Coronary angiography A cardiac catheter examination is a diagnostic or therapeutic measure to detect and correct cardiovascular changes with the help of a catheter inserted into the vascular system. A cardiac catheter is a very thin, internally hollow instrument several meters long, with a guide wire in its central cavity. This guidewire serves to guide the direction and path of the catheter (heart catheter), which is actually not rigid.
The guidewire can be inserted and removed variably. The tip of the catheter is slightly bent. If the guide wire is not inserted, the bend at the tip remains. When the guide wire is inserted, the bend at the tip is cancelled. When the guide wire is withdrawn, the catheter cavity offers the possibility to either inject liquid in the form of contrast medium or to advance further instruments up to the catheter tip (heart catheter).
Cardiac catheter examination – outpatient or inpatient?
Cardiac catheterization is a routine procedure for the reliable visualization of cardiac vessels. Thanks to modern technology, the procedure is relatively uncomplicated. But it is not free of complications.
However, this is more likely to occur in emergencies, serious pre-existing conditions and an overall very reduced general condition of the patient. Contrast agent incompatibilities may occasionally occur. For this reason, cardiac catheterization is generally performed on an outpatient basis on an awake patient under local anesthesia.
If no complications occur, the patient can leave the clinic the same day. This applies to examinations without intervention. In case of post-operative bleeding at the injection site, the patient usually stays overnight and can leave the clinic the next day without further complications.
More serious complications may require longer hospital stays. This happens rather rarely and depends on the nature of the problem and the patient’s general condition. Normally, patients should take it easy for 3 to 4 days after the examination and should be on bed rest on the day of the examination.
Overall, cardiac catheterizations are performed on an outpatient basis if the course of the disease is free of complications. Before a cardiac catheterization (cardiac catheterization) some preliminary examinations have to be performed. These consist of an ECG at rest and a stress ECG, blood count with coagulation values, kidney and thyroid values to rule out the possibility of a contraindication for a contrast medium examination, and an X-ray of the lungs.
The aim of cardiac catheterization is to visualize the vascular system of the heart in order to see and correct constrictions or occlusions. A cardiac catheter examination takes place in the so-called cardiac catheter laboratory, an operating room similar to an operating room, which is kept particularly sterile and is equipped with a couch and an X-ray machine. This X-ray unit is attached in the form of an arch above the examination couch and can be rotated around the patient.
In order to make the heart vessels visible, the catheter has to be advanced into the heart. To do this, either a peripheral vein (right heart catheter) or an artery (left heart catheter) is punctured. The puncture of an artery is performed more often.
In most cases, the inguinal artery is used as the access point. After locating the appropriate puncture site, a so-called sheath is inserted. This serves to keep the access open and at the same time to avoid bleeding caused by the high arterial pressure.
The catheter (heart catheter) is then slowly pushed forward through the vascular system through this airlock. To clear the way, the guide wire is first pushed forward. It consists of a metal connection.
During the advancement, the examiner can determine the current position of the wire precisely by means of regular X-ray snapshots. The goal of the cardiac catheter is the point of origin of the coronary arteries. The coronary arteries leave the aorta just above the aortic valve.
As soon as the safe position of the wire is ensured by an X-ray image, the blood vessels supplying the heart with oxygen-rich blood (coronary arteries) are displayed. The catheter is pushed over the wire and a contrast medium is injected through the actually hollow catheter into the coronary arteries, which are quickly distributed throughout the heart muscle. The X-ray image now shows in real time how the vascular system fills with contrast medium and how continuous the blood vessel system is.Constrictions and occlusions become apparent in the form of a contrast medium recess.
During the examination it is possible to document the examination and the results in the form of a video or photos. If constrictions of the coronary vessels are found, it is possible to expand the vessel via a balloon inserted through the heart catheter and thus make it passable again. This method is also known as PTCA (percutaneous transluminal coronary angioplasty).
The balloon is limply pushed over the heart catheter to the narrowed area and then unfolded. The pressure on the constricted vessel causes it to expand. It is also possible to insert a stent into the constricted or occluded vessel.
A stent is a small tube of a special material similar to a mesh wire. A stent can also be inserted via the catheter probe (heart catheter) and pushed into the constricted area. Similar to a balloon, it is pushed over the heart catheter in a folded state and unfolded after reaching the correct position.
This keeps the vessel open. Several stents can be inserted in one catheter session and several PTCA can be performed. In the case of completely occluded vessels that have led to a heart attack, a stent is almost always inserted, as it can more successfully hold the vessel open.
For moderately to moderately narrowed vessels, PTCA is often sufficient. In some cases, a stent may also close up again after a while. In this case, the procedure must be repeated.
Newer materials are now coated with a radioactive material. This is intended to prevent deposits from settling on the inner wall of the stent and sealing it over time. Which material is used depends on the severity of the vascular disease, the patient’s condition and the examiner.
After dilation of the vessel and after comprehensive radiological imaging of the coronary artery system, the cardiac catheter is returned to the outside. A few minutes later the sheath is pulled out and a pressure bandage is applied. This must not be removed until 24 hours after the examination.
In the meantime, however, the time required is being shortened accordingly. The patient should move and lie down as little as possible during this time. Before the dressing is removed, the puncture site must be examined by a doctor.
The doctor listens to the areas above and next to the vessel with his stethoscope and checks whether there is any flow noise or a hematoma. The pressure dressing can only be removed if the puncture site is without findings. The reason for these precautionary measures is that the arterial vascular system is under enormous pressure.
Post-bleeding occurs relatively frequently. After stent implantation, the patient should take an ASA-clopidogrel combination to ensure that the blood remains thin and does not begin to clot on the stent. A cardiac catheter examination is always performed if there is a suspicion of acute coronary syndrome, heart attack or angina pectoris attack.
Patients who report pain or pressure on the chest during exercise or at rest are potential candidates for cardiac catheterization. After a confirmed myocardial infarction (ECG changes, laboratory changes, and patient’s clinic), a cardiac catheterization is usually performed to confirm and treat a heart attack. Depending on the region and accessibility of the nearest cardiac catheterization laboratory, an examination is performed.
If the next laboratory cannot be reached quickly enough, the blood must first be diluted by means of drug lysis. However, there are numerous cardiac catheter laboratories in large conurbations in Germany, so this type of examination is the method of choice for heart attacks. Prolonged discomfort on the chest during movement (stable angina pectoris) or at rest (unstable angina pectoris) can also be diagnosed and treated with a cardiac catheter examination (heart catheterization). A cardiac catheterization (cardiac catheterization) should not be performed if the patient has a highly elevated potassium level or digitalis level in the blood, if there is an infection or sepsis, if there is uncontrolled hypertension or decreased blood pressure, if there is a contrast medium allergy, if the patient suffers from renal insufficiency, if the patient has problems with blood clotting, or if a cardiac catheterization is of insufficient diagnostic or therapeutic value.Furthermore, no cardiac catheterization should be performed if there is a so-called tachycardia (very fast pulse rate), a pronounced heart failure, an inflammation of the heart valves or the heart muscle or pericardium, or if the patient is in pulmonary edema.
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