Arteriosclerosis - Doumyakukouka (English spelling)

Japanese: 動脈硬化 - どうみゃくこうか（英語表記）Arteriosclerosis

What is the disease?

Arteries play an important role in carrying oxygen and nutrients to every corner of the body. As we age, these arteries lose their elasticity and become hard, and various substances are deposited in the arteries, narrowing the blood vessels and impeding blood flow. This condition is called arteriosclerosis.

Arteriosclerosis is: Porridge-like ( College ) Hardening, 2 Arterioles ( Saidou Myaku ) Hardening, ③ Tunica media ( Chumaiku ) There are three types of sclerosing. Arteries are made up of three layers: the intima, the media, and the adventitia. In type ①, changes occur mainly in the intima of large or medium-sized arteries, while in type ③, the media mainly changes. On the other hand, type ② is a hardening of small peripheral arteries. Types ① and ② are clinically problematic.

What is the cause?

Atherosclerosis, which is the most clinically important, is a hardening that occurs in relatively large arteries such as the aorta, cerebral arteries, and coronary arteries, and is caused by the buildup of fats such as cholesterol in the inner lining of the arteries. Atheroma ( Juicy ) The atheroma gradually thickens and narrows the lumen of the artery (Figure 26). When the atheroma ruptures, a blood clot forms and the artery becomes completely blocked.

Bad cholesterol (LDL cholesterol), which causes atheroma, is found in large amounts in animal fats. On the other hand, good cholesterol (HDL cholesterol) has the effect of suppressing arteriosclerosis. Neutral fats are also said to promote arteriosclerosis. Neutral fat levels rise when you consume sugar or alcohol.

Arteriosclerosis is a type of arteriosclerosis in which small arteries in the brain and kidneys harden and blood flow stagnates. It is caused by prolonged high blood pressure.

The causes of or progression of arteriosclerosis are called "risk factors." Hyperuricemia ( Congratulations on your graduation ) Causes include obesity, lack of exercise, stress, and genetic predisposition.

Furthermore, these risk factors are interrelated, and as the number of factors increases, the risk of arteriosclerosis increases exponentially. Reducing these risk factors is extremely important for both treatment and prevention.

Diseases that are prone to arteriosclerosis

Atherosclerosis can occur in arteries throughout the body, but we will briefly explain the areas and diseases in which it is particularly likely to occur.

For more information, see the section on each disease.

① Stroke

Stroke is cerebral infarction ( Noise ) or cerebral hemorrhage ( Dispatch ) This is a general term for diseases caused by impaired blood flow in the blood vessels of the brain.

When blood flow is impaired due to cerebral arteriosclerosis, it can cause dizziness, headaches, tinnitus, memory loss, short tempers, and irritability. Symptoms such as dementia are also more likely to appear. If blood flow is completely cut off, it will cause cerebral infarction, and if fragile blood vessels rupture and bleed, it will cause cerebral hemorrhage.

②Angina pectoris , myocardial infarction

When arteriosclerosis occurs in the coronary arteries that carry oxygen and nutrients to the heart, the blood flow to the heart decreases, causing chest pain and shortness of breath during exercise. This is called angina pectoris. If the plaque ruptures and the coronary artery becomes completely blocked by a blood clot, this is called myocardial infarction.

③Aortic aneurysm

Aortic aneurysm is a swelling of the aorta in the chest or abdomen caused by arteriosclerosis. The swelling gradually grows and eventually bursts, causing massive bleeding and death.

④Nephrosclerosis

If high blood pressure continues for a long period of time, the small arteries in the kidneys will harden, causing kidney function to decline. You will wake up several times at night to urinate, and you will produce a lot of pale urine. High blood pressure can suddenly worsen.

⑤ Arteriosclerosis obliterans

When arteriosclerosis occurs in the arteries of the lower limbs and blood flow is restricted, the legs may become numb, feel cold, or become painful when walking.

