Spinal cord injury during selective cerebral perfusion and segmental artery occlusion: an experimental study

OBJECTIVESSince selective cerebral perfusion (SCP) has been used in aortic arch surgical procedures, the core temperature during lower body circulatory arrest (LBCA) has been steadily rising. Simultaneously, the use of a frozen elephant trunk (FET) graft has been increasing. The safe period of LBCA in relation to spinal cord ischaemic tolerance in combination with segmental artery occlusion by the FET procedure has not been defined.METHODSSixteen pigs were assigned to undergo 65 (n = 10) or 90 min (n = 6) of SCP at 28°C with LBCA in combination with occlusion of the 8 uppermost segmental arteries in the thoracic (Th) aorta (15–20 cm FET, Th8-level). The follow-up period consisted of a 6-h intensive period and a 5-day observation period. Near-infrared spectroscopy of the collateral network was used to determine spinal cord oxygenation. The neurological status of the patients was evaluated daily, and the brain and the spinal cord were harvested for a histopathological analysis.RESULTSFive out of 6 pigs after 90 min and 1 out of 10 pigs after 65 min of LBCA died within 48 h of multiorgan failure. Of the survivors in the 65-min group, 6 out of 9 had paraparesis/paraplegia; the remaining 3 reached normal function. The lone survivor after 90 min of LBCA was paraplegic. Nadir near-infrared spectroscopy of the collateral network values at Th8 and Th10 were 34 (±5) and 39 (±4), and they were reached within 35 min of SCP in both groups.CONCLUSIONSAn extended FET graft with LBCA and SCP durations >65 min at 28°C results in a poor outcome.</p

Late Outcome after Surgery for Type-A Aortic Dissection

The aim of this study was to evaluate all-cause mortality and aortic reoperations after surgery for Stanford type A aortic dissection (TAAD). We evaluated the late outcome of patients who underwent surgery for acute TAAD from January 2005 to December 2017 at the Helsinki University Hospital, Finland. We studied 309 patients (DeBakey type I TAAD: 89.3%) who underwent repair of TAAD. Aortic root repair was performed in 94 patients (30.4%), hemiarch repair in 264 patients (85.4%) and partial/total aortic arch repair in 32 patients (10.4%). Hospital mortality was 13.6%. At 10 years, all-cause mortality was 34.9%, and the cumulative incidence of aortic reoperation or late aortic-related death was 15.6%, of any aortic reoperation 14.6%, reoperation on the aortic root 6.6%, on the aortic arch, descending thoracic and/or abdominal aorta 8.7%, on the descending thoracic and/or abdominal aorta 6.4%, and on the abdominal aorta 3.8%. At 10 years, cumulative incidence of reoperation on the distal aorta was higher in patients with a diameter of the descending thoracic aorta >= 35 mm at primary surgery (cumulative incidence in the overall series: 13.2% vs. 4.0%, SHR 3.993, 95%CI 1.316-12.120; DeBakey type I aortic dissection: 13.6% vs. 4.5%, SHR 3.610, 95%CI 1.193-10.913; patients with dissected descending thoracic aorta: 15.8% vs. 5.9%, SHR 3.211, 95%CI 1.067-9.664). In conclusion, surgical repair of TAAD limited to the aortic segments involved by the intimal tear was associated with favorable survival and a low rate of aortic reoperations. However, patients with enlarged descending thoracic aorta at primary surgery had higher risk of late reoperation. Half of the distal aortic reinterventions were performed on the abdominal aorta.Peer reviewe

Long-term outcomes after ascending aortic replacement and aortic root replacement for type A aortic dissection

