Angina pectoris 狭心症
a syndrome characterized by paroxysmal,
constricting pain below the sternum, most easily
precipitated by exertion or excitement and caused
by ischemia of the heart muscle, usually due to a
coronary artery disease, as arteriosclerosis.
Angina: (語源) any attack of painful spasms characterized by
sensations of choking or suffocating. < L angina quinsey, for *
ancina < Gk strangulation, hanging
病態
治療原則
男性、中年
季節:冬
寒冷暴露
次の有名な絵を見て,
狭心症の発作につながる
因子を挙げよ
大食後
重い荷物
階段登り
タバコ
前胸部痛
図4-2 心筋酸素需要・供給と狭心症の病態
収縮力
血圧(後負荷)
心拍数
左心室圧
心室容積
酸素
供給
酸素
需要
冠動静脈酸素含有量の較差
心筋酸素分布
冠血流量
大動脈圧
(拡張期)
冠血管抵抗
壁張力
静脈還流(前負荷)
虚血
自覚症状
狭心痛
心電図異常
代謝障害
心室機能不全
ST下降(労作性狭心症)
乳酸・H+ の産生
壁運動異常
ST上昇(安静時狭心症)
K +の漏出
拡張終期圧上昇
不整脈
アデノシン遊離
心拍出量低下
狭心痛の
部位と放散
心拍出量の分配率と酸素消費
臓器
脳
心臓
肝臓
腎臓
骨格筋
皮膚
その他
全身
血流量
O2消費量
ml/ 分(臓器100g当たり)
ml/ 分(全臓器当たり)
分配率(%)ml/ 分(全臓器当たり)
消費率(%)
57
750
15
46
20
70
200
4
27
11
95
1,350
27
33
14
420
1,200
24
16
7
3
850
16
70
30
7
350
7
5
2
400
7
36
16
5,100
100
233
100
動脈血には20 vol% の酸素が含まれている
O2 extraction vol% CaO2 – CvO2
心臓11.5%,脳6.4、肝臓4.1、腎臓1.3、
骨格筋静止時4.3、最大運動時17.2
Lead V4 at rest (top) and after 4.5 min of exercise (bottom).
There is 0.3 mV of horizontal ST-segment depression,
indicating a positive test for ischemia.
Coronary
Angiography
Stenosis: narrowing
of the artery,
due most likely to
atherosclerosis.
Damage to the intima due to atherosclerosis is a major
cause of thrombosis in the arteries.
The resultant ischemia of the myocardium can lead to
ischemic necrosis, i.e., an infarct [Myocardial Infarction].
1.What therapeutic agent can be used to lyse the clots in coronary
vessels?
冠動脈硬化
Coronary
atherosclerosis
内膜下のプラーク生成
血栓生成の可能性
Spasm発生の可能性
冠動脈血栓
Coronary
thrombosis
内皮細胞機能
血小板
マクロファージ
増殖型平滑筋細胞
図2-20参照、さらに病理学で学んでください。
Dynamic coronary obstruction
Spasm
Rest angina
tone
tone
Dynamic coronary obstruction
• This figure shows how the caliber of
eccentric coronary artery stenoses may
change, with considerable variation in the
degree of stenosis resistance and the
propensity to produce angina.
• Both increased vascular tone (first two
examples, spasm & tone ) and decreased
vascular tone (third example) are depicted.
