Definition and Overview
Improvements in cardiac imaging techniques and cardiopulmonary bypass have enabled the successful diagnosis and treatment of various intracardiac tumours. Primary tumours of the heart may either be benign or malignant and both are considered rare conditions, occurring in less than 1% of the population. The majority (70%) of these intracardiac tumours are benign.
Who Should Undergo and Expected Results
The most frequently encountered primary intracardiac tumour is a myxoma, which is responsible for approximately half of all benign primary intracardiac tumours. Myxomas, which are most commonly seen in adult women in their 30s to 60s, arise from the endocardium and typically extend into a chamber of the heart. They can usually be found in the left atrium, arising from the atrial septum but can also be located in the right atrium. A small percentage of myxomas are found in the ventricles and most are pedunculated lesions that are often friable.
Aside from myxomas, other benign intracardiac tumours include
- Rhabdomyomas, which are the most common heart tumour in children
- Lipomas, which are composed of adipose tissues
- Fibromas, which tend to become calcified
- Papillary fibroelastomas, which are tumours of the heart valves
Primary malignant tumours occur less frequently, and are associated with limited survival. These tumours include angiosarcomas and rhabdomyosarcomas.
Cardiac tumours present in various ways and are generally determined by the location of the mass inside the heart. Tumours with an intramyocardial location can produce rhythm abnormalities, occasionally resulting in sudden cardiac death. Meanwhile, tumours located inside cardiac cavities can result in obstruction of blood flow, which can produce symptoms similar to valvular heart disease. Myxomas, for example, are typically located in the left atrium and restrict the filling of the left ventricle, resulting in symptoms similar to mitral stenosis, such as dyspnea, orthopnea, and heart failure. Its location on the left side of the heart makes it prone to systemic embolisation, which occurs in more than 30% of affected individuals. Less frequently, patients with intracardiac tumours present with constitutional symptoms. These are usually non-specific, such as fever and loss of weight.
The outcomes of excision of myxomas and other benign lesions under cardiopulmonary bypass are generally good. Morbidity and mortality are low, typically less than 5% and the recurrence of the tumour is not common. Meanwhile, patients with malignant cardiac tumours typically have a poor prognosis. Surgical resection, if performed, is palliative only, and additional chemotherapy after the operation is recommended.
How is the Procedure Performed?
Once an intracardiac tumour is diagnosed and work-up reveals that the mass is resectable, the patient is prepared for surgery. The excision of the intracardiac tumour is performed under cardiopulmonary bypass.
After the induction of general anaesthesia and sterile prepping, a median sternotomy is performed, followed by a standard bicaval cannulation. Cardiopulmonary bypass is initiated, the aorta is clamped, and the heart is arrested. Given that most cardiac tumours are located in the left atrium, the approach performed usually involves an incision over the left atrium. If the mass is difficult to visualise, an additional incision may be done over the right atrium.
The complete resection of the tumour is then performed and is removed as a whole mass (en bloc) as much as possible. Many surgeons recommend excision of the base of the tumour along with part of the atrial septum or wall, especially if the pedicle is wide. Some margin of normal atrial tissue is typically resected to ensure that the margins are negative. This minimises the risk of recurrence. The resultant defect is then closed primarily, if possible. In some cases where the defect is quite large, a patch made of pericardium or polytetrafluoroethylene may be used to close the defect. For tumours located in the ventricle, the pedicle is usually transected without excision of the ventricular wall where it is attached.
After the tumour is removed, the remaining structures are inspected, making sure that no additional tumours are present. If no other lesions are noted and if the tumour has not caused any significant damage to the valves, the heart is then closed. The heart is de-aired and weaning off cardiopulmonary bypass is performed. After adequate hemostasis, the chest is closed using sternal wires.
Possible Risks and Complications
Cardiopulmonary bypass in itself has several associated risks. These include bleeding requiring reoperation, renal failure, myocardial infarction, and air embolism resulting in stroke, to name a few. However, when performed by trained specialists, the risk of developing these complications is low.
Some risks are specific for intracardiac tumours. An arrhythmia known as atrial fibrillation is quite common. Other conduction abnormalities may also occur, and are typically caused by the resection of significant amounts of the atrial wall or septum. Tumour embolism can likewise occur, which is usually attributed to mechanical manipulation of the heart during the procedure. Caution is advised when manipulating the heart prior to the application of the aortic cross-clamp to minimise this risk.
Although rare, a myxoma can recur. The recurrence rate has been estimated to range from 1% to 3%. The sporadic type of myxoma recurs after approximately 2 years. Recurrence does not necessarily occur in the same chamber as the initial tumour. The familial type of myxoma is associated with a higher risk of recurrence, with recurrence rates as high as 20-25%. This kind of myxoma needs to be managed more aggressively, and the recurrence needs to be resected. Follow-up echocardiography is thus recommended after the procedure.
- TSRA Review of Cardiothoracic Surgery
- Sabiston and Spencer Surgery of the Chest, 7th edition
- Mastery of Cardiothoracic Surgery, 2nd edition
- Kirklin and Barratt-Boyes Cardiac Surgery