Asian Cardiovasc Thorac Ann 2002;10:80-82
© 2002 Asia Publishing EXchange Pte Ltd
Right Pulmonary Artery-to-Left Atrial Fistula
Ali Faizal, MD,
Nainar Madhu Sankar, MS1,
Kona Samba Murthy, MCh1,
Kotturathu Mammen Cherian, MS1
Department of Cardiology
1 Department of Cardiovascular Surgery Institute of Cardiovascular Diseases Madras Medical Mission Chennai, Tamil Nadu, India
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Ali Faizal, MD Tel: 91 44 656 5961 Fax: 91 44 656 5510 email: mmmbits{at}giasmd01.vsnl.net Department of Cardiology, Institute of Cardiovascular Diseases, Madras Medical Mission, 4A Dr. J Jayalalitha Nagar, Mogappair, Chennai, Tamil Nadu 600050, India.
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ABSTRACT
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Right pulmonary artery-to-left atrial fistula is a rare congenital anomaly. Contrast echocardiography and cardiac catheterization diagnosed a right pulmonary artery-to-left atrial fistula in a 24-year-old female with a history of cyanosis since childhood, and recurrent thromboembolism. She underwent successful surgical closure of the fistula.
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INTRODUCTION
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Direct communication between the right pulmonary artery (RPA) and the left atrium (LA) is a rare congenital anomaly.1 Such patients usually present with cyanosis, clubbing, exertional dyspnea, or uncommonly with complications of cerebral or systemic embolism.1,2 A case of RPA-to-left atrial fistula is described.
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CASE REPORT
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A 24-year-old female with a history of cyanosis from 4 years of age, presented with recurrent abdominal pain. Two months earlier, she had been hospitalized elsewhere for abdominal pain and diarrhea. Ultrasound scanning and a spiral computed tomogram of her abdomen had revealed infarction of the liver and spleen, and an abscess in the liver with ischemic bowel thickening. She had undergone laparotomy and drainage of the abscess which was sterile. She had deep cyanosis and clubbing but the cardiac examination was unremarkable. There was mild diffuse tenderness of the abdomen. An electrocardiogram revealed left atrial enlargement. Chest radiography showed increased pulmonary vascularity with left atrial enlarge-ment. An echo Doppler study showed situs solitus, normal pulmonary and systemic venous drainage, normal cardiac chambers and valves, and an ostium secundum atrial septal defect (ASD). A contrast echocardiographic study revealed immediate and dense opacification of the LA, suggesting a pulmonary arteriovenous communication. Catheterization showed mixed venous O2 saturation of 42% and severe systemic desaturation at the left atrial level. The PaO2 was 42% and SaO2 was 68%. The calculated right-to-left shunt was 0.77 L•min-1; the left-to-right shunt was 0.078 L•min-1. A pressure study was within normal limits. Pulmonary angiography (Figure 1
) revealed direct communication between the RPA and the dilated LA. Levo-phase angiography of both sides showed normal pulmonary venous drainage, confirming the diagnosis of RPA-to-left atrial communication. One week later, when the patient was waiting for surgery, she developed saddle thromboembolism of the aortic bifurcation, presenting as severe acute pain in both lower limbs. It was treated successfully by emergency thromboembolectomy. Two weeks later, the patient underwent surgery. There was a large communication between the RPA and the LA, measuring 3 cm in diameter, and a small secundum ASD. Under standard cardio-pulmonary bypass, bicaval cannulation, and fibrillatory arrest with topical ice slush, the LA was opened at the Waterston groove. The fistula was closed using a Gore-Tex patch (WL Gore, F1agstaff, AZ, USA) and continuous sutures of Prolene (Ethicon, Johnson & Johnson Ltd, Aurangabad, India). The ASD was closed via a right atriotomy. The patient was rewarmed, deaired, and weaned smoothly from cardiopulmonary bypass. Her systemic O2 saturation was > 95% immediately after surgery. She had an uneventful recovery. Pre-discharge, repeat cathe-terization showed normal systemic saturations. Pulmonary artery (PA) angiography revealed no residual communi-cation between the RPA and the LA, and no residual ASD (Figure 2). Postoperative chest radiography showed a marked reduction in the size of the LA.
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Figure 1. Preoperative pulmonary artery angiogram showing direct communication between the right pulmonary artery (RPA) and the left atrium (LA).
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Figure 2. Postoperative pulmonary artery angiogram showing complete closure of the fistula between the right pulmonary artery and the left atrium.
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DISCUSSION
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The first case of RPA-to-left atrial fistula was corrected by Blalock in 1950 and reported by Friedlich and colleagues3 in 1950. Since then, more than 50 cases of RPA-to-left atrial fistula have been reported.1,4 They can present symptomatically from infancy to late adulthood. Those who present late have a milder clinical course compared to those presenting in infancy. The usual clinical presentation is cyanosis, clubbing, and exertional dyspnea. Since the PA communicates directly with the LA, bypassing the pulmonary filter function, the patient may present with cerebral or systemic embolization or abscesses.1,2
The diagnosis should be suspected in a patient with cyanosis and a structurally normal heart. Clinical examination and routine investigations may not be contributory. Electrocardiography may reveal left atrial and ventricular enlargement, as well as cardiomegaly on a chest radiograph, depending on the hemodynamic burden. Contrast echo will definitely help to confirm a PA-to-pulmonary venous or left atrial fistula, the pathognomonic finding being early appearance of dense contrast in the LA (within 2 to 3 cardiac cycles) when contrast is injected into the arm veins. Cardiac catheterization shows left atrial desaturation not responding to inhaled oxygen, and a selective pulmonary angiogram discloses the communication by immediate opacification of the LA. According to De Souza e Silva and colleagues,5 PA-to-left atrial fistula can be classified into 3 types based on the presence or absence of an aneurysm in the fistula and the anatomy of the pulmonary venous drainage pattern. Embryologically, it has been suggested that this anomaly results from an abnormal communication between the PA and pulmonary veins, which subsequently gets incorporated into the LA.5,6 Usually, the communication is between the posterior aspect of the RPA and the superior aspect of the LA, as in this patient.
Once diagnosed, this condition should be treated by elective surgery. Although therapeutic embolization has been reported, if the fistula is large it exposes the patient to the risk of complications; hence surgery is the preferred therapeutic option.7 In the literature, approximately 50% of patients underwent ligation alone, 12% had ligation and division, 10% had excision, and 8% had intracardiac repair. Our patient underwent intracardiac repair due to the large size of the fistula and the additional presence of an ASD. Early diagnosis is essential as a delay can lead to complications and multiple surgical interventions, as in this case. Surgical correction soon after diagnosis is recommended. Surgery offers a complete cure and the patient can return to normal cardiovascular status almost immediately.
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REFERENCES
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ABSTRACT
INTRODUCTION
