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Transcranial Doppler Sonography for Optimization of Cerebral Perfusion in Aortic Arch Operation

2015; Elsevier BV; Volume: 101; Issue: 1 Linguagem: Inglês

10.1016/j.athoracsur.2015.06.055

1552-6259

Tamer Ghazy, Ayham Darwisch, Torsten Schmidt, Zuzana Fajfrova, Claudia Zickmüller, Ahmed Mashhour, Klaus Matschke, Utz Kappert,

Traumatic Brain Injury and Neurovascular Disturbances

An open operation on the aortic arch is a complex procedure that requires not only surgical expertise but also meticulous management to ensure excellent outcomes. In recent years, the procedure has often been performed with the patient under circulatory arrest, with antegrade cerebral perfusion. With such a strategy, efficient monitoring to ensure adequate cerebral perfusion is essential. Here we describe a case of Stanford type A aortic dissection repair in which transcranial Doppler sonography was used as an excellent monitoring tool to allow visualization of cerebral flow and the online status of perfusion, providing instant feedback to allow changes in strategy to optimize inadequate cerebral perfusion. An open operation on the aortic arch is a complex procedure that requires not only surgical expertise but also meticulous management to ensure excellent outcomes. In recent years, the procedure has often been performed with the patient under circulatory arrest, with antegrade cerebral perfusion. With such a strategy, efficient monitoring to ensure adequate cerebral perfusion is essential. Here we describe a case of Stanford type A aortic dissection repair in which transcranial Doppler sonography was used as an excellent monitoring tool to allow visualization of cerebral flow and the online status of perfusion, providing instant feedback to allow changes in strategy to optimize inadequate cerebral perfusion. CD has been seen as an innovative, flexible, accessible tool for the bedside monitoring of static and dynamic cerebral flow and treatment response [1Rasulo F.A. De Peri E. Lavinio A. Transcranial Doppler ultrasonography in intensive care.Eur J Anaesthesiol Suppl. 2008; 42: 167-173Crossref PubMed Scopus (77) Google Scholar]. It is also capable of monitoring cerebral vasoreactivity [1Rasulo F.A. De Peri E. Lavinio A. Transcranial Doppler ultrasonography in intensive care.Eur J Anaesthesiol Suppl. 2008; 42: 167-173Crossref PubMed Scopus (77) Google Scholar, 2Sloan M.A. Alexandrov A.V. Tegeler C.H. et al.Assessment: transcranial Doppler ultrasonography: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.Neurology. 2004; 62: 1468-1481Crossref PubMed Scopus (496) Google Scholar]. Its use for intraoperative monitoring has also been described for cardiac procedures such as coronary artery bypass grafting and valve operation [2Sloan M.A. Alexandrov A.V. Tegeler C.H. et al.Assessment: transcranial Doppler ultrasonography: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.Neurology. 2004; 62: 1468-1481Crossref PubMed Scopus (496) Google Scholar, 3Naqvi J. Yap K.H. Ahmad G. Ghosh J. Transcranial Doppler ultrasound: a review of the physical principles and major applications in critical care.Int J Vasc Med. 2013; 2013: 629378PubMed Google Scholar, 4Doblar D.D. Intraoperative transcranial ultrasonic monitoring for cardiac and vascular surgery.Semin Cardiothorac Vasc Anesth. 2004; 8: 127-145Crossref PubMed Scopus (30) Google Scholar]. However, only few published reports have described the use of transcranial duplex (TCD) sonography for cerebral flow monitoring in complex surgical procedures on the aorta [5Neri E. Sassi C. Barabesi L. et al.Cerebral autoregulation after hypothermic circulatory arrest in operations on the aortic arch.Ann Thorac Surg. 2004; 77: 72-79Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar]. Here we report a case in which TCD sonography was used to monitor and optimize cerebral flow in a case of surgical management of a Stanford type A aortic dissection. A 43-year-old man patient was admitted to the internal medicine department of a referring hospital because of severe dyspnea and peripheral edema. Lobar pneumonia was diagnosed and treated accordingly. However, the edema was found to be the result of global cardiac decompensation. The echocardiographic findings included severe aortic regurgitation with a suspected dissecting aneurysm of the ascending aorta. Transesophageal echocardiography and contrast-enhanced computed tomography angiography (CTA) confirmed the diagnosis. The CTA confirmed a dissection of the whole aorta, showing a diameter of 52 mm for the ascending aorta and 32 mm for the aortic arch, with dissection of the left