Ann Thorac Surg 2009;88:1670-1671. doi:10.1016/j.athoracsur.2009.04.063
© 2009 The Society of Thoracic Surgeons
Case Reports
Acute Thrombosis of Abdominal Aortic Aneurysm During Cardiac Surgery
Fadia Haddad, MDa,*,
Alexandre Yazigi, MDa,
Issam El-Rassi, MDb,
Samia Madi-Jebara, MDa,
Khalil Jabbour, MDa,
Victor Jebara, MDb,
Naji Al Ayle, MDb
a Department of Anesthesiology and Intensive Care, Hotel Dieu de France Hospital, Alfred Naccache Street, Beirut, Lebanon
b Department of Cardiovascular Surgery, Hotel Dieu de France Hospital, Alfred Naccache Street, Beirut, Lebanon
Accepted for publication April 13, 2009.
* Address correspondence to Dr Haddad, Department of Anesthesiology and Intensive Care, Hotel-Dieu de France Hospital, Saint Joseph University, Alfred Naccache St, PO Box 166830, Beirut, Lebanon (Email: fflhlb{at}yahoo.com).
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Abstract
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Aortic thrombosis has been described in the medical literature as a rare and catastrophic complication of abdominal aortic aneurysms. However, it has only been reported once in cardiac surgical settings. We report a unique case of thrombosis of an abdominal aortic aneurysms during the course of cardiac surgery, in a fully anticoagulated patient on cardiopulmonary bypass. Prompt diagnosis and immediate surgical management were critical for a successful outcome.
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Introduction
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Acute thrombosis of an abdominal aortic aneurysm (AAA) is a rare but serious complication associated with high mortality [1, 2]. Most cases have been reported in medical settings, with numerous and debatable predisposing factors [1, 3, 4]. We hereby report a unique case of thrombosis of an AAA in a fully anticoagulated patient on cardiopulmonary bypass (CPB) for cardiac surgery.
A 70-year-old Caucasian woman was scheduled for replacement of the ascending aorta for an ascending aortic aneurysm. She was a heavy smoker, hypertensive, and diabetic. She had survived an acute type A aortic dissection 2 years prior without surgery. Preoperative multi-detector computerized tomography showed a large ascending aorta measuring 65 mm, with a localized dissection originating 1 cm above the sinotubular junction, extending to the origin of the innominate artery. The aortic root and arch were normal. The descending thoracic and abdominal suprarenal aorta was also normal. The multi-detector computerized tomography revealed an infrarenal 55-mm abdominal aortic aneurysm lined with thrombus, but with a patent lumen. The coronaries were normal on the multi-detector computerized tomography, and the coronary artery angiography was not performed. The echocardiogram showed a normal aortic valve and good left ventricular function with an ejection fraction of 66%.
In preparation for surgery, a left radial and a left femoral arterial catheters were placed, as well as a Swan-Ganz catheter for hemodynamic monitoring. Cardiopulmonary bypass was instituted between the right axillary artery and the right atrium. Myocardial protection was accomplished by intermittent anterograde and retrograde cold blood cardioplegia. The aortic dissection was strictly limited to the ascending aorta, which was replaced by a 38-mm collagen-coated Dacron tube under moderate hypothermia without circulatory arrest. Perfusion pressure, nonpulsatile flow rate, urine output, acid-base status, and mixed venous oxygen saturation were all within normal limits all through surgery, and the activated clotting time was maintained above 450 seconds using unfractionated heparin (300 IU/kg). Aortic cross-clamping time was 113 minutes and CPB time was 156 minutes. Before and during CPB, femoral and radial artery pressures were approximately similar. In the last 30 minutes of CPB, the femoral arterial pressure was progressively decreasing compared with the radial pressure, despite repeated flushing of the catheters. Just after weaning from CPB, the systolic radial pressure was 100 mm Hg, whereas systolic femoral pressure was only 20 mm Hg, and both femoral pulses were not palpable by the surgeon. After the confirmation of the radial arterial pressure by a catheter placed in the ascending aorta, an acute thrombosis of the AAA was suspected and immediately confirmed by abdominal Doppler ultrasound. A median laparotomy was performed while the patient was off cardiopulmonary bypass but was still anticoagulated with heparin. The abdominal aortic aneurysm was found to be full of old and fresh thrombotic material and atheromatous debris, whereas the aortic bifurcation and the iliac arteries were patent. The infrarenal aorta was replaced by a 30-mm collagen-coated Dacron tube (Vascutek Ltd, Renfrewshire, Scotland). Cross clamping and unclamping of the aorta were well tolerated, and both lower limbs were adequately perfused at the end of surgery, with a left femoral arterial pressure identical to the radial. The total operative time extended to 6 hours. The patient required mechanical ventilation for 72 hours, with stable hemodynamics and no inotropes or vasopressors. She did not present any major complication. She was discharged from the cardiac surgery unit on postoperative day 5, and she was discharged home 1 week later after an uneventful hospital stay.
