Acute Aortic Dissection with an Aorta–Right Atrium Fistula

Abstract

We describe a rare complication of an acute aortic dissection. Proximally the dissection propagated into the right atrium, resulting in an aorta–right atrium fistula. The clinical course, operative findings, and operative treatment are discussed. (Tex Heart Inst J 2003;30:335–6)

Acute aortic dissections frequently propagate proximally to the aortic root. It is not uncommon for the patient to develop subsequent aortic valve insufficiency, coronary insufficiency, or cardiac tamponade. We describe an aortic dissection that originated in a tear of the ascending aorta and propagated proximally into the aortic root. In addition to generating aortic insufficiency, the dissection spread into the right atrium, resulting in an aorta–right atrium fistula.

Case Report

In August 2000, a 57-year-old woman presented 14 hours after the sudden onset of severe back pain. She had a history of severe hypertension. On physical exam, her blood pressure was 160/80 mmHg, and she had a murmur consistent with aortic insufficiency. She had severe bilateral rales, and chest radiography revealed a wide mediastinum and severe pulmonary congestion. Computed tomography revealed an aortic dissection from the aortic valve down to the diaphragm.

Upon the patient's entry into the operating room, her systolic blood pressure had fallen to 100 mmHg. Her pulmonary artery pressure was 65/35 mmHg, and her central venous pressure was 35 mmHg. Her mixed venous oxygen saturation was over 80% despite overt clinical congestive heart failure. Transesophageal echocardiography was not initially available. Upon opening the pericardium, we saw no pericardial fluid or tamponade of note. The systemic hypotension, pulmonary hypertension, and venous hypertension persisted. The right atrium was very distended, pulsatile, and red. The patient was connected to right atrium–femoral artery bypass and cooled to 16°C. The circulation was arrested and the ascending aorta was opened. The entry tear in the ascending aorta was found and resected. A 28-mm ascending aortic interposition graft was placed, with use of a Teflon reinforced distal suture line, and an arterial cannula was moved into the graft. The aorta was de-aired, the graft was cross-clamped, and the circulation was restarted after 28 minutes. Next, the aortic valve was resuspended. An aorta–right atrium fistula consisting of a false lumen along the noncoronary cusp was identified (Fig. 1). Closure of the fistula was incorporated into the reinforcement of the native ascending aorta. Just above the aortic valve leaflets, an inner and outer circumferential rim of Teflon was used to sandwich the aortic layers between the Teflon. In addition, the right atrium was opened, and a Teflon patch was placed over the entry point of the fistula. This atrial patch was used to reinforce the atrial tissue that closed the fistula and was then sewn into the aortic Teflon sandwich. As the Teflon was sewn together, the fistula was closed and the false lumen obliterated. Subsequently, the aortic graft was sewn to the Teflon-reinforced ascending aorta, and the aorta was de-aired.

Fig. 1 Drawing shows the ascending aortic dissection with an aorta–right atrium fistula. (Illustration by Rachid Farouk Idriss.)

After cardiopulmonary bypass, the systemic blood pressure averaged 120/80 mmHg, the pulmonary artery pressures averaged 20/10 mmHg, and the central venous pressure averaged 10 mmHg. Intraoperative transesophageal echocardiography revealed trivial aortic insufficiency and no residual fistula. Postoperatively, the patient had no complications and was discharged from the hospital 5 days after the operation. Three years later, the patient was doing well.

Comment

This case demonstrates the close anatomic relation ship between the aortic root and the right atrium. Anatomically, the right atrium abuts the aorta along the noncoronary and right coronary cusps. Fistulas to the right atrium can occur in patients who have a congenital aneurysm of the sinus of Valsalva. Most such aneurysms eventually rupture into an adjacent cardiac chamber. When the aneurysm originates in the noncoronary cusp, the fistula leads into the right atrium in 70% of cases. ¹ To our knowledge, this is the 1st report in the English-language medical literature of an acute aorta–right atrium fistula resulting from an acute aortic dissection. Our case emphasizes the importance of surgically treating patients with Type A aortic dissections as emergent cases as soon as possible after the diagnosis is made. Awareness of the rare possibility of an aorta–right atrium fistula might be useful in the management of Type A aortic dissections.