O expressivo número de brasileiros que necessitam correção anatômica da estenose valvar aórtica acentuada e que não realizam cirurgia de substituição valvar devido ao risco proibitivo justifica a necessidade de investigação, tanto da efetividade no cenário clínico real quanto dos custos impostos ao Sistema Único de Saúde e aos planos de saúde suplementar brasileiros pela incorporação do implante transcateter de valva aórtica, que tem se demonstrado efetivo mas oneroso, internacionalmente. No primeiro artigo da tese, avaliaram-se os desfechos intra-hospitalares, a sobrevida e o reembolso pela internação hospitalar de 41 pacientes com idade média de 78,7 ± 6,3 anos, estenose valvar aórtica acentuada, com recusa cirúrgica e decisão multidisciplinar por tratamento transcateter entre outubro de 2010 e outubro de 2015. Os sujeitos foram seguidos prospectivamente por um período mediano de 15,2 (4,5 – 25,6) meses e a sobrevida estimada em 1 e 2 anos foi de 73,2% e 64,1%, respectivamente. Identificou-se que hipertensão pulmonar e revascularização miocárdica cirúrgica prévia estavam independentemente associadas à menor sobrevida. O valor mediano reembolsado pelos pacientes atendidos pelo Sistema Único de Saúde foi R$ 108.634,34 (101.051,05 – 127.255,27) e R$ 115.126,77 (94.603,21 – 132.603,01) para aqueles internados por planos de saúde suplementar ou particulares, sendo o respectivo valor mediano reembolsado pela prótese valvar de R$ 82.000,00 (82.000,00 – 95.450,00) e 84.050,00 (75.000,00 – 92.400,00) Em um grupo de 585 procedimentos de troca valvar aórtica cirúrgica em indivíduos com idade ≥ 60 anos, realizados entre janeiro de 2010 e dezembro de 2015 na mesma instituição, a mortalidade intra-hospitalar estava associada à idade e foi de 5,9% naqueles com idade entre 60 e 70 anos, 10,8% entre 70 e 80 anos e de 22,2% ≥ 80 anos. O reembolso mediano foi de R$ 14.035,96 (11.956,11 – 16.644,90) para os internados pelo Sistema único de Saúde e R$ 20.273,97 (15.358.03 – 32.815,49) pelos planos de saúde suplementar ou particulares. No segundo artigo da tese, identificou-se que do total de 819 pacientes consecutivamente incluídos no Registro Brasileiro de Implante de Bioprótese Aórtica por Cateter entre janeiro de 2008 e outubro de 2015, 15 (1,8%) sofreram perfuração do ventrículo esquerdo. Os pacientes que apresentaram perfuração eram mais idosos (85,4 ± 6,3 vs. 81,5 ± 7,3 anos, p=0,038), predominantemente mulheres (80,0% vs. 50,5%, p=0,024), apresentavam maior fração de ejeção (67,3 ± 7,8% vs. 58,6 ± 15,0%, p=0,001), menor massa ventricular esquerda (203,9 ± 47,1g vs. 247,6 ± 78,7g, p=0,039) e menor altura do tronco da coronária esquerda (11,2 ± 5,4mm vs. 14,0 ± 3,3mm, p=0,034). Os preditores independentes de perfuração do ventrículo esquerdo foram idade e fração de ejeção. No terceiro artigo, descreve-se um caso de ablação septal para tratamento de miocardiopatia hipertrófica obstrutiva assimétrica para posterior implante transcateter de valva aórtica, sugerindo que esta seja uma estratégia factível quando da concomitância dessas duas condições Em conclusão, os desfechos do tratamento transcateter da estenose valvar aórtica acentuada em pacientes inoperáveis são compatíveis com aqueles do cenário idealizado dos ensaios clínicos randomizados, apesar de estarem associados a custos maiores que os anteriormente estimados por painéis de especialistas. O tratamento cirúrgico, por sua vez, apresentou mortalidade maior que aquela idealizada ou relatada como usual. A hipercinesia do ventrículo esquerdo pode favorecer o trauma determinado pelo guia metálico, posicionado em seu interior para realização do procedimento, estando a fração de ejeção independentemente associada à chance de perfuração. Ainda, a ablação septal por álcool eletiva, anterior ao implante transcateter da valva aórtica, é uma abordagem factível para pacientes com hipertrofia ventricular