The heart is a hollow muscular organ that pumps blood through our blood vessels delivering oxygen and nutrients to our tissues and organs. The average adult heart beats 72 times a minute; 100,000 times a day; 3,600,000 times a year; and 2.5 billion times during a lifetime. The heart pumps blood to almost all of the body’s 75 trillion cells.
The heart is located in chest midline, slightly moved to the left side. It is a strong muscular organ and during an average lifetime, the heart will pump nearly 1.5 million barrels of blood—enough to fill 200 train tank cars. The volume of blood pumped by the heart can vary over a wide range, from five to 30 litters per minute. Myocardium is supplied with blood via coronary arteries that came from aorta, just above the aortic valve.
A woman’s heart typically beats faster than a man’s. The heart of an average man beats approximately 70 times a minute, whereas the average woman has a heart rate of 78 beats per minute.
Venous blood returns from the body, and enters the right atrium via superior and inferior vena cava. Right atrium fills the right ventricle that pumps the blood through pulmonary circulation thereafter. Oxygenated blood from lung, fills the left atrium, and left ventricle. Left ventricle is a strong muscular pump that ejects oxygenated blood through the aorta. The heart pumps oxygenated blood through the aorta (the largest artery) at about 1 mile (1.6 km) per hour. By the time blood reaches the capillaries, it is moving at around 43 inches (109 cm) per hour.
Left ventricle is much stronger than the right one, because of higher pressure that generate and more work that exerts, and is therefore much thicker.
Aortic valve is a tri-leaflet fibrotic tissue structure located between the left ventricle and the aorta. During the left ventricle contraction – systole, aortic valve opens while closes during left ventricle relaxation - diastole. When closed, aortic valve stops blood return to the heart and that way provides one-way blood flow through the aorta.
Mitral valve is a complex structure located between left atrium and left ventricle. Mitral valve prevents retrograde blood flow to the left atrium during systole and provide optimal left ventricle filling during the cardiac cycle.
Pulmonary and tricuspid valve are “right heart” valves that corresponds to aortic and tricuspid valve respectively. Pulmonary valve has the same structure as an aortic, while tricuspid valve has three cusps when compared to mitral. Otherwise they function in the same way as “left-side “valves.
Aorta is the largest arterial blood vessel. It takes blood from the heart to limb, head and visceral arteries. Cardiac surgery takes care of its chest portion called thoracic aorta that is made of ascending, arch and descending aorta. Ascending aorta begins with aortic valve, while branches for head and arms arise from aortic loop called aortic arch at upper chest level. Descending aorta goes down to the diaphragm after the arch, where abdominal aorta begins.
Arrow is pointing the three leaflet structure of aortic valve.
Coronary arteries came from ascending aorta just above the aortic valve. Left coronary artery supplies with blood almost 70% of myocardium. After a short common trunk, called left main stem, it divides in left anterior descendent (LAD) and circumflex artery. LAD brings blood to most important contractile areas of the left ventricle. Right coronary artery vascularizes inferior interventricular septum in almost 80% of cases.
Contrast injection into coronary ostia gives an X-ray visible image of coronary arteries – coronarography. This is a diagnostic procedure used to examine presence of coronary blockage, and to make plans for further revascularisation treatment.
In 1929, German surgeon Werner Forssmann (1904-1979) examined the inside of his own heart by threading a catheter into his arm vein and pushing it 20 inches and into his heart, inventing cardiac catheterization, a now common procedure.
The right atrium holds about 3.5 tablespoons of blood. The right ventricle holds slightly more than a quarter cup of blood. The left atrium holds the same amount of blood as the right, but its walls are three times thicker.