Synchronous Cardiac Myxoma and Colorectal Cancer

Abstract

The occurrence of synchronous but unrelated cardiac and colorectal tumors is extremely rare. We present the case of a 56-year-old man who had a left atrial cardiac myxoma that nearly obstructed the mitral valve outflow tract and an unrelated, synchronous colorectal-vesicle carcinoma that nearly obstructed the lumen of the intestine. The patient underwent emergency resection of the cardiac mass under cardiopulmonary bypass and underwent successful resection of the colorectal mass 2 weeks later. Two years after these operations, the patient is well with no recurrence of either tumor.

Synchronous tumors, particularly when one of them involves the heart, require aggressive surgical treatment at multiple sites in order for the patient to survive.

Primary cardiac neoplasms are rare (incidence, <0.2% of all tumors); atrial myxomas constitute approximately 27% of cardiac tumors. ¹ Because of the proximity of the atrial mass to the mitral valve, prolapsing atrial myxomas can cause intermittent obstruction of the valvular outflow tract. Similarly, colorectal cancers can be nearly obstructive at presentation because of their size and location in the intestine. Herein, we present the case of a patient with nearly obstructing, synchronous, but unrelated cardiac and colon tumors. Synchronous tumors of the heart and colon are extremely rare.

Case Report

In September 1997, a 56-year-old man with no notable medical history presented at the emergency room of our institution after experiencing nausea, vomiting, fever, and chills for 4 days. The patient had also experienced dysuria, urgency, and dribbling for 1 week before admission. He was admitted to the hospital with a diagnosis of urinary tract infection. Further interviews with the patient revealed a 5-month history of a decrease in caliber of stools, anorexia, and a 25-pound weight loss. On physical examination, he was found to be in atrial fibrillation, and he had a systolic murmur with no apparent symptoms. The patient was treated with digoxin and intravenous heparin for the atrial fibrillation. A colonoscopy was performed, and a large polypoid mass was found in the sigmoid colon, nearly obstructing the lumen of the intestine. A pediatric colonoscope could not be passed beyond this point.

Because of the cardiac murmur, transthoracic echocardiography was performed, the results of which showed a large intracardiac mass originating in the left atrium and protruding into the left ventricle (Fig. 1). The patient was immediately taken to surgery, and the atrial mass was excised with the patient under mild hypothermic cardiac arrest and on cardiopulmonary bypass. A transseptal biatrial approach was used to resect the atrial mass. The mass partially straddled the mitral valve and had to be eased out of the left ventricle. Sufficient tissue was resected at the base of the tumor stalk to achieve complete resection of the mass with minimal likelihood of recurrence. The septal defect was repaired with autologous pericardium, and the atrial incisions were closed. The heart was resuscitated and the patient was easily weaned from cardiopulmonary bypass. Postoperatively, the patient continued to have atrial fibrillation. Because of the nature of the arrhythmia, endocardial ablation was performed, with subsequent insertion of a permanent pacemaker.

Fig. 1 Transesophageal 4-chamber echocardiogram shows the left atrial mass protruding into the left ventricle and lodged in the mitral valve.

Microscopic examination of the 7- × 4- × 3.2-cm specimen showed gelatinous tissue consistent with a benign cardiac myxoma; there were focal areas of hem-orrhage, central necrosis, and acute inflammation. The specimen margins were free of tumor cells, which indicated that excision of the cardiac tumor was complete.

Within 2 weeks of discharge from the hospital after the cardiac surgery, the patient was readmitted and underwent resection of a 10-cm sigmoid colon mass, diagnosed as a mucinous adenocarcinoma. Involvement with the posterior wall of the urinary bladder necessitated a partial cystectomy with insertion of a suprapubic drainage catheter. Staging of the tumor yielded a modified Dukes' classification of B-2.

The patient recovered well and was subsequently discharged from the hospital. He was following a regular diet and was walking. At the last follow-up in November 1998, echocardiography and colonoscopy showed no recurrence of either tumor. The patient had returned to full employment as of June 2000.

Discussion

The medical literature contains descriptions of left atrial myxomas prolapsing into the mitral valve and creating an intermittent obstruction of the left heart. In 1 series, ² 44% of the patients presented with signs and symptoms of obstructive valvular disease. The literature also describes cases of colorectal carcinomas that present late as partial or complete intestinal obstruction. ³ Moreover, some rectal adenocarcinomas metastasize to the right ventricle of the heart and partially obstruct its outflow tract. ⁴ However, to our knowledge, there are no previously published papers that describe the synchronous occurrence of an atrial myxoma with colorectal carcinoma, especially one in which both tumors were nearly obstructive. There is no established association between cardiac myxomas and colorectal neoplasms. Of interest, however, is the fact that regardless of the type of cancer, the incidence of 2nd and 3rd neoplasms in cancer patients is higher than can be accounted for by chance alone. ⁵

A complex presentation of synchronous tumors should prompt the surgeon to treat the most immediate life-threatening problem first. In patients such as ours, a nearly obstructing cardiac mass of the left heart should take precedence over a nearly obstructing colorectal cancer if the patient does not have a bowel obstruction. Surgical excision of the cardiac mass should be carried out immediately. ⁶ Clear surgical margins can usually be obtained. The mass in the colon can then be resected as soon as the altered hemodynamics have been corrected; delay can be as long as a few postoperative weeks. The surgeon must balance the patient's need to recover from cardiac surgery with the necessity of halting further growth of the neoplasm. Alternatively, there may be a situation in which the cardiac problem is urgent, but concurrent partial or complete intestinal obstruction is present and the colon is unprepped. In this case, emergency surgical resection of the colorectal tumor should be performed first, with a proximal colostomy and the formation of a distal rectal pouch.

Complications can occur in patients undergoing surgery for either of these types of tumors. For example, when such patients are placed on cardiopulmo-nary bypass, the administration of 20,000 to 30,000 U of intravenous heparin may precipitate bleeding. Gastrointestinal bleeding may occur because of vascular ischemia in an area with an already existing, ulcerated neoplasm. ⁷ Acute visceral ischemia might result from embolization of a left-sided cardiac myxoma to the femoral arterial system or to the visceral vasculature, which could, in turn, lead to sudden intestinal bleeding. ^8,9 When a patient is becoming hemodynamically unstable and intestinal bleeding persists despite the correction of existing coagulopathy with clotting factors, emergency resection of the colorectal tumor before cardiac surgery is warranted (as stated above). Alternatively, resection of both the cardiac and the colon tumor can be performed under the same anesthetic. However, in the usual emergency situation, colon resection is considered secon-dary to the cardiac emergency. Only after the cardiac myxoma has been successfully removed and the pa-tient has stabilized hemodynamically should the patient's bowel be prepped and an intestinal anastomosis be performed.

Conclusions

To our knowledge, this is the 1st report in the English medical literature of a cardiac obstructive mass and a synchronous colorectal obstructive mass. Although the cardiac myxoma is generally considered the most urgent and is resected first, bowel resection should be performed under the same anesthetic if the intestinal mass is creating an obstruction or causing heavy bleeding. If the colon is not obstructed, a later, more definitive, intestinal resection and anastomosis may be planned.