Thoracoabdominal Compartment Syndrome

As we advance our knowledge in understanding abdominal compartment syndrome, it is worth going back to revisit our basic embryologic development of the main determinant of the abdominal and thoracic cavities, i.e., the diaphragm. The abdominal and thoracic cavities used to be one cavity at some stage of the embryonic life — “intraembryonic coelom” — before the “septum transversum” — diaphragmatic origin — divided it into two cavities. Therefore, if a condition develops that will impair the diaphragm from separating the cavities, leading to the possibility of pressures to transmit from one cavity to another, this becomes relevant as abdominal compartment syndrome. Diaphragmatic eventration is a congenital developmental defect in the muscular portion of the diaphragm with preserved attachments to the sternum, ribs, and dorsolumbar spine, leading to a semi-membranous diaphragm that anatomically separates the two cavities, but not physiologically. In the case of high abdominal pressure, the pressure will transmit to the thoracic cavity, causing derangement in both the anatomy and physiology. This was reported and named “Thoracoabdominal Compartment Syndrome”.

Caval foramen hernia in a cat

Case summary A 3-year-old neutered female domestic shorthair cat presented for a 2-week history of hyporexia, lethargy and weight loss. Aspartate aminotransferase, alanine aminotransferase and cholesterol were mildly elevated. Thoracic radiographs identified a lobulated soft tissue opacity in the caudal thorax to the right of midline, with the border effacing the caudal vena cava and broad-based towards the diaphragm. The broad base was suggestive of diaphragmatic hernia, with the other radiographic features and location suggestive of caval foramen hernia. Ultrasound confirmed diaphragmatic hernia with liver herniation. CT showed the herniation of multiple liver lobes and the gallbladder through a defect at the caval foramen. Herniorrhaphy was performed via ventral midline coeliotomy. Following this procedure, the cat’s clinical signs resolved and its weight has been regained. Relevance and novel information To our knowledge, this is the first report of successful caval foramen herniorrhaphy in a cat. Caval foramen hernia is a type of congenital diaphragmatic hernia. The authors suggest that its embryopathology involves defective septum transversum development. The case was detected during the standard diagnostic investigation of non-specific clinical signs. Its radiographic findings may easily be mistaken for a pulmonary mass. Although not seen in our case, caval foramen hernia is commonly associated with caudal vena cava obstruction, which can potentially result in Budd–Chiari-like syndrome.

Peritoneopericardial diaphragmatic hernia in the dog and cat

Peritoneopericardial diaphragmatic hernia (PPDH) is a congenital communication between the pericardial sac and the abdominal cavity allowing displacement of abdominal organs to the pericardial sac. Peritoneopericardial diaphragmatic hernia is thought to occur due to a failure of the development of septum transversum. Vomiting, exercise intolerance and respiratory distress are the most common clinical signs. Diagnosis of PPDH is based on plain radiography. Physical examination and diagnostic imaging may detect the presence of other congenital anomalies. Surgical repair of the PPDH is the treatment of choice for animals with clinical signs. Prognosis following surgical repair of PPDH is favorable. Animals with no clinical signs related to PPDH may not undergo surgical repair.

Diaphragmatic hernia in an adult cadaver: a case report

Introduction: The diaphragm is a musculofibrous structure that separates the thoracic cavity from the abdominal cavity. Although it is a continuous sheet, developmental^ it is derived from four different sources: the septum transversum, pleuroperitoneal membranes, lateral and dorsal body wall and the mesentery of oesophagus. Methodology: During routine dissection for undergraduate students in the department of Anatomy, Kasturba Medical College, Manipal a rare variation was encountered in a 65 year old female cadaver. Results: We observed a large defect in the left anterolateral aspect of the diaphragm with associated left pulmonary hypoplasia. The muscular contribution to the diaphragm from the left lateral and dorsal body wall was absent leading to the herniation of abdominal contents into the left thoracic cavity which included the stomach, intestinal loops, left colic flexure and the spleen. Conclusion: Diaphragmatic hernias presenting in adult life are rare and most commonly associated with a history of trauma. Congenital diaphragmatic hernia may remain asymptomatic as in the present case which is extremely rare and could be a chance finding during a routine chest x-ray. Knowledge of this anatomic defect in the diaphragm presenting in adult life would help prevent further complications leading to gastrointestinal or pulmonary distress.

Conditional deletion of WT1 in the septum transversum mesenchyme causes congenital diaphragmatic hernia in mice

Congenital diaphragmatic hernia (CDH) is a severe birth defect. Wt1-null mouse embryos develop CDH but the mechanisms regulated by WT1 are unknown. We have generated a murine model with conditional deletion of WT1 in the lateral plate mesoderm, using the G2 enhancer of the Gata4 gene as a driver. 80% of G2-Gata4Cre;Wt1fl/fl embryos developed typical Bochdalek-type CDH. We show that the posthepatic mesenchymal plate coelomic epithelium gives rise to a mesenchyme that populates the pleuroperitoneal folds isolating the pleural cavities before the migration of the somitic myoblasts. This process fails when Wt1 is deleted from this area. Mutant embryos show Raldh2 downregulation in the lateral mesoderm, but not in the intermediate mesoderm. The mutant phenotype was partially rescued by retinoic acid treatment of the pregnant females. Replacement of intermediate by lateral mesoderm recapitulates the evolutionary origin of the diaphragm in mammals. CDH might thus be viewed as an evolutionary atavism.