esquerda assimétrica obstrutiva associada à estenose valvar aórtica. / The expressive number of Brazilians who require an anatomic correction for severe aortic valve stenosis and who do not undergo valvar replacement surgery due to prohibitive risk justifies the need to investigate both the effectiveness in the real clinical scenario and the costs imposed to the Public Health System and the Supplementary Health System for the incorporation of the transcatheter aortic valve implantation, which has been shown to be effective but onerous, internationally. In the first article of the thesis, the in-hospital outcomes, long-term survival and reimbursement for 41 patients, with a mean age of 78.7 ± 6.3 years, sever aortic valve stenosis, with surgical refusal and multidisciplinary decision for transcatheter treatment, between October 2010 and October 2015 are described. Subjects were prospectively followed for a median period of 15.2 (4.5 - 25.6) months and the estimated survival at 1 and 2 years was 73.2% and 64.1%, respectively. It was identified that pulmonary hypertension and previous coronary artery bypass grafting were independently associated with lower survival. Median reimbursed values by the Public Health System was R$ 108,634.34 (101,051.05 - 127,255.27) and by supplementary health plans was R$ 115,126.77 (94,603.21 - 132,603.01). The respective median values reimbursed for the valve prosthesis was R$ 82,000.00 (82,000.00 - 95,450.00) and 84,050.00 (75,000.00 - 92,400.00) In a group of 585 surgical aortic valve replacement procedures in subjects aged ≥ 60 years, performed between January 2010 and December 2015 in the same institution, in-hospital mortality was associated with age and was 5.9% in those with age between 60 and 70 years, 10.8% between 70 and 80 years and 22.2% in ≥ 80 years. The median reimbursement was R$ 14,035.96 (11,956.11 - 16,644.90) for those hospitalized by the Public Health System and R$ 20,273.97 (15,358.03 - 32,815.49) by supplementary or private health plans. In the second article of the thesis, it was identified that of the total of 819 patients consecutively included in the Brazilian Registry of Aortic Bioprosthesis Implantation by Catheter (RIBAC) between January 2008 and October 2015, 15 (1.8%) suffered perforation of the left ventricle. Patients with perforation were older (85.4 ± 6.3 vs. 81.5 ± 7.3 years, p=0.038), predominantly women (80.0% vs. 50.5%, p=0.024), had a higher ejection fraction (67.3 ± 7.8% vs. 58.6 ± 15.0%, p=0.001), lower left ventricular mass (203.9 ± 47.1g vs. 247.6 ± 78, 7g, p=0.039) and shorter distance between the aortic annulus and the left main coronary artery ostium (11.2 ± 5.4mm vs. 14.0 ± 3.3mm, p=0.034). The independent predictors of left ventricular perforation were age and ejection fraction. In the third article, a case of septal ablation was described for the treatment of asymmetric obstructive hypertrophic cardiomyopathy for posterior transcatheter aortic valve implantation, suggesting that this is a feasible strategy when these two conditions are concomitant In conclusion, the outcomes of transcatheter treatment of severe aortic stenosis in inoperable patients are compatible with those in the ideal scenario of randomized clinical trials, although they are associated with higher costs than previously estimated by expert panels. Surgical treatment, on the other hand, presented higher mortality than that idealized or reported as usual. The left ventricle hyperkinesia may favor the trauma determined by the metallic guide, positioned inside it to perform the procedure, the ejection fraction being independently associated with the chance of perforation. Furthermore, elective alcohol septal ablation, prior to transcatheter aortic valve implantation, is a feasible approach for patients with obstructive asymmetric left ventricular hypertrophy associated with aortic valve stenosis.

