cardiology

Cardiology (from Greek καρδίᾱ, kardiā, "heart"; and -λογία, -logia) is a medical specialty dealing with disorders of the heart (specifically the human heart). The field includes diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart disease and electrophysiology. Physicians who specialize in this field of medicine are called cardiologists.

Cardiologists should not be confused with cardiac surgeons, cardiothoracic and cardiovascular, who are surgeons who perform cardiac surgery via sternotomy — open operative procedures on the heart and great vessels.

The heart

Blood flow diagram of the human heart. Blue components indicate de-oxygenated blood pathways and red components indicate oxygenated pathways.

As the center focus of cardiology, the heart has numerous anatomical features (e.g., atria, ventricles, heart valves) and numerous physiological features (e.g., systole, heart sounds, afterload) that are of concern. Disorders of the heart lead to heart disease and cardiovascular disease and they lead to a significant number of deaths: cardiovascular disease is the leading cause of death and caused 29.34% of all deaths in 2002.[citation needed]

The primary responsibility of the heart is to pump blood around the body. It pumps blood from the body — called the systemic circulation — through the lungs — called the pulmonary circulation — 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 located in the sinoatrial node. The study of the electrical aspects is a subfield of electrophysiology called cardiac electrophysiology and is epitomized with the electrocardiogram (ECG/EKG). The action potentials 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. Dysfunction of the electrical system manifests in many ways and includes Wolff–Parkinson–White syndrome, ventricular fibrillation, and heart block.

The mechanical part of the heart is centered on the fluidic movement of blood and the functionality of the heart as a pump. 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 (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.

Disorders

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. It is possible to keep your heart healthy by following some simple routines.

Disorders of the coronary circulation

Coronary arteries labeled in red text and other landmarks in blue text.

Contrary to a basic understanding of the cardiovascular system, the heart cannot receive enough oxygen and nutrients from the blood it pumps and it must be supply itself with blood as if it were any other organ in the body. This circulation of blood is called the coronary circulation. The coronary circulation consists of coronary arteries and coronary veins.

Disorders of the coronary circulation can have devastating effects to the heart since damage to the heart can reduce coronary circulation which causes further damage.

Acute coronary syndrome (ACS) 

Acute coronary syndrome is a broad term encompassing many acute myocardial infarction symptoms.

Angina pectoris

Angina pectoris literally means "breast pain" that refers to chest pain caused by ischemia of the heart.

Atherosclerosis

Atherosclerosis is the condition in which an artery wall thickens as the result of a build-up of fatty materials (e.g., cholesterol). Atherosclerosis of a coronary artery leads to coronary heart disease.

Coronary heart disease

Coronary heart disease is a general term for any reduction in coronary circulation. One such condition is atherosclerosis.

Myocardial infarction (aka heart attack) 

A myocardial infarction is the death of a part of the heart which is typically caused by a blockage of the coronary circulation or coronary heart disease.

Restenosis

Recurrence of stenosis which would refer to a coronary artery in the context of the coronary circulation.

Cardiac arrest

A rhythm strip showing a couple beats of normal sinus followed by an atrial beat and asystole ("flatline").

Cardiac arrest refers to the cessation(to cease)of normal systemic circulation due to failure in proper contraction of the heart. There are several conditions that can cause cardiac arrest.

Asystole ("flatline") 

Asystole refers to the absence of electrical activity of the heart and is sometimes referred to as a "flatline" because the electrocardiogram shows a solid line due to the absence of electrical activity.

Pulseless electrical activity (PEA) 

Pulseless electrical activity is when the electrocardiogram shows a rhythm that should produce a pulse but it does not. PEA is commonly caused by the 6 H's and 6 T's (see PEA article).

Pulseless ventricular tachycardia

Pulseless ventricular tachycardia (VT) Is one classification of VT such that no pulse is felt because of an ineffective cardiac output which causes cardiac arrest.

Sudden cardiac death

Sudden cardiac death is a concept of natural death rather than a specific medical condition. There are several causes of sudden cardiac death and it is distinct from cardiac arrest.

Ventricular fibrillation

Ventricular fibrillation is fibrillation of the ventricles of the heart. Rhythmic contraction is necessary for efficient movement of blood and fibrillation disrupts this rhythm sufficiently to cause cardiac arrest.

Treatment of cardiac arrest includes cardiopulmonary resuscitation (CPR) and defibrillation depending on the exact cause of cardiac arrest.

