血液為什麼會往下跑？認識靜脈瓣膜與逆流
How venous valves and reflux work
中文版
腿部的血液要對抗重力回到心臟，靠的是小腿肌肉擠壓和靜脈裡一扇扇像單向門的瓣膜。
當瓣膜關不緊，血液就容易往下回流。時間久了，血管承受的壓力增加，慢慢變粗、變彎。
- 瓣膜像單向門，幫助血液往上走
- 關不緊時會出現逆流
- 逆流不一定只靠外觀判斷，要用超音波確認
1.正常的瓣膜怎麼工作？
- 走路時，小腿肌肉像幫浦一樣把血液往上推。
- 瓣膜打開讓血液通過，再關起來避免往下流。
2.瓣膜關不緊會怎樣？
- 血液反覆往下回流，形成壓力。
- 表淺靜脈逐漸擴張、彎曲。
- 久站時可能更沉重、痠脹或腫。
💡 正常回流與靜脈逆流
| 比較 | 正常回流 | 靜脈逆流 |
|---|---|---|
| 瓣膜 | 可以關緊 | 關閉不完全 |
| 血液方向 | 往心臟方向 | 部分往下回流 |
| 血管壓力 | 較穩定 | 逐漸增加 |
| 結果 | 血管外觀較正常 | 可能形成靜脈曲張 |
⚠️ 溫馨提醒：光看青筋無法知道逆流從哪裡開始。若症狀影響生活，可以用站立式下肢靜脈超音波把原因弄清楚。
ENGLISH
Blood in the legs travels against gravity to return to the heart. Calf-muscle movement and small venous valves help it move upward.
When a valve does not close properly, blood flows backward. Pressure builds and the vein may enlarge and twist.
- Valves act like one-way doors
- Poor closure allows backward flow, called reflux
- Ultrasound is used to locate reflux
1.How healthy valves work
- Walking activates the calf-muscle pump and pushes blood upward.
- Valves open to let blood pass, then close to prevent backward flow.
2.What happens when a valve leaks?
- Blood repeatedly flows backward and increases pressure.
- Superficial veins gradually enlarge and twist.
- Heaviness, aching or swelling may worsen after standing.
💡 Normal return and venous reflux
| Comparison | Normal return | Venous reflux |
|---|---|---|
| Valve | Closes properly | Does not close completely |
| Blood direction | Toward the heart | Partly flows downward |
| Pressure | More stable | Gradually increases |
| Result | Vein remains more normal | Varicose veins may develop |
Note: Appearance alone cannot show where reflux begins. Standing leg-vein ultrasound can clarify the cause.
References
- De Maeseneer MG, et al. ESVS 2022 Clinical Practice Guidelines. Eur J Vasc Endovasc Surg. 2022;63:184–267. 查看來源
本文提供一般衛教，不取代個別診斷或治療。若有急性不舒服，請先就近就醫。
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