OBJECTIVES: We investigated whether the selective use of supracoronary ascending aorta replacement achieves late outcomes comparable to those of aortic root replacement for acute Stanford type A aortic dissection (TAAD). METHODS: Patients who underwent surgery for acute type A aortic dissection from 2005 to 2018 at the Helsinki University Hospital, Finland, were included in this analysis. Late mortality was evaluated with the Kaplan-Meier method and proximal aortic reoperation, i.e. operation on the aortic root or aortic valve, with the competing risk method. RESULTS: Out of 309 patients, 216 underwent supracoronary ascending aortic replacement and 93 had aortic root replacement. At 10 years, mortality was 33.8% after aortic root replacement and 35.2% after ascending aortic replacement (P = 0.806, adjusted hazard ratio 1.25, 95% confidence interval, 0.77-2.02), and the cumulative incidence of proximal aortic reoperation was 6.0% in the aortic root replacement group and 6.2% in the ascending aortic replacement group (P = 0.65; adjusted subdistributional hazard ratio 0.53, 95% confidence interval 0.15-1.89). Among 71 propensity score matched pairs, 10-year survival was 34.4% after aortic root replacement and 36.2% after ascending aortic replacement surgery (P = 0.70). Cumulative incidence of proximal aortic reoperation was 7.0% after aortic root replacement and 13.0% after ascending aortic replacement surgery (P = 0.22). Among 102 patients with complete imaging data [mean follow-up, 4.7 (3.2) years], the estimated growth rate of the aortic root diameter was 0.22 mm/year, that of its area 7.19 mm(2)/year and that of its perimeter 0.43 mm/year. CONCLUSIONS: When stringent selection criteria were used to determine the extent of proximal aortic reconstruction, aortic root replacement and ascending aortic replacement for type A aortic dissection achieved comparable clinical outcomes.Peer reviewe

Late Outcome after Surgery for Type-A Aortic Dissection

The aim of this study was to evaluate all-cause mortality and aortic reoperations after surgery for Stanford type A aortic dissection (TAAD). We evaluated the late outcome of patients who underwent surgery for acute TAAD from January 2005 to December 2017 at the Helsinki University Hospital, Finland. We studied 309 patients (DeBakey type I TAAD: 89.3%) who underwent repair of TAAD. Aortic root repair was performed in 94 patients (30.4%), hemiarch repair in 264 patients (85.4%) and partial/total aortic arch repair in 32 patients (10.4%). Hospital mortality was 13.6%. At 10 years, all-cause mortality was 34.9%, and the cumulative incidence of aortic reoperation or late aortic-related death was 15.6%, of any aortic reoperation 14.6%, reoperation on the aortic root 6.6%, on the aortic arch, descending thoracic and/or abdominal aorta 8.7%, on the descending thoracic and/or abdominal aorta 6.4%, and on the abdominal aorta 3.8%. At 10 years, cumulative incidence of reoperation on the distal aorta was higher in patients with a diameter of the descending thoracic aorta >= 35 mm at primary surgery (cumulative incidence in the overall series: 13.2% vs. 4.0%, SHR 3.993, 95%CI 1.316-12.120; DeBakey type I aortic dissection: 13.6% vs. 4.5%, SHR 3.610, 95%CI 1.193-10.913; patients with dissected descending thoracic aorta: 15.8% vs. 5.9%, SHR 3.211, 95%CI 1.067-9.664). In conclusion, surgical repair of TAAD limited to the aortic segments involved by the intimal tear was associated with favorable survival and a low rate of aortic reoperations. However, patients with enlarged descending thoracic aorta at primary surgery had higher risk of late reoperation. Half of the distal aortic reinterventions were performed on the abdominal aorta

