什么意思？

Traumatic hemopericardium can develop after both blunt and penetrating chest injuries. In contrast to chronic effusions, in which 600 mL of pericardial fluid may not cause hemodynamic depression, even small accumulations of blood after acute injury result in cardiac tamponade with significant hypotension and cardiac arrest. Inflow occlusion of the atrioventricular valves, resulting from external compression by pericardial blood, leads to decreased ventricular filling, especially in the right heart. Because a relatively small amount of fluid accumulation can cause major hemodynamic changes, evacuation of even a minimal quantity of blood from the pericardium usually restores BP . Hypotensive patients who may have cardiac tamponade could benefit from pericardiocentesis. Transthoracic echocardiography (TTE) or TEE in intubated patients without suspected esophageal injury can aid in diagnosing and evacuating pericardial blood. Diastolic collapse, defined as approximation of the (usually right) ventricular walls during diastole, is a sign of tamponade and is associated with systemic BP reductions of 15%–20%. During evacuation, simultaneous imaging of the needle and the pericardial sac prevents cardiac perforation.

胸部钝挫伤和穿透伤后均可发生创伤性心包积血。在慢性积液中，600mL的心包液可能不会导致血流动力学抑制，与之相反，即使是急性损伤后的少量积血也会导致心脏压塞，并伴有严重的低血压和心脏骤停。由于心包血液的外压导致房室瓣膜的流入闭塞，导致心室充盈减少，尤其是在右心。因为相对少量的液体积聚会引起较大的血流动力学变化，即使从心包中排出极少量的血液，通常也能恢复血压。可能有心脏压塞的低血压患者可以从心包穿刺术中获益。对无可疑食管损伤的插管患者进行经胸超声心动图(TTE)或经胸超声心动图(TEE)检查，有助于诊断和排空心包血液。舒张期塌陷，定义为舒张期接近心室壁(通常是右心室壁)，是填塞的征兆，与全身血压降低15%-20%有关。在排气过程中，针头和心包囊同时成像可防止心脏穿孔。

approximation of the (usually right) ventricular walls 是啥意思？谢谢