Editing Heart (section)

===Diagnosis===
Heart disease is diagnosed by the taking of a [[medical history]], a [[cardiac examination]], and further investigations, including [[blood test]]s, [[echocardiogram]]s, [[electrocardiograms]], and [[cardiac imaging|imaging]]. Other invasive procedures such as [[cardiac catheterisation]] can also play a role.{{sfn|Davidson's|2010|pp=527–534}}

====Examination====
{{Main|Cardiac examination|Heart sounds}}

The cardiac examination includes inspection, feeling the chest with the hands ([[palpation]]) and listening with a stethoscope ([[auscultation]]).<ref name="Davidsons2010_1">{{cite book|last1=Davidson|first1=Sir Stanley|last2=Colledge|first2=Nicki R.|last3=Walker|first3=Brian R.|last4=Ralston|first4=Stuart|title=Davidson's Principles and Practice of Medicine|date=2010|publisher=Churchill Livingstone/Elsevier|location=Edinburgh|isbn=978-0-7020-3084-0|pages=522–536|edition=21st}}</ref>{{sfn|Davidson's|2010|pp=522–536}} It involves assessment of [[medical sign|signs]] that may be visible on a person's hands (such as [[splinter haemorrhage]]s), joints and other areas. A person's pulse is taken, usually at the [[radial artery]] near the wrist, in order to assess for the rhythm and strength of the pulse. The [[blood pressure]] is taken, using either a manual or automatic [[sphygmomanometer]] or using [[Blood pressure#Invasive|a more invasive measurement]] from within the artery. Any elevation of the [[jugular vein|jugular venous pulse]] is noted. A person's [[chest]] is felt for any transmitted vibrations from the heart, and then listened to with a stethoscope.

====Heart sounds====
[[File:Apikal4D.gif|thumb|[[Echocardiography#Three-dimensional echocardiography|3D echocardiogram]] showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right).<br /> The closure of the heart valves causes the [[heart sounds]].]]
{{listen|filename=HROgg.ogg|title=Normal heart sounds|description=Normal heart sounds as heard with a [[stethoscope]]|format=[[Ogg]]}}
Typically, healthy hearts have only two audible [[heart sounds]], called S1 and S2. The [[first heart sound]] S1, is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as "lub". The [[second heart sound]], S2, is the sound of the semilunar valves closing during ventricular diastole and is described as "dub".<ref name="CNX2014"/> Each sound consists of two components, reflecting the slight difference in time as the two valves close.<ref name="TC2014">{{cite book|title=Clinical Examination|last1=Talley|first1=Nicholas J.|last2=O'Connor|first2=Simon|publisher=Churchill Livingstone|isbn=978-0-7295-4198-5|pages=76–82|year=2013}}</ref> S2 may [[split S2|split]] into two distinct sounds, either as a result of inspiration or different valvular or cardiac problems.<ref name=TC2014/> Additional heart sounds may also be present and these give rise to [[gallop rhythm]]s. A [[third heart sound]], S3 usually indicates an increase in ventricular blood volume. A [[fourth heart sound]] S4 is referred to as an atrial gallop and is produced by the sound of blood being forced into a stiff ventricle. The combined presence of S3 and S4 give a quadruple gallop.<ref name="CNX2014"/>
[[Heart murmur]]s are abnormal heart sounds which can be either related to disease or benign, and there are several kinds.{{sfn|Davidson's|2010|pp=556–559}} There are normally two heart sounds, and abnormal heart sounds can either be extra sounds, or "murmurs" related to the flow of blood between the sounds. Murmurs are graded by volume, from 1 (the quietest), to 6 (the loudest), and evaluated by their relationship to the heart sounds, position in the cardiac cycle, and additional features such as their radiation to other sites, changes with a person's position, the frequency of the sound as determined by the side of the [[stethoscope]] by which they are heard, and site at which they are heard loudest.{{sfn|Davidson's|2010|pp=556–559}} Murmurs may be caused by [[Valvular heart disease|damaged heart valves]] or congenital heart disease such as [[ventricular septal defect]]s, or may be heard in normal hearts. A different type of sound, a [[pericardial friction rub]] can be heard in cases of pericarditis where the inflamed membranes can rub together.

====Blood tests====
Blood tests play an important role in the diagnosis and treatment of many cardiovascular conditions.

<!--Specific tests-->[[Troponin]] is a sensitive [[biomarker]] for a heart with insufficient blood supply. It is released 4–6 hours after injury and usually peaks at about 12–24 hours.<ref name=OH2010 /> Two tests of troponin are often taken—one at the time of initial presentation and another within 3–6 hours,<ref>{{cite web|last1=Coven|first1=David|last2=Yang|first2=Eric|title=Acute Coronary Syndrome Workup|url=http://emedicine.medscape.com/article/1910735-workup|website=Medscape|access-date=14 August 2016|url-status=live|archive-url=https://web.archive.org/web/20160806121213/http://emedicine.medscape.com/article/1910735-workup|archive-date=6 August 2016}}</ref> with either a high level or a significant rise being diagnostic. A test for [[brain natriuretic peptide]] (BNP) can be used to evaluate for the presence of heart failure, and rises when there is increased demand on the left ventricle. These tests are considered [[biomarker]]s because they are highly specific for cardiac disease.{{sfn|Davidson's|2010|pp=531}} Testing for the [[CK-MB|MB form of creatine kinase]] provides information about the heart's blood supply, but is used less frequently because it is less specific and sensitive.{{sfn|Harrison's|2011|p=1534}}