Testing and diagnosis

Risk factors are searched for. First, blood pressure is measured to check for high blood pressure. Blood tests are used to measure the amount of cholesterol, neutral fat, sugar, and uric acid in the blood to check for dyslipidemia, diabetes, hyperuricemia, etc. Pulse Wave Propagation ( Myaku is starch ) By measuring the rate at which blood flow to the arteries increases, the degree of arteriosclerosis can be estimated.

Furthermore, tests are performed to identify the area where arteriosclerosis is occurring. Fundus examination is performed to check for changes in the retinal arteries. If arteriosclerosis is found in the retina, there is a possibility that the same degree of arteriosclerosis is occurring in the arteries of the brain.

neck ( celebrate ) Atherosclerosis of the arteries, aorta, renal arteries and lower limb arteries is diagnosed by CT, MRI and ultrasound, and may require angiography. Coronary artery sclerosis is diagnosed by exercise stress testing and cardiac catheterization.

Treatment methods

First, removing risk factors by changing lifestyle habits such as diet and exercise is important for treating and preventing diseases caused by arteriosclerosis.

① Exercise

Obesity accelerates the progression of arteriosclerosis, so it is important to be careful not to overeat and to be physically active on a daily basis. Walking or light jogging every day reduces neutral fats and increases good cholesterol, which has preventive and therapeutic effects against arteriosclerosis. Exercise also helps prevent high blood pressure and diabetes.

②Dietary therapy

Be careful not to consume too much animal fats such as meat, eggs, and butter, which can hasten the onset and progression of arteriosclerosis. Use vegetable fats such as margarine and salad oil, and increase your protein intake from fish and soybeans.

Blue fish such as sardines, mackerel, and pacific saury have the effect of lowering cholesterol and neutral fat in the blood and preventing blood from clotting. Dietary fiber also prevents cholesterol absorption in the small intestine and helps to excrete it. It is found in large amounts in vegetables such as burdock, seaweed, mushrooms, and konjac, and helps prevent obesity.

Too much salt can lead to high blood pressure, and too much sugar can lead to diabetes, so you need to be careful. Drink alcohol in moderation, and it's best to quit smoking.

3) Drug treatment

The most important drug treatment for arteriosclerosis is drugs that lower cholesterol. Recently, drugs that reliably lower cholesterol, such as HMGCoA reductase inhibitors, have been widely used. Antiplatelet drugs are also used to prevent blood vessels from clogging. Drug treatment for high blood pressure, diabetes, and hyperuricemia is also important.

④ Surgical treatment

When the lumen of blood vessels has been narrowed by plaque, bypass surgery or catheter-based vasodilation therapy may be used to restore blood flow.

Ikeda Uichi

Figure 26 Mechanism of atherosclerosis
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Figure 26 Mechanism of atherosclerosis

Source: Houken “Sixth Edition Family Medicine Encyclopedia” Information about the Sixth Edition Family Medicine Encyclopedia

Japanese:

どんな病気か

　体のすみずみまで酸素や栄養素を運ぶ重要な役割を果たしているのが動脈です。この動脈が年齢とともに老化し、弾力性が失われて硬くなったり、動脈内にさまざまな物質が沈着して血管が狭くなり、血液の流れが滞る状態を動脈硬化といいます。

　動脈硬化は、①粥状(じゅくじょう)硬化、②細動脈(さいどうみゃく)硬化、③中膜(ちゅうまく)硬化の3種類に分類されます。動脈は内膜、中膜、外膜の三層からなっていますが、①は太い、または中等度の太さの動脈の内膜に、③は中膜に主に変化が起きます。一方、②は末梢の細い動脈が硬化するものです。臨床的に問題になるのは①と②です。

原因は何か

　臨床的に最も重要である粥状硬化は、大動脈、脳動脈、冠動脈など比較的太い動脈に起こる硬化で、動脈の内膜にコレステロールなどの脂肪からなる粥腫(じゅくしゅ)（アテローム）ができ、次第に肥厚することで動脈の内腔が狭くなります（図26）。粥腫が破れると血栓がつくられ、動脈は完全にふさがります。

