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MMCTS
(January 2, 2007). doi:10.1510/mmcts.2006.001974 Copyright © 2007 European Association for Cardio-thoracic Surgery
Procedure Arch first technique under deep hypothermic circulatory arrest with retrograde cerebral perfusionDepartment of Surgery, Division of Cardiac Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan * Corresponding author: * Tel.: +81-52-744-2376; fax: +81-52-744-2383 E-mail: ausui{at}med.nagoya-u.ac.jp
We have adopted the arch first technique with four-branched graft for total arch replacement since 1998 to reduce the period of deep hypothermic circulatory arrest and the retrograde cerebral perfusion time. This procedure was performed in 85 cases (58 males and 27 females), with an average age of 68 years. There were 61 true aneurysms, 21 aortic dissections and 3 others. Stroke was a complication in 6 cases (7%). Other morbidities were re-exploration for bleeding in 9, low output syndrome in 2, and renal dysfunction in 3. There were 3 hospital deaths (3.5%), 4 late deaths. The five-year survival rate was 89.1%. The arch first technique results in low surgical mortality and morbidity and provides a higher survival rate. The arch first technique is an excellent method for total arch replacement.
Key Words: Aortic arch • Survival analysis • Retrograde perfusion • Quality of life • Cerebral protection
Total arch replacement requires cerebral protection. We have applied deep hypothermic circulatory arrest with retrograde cerebral perfusion (RCP) to reconstruct the arch and arch vessels with a four-branched graft. RCP provides a better operative field without complicated cardiopulmonary circuits, but there are time limitations on safe interval. The safe interval of RCP is reported to be <60 min [1,2,3], however, a shorter period of circulatory arrest should provide better brain protection and faster neurological recovery after surgery. We have adopted the arch first technique instead of the conventional distal anastomosis first technique since 1998 to reduce the period of circulatory arrest with RCP. We introduce our surgical technique and show the clinical outcome of our experiences. It should clarify the advantages of our technique.
Anesthesia Mitazolam (0.05 mg/kg) is given intramuscularly as a premedication. Anesthesia is induced by means of an intravenous injection of Mitazolam (0.1 mg/kg), Fentanyl citrate (10 µg/kg) and Vecuronium bromide (0.1 mg/kg), and is maintained with Fentanyl citrate (1–4 µg/kg/h) and Vecuronium bromide (2 mg/h) until the end of surgery, with or without Sevoflurane inhalation. Mechanical ventilation is maintained with a single lumen endotracheal tube. A double lumen endotracheal tube or bronchial blocker is used when left thoracotomy is required.
Approach Cardiopulmonary bypass Cardiopulmonary bypass is applied with bicaval drainage and the ascending aorta perfusion after careful inspection with direct epiaortic echocardiography (Video 2). The diseased aorta is avoided for a cannulation site, and a dispersion type cannula (Edwards Lifesciences – MMCTSLink 134) is used to avoid sandblast phenomenon. The right axillary artery is chosen only when the ascending aorta has severe arteriosclerosis. For the superior vena cava (SVC) drainage, a single venous cannula (Toyobo INKC-S2, Osaka, Japan) is placed in the SVC via the right atrium or a metal tip venous cannula (Pacifico DLP693, Medtronic – MMCTSLink 123) is inserted directly into the SVC. An umbilical tape is applied only around the SVC. Systemic core cooling is applied under venting the left ventricle via the right upper pulmonary vein (Schematic 1).
Barbital sodium (500 mg) and 20% mannitol (150 ml) are administered when the nasopharyngeal temperature falls to 22°C. Perfusion is discontinued once the nasopharyngeal temperature falls below 20°C. An anesthetic-depth monitor (BIS A-1050, Aspect Medical Systems Inc. – MMCTSLink 135), which is essentially a simplified EEG, is useful to monitor brain activity. After this monitor shows a nearly flat level of EEG activity, circulatory arrest should be established. The drainage circuit is clamped to avoid excess blood removal first, and the blood pump is stopped.
Aortic arch reconstruction
Retrograde cerebral perfusion and antegrade cerebral perfusion via the graft RCP is applied via the superior vena cava (SVC) cannula snared with an umbilical tape under clamping the inferior vena cava cannula and aortic perfusion cannula. SVC pressure is maintained at approximately 10–15 mmHg, with 250–350 ml/min flow rate. Effluent blood flow via the aorta is sucked. Blood temperature is kept at approximately 16–18°C. A pH-stat blood-acid management is applied by supplying with 1.5 l/min oxygen and 0.1 l/min carbon dioxide to the oxygenator while nasopharyngeal temperature is kept under 25°C. RCP is usually initiated after reconstructing the left subclavian artery. After anastomosis of the arch vessels, the flow rate of RCP is once more increased to 1000 ml/min to complete deairing and to flush debris from the aortic arch for 1 min; the RCP is then stopped, and antegrade cerebral perfusion is resumed (Schematic 3, Video 7).
Cardioplegia Cold blood cardioplegia is given after initiation of circulatory arrest. Cross clamping is applied to the ascending aorta just distal of the perfusion cannula, and cardioplegia is given via its cannula. Additional cardioplegia is given every 30 min. Selective coronary perfusion of cardioplegia is also used for the diseased ascending aorta.
