Remote ischemic preconditioning as a means to protect the brain against hypothermic circulatory arrest:an experimental study on piglets

Abstract Open aortic arch surgery almost always requires a bloodless operating field which necessitates the use of hypothermic circulatory arrest. Hypothermic circulatory arrest is a technique where the core temperature of a patient is lowered so that the systemic blood circulation can be stopped momentarily. This can cause unwanted damage to the brain. The risk for neurological impairment is at its highest when corrective surgery has to be performed in emergency situations. This highlights the need for additional neuroprotective methods. Our research group has used a porcine model described in this thesis for about 12 years in various setups to study many neuroprotective hypotheses. We have tested and researched surgical and CPB strategies that could be useful in a HCA and aortic arch reconstruction setting. In this thesis we have combined both chronic surviving animal data with acute experiments and aim to shed light on the mechanisms and efficacy of RIPC as neuroprotective method. In our experimental model, RIPC provided a mitigation of inflammatory response and cerebral injury after prolonged HCA. In general, the collected data showed homogeneity as similar biochemical results were seen in study I and II. Also interestingly, study III and IV possibly shed some light as to the mechanisms of the neuroprotective effect seen in Study II. These results seem to corroborate each other in a logical way. In study I which was acute experiment we saw faster EEG recovery rates in the intervention group. Additionally we recorded beneficial biochemical changes from samples that were collected from the brain. In our chronic study, were the animals were followed for a 7 day period after hypothermic circulatory arrest, we saw a statistically significant neuroprotective effect of remote ischemic preconditioning. In studies III and IV we attempted to shed light on the mechanisms. Study III revealed that an altered oxygen usage profile during hypothermic circulatory arrest and recovery phase might have a role in the neuroprotection. In study IV we saw a reduced microcirculatory leukocyte accumulation in cerebrocortical vessels was noted using an intravital microscope. The intravital microscope also provided results that indicated a difference in the redox state of the mitochondria via NAD+/NADH autofluorescence measurements.Tiivistelmä Sydän- ja aorttakirurgiassa tarvitaan jossain tilanteissa täysin veretöntä leikkausaluetta. Verettömän leikkausalueen saavuttamiseksi joudutaan joskus turvautumaan potilaan elimistön jäähdytyksen jälkeiseen verenkierron pysäytykseen. Tämän menetelmän haittana on kuitenki aivokudokselle aiheutuva hapenpuute ja tästä mahdollisesti seuraava vaurioituminen. Vaurioitumisen riski on korkeimillaan erityisesti päivystyksellisissä tilanteissa. Tämän tutkimuksen tavoitteena on ollut selvittää, onko esialtistavalla raajaiskemialla kykyä suojata aivokudosta hapenpuutostilanteissa. Tutkimusryhmämme on viimeisen 12 vuoden aikana tutkinut sianporsailla eri keinoja, joilla voitaisiin parantaa aivojen suojausta sydän- ja aorttakirurgian aikana. Esialtistava raajaiskemia toteutetaan kiristämällä mansetti eläimen oikean takajalan ympärille. Tämän jälkeen mansetti täytetään viiden minuutin välein neljästi. Täyttökertojen välissä pidettään viiden minuutin tauko, jolloin mansetti on avatuna ja jalan verenkierto palautuu normaaliksi. Ensimmäisessä tutkimuksessamme totesimme, että esialtistava raajiskemia vaikuttaa aivojen sähkökäyrän toipumista nopeuttavasti. Toisessa tutkimuksessamme seurasimme koe-eläimiä seitsemän päivän ajan kokeen jälkeen. Tämän tutkimuksen yhteydessä toteutessa aivokudoksen mikroskooppiananalyysissä havaitsimme, että raajaiskemia vaikutti suojaavan aivokudosta hapenpuutteen aiheuttamilta aivovaurioilta. Kolmanessa tutkimuksessa selvitimme, että raajaiskemia vaikuttaa aivojen happipitoisuuteen sekä verenkierron pysäytyksen aikana että toipumisvaiheessa. Viimeisessä tutkimuksessa kuvasimme aivojen pintaverisuonia mikroskoopilla. Seurasimme kokeessa valkosolujen käyttäytymistä aivokudoksessa käyttäen fluoresoivia lääkeaineita. Havaitsimme, että raajaiskemiaryhmässä valkosoluja oli aivokudoksen pintaverisuonissa merkittävästi vähemmän. Lisäksi samalla menetelmällä tutkimme sitruunahappokiertoon osallistuvan NAD+/NADH parin suhteita autofluoresenssi ilmiöllä. Autofluorensenssi tutkimuksen tulokset viittaavat siihen, että mitokondrioiden hapetus/pelkistys kyky oli parempi raajaiskemia ryhmässä. Kokeissamme esialtistava raajaiskemia vähensi tulehdussolujen määrää aivokudoksessa sekä vähensi aivovauriota hapenpuutteen jälkeen

Results of intention-to-treat pulmonary metastasectomies in northern Finland revealing significant number of new lung primary carcinomas:time to move on from wedge resections?