common carotid artery. The patient was then referred to our department for surgical management. The decision was made for an emergency procedure that included a Bentall procedure with the patient under moderate hypothermic circulatory arrest with antegrade selective cerebral perfusion (SCP). The patient was intubated and prepared in a standard manner. Pressure monitoring was achieved by the placement of three arterial lines, one in each radial artery and one in the left femoral artery. An electroencephalogram (EEG) was used for neurologic monitoring. The TCD sonography was performed transtemporally from the patient's left side by use of using a standard S4 echocardiography probe (Fig 1) and achieved satisfactory visualization of the circle of Willis with adequate communicator vessels (Fig 2). The decision was made to use unilateral antegrade SCP.Fig 2Transcranial duplex sonogram before selective cerebral perfusion, showing the right middle cerebral artery (M1), the left middle cerebral artery (M2), the right and left anterior cerebral arteries (A1 and A2, respectively), the left posterior cerebral artery (P2), and the right and left posterior communicators (C1 and C2, respectively).View Large Image Figure ViewerDownload (PPT) After median sternotomy, the pericardium was opened, and the aortic arch and all supraaortic branches were dissected and prepared. Cardiopulmonary bypass (CPB) was applied by arterial cannulation of the brachiocephalic trunk and venous cannulation of the right atrium. Once the patient's core temperature had been lowered to 28°C, the CPB flow was decreased to 1.5 L/min and the three supra-aortic vessels were clamped, marking the beginning of SCP under continuous TCD sonographic monitoring. The TCD sonography showed adequate right hemispheric perfusion with antegrade flow; however, there was a failure of cross-filling over the communicators to the left middle cerebral artery, despite confirmation of their adequacy by preoperative TCD sonography (Fig 3). On the basis of on this finding, the CPB flow was increased to 2.0 L/min and the PCO2 was increased to 45 mm Hg to achieve cerebral vasodilatation during continuous TCD sonographic monitoring. The maneuver resulted in reopening of the communicators with adequate cross-filling and perfusion of the left middle cerebral artery (Fig 4). The distal anastomosis of the aortic graft was then performed. The new aortic prosthesis was clamped, and the supraaortic clamps were released, marking the end of SCP, and the CPB flow was then raised to 5 L/min. The procedure was then completed in a standard manner with no adverse events.Fig 4Transcranial duplex sonogram after optimization of selective cerebral perfusion, showing still adequate flow in the right middle cerebral artery (M1), opening of the posterior communicators (C1 and C2) with adequate perfusion, and adequate perfusion of the left middle cerebral artery (M2). Notice the reversal of flow direction (blue to red) in the left posterior communicator (C2) compared with its flow before selective cerebral perfusion. This is because it is now perfused from the right posterior communicator, not the left middle cerebral artery.View Large Image Figure ViewerDownload (PPT) The patient did well postoperatively, with no signs of neurologic deficit. He was released 1 week after the procedure for rehabilitation. Using TCD sonography for cerebral perfusion monitoring provides a unique chance for real-time intraoperative visualization of the flow. The changes taking place can be readily seen and analyzed, with no lag between the event and its monitoring. In contrast to near-infrared spectroscopy, TCD provides real-time visualization of the state of cerebral perfusion over the circle of Willis. The continuous real-time feedback in this case enabled the surgical team to optimize the antegrade cerebral perfusion. By monitoring the cerebral vasoreactivity and increasing the PCO2 and CPB flow with subsequent reopening of the cerebral communicators, it was possible to provide adequate perfusion for both hemispheres. Had the maneuver not been successful, the surgical team would have had to switch to bilateral perfusion, which was not favorable in this case because of dissection of the left common carotid. Flow monitoring with TCD sonography both indicated the need to optimize the flow and confirmed the adequacy of subsequent flow. We therefore conclude that TCD sonography is an excellent adjunct monitoring method for cerebral perfusion, and its routine use in open surgical procedures on the aortic arch should be seriously discussed. This study was funded by the Dresden Heart Center University Hospital.