Editing Electrocardiography (section)

==Diagnosis==
Numerous diagnoses and findings can be made based upon electrocardiography, and many are discussed above. Overall, the diagnoses are made based on the patterns. For example, an "irregularly irregular" QRS complex without P waves is the hallmark of [[atrial fibrillation]]; however, other findings can be present as well, such as a [[bundle branch block]] that alters the shape of the QRS complexes. ECGs can be interpreted in isolation but should be applied – like all [[diagnostic tests]] – in the context of the patient. For example, an observation of peaked T waves is not sufficient to diagnose hyperkalemia; such a diagnosis should be verified by measuring the blood potassium level. Conversely, a discovery of hyperkalemia should be followed by an ECG for manifestations such as peaked T waves, widened QRS complexes, and loss of P waves. The following is an organized list of possible ECG-based diagnoses.<ref>{{cite journal |last1=Montague |first1=Brian T. |last2=Ouellette |first2=Jason R. |last3=Buller |first3=Gregory K. |title=Retrospective Review of the Frequency of ECG Changes in Hyperkalemia |journal=Clinical Journal of the American Society of Nephrology |date=March 2008 |volume=3 |issue=2 |pages=324–330 |doi=10.2215/CJN.04611007 |pmid=18235147 |pmc=2390954 }}</ref>

Rhythm disturbances or arrhythmias:<ref>{{Cite web |date=2018-02-19 |title=Arrhythmia |url=https://www.nhs.uk/conditions/arrhythmia/ |access-date=2022-10-28 |website=nhs.uk |language=en}}</ref>
* [[Atrial fibrillation]] and [[atrial flutter]] without rapid ventricular response
* [[Premature atrial contraction]] (PACs) and [[premature ventricular contraction]] (PVCs)
* [[Sinus arrhythmia]]
* [[Sinus bradycardia]] and [[sinus tachycardia]]
* [[Sinus pause]] and [[sinoatrial arrest]]
* [[Sinus node dysfunction]] and [[bradycardia-tachycardia syndrome]]
* [[Supraventricular tachycardia]]
** [[Atrial fibrillation]] with rapid ventricular response
** [[Atrial flutter]] with rapid ventricular response
** [[AV nodal reentrant tachycardia]]
** [[Atrioventricular reentrant tachycardia]]
** [[Junctional ectopic tachycardia]]
** [[Atrial tachycardia]]
*** [[Ectopic atrial tachycardia]] (unicentric)
*** [[Multifocal atrial tachycardia]]
*** [[Paroxysmal atrial tachycardia]]
** Sinoatrial nodal reentrant tachycardia
* [[Wide complex tachycardia]]
** [[Ventricular flutter]]
** [[Ventricular fibrillation]]
** [[Ventricular tachycardia]] (monomorphic ventricular tachycardia)
** [[Torsades de pointes]] (polymorphic ventricular tachycardia)
* [[Pre-excitation syndrome]]
** [[Lown–Ganong–Levine syndrome]]
** [[Wolff–Parkinson–White syndrome]]
* [[J wave]] (Osborn wave)

[[Heart block]] and conduction problems:
* [[Sinoatrial block]]: first, second, and third-degree
* AV node
** [[First-degree AV block]]
** [[Second-degree AV block]] (Mobitz [Wenckebach] I and II)
** [[Third-degree AV block]] or complete AV block
* Right bundle
** [[Right bundle branch block#Incomplete right bundle branch block|Incomplete right bundle branch block]] (IRBBB)
** Complete [[right bundle branch block]] (RBBB)
* Left bundle
** Incomplete left bundle branch block (ILBBB)
** Complete [[left bundle branch block]] (LBBB)
** [[Left anterior fascicular block]] (LAFB)
** [[Left posterior fascicular block]] (LPFB)
** [[Bifascicular block]] (LAFB plus LPFB)
** [[Trifascicular block]] (LAFP plus FPFB plus RBBB)
* QT syndromes
** [[Brugada syndrome]]
** [[Short QT syndrome]]
** [[Long QT syndrome]]s, genetic and drug-induced
* Right and left atrial abnormality

Electrolytes disturbances and intoxication:
* [[Digoxin poisoning|Digitalis intoxication]]
* Calcium: [[hypocalcemia]] and [[hypercalcemia]]
* Potassium: [[hypokalemia]] and [[hyperkalemia]]
* [[Serotonin Syndrome|Serotonin toxicity]]

Ischemia and infarction:
* [[Wellens' syndrome]] (LAD occlusion)
* de Winter T waves (LAD occlusion) <ref>{{Cite journal |last=de Winter |first=Robert |s2cid=205040240 |date=6 Nov 2008 |title=A New ECG Sign of Proximal LAD Occlusion |journal=NEJM |volume=359 |issue=19 |pages=2071–2073 |doi=10.1056/NEJMc0804737 |pmid=18987380|doi-access=free }}</ref>
* [[ST elevation]] and [[ST depression]]
* [[High frequency QRS]] changes
* [[Myocardial infarction]] (heart attack)
** Non-Q wave myocardial infarction
** [[NSTEMI]]
** [[STEMI]]
** [[Sgarbossa's criteria]] for ischemia with a [[left bundle branch block|LBBB]]

Structural:
* [[Acute pericarditis]]
* [[Right ventricular hypertrophy|Right]] and [[left ventricular hypertrophy]]
* [[Right ventricular strain]] or S1Q3T3 (can be seen in [[pulmonary embolism]])

Other phenomena:
* [[Cardiac aberrancy]]
** [[Ashman phenomenon]]
* [[Concealed conduction]]
*[[Electrical alternans]]