Heart Function
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.
If you know you have heart disease (atrial fibrillation, mitral valve regurgitation, coronary artery disease, or other), the surgeons at Western Cardiovascular Associates are pioneers in the treatment of cardiac and cardiovascular disorders. Whether you live in Salt Lake City, Ogden, Utah Valley, or anywhere in the country, know your options - call 801-743-4750 or contact us today.
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. [Suggest including a diagram of the EKG wave.] At Western Cardiovascular Associates, we use various monitoring systems to evaluate the electrical activity of your heart. Some monitors will need to be worn at home over a set period of time, but monitoring is a non-invasive diagnostic test that allows our surgeons to determine the overall health of your heart.
The surgeons at Western Cardiovascular Associates of the Utah Valley are pioneers in the treatment of heart disease and cardiovascular disorders. Learn about their innovative, cutting-edge, therapies and how they utilize state-of-the-art technology to provide unparalleled treatment options in a compassionate and caring environment. Call 801-743-4750 or contact us today.