Heart is the muscular organ which is very much essential for human survival as it constantly pumps and supplies oxygenated blood to tissues and collects deoxygenated blood from tissues and sends it to the lungs for the purpose of purification. For the proper functioning of the heart, the inevitable element is oxygen that is supplied to the heart by the blood through the coronary circulatory system.
The coronary system comprises of coronary arteries and coronary veins. The coronary arteries are further divided into left coronary artery and right coronary artery and they originate at the coronary ostium, which is seen at the apex of aorta, the largest artery in the circulatory system. The coronary arteries supply oxygenated blood to the heart tissue.
The coronary veins are also divided into right coronary vein and left coronary vein. These coronary veins carry deoxygenated blood from the heart to the lungs. These veins receive deoxygenated blood from cardiac veins,namely; left marginal vein and left posterior ventricular vein. Thus coronary circulation basically maintains the oxygen supply and demand in the right proportion so that efficiency of the hearts’s pumping can be maintained.
The coronary arteries and the arterioles forms the microvascular network that are involved in microcirculation which are the principal sites for the vascular resistance and regulates the proper flow of blood. The vascular resistance is low in the coronary arteries.
The coronary circulation plays a very important role in coupling the blood flow with the oxygen demand. When the cardiac tissue requires more oxygen, the coronary blood circulation in the heart appropriately increases to meet the oxygen demand. Moreover, according to the changes in the aortic pressure, the pressure in the coronary circulation changes, and in order to maintain the normal coronary flow of blood, the perfusion pressure must be auto regulated between 60 and 200mm Hg. Adenosine and nitric oxide are considered to be involved in autoregulation.
The coronary blood circulation can also be enhanced by vasodilator metabolites like beta-adrenoreceptors which are responsible for the norepinephrine induced vasodilation of the blood vessels that supply blood to the myocardium.
If there is any defect in the coronary arteries or if there is a blockage in the circulation, the flow of blood to the heart may be greatly affected and results in a condition called tissue hypoxia. This condition can be reverted back by placing a stent to dilate the lumen of blood vessels or by using the intra coronary angioplasty balloon. If blood flow is hampered by means of blood clots, then thrombolytic drugs are used to remove the clot for proper circulation. Anti-platelet drugs and aspirin are usually given to avoid the formation of a blood clot later on. The non-coronary circulation is also essential for the proper blood flow and helps to meet the oxygen demand of the heart.