Mechanisms of angiogenesis and lymphangiogenesis in calcific aortic valve stenosis

Aortic valve stenosis (AVS) is the most common valvular disease in Western countries. Pharmacological prevention of AVS having proved unsuccessful, its current treatment is still valve replacement. The etiology of AVS is multifactorial, both genetic and external risk factors predisposing to the active pathological process eventually leading to clinically manifest stenosis. Histological features of the disease resemble those of atherosclerosis, including the accumulation and modification of lipoproteins, inflammation, extracellular matrix remodeling, and calcification. Furthermore, valvular interstitial cells undergo phenotypic differentiation into actively proliferating myofibroblasts, which contribute to the local inflammatory response as well as extracellular matrix remodeling in stenotic aortic valves. Blood vessels also grow into the normally avascular valve leaflets already in the early stages of the disease. This thesis aimed at elucidating the mechanisms behind the pathological neovascularization of the stenotic aortic valves. Furthermore, we characterized valvular lymphangiogenesis and investigated potential factors contributing to the balance between valvular angiogenesis and lymphangiogenesis, focusing on the role of valvular myofibroblasts and mast cells. For this purpose, we studied a total of 117 stenotic valves obtained at valve replacement surgery, and 49 control valves obtained at cardiac transplantations, at valve replacement surgery due to aortic valve regurgitation, or from deceased organ donors whose hearts were unsuitable for use as grafts. The valve leaflets were either used freshly for myofibroblast cell culture or frozen for e.g. PCR and immunohistochemical analyses. First, we assessed the adverse extracellular matrix remodeling of stenotic aortic valves, a process necessary for angiogenic sprouting to occur. We found that the mRNA expression levels of cathepsins S, K, and V, and their inhibitor cystatin C were higher in stenotic aortic valves than in control valves. Furthermore, the total activity of such cathepsins was increased in AVS. In immunohistochemical stainings, the expressions of cathepsin S, cathepsin V, and cystatin C localized to valvular macrophages, chondroblast-like cells, and endothelial cells lining both the valvular surface and the neovessels in the stenotic valves. Next, we characterized the neovessels and lymphatic vessels in stenotic aortic valves and control valves using immunohistochemistry. We found that in addition to immature microvessels, the stenotic aortic valves contained organized arterioles, indicating an advanced stage of angiogenesis. Lymphatic vessels correlated with valvular blood vessels, but were present in much fewer numbers. Valvular mast cells resided close to neovessels and secreted the angiogenic Vascular endothelial growth factor A (VEGF-A). Furthermore, we showed that the lymphangiogenic growth factors VEGF-C and VEGF-D are locally produced in the aortic valves, and that the receptors for all these VEGFs, VEGFR-2 and VEGFR-3, are upregulated in AVS. We also identified several factors that induce VEGF-A secretion in cultured valvular myofibroblasts. These include mast cell-derived components, the inflammatory cytokine TNF-α, hypoxia, and cigarette smoke. Myofibroblasts were also able to promote VEGF-A secretion by cultured human mast cells, suggesting potential angiogenic interplay between these two valvular cell types. Interestingly, mast cell-derived proteases also efficiently degraded the lymphangiogenic growth factor VEGF-C. Thus, by secreting VEGF-A, by urging myofibroblasts to produce VEGF-A, and by releasing VEGF-C-degrading proteases, mast cells may strongly influence the observed imbalance between valvular blood vessels and lymphatic vessels. Finally, we investigated the potential effects of oxidized low-density lipoprotein (oxLDL) on valvular angiogenesis. We found that oxLDL induces the expression of several inflammatory cytokines in cultured myofibroblasts. Moreover, we identified oxLDL-binding scavenger receptors to be locally expressed in the aortic valves. The mRNA expression levels of scavenger receptor class A type 1 (SR-A1) and Lectin-like oxidized LDL receptor-1 (LOX-1) were increased in AVS, whereas CD36 was downregulated in stenotic