Trapped Lung Secondary to Cardiomegaly in a 78 year‐old Male with Congestive Heart Failure

Abstract

Introduction/ObjectiveAlthough the etiologies of both trapped lung and cardiomegaly are well‐established, co‐presentation of the two conditions, and possible interactions between them, are much rarer. The objective of this report is to describe our findings during cadaver dissection, consider possible interactions between the two conditions, and discuss issues related to decision‐making for imaging and clinical interventions.Case ReportDuring routine dissection of a 78 year‐old male cadaver we found a trapped left lung and enlarged heart almost completely occupying the left pleural cavity. The subject's past medical history included heart failure, hypertension, and pleural effusion, and was consistent with a diagnosis of both conditions. A trapped lung is a shrunken lung surrounded by a cortex of fibrotic visceral pleura, typically formed as a consequence of chronic pleural effusion. This subject's left lung was deformed, and markedly diminished compared with the right lung, particularly in the lower lobe. His cardiothoracic ratio was 0.54, consistent with a diagnosis of cardiomegaly. Ventricular wall thickness measurements indicated substantial biventricular hypertrophy. During the final week of his life he underwent multiple chest radiographs showing persistent opacification of the left pleural cavity and the presence of pleural effusion. Both before and after thoracentesis neither the trapped lung, nor the enlarged heart, were identified.Clinical Considerations/ConclusionsWas the presence of both a trapped lung and enlarged heart in the present subject a coincidence, or was there some sort of causation? Although no direct causal connection has been established between the two conditions, analogies can be found in the literature. Compression of the heart on the left lung due to post‐surgical edema after coronary artery bypass grafting has been shown to cause decreased gas volumes in the lower lobe. Conversely, after pneumonectomy, the increased afterload resulting from a decreased pulmonary vascular bed has been shown to cause right ventricular hypertrophy. It is possible that similar mechanisms played a role in the development of either the trapped lung or enlarged heart in the present subject.This subject may have benefitted from earlier identification of his trapped lung in the years prior to his death. This would have offered additional treatment options, such as surgical decortication. Early identification also would have prevented the cost, discomfort and risks of repeat thoracentesis. Thoracentesis is not recommended in the case of trapped lung, as the pleural cavity will immediately refill due to the negative pleural pressure. Greater awareness, and a higher overall index of suspicion among clinicians for the presence of trapped lung and its sequelae, would lead to more routine use of CT scans in similar cases, and likely overall improved, and potentially more efficient, patient care.Support or Funding InformationN/A