Le rétrécissement aortique calcifié dégénératif (RAC) représente la principale pathologie valvulaire cardiaque dans les pays occidentaux (2% à 7% de la population après 65 ans). Il n’existe, à ce jour, aucun traitement médical qui permette de stopper ou de prévenir la progression du RAC. Le seul traitement du RAC sévère est le remplacement valvulaire aortique chirurgical ou par cathétérisme (TAVI) en cas de symptômes (dyspnée,douleur thoracique ou syncope), de dysfonction ventriculaire gauche (FEVG<50%) ou de mauvaise tolérance fonctionnelle lors d’un test d’effort. À l’inverse, la prise en charge des patients asymptomatiques avec un RAC sévère est controversée devant le risque de mort subite ou de détérioration myocardique irréversible sans traitement et le risque de la chirurgie cardiaque prophylactique et des complications prothétiques. De plus, le RAC intéresse une population de plus en plus âgée où la présence de symptômes peut être difficilement évaluable et où s’associent des facteurs de risques et des comorbidités cardiovasculaires rendant la stratégie clinique de plus en plus compliquée. Enfin, il semble que parmi les patients avec un RAC serré asymptomatique, certains sont à plus haut risque d’évènements et bénéficieraient peut être d’une chirurgie plus précoce. L’identification de marqueurs de progression et pronostiques objectifs dans ce sous-groupe de patients constitue donc un enjeu très important. / Aortic valve stenosis (AS) is the most common valvular heart disease in Westerncountries AS (2%–7% of the population after 65 years old) for which valve replacement is theonly curative treatment. Current guidelines recommend surgery in patients with severe ASand either symptoms or left ventricular systolic dysfunction (LVEF<50%). However,treatment of asymptomatic patients remains controversial due, on the one side, to the riskof sudden death without preceding symptoms and irreversible myocardial dysfunction and,on the other side, to the risk of surgery and prosthetic valve complications. Identifyingsubsets of asymptomatic AS patients with preserved left ventricular ejection fraction whomay benefit from early or prophylactic surgery is therefore a critical clinical challenge.

Experiments described in this thesis address the pathogenesis of aortic valve sclerosis/stenosis using a bench to bedside approach. In particular, the thesis begins with development of a technique using ultrasonic backscatter analyses to quantitate the early stages of aortic stenosis. Subsequent chapters utilized this methodology to quantitate aortic valve structural changes in a model and intervention study of aortic stenosis in rabbits. The last chapters are human studies designed to identify factors associated with presence of aortic sclerosis/stenosis; with particular interest in potential association of endothelial dysfunction/inflammation/platelet aggregation with abnormal aortic valve structure quantitated by ultrasonic backscatter. In Chapter 1 (Introduction) the relevant literature is reviewed. Development of ultrasonic backscatter to quantitate aortic sclerosis (Chapter 2) Aortic valve sclerosis (ASc) is detected when there is visual assessment of focal increases in echogenicity of the aortic valve most commonly assessed by echocardiography. However, there is no previously described method to quantitate degree of aortic valve structural abnormality as ASc is not associated with marked hemodynamic obstruction quantifiable by Doppler echocardiography. The current study used ultrasonic backscatter to quantitate aortic valve structural abnormality in patients assessed as having ASc based on valve appearances, compared to young healthy volunteers with normal aortic valves. The results of the study indicate: 1) that the mean levels of aortic valve backscatter in ASc patients are approximately 60% greater than in young healthy volunteers (ie aortic valve backscatter scores ≥ 16dB are not consistent with normal aortic valve structure), 2) ultrasonic backscatter scores in ASc patients are directly correlated with subjective scoring of sclerosis and with a positive trend with transvalvular pressure gradients in patients with mild-moderate aortic stenosis, and most importantly, 3) ultrasonic backscatter is a reproducible technique, with mean differences between estimates based on repeat echocardiograms