valves. Furthermore, the expression of LOX-1 in cultured valvular myofibroblasts increased in response to mast cell-derived components and TNF-α. The observed changes in valvular scavenger receptor expression particularly favor inflammation and angiogenesis. In conclusion, several angiogenic factors were found to be activated in stenotic aortic valves. Furthermore, valvular mast cells and myofibroblasts were identified as potential players promoting valvular angiogenesis and contributing to the pathological imbalance between valvular angiogenesis and lymphangiogenesis. This imbalance, in turn, could facilitate the harmful infiltration of inflammatory cells and lipoproteins into the stenotic aortic valves and ultimately contribute to the progression of the disease.Aorttaläpän ahtauma on väestön ikääntymisen myötä yleistynyt sairaus, johon ei ole lääkehoitoa. Aorttaläpän ahtautuminen johtaa sydämen vasemman kammion painekuormitukseen ja lopulta vajaatoimintaan, ja jo taudin lievään muotoon liittyy kohonnut sydänperäisen äkkikuoleman riski. Tauti havaitaan yleensä myöhään, sillä se on pitkään oireeton. Oireiden ilmaantuminen onkin aihe keinoläppätoimenpiteelle. Taudin riskitekijöitä ovat korkean iän lisäksi miessukupuoli, korkea verenpaine, tupakointi, diabetes ja veren suuri LDL-kolesterolin pitoisuus. Vaikka riskitekijät ovat osittain samat kuin sepelvaltimotaudissa, vain noin puolella läppäpotilaista on merkittävä sepelvaltimotauti. Kudostasolla läpän ahtautumiseen johtaa aktiivinen tapahtumaketju, jonka katsotaan alkavan läpän pintaa verhoavan endoteelisolukerroksen vaurioitumisesta. Sitä seuraa tulehdussolujen, kuten syöttösolujen, ja kolesterolin kertyminen läpän rakenteisiin. Lisäksi läpän sidekudossolut aktivoituvat sidekudostumista edistävään suuntaan myofibroblasteiksi ja läpissä tuotetaan runsaasti sidekudosta hajottavia proteaaseja. Normaalisti suonettomiin aorttaläppäliuskoihin kasvaa taudin myötä uudissuonia, jotka voivat edistää tautia kuljettamalla läppiin lisää tulehdussoluja ja rasvoja. Lisäksi verisuonien kuljettamat ravinteet ja happi mahdollistavat tulehdussolujen ja sidekudossolujen haitallisen toiminnan. Imusuonet puolestaan voisivat toimia verisuonien vastavaikuttajina kuljettamalla tulehdussoluja ja rasvoja kudoksista pois. Ahtautuneiden aorttaläppien uudissuonittumisen ja imusuonikasvun taustalla olevat mekanismit ovat kuitenkin tähän asti olleet pitkälti tuntemattomia. Tämän väitöskirjan osatyöt tähtäsivät ahtautuneiden aorttaläppien uudissuonittumisen luonnehdintaan sekä uudissuoni- ja imusuonikasvun taustalla olevien tekijöiden kartoittamiseen. Osatöissä on tutkittu 117 aorttaläpän ahtauman vuoksi leikatun potilaan aorttaläppää. 49 kontrolliläppää kerättiin aorttavuodon vuoksi leikatuilta potilailta, sydämensiirroissa poistetuista sydämistä ja käyttämättä jääneistä sydänsiirteistä. Ensimmäinen osatyö käsitteli katepsiineja S, K, ja V, sekä niiden estäjää kystatiini C:tä. Nämä proteaasit osallistuvat sidekudoshajotukseen, joka on välttämätöntä uusien verisuonien versoamiselle. Toisessa ja kolmannessa osatyössä selvitimme uudissuonten ja imusuonten määrää ja laatua ahtautuneissa ja terveissä aorttaläpissä sekä niiden yhteyksiä läpän kalkkiutumiseen ja tulehdusasteeseen. Lisäksi eristimme ihmisen aorttaläpistä myofibroblasteja ja tutkimme niiden vastetta erilaisiin ärsykkeisiin, kuten tulehdusvälittäjäaineisiin, hapenpuutteeseen ja tupakansavuun. Lisäksi tutkimme myofibroblastien ja syöttösolujen vaikutuksia toisiinsa soluviljelymallissa ja osoitimme, että niiden välisellä vuorovaikutuksella voi olla uudissuonittumista edistäviä vaikutuksia. Neljännessä osatyössä selvitimme aiemmin ahtautuneista läpistä löydettyjen hapettuneiden LDL-hiukkasten vaikutuksia uudissuonittumiseen. Havaitsimme, että näiden hiukkasten vaikutuksia välittävien jätereseptorien ilmentyminen on ahtautuneissa aorttaläpissä muuttunut tulehdusta ja uudissuonittumista edistävään suuntaan. Tässä väitöskirjassa on kuvattu useita ahtautuneiden aorttaläppien uudissuonittumisen mekanismeja. Havaitsimme, että uudissuonten ja imusuonten välinen tasapaino on ahtautuneissa aorttaläpissä häiriintynyt suosien mm. tulehdussolujen kertymistä läpän rakenteisiin. Näin ollen tämän epätasapainon taustatekijät, kuten läpän syöttösolujen ja myofibroblastien vuorovaikutukset, voivat myös edistää aorttaläpän ahtauman etenemistä

