Cardiology
Overview
Cardiology is a medical specialty dealing with disorders of the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

 (specifically the human heart
Human heart
The human heart is a muscular organ that provides a continuous blood circulation through the cardiac cycle and is one of the most vital organs in the human body...

). The field includes diagnosis and treatment of congenital heart defect
Congenital heart defect
A congenital heart defect is a defect in the structure of the heart and great vessels which is present at birth. Many types of heart defects exist, most of which either obstruct blood flow in the heart or vessels near it, or cause blood to flow through the heart in an abnormal pattern. Other...

s, coronary artery disease, heart failure, valvular heart disease
Valvular heart disease
Valvular heart disease is any disease process involving one or more of the valves of the heart . Valve problems may be congenital or acquired...

 and electrophysiology
Electrophysiology
Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electric current on a wide variety of scales from single ion channel proteins to whole organs like the heart...

. Physicians who specialize in this field of medicine are called cardiologists.

Cardiologists should not be confused with cardiac surgeon
Cardiac surgeon
A cardiac surgeon is a surgeon who performs cardiac surgery—operative procedures on the heart and great vessels.-Training:A cardiac surgery residency typically comprises anywhere from six to nine years of training to become a fully qualified surgeon...

s, cardiothoracic and cardiovascular, who are surgeons who perform cardiac surgery via sternotomy — open operative procedures on the heart and great vessels.
As the center focus of cardiology, the heart has numerous anatomical features (e.g., atria
Atrium
Atrium may refer to:*Atrium , a large open space within a building usually with a glass roof*Atrium , microscopic air sacs in lungs*Atrium , an anatomical structure of the heart* Atrium of the ventricular system of the brain...

, ventricle
Ventricle
Ventricle may refer to:* Ventricle , the pumping chambers of the heart* Ventricular system in the brain* Ventricle of the larynx, a structure in the larynx* Stomach of the gastrointestinal tract...

s, heart valve
Heart valve
A heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...

s) and numerous physiological features (e.g., systole
Systole (medicine)
Systole is the contraction of the heart. Used alone, it usually means the contraction of the left ventricle.In all mammals, the heart has 4 chambers. The left and right ventricles pump together. The atria and ventricles pump in sequence...

, heart sounds
Heart sounds
Heart sounds, or heartbeats, are the noises generated by the beating heart and the resultant flow of blood through it...

, afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...

) that are of concern.
Disorders of the heart lead to heart disease
Heart disease
Heart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...

 and cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

 and they lead to a significant number of deaths: cardiovascular disease
Cardiovascular disease
Heart disease or cardiovascular disease are the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the cardiovascular system , it is usually used to refer to those related to atherosclerosis...

 is the leading cause of death
Cause of Death
Cause of Death is a 1990 album by American death metal band Obituary. Cause of Death is considered a classic album in the history of death metal. The artwork was done by artist Michael Whelan...

 and caused 29.34% of all deaths in 2002.

The primary responsibility of the heart is to pump blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 around the body.
It pumps blood from the body — called the systemic circulation
Systemic circulation
Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...

 — through the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

s — called the pulmonary circulation
Pulmonary circulation
Pulmonary circulation is the half portion of the cardiovascular system which carries Oxygen-depleted Blood away from the heart, to the Lungs, and returns oxygenated blood back to the heart. Encyclopedic description and discovery of the pulmonary circulation is widely attributed to Doctor Ibn...

 — and then back out to the body.
This means that the heart is connected and affects the entirety of the body.
While plenty is known about the healthy heart, the bulk of the study in cardiology is in the disorders of the heart and restoration, where possible, of function.

The heart is a muscle that squeezes blood and functions like a pump.
Each part of the heart is susceptible to failure or dysfunction and the heart could be divided into the mechanical and the electrical.

The electrical part of the heart is centered on the periodic contraction (squeezing) of the muscle cells that is caused by the cardiac pacemaker
Cardiac pacemaker
right|thumb|350px|Image showing the cardiac pacemaker which is the SA nodeThe contraction of heart muscle in all animals with hearts is initiated by chemical impulses. The rate at which these impulses fire controls the heart rate...

 located in the sinoatrial node
Sinoatrial node
The sinoatrial node is the impulse-generating tissue located in the right atrium of the heart, and thus the generator of normal sinus rhythm. It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava...

.
The study of the electrical aspects is a subfield of electrophysiology
Electrophysiology
Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electric current on a wide variety of scales from single ion channel proteins to whole organs like the heart...

 called cardiac electrophysiology
Cardiac electrophysiology
Cardiac electrophysiology is the science of elucidating, diagnosing, and treating the electrical activities of the heart. The term is usually used to describe studies of such phenomena by invasive catheter recording of spontaneous activity as well as of cardiac responses to programmed electrical...

 and is epitomized with the electrocardiogram
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...

 (ECG/EKG).
The action potential
Action potential
In physiology, an action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called excitable cells, which include neurons, muscle cells, and...

s generated in the pacemaker propagate throughout the heart in a specific pattern and is the system that carries this potential is called the electrical conduction system
Electrical conduction system of the heart
The normal intrinsic electrical conduction of the heart allows electrical propagation to be transmitted from the Sinoatrial Node through both atria and forward to the Atrioventricular Node. Normal/baseline physiology allows further propagation from the AV node to the ventricle or Purkinje Fibers...

.
Dysfunction of the electrical system manifests in many ways and includes Wolff–Parkinson–White syndrome, ventricular fibrillation
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...

, and heart block
Heart block
A heart block can be a blockage at any level of the electrical conduction system of the heart .* Blocks that occur within the sinoatrial node are described as SA nodal blocks....

.

The mechanical part of the heart is centered on the fluidic movement
Fluid mechanics
Fluid mechanics is the study of fluids and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion...

 of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 and the functionality of the heart as a pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

.
The mechanical part is ultimately the purpose of the heart and many of the disorders of the heart disrupt the ability to move blood.
Failure to move sufficient blood can result in failure in other organs and may result in death if severe.
Heart failure is one condition in which the mechanical properties of the heart have failed or are failing, which means insufficient blood is being circulated.

There exists other disorders of the heart that disrupt both the electrical and the mechanical properties of the heart.
A more poignant disorder is that of a myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...

 (MI) or heart attack.
An MI causes cellular death of the heart which reduces both the electrical and mechanical capabilities of the heart and can lead to death if severe.
Cardiology is concerned with the normal functionality of the heart and the deviation from a healthy heart.
Many disorders involve the heart itself but some are outside of the heart.
 
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