Coronary reserve

A coronary reserve is the difference between the blood flow in the coronary arteries at rest and the maximum possible coronary blood flow through dilatation of the vessels. The coronary reserve represents the maximum possible oxygen supply for the heart (Herold 2019). The standard value is > 4 (Pinger 2019)

There are several conditions where the coronary reserve may be reduced, such as:

in patients with

• hypertensive microangiopathy (the limitation of the coronary reserve is the main feature [Pinger 2019]).
• Coronary heart disease: In places where there is significant stenosis, the coronary reserve distal to the stenosis decreases continuously (Herold 2019) and can be reduced to half of the normal value (Hombach 2001).
• Microvascular angina (also called syndrome X): Patients with syndrome X complain of angina pectoris attacks. However, the angiographic findings of the coronary system are inconspicuous. In this disease, the coronary reserve may be restricted to a much greater extent than in the other clinical pictures. The causes for this are not completely clear. Blood hyperviscosity or endothelial dysfunction seem to play a role (Hombach 2001).
• hypertrophic obstructive cardiomyopathy (HOCM)
• arterial hypertension

The limitation of the coronary reserve can be demonstrated by the following examination methods:

• absolute quantification of the coronary blood flow with Rb-PET (complex examination [Pinger 2019])
• Argon method (nowadays it is practically only used for scientific purposes) (Hombach 2001)
• intracoronary Doppler flow measurement using a double wire (invasive examination)
• direct measurement in the coronary venous sinus by the thermodilution method (inaccurate results) (Pinger 2019)

An improvement of the coronary reserve can be achieved by reducing the oxygen demand at rest combined with a simultaneous decrease in the resistance of the coronaries (e.g. by nitrates, calcium antagonists, low doses of beta blockers) (Hombach 2001).

The measurement of the coronary reserve has no practical clinical significance today. There is also no therapeutic relevance (Pinger 2019).

1. Herold G et al (2019) Internal Medicine. Herold Publishing House 238
2. Hombach V (2001) Interventional Cardiology, Angiology and Cardiovascular Surgery: Technology, Clinical, Therapy. Schattauer publishing house 35
3. Lapp H et al (2014) The Cardiac Catheter Book: Diagnostic and interventional catheter techniques. Thieme Publishing House 203 - 204
4. Pinger S (2019) Repetitorium Kardiologie: For clinic, practice, specialist examination. German medical publisher. 489
5. Riecker G et al (1993) Clinical Cardiology: Diseases of the heart, circulation and blood vessels near the heart. Springer publishing house 373 - 374