Tumors involving the heart are rare in cats and dogs. The most common heart tumor is hemangiosarcoma of the right atrium. Other cardiac tumors include chemodectoma, ectopic thyroid carcinoma, various sarcomas, lymphoma (especially cats), and benign tumors such as myxomas.
Right atrial hemangiosarcoma is a highly malignant tumor that causes clinical signs because of pericardial effusion and cardiac tamponade. Hemorrhage into the pericardial sac causes pressure on the heart which decreases the ability of the heart to effectively pump blood. The most common signs are collapse, weakness, and exercise intolerance. The metastatic risk is very high with common sites including the lungs, spleen, liver, kidneys, and brain.
Heart masses and their location (right atrial, right atrial appendage, or heart base) are diagnosed with echocardiography, however echocardiographic findings are not usually sufficient to differentiate tumor types. Other tests include ECG and pericardiocentesis with cytology (usually unrewarding with only 8% of samples being diagnostic), pH measurements of pericardial fluid (controversial with malignant effusions having a pH > 7.5), and measurements of pericardial fluid concentrations of cardiac troponin I.
Abdominal ultrasound or CT scan is recommended to evaluate the spleen, liver, kidneys and other abdominal organs. In one clinical study, 29% of 31 dogs with right atrial hemangiosarcoma had concurrent splenic hemangiosarcoma and 42% had evidence of intra-abdominal metastasis to a non-splenic site. Thoracic radiographs or CT scans are recommended to assess for metastasis to the lungs.
Treatment options for dogs with right atrial hemangiosarcoma include palliative options, such as repeated pericardiocentesis and pericardiectomy, medical management with Yunnan Baiyao and/or aminocaproic acid, chemotherapy, or resection of the right atrial appendage (with or without pericardial grafting) via an open or thoracoscopic approach. Because of the high risk of metastasis for dogs with right atrial hemangiosarcoma, postoperative chemotherapy is recommended using doxorubicin-based protocols.
The prognosis for dogs with right atrial hemangiosarcoma is poor. The median survival times are 14.5 days for dogs treated with pericardiocentesis, 18 days for dogs treated with Yunnan Baiyao alone or in combination with aminocaproic acid, 16 days for dogs treated with pericardiectomy alone, 118 days for dogs treated with right atrial appendage resection, and 175 days for dogs treated with pericardiectomy and chemotherapy.
In contrast to dogs with cardiac hemangiosarcoma, the outcomes are much better for dogs with either aortic body tumors or mesotheliomas treated with pericardiectomy alone. The median survival time for dogs with mesothelioma treated with pericardiectomy is 414 days with 1- and 2-year survival rates of 80% and 40%, respectively; and the median survival time for dogs with aortic body tumors treated with pericardiectomy is 730 days.
Last updated on 6th March 2017