The Rhythm & Flow of Your Heart

Even though the average man or woman only has between approximately 6 to 10 pints of blood in their bodies, the heart pumps the equivalent of 2,000 gallons of blood through its chambers everyday. In order for your heart to meet your body’s blood supply demands, the chambers, the valves and electrical (cardiac conduction) system of your heart have to work in a highly coordinated rhythm. Understanding how blood flows through a healthy heart and how physicians diagnose heart disease will help you to understand the nature of your cardiac disorder.

Valve Function and Blood Flow

As any engineer will tell you, in order for a pump to work sufficiently, there has to be a priming mechanism and there have to be valves that help control directional flow so necessary pressure is created. There are four valves in your heart that regulate the directional flow of blood.

Your heart’s valves contain cusps (flaps) that open to let blood flow through and close to ensure that blood doesn’t regurgitate backwards. Valve stenosis occurs when the cusps don’t open completely, so the opening of the valve is smaller than it should be which can restrict blood flow. Valve regurgitation occurs when the cusps don’t close completely allowing blood to flow backwards. Defective valves can be congenital (present at birth) or they can be damaged by infection, disease, or age. Your physician listens through a stethoscope to assess the health and efficacy of your heart’s valves.

Your heart receives oxygen poor blood from the superior vena cava (a large vein) into the right atrium. The tricuspid valve regulates the flow of oxygen poor blood from the right atrium into the right ventricle. The pulmonary valve regulates directional blood flow from the right ventricle to the pulmonary artery.

Oxygen poor blood travels through the pulmonary artery and on to the lungs where it becomes oxygenated. Oxygenated blood is returned to the left side of the heart into the left atrium through the pulmonary veins. The mitral valve regulates directional blood flow from the left atrium into the left ventricle, and the aortic valve regulates directional blood flow of oxygen rich blood from the left ventricle to the aorta.

The aorta is the largest artery in the human body and it transports oxygen rich blood from the heart to the rest of the circulatory system. The aortic and the pulmonary arteries help to create pressure by resisting the blood flow from the heart as blood is pumped from the ventricles. Your blood pressure is a measurement of that pressure when the heart contracts to pump blood into the arteries (systolic pressure) and when the heart relaxes between contractions (diastolic pressure). Your blood pressure is recorded as systolic over diastolic, a normal, healthy pressure reading being 120/80.

The Cardiac Cycle: Rhythm & Conduction

A single cardiac cycle is the complete sequence of a heartbeat. Each of the events of a heartbeat happens in time and has a beginning, middle and end. The following terms indicate the beginning of each sequence:

Atrial Diastole

As the atria dilate, blood from the superior vena cava flows into the right atrium and blood from the pulmonary veins flows into the left atrium.

Atrial Systole

When both atria contract pumping blood through the valves into the ventricles – when the contraction is complete, the mitral and tricuspid valves shut.

Ventricle Diastole

As the ventricles dilate, their pressure drops below the pressure in the atria causing the tricuspid and mitral valves to open allowing blood to flow into the ventricles.

Ventricle Systole

When both ventricles contract pumping blood through the valves into the arteries – when the contraction is complete,the pulmonary and aortic valves shut.

Complete Cardiac Diastole

The period in which both the atria and ventricles dilate (relax) and the all of the heart valves are closed.

A single heartbeat represents one complete cardiac cycle. When you consider that your heart normally beats 70 times per minute during calm periods of inactivity, your heart completes over 100,000 cardiac cycles per day.

What Keeps the Beat?

The tissue of your heart muscle is highly specialized myogenic muscle tissue, which means it can contract and relax on its own without a nerve impulse. Cells from your heart muscle tissue will beat in unison if placed side by side. In other words, your heart muscle doesn’t need outside stimulus from your brain to keep beating. Your heart’s survival in dire situations is protected because the impulse to contract doesn’t come from outside of itself. But with so many cells and layers of muscle tissue, along with the chambers and valves, something has to coordinate the heart’s rhythm.

Cardiac conduction regulates the rhythms of the cardiac cycle. Atop the right atrium is a bundle of cells called the sinoatrial (SA) node. The SA node is often referred to as your heart’s natural pacemaker because it controls the initiation of electrical impulses in cardiac conduction.

Once an electrical impulse is fired across the SA node, it travels across the right atrium to the left atrium causing the contraction in atrial systole.

The electrical impulse reconvenes at the atrioventricular (AV) node and travels across the atrioventricular bundle (Bundle of His) where it splits down the right and left crura spreading into the Purkinje’s fibers causing the contraction in ventricular systole.

