Muhammad Aboudan, MD; Ahmad Fadel, MD; Muhammad Wahiduzzaman, MD; Ahmed Ibrahimbacha, MD

Right atrial thrombosis is a serious and potentially fatal condition if left untreated. Therefore, early detection and treatment are critical for preventing complications. Although widespread use of two- dimensional echocardiography has led to an increase in the number of diagnosed cases of right atrial thrombosis, the frequency of this entity in patients with pulmonary embolism remains unknown.

CASE REPORT

A 56-year-old woman presented for medical evaluation following an episode of syncope. Except for having mild arthritis, the woman said that she had been in relatively good health until the day before admission when, she reported, she had begun experiencing shortness of breath. The next morning (the day of admission), she had an episode of syncope after awakening.

The woman denied having chest pain, cough, or hemoptysis. Physical examination revealed mild respiratory distress; pulse was 104 beats/min, respiratory rate was 30/min, temperature was 36.8ˇC, and blood pressure was 115/70 mm Hg. Oxygen saturation was 93% while the patient was breathing room air. Her jugular veins were mildly distended. A loud pulmonic second sound was discernable during the cardiovascular examination, but it was not accompanied by a gallop. The rest of the physical examination was unremarkable.

On admission, laboratory studies indicated a potassium level of 2.9 mEq/L. Arterial blood gas measurements were as follows: pH was 7.47, PaO2 was 58 mm Hg, and PCO2 was 32 mm Hg. The results of the patient's creatine kinase MB isoenzyme testing were negative.

Sinus tachycardia was evident on the electrocardiogram, and a chest film showed a minimally enlarged cardiac silhoutte without congestion or infiltrate. Transthoracic echocardiography indicated a dilated right atrium and right ventricle, and a freely mobile, 2.3-cm thrombus was seen in the right atrium (Figure 1). Atrial contractility was good.

Ventilation-perfusion scans showed mismatch in the right upper lobe, right basilar segment, and left lingular segment (Figure 2 and Figure 3). Transesophageal echocardiography was not performed because the thrombus could be seen on the transthoracic echocardiogram. The patient was given a diagnosis of right atrial thrombosis with pulmonary embolism. She was admitted to the ICU and treated with intravenous heparin. She remained short of breath but was hemodynamically stable.

However, on the fourth hospital day, the patient became hemodynamically unstable. Repeat transthoracic echocardiography still showed an extremely mobile right atrial mass. The patient was treated with 100 mg of intravenous recombinant tissue plasminogen activator (r-tPA) over two hours. Twelve hours later, the patient's condition stabilized, and echocardiography showed that the thrombus had disappeared (Figure 4). A subsequent ventilation-perfusion scan showed no perfusion defect (Figure 5). On day 6, the patient was discharged to home. Oral anticoagulation was continued for six months, and the patient's condition remained stable.

DISCUSSION

Currently, two types of thrombi have been recognized. Type A thrombi, which originate in the deep peripheral veins, are extremely mobile. Type B thrombi develop within the heart chambers; they are parietal and immobile.[1] Transthoracic echocardiography is considered the best method for diagnosing right atrial thrombosis in an emergency because it allows good visualization of the right heart chambers.[2,3]

Several treatment options are available, including anticoagulation, embolectomy, and thrombolysis. The success and survival rates of each approach vary, depending on the patient's clinical status.[4] In a study by Chartier et al,[5] the mortality rate for patients with right heart thrombi and pulmonary embolism was about 45%; mortality was similar regardless of the therapeutic approach used (ie, embolectomy, thrombolysis, heparin, interventional percutaneous techniques).

Heparin: Although heparin is generally considered to be the safest treatment, its use has historically been associated with many complications, including potentially life-threatening ones, such as thrombocytopenia.[6,7]

Embolectomy: Pulmonary embolectomy and complete resection of the right heart thrombus has two drawbacks: It is not readily available in all medical centers, and it is sometimes associated with an extremely high mortality rate.

Thrombolysis: Because of the limitations of anticoagulation and embolectomy for right atrial thrombosis, thrombolysis is considered by some to be the treatment of choice. Preterm infants and newborn children with right atrial and intracardiac thrombosis have been successfully treated with thrombolytic therapy, without any complications.[8,9] Thrombolytics have also been used safely in patients with right atrial thrombosis related to central venous catheters.[10] Even in patients with heparin-induced thrombocytopenia, thrombolysis can be used to destroy the clot in the right atrium.[6,7]

Thrombolytic therapy is not without risk, however: It may cause the right atrial thrombus or its fragments to become dislodged and then to move into the pulmonary arteries.[11] Several cases of pulmonary embolism--possibly linked to thrombus fragmentation--have been reported, but there were no fatalities in patients who were hemodynamically stable at the onset of treatment.[12]

CONCLUSION

Although the most appropriate therapeutic approach for managing right heart thrombi remains to be determined, our data suggest that thrombolytic therapy with r-tPA is effective, readily available, and represents an alternative to surgery.

References
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