of 2.3 ± 1.7 (9.1%). These results indicate that ultrasonic backscatter could be used as a quantitative measure of aortic valve structural abnormality in epidemiology and for examination of interventions. In vivo studies Development of an animal model of aortic stenosis with vitamin D2 (Chapter 3) The aim of the study was to develop an appropriate animal model for AS. The study used vitamin D2 alone at 25,000IU/4 days weekly (vit-D2) for 8 weeks to induce AS in rabbits. Results showed that: 1) rabbits in the vit-D2 group had significantly increased in transvalvular velocity and pressure gradients compared to rabbits in the control group (normal chow + drinking water); this was consistent for aortic valve ultrasonic backscatter scores; 2) aortic valve immunohistochemistry/histology showed marked calcification, neutral lipids, macrophage, and leukocyte infiltrations for rabbits in the vit- D2 group (ie consistent with histology of human AS); 3) significant elevation of asymmetric dimethylarginine (ADMA) concentrations in the vit-D2 group occurred compared to controls over the 8 weeks treatment period; the change in ADMA concentrations correlated significantly with the change in transvalvular pressure gradients for rabbits in the vit-D2 group; 4) rabbits in the vit-D2 group had significantly impaired endothelium-dependent acetylcholine-induced aortic relaxation, and this effect was completely abolished by the nitric oxide synthase inhibitor (L-NAME); 5) the addition of 0.5% cholesterol-supplemented diet to the vitamin D2 regimen did not accentuate the development of AS. Thus, treatment with vitamin D2 at 25,000IU/4 days weekly for 8 weeks significantly induced AS with similar aortic valve pathology to that of human AS; therefore, the model is suitable for use in examining potential therapeutic interventions in AS. Effects of ramipril on development of AS in rabbits (Chapter 4) Using this animal model, this study aimed to examine the effects of the angiotensinconverting enzyme inhibitor (ACEi) ramipril on development of AS. Rabbits (n=28) treated for 8 weeks were divided into 2 groups: (a) vitamin D2 alone (n=10) (normal chow + 25,000IU vitamin D2 in drinking water); (b) vitamin D2/Ramipril (n=12) (normal chow+25,000IU vitamin D2/Ramipril (0.5mg/kg) in drinking water). Six further rabbits constituted a normal reference group (no treatment was given). The results for comparisons between vitamin D2/ramipril vs vitamin D2 alone were as follows: 1) ramipril-treated rabbits had significantly less severe hemodynamic obstructions (p<0.05, for both) as assessed by transvalvular velocity, and aortic valve area; with borderline reduction in aortic valve backscatter (p=0.08); 2) ramipril significantly reduced plasma ADMA concentrations; 3) there was improvement in acetylcholine-induced aortic relaxation (p=0.056), with significant improvement in sodium nitroprusside-induced relaxation (p<0.05); 4) there was a strong inverse correlation between acetylcholineinduced aortic relaxation and aortic valve backscatter score (0<0.001), thus providing further evidence of the potential role of nitric oxide in retarding the development of AS in this model. These data provide a strong rationale for the inception of a randomized trial of ACE inhibition as a strategy for limitation of AS progression in humans. Human studies Aortic stenosis is associated with elevated plasma levels of asymmetric dimethylarginine (ADMA) concentrations in humans (Chapter 5). Given the findings that aortic stenosis induced by vitamin D2 in rabbits also caused elevation of plasma ADMA concentrations, a physiological inhibitor of nitric oxide synthase, a mediator and marker of endothelial dysfunction and an indicator of incremental cardiovascular risk. The study sought to determine whether plasma ADMA concentrations are elevated independently of pre-existing coronary risk factors in subjects with at least moderate aortic stenosis (n=42) compared to age-matched patients with normal aortic valves (n=42): as determined both by visual assessment and with aortic valve backscatter scores < 16dB. Results for this study were as follows: 1) plasma ADMA concentrations were not statistically different between the AS and non-AS group (median 0.59 vs 0.54 µmol/L, p=0.13, Mann-Whitney test) on univariate analysis; 2) backward stepwise multiple linear regression showed the presence of AS was a significant predictor of elevated ADMA concentrations (p=0.04, 95% CI =0.001, 0.072). 