An EKG (or ECG) allows physicians to monitor and measure the timing of the electrical impulses of the cardiac conduction cycle. The measurement of the EKG is recorded as a wave. The wave has three differentiated parts: the P wave, QRS wave (or QRS complex) and the T wave.

Learn more about the signs and symptoms of a heart attack. If you learn the signs of a heart attack and what steps to take, you can save a life – maybe your own.

Heart Attack Warning Signs

Below are the signs and symptoms of a heart attack. Please review them. Should you experience any of these, call 911, or have someone drive you immediately to the hospital. DO NOT DRIVE YOURSELF.

Any one or more of the following could indicate a heart attack.

Chest Discomfort or Pain

• Sudden discomfort or pain in the chest area that lasts longer than 15 minutes.
• The chest area may include the neck or throat, jaw, shoulder, one or both arms or back, especially between the shoulder blades.
• The discomfort or pain may feel like burning, squeezing, heaviness, tightness, or pressure
• Heart attack discomfort or pain may or may not be severe but it typically covers an area that is impossible to cover with one single hand.
• Discomfort or pain that feels like indigestion but encompasses a large area (larger than one hand flattened)
• In women, the discomfort/pain may be more vague

Sudden Shortness of Breath, or Sudden Difficulty Breathing

Nausea and Vomiting

• Nausea and vomiting may occur in some individuals, usually around the time of discomfort/pain episode.

Sweating

• Sweating often occurs at the time of the chest discomfort/pain. Cool, clammy skin is often a feature of profuse sweating. Profuse sweating that accompanies chest pain is a clear indication to seek medical attention immediately.

Chronic thromboembolic pulmonary hypertension (or “chronic pulmonary embolism”) is a dysfunction of the heart’s right ventricle that results from changes to the structure or function of the lungs. Changes to lung structure or function cause increased resistance to blood flow through the lungs which leads to high blood pressure in the lungs and called “pulmonary hypertension.”

What is Chronic Pulmonary Embolism?

The veins in our body carry blood to and from the heart. When blood is returned to the heart it also travels, through the pulmonary arteries, to the lungs where it receives oxygen. The blood then travels away from the heart, carrying the oxygen to other parts of the body.

Sometimes blood clots form within veins, usually in the lower body. Blood clots may happen because of a major physical illness, or be caused by a person being immobile. In some instances, genetic or inherited characteristics may also increase a person’s chances of forming blood clots. In a small percentage of patients, blood clots can break away from the vein walls. When this happens, they travel through the blood’s circulatory system until they reach the lungs, where the clots become trapped. This is called a pulmonary embolism and it affects the oxygen exchange in a person’s body, making it difficult for the lungs to function properly.

The heart’s right ventricle is not well suited to excessive mechanical demands, being adapted to pump blood through the normally low-resistance, high-capacity lung circulatory path. Symptoms of pulmonary embolism can include shortness of breath, chest pain, fatigue, and dizziness.

Pulmonary embolism is the second most common cause of cardiac death in North America after coronary artery disease. However, in the majority of individuals, if a patient withstands the initial pulmonary embolus, the blood clot will dissolve and normal circulation will return.

Pulmonary Thromboendarterectomy (Surgery for Chronic Pulmonary Embolism)

In a small number of patients (0.5-2.5%), for unknown reasons a blood clot does not dissolve. This means the blood pressure remains elevated in the right side of the circulation, causing a persistent strain on the right side of the heart (right ventricle). This is called a chronic pulmonary embolism (or “chronic thromboembolic pulmonary hypertension”).

Individuals with this disorder experience symptoms ranging from shortness of breath while moving around or exercising, to chest pain, fainting spells, and severe leg and abdominal swelling. The best treatment for this problem is a surgical procedure called a pulmonary thromboendarterectomy. The procedure involves open-heart surgery and uses a heart/lung machine to stop the patient’s circulation while the surgeon works to open the arteries and remove the chronic blood clot.

Cardiomyopathy is a primary disease of the heart muscle as opposed to coronary heart disease which is a disease of the coronary blood vessels. Cardiomyopathy is due to many causes that are classified as primary and secondary.

Primary cardiomyopathy refers to a disease that is inherent in the muscle such as the inherited cardiomyopathy.

Secondary cardiomyopathy refers to a defect in the heart muscle that is secondary to a cause outside of the muscle such as hyperthyroidism. The abnormality in cardiomyopathy is decreased global function of the heart to pump out blood appropriately to the rest of the body. The function of the heart is to contract and squeeze out the blood followed by relaxation to allow the heart to refill with blood, which in medical terms are referred to as Systole (contraction) and Diastole (relaxation). In cardiomyopathies, one or both of these is globally affected throughout the chamber.

