Diagnostic cardiac catheterization (CCU) is a minimally invasive diagnostic procedure in cardiology and radiology that can be used primarily to assess myocardial anatomy (heart muscle). Basically, cardiac catheterization can be divided into left heart catheterization and right heart catheterization, in which the respective ventricle is examined. In contrast to left heart catheterization, however, right heart catheterization is performed relatively rarely. Both venous and arterial vessels in the groin, (femoral artery) in the crook of the arm or in the area of the wrist (radial artery) are available for performing a cardiac catheter examination, through which the catheter can be inserted. In the heart, the focus of assessment is on the examination of coronary (coronary vessels), valvular (heart valves), myocardial (heart muscle), endocardial (inner layer of the heart) and pericardial (pericardial sac) dysfunctions. The main advantage of cardiac catheterization compared to CT angiography of the heart (a method of visualizing blood vessels in the body using multislice computed tomography) is the possibility of simultaneous intervention, i.e. simultaneous treatment of stenotic coronary vessels (narrowed heart vessels) by balloon dilatation or stenting. Subsequent comments concern left heart catheterization with coronary angiography.
Indications (areas of application)
- Stable angina pectoris (“chest tightness”; sudden pain in the cardiac region caused by a circulatory disorder of the myocardium; the pain character of the attacks is always the same and the symptoms subside with appropriate countermeasures (physical rest, drug therapy)) – The degree of evidence for performing a diagnostic cardiac catheterization depends on the severity of the angina pectoris.
- A high level of evidence exists when high-grade stable angina CCS III and IV (Canadian Cardiovascular Society-designed classification for severity of stable angina) is present despite medical therapy. The highest level of evidence is also present in high-risk patients after successful resuscitation.
- A lower level of evidence is present when improvement occurs with drug therapy despite a CCS III or IV, or no improvement is evident with drug therapy in angina pectoris CCS I and II. Low CCS and a low risk profile have the lowest level of evidence.
- Unstable angina (unstable angina (AP) is defined as any sudden change in clinical presentation: first occurrence of AP; AP at rest; increase in attack duration, attack frequency, and pain intensity with inadequate drug response) – Cardiac catheterization is almost always performed for this form of angina, unless revascularization is foregone because prolongation of life is not realistic.
- Acute infarction (myocardial infarction/heart attack) – If suspected, catheterization is primarily performed with the aim of performing a PTCA (percutaneous transluminal coronary angioplasty; procedure to dilate or reopen narrowed or occluded arteries, e.g., by means of balloon dilatation (dilatation of a stenosed vessel section with the aid of a balloon catheter), laser, etc.).
- After revascularization (revascularization; reopening of vessels) – The highest evidence for performing a diagnostic cardiac catheterization is when the patient shows symptoms within nine months after PTCA or the patient belongs to the high-risk population even in the absence of symptoms.
- Valvular heart disease – In cases of vitiation (valvular heart disease) such as aortic stenosis or mitral regurgitation or stenosis, the procedure can be used to assess left ventricular function and other conditions.
- Heart failure (cardiac insufficiency) – Cardiac catheterization is performed during the course of almost any heart failure.
Contraindications
Absolute contraindications
According to current guidelines, there are no absolute contraindications to diagnostic cardiac catheterization. Relative contraindications
- Elevated serum potassium level-Cardiac catheterization should not be performed if a severely elevated potassium level is measured in the patient’s serum. However, laboratory error or sampling error must be ruled out.
- Elevated Digitalis Levels – Digitalis use may be indicated for tachyarrhythmias (combination of arrhythmia (heart rhythm disturbance) and tachycardia (rapid heartbeat)) but must be closely monitored. If the serum level of digitalis is significantly elevated, the test should be omitted if necessary.
- Sepsis (blood poisoning) – In the presence of sepsis, the risk of complications is massively increased, so that a performance of the examination must be precisely weighed.
- Hypertonic crisis – In the case of a massive increase in blood pressure, the risk of the investigation may exceed the benefit, so that the procedure can be used only in individual cases.
- Renal insufficiency (renal impairment) – In renal insufficiency, contrast administration may further reduce renal function. Intravenous administration of fluids before and after the examination can reduce the damage.
- Contrast agent allergy – In case of allergy to the contrast agent, there is a risk of anaphylactic shock, due to which special measures are necessary to perform.
- Coagulation disorders – In the case of congenital bleeding disorders or when taking certain anticoagulant drugs, the examination may not be performed or only with a time delay.
Before the examination
- Medical history – A medical history must be obtained before the examination, specifically addressing risk factors, likelihood of bleeding or thrombosis, and existing allergies. A detailed medication history is also inevitable.
