A Love Letter to Your Heart
Please come on a journey with me to learn about the most beautiful, moving work of art in our body.
For most of us, our heart is the last organ to stop. All of our other organs can fail for any number of reasons, and the heart keeps on ticking, even when it has taken a licking.
On Valentine's Day, I invite you to put your hand on your chest and thank your heart. While every cell and organ in your body is vital, we cannot live without our heart when it pauses for more than a few seconds.
If you live to 80, your heart will have beaten over 3 billion times.
The heart is an organ of incredible power and endurance. It is a muscle. It is an electrical system. It has intricate and amazing plumbing. All work in perfect harmony.
A healthy heart is the size of your relaxed fist and sits very slightly to the left of the center of your chest. The apex (the point at the bottom) is tilted slightly upward.
Try this: close your left hand into a relaxed fist, put your thumb against your breastbone (sternum), thumbnail toward your chin, with your knuckles pointing to the right side of your chest, pull your little finger knuckle upward – and that is how your heart is lying behind your ribs.)
The heart looks simple: it is an elegant muscle containing four chambers with two atrium at the top and two ventricles at the bottom. It has plumbing coming in and plumbing going out. With its beauty and seeming simplicity, there is a reason it has always been seen as the seat of the soul.
“Using precise physiological measurements, we can detect that the heart is creating emotion as well as responding to it.” Sean Harding, The Exquisite Machine
The heart and the lungs are literally in perfect rhythm: when the heart stops, the lungs will quickly stop. If the lungs stop, the heart will follow within seconds. When your heart stops, your brain cells will begin to die within three to five minutes. Your other vital organs quickly follow suit.
The heart has several separate functions that all work together:
The Plumbing: the Arteries and Veins
The Mechanical System: the Chambers, Muscle and Valves
The Electrical System: the Natural Pacemaker and Conduction Nerves.
The Plumbing: the Arteries and Veins
Blockage of the coronary arteries is likely the type of heart disease you are most aware of. Knowing how your heart arteries work will empower you to reduce your risk of a future heart event and know what your specialists are talking to you about should you need medical or surgical intervention.
Veins are the vessels that transport deoxygenated blood (blood without oxygen) from the body to the heart. Blood comes from the body via the inferior and superior vena cava – the largest veins in our body – and into the right atrium upper chamber, pushed to your right ventricle, and then pushed to your lungs to be oxygenated.
Arteries are the vessels that leave the heart and transport oxygenated blood to the rest of the body. Blood from your lungs moves into the left atrium, pushed into the left ventricle, and then pushed to your heart muscle itself, then to your brain and to your body via the mighty Aorta – the largest artery in your body, bigger in circumference than a standard garden hose. The aorta carries oxygenated blood from the heart to the heart itself, the brain, and the body.
The Coronary Arteries
The heart consumes more oxygen than any other organ. Blood moving through the heart chambers does not supply the heart with blood and oxygen; the heart needs its own arteries. The aorta comes out of the left ventricle, and several immediate arteries come off of it. The first one goes to the heart muscle. The subdividing arteries have a trunk and branches resembling an upside-down oak tree.
*When an artery becomes blocked, the heart muscle beyond the blockage begins to die. This is a heart attack or myocardial infarction.
The Mechanical System: the Chambers, Muscle and Valves
The Heart’s Chambers
The chambers at the top of the heart are called the Atrium.
The Right Atrium chamber collects deoxygenated blood from the entire body and sends it to the Right Ventricle through the Tricuspid Valve. Its muscular wall holds the SA Node, the heart's natural pacemaker, and the conduction nerve to the ventricles.
The Left Atrium chamber collects blood from the lungs and sends it to the left ventricle via the mitral valve.
*The most common electrical disease is Atrial Fibrillation, commonly known as AFib, where the atrium no longer contracts regularly and merely ‘wiggles’ or fibrillates. Undiagnosed and untreated atrial fibrillation is the leading cause of strokes.
There are two chambers at the bottom of the heart called the Ventricles.