Magneettikuvauksen ABC: T1, T2, fat sat, DWI ynnä muut : radiologin salakieli auki kirjoitettuna

Vertaisarvioitu. Näin tutkin.Magneettikuvien tulkinta edellyttää magneettifysiikan perusteiden ymmärtämistä. Magneettikuvaussekvenssejä voidaan painottaa eri tavoin, jolloin kudokset erottuvat erilaisina. Kuvauksissa erilaiset sekvenssit täydentävät toisiaan ja tuovat kukin lisää informaatiota, jolloin syntyy kokonaiskäsitys kuvatusta kohteesta. Käytettävät sekvenssit ovat eri kysymyksenasettelujen yhteydessä erilaisia, ja paikalliset käytännöt voivat vaihdella. Kaikki potilaat eivät kaikissa tilanteissa sovellu magneettikuvaukseen, johon voi liittyä myös turvallisuusriskejä esimerkiksi kehonsisäisten vierasesineiden vuoksi. Radiologin lausunto sisältää kliinikkoa varten tehdyn tulkinnan lisäksi radiologiset perustelut siitä, miten tulkintaan on päädytty. Radiologiset termit helpottavat radiologien keskinäistä kommunikaatiota seurantakuvauksissa, mutta saattavat hämmentää kliinikkoa. Kokoustoiminta tukee perehtymistä oman alan kuvantamiseen sekä edistää kliinikoiden ja radiologien välistä yhteistyötä

Radiologisen kuvantamisen perusteet

Vertaisarvioitu. Näin tutkin.Kuvantamistutkimusten tarkoituksenmukainen käyttö edellyttää kliinikolta oman alansa kuvantamistutkimusten perustuntemusta ja perehtymistä paikallisiin kuvantamiskäytäntöihin. Lähete radiologiseen kuvantamistutkimukseen toimii konsultaatiopyyntönä, ja lähetetiedot vaikuttavat tutkimuksen ajankohtaan, suunnitteluun, suorittamiseen sekä tulkintaan. Natiivikuvaus ja kaikukuvaus ovat usein hyviä ensivaiheen tutkimuksia, jotka voivat ohjata jatkotutkimuksia ja hoitoa oikeaan suuntaan, vaikkei niiden avulla aina päästäisikään diagnoosiin. Läpivalaisu-, tietokonetomografia (TT)- ja magneettikuvaukset kuuluvat pääosin erikoissairaanhoitoon, ja niistä saa toisiaan täydentävää lisätietoa. Toimenpiteisiin lähetettäessä on tärkeää kertoa potilaalle toimenpiteen kulusta ja huomioida myös veren hyytymiseen vaikuttava lääkitys. Epäselvissä tapauksissa radiologille kannattaa soittaa. Parhaimmillaan kliinikon ja radiologin välinen hyvä yhteistyö parantaa potilaan hoitoketjua ja kohtuullistaa kuvantamisen alati suurenevia kokonaiskustannuksia

Cardiac magnetic resonance in giant cell myocarditis : a matched comparison with cardiac sarcoidosis

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Peak flow measurements in patients with severe aortic stenosis : a prospective comparative study between cardiovascular magnetic resonance 2D and 4D flow and transthoracic echocardiography

