Cardiology/ja: Difference between revisions

'''循環器学'''（''じゅんかんきがく'''、{{ety|grc|''καρδίᾱ'' (kardiā)|heart||-''λογία'' ([[wikt:-logia|-logia]])|study}}）は、心臓に関する学問である。循環器学は、[[heart/ja|心臓]]および[[cardiovascular system/ja|心血管系]]の障害を扱う[[medicine/ja|医学]]の一分野である。この分野には、[[congenital heart defect/ja|先天性心疾患]]、[[coronary artery disease/ja|冠動脈疾患]]、[[heart failure/ja|心不全]]、[[valvular heart disease/ja|心臓弁膜症]]、[[electrophysiology/ja|電気生理学]]の[[medical diagnosis/ja|診断]]と治療が含まれる。この分野を専門とする[[physician/ja|医師]]は'''循環器専門医'''と呼ばれ、[[internal medicine/ja|内科]]の一分野である。小児循環器専門医は循環器学を専門とする[[pediatrician/ja|小児科医]]である。心臓外科を専門とする医師は'''[[cardiothoracic surgeon/ja|心臓胸部外科医]]'''または'''心臓外科医'''と呼ばれ、[[general surgery/ja|一般外科]]の専門分野である。

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[[Hypertension]], also known as "high blood pressure", is a [[Chronic (medicine)|long term]] [[Disease|medical condition]] in which the [[blood pressure]] in the [[artery|arteries]] is persistently elevated. High blood pressure usually does not cause symptoms. Long term high blood pressure, however, is a major risk factor for [[coronary artery disease]], [[stroke]], [[heart failure]], [[peripheral vascular disease]], [[vision loss]], and [[chronic kidney disease]].

Lifestyle factors can increase the risk of hypertension. These include [[Salt and cardiovascular disease|excess salt]] in the diet, [[overweight|excess body weight]], [[smoking]], and alcohol consumption. Hypertension can also be caused by other diseases, or occur as a side-effect of drugs.

Blood pressure is expressed by two measurements, the [[Systole (medicine)|systolic]] and [[diastolic]] pressures, which are the maximum and minimum pressures, respectively. Normal blood pressure when at rest is within the range of 100–140 [[Millimeter of mercury|millimeters mercury]] (mmHg) systolic and 60–90 mmHg diastolic. High blood pressure is present if the resting blood pressure is persistently at or above 140/90 mmHg for most adults. Different numbers apply to children. When diagnosing high blood pressure, [[ambulatory blood pressure monitoring]] over a 24-hour period appears to be more accurate than "in-office" [[blood pressure measurement]] at a physician's office or other blood pressure screening location.

Lifestyle changes and medications can lower blood pressure and decrease the risk of health complications. Lifestyle changes include weight loss, decreased salt intake, physical exercise, and a healthy diet. If changes in lifestyle are insufficient, [[blood pressure medication]]s may be used. A regimen of up to three medications effectively controls blood pressure in 90% of people. The treatment of moderate to severe high arterial blood pressure (defined as >160/100 mmHg) with medication is associated with an improved [[life expectancy]] and reduced [[morbidity]]. The effect of treatment for blood pressure between 140/90&nbsp;mmHg and 160/100&nbsp;mmHg is less clear, with some studies finding benefits while others do not. High blood pressure affects between 16% and 37% of the population globally. In 2010, hypertension was believed to have been a factor in 18% (9.4 million) deaths.

==== Essential vs Secondary hypertension ====

{{Main|Essential hypertension|Secondary hypertension}}

Essential hypertension is the form of [[hypertension]] that by definition has no identifiable cause. It is the most common type of hypertension, affecting 95% of hypertensive patients, it tends to be familial and is likely to be the consequence of an interaction between [[Environment (biophysical)|environmental]] and [[genetics|genetic]] factors. [[Prevalence]] of essential hypertension increases with [[Ageing|age]], and individuals with relatively high blood pressure at younger ages are at increased risk for the subsequent development of hypertension.

Hypertension can increase the risk of [[cerebrum|cerebral]], [[cardiac]], and [[renal]] events.

[[Secondary hypertension]] is a type of [[hypertension]] which is caused by an identifiable underlying secondary cause. It is much less common than essential hypertension, affecting only 5% of hypertensive patients. It has many different causes including [[endocrine diseases]], [[kidney diseases]], and [[tumors]]. It also can be a [[Adverse effect|side effect]] of many [[medications]].

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==== Complications of hypertension ====

[[Image:Main complications of persistent high blood pressure.svg|thumb|right|250px|Main complications of persistent [[high blood pressure]]]]

{{Main|Complications of hypertension}}

[[Complications of hypertension]] are clinical outcomes that result from [[hypertension|persistent elevation]] of blood pressure. Hypertension is a risk factor for all clinical manifestations of [[atherosclerosis]] since it is a risk factor for atherosclerosis itself. It is an independent predisposing factor for [[heart failure]], [[coronary artery disease]], [[stroke]], [[renal disease]], and [[peripheral arterial disease]]. It is the most important [[risk factor]] for [[cardiovascular]] [[morbidity]] and [[mortality rate|mortality]], in [[industrialized countries]].

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=== Congenital heart defects ===

{{Main|Congenital heart defect}}

A congenital heart defect, also known as a "congenital heart anomaly" or "congenital heart disease", is a problem in the structure of the heart that is present at [[childbirth|birth]]. Signs and symptoms depend on the specific type of problem. Symptoms can vary from none to life-threatening. When present they may include rapid breathing, [[cyanosis|bluish skin]], poor weight gain, and feeling tired. It does not cause chest pain. Most congenital heart problems do not occur with other diseases. Complications that can result from heart defects include [[heart failure]].

