心包填塞 | 醫學影像學習園地

心包填塞 Cardiac tamponade

/ 王幸婷 陳傑龍 謝博堯 江品儀

定義(Definition)

An accumulation of pericardial fluid under pressure, leading to impaired cardiac filling and hemodynamic compromise

介紹(Introduction)

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正常的心包膜是一層fibroelastic sac containing a thin layer of fluid,當心包膜腔內累積大量液體(pericardial effusion),或者當pericardium受到損傷或變的不那麼有彈性時,就有可能會產生pericardial compressive syndromes(Cardiac tamponadeConstrictive pericarditisEffusive-constrictive pericarditis)
cardiac tamponade,演進的過程中,pericardial pressure上升壓迫心臟腔室,但正常的pericardium有一定的彈性,可以緩衝這些壓力,當到達極限後,心臟便須開始對抗這外在的壓力。若持續進展,心臟腔室受壓迫變小,而舒張期的順應性也降低(reduced diastolic compliance),造成心臟充填不足,進而產生接續的臨床症狀甚至死亡。

病因(Etiology)

Major causes of pericardial disease
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症狀(Symptoms and signs)

臨床症狀的產生跟pericardial fluid累積的時間跟速度有關:
1. Acute cardiac tamponade:數分鐘內發生,可能是因為外傷(trauma),大血管或心臟破裂(rupture of the heart or aorta)complication of an invasive diagnostic or therapeutic procedure,會產生胸悶、胸痛,喘、呼吸急促,嚴重會心因性休克(cardiogenic shock),需要緊急降低pericardial pressure (pericardiocentesis)
2. Subacute cardiac tamponade
:數天到數周內發生,可能與癌症(neoplastic),尿毒症(uremic)或心內膜炎(idiopathic pericarditis)。因為演進的較慢,病人在早期可能沒有症狀,但壓力到達一定程度後,可能產生呼吸困難(dyspnea),胸悶(chest discomfort or fullness),四肢水腫(peripheral edema),容易疲累(fatigability)等症狀。
3. Low pressure (occult) cardiac tamponade
:在嚴重低血容積(hypovolemic)的病人身上可能產生。
4. Regional cardiac tamponade
:與loculated effusionlocalized hematoma有關,可能指壓迫到某幾個腔室。
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診斷(Diagnosis)

臨床上可看到:
1.Beck’s triad
(1)
低血壓(Hypotension):乃因心充填下降 -> 心輸出下降造成,病人會有四肢冰冷,發紺,跟尿量減少等症狀,嚴重會產生cardiogenic shock
(2)
頸靜脈壓上升(Elevated jugular venous pressure)、頸靜脈擴張(Jugular-venous distension):心臟腔室壓力受壓迫而上升,造成靜脈回流受阻(impaired venous return to the heart)
(3)Muffled heart sound—fluid inside the pericardium
2.
心跳上升
3.
四肢水腫:因靜脈回流受阻,病人也可能有水腫的情況。
4.Pulsus paradoxus
:正常情況下,吸氣時血壓會稍微降低,而呼氣時血壓會稍微上升,下降的正常範圍是<10 mmHg,如果下降的幅度>10 mmHg則稱為pulsus paradoxus。理學檢查上的發現:聽診器可聽到心跳但在radial artery摸不到pulse
5.Negative Kussmaul's sign (the absence of an inspiratory decline in jugular venous pressure)
6.Pericardial rub
A pericardial rub may be heard in patients with cardiac tamponade due to inflammatory pericarditis

檢驗檢查:
1.EKGsinus tachycardialow voltageElectrical alternans
2.CXR
Cardiomegaly (>200ml)
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3.心臟超音波:雖然cardiac tamponade是一個臨床診斷,但two dimensionalDoppler echocardiography可以幫助判斷pleural effusion的存在,以及其對hemodynamic的影響
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(1)Chamber collapse—Collapse of any cardiac chamber, but usually the right sided chambers, occurs when intrapericardial pressure exceeds intracardiac pressure within a particular chamber
(2)Diastolic collapse of the right atrium—At end-diastole (during atrial relaxation), the RA volume is minimal, but pericardial pressure is maximal, causing the RA to buckle. RA collapse, especially when it persists for more than one-third of the cardiac cycle, is highly sensitive and specific for cardiac tamponade. In contrast, brief RA collapse can occur in the absence of cardiac tamponade
(3)Diastolic collapse of the right ventricle—RV diastolic collapse occurs in early diastole when the RV volume is still low. Less sensitive sign for the presence of cardiac tamponade but is very specific for cardiac tamponade
(4)Left sided chamber collapse—Left atrial collapse is seen in about 25 percent of patients with hemodynamic compromise and is very specific for cardiac tamponade. Left ventricular collapse is less common, since the wall of the left ventricle is more muscular
(5)Respiratory variation in volumes and flows—Reciprocal changes in left and right ventricular volumes occur during inspiration, the ventricular and atrial septa move leftward, a process reversed with expiration. These changes play a central role in the pathogenesis of pulsus paradoxus

治療(Treatment)

1.Definitive treatment - Drainage of the pericardial effusion
2.
hemodynamic stable conservatively treatment, with careful monitoring, serial echocardiographic studies, avoidance of volume depletion, and therapy aimed at the underlying cause of the pericardial effusion.

參考資料(Reference)

1.Acute Cardiac Tamponade, David H. Spodick, N Engl J Med 2003; 349:684-690
2.Uptodate: Cardiac tamponade
3.Harrison's Principles of Internal Medicine, 18e