Interact CardioVasc Thorac Surg 2009;8:283-286. doi:10.1510/icvts.2008.193128
© 2009 European Association of Cardio-Thoracic Surgery
Case report - Vascular thoracic |
Intraoperative retrograde type I aortic dissection in a patient with chronic type IIIb dissecting aneurysm
Satoshi Yamashiro*,
Yukio Kuniyoshi,
Katsuya Arakaki and
Hitoshi Inafuku
Thoracic and Cardiovascular Surgery Division, Department of Bioregulatory Medicine, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
Received 2 September 2008;
received in revised form 4 November 2008;
accepted 10 November 2008
*Corresponding author. Tel.: +81-98-895-1168; fax: +81-98-895-1422.
E-mail address: y3104{at}med.u-ryukyu.ac.jp (S. Yamashiro).
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Abstract
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Iatrogenic acute aortic dissection of the ascending aorta during cardiac surgery is a rare but potentially fatal complication. We describe the emergency repair of iatrogenic acute aortic dissection of the ascending aorta during distal arch replacement in a patient with a chronic type IIIb dissecting aneurysm. We scheduled distal arch and descending aortic aneurysm repair through a left anterolateral thoracotomy with a femoro-femoral bypass. While trimming the proximal suture line, retrograde aortic dissection occurred from the cross-clamped site to the aortic root. Transesophageal echocardiography revealed aortic dissection at the ascending aorta. As soon as the additional median sternotomy was established, the ascending aorta was transected and antegrade selective cerebral perfusion was applied without waiting for further cooling. Total arch replacement with descending aortic and root replacements then proceeded. The patient recovered uneventfully after extensive surgical replacement of the thoracic aorta and remains asymptomatic at two years after the procedure. To prevent possible neurological complications, this patient was managed by selective antegrade cerebral perfusion at 31 °C because we could not afford to wait for the induction of deep hypothermia. Successful management of iatrogenic acute aortic dissection depends on immediate recognition and the appropriate choice of surgical repair.
Key Words: Aortic dissection; Transesophageal echocardiography; Selective cerebral perfusion; Deep hypothermia; Circulatory arrest
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1. Introduction
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Iatrogenic acute aortic dissection (IAAD) of the ascending aorta during cardiac surgery is a rare but potentially fatal complication [1–7]. Aortic cannulation, aortic cross-clamping, partial-occlusion clamps, proximal aortic anastomosis, and retrograde dissection from femoral cannulation are responsible for most dissections [1–7]. This lethal complication arose during distal arch replacement for a patient with chronic type IIIb dissection. Prompt diagnosis and treatment can improve the survival of patients who develop this complication.
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2. Case report
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A 56-year-old man with a chronic type IIIb dissecting aneurysm was referred to our institution for distal arch replacement. He had no history of diabetes, hypertension, hyperlipidemia or smoking, and male gender was the sole identified classical risk factor. He was followed up with serial imaging at least annually and surgery was recommended at three years after the initial dissection because the absolute maximal diameter of the aorta exceeded 6.0 cm. Aortography showed an entry site at immediately distal to the left subclavian artery. An intimal flap reached from the distal arch to the terminal aorta. The descending aorta was dilated to 4.0 cm, but returned to a more normal diameter of 3.0 cm at the level of the diaphragmatic hiatus. Distal arch and descending aortic aneurysm repair through a left thoracotomy was thus indicated (Fig. 1).
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Fig. 1. (a) Preoperative 3D-CT shows aneurysmal dilation from distal arch to descending aorta due to chronic type IIIb dissecting aneurysm (arrow). (b) Intraoperative findings show significantly enlarged distal arch (arrow).
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The patient was positioned supine on an operating table with the chest rotated 60° towards the right. A left anterolateral thoracotomy proceeded at the 4th intercostal muscle. Cardiopulmonary bypass (CPB) was established with the arterial cannula placed in the right femoral artery and a venous cannula placed for drainage in the right femoral vein. Usually, we performed proximal first for distal arch or descending aortic replacement. However, we had planned distal first because proximal procedure has been predicted to confuse in this case to avoid hypothermic circulatory arrest (HCA) with selective cerebral perfusion (SCP). The descending aorta was clamped at the level of the 6th vertebra which was the predicted site of the distal anastomosis, and transected. The intimal flap was fenestrated and then distal anastomosis was performed with cross-clamping under distal perfusion. Proximal anastomosis immediately distal to the left subclavian artery was planned under cross-clamping of the arch aorta between the left common carotid artery and the left subclavian artery. While trimming the proximal suture line, retrograde aortic dissection occurred from the cross-clamping site to the aortic root (Fig. 2). At first, we found it visually as intramural hematoma. The ascending aorta in progress to enlarge and a massive hemorrhage occurred around the right coronary ostia. Transesophageal echocardiography (TEE) revealed aortic dissection at the ascending aorta with severe aortic valve regurgitation.
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Fig. 2. Intraoperative findings.
Retrograde aortic dissection (arrow) from cross-clamping site to aortic root (a,b,c).