Abstract Background: A considerable proportion of intended pulmonary metastasectomies is known to turn out as new incidental primary lung cancers in final pathology. We aimed to analyse the trends and results of pulmonary metastasectomies using the intention-to-treat approach with an emphasis on final histopathological findings. Methods: All intention-to-treat pulmonary metastasectomies performed in Oulu University Hospital between 2000 and 2020 were included in the study. Long term survival was analysed with the Kaplan-Meier method and log-rank tests. A binary logistic regression analysis was performed to calculate odds ratios for incidental primary lung cancer in final histology. Results: A total of 154 intended pulmonary metastasectomies were performed to 127 individual patients. There was an increasing trend in pulmonary metastasectomies during the study period. Despite the increasing trend in comorbidities of the operated patients, the length of hospital stays decreased, and the postoperative complication rates remained stable. In final pathology reports, 9.7% were new primary lung cancers and 13.0% were benign nodules. A long disease-free interval (≥24 months) and smoking history were associated with incidental primary lung cancer in final histology. The short-term 30- and 90-day mortalities after pulmonary metastasectomy were 0.7%. The 5-year survival after pulmonary metastasectomy from all histologies was 52.8%, and from colorectal cancer metastasectomies (n=34) it was 73.5%. Conclusions: The significant amount of new primary lung cancer lesions in pulmonary metastasectomy specimens highlight the diagnostic importance of pulmonary metastasectomy. A segmentectomy could be considered as a primary procedure in pulmonary metastasectomy in patients with a long disease-free interval and a heavy smoking history

Thirty years of esophageal cancer surgery in Oulu University Hospital

Abstract Background: Esophagectomy is the mainstay of surgical treatment of esophageal cancer, but involves high operative risk. The aim of this study was to review the evolution surgical treatment of esophageal cancer in Northern Finland, with introduction of minimally invasive techniques. Methods: All elective esophagectomies performed in Oulu University Hospital between years 1987 and 2020 were included. Treatment strategies were compared to current guidelines including staging and use of neoadjuvant therapy, and benchmark values including postoperative morbidity, hospital stay, readmissions and 90-day mortality. Long-term survival was compared to previous national studies. Results: Between years 1987 and 2020 a total of 341 underwent an esophagectomy. Transhiatal resection was performed to 167 (49.3%), Ivor Lewis to 129 (38.1%) and McKeown to 42 (12.4%) patients. MIE was performed to 49 (14.5%) patients. During the past four years 83.7% of locally advanced diseases received neoadjuvant treatment. Since 1987, gradual improvements have occurred especially in incidence of pleural effusion requiring additional drainage procedure (highest in 2011–2013 and in last four years 14.0%), recurrent nerve injuries (highest in 2008–2010 29.4% and lowest in 2017–2020 1.8%) and in 1-year survival rate (1987–1998 68.4% vs. 2017–2020 82.1%). No major changes in comorbidity, complication rate, anastomosis leaks, hospital stay or postoperative mortality were seen. Conclusions: Esophageal cancer surgery has gone through major changes over three decades. Current guideline-based treatment has resulted with progressive improvement in mid- and long-term survival. However, despite modern protocol, no major improvement has occurred for example in major complications, anastomosis leak rates or hospital stay

Minimally invasive esophagectomy learning curves with different types of background experience

Abstract Background: Minimally invasive esophagectomy (MIE) is a complex procedure with learning associated morbidity. The aim was to evaluate the learning curve for MIE focusing on short-term outcomes in two settings: (I) experienced MIE surgeon in new hospital (Hospital 1); (II) surgeons experienced with open esophagectomy and minimally invasive surrogate surgery (Hospital 2). Methods: In Hospital 1 and Hospital 2, on intent-to-treat basis number of MIEs were 132 and 57, respectively. The primary outcomes were major complications and anastomosis leaks. Secondary outcomes were operative time, blood loss, lymph node yield, hospital stay and 1-year mortality. Length of learning curves were analyzed with risk-adjusted cumulative sum (RA-CUSUM) method. Results: In Hospital 1, major complication and anastomosis leak rates were 9.8% and 4.5%, 22.8% and 12.3% in Hospital 2, respectively. In Hospital 1, complication and leak rates remained stable. In Hospital 2, improvement occurred after 34 cases in major complications and 29 cases in leaks. Of secondary outcomes, improvements were seen in Hospital 1 in operative time after 61, blood loss after 86, lymph node yield after 52, hospital stay after 19 and 1-year mortality after 24 cases. In Hospital 2, improvement occurred in operative time after 30, blood loss after 15, lymph node yield after 45, hospital stay after 50 and 1-year mortality after 15 cases. Conclusions: According to this study, learning phase of the individual surgeon determines the outcomes of MIE, not the institutional learning phase

