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In a patient with degenerative disease of the thoracic aorta, an aortopulmonary fistula with an aortic aneurysm after trauma is a rare occurrence. Few cases of successful surgical management have been reported. Aortopulmonary fistula should be suspected in a patient who has an aortic aneurysm and exhibits signs of congestive heart failure. Herein, we report the case of a 50-year-old man who underwent surgical repair of an ascending aortic aneurysm with fistula into the main pulmonary artery. Early diagnosis and prompt surgical intervention were crucial to the successful outcome.
The natural course of thoracic aortic aneurysms usually involves acute aortic dissection or free rupture of the aneurysm rather than congestive heart failure. An aortic aneurysm with aortopulmonary fistula after trauma is unusual. Few cases of successful surgical management have been reported. Aortopulmonary fistula should be suspected in a patient who has an aortic aneurysm and shows signs of congestive cardiac failure. Early diagnosis and prompt surgical intervention are crucial to a successful outcome. Here, we report the case of a 50-year-old man with this combination of conditions.
In November 2007, a 50-year-old man presented at our hospital with a 1-month history of dyspnea. He had fallen from a bicycle 2 months before, striking his chest on the bicycle handles but incurring no overt trauma, and he sought no medical attention. Soon thereafter, he involuntarily inhaled concentrated fumes in a chili-powder factory, and he coughed and sneezed violently for 10 minutes until he left the premises. Since then, he had experienced chest discomfort upon exertion. The symptoms worsened over a month's time, and a physician whom he visited referred him to our institution.
The patient had no history of prolonged fever or infection. Upon examination, he was of average build and was well nourished. His blood pressure was 100/50 mmHg, with bounding pulses. The precordium was prominent, and a palpable thrill was audible in the 2nd left intercostal space. The 1st heart sound was normal, and the pulmonary component of the 2nd heart sound was loud. A grade 4/6 continuous murmur was best heard in the 2nd left intercostal space. Chest radiography revealed a widened mediastinum with pulmonary plethora. Echocardiography showed dilation of the ascending aorta (maximum diameter, 5.8 cm). Increased flow in the pulmonary artery (PA) suggested an aortopulmonary communication. There was no aortic regurgitation. An aortogram (Fig. 1) showed dilation of the ascending aorta, with a large fistulous communication between the ascending aorta and the main PA. On coronary angiography, the aortic arch and descending aorta were normal. Right-heart catheterization revealed PA pressure that was nearly equal to the aortic pressure: PA pressure, 104/50 mmHg (mean, 68 mmHg); aortic pressure, 107/55 mmHg (mean, 73 mmHg). There was a 20% step-up in oxygen saturation from the superior vena cava to the PA (69.97% to 90%). The QP/QS was 3.18, the pulmonary vascular resistance was 4.34, and the pulmonary vascular resistance index was 4.66 Wood units. In accordance with these findings, the patient was taken to surgery.
After a median sternotomy was performed, the femoral artery was cannulated with use of a 21F Bio-Medicus® cannula (Medtronic, Inc.; Minneapolis, Minn), and the right atrium was cannulated with a 2-stage single-venous cannula. A vent that was placed in the PA showed bright blood. After the initiation of cardiopulmonary bypass (CPB), the right and left PAs were looped, and ligatures were applied. Inserting the PA vent and securing it in the main branch prevented flooding of the lungs. The patient was cooled to a rectal temperature of 28 °C. The aorta was cross-clamped just below the brachiocephalic artery. A vertical aortotomy was made over the ascending aortic aneurysm, and cold-blood cardioplegic solution was administered through the coronary ostium. The ligatures around the PAs were released, and suction kept the operative field clear. Within the aorta was a large aneurysm that began above the sinotubular junction and extended to just below the origin of the brachiocephalic artery. Although no dissection flap was seen, the aortic wall was thin and, in places, the intima was disrupted. A fistulous tract approximately 2 cm in diameter and with smooth margins ran from the aorta about 2 cm above the sinotubular junction to the main PA. The fistulous tract was in the aneurysmal segment of the aorta, and mild bluish discoloration below the intima indicated old hemorrhagic regions that were perhaps due to trauma. The aortic valve was normal. No evidence of infection or vegetation was apparent inside the aorta, but a few organized hemorrhagic patches were visible near the fistula.