3) in addition, elevated plasma ADMA concentrations were also associated with history of atrial fibrillation (p=0.009, 95% CI=0.015, 0.100), and negatively associated with creatinine clearance (p=0.01, 95% CI=-0.002, 0.000), and the use of statin therapy (p=0.01, 95% CI=-0.081, -0.011). Therefore, in conclusion, this study found that AS is independently associated with elevation of ADMA concentrations, beyond that implied by “conventional” risk factors for endothelial dysfunction. The clinical status of AS as an incremental marker of cardiovascular risk may reflect ADMA-mediated endothelial dysfunction. Assessment of factors associated with ASc in a random ageing population study (Chapter 6). There have been few clinical studies of factors associated with ASc. Previous population studies have established that ASc is an independent correlate of incremental risk of coronary events. Having established that patients with AS have increased plasma ADMA concentrations (Chapter 5), it was now aimed to determine whether subjects with increased aortic valve backscatter scores (ASc) also have other markers of endothelial dysfunction/NO effects, independent of preexisting coronary risk factors. The study was designed to identify such anomalies, if they existed, on an incremental basis to other putative correlates of ASc, including coronary risk factors, renal dysfunction and vitamin D levels. Random selected subjects (n=253) aged between 51 to 77 years were evaluated. All patients underwent transthoracic echocardiography examination; aortic valve ultrasonic backscatter score (AVBS), was used to quantitate echogenicity of the aortic valve. Conventional coronary risk factors were identified on history. Integrity of NO generation/response was assessed via (i) plasma ADMA concentrations; (ii) inhibition of platelet aggregation by the NO donor sodium nitroprusside (SNP); (iii) aortic augmentation index (AIx), a measure of arterial stiffness/wave reflection. All putative correlations with AVBS were examined by univariate and stepwise multiple linear regression analyses. On the basis of echocardiographic appearances, ASc was present in 63 subjects (25.4%); mean AVBS scores was 14.9±4.6dB (SD) vs 11.2±3.9dB (SD) in the presence vs absence of ASc (p<0.001). Univariate analyses revealed that platelet responsiveness to NO was inversely correlated with AVBS (β=-0.16, p=0.02); but [ADMA] and AIx were not. On multiple linear regression, significant correlates of increased AVBS were: (i) advanced age (β=0.21, p=0.003), (ii) low body mass index (β=-0.23, p=0.001); and (iii) impaired platelet responsiveness to NO (β=-0.16, p=0.02). In Chapter 7, the implications of the overall findings in this thesis are discussed in relation to future perspective. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1309350 / Thesis(Ph.D.) -- School of Medicine, 2008

Experiments described in this thesis address the pathogenesis of aortic valve sclerosis/stenosis using a bench to bedside approach. In particular, the thesis begins with development of a technique using ultrasonic backscatter analyses to quantitate the early stages of aortic stenosis. Subsequent chapters utilized this methodology to quantitate aortic valve structural changes in a model and intervention study of aortic stenosis in rabbits. The last chapters are human studies designed to identify factors associated with presence of aortic sclerosis/stenosis; with particular interest in potential association of endothelial dysfunction/inflammation/platelet aggregation with abnormal aortic valve structure quantitated by ultrasonic backscatter. In Chapter 1 (Introduction) the relevant literature is reviewed. Development of ultrasonic backscatter to quantitate aortic sclerosis (Chapter 2) Aortic valve sclerosis (ASc) is detected when there is visual assessment of focal increases in echogenicity of the aortic valve most commonly assessed by echocardiography. However, there is no previously described method to quantitate degree of aortic valve structural abnormality as ASc is not associated with marked hemodynamic obstruction quantifiable by Doppler echocardiography. The current study used ultrasonic backscatter to quantitate