Disorders of the myocardium (muscle of the heart)

The diagram shows a healthy heart (left) and one suffering from right ventricular hypertrophy (right).

A man with congestive heart failure and marked jugular venous distension. External jugular vein marked by an arrow.

Cardiomyopathy

Cardiomyopathy is a deterioration of the myocardium.

Ischemic cardiomyopathy 

Cardiomyopathy causing ischemia of the heart due to coronary artery disease.

Nonischemic cardiomyopathy 

Cardiomyopathy not caused by ischemia of the heart.

Amyloid cardiomyopathy

Cardiomyopathy caused by amyloidosis.

Hypertrophic cardiomyopathy (HCM) 

Cardiomyopathy caused by hypertrophy of the heart.

Hypertrophic obstructive cardiomyopathy (HOCM) (Idiopathic hypertrophic subaortic stenosis (IHSS)) 

Dilated cardiomyopathy

Cardiomyopathy caused by dilation of the heart.

Alcoholic cardiomyopathy

A type of dilated cardiomyopathy caused by chronic abuse of alcohol.

Tachycardia induced cardiomyopathy

A type of dilated cardiomyopathy caused by chronic tachycardia.

Takotsubo cardiomyopathy (Transient apical ballooning, stress-induced cardiomyopathy) 

A type of dilated cardiomyopathy caused by a sudden temporary weakening of the myocardium.

Arrhythmogenic right ventricular dysplasia (Arrhythmogenic right ventricular cardiomyopathy) 

Cardiomyopathy caused by a genetic mutation of the desmosomes that connect myocytes.

Restrictive cardiomyopathy

Cardiomyopathy caused by excessive rigidity of the heart.

Heart failure

Failure of the heart to produce sufficient blood flow to meet metabolic demands of the body.

Cor pulmonale

Untreated cor pulmonale can cause right heart failure from chronic pulmonary hypertrophy.

Ventricular hypertrophy

Hypertrophy of the ventricle.

Left ventricular hypertrophy

Hypertrophy of the left ventricle.

Right ventricular hypertrophy

Hypertrophy of the right ventricle.

Primary tumors of the heart

Tumors that arise initially in the heart and not from elsewhere in the body.

Myxoma

Most common tumor of the heart.

Myocardial rupture

A gross structural failure of the heart. Commonly a result of myocardial infarction.

Disorders of the pericardium (outer lining of the heart)

Posterior wall of the pericardial sac.

The pericardium is a double-walled sac — fibrous pericardium and serous pericardium — that contains the heart.

Constrictive pericarditis

Pericarditis that constricts the expansion of the heart and inhibits heart function.

Pericardial effusion

An abnormal accumulation of fluid in the pericardium that can lead to tamponade.

Pericardial tamponade

Accumulation of fluid in the pericardium that inhibits heart function.

Pericarditis

Inflammation of the pericardium.

Disorders of the heart valves

3D reconstruction of the heart as viewed from the apex towards the valves, image flipped 180° relative to illustration above. Pulmonary valve not visible, leaflets of the tricuspid and aortic valves only partly visible. To the left two images in 2D from the same dataset, showing tricuspid and mitral valves (above) and aortal and mitral valve (below).

The heart contains four valves that direct the flow of blood in a single direction. Failure to prevent reverse-flow is called regurgitation, or insufficiency. Narrowing of the valves obstructs flow and is called stenosis.

Aortic valve

Disorders and treatments of the aortic valve that separates the left ventricle and aorta.

Aortic regurgitation / aortic insufficiency 

Deficiency of the aortic valve that permits regurgitation from the aorta into the left ventricle.

Aortic stenosis

Narrowing of the aortic valve opening that reduces blood flow through the valve.

Aortic valve replacement

Replacement of the aortic valve due to aortic regurgitation, aortic stenosis, or other reasons.

Aortic valve repair

Repair, instead of replacement, of the aortic valve.

Aortic valvuloplasty

Repair of the valve by using a balloon catheter to force it open.

Mitral valve

Disorders and treatments of the mitral valve that separates the left atrium and left ventricle.

Mitral valve prolapse

Prolapse of the mitral valve into the left atrium during ventricular systole.

Mitral regurgitation / mitral insufficiency 

Deficiency of the mitral valve that permits regurgitation from the left ventricle into the left atrium.

