Adverse hemodynamic effects and echocardiographic consequences of pericardial closure soon after sternotomy and pericardiotomy.

The acute hemodynamic and echocardiographic effects of pericardial closure on cardiac function were studied in 11 pigs during steady-state anesthesia and ventilation. Observations were made after sternotomy, both while the pericardium was open and after it had been closed, and then after closure of the chest, after the pericardium had been reopened by removing the pericardial suture through the chest wall. In five pigs, further observations were made when a suture was tightened to close the pericardium while the chest remained closed. Closure of the pericardium when the chest was open reduced cardiac output by 14% and mean stroke volume by 19% (both p less than 0.05). Systemic vascular resistance increased by 15% when the pericardium was closed while the chest was open (NS), and increased by 19% when it was closed while the chest was closed (p less than 0.05). Heart rate did not change significantly, and the systemic blood pressure was maintained (-8%, NS). All these effects were reversed by opening the pericardium. Intrathoracic epicardial echocardiographic monitoring of the left ventricle showed that its end-diastolic dimension increased (by 11%, p less than 0.05) when the pericardium was opened. After chest closure, paradoxical motion of the interventricular septum was consistently demonstrated only during ventilation, and it was not related to whether or not the pericardium was open. This study suggests that cardiac function may be impaired by pericardial closure after cardiac surgery because of some degree of constriction of the heart chambers, although acute circulatory responses compensate for the mild decrease in stroke volume. Monitoring of blood pressure alone cannot document the subtle circulatory changes induced by pericardial closure, and therefore it is not a reliable guide to decisions of whether to close the pericardium or leave it open in individual patients.