Anatomy

Afterload (Cardiac Output)

The afterload is a measure of the pressure in the blood vessels that the left ventricle must pump against.

Anterior

This refers to something in the front or in front of.

Aorta

The aorta is the main artery of the body, arising from the base of the left ventricle of the heart. It supplies oxygenated blood to all arteries except the pulmonary artery (which carries blood to the lungs to be oxygenated). The aorta curves after cardiac takeoff and down the chest into the abdomen, where it divides into two smaller arteries. It is a large vessel, about one-inch in diameter, with thick, elastic walls to withstand the changes in pressure as the heart beats.

Arterioles

These are blood carrying, minute arteries that have more muscle, allowing them to respond better to a need to change diameter. These are continuous with the capillary network.

Artery

Arteries are relatively thick-walled, muscular, pulsating blood vessels conveying blood in a direction away from the heart. With the exception of the pulmonary and umbilical arteries, the arteries carry red or oxygen-rich blood.

Atrioventricular (AV) Valves

These are valves in the heart muscle that separate the atria from the ventricles. The Tricuspid valve is on the right side of the heart and the Mitral (or Bicuspid) valve is on the left side of the heart.

Blood Pressure

Blood pressure is the force of blood against the walls of the arteries. This force is created by the heart as it pumps blood to all parts of the body. In some people, blood pressure is nearly always higher than it should be. Doctors still don't know what causes most high blood pressure, but they can help you control it.

High blood pressure adds to the workload of the heart and arteries. The heart must pump with more force, and the arteries must carry blood that is moving under greater pressure. If high blood pressure continues for a long time, the heart and the arteries may not function as well as they should and other body organs may also be affected. There is increased risk of stroke, heart failure, kidney failure and heart attack.

Most people with high blood pressure have no symptoms at all. There are no specific warning signs. The only way to find out if you have high blood pressure is to have your doctor check it or visit a local blood pressure screening program.

If you have high blood pressure, you can do a great deal to reduce it. First, work with your doctor to determine the best treatment for you. It may include a low-fat diet, a low-salt diet, and changes in your living habits such as quitting smoking, losing weight, and getting more exercise. Reducing your alcohol intake may be recommended. If you are on a weight reduction diet, remember alcohol is high in

calories.

In addition, many medications can be used to reduce and control high blood pressure. Your doctor will decide whether you need drug treatment in addition to dietary and lifestyle changes.

Blood Pressure

This is the force of blood against the walls of the arteries. This pressure is created by the heart as it pumps blood to all parts of the body. In some people, blood pressure is nearly always higher than it should be. Doctors still don't know what causes most high blood pressure, but they can help you control it.

High blood pressure adds to the workload of the heart and arteries. The heart must pump with more force, and the arteries must carry blood that is moving under greater pressure. If high blood pressure continues for a long time, the heart and the arteries may not function as well as they should and other body organs may also be affected. There is increased risk of stroke, heart failure, kidney failure and heart attack.

Cardiac Cycle

The cardiac cycle is the sequence of events which occur during the pumping and relaxation of the heart that cause move blood forward.

Systole

· Isovolumetric contraction – The heart muscle contracts but the volume of blood in the ventricles does not change.

Rapid ejection phase – The pulmonic and aortic valves open because of increasing pressure and the blood leaves the chambers with high force.

· Reduced ejection phase – The remainder of the blood to be ejected leaves the ventricles as the pressure decreases and the muscle prepares to relax.

Diastole

· Isovolumetric relaxation – The heart muscle is relaxing. Pressure in the ventricle is decreasing and no blood is moving into it as yet.

· Rapid ventricular filling – Pressure in the ventricles is lower than in the atria. The tricuspid and Mitral valves open and blood rapidly flows into the ventricles.

· End Diastole – During this “atrial kick”, the atria contract forcing an additional 15-20% of the blood volume into the ventricles before the valves close. Following this, the systolic phase is ready to being again.

Cardiac Output

This is the amount of blood pumped with each beat of the heart. Blood pressure is one measure of this output.

Cardiac Physiology Defined

A basic physical relationship that can be applied to the flow of blood throughout the body is:

Pressure = Flow X Resistance to that flow

Pressure in a vessel “pipe” is changed by changing the flow {amount of blood moving through it} or the resistance {the size of the diameter of the vessel}.

Blood Pressure = Cardiac Output X Vascular Resistance

Carotid Arteries

These major arteries, located on either side of the neck, convey blood from the heart to the brain.

CIA

The CIA is the common iliac artery.

Collateral Circulation

The body develops small vessels around a larger vessel that has been blocked. If these small vessels are encountered, this usually indicates that vascular disease has been present for some time.

Coronary Vasculature

Coronary Arteries which branch off the base of the aorta just past the aortic valve:

Diagonal

This is the major branch of the LAD.

Left Anterior Descending Coronary Artery (LAD)

The LAD artery supplies blood to the anterior left ventricle, the interventricular septum.

Left Circumflex (LCX)

The LCX artery supplies blood to the lateral and diaphragmatic surface of the left ventricle.

Left Main Coronary Artery (LMCA)

The LMCA is a very short large diameter artery branching into the LAD and LCX.

Obtuse Marginal Branch (OMB)

This is the major arterial branch of the LCX supplying the lateral left ventricle.

Posterior Descending Artery (PDA)

The PDA branches off of the RCA and supplies most of the right ventricle and the back of the left ventricle.

Right Coronary Artery (RCA)

This artery supplies the right atrium and ventricle. It has several primary branches.