狭心症 angina pectoris の分類 (p.139)
安定狭心症
器質性(労作性)
Stable (typical) angina
プリンツメタル型狭心症 Prinzmetal (variant) angina
冠動脈攣縮型(異型)
不安定狭心症
梗塞前
Unstable (crescendo) angina
安定狭心症
・安定プラークによる冠状動脈
(LAD,LCX,RCA)の内腔狭窄
『酸素需要>酸素供給』→休息により改善
冠動脈攣縮
spasm
血管平滑筋の過剰収縮
冠血管狭窄
冠血流量減少
プリンツメタル型狭心症
•冠状動脈のspasm (攣縮)による
(plaque プラークの近傍)
•休息・睡眠時
←運動・血圧・心拍数に無関係
•喫煙がリスクファクター
•より若年で発症。予後比較的良好。
•ST-segment elevation ←貫壁性の虚血
不安定狭心症 (Preinfarction angina)
・不安定プラークの崩壊
(アテローム内出血、機械的ストレス↑)
→血栓形成・Vasospasm→一時的内腔閉塞
・心筋梗塞へ移行しやすい
→動脈硬化病変が不安定であり、
続発性の血栓形成が起こりやすい
・頻度が増大、発作の延長。休息時にも起こる。
動脈硬化から
見た狭心症
閉塞性血栓 1
白色血栓症
動脈壁の異常
血小板とフィブリ
ンが主役
閉塞性血栓 2
赤色血栓症
プラークの破綻
凝固因子が主役
図4-1冠動脈硬化およびスパスムと狭心症治療薬の位置付け
中膜
血栓症の可能性
平滑筋層
(収縮・弛緩)
内皮
内腔
内膜
冠拡張薬
Ca拮抗薬
K + チャネル開口薬
など
脂質・
アテローム
冠動脈スパスム(攣縮)
β遮断薬
動脈硬化(器質的狭窄)
亜硝酸化合物、抗血小板薬
抗脂血症
治療薬
Correction of the imbalance
increasing delivery (by increasing coronary flow)
nitrates (nitroglycerin)
vasodilators (Ca antagonists, KCOs)
coronary bypass grafts or angioplasty (PTCA)
percutaneous transcatheter coronary
angioplasty
decreasing oxygen demand (by decreasing cardiac
work)
b-blockes, nitrates
nitrates (nitroglycerin)
vasodilators (Ca antagonists, KCOs)
図4-2 心筋酸素需要・供給と狭心症の病態
収縮力
血圧(後負荷)
心拍数
左心室圧
心室容積
酸素
供給
酸素
需要
冠動静脈酸素含有量の較差
心筋酸素分布
冠血流量
大動脈圧
(拡張期)
冠血管抵抗
壁張力
small oxygen debt: extract about
75% of available oxygen
‘tachycardia’-- harmful
静脈還流(前負荷)
虚血
自覚症状
狭心痛
心電図異常
ST下降(労作性狭心症)
代謝障害
+
乳酸・H の産生
心室機能不全
ST上昇(安静時狭心症)
K +の漏出
拡張終期圧上昇
不整脈
アデノシン遊離
心拍出量低下
壁運動異常
冠状動脈の分岐(A)と血流量変化(B).
時間 (秒)
心周期中に冠状動脈の血流は変化する。 2本の点線の
間は心室の拍出期で、大動脈圧は高いが、左心室の内圧がさらに高い
ために左冠状動脈の血流は減少している。(図15-24,生理学テキスト)
Artery blocked by
thrombus on fissured
atherosclerotic plaque
Zone of perfusion
(area at risk)
next
Myocardium
0 hr
2 hr
24 hr
Obstructed
coronary art.
Endocardium
area
at risk
Zone of
necrosis
Zone of
necrosis
Epicardium
Progression of myocardial necrosis after coronary
artery occlusion.
Necrosis begins in a small zone of the
myocardium beneath the endocardial surface in the center of the
ischemic zone.
This entire region of myocardium (dashed outline) depends on
the occluded vessel for perfusion and is the area at risk.
Note that a very narrow zone of myocardium immediately beneath the
endocardium is spared from necrosis because it can be oxygenated by
Principle of stress
radionuclide imaging
for the detection of
coronary artery
disease.
(1) a normal coronary
artery and an artery with
significant stenosis (top),
(2) the myocardial
territory (perfusion
image), and
(3) the ventricular wall
(wall motion image)
supplied by each artery.
Distribution of regional
myocardial blood flow
• The distribution of regional myocardial
blood flow in the myocardium is
heterogeneous, i.e., there is less blood
flowing in the ischemic myocardial bed
(blue area) than in the normal myocardial
bed.
Coronary blood flow at rest and during stress
(x ~5)
最大運動時
Coronary blood flow at rest and during stress (1)
At rest, coronary blood flow is similar in the normal artery
and in the artery with stenosis.
Resting coronary blood flow in the diseased artery is
maintained at a normal level and is sufficient to meet
resting metabolic myocardial demands because of
recruitment of coronary reserve (dilatation of the resistance
vasculature) in the distal coronary bed.
During exercise, myocardial metabolic demands increase
and more myocardial nutrient blood flow is required.
Coronary reserve is increased as a result of dilatation of the
coronary resistance vessels in the peripheral coronary bed.
Coronary blood flow at rest and during stress (2)
In the territory of the normal coronary artery, the resistance
vessels dilate and coronary blood flow is increased by 2 to
2.5 times.
In the abnormal coronary bed, which is distal to the
significant coronary stenosis, resistance vessels are already
dilated and little if any further dilatation is possible.
Increased metabolic demands thus cannot be met, and the
relatively hypoperfused myocardium becomes ischemic.
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狭心症 - 機能薬理学分野