aortic valve structural abnormality in patients assessed as having ASc based on valve appearances, compared to young healthy volunteers with normal aortic valves. The results of the study indicate: 1) that the mean levels of aortic valve backscatter in ASc patients are approximately 60% greater than in young healthy volunteers (ie aortic valve backscatter scores ≥ 16dB are not consistent with normal aortic valve structure), 2) ultrasonic backscatter scores in ASc patients are directly correlated with subjective scoring of sclerosis and with a positive trend with transvalvular pressure gradients in patients with mild-moderate aortic stenosis, and most importantly, 3) ultrasonic backscatter is a reproducible technique, with mean differences between estimates based on repeat echocardiograms of 2.3 ± 1.7 (9.1%). These results indicate that ultrasonic backscatter could be used as a quantitative measure of aortic valve structural abnormality in epidemiology and for examination of interventions. In vivo studies Development of an animal model of aortic stenosis with vitamin D2 (Chapter 3) The aim of the study was to develop an appropriate animal model for AS. The study used vitamin D2 alone at 25,000IU/4 days weekly (vit-D2) for 8 weeks to induce AS in rabbits. Results showed that: 1) rabbits in the vit-D2 group had significantly increased in transvalvular velocity and pressure gradients compared to rabbits in the control group (normal chow + drinking water); this was consistent for aortic valve ultrasonic backscatter scores; 2) aortic valve immunohistochemistry/histology showed marked calcification, neutral lipids, macrophage, and leukocyte infiltrations for rabbits in the vit- D2 group (ie consistent with histology of human AS); 3) significant elevation of asymmetric dimethylarginine (ADMA) concentrations in the vit-D2 group occurred compared to controls over the 8 weeks treatment period; the change in ADMA concentrations correlated significantly with the change in transvalvular pressure gradients for rabbits in the vit-D2 group; 4) rabbits in the vit-D2 group had significantly impaired endothelium-dependent acetylcholine-induced aortic relaxation, and this effect was completely abolished by the nitric oxide synthase inhibitor (L-NAME); 5) the addition of 0.5% cholesterol-supplemented diet to the vitamin D2 regimen did not accentuate the development of AS. Thus, treatment with vitamin D2 at 25,000IU/4 days weekly for 8 weeks significantly induced AS with similar aortic valve pathology to that of human AS; therefore, the model is suitable for use in examining potential therapeutic interventions in AS. Effects of ramipril on development of AS in rabbits (Chapter 4) Using this animal model, this study aimed to examine the effects of the angiotensinconverting enzyme inhibitor (ACEi) ramipril on development of AS. Rabbits (n=28) treated for 8 weeks were divided into 2 groups: (a) vitamin D2 alone (n=10) (normal chow + 25,000IU vitamin D2 in drinking water); (b) vitamin D2/Ramipril (n=12) (normal chow+25,000IU vitamin D2/Ramipril (0.5mg/kg) in drinking water). Six further rabbits constituted a normal reference group (no treatment was given). The results for comparisons between vitamin D2/ramipril vs vitamin D2 alone were as follows: 1) ramipril-treated rabbits had significantly less severe hemodynamic obstructions (p<0.05, for both) as assessed by transvalvular velocity, and aortic valve area; with borderline reduction in aortic valve backscatter (p=0.08); 2) ramipril significantly reduced plasma ADMA concentrations; 3) there was improvement in acetylcholine-induced aortic relaxation (p=0.056), with significant improvement in sodium nitroprusside-induced relaxation (p<0.05); 4) there was a strong inverse correlation between acetylcholineinduced aortic relaxation and aortic valve backscatter score (0<0.001), thus providing further evidence of the potential role of nitric oxide in retarding the development of AS in this model. These data provide a strong rationale for the inception of a randomized trial of ACE inhibition as a strategy for limitation of AS progression in humans. Human studies Aortic stenosis is associated with elevated plasma levels of asymmetric dimethylarginine (ADMA) concentrations in humans (Chapter 5). Given the findings that aortic stenosis induced by vitamin D2 in rabbits