The pleura and pericardium are very close anatomical companions within the thorax. Both contain minimal levels of physiological fluid. It is quiet common to find combined pleural and pericardial effusion. While the commonest explanation for combination of pleural and pericardial effusion is inflammation of both in systemic disorders like polyserositis or malignancy . In cardiac failure also both effusions can occur explained by raised venous pressure.
But there has always been a curious relationship between these two spaces.
Is there a antomical or physiological link between these two spacs ? In fact a large pleural effusion some times result in sympathetic pericardial effusion. Tapping of pleural effusion may regress this pericardial fluid as well.
This is purely a clinical observation and needs an explanation .It is believed , there is some non functional lymphatic channels shared between pericardial and pleural spaces.This may get opened up in pathology of either of them.
Dr.S.Venkatesan MD 