Critical stenosis

A critical stenosis is a condition in which the minimal further narrowing of an artery leads to a significant reduction in blood flow in the distal vessels. However, the effect of a stenosis is influenced not only by the reduction in area but also by other parameters such as peripheral vascular resistance in the vascular beds and collateral flow (Roskamm 2013).

With regard to coronary stenoses, a distinction is made between:

- Grade I: 25 - 49 %

- Grade II: 50 - 74 % (so-called significant stenosis)

- Grade III: 75 - 99 % (so-called critical stenosis) (Herold 2025)

With regard to aortic valve stenosis, for example, a distinction is made between the following degrees of severity:

- No stenosis: 2.5 - 3.6 cm2 opening area pressure gradient < 16 mmHg

- Mild stenosis: 1.5 - 2.0 cm2 opening area pressure gradient < 50 mmHg

- Moderate stenosis: 1.0 - 1.5 cm2 opening area pressure gradient. 50 - 75 mmHg

- Severe stenosis: < 1 cm2 opening area pressure gradient > 75 mmHg

- Critical stenosis: < 0.75 cm2 opening area pressure gradient >100 mmHg (Sattler 2007)

Critical stenosis is usually caused by arteriosclerotic deposits (Weissleder 2003). 403

Depending on the localization of a critical stenosis, angina attacks, dyspnea, syncope, etc. may occur (Schiergens 2023).

Critical stenosis can be diagnosed by:

• Medical history e.g. AP attacks
• Laboratory e.g. enzyme determination such as troponin
• Resting or exercise ECG
• Echocardiography/exercise echocardiography
• Myocardial perfusion scintigraphy
• Coronary angiography (Schiergens 2023)

Treatment of a critical stenosis consists of re-vascularization, e.g. PTCA, stent, bypass, valve replacement (Schiergens 2023).

1. Herold G et al. (2025) Internal Medicine. Herold Publishing House 238 - 239
2. Kasper D L, Fauci A S, Hauser S L, Longo D L, Jameson J L, Loscalzo J et al. (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education 201
3. Roskamm H (2013) Handbook of Internal Medicine: Coronary Diseases.Springer Verlag Berlin / Heidelberg / New York / Tokyo 98
4. Sattler (2007) Fallbuch Kardiologie und Angiologie: 55 Fälle aktiv bearbeiten. Georg Thieme Verlag Stuttgart 10
5. Schiergens T (2023) Surgery. Elsevier Urban and Fischer Publishers 67 - 69
6. Weissleder R, Rieumont M J, Wittenberg J (2003) Compendium of diagnostic imaging. Springer Verlag Vienna 403