measure of the size and effectiveness of cardiac septal defects. However, if pathological changes in the right side of the heart are suspected, a contrast-controlled X-ray examination can of course be performed via the right heart catheterization.
Cardiac catheter as a therapeutic tool
During a cardiac catheterization examination, direct therapeutic measures are usually performed, such as dilatation of the coronary arteries (PTCA) with the aid of an expansion balloon or additional stabilization of the vessel wall by means of a support grid (stents). Heart muscle biopsies are also possible. In this case, there is a forceps instrument on the catheter that can be used to remove a tissue sample.
