Hydatid Disease Affecting the Heart and Aorta - Erler Zimmer
Clinical History
This 11-year-old female had an 18-month history of hydatid disease, with a total of 17 cysts removed from the brain during three craniotomies. Subsequently, cysts were discovered in the kidneys, mesentery, and abdominal aorta at its bifurcation. X-ray of the heart revealed a calcified cyst, leading to a referral to a tertiary hospital for its removal. Unfortunately, the patient's health deteriorated, and she passed away following open-heart surgery, during which a dead hydatid cyst was found in the left ventricle.
Pathology
The heart specimens, with the left ventricle laid open, and the aorta at its common iliac bifurcation show atheromatous depositions in the upper portion of the aorta. Antemortem clotting is present at the iliac bifurcation, extending down both common iliac arteries. The heart displays left ventricular wall hypertrophy, and an abnormal communication exists between the left ventricle and atrium, running through the posterior cusp of the mitral valve via the papillary muscle into the left ventricular cavity. This channel is surrounded by thickened fibrous-looking tissue, and the posterior cusp of the valve has been split. Surgical incisions are visible on the posterior aspect of the specimen, ventricular wall, and in the left atrial appendage. Hydatid cysts are found in the abdominal aorta at its bifurcation and in the channel joining the left ventricle and left atrium. Histology reveals cysts within the aorta wall, comprising three layers: an outermost pericyst fibrous layer, a middle ectocyst layer that is laminated, hyaline, and acellular, and an inner endocyst in the germinative layer, consisting of daughter cysts and brood capsules with scolices. A focal granulomatous palisading reaction is also present within the aorta wall.
Further Information
Hydatid cyst is caused by the larval stage of the cestode tapeworm Echinococcus granulosus, found in the gut of dogs, its definitive hosts. Human infection occurs through ingestion of ova in contaminated vegetables or water with dog faeces. Hydatid disease is endemic in cattle-raising regions, including the Mediterranean countries, the Middle East, South America, Australia, and New Zealand. Although hydatid cysts can affect various body parts, they are most common in the liver and lungs. Cardiac involvement is rare but potentially fatal, representing 0.5–2% of all hydatid cases. The complications and presentation vary based on cyst location, size, and integrity. Left ventricular myocardium is frequently involved. The reduction in hydatid transmission in Australia is attributed to the widespread use of the cestocidal drug praziquantel in dog all-wormers and the availability of inexpensive commercial dry dog food.
