Fabien Koskas, Julien Gaudric CHU Pitié-Salpêtrière, Paris, France Prevention of spinal ischemia during repair of descending (DTA) or thoracoabdominal aortic aneurysms (TAA) Fabien Koskas, Julien Gaudric CHU Pitié-Salpêtrière, Paris, France Grateful thanks to the organizers of this meeting, I was asked to play the case against routine CSF drainage during Thoracic endovascular aortic repair

PROTECTION MEDULLAIRE Clampage médullaire Hémodynamique Ischémie médullaire Hypoxie Hyperpression LCR

PROTECTION MEDULLAIRE Potentiels évoqués somesthésiques/moteur Clampage médullaire Diminution métabolisme médullaire Hypothermie profonde / péridurale Perfusion aortique distale CEC/shunts Clampage court <30mn Ischémie médullaire Identification et réimplantation de l’A. d’Adamkiewicz Pharmacologie (papavérine intrathécale etc…) Identification groupes à risque Artifices techniques

PROTECTION MEDULLAIRE Contrôle tensionnel per op -clampage proximal -déclampage CEC Clampage médullaire Hémodynamique Contrôle tensionnel post-op Paraplégies 2aires Ischémie médullaire Contrôle pertes sanguines Cell saver, récupérateurs

PROTECTION MEDULLAIRE Clampage médullaire Hémodynamique Ischémie médullaire Hypoxie Oxygénateur/CEC PaO2 post op exclusion pulm G

PROTECTION MEDULLAIRE Clampage médullaire Hémodynamique Ischémie médullaire Hypoxie Hyperpression LCR Drainage per et post opératoire

Personal experience Open surgery of DTA-TAA From January ninety to December 2000 four hundred twenty six patients were electively operated upon in our service for a DTA or a TAA. Twenty two percent were dissecting aneurysms. There were 144 DTAs

Mechanisms of postoperative paraplegia after T(EV)AR Reversible intraoperative spinal ischemia Reperfusion injury Breakdown of cellular membranes : edema Spinal compression injury Irreversible spinal ischemia Permanent suppression of the spinal blood supply by the aortic procedure Thromboembolic events within the spinal blood supply Poor perioperative systemic hemodynamics The mechanisms of postoperative paraplegia after thoracic aortic repair, endovascular or not, are notoriously multiple : Reversible intraoperative spinal ischemia Reperfusion injury with a cascade initiated by the breakdown of cellular membranes and worsened by edema, CSF hypertension and spinal compression injury Irreversible spinal ischemia by permanent suppression of the spinal blood flow by the aortic procedure itself or its thromboembolic consequences And even poor systemic hemodynamics

Vascularisation médullaire ASP ASA ADK: D8-L2=85% Si ADK<D12: A radiculaire thor moy entre D7-D8 Kieffer E, in Techniques modernes en chirurgie vasculaire 2007 Lazorthes G et al. Arterial vascularization of the spinal cord. J Neurosurg 1971;35:253-62

480 personal cases using exhaustive spinal angiograpy This graph shows in our personal experience of 480 cases studied before aortic repair using exhaustive spinal angiography, the probability that a certain metameric aortic level give rise to a spinal artery, with the superior dorsal in white, the middle dorsal in grey and the Adamkiewicz in black. This is one of the reasons why paraplegia has been seldom reported even after the cure of high aortic lesions like coarctation 480 personal cases using exhaustive spinal angiograpy J Vasc Surg 2002;35:262-8.

AK> AK= AK? AK< Ann Vasc Surg 1989;3:34-46. In our institution we were lucky enough to benefit early from the collaboration of excellent neuroradiologists. This encouraged us at systematically screening all patients using exhaustive spinal angiography before thoracic aortic repair. Basically, preoperative spinal angiography helps at classifying the case into four classes of spinal risk depending whether the main spinal blood supply arises from above the lesion, below the lesion, in the middle of the lesion or is unknown AK< Ann Vasc Surg 1989;3:34-46.