Distal anastomosis
Graft-to-graft anastomosis The distal graft and arch graft are anastomosed with a 3-0 or 4-0 polypropylene running suture (Schematic 5, Video 9).
Proximal anastomosis Proximal anastomosis between the arch graft and aortic root is completed (Schematic 6, Video 10). An extensive aortic arch replacement can be done through an upper sternotomy with anterior left thoracotomy.
Weaning from cardiopulmonary bypass Core rewarming is carried on until it reaches a nasopharyngeal temperature of 35–36°C and bladder temperature of 33–34°C. Over-rewarming is avoided to maintain the blood temperature under 37°C. After weaning off cardiopulmonary bypass, heparin is neutralized with protamine sulfate.
Patients The arch first technique has been performed in patients with arch or distal arch aneurysm involving the left subclavian artery. Aneurysms not extending to the mid-descending aorta have been exposed through median sternotomy. Aortic arch aneurysm involving the mid-descending aorta has been replaced through upper partial median sternotomy with anterior left thoracotomy via the 4th or 5th intercostal space. From 1998 to 2005, 85 consecutive cases underwent the arch first technique. They were 58 males and 27 females with an average age of 68 years, ranging from 35 to 82 years. There were 61 true aneurysms involving 3 rupture cases, 12 chronic and 9 acute Stanford type A dissections, 2 penetrating aortic ulcers and 1 aortic sarcoma. An emergency operation was performed in 12 cases. Four cases were redo surgery. Seventy-six cases were performed via median sternotomy and nine others were done via upper partial sternotomy with left anterior thoracotomy. Concomitant procedures were aorto-coronary bypass grafting in 12, aortic root reconstruction in 7, aortic valve replacement in 4, and mitral valve repair in 2 (Table 1).
Clinical outcomes The mean operation time was approximately 7 h. The mean cardiopulmonary bypass time exceeded 3.5 h as a result of using deep hypothermia, with an average lowest esophageal temperature of 19.2°C. The mean circulatory arrest time with retrograde cerebral perfusion was 30 min, ranging from 19 to 52 min. However, the lower body ischemic time was 74 min for distal anastomosis. The cardiac ischemic time was 123 min (Table 2).
Sixty-one patients awoke within 8 h after surgery, with an average delay of 8.8 h. Fifty patients were extubated within 48 h, though the average intubated period was 51 h. Fifty-one patients were discharged from the ICU within 3 days. No blood transfusion was required in 13 cases. Strokes complicated surgery in six cases (7%) and six other cases revealed reversible ischemic neurological deficit (RIND). Another two cases suffered stroke postoperatively. Temporary psychiatric disorder, such as delirium, was observed in a further six cases (7%). Other morbidities included re-exploration for bleeding in nine, low output syndrome in two, and renal dysfunction in three (Table 2). There were three hospital deaths (3.5%). One patient died as a result of residual descending aortic aneurysm rupture three weeks after surgery. Another died of a stroke one month after surgery and one patient with Bechet disease died after five repeated operations for bronchial fistula and graft infection 6 months after the initial surgery. All patients, except hospital deaths, were discharged without nursing care after an average hospital stay of 49 days. There were four late deaths, as a result of stroke in three patients and pneumonia in one. The five-year survival rate was 89.1%, with an average follow-up period of 34 months. Eighty-three percent of patients had no social disability, but there was slight social disability in six and severe social disability in four.
RCP was reported as a technique for brain protection for aortic surgery by Lemole et al. in 1982 [5], and by Ueda et al. in 1990 [6], and has become generally accepted as an adjunct for deep hypothermic circulatory arrest. Experimental studies showed that RCP supplies some amount of oxygen to the brain and serves to maintain brain cooling [7, 8] and minimize ischemic brain damage. RCP can be performed without any aortic clamp or additional cannulation, also it flushes away air or debris from the cerebral arteries, and helps to avoid cerebral embolization. RCP may therefore be a useful adjunct procedure in cases of hypothermic circulatory arrest because it can extend the period of time during which cerebral circulation can be safely interrupted. Since RCP still has the drawback of limited safe duration [9, 10], we have proposed that it should not exceed 60 min because it is non-physiological perfusion [1,2,3]. We believe that a shorter period of circulatory arrest is better for cerebral protection and neurological recovery after surgery [11]. Thus, we have applied the arch first technique since 1998 with the aim of shortening the duration of interruption of cerebral perfusion and to resume antegrade cerebral perfusion more reliably than by selective cerebral perfusion. Our clinical outcomes demonstrated that the arch first technique provided better neurological outcomes and also led to an obvious reduction in hospital mortality and a clear improvement of the early morbidity and subsequent quality of life as well. We believe that this is due to the shorter circulatory arrest period and further surgical refinements. Surgical results for total arch replacement have recently been improving, and several reports now show <5% surgical mortality [12,13,14]. This success shifts the goal from reducing surgical mortality and morbidity to improving the quality of life after surgery. Our clinical outcomes bear comparison with these reports and have attained better quality of life after surgery.
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Summary
Introduction
