As we age, there are two distinct organs that we tend to worry about whether they are going to keep up with or cause us problems as we go along. One of these is the heart. With heart disease being the leading cause of death in the U.S. and one person dying of heart disease every 34 seconds, there is a real reason behind our concern. Before we start learning about different things we can do for our heart in our anti-aging quest, let’s learn a little more about the heart itself.
The Heartbeat of Our Lives
The human heart is a pure muscular Terminator. Once it starts, it never stops. It will carry on beating for your whole life time, day in and day out, until you die or it is damaged. This defines it as a myogenic muscular organ. We never have to think about how to get our hearts to beat, this striated cardiac muscle does it all involuntarily, through signals from the brain
Our wonderful heart starts beating at only 3 weeks after conception occurs and synchronizes itself with the mother. Now it is beating at about 80 beats per minute. Over the next 6-7 weeks it gradually increases to about 170 beats per minute, before finally decreasing and settling at 150 BPM by the 15th week. At this fetal stage there is actually a hole between the 2 ventricles of the heart as well. It seals when the baby takes its first breath. However in about 1 in 5 cases it fails to do so, leading to a ‘Hole in the Heart’ as it is commonly know
The human heart sits in the center of the chest but slightly to the left side, protected by the sternum of the ribcage. The cavity in which it sits is called the Pericardium, a double walled sac which fixes the heart to all of the structures around it and prevents blood overfilling the heart and expanding it too greatly.
The Heart is All Muscle
As stated the heart is a muscular pump. It is the only striated muscle in the body. It has three distinct layers.
The Endocardium is the inner layer interacting with the blood inside the heart. The Myocardium is next out and this layer carries out the contractions that power the heart. The Epicardium on the outside helps form the inner wall of the Pericardium.
The Structure of the Heart
Despite its complex beat sequence and vital function, the heart is a relatively simple organ in its construction. It has 4 distinct chambers consisting of 2 atria and 2 ventricles and a serious of valves.
These two chambers sit at the top of the heart, one on each side and are known as ‘receiving chambers’. This is because they receive the blood as it enters the heart, whether oxygenated or de-oxygenated.
The left atrium deals with blood full of oxygen, received from the lungs via the pulmonary artery, while the right atrium collects the blood without oxygen in any amount, from the Vena Cava ready to pump it around to the lungs again.
The ventricles sit below the atria and perform the contractions to send the blood out of the heart around the body. The left ventricle is the most powerful and sends blood flying around the body via the aorta, full of vital oxygen.
You will often see people feel for their heartbeat on the left side of their chest, even though it is in the center. This is due to the strength of the left ventricle contraction.
The left ventricle forces its contents out towards the lungs to recharge the oxygen in the hemoglobin.
The heart has a series of valves, whose sole purpose is to make sure that the blood only flows one way. There are four in total, being 2 atrioventricular valves and 2 semilunar valves. The valves open and close depending on the differential pressure in play at the time in that part of the beat cycle.
The atrioventricular valves sit between the atria and the ventricles and specifically are called the mitral and tricuspid valves. The tricuspid is usually a three leaf valve, although it can be 2 or four sometimes. The mitral valve has two leaves usually.
The semilunar valves on the other hand are located on the blood vessels where blood leaves the heart. These are the aortic and pulmonary valves, which have two leaves.
Occasionally the valves in the heart may fail or not function properly due to disease. It is known as regurgitation, the blood flowing in the wrong direction.
The tricuspid valve is susceptible to this from rheumatic fever. When this occurs, the tricuspid valve suffers tricuspid stenosis or tricuspid regurgitation. There can also be congenital abnormalities, such as Ebstein’s Abnormality which also cause this.
Medicine today does allow valve replacement and this tricuspid valve replacement was first successfully achieved by the Cleveland Clinic.
How the Heart Beats
The heart is powered by the pacemaker cells or nodes as they are known. They receive an electrical impulse from the brain to start once only and then work independently to set up the beat rhythm which lasts a life time. The various nodes and parts of the internal electrical nervous pathways of the heart each perform specific functions.
The Sinoatrial node is what we know as the ‘pacemakers’. They are located in the right atrium and are a set of highly specialized cells. They commence the impulse required and transmit it through a serious of nerves in the atria and cause them to contract and pump blood into the ventricles below. The node continues to fire regularly, setting the rhythm and pace of contractions, unless instructed by the brain to change it.
The atrioventricular node is located bang in the middle of our hearts in between the chambers of the atria and ventricles. Like a gatekeeper or night club bouncer it monitors the impulse which passes through it from the atrial contractions. In doing so, it slows it down. The effect of this is that it allows the atrium above each ventricle to contract and thus close the cuspid valves before the ventricles contract
The final piece in a heartbeat is the His-Purkinje Network, which is a cluster pathway of special fibers. It transmits and carries the signal out into the muscles of the walls of the ventricles and forces contractions, delivering the blood out into the arterial system of the body
The Heart & Aging
Aging will affect our bodies in different ways, but generally there are some commonalities to the effects on the heart of aging.
It has been shown now that the heart wall starts to thicken as we get older. This is particularly prevalent in the left ventricle which reduces the capacity. On top of that, the left atrium appears to increase in capacity and the mitral valve between the two closes slower, meaning that it fills slower. This was clear by a study at the National Institute of Aging, carried out by Gary Gerstenblith, MD.
The pacemaker, the SA node, will also start to lose some of its cells as it ages. The result is that the heart beat rate may slow down gradually
The overall effect of these 2 changes is that the ability and capacity to cope with rapid and vigorous activity or exercise will decrease by up to 50% by the time we reach 80.
Additional effects include abnormal rhythms, for example atrial fibrillation, degeneration of muscle cells and the stiffening of the heart valves which may cause a murmur. Some of the effects may also be caused or hastened by diseases.
Diseases and Disorders of the Heart
The heart can be susceptible to various disorders and diseases, many of which are triggered, caused or worsened by poor lifestyle, such as alcohol consumption, eating habits, and smoking.
Many things which affect the heart actually are caused by problems in the arterial and venal system outside of the organ itself. But there are significant risks and challenges from the main diseases that do directly affect the heart and which may lead to a ‘heart attack’. A heart attack, or myocardial infarction, is when oxygen is stopped from feeding the heart muscles by damage of blockages to the arteries supplying it with blood.
Angina is caused by a significant temporary lack of flow of oxygenated blood to the heart. Symptoms include breath shortness and mild pains to the chest. Major attacks can also occur, which may lead to heart attack and death.
Arteriosclerosis is perhaps one of the most common problems in western society. The arteries are narrowed by deposits of plaque, which can eventually block them and causes a heart attack. This hardening of the arteries is closely associated with smoking among other things. This will often lead to coronary artery disease.
Other problems directly or indirectly affecting the heart include aortic stenosis, congestive heart failure in old age, and deep vein thrombosis.
With heart disease in one form or another being the leading cause of death, we surely want to focus our attention on the things we can do to improve our heart health and reduce our risks.