Risk of paraplegia/paresis after open surgical repair of TAA Type % Class I 15 Ak> <10 II 15-40 Ak< III 10 Ak= 5-50* IV Ak? 50 This a summary of one of our previous works on the spinal risk after open surgery of TAA. The topographic type of the aneurysm is a recognized predictor, with a higher risk in types I and II However, the class according to the level of arising of the Adamkiewicz is an even better predictor, the higher risk being observed where the adamkiewicz arises from the lesion or from an unknown level. *Depending upon spinal arterial reattachment Ann Vasc Surg 1989;3:34-46.

Spinal angiography & Results A spinal angiogram was obtained in 77 % of our cases. The Adamkiewicz arose above the lesion in 10 % of these, below the lesion in 7 %, at the level of the lesion in 54 % and was not seen on this spinal angiogram in seven % Even in the group of DTAs spinal arteries arose from the lesion in 15% of the cases and from an unknown part in one percent Among the 144 cases treated of a DTA, the rate of postoperative paraplegia was 1% while the rate of paraparesis was 6%. Of course, the figure is completely different for TAA cases type I and II but it is another story

Risk of paraplegia/paresis after endovascular repair Unknown Probably globally lesser than after open surgery Selection bias Better perioperative hemodynamics Conservation of collateral pathways Very low, especially in the Ak> and Ak< groups Not null, especially whenever Ak= or Ak? What about the risk of paraplegia after endovascular repair. Despite the fact that most reports are encouraging, we must acknowledge that the risk is unknown. It is probably lower than after open surgery for several reasons : A selection bias while best candidates for EVAR are often the most limited lesions intraoperative hemodynamics are better EVAR conserves much of the native collateral network of the spinal blood supply We think that the spinal risk is especially low in the Ak above and Ak below groups. However this risk is certainly not null, especially in the groups where the spinal blood supply arises from the lesion to be covered by the graft or is unknown

Spinal angio versus spinal imaging Exhaustive spinal angio (ESA) is our gold standard, especially for open surgery of TAAs II ESA is technically demanding, time consuming, expensive and invasive EVAR might require a less exhaustive evaluation : selective spinal imaging (SSI) With modern CT technology, more and more cases can benefit from SSI without the need of another acquisition than that necessary to document the aortic lesion* Of course it may be answered that exhaustive spinal angio which is our gold standard before open surgery is technically demanding, time consuming, expensive and at least as invasive as blind CSF drainage. We think that EVAR requires a less exhaustive spinal arterial evaluation than open surgery and allows for a shifting from exhaustive spinal angio to selective spinal imaging a concept I will explain in the next slide. With modern CT technology more and more cases can benefit from selective spinal imaging without any catheterization, using the same acquisition as that used to document the aortic lesion. * Kawaharada et al. Eur J Cardiothorac Surg 2002;21:970-4. * Yoshioka K et al. Radiographics 2003;23:1215-25

This is a beatiful example wher the Adamkiewicz was found arising from the first lumbar artery using CT

Principles of selective spinal imaging Explore all intercostal arteries to be covered by the stent-graft and adjacent With multislice CT (16 bit +), using the same acquisition as that taken for imaging the aortic lesion With sequential catheterization only in case of a failure Classify according to the result Selective spinal imaging means that all intercostal arteries to be covered by the stent-graft and adjacent must be screened Using multislice CT or with selective catheter techniques only in case of a failure of CT. With our present 16 bit CT machines and algorithms more than half of the patients do not need a spinal angio It is easy to bet that with the evolution of CT and even MRI techniques, the rate will augment in the next months or years. With selective spinal imaging, classification of a case before EVAR becomes cost effective

