Editing Cardiology (section)

== The heart ==
[[File:Latidos.gif|thumb|Blood flow through the valves]]

{{main|Heart}}

As the center focus of cardiology, the heart has numerous anatomical features (e.g., [[atrium (heart)|atria]], [[Ventricle (heart)|ventricle]]s, [[heart valve]]s) and numerous physiological features (e.g., [[systole (medicine)|systole]], [[heart sounds]], [[afterload]]) that have been encyclopedically documented for many centuries. The heart is located in the middle of the abdomen with its tip slightly towards the left side of the abdomen.

Disorders of the heart lead to [[heart disease]] and cardiovascular disease and can lead to a significant number of deaths: cardiovascular disease is the leading [[cause of death]] in the U.S. and caused 24.95% of total deaths in 2008.<ref>{{cite journal|last1=Pagidipati|first1=Neha Jadeja|last2=Gaziano|first2=Thomas A.|title=Estimating Deaths From Cardiovascular Disease: A Review of Global Methodologies of Mortality Measurement|journal=Circulation|date= 2013|volume=127|issue=6|pages=749–756| doi=10.1161/CIRCULATIONAHA.112.128413|pmid=23401116|language=en|issn=0009-7322|pmc=3712514}}</ref>

The primary responsibility of the heart is to pump blood throughout the body.
It pumps blood from the body — called the [[systemic circulation]] — through the [[lung]]s — called the [[pulmonary circulation]] — and then back out to the body. This means that the heart is connected to and affects the entirety of the body. Simplified, the heart is a circuit of the [[Circulatory system|circulation]].<ref>{{cite web |title=How the Heart Works |url=https://www.nhlbi.nih.gov/health/heart/blood-flow |website=NHLBI |publisher=National Heart, Lung, and Blood Institute |access-date=28 February 2025}}</ref> While plenty is known about the healthy heart, the bulk of study in cardiology is in disorders of the heart and restoration, and where possible, of function.

The heart is a muscle that squeezes blood and functions like a pump. The heart's systems can be classified as either electrical or mechanical, and both of these systems are susceptible to failure or dysfunction.

The electrical system of the heart is centered on the periodic contraction (squeezing) of the [[myocardium|muscle cells]] that is caused by the [[cardiac pacemaker]] located in the [[sinoatrial node]].
The study of the electrical aspects is a sub-field of [[electrophysiology]] called [[cardiac electrophysiology]] and is epitomized with the electrocardiogram (ECG/EKG).
The [[action potential]]s generated in the pacemaker propagate throughout the heart in a specific pattern. The system that carries this potential is called the [[electrical conduction system of the heart|electrical conduction system]].
Dysfunction of the electrical system manifests in many ways and may include [[Wolff–Parkinson–White syndrome]], [[ventricular fibrillation]], and [[heart block]].<ref>{{Citation|last1=Kashou|first1=Anthony H.|title=Physiology, Sinoatrial Node|date=2021|url=http://www.ncbi.nlm.nih.gov/books/NBK459238/|work=StatPearls|place=Treasure Island (FL)|publisher=StatPearls Publishing|pmid=29083608|access-date=2021-04-22|last2=Basit|first2=Hajira|last3=Chhabra|first3=Lovely}}</ref>

The mechanical system of the heart is centered on the [[fluid mechanics|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.
[[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. Failure to move a sufficient amount of blood through the body can cause damage or failure of other organs and may result in death if severe.<ref>{{Cite book|last1=Mebazaa|first1=Alexandre|url=https://books.google.com/books?id=1YSFaSXeE3AC&q=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|title=Acute Heart Failure|last2=Gheorghiade|first2=Mihai|last3=Zannad|first3=Faiez|last4=Parrillo|first4=Joseph E.|date=2009-12-24|publisher=Springer Science & Business Media|isbn=978-1-84628-782-4|language=en}}</ref>

=== Coronary circulation ===
{{Main|Coronary circulation}}

Coronary circulation is the circulation of blood in the [[blood vessel]]s of the [[heart muscle]] (the myocardium). The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. These include the [[great cardiac vein]], the [[middle cardiac vein]], the [[small cardiac vein]] and the [[anterior cardiac veins]].

As the left and right coronary arteries run on the surface of the heart, they can be called epicardial coronary arteries. These arteries, when healthy, are capable of autoregulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. These relatively narrow vessels are commonly affected by [[atherosclerosis]] and can become blocked, causing [[Angina pectoris|angina]] or myocardial infarction (a.k.a., a heart attack). The coronary arteries that run deep within the myocardium are referred to as subendocardial.

The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium; there is very little redundant blood supply, which is why blockage of these vessels can be so critical.

=== Cardiac examination ===
{{Main|Cardiac examination}}

The cardiac examination (also called the "precordial exam"), is performed as part of a [[physical examination]], or when a patient presents with [[chest pain]] suggestive of a cardiovascular [[pathology]]. It would typically be modified depending on the [[Indication (medicine)|indication]] and integrated with other examinations especially the [[respiratory examination]].<ref>{{Cite journal |last=Maher |first=Toby M. |date=2012-11-01 |title=A Clinical Approach to Diffuse Parenchymal Lung Disease |url=https://www.sciencedirect.com/science/article/abs/pii/S088985611200104X |journal=Immunology and Allergy Clinics of North America |series=Interstitial Lung Disease and Autoimmune Lung Diseases |volume=32 |issue=4 |pages=453–472 |doi=10.1016/j.iac.2012.08.004 |issn=0889-8561}}</ref>

Like all medical examinations, the cardiac examination follows the standard structure of inspection, palpation and auscultation.<ref>According to the University of California, San Francisco, a comprehensive cardiac examination involves these three critical steps: inspection, palpation, and auscultation. This process helps in evaluating the heart's condition by first observing for visible signs, then feeling for abnormalities, and finally listening to the heart sounds.</ref><ref>Similarly, Chamberlain University outlines that the cardiac examination starts with inspection to identify any visual anomalies, followed by palpation to assess physical findings such as thrills or heaves, and concludes with auscultation to detect any abnormal heart sounds like murmurs or gallops.</ref>