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Core cooling was started and a median sternotomy was immediately added to provide a good visual field. As soon as the combined approach was established, the ascending aorta was transected and antegrade SCP was administered without waiting for further cooling. The temperature of antegrade SCP was maintained at 15 °C, and cerebral perfusion was established at a flow rate of 10–15 ml/kg/min, using a double roller pump separate from the systemic circulation. Radial artery and left carotid artery stump pressure were monitored, which was controlled between 40 and 50 mmHg by regulating SCP flow. Per-operative blood flow through the middle cerebral arteries was monitored continuously with bilateral transcranial Doppler (Viasys Inc. Conshocken, PA, USA). Moreover, cerebral oxygen saturation was monitored with the Somanetics Invos® Cerebral Oximeter (CO, Troy, MI, USA). Retrograde systemic circulation was continued from the right femoral artery. The temperature of distal perfusion from femoral artery was maintained at 20 °C. The myocardium was protected by intermittent antegrade and retrograde cold-blood cardioplegia. Arch vessels were anastomosed to their respective limbs of the graft succession. Antegrade SCP was terminated after reconstruction of the arch vessels, and then antegrade perfusion from graft limb was started. Thereafter, the distal part of the arch graft was anastomosed to the descending aortic graft that had been originally reconstructed. Because dissection had been extended to Valsalva (especially in right coronary sinus) and severe aortic valve regurgitation had been recognized by TEE. Moreover, the right coronary ostium was perforated. We decided to reconstruct the aortic root using a modified Bentall procedure with Carbo-seal® (Carbomedics, Austin, TX, USA). The left coronary artery was reconstructed using a carrel patch. The right coronary artery was revascularized with a saphenous vein graft. Total CPB time, cardiac ischemic time and SCP time were 405, 346 and 108 min, respectively. Initial operation was finished with only skin closure to obtain complete hematemesis by packing, and myocardial edema was observed due to elongated CPB time and cardiac ischemic time. The replaced graft was covered with a pedicled omental flap to prevent postoperative graft infection, after packing with sponges soaked in 10% iodine solution for 48 h afterwards. Fortunately, the patient's postoperative course was uneventful without neurological complications. Mechanical ventilation was required after second surgery for three days. No new phrenic or left recurrent laryngeal nerve palsies occurred as a result of surgery. The length of the hospital stay after surgery was 35 days and he remains asymptomatic at two years after the procedure.
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3. Discussion
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Hypothermic circulatory arrest (HCA) with or without SCP has become the standard approach for surgery of the aortic arch [8, 9]. However, hypothermia is often associated with a bleeding tendency, respiratory disorders and immunodeficiency [8]. Moreover, brain damage can occur due to cannulation for arch vessels [9]. We believe that HCA with SCP should be avoided if possible. Usually we performed descending aortic aneurysm repair through a left antero-lateral-posterior thoracotomy. However, we suspected a total arch replacement would be required. If so, we would use a combined approach (median sternotomy with left anterolateral thoracotomy). However, the aortic arch in this patient including arch vessels were easily exposed and seemed normal. Epiaortic echography revealed no atheromatous changes and no calcification in the arch aorta. Therefore, we decided to perform a proximal procedure under cross-clamping of arch aorta between the left common carotid and left subclavian arteries. However, retrograde dissection occurred from the aortic cross-clamping site. IAAD is a potentially fatal complication of cardiac surgery [1–7] with an estimated prevalence of 0.16%–0.35% [1, 2]. This complication can originate anywhere including sites of aortic cannulation, aortic cross-clamping, partial lateral clamping, cardioplegia, venous anastomosis, aortotomy, or retrograde dissection of the ascending aorta associated with femoral artery cannulation [1–7].
If cerebral malperfusion is suspected in a patient with IAAD, waiting for deep HCA could lead to irreversible brain damage [5]. Neurological injury remains the single most important source of morbidity and mortality in thoracic aortic surgery [1–3, 5]. Therefore, to open the aorta rapidly and apply SCP without waiting for hypothermia is preferable in such cases. Moreover, organ ischemia must be avoided in IAAD. Murphy et al. [1] attributed their 33% mortality rate to subsequent myocardial dysfunction due to prolonged cross-clamping time. We usually perform total arch replacement through a median sternotomy with left anterolateral thoracotomy when an extended thoracic aortic aneurysm involves atherosclerotic aneurysms or chronic type A or B dissection. The ability to visualize and protect the phrenic and recurrent laryngeal nerves contributes to accelerate recovery in patients with impaired respiratory function. The myocardium can also be appropriately protected by applying this approach.
We had prepared an SCP circuit and cardioplegia for HCA to the proximal procedure, which allowed us to open the aorta very quickly and apply antegrade SCP and the cardioplegic solution, which rescued this patient. Notably, slipshod manipulation of the aorta can cause intraoperative iatrogenic lethal complications in patients with chronic dissection, even when epiaortic echography seems to show a normal aortic wall and intima. Successful management of IAAD depends on immediate recognition and appropriate surgical repair as the mortality rate is approximately 20% after recognition and management in the operating room [1, 2, 5]. Prompt recognition of IAAD and appropriate repair are essential for a successful surgical outcome. Antegrade SCP was applied immediately to provide cerebral perfusion and hypothermia in our patient, although the systemic temperature remained somewhat higher than we would have preferred. We believe that this approach provides safer and more controlled cerebral perfusion.
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References
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Abstract
1. Introduction