Methods of spinal protection Spinal revascularization Distal perfusion Spinal or general hypothermia Spinal drainage Intrathecal or IV drugs Papaverin, steroïds , calcium blockers, radical scavengers, barbiturates, naloxone, PGEI, allopurinol, oxygen carriers etc… There have been several proposed methods of spinal protection, including : Spinal revascularization Distal perfusion Spinal or general hypothermia Spinal drainage Intra-thecal or IV drugs But none definitely proved it’s efficiency despite some theoretical, experimental or clinical evidence Among the last drugs, we personally found the use of intrathecal papaverin useful

Spinal revascularization Systematic and blind Never Selective Size, topography and backflow of intercostal arteries Intra-operative monitoring (evoked potentials) Pre-operative spinal angiography Among these methods of spinal protection, spinal revascularization by reimplantation of intercostal arteries seems logical and is the most popular among surgeons. Few authors choose to systematically reimplant all available intercostal arteries. Such method is difficult, time-consuming and carries a risk of intra-operative hemorrhage and late aneurysmal degeneration of the aortic buttons. There are also very few authors who never reimplant any intercostal artery and rely upon collateral circuits to provide blood supply to the spine. The situation in this case is quite different from that of stent-grafts where the efficiency of collateral circuits is not altered by the surgical approach or intra-operative hemodynamic disturbances . Such method is only tolerable when dealing with short lesions at distance from the usual aortic segments giving rise to the Adamkiewicz. Most of us use a selective approach. The choice of the intercostal arteries to reimplant may be based upon the size, the topography and the backflow of such arteries. However such method is relatively blind and carries well known risks. Intra-operative monitoring based upon evoked potentials has the definite advantage of testing the functional result of the suppression of an intercostal artery. However, such method is quite difficult to organize in our experience and needs intra-operative decision making. We therefore prefer to base selective spinal revascularization upon the findings of preoperative spinal angiography.

Distal perfusion Improves the hemodynamic tolerance to cross-clamping Reduces the duration of visceral and spinal ischemia Distal perfusion also contributes to spinal protection by reducing the duration of ischemia and by improving the hemodynamic tolerance to cross-clamping

Methods of distal perfusion Passive shunt Extra-anatomic bypass Active shunt Cardio-pulmonary bypass Better control of flow Better oxygen transfer Better control of temperature But necessitates high doses of heparin Among the several methods of distal perfusion, passive shunts, extra-anatomic bypass, active shunt, cardiopulmonary bypass is the preferred choice of many because of a better control of the flow, a better oxygen transfer and a better control of temperature. However the price of this is that it necessitates high doses of heparin with a higher intra-operative bleeding

Hypothermic circulatory arrest Visceral (and spinal) protection Avoids difficult or hazardous cross-clamping Dissection Redo surgery Inflammatory aneurysm Eases the anastomosis by the use of an open technique But Bleeding Sub-optimal myocardial protection through thoracotomy among cardiac patients One other advantage of cardiopulmonary bypass is that it permits the use deep hypothermia and circulatory arrest. Such method provides optimal visceral and spinal protection for long and difficult procedures and eases the making of the proximal anastomoses by the use of an open technique, without the need of proximal cross-clamping. This can be extremely helpful when dealing with pathologies where proximal control and cross-clamping is difficult and hazardous like in dissection, redo or inflammatory cases. However, circulatory arrest has definitely the cost of higher intra-operative bleeding. Also, through thoracotomy, myocardial protection relies only upon hypothermia and this may prove insufficient among cardiac patients.

These are the two circuits that we use most often These are the two circuits that we use most often. The one one on the right, that uses the pulmonary artery is well adapted to case treated using hypothermic arrest

Methods 21 % of the cases were operated upon using simple cross-clamping. The majority of these were short DTAs or type IV TAA.. 56% were operated upon using cardio-pulmonary bypass while 23% were done using a deep hypothermic circulatory arrest.

