Blood supply of the Heart
The coronary circulation is responsible for nourishing the heart during its tireless effort in pumping blood around the body. This article will highlight the main anatomical points of this arterial and venous systems as well as a common pathological coronary disorder.
Coronary Arteries Anatomy
The first branches that radiate from the ascending aorta, as it emerges from the left ventricle, are the left and right coronary arteries, which directly provide an arterial blood supply to the cardiac muscle. They arise from the bilateral aortic sinuses which are situated just distal to the aortic valve.
Left Coronary Artery
- left atrium
- a large portion of the left ventricle
- a small portion of the right ventricle
- the interventricular septum
- the sinoatrial node in approximately forty percent of the population
Its two main branches consist of:
- the circumflex branch that supplies the posterior surface of the heart by running on its left side within the atrioventricular groove,
- an anterior interventricular branch which runs inferiorly down the interventricular groove to the cardiac apex where it anastomoses with the posterior interventricular artery.
Right Coronary Artery
The right coronary artery passes through the atrioventricular groove to the right side and continues on to the posterior surface of the heart. It supplies:
- the right atrium
- the majority of the right ventricle
- the portion of the left ventricle that communicates with the diaphragm
- areas of the interatrial and interventricular septum
- the sinoatrial node in around sixty percent of the population
- the atrioventricular node in general
This artery further divides into several branches including:
- the sinoatrial nodal branch
- the right marginal branch, which runs to the right margin of the heart
- the atrioventricular nodal branch, which supplies the atrioventricular node at the junction of the four heart chambers within the septae on the posterior side of the heart
- a posterior interventricular branch runs along the posterior interventricular groove.
Cardiac Veins Anatomy
The venous drainage of the heart is primarily governed by the coronary sinus, with the secondary help of the anterior cardiac veins which enter the right atrium directly and the smallest cardiac veins that open directly into the heart chambers. The coronary sinus runs transversely along the posterior surface of the heart in the coronary groove and is a particularly wide vein as it receives blood from:
- the great cardiac vein
- the middle cardiac vein
- the small cardiac veins
- the left marginal vein
- the left posterior ventricular veins
The great cardiac veins run superiorly in the anterior interventricular groove and enter the coronary sinus on the left side. The middle cardiac vein, which is also known as the posterior interventricular vein, follows suit but in the posterior interventricular groove, entering the coronary sinus on the opposing side.
Coronary artery disease is one of the many terms, including ischaemic heart disease or atherosclerotic heart disease, that is used to describe the narrowing of the inner walls of the arteries that supply the heart. This condition is very serious and may prove fatal since it is the most common type of heart disease and the most frequent cause of heart attack.
The most obvious symptom of coronary artery stenosis is angina, or chest pain in the region of the heart which is situated behind the left breast bone. Risk factors for acquiring this condition include:
- hemostatic factors
- high levels of lipoprotein
- lack of exercise
- alcohol consumption
- low levels of dietary antioxidants
- low hemoglobin levels
- old age
A positive diagnosis is obtained via various cardiac examinations including an exercise ECG, electrocardiography or an ultrasound to name but a few. Preventative measures include a balanced diet with plenty of exercise. Treatment for those already suffering from this ailment include various medications and sometimes surgical intervention.