Noncoronary Collateral Myocardial Blood Flow: The Human Heart’s Forgotten Blood Supply

Abstract

The “noncoronary collateral circulation” (NCCC) or “noncoronary collateral myocardial blood flow” (NCCMBF), reaches the heart through a micro-vascular network arising from the bronchial, esophageal, pericardial, diaphragmatic, and aortic arteries. The left and right internal thoracic arteries (ITAs) along with their collateral branches also serve as a source of NCCMBF-a feature seen in other mammals. Under certain circumstances the ITAs have a high potential for developing collateral branches. In the case of severe Leriche syndrome or with chronic obstruction of the abdominal aorta, the ITAs can serve as the main or even sole source of blood supply to the lower limbs. It is also possible for the ITAs to develop angiographically visible branches that directly connect with the coronary arteries. In ischemic conditions there is a functional, ischemia-reducing extracardiac coronary artery supply via natural ipsilateral ITA anastomosis. To date we know little about NCCMBF and its potential benefits in clinical applications, which makes this a challenging and intriguing field of research. This paper reviews all available data on noncoronary collateral blood supply to the human heart.

The Human Coronary Collateral Circulation, Its Extracardiac Anastomoses and Their Therapeutic Promotion

“…Apart from inter-coronary arterial anastomoses, the human coronary arterial circulation is supplied by several extracardiac anastomoses, also called the non-coronary collateral myocardial blood flow (NCCMBF) [19]. Hence, the heart receives additional blood from the arteries of surrounding structures [20,21,22,23,24].…”

Neoangiogenesis connecting a left internal mammary artery proximal stump to an ischemic area of the heart after bypass occlusion

“…The potential for IMAs to form collateral branches was the basis for the Vineberg operation in the 1940s, in which IMAs, implanted into the left ventricle free wall, lead to a vascular network within the myocardium . Graft occlusion following a CABG also may result in collaterals to the heart . These observations suggest that, under hypoxic conditions or when there is an obstruction to anterograde flow or both, IMAs may exhibit significant plasticity.…”

“…This may consist of new branches or the enlargement of pre‐existing collaterals, scenarios generally seen when ischemia involves the inferior limbs or heart . Besides these rare but naturally‐occurring conditions, iatrogenic/voluntary occlusion of the IMAs may create new collaterals to the heart . Herein, we present a patient who underwent triple coronary artery bypass graft (CABG) surgery with a free‐graft left IMA (LIMA) which occluded after 6 weeks, in whom new angiographically‐visible branches, arising from the proximal stump of the LIMA, led to the ischemic anterior wall of the heart.…”

Therapeutic occlusion of the internal mammary arteries to relieve refractory angina

“…Although results in hundreds of patients were encouraging[ 3 ] and some publications were outstanding, after the start of the cardiopulmonary bypass era, all debate regarding IMA occlusion ceased, and it fell into absolute oblivion for 50 years, until the principle was resurrected for no-option RA patients in 2010. [ 2 ] Apart from the microvascular network studied by previous authors, we now have angiographic evidence that new collaterals can develop from the patent proximal stump of an IMA,[ 4 ] occluded within its mid-distal segment, to reach ischemic heart; and that, sometimes, a branch may join a coronary artery directly. Hence, interventional therapy employing embolization or plug occlusion of an IMA has been proposed.…”