Syndrôme compartimental médullaire P(LCR) PA Ischémie Ischémie-Reperfusion PPerf Med ≈ PA(aortique distale) -P(LCR) PA :  lors du clampage proximal P(LCR) :  à cause de l’oedeme médullaire  par phénomene de non réabsorption Ne prend pas en compte les résistances artériolo capillaires P veineuse Delayed onset of neurological deficit:signifiance and management.HuynhT et al.Sem in Vasc Surg 2000

CSF drainage does not target any other mechanism of postoperative paraplegia However it must be pointed out that CSF drainage does not target any other mechanism of postoperative paraplegia than compression injury after reversible ischemia and reperfusion

CSF drainage is useful at reducing post-ischemic compression injury 27. Miyamoto K, Ueno A, Wada T, Kimoto S. A new and simple method of preventing spinal cord damage following temporary occlusion of the thoracic aorta by draining the cerebrospinal fluid. J Cardiovasc Surg (Torino) 1960;1:188-97. 28. Oka Y, Miyamoto T. Prevention of spinal cord injury after cross-clamping of the thoracic aorta. Jpn J Surg 1984;14:159-62. 29. McCullough JL, Hollier LH, Nugent M. Paraplegia after thoracic aortic occlusion: influence of cerebrospinal fluid drainage. Experimental and early clinical results. J Vasc Surg 1988;7:153-60. 30. Svensson LG, Grum DF, Bednarski M, et al. Appraisal of cerebrospinal fluid alterations during aortic surgery with intrathecal papaverine administration and cerebrospinal fluid drainage. J Vasc Surg 1990;11:423-9. 31. Crawford ES, Svensson LG, Hess KR, et al. A prospective randomized study of cerebrospinal fluid drainage to prevent paraplegia after high-risk surgery on the thoracoabdominal aorta. J Vasc Surg 1991;13:36-45; discussion 45-6. 32. Woloszyn TT, Marini CP, Coons MS, et al. Cerebrospinal fluid drainage and steroids provide better spinal cord protection during aortic cross-clamping than does either treatment alone. Ann Thorac Surg 1990;49:78-82; discussion 83. 33. Safi HJ, Campbell MP, Ferreira ML, et al. Spinal cord protection in descending thoracic and thoracoabdominal aortic aneurysm repair. Semin Thorac Cardiovasc Surg 1998;10:41-4. 34. Bethel SA. Use of lumbar cerebrospinal fluid drainage in thoracoabdominal aortic aneurysm repairs. J Vasc Nurs 1999;17:53-8. 35. Coselli JS, LeMaire SA, Schmittling ZC, Koksoy C. Cerebrospinal fluid drainage in thoracoabdominal aortic surgery. Semin Vasc Surg 2000;13:308-14. 36. Safi HJ, Miller CC, 3rd, Huynh TT, et al. Distal aortic perfusion and cerebrospinal fluid drainage for thoracoabdominal and descending thoracic aortic repair: ten years of organ protection. Ann Surg 2003;238:372-80; discussion 380-1. There is a maze of literature, with certain titles going back to the sixties, proving that CSF drainage is useful at reducing post-ischemic compression injury. Among this literature there is even a quite convincing prospective randomized trial proving this usefulness during open surgery. There are also some papers and several unpublished evidences that CSF drainage can reverse some cases of postoperative paraplegia or paresis. And at reversing it in some cases Garutti I, Fernandez C, Bardina A, et al. Reversal of paraplegia via cerebrospinal fluid drainage after abdominal aortic surgery. J Cardiothorac Vasc Anesth 2002;16:471-2. And several unpublished personal cases

Caractéristiques communes Etudes randomisées Caractéristiques communes Type d’études Randomisation du drainage du LCR en chirurgie aortique thoracique. Chirurgie ouverte seulement (≠endovasculaire) Patients ATA à haut risque (type I et II) Technique Drainage LCR par ponction lombaire Autres techniques de protection équivalentes dans les groupes cas et témoin : -CEC atriofémorale -réimplantation de l’ADK Objectif Mesure du taux de parésie/paraplégie postopératoire des membres inférieurs -Crawford (JVS, 1991) -Svensson (Annals of Thoracic Surg, 1998) -Coselli (JVS, 2002)