<!--General tests-->Other blood tests are often taken to help understand a person's general health and risk factors that may contribute to heart disease. These often include a [[full blood count]] investigating for [[anaemia]], and [[basic metabolic panel]] that may reveal any disturbances in electrolytes. A [[coagulation screen]] is often required to ensure that the right level of anticoagulation is given. [[Lipid profile|Fasting lipids]] and [[fasting blood glucose]] (or an [[HbA1c]] level) are often ordered to evaluate a person's [[cholesterol]] and diabetes status, respectively.{{sfn|Davidson's|2010|pp=521–640}}

====Electrocardiogram====
{{main|Electrocardiography}}
[[File:2028 Cardiac Cycle vs Electrocardiogram.jpg|thumb|Cardiac cycle shown against ECG]]
Using surface electrodes on the body, it is possible to record the electrical activity of the heart. This tracing of the electrical signal is the electrocardiogram (ECG) or (EKG). An ECG is a [[bedside test]] and involves the placement of ten leads on the body. This produces a "12 lead" ECG (three extra leads are calculated mathematically, and one lead is [[Ground (electricity)|electrically ground]], or earthed).{{sfn|Davidson's|2010|pp=528–530}}

There are five prominent features on the ECG: the [[P wave (electrocardiography)|P wave]] (atrial depolarisation), the [[QRS complex]] (ventricular depolarisation){{efn|Depolarisation of the ventricles occurs concurrently, but is not significant enough to be detected on an ECG.{{sfn|Davidson's|2010|pp=528–530}}
}} and the [[T wave]] (ventricular repolarisation).<ref name="CNX2014"/> As the heart cells contract, they create a current that travels through the heart. A downward deflection on the ECG implies cells are becoming more positive in charge ("depolarising") in the direction of that lead, whereas an upward inflection implies cells are becoming more negative ("repolarising") in the direction of the lead. This depends on the position of the lead, so if a wave of depolarising moved from left to right, a lead on the left would show a negative deflection, and a lead on the right would show a positive deflection. The ECG is a useful tool in detecting [[arrythmia|rhythm disturbances]] and in detecting insufficient blood supply to the heart.{{sfn|Davidson's|2010|pp=528–530}} Sometimes abnormalities are suspected, but not immediately visible on the ECG. [[Cardiac stress test|Testing when exercising]] can be used to provoke an abnormality or an ECG can be worn for a longer period such as a 24-hour [[Holter monitor]] if a suspected rhythm abnormality is not present at the time of assessment.{{sfn|Davidson's|2010|pp=528–530}}

====Imaging====
{{Main|Cardiac imaging}}
Several [[medical imaging|imaging]] methods can be used to assess the anatomy and function of the heart, including [[ultrasound]] ([[echocardiography]]), [[angiography]], [[CT scan|CT]], [[MRI]], and [[Positron emission tomography|PET, scans]]. An echocardiogram is an ultrasound of the heart used to measure the heart's function, assess for valve disease, and look for any abnormalities. Echocardiography can be conducted by a probe on the chest ([[Transthoracic echocardiogram|transthoracic]]), or by a probe in the [[esophagus]] ([[Transesophageal echocardiogram|transesophageal]]). A typical echocardiography report will include information about the width of the valves noting any [[stenosis]], whether there is any backflow of blood ([[Regurgitation (circulation)|regurgitation]]) and information about the blood volumes at the end of systole and diastole, including an [[ejection fraction]], which describes how much blood is ejected from the left and right ventricles after systole. Ejection fraction can then be obtained by dividing the volume ejected by the heart (stroke volume) by the volume of the filled heart (end-diastolic volume).<ref>{{cite book|author1=Armstrong, William F.|author2=Ryan, Thomas|author3=Feigenbaum, Harvey|title=Feigenbaum's Echocardiography|url=https://books.google.com/books?id=LebU6zLrA8gC|year=2010|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-9557-9|url-status=live|archive-url=https://web.archive.org/web/20160423224258/https://books.google.com/books?id=LebU6zLrA8gC|archive-date=23 April 2016}}</ref> Echocardiograms can also be conducted under circumstances when the body is more stressed, in order to examine for signs of lack of blood supply. This [[cardiac stress test]] involves either direct exercise, or where this is not possible, injection of a drug such as [[dobutamine]].{{sfn|Davidson's|2010|pp=522–536}}

CT scans, [[chest X-rays]] and other forms of imaging can help evaluate the heart's size, evaluate for signs of [[pulmonary oedema]], and indicate whether there is [[pericardial effusion|fluid around the heart]]. They are also useful for evaluating the aorta, the major blood vessel which leaves the heart.{{sfn|Davidson's|2010|pp=522–536}}