Thromboembolisms related to post-operative electrical cardioversions for atrial fibrillation in patients with surgical aortic valve replacement

Abstract Aims: Post-operative atrial fibrillation (POAF) is a frequent complication after open-heart surgery, and cardioversions (CV) are commonly performed to restore sinus rhythm. However, little data exists on thrombo-embolic risk related to early post-operative CV and on the recurrence of POAF after CV. CAREAVR study sought to assess the rate of strokes, transient ischaemic attacks (TIA), and mortality shortly after POAF-triggered CV in patients who underwent isolated surgical aortic valve replacement (SAVR) with a bioprosthesis. Methods and results: Altogether 721 patients underwent isolated SAVR with a bioprosthesis at four Finnish university hospitals. During post-operative hospitalization, after patients with prior chronic AF were excluded, 309/634 (48.7%) of patients had at least one episode of POAF [median time (interquartile range) 3 (3) days], and an electrical CV was performed in 113/309 (36.6%) of them. The length of hospital stay was not affected by CV. At 30 days follow-up, the rate of stroke, TIA or mortality was higher in those AF patients who underwent CV vs. those who did not (9.7% vs. 3.6%, P = 0.04, respectively; adjusted hazard ratio 2.63, 95% confidence interval 1.00–6.92, P = 0.05). Similar proportion of patients in both groups were in AF rhythm at discharge (32.7% vs. 35.7%, P = 0.18); and at 3 months (25.0% vs. 23.6%, P = 0.40), respectively. Conclusion: In this real-world population of patients undergoing isolated SAVR, the rate of POAF was nearly 50%. One-third of these patients underwent an electrical CV, and they exhibited over two-fold risk for thromboembolisms and mortality. Cardioversion did not affect the short-term prevalence of AF

Occurrence and classification of cerebrovascular events after isolated bioprosthetic surgical aortic valve replacement:a competing risk analysis of the CAREAVR study

Abstract Background: The long-term incidence of stroke and the proportion of cardioembolic events after bioprosthetic surgical aortic valve replacement (SAVR) remain largely unknown. Methods: The CAREAVR study sought to assess the rate of stroke and transient ischemic attack (TIA) in patients who underwent isolated surgical aortic valve replacement with a bioprosthesis at four Finnish university hospitals between 2002 and 2014. Data was collected retrospectively and included 721 patients. Median follow-up time was 4.8 [3.0–7.0] years. Results: At 5 years, freedom from stroke was 89.0%, from TIA 94.1%, and from stroke and TIA 83.7%. The median time between index procedure and stroke or TIA was 1.7 years [29 days–3.9 years]. Stroke was of cardioembolic origin in 44.4% of patients. In multivariable competing risk analysis, increased age (HR 1.03, 95%CI 1.00–1.06, p = 0.022), previous stroke or TIA (HR 1.75, 95%CI 1.14–2.70, p = 0.010), New York Heart Association (NYHA) class III or more (HR 1.51, 95%CI 1.01–2.24, p = 0.044) and insulin treatment at discharge (HR 1.20, 95%CI 1.09–3.64, p = 0.024) were independent predictors of stroke or TIA. Cerebrovascular events occurred in 47.2% of patients with ongoing anticoagulation therapy. Conclusion: In this study, the incidence of stroke in the early postoperative period after bioprosthetic SAVR was higher than previously documented. Almost half of strokes were of cardioembolic etiology. These findings highlight the need for the better prevention strategies for cardioembolic events after bioprosthetic SAVR

Performance of CHA2DS2-VASc score for stroke prediction after surgical aortic valve replacement