Endocardium (Heart Muscle Layer)

The endocardium is composed of thin layers of endothelium and connective tissue within the heart that line the insides of the chambers and cover the valves and chordea tendonae and papillary muscles.

Diagonal

The diagonal is the major branch of the left anterior descending artery of the heart.

Ejection fraction and volumes

This is an evaluation of the amount of blood ejected during each contraction of the left ventricle of the heart, as well an as assessment of the volume of blood flowing through the heart. This evaluation is used to assess heart function.

Epicardium (Heart Muscle Layer)

The epicardium is the outer layer of the heart muscle itself. It covers not only the outer surface of the heart but the great vessels as well.

Heart, Chambers

Right Atrium – This receives deoxygenated blood from the body.

Right Ventricle – This pumps blood through the lungs.

Left Atrium – This receives oxygenated blood from the lungs.

Left Ventricle – This pumps oxygen enriched blood through the body.

Heart Rate (Cardiac Output)

Heart rate is measured as heart beats per minute.

Heart, Valves – The following valves are responsible for the directed flow of blood through the heart:

Atrioventricular (AV) - These valves separate the atria from the ventricles.

Tricuspid Valve – The tricuspid valve is on the right side of the heart.

Mitral Valve The mitral valve (also called the bicuspid) is on the left side of the heart.

Semilunar Valves:

Pulmonic – The pulmonic valve is located at the right ventricle leading to the lungs.

Aortic – The aortic valve permits blood flow from the left ventricle to the body.

Inferior Vena Cava

This is one of the Great Vessels that empties blood from the lower portion of the body into the right atrium.

Lateral

This refers to something at the side of or beside.

Left Anterior Descending Coronary Artery (LAD)

The LAD supplies the anterior left ventricle, the interventricular septum of the heart with oxygen-rich blood.

Left Atrium (Heart Chamber)

The left atrium receives oxygenated blood from the lungs.

Left Circumflex (LCX)

The LCX supplies the lateral and diaphragmatic surface of the left ventricle of the heart with oxygenated blood.

Left Main Coronary Artery (LMCA)

The LMCA is a very short large diameter artery branching into the left anterior descending (LAD) and left circumflex (LCX) arteries of the heart.

Left Ventricle (Heart Chamber)

The left ventrical pumps oxygen enriched blood through the body.

Medial

This refers to something in the middle or closest to the middle.

Myocardial Contractility (Cardiac Output)

This is the characteristic of the myocardium (the main pumping muscle of the heart) with regard to contracting or squeezing.

Myocardial (Heart) Muscle, Layers

Pericardial Sac

The pericardial sac is a strong elastic, fibrous connective tissue layer. It contains a small amount of fluid that allows for the heart to move easily inside. It provides protection against infection and trauma.

Epicardium

The epicardium is the outer layer of the heart muscle itself. It covers not only the outer surface of the heart but the great vessels as well.

Myocardium

The myocardium is the muscular middle layer within the heart. It is responsible for the blood pumping function of the heart.

Endocardium

The endocardium is comprised of thin layers of endothelium and connective tissue that line the inside of the heart chambers and cover the valves, chordea tendonae and papillary muscles inside the heart.

Obtuse Marginal Branch (OMB)

The OMB is the major branch of the left circumflex artery (LCX) supplying the lateral left ventricle of the heart with oxygenated blood.

Pericardial Sac (Heart Muscle Layer)

The pericardial sac is a strong elastic, fibrous connective tissue layer. It contains a small amount of fluid that allows for the heart to move easily inside. It provides protection against infection and trauma.

Posterior

This refers to something behind or in back of.

Posterior Descending Artery (PDA)

The PDA branches off from the right coronary Artery (RCA) and supplies most of the right ventricle and back of the left ventricle of the heart with oxygenated blood.

Pressure Gradient

The pressure gradient is the difference in blood pressure between two areas of the body. Anything in excess of 10 mm of mercury (10 mm Hg) is considered significant.

Pulmonary Artery

The pulmonary artery delivers blood from the heart to the lungs for oxygenation.

Pulmonary Veins

Two pulmonary veins from each lung return oxygenated blood to the left atrium.

Right Atrium (Heart Chamber)

The right atrium receives deoxygenated blood from the body.

Right Coronary Artery (RCA)

The RCA supplies the right atrium and ventricle with oxygenated blood. It has several primary branches.

Right Ventricle (Heart Chamber)

The right ventricle pumps blood through the lungs.

Semilunar Valves:

Pulmonic

The pulmonic valve is located at the right ventricle leading to the lungs.

Aortic

The aortic valve permits blood flow from the left ventricle to the body.

SFA

The SFA is the superficial femoral artery.

SMA

The SMA is the superior mesenteric artery.

Superior Vena Cava

The superior vena cava is one of the Great Vessels which empties blood into the right atrium from the upper portion of the body.

TPT

The TPT is the tibial peronial trunk.

Vessels, Great

Vena Cava:

Superior Vena Cava – This vessel empties blood into the right atrium from the upper portion of the body.

Inferior Vena Cava – This vessel empties blood to the right atrium from the lower portion of the body.

Vascular Physiology

Blood Pressure – This is the force per unit area exerted by the blood against the walls of a vessel.

Systolic – This is the maximum pressure achieved in response to ventricular contraction. It is the top number in a blood pressure reading.

Diastolic – This is the residual pressure exerted by the blood remaining in the vessel during ventricular relaxation. It is the bottom number of a blood pressure reading.

Ventricular Fibrillation

Ventricular fibrillation is an exceedingly rapid series of contractions (similar to twitching) of small parts of the ventricular muscle of the heart.