Heart, the symbol of love, of Valentine’s Day, even of religious adoration, is always fascinating but still a mystery to most of us. The amazing facts about our most loyal and dedicated heart are mind-boggling and a constant source of wonderment. Winning hearts, stealing hearts, breaking hearts, and for us cardiac surgeons, mending hearts, are easier to understand and do, than to comprehend fully the wonders of this hard-working, ceaselessly pumping, untiring, and unique muscle in our body.
How large is our heart?
The size of the adult heart is about the volume of two hands clasping each other, with the fingers intertwined. In children, it is the size of the kid’s one fist. The heart is located, not to the left, as often thought of, but in the middle of your mid chest, enclosed in its own compartment, an envelope called pericardial sac, and located between the left and right chest cavity, where the left and right lungs are, respectively. Its tip is pointed slightly to the left.
Does the heart ever rest?
The heart beats about an average of 70 beats per minute, 4,200 an hour or about 100,800 times in one day, roughly about 36 million times in a year. In an average life span, the human heart will beat about 2.5 billion times. But contrary to what seems obvious, the heart rests for a split second in between beats. This happens between contractions, when the heart relaxes to accept more oxygenated blood from the lungs, and prepares to pump blood out of its chambers again.
How powerful is the heart contraction?
The heart contraction is so powerful that it approximates the force one needs to give a tennis ball a hard and full squeeze with all your might. The cardiac muscles work twice as hard as the leg muscles of a person running full speed. The hydraulic force generated is necessary to propel rapidly the blood that circulates about 13 kilometers per minute, or 780 kilometers per hour, about four times the speed of the fastest racing car there is.
Will an isolated heart beat on its own?
The muscle of the heart is a specialized one that beats on its own (automaticity) and one that has its own rhythm (rhythmicity), even when cut off from the body and lying on a surface. The isolated heart in this situation will beat continuously until its own residual energy is used up, which is within about 4 minutes. It then ceases movement.
What is the normal heart rate?
This varies from individual to individual, depending on the age, condition of the body, and the health of the person. A well-conditioned athlete may have a heart rate of 35 a minute and feel great, but this rate would cause almost all of us, non-athletes, to feel faint and pass out, or in the very least, feel very dizzy and weak. On the average though, the normal resting rate (medically speaking) is from 60 to 100 beats per minute. Anything below 60 is called bradycardia (too slow heart rate), and a rate higher than 100 is tachycardia (too fast a heart rate). Among children the range is between 90-120 beats a minute.
How much blood does a person have?
The adult human body has about 5.6 liters (6 quarts) of blood in the circulation. These 6 quarts completes a full round of circulation throughout the body about every 20 seconds. The blood travels a total of about 19,000 kilometers (12,000 miles) in 24 hours, which is about four times the distance from California to New York, or roughly five times the air miles from San Francisco to Manila. About one million barrels of blood is pumped by the heart in an average life span, a volume enough to fill more than three super tankers.
Where does the blood go?
The blood pumped by the heart goes out through the ascending aorta, the largest artery in the body (about half the size of an average wrist), that is connected to the heart, and circulates through the various arterial branches and capillaries to the brain and to all other vital organs (liver, pancreas, kidneys, adrenals, intestines, sex organs, etc.). The capillaries are terminal or end arteries, the size of which is about one-tenth the size of the human hair. These are the tiny vessels that actually bring blood to the tissues and cells of the various parts of the body.
How does blood get oxygen and nutrition?
The nutrition and oxygen in the blood are used up by the tissues and cells. The used blood (now containing much less oxygen and more carbon dioxide, lactic acid and other “waste products”) travels back from the tissues and cells to lungs for oxygenation. Then blood goes to the heart for pumping to all organs, like the liver where toxins will be detoxified, to the kidneys that will filter the waste products and passed out through the urine, to the stomach and intestines where it will be replenished with new nutrition. The used blood then flows back to the lungs. After the oxygenation, the blood flows into the heart, ready to be pumped back into the circulation once again. And the cycle goes on.
How strong is our heart?
A healthy heart can take a lot of beating (no pun intended). It is one of the most powerful pumps in the world, even when compared to the mechanical ones built by man. Self-contained, self-propelled, energy-efficient, the heart works without stopping, and can survive grave insults and abuses we, humans, subject it to day in and day out.
Is mechanical heart better?
Certainly not. Not yet, anyway. The man-made hydraulic-driven artificial or mechanical heart prosthesis available today is still no match to the one we were born with. Besides being a bulky foreign body and made of hardware not as soft and tender as our body tissues, it also requires electrical energy from outside the body and the use of anticoagulants to prevent thrombosis (blood clots, which can cause stroke). The mechanical heart is also prone to infection and not as durable as a natural heart. At the present, the artificial heart leaves too much to be desired.
When is artificial heart used?
Mechanical heart is helpful as a bridge to heart transplantation, implanted temporarily (for a few weeks or so) while a transplant patient waits for a human donor heart, but not as a long-term, permanent, heart replacement. Obviously, of course, a suitable permanent mechanical heart with as close inherent features as those of the human heart is the ultimate goal of ongoing researches around the world. When that day comes, a dying cardiac patient would not have to wait for a compatible donor to die before getting heart transplant. The cardiac surgeon then would simply ask the operating room nurse for the appropriate size artificial heart from the shelves (much like asking for a pacemaker today) to be implanted on the patient. By then too, coronary bypass, heart valve surgery, and most cardiac surgeries, would be a thing of the past, and the millions of lives lost annually around the globe today from severe and end-stage heart diseases would be saved. As a cardiac surgeon, I can’t wait for that dream to come true.
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Philip S. Chua, MD, FACS, FPCS, Cardiac Surgeon Emeritus in Northwest Indiana and chairman of cardiac surgery from 1997 to 2010 at Cebu Doctors University Hospital, where he holds the title of Physician Emeritus in Surgery, is based in Las Vegas, Nevada. He is a Fellow of the American College of Surgeons, the Philippine College of Surgeons, and the Denton A. Cooley Cardiovascular Surgical Society. He is the chairman of the Filipino United Network – USA, a 501(c)(3) humanitarian foundation in the United States. Email: [email protected]