Background Aortic valve stenosis (AS) is the most prevalent valvular disease in the developed countries. Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) is an emerging imaging technique, which has been suggested to improve the evaluation of AS severity compared to two-dimensional (2D) flow and transthoracic echocardiography (TTE). We investigated the reliability of CMR 2D flow and 4D flow techniques in measuring aortic transvalvular peak systolic flow in patients with severe AS. Methods We prospectively recruited 90 patients referred for aortic valve replacement due to severe AS (73.3 +/- 11.3 years, aortic valve area 0.7 +/- 0.1 cm(2), and 54/36 tricuspid/bicuspid), and 10 non-valvular disease controls. All the patients underwent echocardiography and 2D flow and 4D flow CMR. Peak flow velocity measurements were compared using Wilcoxon signed rank sum test and Bland-Altman analysis. Results 4D flow underestimated peak flow velocity in the AS group when compared with TTE (bias - 1.1 m/s, limits of agreement +/- 1.4 m/s) and 2D flow (bias - 1.2 m/s, limits of agreement +/- 1.6 m/s). The differences between values obtained by TTE (median 4.3 m/s, range 2.7-6.1 m/s) and 2D flow (median 4.5 m/s, range 2.9-6.5 m/s) compared to 4D flow (median 3.1 m/s, range 1.7-5.1 m/s) were significant (p < 0.001). The difference between 2D flow and TTE were insignificant (bias 0.07 m/s, limits of agreement +/- 1.5 m/s). In non-valvular disease controls, peak flow velocity was measured higher by 4D flow than 2D flow (1.4 m/s, 1.1-1.7 m/s and 1.3 m/s, 1.1-1.5 m/s, respectively; bias 0.2 m/s, limits of agreement +/- 0.16 m/s). Conclusions CMR 4D flow significantly underestimates systolic peak flow velocity in patients with severe AS. 2D flow, in turn, estimated the AS velocity accurately, with measured peak flow velocities comparable to TTE.Peer reviewe

Inter- and Intra-Observer Variability and the Effect of Experience in Cine-MRI for Adhesion Detection

Cine-MRI for adhesion detection is a promising novel modality that can help the large group of patients developing pain after abdominal surgery. Few studies into its diagnostic accuracy are available, and none address observer variability. This retrospective study explores the inter- and intra-observer variability, diagnostic accuracy, and the effect of experience. A total of 15 observers with a variety of experience reviewed 61 sagittal cine-MRI slices, placing box annotations with a confidence score at locations suspect for adhesions. Five observers reviewed the slices again one year later. Inter- and intra-observer variability are quantified using Fleiss’ (inter) and Cohen’s (intra) κ and percentage agreement. Diagnostic accuracy is quantified with receiver operating characteristic (ROC) analysis based on a consensus standard. Inter-observer Fleiss’ κ values range from 0.04 to 0.34, showing poor to fair agreement. High general and cine-MRI experience led to significantly (p &lt; 0.001) better agreement among observers. The intra-observer results show Cohen’s κ values between 0.37 and 0.53 for all observers, except one with a low κ of −0.11. Group AUC scores lie between 0.66 and 0.72, with individual observers reaching 0.78. This study confirms that cine-MRI can diagnose adhesions, with respect to a radiologist consensus panel and shows that experience improves reading cine-MRI. Observers without specific experience adapt to this modality quickly after a short online tutorial. Observer agreement is fair at best and area under the receiver operating characteristic curve (AUC) scores leave room for improvement. Consistently interpreting this novel modality needs further research, for instance, by developing reporting guidelines or artificial intelligence-based methods.</p

Inter- and Intra-Observer Variability and the Effect of Experience in Cine-MRI for Adhesion Detection