Abstract Objective: Stroke is a frequent complication occurring early and late after surgical aortic valve replacement. There is an unmet clinical need for simple tools to assess postoperative stroke risk. We sought to assess the predictive performance of Congestive heart failure; Hypertension; Age ≥75 (doubled); Diabetes mellitus; prior Stroke, transient ischemic attack or thromboembolism (doubled); Vascular disease; Age 65 to 74; Sex category (female) (CHA₂DS₂-VASc) score in patients undergoing surgical aortic valve replacement with a bioprosthesis. Methods: Seven hundred fourteen patients undergoing isolated surgical aortic valve replacement with a bioprosthesis at 4 university hospitals were included. Data were collected retrospectively from patient records and monitored by an independent party. Results: Median follow-up time was 4.8 years. Mean CHA₂DS₂-VASc score was 4.1 ± 1.6. Low (scores, 0–1), high (scores, 2–4), and very high (scores, 5–9) CHA₂DS₂-VASc scores were observed in 39 (5.5%), 400 (56.0%), and 262 (38.5%) patients, respectively. Incidences of stroke or transient ischemic attack at 1 year were 2.6%, 4.8%, and 10.7%; at 5 years incidences were 5.2%, 14.0%, and 21.9%; and at 10 years incidence were 5.2%, 20.7%, and 37.9% for patients in low, high, and very high scores, respectively. Incidences of major bleeds at 1 year were 0%, 1.8%, and 2.7%; at 5 years incidences were 0%, 5.4%, and 8.7%; and at 10 years incidences were 0%, 9.0%, and 27.1%, respectively. Competing risk analysis showed that patients with CHA₂DS₂-VASc score of 5 through 9 had a significantly increased risk of stroke or transient ischemic attack (hazard ratio, 4.75; 95% confidence interval, 1.09–20.6; P = .037) irrespective of preoperative or new-onset in-hospital atrial fibrillation compared with low-risk patients. Conclusions: CHA₂DS₂-VASc is a valuable tool to identify patients with increased risk of stroke and major bleeding, and for whom alternative strategies for prevention of late neurologic complications should be adopted

Tertiary lymphoid structures in pulmonary metastases of microsatellite stable colorectal cancer

Abstract Tertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates located at sites of chronic inflammation and recognized as prognosticators in several cancers. We aimed to analyse the prognostic effect of TLSs in colorectal cancer (CRC) pulmonary metastases and primary tumours, with a comparison to the CD3+ and CD8+ cell density-based immune cell score (ICS). For TLS density and TLS maximum diameter analysis, 67 pulmonary metastases and 63 primary tumours were stained with haematoxylin and eosin. For ICS scoring and analysis, CD3 and CD8 immunohistochemistry was performed. Excellent interobserver agreement was achieved in all TLS measurements. Of all patients, 36 patients had low TLS density (< 0.222 follicles/mm) and 31 patients had high TLS density (≥ 0.222 follicles/mm) in the first resected pulmonary metastases. TLS density (adjusted HR 0.91, 0.48–1.73) or maximum diameter (adjusted HR 0.78, 0.40–1.51) did not have prognostic value in pulmonary metastases. In primary tumours, higher TLS density (adjusted HR 0.39, 0.18–0.87) and maximum diameter (adjusted HR 0.28, 0.11–0.73) were associated with lower mortality. In the pulmonary metastases, ICS had superior prognostic value to TLSs; however, TLSs and ICS were significantly associated. In conclusion, TLSs in CRC pulmonary metastases had no prognostic value but correlated with the ICS. TLSs in primary tumours associated with favourable prognosis

The prognostic role of tumor budding and tumor-stroma ratio in pulmonary metastasis of colorectal carcinoma

Abstract Objective: To evaluate the prognostic value of tumor budding and tumor-stroma ratio (TSR) in resected pulmonary metastases of colorectal carcinoma (CRC). Methods: In total, 106 pulmonary metastasectomies were performed to 74 patients in two study hospitals during 2000–2020. All relevant clinical data were retrospectively collected. Tumor budding based on the International Tumor Budding Consensus Conference recommendations and TSR in the first resected pulmonary metastases and primary tumors were evaluated from diagnostic hematoxylin-eosin-stained histopathological slides. Results: 60 patients (85.7%) had low tumor budding (≤5 buds/field) and 10 patients (14.3%) had high tumor budding (>5 buds/field) in their first pulmonary metastases of CRC. 5-year overall survival rates of pulmonary metastasectomy in low and high total tumor budding were 28.3% and 37.3% (p = 0.387), respectively. 19 patients (27.1%) had low TSR and 51 patients (72.9%) had high TSR. The 5-year overall survival rates were 32.9% in low and 28.6% in high TSR of first pulmonary metastases (p = 0.746). Tumor budding and TSR did not provide prognostic value in Cox multivariate analysis. Tumor budding and TSR in resected pulmonary metastases were not associated with those of the primary tumor. Conclusion: Tumor budding and TSR in the resected pulmonary metastases of CRC showed no statistically significant prognostic value, however, additional well-powered confirmatory studies are needed