Cardiac tumors are abnormal growths of tissue that form within the heart, which can be classified as either non-cancerous (benign) or cancerous (malignant). These growths are further categorized as primary, meaning they originated in the heart itself, or secondary (metastatic), having spread from a primary cancer elsewhere in the body. Understanding the symptoms of these tumors is complicated because they mimic symptoms of much more common heart conditions. The experience of a heart tumor is highly dependent on its size, location, and whether it is disrupting the heart’s mechanical or electrical functions.
Understanding the Rarity of Primary Heart Cancer
Primary heart cancer is exceptionally rare, often considered a medical curiosity. Autopsy studies estimate its prevalence at less than 0.03% of the population. This rarity is partly because heart muscle cells do not divide frequently, making them less susceptible to the mutations that drive cancer growth.
The vast majority of growths found in the heart are not malignant; approximately 75% of primary cardiac tumors are benign. The most common type is the myxoma, a non-cancerous growth that typically develops in the left upper chamber. These benign tumors are dangerous due to their location and potential to cause blockages, not because they are inherently cancerous.
When a malignant tumor is found in the heart, it is far more likely to be secondary, having spread from another site. Metastatic cardiac tumors are estimated to be 20 to 40 times more frequent than primary tumors. Cancers of the lung, breast, melanoma, and lymphoma are among the types most likely to spread to the heart or the surrounding sac. Primary malignant tumors, most often sarcomas like angiosarcoma, are highly aggressive and carry a poor prognosis.
How Heart Tumors Cause Symptoms
The symptoms of a cardiac tumor are diverse and non-specific, often mistaken for common heart disease, anxiety, or a flu-like illness. The symptoms are directly related to how the growth interferes with the heart’s normal function, categorized as mechanical, electrical, and systemic effects. The exact presentation is determined by the tumor’s location, size, and tendency to fragment.
Mechanical Obstruction
A tumor can physically block the flow of blood through the heart chambers or across the heart valves, creating symptoms similar to severe heart failure. If the tumor obstructs the passage of blood into or out of the ventricles, a person may experience shortness of breath, particularly with exertion or when lying flat. Tumors in the right-sided chambers can impede the return of blood to the heart, causing fluid to back up, which may manifest as swelling in the legs, ankles, or abdomen.
The physical blockage can also cause a sudden drop in cardiac output, leading to episodes of lightheadedness or fainting (syncope). Tumor fragments, especially from the common myxoma, can break off and travel through the bloodstream (embolism). If these fragments travel to the brain, they can cause a stroke, presenting with symptoms like slurred speech or weakness.
Electrical Disruption
The heart relies on a precise electrical system to coordinate the pumping action of its four chambers. A tumor growing near the electrical conduction system can interfere with the heart’s natural rhythm generator. This disruption results in various forms of arrhythmia, or irregular heart rhythms, which may be felt as fluttering sensations in the chest (palpitations).
The electrical interference can also slow the heart rate or cause it to beat inefficiently, which contributes to fatigue and dizziness. In some cases, a tumor’s interference can cause a sudden and severe disturbance in the heart’s electrical system, which can result in sudden cardiac arrest.
Systemic Effects
Heart tumors, particularly malignant ones, can cause systemic symptoms beyond direct cardiac effects. These constitutional symptoms are thought to be caused by the tumor releasing inflammatory substances, such as cytokines, into the bloodstream. Patients may report unexplained weight loss, persistent low-grade fever, chills, and profound fatigue.
Pinpointing the Diagnosis
Because the symptoms of a cardiac tumor are so similar to those of many other conditions, imaging is necessary to definitively identify the presence of a mass. The initial, non-invasive imaging test is typically an echocardiogram, which uses sound waves to create moving pictures of the heart. The echocardiogram can show the tumor’s size, its attachment point, its mobility, and how it is affecting blood flow through the heart.
Following initial detection, advanced imaging techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are used. Cardiac MRI offers exceptional detail regarding the soft tissue characteristics of the mass, helping distinguish between different types of tumors and other masses, such as blood clots. CT scans are useful for visualizing the tumor’s extent, its relationship to surrounding structures, and for staging cancer if malignancy is suspected.
Definitive confirmation of a tumor’s malignancy or specific type requires a tissue sample, or biopsy. Obtaining a biopsy from the heart is a challenging and specialized procedure. If a benign tumor like a myxoma is highly suspected and can be completely removed, surgery is often performed immediately without a preliminary biopsy to prevent complications. For suspected malignant tumors that cannot be fully removed, a biopsy is crucial for pathological confirmation and guiding treatment.
Treatment Strategies for Cardiac Tumors
Treatment for a cardiac tumor is highly individualized, depending on whether the mass is benign or malignant, and primary or secondary. For benign tumors, particularly myxomas, surgical removal is the standard and often curative approach. Complete excision eliminates the risk of life-threatening complications, such as blood flow obstruction or embolism.
Treatment for primary malignant tumors, which are aggressive sarcomas, involves a combination of strategies. Surgical resection is attempted whenever possible, but complete removal is often difficult due to the tumor’s invasive nature and critical location. Surgery is frequently combined with systemic therapies, such as chemotherapy and radiation, to address remaining cancer cells and slow progression. Treatment for secondary (metastatic) tumors focuses on the original primary cancer using systemic chemotherapy, often including palliative measures to relieve cardiac symptoms.