We decided to replace the ascending aorta from above the sinotubular junction to the distal ascending aorta with a 26-mm Hemashield® graft (Boston Scientific Corporation; Natick, Mass) and 4-0 continuous Prolene suture. The main PA was opened. The fistulous communication in the anteromedial aspect of the PA was approximately 1.5 cm in size. The edges were smooth, and there was no evidence of infection. The openings of the right and left PAs were normal. The fistulous opening was closed with use of a Dacron patch and 5-0 continuous Prolene suture. The Hemashield graft was then covered with the redundant aneurysmal wall. After de-airing, the cross-clamp was released, and the patient was weaned from CPB with minimal support.
The patient's postoperative recovery was uneventful. Echocardiography showed no communication between the neo-aorta and the PA. Upon 1-year follow-up, an echocardiogram showed no aortic regurgitation and an aortic valve systolic gradient of 23 mmHg. No shunt was seen between the aorta and the PA, and the PA pressure was normal.
Histologic examination of the excised fistula showed disruption and thinning of the media, old hemorrhagic patches, and no infection.
Aortopulmonary fistula secondary to thoracic aortic aneurysm is a rare occurrence. In 1924, in a postmortem study, Boyd1 reported a 4% occurrence of aortopulmonary fistula in 4,000 cases of aneurysms of the thoracic aorta. This type of fistula is difficult to diagnose, and there are few reports of surgical repair.2–6 Its pathologic cause could be a dissection process7 that leads to a secondary fistula into the main PA. Aortopulmonary fistula is also associated with trauma or septic processes in aortic degenerative disease. Such fistulas have also occurred after aortic surgery.8,9
The hemodynamic consequences of a large aortopulmonary fistula can rapidly lead to cardiac decompensation. Because a thoracic aortic aneurysm usually results in acute aortic dissection or free rupture of the aneurysm, a fistula should be suspected in a patient who has an aortic aneurysm and shows signs of congestive heart failure. Transthoracic echocardiography is a useful diagnostic method. High oxygen saturation in the PA blood and an oxygen step-up between the right atrium and the PA, as determined during cardiac catheterization, are confirmatory.
The 1st successful case of surgical repair was reported by Giacobine and Cooley2 in 1960. There have since been a few reports2–6 of successful surgical repair of thoracic aortic aneurysms that ruptured into the PA. The surgery consists of closing the fistula and replacing the ascending aorta with a prosthetic graft, with the patient on CPB with hypothermia (if it is possible to clamp the distal aorta). If the aortic arch is involved, the procedure entails closure and replacement with use of total circulatory arrest.
A modified approach involving interventional radiology and surgery has been reported.9 A balloon catheter was placed in the right PA to enable occlusion of the fistula during CPB, followed by repair with the use of CPB and circulatory arrest. Endovascular repair of an aortopulmonary fistula has also been reported10 in a patient who had undergone 2 thoracotomies. The fistula occurred at the site of a pseudoaneurysm from the proximal anastomosis of a graft that had been placed to treat a type B aortic dissection.
The outcome after surgery often depends on the general condition of the patient. Early reports described a high mortality rate. Since diagnostic methods have improved, more recent reports have described favorable outcomes, with prompt hemodynamic and symptomatic relief.9,10
Our patient had aortic degenerative disease, and he sustained mild trauma at around the same time that he experienced violent coughing and sneezing. These events may have led to local disruption and the formation of an aortopulmonary fistula, which gradually enlarged so that his dyspnea became prominent. The fistula in our patient may have been secondary to local rupture in an already degeneratively diseased aorta, given the numerous small areas of disrupted intima inside the aneurysmal aorta. We inferred that infection was not the cause, because no evidence thereof was present upon histologic examination of the fistulous tract with the aorta. There were, however, old hemorrhagic patches with disruption and thinning of the media.
Aortopulmonary communication should be suspected in a patient who has a dilated aneurysm of the ascending aorta, a history of infection or trauma, and generally deteriorating cardiac status. In the case of our patient, prompt diagnosis and surgical treatment led to a successful outcome.
We acknowledge the support of our cardiology and anesthesiology colleagues in the management of this patient.
Address for reprints: Mahadev D. Dixit, DNB, Director, KLES Heart Foundation, KLES Dr. Prabhakar Kore Hospital & MRC, Nehru Nagar, Belgaum, Karnataka 590010, India E-mail: moc.liamg@tixiddmrd