Methods of spinal cord protection in aortic surgery:experimental porcine studies

Abstract Paraplegia is one of the most devastating complication after surgery for thoracic or thoracoabdominal aortic aneurysm. Despite the modern protection strategies utilized prior to, during and after the surgery, the risk of permanent paraplegia remains. In the repair of acute type A aortic dissection, selective cerebral perfusion (SCP) and lower body circulatory arrest (LBCA) are widely used operative methods to protect the central nervous system. The temperature used during SCP and LBCA has gradually been rising, which has not necessarily been beneficial for the spinal cord. New methods to protect the spinal cord and eliminate the possibility of permanent paraplegia are needed. Ischaemic preconditioning was first introduced in the 1980s in myocardial protection, while remote ischaemic preconditioning (RIPC) was introduced in the 1990s. In experimental studies, RIPC has proven to be an effective method to protect the spinal cord from ischaemia. Nonetheless, to date, there is no evidence for its potential in aortic aneurysm surgery in a clinical setting. The complete mechanism by which RIPC exerts its protective action is also unknown. Ischaemic priming by occluding the segmental arteries in an elective setting before the surgical treatment of the aortic aneurysm is a promising new method in protection of the spinal cord from ischaemic insult. However, to our knowledge, ischaemic priming of the spinal cord has not yet been attempted in an acute setting. The studies presented in this thesis were carried out as a chronic porcine study. The main objective of the studies was spinal cord protection during ischaemic insult. Study I demonstrated the protective effect of RIPC against spinal cord ischaemia. Pigs treated with RIPC exhibited a faster neurological recovery and preferable near-infrared spectroscopy values four hours after the spinal cord ischaemia compared to control pigs. In study II, acute ischaemic priming led to improved neurological recovery, lower lactate discharge and fewer histopathologic changes in the spinal cord compared to control pigs. In study III, LBCA and SCP in a simulated frozen elephant trunk operation with extent stent craft resulted in a disastrous outcome when the LBCA time was 65 minutes.Tiivistelmä Rinta- tai rinta-vatsa-aortan aneurysman korjausleikkauksen yksi pahimmista mahdollisista komplikaatioista on pysyvä alaraajahalvaus huolimatta tänä päivänä käytössä olevista selkäytimen suojausmenetelmistä. Akuutin tyypin A aortan dissekaation korjausleikkauksen aikana selektiivinen aivoperfuusio ja verenkierron hypoterminen pysäyttäminen ovat usein käytettyjä metodeja suojata aivoja ja muita iskemialle alttiita kudoksia. Avustetun aivoperfuusion ja kehon hypotermisen verenkierron pysäytyksen lämpötilaraja on kuitenkin viime vuosien aikana hiljalleen noussut korkeammaksi, eikä tämä välttämättä ole selkäytimen suojauksen kannalta paras mahdollinen tilanne. Uusia selkäytimen suojausmenetelmiä tarvitaan edelleen, jotta pysyvän alaraajahalvauksen riski olisi mahdollisimman pieni. Sydämen suojaamisessa käytettävä iskeeminen esialtistus esiteltiin kirjallisuudessa 1980-luvulla. Seuraavalla vuosikymmenellä kirjallisuudessa esiteltiin myös etäinen iskeeminen esialtistus. Sittemmin kokeellisissa tutkimuksissa on osoitettu, että etäinen iskeeminen esialtistus suojaa selkäydintä iskeemiseltä vauriolta. Iskeemisestä esialtistuksesta tai etäisestä iskeemisestä esialtistuksesta ei toistaiseksi ole aikasempaa näyttöä aneurysmakirurgian yhteydessä. Niin ikään iskeemisen esialtistuksen tai etäisen iskeemisen esialtistuksen vaikutusmekanismia ei tunneta vielä tarkasti. Elektiivisessä aortan aneurysmakirurgiassa selkäytimen ja sen kollateraaliverenkierron iskeeminen esikäsittely on uusi ja lupaava keino suojata selkäydintä tulevan kirurgisen korjaustoimenpiteen aikana. Selkäytimen iskeemisen esikäsittelyn vaikutusta ei ole aikaisemmin tutkittu akuutissa tilanteessa. Tässä väitöskirjatyöksi tarkoitetussa tutkimuksessa tutkittiin ja selvitettiin selkäytimen suojaamista iskeemiseltä vauriolta. Tutkimus toteutettiin käyttäen apuna kokeellista eläinmallia. Ensimmäisessä tutkimuksessa osoitettiin etäisen iskeemisen esialtistuksen johtavan nopeampaan neurologiseen toipumiseen ja parempaan selkäytimen ja tämän kollateraalisuonten verenkiertoon selkäydiniskemian jälkeen. Toisessa tutkimuksessa selkäytimen iskeeminen esikäsittely johti parempaan neurologiseen paranemiseen ja matalampaan leikkauksen aikaiseen laktaattipäästöön. Lisäksi selkäytimen histopatologinen analyysi osoitti, että selkäytimen vauriot olivat vähäisempiä. Kolmannessa tutkimuksessa todettiin, että jo 65 minuutin selektiivinen aivoperfuusio ja muun verenkierron pysäytys 28 asteen lämpötilassa yhdistettynä jäljiteltyyn ”Frozen elephant trunk” leikkausmenetelmään johti katastrofaaliseen lopputulokseen

Direct Aortic versus Peripheral Arterial Cannulation in Surgery for Type-A Aortic Dissection