Mitral stenosis

Narrowing of the mitral valve opening that reduces blood flow through the valve.

Mitral valve replacement

Replacement of the mitral valve due to mitral regurgitation, mitral stenosis, or other reasons.

Mitral valve repair

Repair, instead of replacement, of the mitral valve.

Mitral valvuloplasty

Repair of the valve by using a balloon catheter to force it open.

Pulmonary valve

Disorders of the pulmonary valve that separates the right ventricle and pulmonary artery.

Pulmonary regurgitation / pulmonary insufficiency 

Deficiency of the pulmonary valve that permits regurgitation from the pulmonary artery into the right ventricle.

Pulmonic stenosis

Narrowing of the pulmonary valve opening that reduces blood flow through the valve.

Tricuspid valve

Disorders of the tricuspid valve that separates the right atrium and right ventricle.

Tricuspid regurgitation / tricuspid insufficiency 

Deficiency of the tricuspid valve that permits regurgitation from the right ventricle into the right atrium.

Congenital heart defect

Atrial septal defect with left-to-right shunt.

Congenital heart defects are defects in the structure of the heart which are present at birth.

Atrial septal defect

Defect in the interatrial septum that permits blood flow between atria, including a patent foramen ovale (PFO).

Bicuspid aortic valve

Formation of two valve leaflets in the aortic valve instead of three leaflets.

Hypoplastic left heart syndrome

Defect in the development of the left heart such that it is hyperplastic (under developed).

Patent ductus arteriosus (PDA) 

Failure of the ductus arteriosus to close on birth.

Patent foramen ovale (PFO) 

An atrial septal defect in that the foramen ovale fails to close at birth.

Persistent truncus arteriosus

Defect in that the truncus arteriosus fails to divide.

Tetralogy of Fallot

Set of four anatomical abnormalities: pulmonary stenosis, overriding aorta, ventricular septal defect, and right ventricular hypertrophy.

Transposition of the great vessels (TGV) 

Abnormal spatial arrangement of the great vessels (superior vena cava, inferior vena cava, pulmonary arteries, pulmonary veins, and aorta).

Ventricular septal defect

Defect in the ventricular septum that permits blood flow between ventricles.

Diseases of blood vessels (vascular diseases)

The progression of atherosclerosis (size exaggerated).

Atherosclerosis

Thickening of an arterial wall due to increased cholesterol and macrophages.

Aneurysm

Balloon-like bulging of the artery.

Aorta

Diseases of the aorta

Coarctation of the aorta

Narrowing of the aorta at the ductus arteriosus/ligamentum arteriosum.

Aortic dissection

Dissection along the length of the aorta between the layers of the aortic wall and filled with blood.

Aortic aneurysm

Aneurysm of the aorta.

Carotid artery

Diseases of the carotid arteries

Carotid artery stenosis / carotid artery disease 

Narrowing of the carotid artery, typically due to atherosclerosis.

Carotid artery dissection

Dissection along the length of the carotid artery between the layers of the carotid wall and filled with blood.

Deep vein thrombosis (DVT) 

Formation of a thrombus in a deep vein, commonly in the legs.

Traveller's thrombosis / economy class syndrome 

A DVT due to being sedentary during air travel.

Varicose veins

Veins that have become enlarged and tortuous with failed valves, commonly in the legs.

Vasculitis

Inflammation of blood vessels.

Procedures to counter coronary artery disease

An example of a drug-eluting stent. This is the TAXUS Express² Paclitaxel-Eluting Coronary Stent System, which releases paclitaxel.

Coronary artery bypass surgery (CABG) 

Grafting an artery or vein from elsewhere (typically the leg) to bypass a stenotic coronary artery.

Enhanced external counterpulsation (EECP) 

Pneumatically assisting the heart move blood through cuffs on the legs.

Percutaneous coronary intervention (PCI) 

Procedures to treat stenotic coronary arteries by accessing through a blood vessel.

Percutaneous Transluminal Coronary Angioplasty (PTCA) 

Enlarging the lumen of a coronary artery by forcibly expanding it with a balloon.

Atherectomy

Enlarging the lumen of a coronary artery by removal of atherosclerotic plaque.

Stenting 

Enlarging the lumen of a coronary artery by forcibly expanding it with a metal wire tube.

Devices used in cardiology

A stethoscope.

Stethoscope

Acoustic device for hearing internal sounds including heart sounds.

