Editing Heart failure (section)

===Left-sided failure===
The left side of the heart takes oxygen-rich blood from the lungs and pumps it to the rest of the [[circulatory system]] in the body (except for the [[pulmonary circulation]]). Failure of the left side of the heart causes blood to back up into the lungs, causing breathing difficulties and fatigue due to an insufficient supply of oxygenated blood. Common respiratory signs include [[tachypnea|increased respiratory rate]] and labored breathing (nonspecific signs of shortness of breath). [[Rales]] or crackles are heard initially in the lung bases and when severe in all [[lung fields]] indicate the development of [[pulmonary edema]] (fluid in the [[Pulmonary alveolus|alveoli]]). [[Cyanosis]], indicates [[hypoxemia|deficiency of oxygen in the blood]], is a late sign of extremely severe pulmonary edema.<ref>{{cite book | vauthors = Adeyinka A, Kondamudi NP | chapter = Cyanosis |date=2022 | chapter-url = http://www.ncbi.nlm.nih.gov/books/NBK482247/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29489181 |access-date=2022-05-11 |archive-date=13 March 2021 |archive-url=https://web.archive.org/web/20210313021701/https://www.ncbi.nlm.nih.gov/books/NBK482247/ |url-status=live }}</ref>

Other signs of left ventricular failure include a laterally displaced [[apex beat]] (which occurs when the heart is enlarged) and a [[gallop rhythm]] (additional heart sounds), which may be heard as a sign of increased blood flow or increased intracardiac pressure. [[Heart murmur]]s may indicate the presence of valvular heart disease, either as a cause (e.g., [[aortic stenosis]]) or as a consequence (e.g., [[mitral regurgitation]]) of heart failure.<ref>{{Cite web |title=Heart Murmur: Types & Causes |url=https://my.clevelandclinic.org/health/diseases/17083-heart-murmur |access-date=2022-05-11 |website=Cleveland Clinic |archive-date=28 November 2022 |archive-url=https://web.archive.org/web/20221128033026/https://my.clevelandclinic.org/health/diseases/17083-heart-murmur |url-status=live }}</ref>

''Reverse'' insufficiency of the left ventricle causes congestion in the blood vessels of the lungs so that symptoms are predominantly respiratory. Reverse insufficiency can be divided into the failure of the left atrium, the left ventricle, or both within the left circuit. Patients will experience [[dyspnea|shortness of breath (dyspnea)]] on exertion and, in severe cases, dyspnea at rest. Increasing breathlessness while lying down, called [[orthopnea]], also occurs. It can be measured by the number of pillows required to lie comfortably, with extreme cases of orthopnea forcing the patient to sleep sitting up. Another symptom of heart failure is [[paroxysmal nocturnal dyspnea]]: a sudden nocturnal attack of severe shortness of breath, usually occurring several hours after falling asleep.<ref>{{Cite web |title=What is Exercise Intolerance? |url=https://www.webmd.com/fitness-exercise/what-to-know-about-exercise-intolerance |access-date=2022-05-11 |website=WebMD |language=en |archive-date=11 May 2022 |archive-url=https://web.archive.org/web/20220511094156/https://www.webmd.com/fitness-exercise/what-to-know-about-exercise-intolerance |url-status=live }}</ref> There may be "[[cardiac asthma]]" or [[wheezing]]. Impaired left ventricular ''forward'' function can lead to symptoms of poor systemic perfusion such as [[dizziness]], [[confusion]], and cool extremities at rest. Loss of consciousness may also occur due to loss of blood supply to the brain.<ref>{{cite web |title=Heart Failure Signs and Symptoms |url=https://www.heart.org/en/health-topics/heart-failure/warning-signs-of-heart-failure |website=heart.org |publisher=American Heart Association |access-date=16 November 2022 |archive-date=17 November 2022 |archive-url=https://web.archive.org/web/20221117045606/https://www.heart.org/en/health-topics/heart-failure/warning-signs-of-heart-failure |url-status=live }}</ref>