Background It is controversial whether peripheral arterial cannulation may achieve better results than direct aortic cannulation during surgery for Stanford type A aortic dissection (TAAD). Methods Three-hundred and nine consecutive patients underwent surgical repair for acute TAAD from January 2005 to December 2017 at the Helsinki University Hospital, Finland. The early outcomes of patients who underwent surgery with direct aortic cannulation were compared with those in whom peripheral arterial cannulation was employed. Results Direct aortic cannulation was employed in 80 patients and peripheral arterial cannulation in 229 patients. Patients who underwent surgery with direct aortic cannulation had hospital mortality (13.8% vs. 13.5%, p=0.962) and stroke/global brain ischemia (22.3% vs. 25.0%, p=0.617) similar to those with peripheral arterial cannulation. The other secondary outcomes were equally distributed between the unmatched study cohorts. Among 74 propensity score matched pairs, direct aortic cannulation had hospital mortality (12.2% vs. 9.5%, p=0.804) and stroke/global brain ischemia rates (21.6% vs. 21.6%, p=1.000) comparable to peripheral arterial cannulation. The composite outcome of hospital mortality/stroke/global brain ischemia (29.7% vs. 27.0%, p=0.855), multiple stroke (16.2% vs. 17.6%, p=1.000), renal replacement therapy (11.8% vs. 13.0%, p=1.000) and length of stay in the intensive care unit (mean, 4.9±4.5 vs. 4.8±4.9 days, p=0.943) were also equally distributed between these matched cohorts. Conclusions In this institutional series, central arterial cannulation allowed a straightforward surgical repair of TAAD and achieved similar early outcomes to those of peripheral arterial cannulation.Peer reviewe

Diazoxide Attenuates Ischemic Myocardial Injury in a Porcine Model

Background: We hypothesized that diazoxide, a mitochondrial ATP-sensitive potassium channel opener, has cardioprotective effects during acute myocardial ischemia. Diazoxide is suggested to act through protein kinase Ce (PKC epsilon) activation. Methods: Twelve piglets were randomly assigned to receive intravenous infusion of diazoxide (3.5 mg/kg) with solvent or only solvent (6 animals per group) before cardiac ischemia. Myocardial ischemia was induced by occluding the left circumflex artery (LCX) for 40 minutes. The reperfusion and follow-up period lasted for three hours. Throughout the experiment hemodynamic measurements and blood samples were collected, and after the follow-up period the hearts were harvested for transmission electron microscopy (TEM) as well as histopathological and immunohistochemical analyses. Results: TEM showed less ischemic damage on a cellular level in the diazoxide group (P = .004) than in the control group. Creatinine kinase MB levels (Pt*g = .030) were lower, and oxygen consumption (Pt*g = .037) and delivery (Pg = .038) were higher in the diazoxide group compared to the controls. Conclusion: Diazoxide preserves myocardial cellular structure and cellular function, and thus it may have benefits in treating ischemic myocardial injury.Peer reviewe

Spinal cord injury during selective cerebral perfusion and segmental artery occlusion:an experimental study

Abstract Objectives: Since selective cerebral perfusion (SCP) has been used in aortic arch surgical procedures, the core temperature during lower body circulatory arrest (LBCA) has been steadily rising. Simultaneously, the use of a frozen elephant trunk (FET) graft has been increasing. The safe period of LBCA in relation to spinal cord ischaemic tolerance in combination with segmental artery occlusion by the FET procedure has not been defined. Methods: Sixteen pigs were assigned to undergo 65 (n = 10) or 90 min (n  = 6) of SCP at 28°C with LBCA in combination with occlusion of the 8 uppermost segmental arteries in the thoracic (Th) aorta (15–20 cm FET, Th8-level). The follow-up period consisted of a 6-h intensive period and a 5-day observation period. Near-infrared spectroscopy of the collateral network was used to determine spinal cord oxygenation. The neurological status of the patients was evaluated daily, and the brain and the spinal cord were harvested for a histopathological analysis. Results: Five out of 6 pigs after 90 min and 1 out of 10 pigs after 65 min of LBCA died within 48 h of multiorgan failure. Of the survivors in the 65-min group, 6 out of 9 had paraparesis/paraplegia; the remaining 3 reached normal function. The lone survivor after 90 min of LBCA was paraplegic. Nadir near-infrared spectroscopy of the collateral network values at Th8 and Th10 were 34 (±5) and 39 (±4), and they were reached within 35 min of SCP in both groups. Conclusions: An extended FET graft with LBCA and SCP durations >65 min at 28°C results in a poor outcome