Etudes randomisées -Résultats- Etude Drainage Contrôle LCR vol/pression Drainage postop Crawford 14/46 (30%) 17/52 (33%) 50ml Non Svensson 2/17 (11,8%) 7/16 (43,8%) 7-10 cmH2O 48h Coselli 2/82 (2,7%) 9/74 (12,2%) <10mmHg

Indications du drainage Indic drainage: -ATA I,II,III et IV si réimplantation ADK Quel matériel: -Kit drainage externe du LCR. Sophysa (Tuohy 14G, KT multiperforé 60cm, poche de recueuil)

Indications SSI positive SSI negative Surgical risk Spinal artery(ies) arising from aortic segment to be repaired Adamkiewicz , MDA or SDA SSI negative No spinal artery arising from aortic segment Surgical risk SSI is considered positive if spinal arteries arise from the aortic segment to be covered and negative in the contrary. It is also important to know if it is the artery of Adamkiewicz or a dorsal artery that arises from the critical aortic segment. Of course the general class of surgical risk of the patient is to be considered to take the indication

In this clear cut example of a 26 years old patient with this large intercostal arising from the aneurism and giving rise the artery of Adamkiewicz We did not take the risk of EVAR even with the protection of CSF drainage. The patient was operated openly with reattachment of the intercostal artery. Follow-up was uneventful

SSI negative No CSF drainage Endovascular or open repair in peace of mind When SSI is negative, EVAR is proposed in peace of mind and without CSF drainage

SSI positive Good surgical risk Ak / MDA or SDA with large territory Open surgery with reattachment of critical intercostal arteries using the best spinal protection methods available MDA or SDA with small territory Give objective information to patient If EVAR preferred, CSF drainage, spinal monitoring etc. Retrievable stent-graft* ? Whenever SSI is positive in a good surgical risk patient, and the critical artery is the Adamkiewicz or has a large metameric territory we prefer open surgery with reattachment of critical intercostal arteries and the best available methods of spinal protection, distal perfusion, CSF drainage, papaverin or hypothermia. There is however a discussion if the critical spinal artery is a MDA or a SDA with a small territory. In this case, we think it is extremely important to give unbiased information to the patient. If EVAR is preferred, it is of course done with CSF drainage and the best available methods of spinal monitoring. It is perhaps in these situations that the concept of a retrievable stent-graft is appealing Ishimaru et al, J Thorac Cardiovasc Surg, 1998;115:811 Midorikawa et al. Jpn J Thorac Cardiovasc Surg 2000;48:761-8

SSI positive Poor surgical risk Give information to patient EVAR if feasible CSF drainage Careful monitoring of systemic blood pressure Retrievable stent-graft* under spinal monitoring ? When SSI is positive in a poor risk patient, we follow a similar pattern. Systemic blood pressure control is of a paramount importance in these cases. CSF drainage is of course routinely used. Like others, we develop currently a retrievable stent-graft, using the same technologies as those employed for our custom–made designs. These retrievable implants could be inserted on awake patient or under any method of spinal monitoring like evoked potentials. * Midorikawa et al. Jpn J Thorac Cardiovasc Surg 2000;48:761-8 & personal unpublished designs

Personal results with EVAR 1996-2003 Systematic ESA Only 66 TEVAR cases (612 EVAR cases in the same period) One paraparesis in one hybrid one-stepped elephant trunk under hypothermic circulatory arrest No paraplegia With this general pattern of indications, we treated only 66 cases using EVAR since 1996 without any case of paraplegia but one paraparesis of two months after one complex procedure including a one-stepped stented elephant trunk through sternotomy under hypothermic circulatory arrest for type B dissection

Conclusion Postoperative paraplegia remains a disaster for the patient and a medicolegal concern for surgeons and radiologists Given the low rates of paraplegia after DTA repair and the small number of patients in the series of TAA repair, efficiency of protective methods is difficult to demonstrate The availability of SSI using CT renders blind repair of DTA or TAA questionable