The Right Atrium collects blood from the body and sends it to the right ventricle and then to the lungs.
The Left Atrium chamber collects blood from the lungs, sends it to the left ventricle, which then and sends blood to the heart muscle, brain, and body.
*Ventricular Tachycardia (VTach) or Fibrillation (VFib) occurs when the ventricles start beating so rapidly and in such an uncoordinated way that they cannot fill with enough blood to push to the lungs, heart, brain, and body. This rhythm is fatal unless immediately reversed with electrical defibrillation to put the heart back in a coordinated rhythm.
The Valves
All valves open during the beat to allow blood to flow to the ventricle, lungs, or body and then close so that the blood cannot flow backward. When you hear Lub-Dub through a stethoscope, the Lub is the closing of the valves between the atrium and ventricles. The Dub is the closing of the valves between the ventricles and the lungs and body.
The tricuspid valve separates the right atrium and right ventricle. As its name suggests, it has three leaflets. Because it experiences fairly low pressures, it rarely fails.
Mitral Valve: sits between the left atrium and the left ventricle. It has two leaflets, so it is called bicuspid. It experiences high pressures and is the second most likely valve to fail.
Pulmonary Valve: separates the right ventricle from the pulmonary artery, taking deoxygenated blood to the lungs. Like the Tricuspid Valve, pressures are usually low, so it rarely fails.
Aortic Valve: this amazing valve is under incredible pressure. It separates the left ventricle from the aorta. It has three leaflets or cusps (tricuspid) that open to let blood flow to the body. Because of the immense pressure, it is most likely to fail, and blood regurgitates back into the heart (causing cardiomyopathy or enlargement of the heart) and causes a lack of oxygen in the body. It is the most likely valve to be replaced.
The Cardiac Muscle
You have billions of cells called cardiomyocytes (card-ee-oh-my-oh-cites) that are pure miracles. They are the only cells in the human body that are not replaced; over half of the same cells that were present when you were born are the same cells you have when you die. They rarely become cancerous, but they are very susceptible to damage from chemicals, particularly chemotherapy. They sense and respond to oxygen and hormone levels almost instantly. Given the right conditions, they can continue to beat on their own without nervous system intervention, allowing a heart transplant. Each and every cell is electrical, and the vast majority of the time, those billions of parts work in perfect synchronicity.
The right side of the heart has a lower pressure load than the left and is, therefore, not as large.
*Because heart cells are not replaced, the muscle cannot heal itself after a heart attack, bacterial or viral infections, or toxic damage. This results in cardiomegaly (card-ee-oh-meg-ah-lee), otherwise known as enlargement of the muscle. The heart can no longer receive enough blood, or push enough blood to the body, which is commonly referred to as heart failure. Left-sided heart failure is much more common than right-sided failure.
The Electrical System: Natural Pacemaker and Conduction Nerves
As stated above, every heart cell is electrical, but they nearly always take orders from the heart's pacemaker, the SA Node above the right atrium to the AV Node in the right atrium, where a signal is sent to the ventricles via the central muscular wall.
ECGs show the conduction and route of electrical signals. If there is any heart damage or scarring, it slows or inhibits the signals, and that can be seen in the ECG readings, allowing the diagnosis of past and present heart disease.
“The right and left ventricular circuits take place in synchronicity with each other in every heartbeat. Blood volumes going through the two circuits must be precisely matched, as even tiny differences would add up very quickly to unbalance the system. As the blood leaves them, each of the chambers of the heart relaxes, ready to receive the new load. The heartbeat is over, and that move movement of the symphony is complete.” Sean Harding, The Exquisite Machine
We Can Help
Connie Jorsvik is an expert at navigating the BC cardiac healthcare system. She finds lost referrals and helps patients get appointments much more quickly than would otherwise be possible. If you've been told you have any type of heart condition, please reach out. She might help you save precious months and maybe even your life.
Sources and Resources
How Blood Flows through the Heart: NIH (National Institutes of Health)
How a Healthy Heart Works: Heart and Stroke Foundation
The Exquisite Machine: Sean E. Harding