The cause of a congenital heart defect is often unknown. Certain cases may be due to infections during [[pregnancy]] such as [[rubella]], use of certain medications or drugs such as [[ethanol|alcohol]] or [[tobacco]], parents being closely related, or poor nutritional status or [[obesity]] in the mother. Having a parent with a congenital heart defect is also a risk factor. A number of genetic conditions are associated with heart defects including [[Down syndrome]], [[Turner syndrome]], and [[Marfan syndrome]]. Congenital heart defects are divided into two main groups: [[cyanotic heart defect]]s and [[non-cyanotic heart defect]]s, depending on whether the child has the potential to turn bluish in color. The problems may involve the interior walls of the heart, the [[heart valves]], or the large blood vessels that lead to and from the heart.

Congenital heart defects are partly preventable through [[rubella vaccination]], the adding of [[iodine]] to salt, and the adding of [[folic acid]] to certain food products. Some defects do not need treatment. Other may be effectively treated with [[catheter procedure|catheter based procedures]] or [[cardiac surgery|heart surgery]]. Occasionally a number of operations may be needed. Occasionally [[heart transplantation]] is required. With appropriate treatment outcomes, even with complex problems, are generally good.

Heart defects are the most common [[birth defect]]. In 2013 they were present in 34.3 million people globally. They affect between 4 and 75 per 1,000 live births depending upon how they are diagnosed. About 6 to 19 per 1,000 cause a moderate to severe degree of problems. Congenital heart defects are the leading cause of birth defect-related deaths. In 2013 they resulted in 323,000 deaths down from 366,000 deaths in 1990.

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==== Tetralogy of Fallot ====

[[Tetralogy of Fallot]] is the most common congenital heart disease arising in 1–3 cases per 1,000 births. The cause of this defect is a [[ventricular septal defect]] (VSD) and an [[overriding aorta]]. These two defects combined causes deoxygenated blood to bypass the lungs and going right back into the circulatory system. The [[modified Blalock-Taussig shunt]] is usually used to fix the circulation. This procedure is done by placing a graft between the subclavian artery and the ipsilateral pulmonary artery to restore the correct blood flow.

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==== Pulmonary atresia ====

[[Pulmonary atresia]] happens in 7–8 per 100,000 births and is characterized by the aorta branching out of the right ventricle. This causes the deoxygenated blood to bypass the lungs and enter the circulatory system. Surgeries can fix this by redirecting the aorta and fixing the right ventricle and pulmonary artery connection.

There are two types of pulmonary atresia, classified by whether or not the baby also has a [[ventricular septal defect]].

* Pulmonary atresia with an intact ventricular septum: This type of pulmonary atresia is associated with complete and intact [[septum]] between the ventricles.

* Pulmonary atresia with a ventricular septal defect: This type of pulmonary atresia happens when a ventricular septal defect allows blood to flow into and out of the right ventricle.

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==== Double outlet right ventricle ====

[[Double outlet right ventricle]] (DORV) is when both great arteries, the pulmonary artery and the aorta, are connected to the right ventricle. There is usually a VSD in different particular places depending on the variations of DORV, typically 50% are subaortic and 30%. The surgeries that can be done to fix this defect can vary due to the different physiology and blood flow in the defected heart. One way it can be cured is by a VSD closure and placing conduits to restart the blood flow between the left ventricle and the aorta and between the right ventricle and the pulmonary artery. Another way is systemic-to-pulmonary artery shunt in cases associated with [[Pulmonic stenosis|pulmonary stenosis]]. Also, a [[Atrial septostomy|balloon atrial septostomy]] can be done to relieve hypoxemia caused by DORV with the Taussig-Bing anomaly while surgical correction is awaited.

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==== Transposition of great arteries ====

[[File:D-tga-575px.jpg|thumb|Dextro-transposition of the Great Arteries]]

There are two different types of [[Transposition of the great vessels|transposition of the great arteries]], [[Dextro-Transposition of the great arteries|Dextro-transposition of the great arteries]] and [[Levo-Transposition of the great arteries|Levo-transposition of the great arteries]], depending on where the chambers and vessels connect. Dextro-transposition happens in about 1 in 4,000 newborns and is when the right ventricle pumps blood into the aorta and deoxygenated blood enters the bloodstream. The temporary procedure is to create an [[atrial septal defect]]. A permanent fix is more complicated and involves redirecting the pulmonary return to the right atrium and the systemic return to the left atrium, which is known as the [[Senning procedure]]. The [[Rastelli procedure]] can also be done by rerouting the left ventricular outflow, dividing the pulmonary trunk, and placing a conduit in between the right ventricle and pulmonary trunk. Levo-transposition happens in about 1 in 13,000 newborns and is characterized by the left ventricle pumping blood into the lungs and the right ventricle pumping the blood into the aorta. This may not produce problems at the beginning, but will eventually due to the different pressures each ventricle uses to pump blood. Switching the left ventricle to be the systemic ventricle and the right ventricle to pump blood into the pulmonary artery can repair levo-transposition.

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==== Persistent truncus arteriosus ====

[[Persistent truncus arteriosus]] is when the [[truncus arteriosus]] fails to split into the aorta and pulmonary trunk. This occurs in about 1 in 11,000 live births and allows both oxygenated and deoxygenated blood into the body. The repair consists of a VSD closure and the Rastelli procedure.