The formation of collateral circulation requires three conditions, i.e., there must be enough anastomotic branches between the original vessels, the speed of vessel obstruction is slow, and the anastomotic branch vessels are normal.
1. There must be enough anastomotic branches between the original blood vessels: mesenteric artery has many anastomotic branches and it is easy to establish collateral circulation. The venous system is rich in anastomotic branches, and it is easy to establish collateral circulation after obstruction. However, the anastomotic branches of the inferior vena cava are also fewer and it is not easy to establish collateral circulation.
2. The speed of vascular obstruction is slow: when portal vein thrombosis occurs, the speed of vascular obstruction is fast, and then the collateral circulation often cannot be established in time adequately.
3. Normal anastomotic vessels: when coronary artery atherosclerosis causes local myocardial ischemia, if the anastomotic vessels have the same atherosclerotic lesions, then the collateral circulation is not easy to establish effectively.
Patients should consult the doctor in time when they are in discomfort, so as not to jeopardize their lives.