Coronary Angiography

Coronary angiography is a diagnostic procedure in radiology and cardiology that can be used to visualize the coronary arteries (arteries that surround the heart in a wreath shape and supply blood to the heart muscle) using contrast media as an angiographic method to evaluate coronary artery disease (CAD). Invasive coronary angiography is performed during cardiac catheterization via the right or left femoral artery. It allows detection of stenosis (narrowing) or complete vessel occlusion, which can be treated in the same session by PTCA (Percutaneous Transluminal Coronary Angioplasty; percutaneous coronary intervention, PCI; Procedure to dilate stenosed (narrowed) or completely occluded coronaries (arteries that surround the heart in a coronary shape and supply blood to the heart muscle) (= revascularization; revascularization)) and stent implantation (insertion and deployment of a stent (vascular support) using a balloon catheter).

Indication (indications for use)

  • Acute coronary syndrome – In a diagnostically confirmed or a diagnostically probable acute coronary syndrome (ACS; acute coronary syndrome; spectrum of cardiovascular disease ranging from unstable angina pectoris (UA; “chest tightness”; sudden onset of pain in the cardiac region; here: Form of angina whose symptomatology is not constant but changes) to the two main forms of myocardial infarction (heart attack), non-ST elevation myocardial infarction (NSTEMI) and ST elevation myocardial infarction (STEMI)), coronary angiography is the procedure of choice for assessing coronary vessel blood flow, with parallel therapeutic dilatation (widening) of the vessel stenosis, if necessary. Indications for performing coronary angiography in acute coronary syndrome include failure of conservative symptom control and unstable angina, as well as in high-risk patients with abnormal previous examinations on exercise ECG or stress echocardiography. The procedure is also of great importance in the evaluation of acute and chronic occlusions of coronary arteries in terms of myocardial infarction (heart attack) or occlusion of bypass vessels (bypass vessels) and stent stenoses (occlusion of vascular bridges). However, coronary angiography is not a “screening” method for coronary artery disease in asymptomatic patients.
  • Patients with high-grade suspicion of stenosing CAD after noninvasive diagnostics who are willing to undergo bypass surgery for prognostic indication after counseling with the patient information leaflet “Suspicion of coronary artery disease: do I need a cardiac catheterization?” should be recommended invasive coronary angiography [see S 3 guideline below].
  • Patients with high-grade suspicion of stenosing CAD after noninvasive diagnosis in whom symptoms persist despite optimal conservative therapy (symptomatic indication) should be offered invasive coronary angiography.

Contraindications

Absolute contraindications

  • No therapeutic consequence in case of pathologic findings – In case of patient’s unwillingness to undergo revascularizing therapy (balloon dilatation/expansion of a stenosed vessel segment with the help of a balloon catheter and stent implantation/insertion of vascular bridges or bypass surgery/operation to bridge coronary vessels e.g. E.g., by veins) or patients with comorbidities (concomitant diseases) in whom the risk of coronary angiography is greater than the benefit by securing the diagnosis, coronary angiography should not be performed.

Relative contraindications

  • Elevated serum potassium level-Coronary angiography should not be performed if a severely elevated potassium level is measured in the patient’s serum.
  • 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 necessary, the test should be omitted if the serum level of digitalis is significantly elevated.
  • 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.
  • Hypertensive crisis – if there is a massive increase in blood pressure, the risk of the examination may exceed the benefit, so the procedure can be used only in isolated cases.
  • Renal insufficiency (renal impairment) – in renal insufficiency, contrast administration may further reduce renal function. Intravenous administration of fluids before and after the examination may reduce the damage. However, the benefit of acetylcysteine (ACC) administration in reducing renal injury is controversial.
  • Contrast agent allergy – If the patient is allergic to the contrast agent, there is a risk of anaphylactic shock, based on 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. Depending on the clinical picture, further preliminary examinations must take place.
  • Laboratory diagnostics – In particular, the parameters hemoglobin (anemia diagnostics / anemia), TSH (thyroid value) and creatinine (kidney value) should be determined. Inflammation parameters (CRP) and coagulation parameters (Quick, PTT) are also usually required.

The procedure

Coronary angiography is performed during cardiac catheterization via the right or left femoral artery (large femoral artery), the right or left radial artery (brachial artery), or the right or left brachial artery (brachial artery). Typically, puncture of the respective access vessel is performed using a modified “seldinger technique,” in which direct puncture of the artery is used without piercing the vessel’s posterior wall. To prevent major damage to the artery, a sheath is usually inserted into the access vessel. Radiological imaging of the coronary vessels using contrast medium is followed by a procedure that depends on the findings: If the findings are unremarkable, the catheter is withdrawn; if the stenosis exceeds 70% of the lumen (interior of the vessel) of the coronary artery, an inflatable balloon is used to dilate (expand; balloon dilatation) the stenosis via a guide wire, and a stent insertion (vessel support) is performed. Such coronary intervention is required in less than half of coronary angiographies.

After the examination

Following the examination, the guidewire and catheter must be removed so that the puncture site can subsequently be closed with the use of a pressure dressing. When accessing via an arterial vessel, there is a great deal of pressure, so the dressing must be weighted down and remain in place for a defined period of time.

Possible complications

  • Bleeding at the injection site
  • Contrast agent intolerance
  • Cardiac decompensation (acute heart failure/heart failure).
  • Cardiac arrhythmias
  • Cholesterol embolism syndrome – occlusion of small arteries by wash-in (embolism) of cholesterol crystals from ruptured (ulcerated) atherosclerotic plaques.
  • Myocardial infarction (heart attack)

Other notes

  • Cardiomyocyte injury occurs more frequently than suspected after coronary angiography: using high-sensitivity measurement of cardiac troponin (hs-cTnT), myocardial injury was detected in 13, 5% of patients after angiography.
  • The number of purely diagnostic coronary angiographies can be greatly reduced by means of estimation of fractional flow reserve (FFR = ratio that provides an indication of how much a stenosis (narrowing) restricts blood flow in the coronary vessel (heart vessel); gold standard for analysis of coronary stenosis) by multislice CT scans (FFR-CT).FFR indicates the ratio of mean blood pressure distal to the stenosis (narrowing) to mean aortic pressure.
  • A cardio-MRI study of NSTEMI patients (myocardial infarction/heart attack in which there is no prolonged ST elevation on ECG, i.e., the typical signs of infarction) after coronary angiography demonstrated that interventional cardiologists failed to reliably identify an infarct vessel by coronary angiography in 37% of patients with NSTEMI-typical symptoms and troponin progression; in 6 of 10 of these patients, cardiac MRI was able to demonstrate the vessel; in 2 more of 10 of the patients without coronary angiographic evidence of an infarct vessel, MRI was able to make a nonischemic, cardiac diagnosis that could explain the symptoms and troponin progression.