also caused elevation of plasma ADMA concentrations, a physiological inhibitor of nitric oxide synthase, a mediator and marker of endothelial dysfunction and an indicator of incremental cardiovascular risk. The study sought to determine whether plasma ADMA concentrations are elevated independently of pre-existing coronary risk factors in subjects with at least moderate aortic stenosis (n=42) compared to age-matched patients with normal aortic valves (n=42): as determined both by visual assessment and with aortic valve backscatter scores < 16dB. Results for this study were as follows: 1) plasma ADMA concentrations were not statistically different between the AS and non-AS group (median 0.59 vs 0.54 µmol/L, p=0.13, Mann-Whitney test) on univariate analysis; 2) backward stepwise multiple linear regression showed the presence of AS was a significant predictor of elevated ADMA concentrations (p=0.04, 95% CI =0.001, 0.072). 3) in addition, elevated plasma ADMA concentrations were also associated with history of atrial fibrillation (p=0.009, 95% CI=0.015, 0.100), and negatively associated with creatinine clearance (p=0.01, 95% CI=-0.002, 0.000), and the use of statin therapy (p=0.01, 95% CI=-0.081, -0.011). Therefore, in conclusion, this study found that AS is independently associated with elevation of ADMA concentrations, beyond that implied by “conventional” risk factors for endothelial dysfunction. The clinical status of AS as an incremental marker of cardiovascular risk may reflect ADMA-mediated endothelial dysfunction. Assessment of factors associated with ASc in a random ageing population study (Chapter 6). There have been few clinical studies of factors associated with ASc. Previous population studies have established that ASc is an independent correlate of incremental risk of coronary events. Having established that patients with AS have increased plasma ADMA concentrations (Chapter 5), it was now aimed to determine whether subjects with increased aortic valve backscatter scores (ASc) also have other markers of endothelial dysfunction/NO effects, independent of preexisting coronary risk factors. The study was designed to identify such anomalies, if they existed, on an incremental basis to other putative correlates of ASc, including coronary risk factors, renal dysfunction and vitamin D levels. Random selected subjects (n=253) aged between 51 to 77 years were evaluated. All patients underwent transthoracic echocardiography examination; aortic valve ultrasonic backscatter score (AVBS), was used to quantitate echogenicity of the aortic valve. Conventional coronary risk factors were identified on history. Integrity of NO generation/response was assessed via (i) plasma ADMA concentrations; (ii) inhibition of platelet aggregation by the NO donor sodium nitroprusside (SNP); (iii) aortic augmentation index (AIx), a measure of arterial stiffness/wave reflection. All putative correlations with AVBS were examined by univariate and stepwise multiple linear regression analyses. On the basis of echocardiographic appearances, ASc was present in 63 subjects (25.4%); mean AVBS scores was 14.9±4.6dB (SD) vs 11.2±3.9dB (SD) in the presence vs absence of ASc (p<0.001). Univariate analyses revealed that platelet responsiveness to NO was inversely correlated with AVBS (β=-0.16, p=0.02); but [ADMA] and AIx were not. On multiple linear regression, significant correlates of increased AVBS were: (i) advanced age (β=0.21, p=0.003), (ii) low body mass index (β=-0.23, p=0.001); and (iii) impaired platelet responsiveness to NO (β=-0.16, p=0.02). In Chapter 7, the implications of the overall findings in this thesis are discussed in relation to future perspective. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1309350 / Thesis(Ph.D.) -- School of Medicine, 2008