Devices used to maintain normal electrical rhythm

Pacemaker

An implanted electrical device that replaces the heart's natural pacemaker.

Defibrillator

Electrical devices to alter the heart's rhythm with electrical energy.

Automated external defibrillator (AED) 

An external defibrillator that is commonly found outside of health care settings. Often designed for anyone to use.

Implantable cardioverter-defibrillator (ICD) 

An implanted device to prevent life-threatening conditions (e.g., ventricular tachycardia, ventricular fibrillation).

Devices used to maintain blood pressure

Artificial heart

An internal pump that wholly replaces the pumping action of the heart.

Cardiopulmonary bypass (CPB) / heart-lung machine 

External pump to take over the function of both the heart and lungs.

Intra-aortic balloon pump (IABP) 

A balloon placed in the thoracic aorta to supplement cardiac output from the heart.

Ventricular assist device

Internal pump to supplement or replace the pumping action of a ventricle.

Diagnostic tests and procedures

Cardiologists use diagrams like this: a heart with an ECG indicator

Various cardiology diagnostic tests and procedures.

Blood tests

Echocardiography ("echo") 

Ultrasonography of the heart to inspect chambers, valves, and blood flow.

Transthoracic echocardiogram (TTE) 

Echocardiogram of the heart through the thorax external to the body.

Transesophageal echocardiogram (TEE) 

Echocardiogram of the heart through a catheter placed in the esophagus.

Cardiovascular magnetic resonance imaging (CMR) 

Magnetic resonance imaging (MRI) of the heart that utilizes the ECG for gating and to look at specific mechanical functions of the heart.

Cardiac stress test

Testing of the cardiovascular system through controlled exercise or drugs.

Auscultation

Listening to sounds (e.g., heart sounds) with a stethoscope.

Electrocardiography (ECG or EKG) 

Measurement of the electrical activity of the heart, typically with 4 or 10 electrodes on the skin.

Holter monitor

Portable ECG device for continuous monitoring.

Electrophysiology study

Studying the electrical activity of the heart through the use of catheters placed in the heart via veins or arteries.

Sphygmomanometer

Blood pressure cuff used to measure arterial blood pressure.

Cardiac marker

Testing for biomarkers in the blood that may indicate various conditions.

Coronary catheterization

Catheterization of the coronary arteries.

Fractional flow reserve (FFRmyo) 

Testing of the flow through a stenosis of a coronary artery to determine the perfusion of the heart.

Intravascular ultrasound (IVUS) 

Ultrasonography of a coronary artery.

Optical coherence tomography (OCT) 

Testing through the use of optical scattering for coronary artery disease.

Cardiologists

• Robert Atkins (1930-2003), known for the Atkins diet
• Eugene Braunwald (born 1929), editor of Braunwald's Heart Disease and 1000+ publications
• Willem Einthoven (1860-1927), a physiologist who built the first practical ECG and won the 1924 Nobel prize in medicine
• Andreas Gruentzig (1939-1985), first developed balloon angioplasty
• Samuel A. Levine (1891-1966), recognized the sign known as Levine's sign
• Henry Marriott (1917-2007), ECG interpretation and Marriott's Practical Electrocardiography
• John Parkinson (1885-1976), known for Wolff–Parkinson–White syndrome
• Helen B. Taussig (1898-1986), founder of pediatric cardiology and extensively worked on blue baby syndrome
• Paul Dudley White (1886-1973), known for Wolff–Parkinson–White syndrome
• Louis Wolff (1898-1972), known for Wolff–Parkinson–White syndrome

Journals

• Acta Cardiologica
• American Journal of Cardiology
• Annals of Cardiac Anaesthesia
• Cardiology
• Cardiology in Review
• Circulation
• Circulation Research
• Clinical and Experimental Hypertension
• Clinical Cardiology
• EP – Europace
• European Heart Journal
• Heart
• Heart Rhythm
• International Journal of Cardiology
• Journal of the American College of Cardiology
• Pacing and Clinical Electrophysiology

Associations

• American College of Cardiology
• American Heart Association
• National Heart Foundation of Australia

See also

medicine portal

• Interventional cardiology
• Clinical cardiac electrophysiology
• List of cardiac pharmaceutical agents

References

External links

• U.S. National Institute of Health (NIH) : Heart and Circulation
• American College of Cardiology
• The Beginners Guide to Understanding Cardiology
• Cardiology news website