　粥腫のもとになる悪玉コレステロール（LDLコレステロール）は、動物性脂肪に多く含まれています。一方、善玉コレステロール（HDLコレステロール）は、動脈硬化を抑える作用があります。中性脂肪も動脈硬化を促すといわれています。中性脂肪値は、糖分やアルコールの摂取などで上昇します。

　細動脈硬化は、脳や腎臓のなかの細い動脈が硬化して血液が滞る動脈硬化です。高血圧が長く続いて引き起こされます。

　動脈硬化を起こしたり、進めたりする原因を“危険因子”と呼びます。脂質異常症（高脂血症）、高血圧、糖尿病、喫煙、高尿酸血症(こうにょうさんけっしょう)、肥満、運動不足、ストレス、遺伝素因などがあげられます。

　また、これらの危険因子は相互に関係しており、因子が増えれば雪ダルマ式に動脈硬化の危険性が高まります。治療にも予防にも、これらの危険因子を減らすことが大変重要です。

動脈硬化が起こりやすい病気

　動脈硬化は全身の動脈で起こりますが、とくに起こりやすい部位と病気を簡単に説明します。

　詳しくは、それぞれの病気の項をみてください。

①脳卒中(のうそっちゅう)

　脳卒中は、脳梗塞(のうこうそく)や脳出血(のうしゅっけつ)など脳の血管の血流障害によって起こる病気の総称です。

　脳の動脈硬化により血流障害が起こると、めまい、頭痛、耳鳴りが生じ、記憶力が低下し、気が短くなったり、怒りっぽくなります。ボケなどの症状も現れやすくなります。完全に血流が途絶えると脳梗塞に、もろくなった血管が破れて出血すると脳出血になります。

②狭心症(きょうしんしょう)、心筋梗塞(しんきんこうそく)

　心臓に酸素や栄養素を運んでいる冠動脈に動脈硬化が起こると、心臓の血流量が減るため、運動時に胸の痛みや息苦しさを感じるようになります。これが狭心症です。さらに粥腫が破れて冠動脈が血栓で完全に詰まった状態になった場合を心筋梗塞といいます。

③大動脈瘤(だいどうみゃくりゅう)

　動脈硬化により胸部や腹部の大動脈の一部がふくれてこぶのようになったものを大動脈瘤といいます。こぶが徐々に大きくなり、ついに破裂して大出血を起こし、死亡することがあります。

④腎硬化症(じんこうかしょう)

　高血圧が長期間続くと腎臓のなかの細い動脈に硬化が起こり、腎機能が衰えてきます。夜間に何度も小便に起きるようになり、色の薄い尿がたくさん出ます。高血圧が急にひどくなることもあります。

⑤閉塞性動脈硬化症(へいそくせいどうみゃくこうかしょう)

　動脈硬化が下肢の動脈に起こり、血流が滞ると、足がしびれたり、冷たく感じたり、歩行中に痛くなったりします。

検査と診断

　危険因子の検索を行います。まず、血圧測定で高血圧の有無を調べます。血液検査では、血液中のコレステロール、中性脂肪、糖、尿酸の量を測定し、脂質異常症、糖尿病、高尿酸血症などがあるかどうかを調べます。血液の流れる速度（脈波伝搬(みゃくはでんぱん)速度）を測定することにより動脈硬化の程度を推定することができます。

　さらに、動脈硬化の起こっている部位を特定するための検査を行います。眼底検査により網膜の動脈の変化をみます。網膜に細動脈硬化がみられる場合は、ほぼ同程度の細動脈硬化が脳の動脈にも起こっている可能性があります。

　頸(けい)動脈、大動脈、腎動脈や下肢動脈の粥状硬化は、CT、MRIや超音波検査で調べます。血管造影検査が必要な場合もあります。冠動脈の硬化は、運動負荷検査や心臓カテーテル検査で調べます。