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Comment
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Thrombosis of an abdominal aortic aneurysm is rare [1]. It is usually as catastrophic as its rupture, and the stormy clinical setting following this sudden event is fatal in half of the cases [2]. Several factors have been incriminated in the thrombosis of the 49 reported cases; these factors include surgical manipulation, trauma, thromboembolic disease, various hypercoagulability states, hypotension, intraplaque hemorrhage, iliac artery occlusive disease, aneurysm rupture, and dislodgment of a mural thrombus within the aneurysm [1, 3, 4].
Abdominal aortic aneurysm thrombosis during cardiac surgery merits special attention; it is not associated with the usual clinical signs and symptoms suggesting the diagnosis, and the precipitating factors may be different from the ones reported in the literature. Moreover, both surgeons and anesthesiologists are usually fully aware of the existence of the aneurysm and its potential complications, and the patient is in an ideal situation for emergency repair. Combined cardiac surgery and AAA repair, with or without CPB, has been proposed to avoid this complication in high-risk patients with large aneurysms [5–7]. However, this is recommended mainly in symptomatic AAA to prevent the risk of rupture [6]; thrombosis of an AAA during cardiac surgery has never been a real concern for the cardiac surgeon, and this event has been reported only once in the medical literature [8], which occurred in the course of coronary artery surgery on a beating heart without cardiopulmonary bypass. In the author's opinion, the AAA thrombosis was related to a low-flow state with only partial heparinization during myocardial revascularization in that case. Also, in their case, hypothermia, disseminated intravascular coagulopathy with massive bleeding, and metabolic changes developed in their patient, which had a fatal outcome.
We believe that the patient we report herein is the first case of abdominal aortic aneurysm thrombosis in a fully heparinized patient on cardiopulmonary bypass. Several factors may have caused this thrombosis, including a nonpulsatile flow with a relative low blood pressure on cardiopulmonary bypass, an intraplaque hemorrhage, or a thrombus and debris dislodged by manipulation from the cardiac chambers, the aorta, or the aneurysm itself. These are only proposed mechanisms and are probably interrelated. The preoperative screening did not reveal any clots, thrombus, vegetations, or calcifications in the heart or the thoracic aorta that might have embolized. Moreover, full heparinization can not be considered protective against this complication, as heparin is not effective on clots or debris. The initial disease being aortic dissection in this patient, further dissection with flap occlusion of the abdominal aorta may be suggested as an additional cause of thrombosis; however, the dissection involved only the ascending aorta, and the walls of the abdominal aorta were not found to be dissected during repair.
In conclusion, thrombosis of an abdominal aortic aneurysm is a rare but catastrophic complication that may occur during cardiac surgery with or without CPB. The routine use of both radial and femoral arterial pressure monitoring in all patients with thoracic or abdominal aortic disease undergoing open heart procedures is critical, as it allowed for the rapid detection and emergent treatment of this dreadful complication.
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References
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- Benetis R, Putelis R, Jakutis A, Inèi°ra D. Simultaneous myocardial revascularization and abdominal aortic aneurysm repair (report of a fatal case) Medicina 2002;38:58-62.
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Abstract
Introduction