Dilated Cardiomyopathy

The chamber or chambers of the heart are enlarged, with the walls themselves being thin or normal. This leads to impaired pumping of the blood.

Hypertrophic Cardiomyopathy

The heart is enlarged only minimally, but the walls are much thicker with the chambers being normal or decreased in size. This heart is usually hyperactive but has great difficulty relaxing.

Restrictive Cardiomyopathy

This is a very rare form or cardiomyopathy due to rigid walls (e.g., amyloid). Most restricted cardiomyopathies are due to an infiltration such as amyloid or cancer.

Familial (Inherited) or Sporadic Cardiomyopathy

Familial cardiomyopathy refers to an inherited cardiomyopathy due to a genetic defect transmitted by one or more of the parents.

Sporadic cardiomyopathy is a genetic disease in which the defect arises de novo from some insult to that person’s genes (mutation). That person will now pass on the defective gene to their offspring and from that time on, it becomes a familial disease.

What’s a Normal Reaction to a Heart Event?

Feeling anxious about having a heart attack or even worrying about suddenly dying from heart problems is very common after a heart attack or heart surgery or sometimes even after a procedure such as an angioplasty. Some people may question whether they should return to work or change other aspects of their life in order to decrease stress. Most people, but not everybody, regain confidence about their ability to resume daily activities over the 3 or 4 weeks after a heart event. However, persistent symptoms of depression or anxiety after a heart attack or surgery happen to 1 in 5 persons.  Speaking with your family doctor or cardiologist about these symptoms is a good first step.

What is Meant By “Depression”?

Although many people have sad or blue feelings in the days following a heart attack or heart surgery, these usually disappear within a week or two as more confidence comes about the future. However, some patients can develop a “clinical depression” or “major depression” similar to other medical illnesses which require diagnosis and treatment.

Symptoms of major depression include:

• Feeling down, depressed, or hopeless most days of the week for at least two weeks in a row
• Loss of interest or pleasure in doing things that were enjoyable before
• Poor appetite or over-eating
• Trouble falling asleep or sleeping too much
• Feeling tired all the time or having no energy
• Feeling bad about yourself such as thinking you are a burden to others
• Being fidgety and unable to sit still, or the opposite – moving and speaking slower than normal
• Having thoughts of wanting to die or wanting to end your life

Major depression can occur in the weeks or months before a heart attack, or happen right after a heart attack or heart surgery. People with a history of depression are at greater risk of developing another episode after a heart attack or heart surgery. It is important to seek help, because major depression rarely disappears without treatment and there are several effective treatments available. Also some medical conditions, like thyroid problems, can produce symptoms similar to those of depression, and your doctor may need to test for these conditions. Finally, recent research has shown that having major depression may increase the risk of later developing heart disease. In people who already have heart disease, major depression has also been shown to increase the risk of having further heart attacks or even dying from heart disease.

What is Meant By “Anxiety”?

Anxiety symptoms happen in most people around the time of a heart attack or heart surgery but usually decrease and disappear in the next week or two. However, in some people, anxiety symptoms can persist all day long and are associated with overwhelming worry about their heart condition. Some people develop severe anxiety symptoms as part of a major depression. Anxiety symptoms can also come as sudden “panic attacks” which last minutes or even longer, and cause a person to think they are having a heart attack or dying.

Symptoms of anxiety can include:

• A feeling of shakiness inside
• Hand tremors
• Rapid breathing or feeling short of breath
• Sweating
• Muscular tension
• Being fidgety or having to pace
• Feeling faint
• Numbness or tingling in the fingers or around the mouth

What Can Be Done About Depression and Anxiety?

There are effective treatments for depression and anxiety disorders. Specialized types of psychotherapy have been shown to be effective for treatment of depression or anxiety in patients with heart disease. Cognitive therapy helps a depressed person identify negative thoughts about themselves, their world and the future, and correct these thinking errors. Interpersonal therapy helps identify and correct problems in relationships with other people, including difficulties with grief, conflict, changing roles, or lack of supportive relationships. Medication to treat anxiety can include use of a benzodiazepine medication for a few days or weeks. Antidepressant medications can be used for longer periods of time to treat both anxiety and depression. Certain antidepressant medications are shown to be safe in patients with heart disease, but interactions with other heart drugs must be kept in mind. Discussions with your family doctor or cardiologist can help you decide on what types of treatment for depression or anxiety would be best for you. In some cases, your doctor may recommend help from a psychologist or psychiatrist to help you through this difficult time.

A Final Note

It is important to realize that depression and anxiety are common in patients with heart disease and can happen to anybody. These symptoms do not indicate a weakness of character or a problem with personality, and treatment is effective. The most important step to recovery from depression or anxiety is to ask for help.