- Cardiological diagnostics – In addition to a current resting ECG (electrocardiogram), an exercise ECG or stress echocardiogram should be performed if surgery is planned. According to the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS), patients with an intermediate probability of chronic CHD should primarily undergo noninvasive diagnostics before undergoing cardiac catheterization. For this purpose, noninvasive functional imaging techniques are used to assess myocardial perfusion (blood flow to the myocardium) (see under Coronary artery disease/Medical device diagnostics) [ESC guideline].
- Laboratory diagnostics – In particular, the parameters hemoglobin (anemia diagnostics; diagnostics to exclude anemia), TSH ((thyroid-stimulating hormone; thyroid level), and creatinine (elevations in serum creatinine often reflect renal impairment) should be determined. Inflammatory parameters (CRP) and coagulation parameters (Quick, PTT) are also usually required.
The procedure
The basic principle of cardiac catheterization is based on the insertion of the catheter with a guidewire through an access (see below) into an artery further via the aorta (main artery) to the heart. Iodine-containing X-ray contrast medium is injected directly into the coronary artery (arteries that surround the heart in a circle and supply the heart muscle with blood) via the cardiac catheter and visualized by X-ray fluoroscopy. The wire is inside the catheter and is primarily used to find the path of the catheter. It is important that the tip of the catheter is curved so that the catheter can glide to the heart with the help of the wire. The wire straightens the tip when the wire remains inside. Contrast material can be applied to the vessel through the catheter. Most often, the transfemoral approach via the groin is preferred for cardiac catheterization. However, access via the radial artery from the wrist is associated with a lower risk of bleeding. A meta-analysis also shows the advantages of transradial access: both the rate of major adverse cardiac events (MACE) (relative risk reduction 16 %) and the overall mortality in the radial access group (1.55 % vs. 2.22 %, OR =0.71, p = 0.001) were significantly lower than in the femoral group.When the catheter is at the target position, imaging of hemodynamics, pressure measurement, and determination of cardiac electrical function can be performed.If intermediate stenosis is present, measurement of fractional flow reserve is performed. Fractional flow reserve (FFR) measurement.
FFR indicates the ratio of the mean blood pressure distal to the stenosis to the mean aortic pressure; considered a measure of how much a stenosis restricts blood flow in the coronary vessel; gold standard for analyzing coronary stenosis; usually measured by invasive coronary angiography. CT-based measurement of FFR is now possible (= CT-FFR); the value can be calculated for any segment of the coronary system. Indication
- Angiographically moderate stenosis in:
- Inconclusive clinic or
- When ischemia is inconclusive or not present.
| FFR value | Interpretation |
| 1 | Normal value |
| > 0,80 | Exclusion of a hemodynamically relevant stenosis. |
| < 0,75 | Hemodynamically relevant lesion |
| Meanwhile, a cut-off value of 0.8 has become accepted | |
Note: The FAME trial confirmed that patients with stable coronary artery disease (CAD) and stenoses with an FFR >0.8 do not benefit from percutaneous coronary intervention (PCI). Anesthesia is usually not required for cardiac catheterization, and a sedative (tranquilizer) may be administered if needed.
After the examination
Following the examination, the guide wire and catheter must be removed so that subsequently the puncture site can be closed with the aid of a pressure dressing. When accessing via an arterial vessel, there is a great deal of pressure, so the dressing is weighted down and must remain in place for approximately 6(-12) time. Lifting heavy loads should be avoided for the next 2-3 days.
Possible complications
- Serious (life-threatening or fatal) complications-death, myocardial infarction (heart attack), and apoplexy (stroke) are grouped together as major adverse cardiac and cerebrovascular events (MACCEs). The incidence for these MACCEs in unselected (without precise definition of patient groups) registries is 0.63% to 0.3%, including 0.05% to 0.10% for death, 0.05% to 0.06% for myocardial infarction, and 0.03% for stroke/TIA (transient ischemic attack).
- Moderately Severe Complications-This group of complications includes coronary vascular occlusion (air or thrombus), left ventricular decompensation, peripheral vascular complications, hemorrhage requiring transfusion, pulmonary embolism, and anaphylactic shock.
Further notes
- Cardiac computed tomography (cardiac CT) avoided six of seven cardiac catheterization examinations in patients with chest pain or atypical angina (chest tightness, heart pain) in a randomized trial with no increased incidence of cardiovascular disease in the first 3 years afterward. There was no significant difference for a MACE event (“major adverse cardiovascular event”; defined here as apoplexy (stroke), myocardial infarction (heart attack), cardiac death, unstable angina, or revascularization) when comparing the cardio-CT group and the cardiac catheterization patients.