Cine-MRI for adhesion detection is a promising novel modality that can help the large group of patients developing pain after abdominal surgery. Few studies into its diagnostic accuracy are available, and none address observer variability. This retrospective study explores the inter- and intra-observer variability, diagnostic accuracy, and the effect of experience. A total of 15 observers with a variety of experience reviewed 61 sagittal cine-MRI slices, placing box annotations with a confidence score at locations suspect for adhesions. Five observers reviewed the slices again one year later. Inter- and intra-observer variability are quantified using Fleiss’ (inter) and Cohen’s (intra) κ and percentage agreement. Diagnostic accuracy is quantified with receiver operating characteristic (ROC) analysis based on a consensus standard. Inter-observer Fleiss’ κ values range from 0.04 to 0.34, showing poor to fair agreement. High general and cine-MRI experience led to significantly (p < 0.001) better agreement among observers. The intra-observer results show Cohen’s κ values between 0.37 and 0.53 for all observers, except one with a low κ of −0.11. Group AUC scores lie between 0.66 and 0.72, with individual observers reaching 0.78. This study confirms that cine-MRI can diagnose adhesions, with respect to a radiologist consensus panel and shows that experience improves reading cine-MRI. Observers without specific experience adapt to this modality quickly after a short online tutorial. Observer agreement is fair at best and area under the receiver operating characteristic curve (AUC) scores leave room for improvement. Consistently interpreting this novel modality needs further research, for instance, by developing reporting guidelines or artificial intelligence-based methods

Safe Deferral of Coronary Computed Tomography Angiography for Patients With a Low Pretest Probability of Coronary Artery Disease in 2019 European Society of Cardiology Guidelines

Background Coronary computed tomography angiography is increasingly used as the first‐line test for suspected coronary artery disease. Its overuse in a low pretest probability (PTP) population may lead to low diagnostic yield without change in patient management. We evaluated the clinical consequences of the updated 2019 European Society of Cardiology (ESC) chronic coronary syndromes guidelines’ PTP estimation and whether imaging could be safely deferred in patients with a low PTP. Methods and Results This retrospective cohort included all 1753 consecutive patients who underwent coronary computed tomography angiography for suspected coronary artery disease at Helsinki University Hospital between 2009 and 2017. PTP was calculated according to the 2013 and 2019 ESC guidelines. The overall mortality, cardiac deaths, myocardial infarctions, and hospitalizations for unstable angina were acquired from national registry data for 1 to 10 years of follow‐up (median, 4 years). Updated 2019 ESC guidelines classified 72% of the patients as having low PTP, whose imaging could have been deferred. The revascularization rate (4.7%) and annual cardiac mortality (0.4%) were low in the 857 patients reclassified from the recommendation to test, according to the 2013 ESC guideline, to deferral of coronary computed tomography angiography, according to the new 2019 guideline. Conclusions The updated 2019 ESC guideline PTP score aids clinicians in safely preventing the overuse of cardiac imaging in patients deemed at low PTP of coronary artery disease. Diagnostic yield, revascularization rate, and cardiac mortality are low in patients with low pretest risk

Impact of Atrial Fibrillation on the Symptoms and Echocardiographic Evaluation of Patients With Aortic Stenosis

Atrial fibrillation (AF) is common in patients with aortic stenosis (AS) and complicates the assessment of AS severity. The overlapping of symptoms in these 2 conditions may postpone valve replacement. This study aimed to evaluate the effect of AF on the severity assessment of AS and its impact on symptoms and quality of life (QoL). Patients with severe AS were prospectively recruited. Echocardiography, symptom questionnaires, and RAND-36 QoL assessment were performed preoperatively and 3 months postoperatively. The aortic valve calcium score (AVC) was measured using computed tomography. Of the 279 patients, 74 (26.5%) had AF. Patients with AF had lower mean gradients and 45.9% had a low-gradient phenotype, with a mean gradient <40 mm Hg, compared with 22.4% of those without AF (p <0.001). The AVC measurements revealed severe valve calcification equally in patients with or without AF (85.7% vs 87.7%, p = 0.78). Patients with AF were more symptomatic at baseline, with 50.0% versus 27.3% in New York Heart Association class III or higher (p <0.001), and after intervention. Patients with AF had more residual dyspnea (27.3% vs 12.0%, p = 0.007) and exercise intolerance (36.4% vs 17.0%, p = 0.002). The QoL improved significantly in both groups but was worse at baseline in patients with AF and remained impaired after intervention. In conclusion, low-gradient AS phenotype is overrepresented in patients with AF, but they have equally severe stenosis determined using AVC, despite the lower gradients. Patients with AF have more symptoms and worse QoL, but they improve significantly after intervention. In patients with AF, multimodality imaging is important in the assessment of AS severity.Peer reviewe

Cardiac magnetic resonance -detected myocardial injury is not associated with long-term symptoms in patients hospitalized due to COVID-19

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