Experiments described in this thesis address the pathogenesis of aortic valve sclerosis/stenosis using a bench to bedside approach. In particular, the thesis begins with development of a technique using ultrasonic backscatter analyses to quantitate the early stages of aortic stenosis. Subsequent chapters utilized this methodology to quantitate aortic valve structural changes in a model and intervention study of aortic stenosis in rabbits. The last chapters are human studies designed to identify factors associated with presence of aortic sclerosis/stenosis; with particular interest in potential association of endothelial dysfunction/inflammation/platelet aggregation with abnormal aortic valve structure quantitated by ultrasonic backscatter. In Chapter 1 (Introduction) the relevant literature is reviewed. Development of ultrasonic backscatter to quantitate aortic sclerosis (Chapter 2) Aortic valve sclerosis (ASc) is detected when there is visual assessment of focal increases in echogenicity of the aortic valve most commonly assessed by echocardiography. However, there is no previously described method to quantitate degree of aortic valve structural abnormality as ASc is not associated with marked hemodynamic obstruction quantifiable by Doppler echocardiography. The current study used ultrasonic backscatter to quantitate aortic valve structural abnormality in patients assessed as having ASc based on valve appearances, compared to young healthy volunteers with normal aortic valves. The results of the study indicate: 1) that the mean levels of aortic valve backscatter in ASc patients are approximately 60% greater than in young healthy volunteers (ie aortic valve backscatter scores ≥ 16dB are not consistent with normal aortic valve structure), 2) ultrasonic backscatter scores in ASc patients are directly correlated with subjective scoring of sclerosis and with a positive trend with transvalvular pressure gradients in patients with mild-moderate aortic stenosis, and most importantly, 3) ultrasonic backscatter is a reproducible technique, with mean differences between estimates based on repeat echocardiograms of 2.3 ± 1.7 (9.1%). These results indicate that ultrasonic backscatter could be used as a quantitative measure of aortic valve structural abnormality in epidemiology and for examination of interventions. In vivo studies Development of an animal model of aortic stenosis with vitamin D2 (Chapter 3) The aim of the study was to develop an appropriate animal model for AS. The study used vitamin D2 alone at 25,000IU/4 days weekly (vit-D2) for 8 weeks to induce AS in rabbits. Results showed that: 1) rabbits in the vit-D2 group had significantly increased in transvalvular velocity and pressure gradients compared to rabbits in the control group (normal chow + drinking water); this was consistent for aortic valve ultrasonic backscatter scores; 2) aortic valve immunohistochemistry/histology showed marked calcification, neutral lipids, macrophage, and leukocyte infiltrations for rabbits in the vit- D2 group (ie consistent with histology of human AS); 3) significant elevation of asymmetric dimethylarginine (ADMA) concentrations in the vit-D2 group occurred compared to controls over the 8 weeks treatment period; the change in ADMA concentrations correlated significantly with the change in transvalvular pressure gradients for rabbits in the vit-D2 group; 4) rabbits in the vit-D2 group had significantly impaired endothelium-dependent acetylcholine-induced aortic relaxation, and this effect was completely abolished by the nitric oxide synthase inhibitor (L-NAME); 5) the addition of 0.5% cholesterol-supplemented diet to the vitamin D2 regimen did not accentuate the development of AS. Thus, treatment with vitamin D2 at 25,000IU/4 days weekly for 8 weeks significantly induced AS with similar aortic valve pathology to that of human AS; therefore, the model is suitable for use in examining potential therapeutic interventions in AS. Effects of ramipril on development of AS in rabbits (Chapter 4) Using this animal model, this study aimed to examine the effects of the angiotensinconverting enzyme inhibitor (ACEi) ramipril on development of AS. Rabbits (n=28) treated for 8 weeks were divided into 2 groups: (a) vitamin D2 alone (n=10) (normal chow + 25,000IU vitamin D2 in drinking water); (b) vitamin D2/Ramipril (n=12) (normal chow+25,000IU vitamin D2/Ramipril (0.5mg/kg) in drinking water). Six further rabbits constituted a normal reference group (no treatment was given). The results for comparisons between vitamin D2/ramipril vs vitamin D2 alone were as follows: 1) ramipril-treated rabbits had significantly less severe hemodynamic obstructions (p<0.05, for both) as assessed by transvalvular velocity, and aortic valve area; with borderline reduction in aortic valve backscatter (p=0.08); 2) ramipril significantly reduced plasma ADMA concentrations; 3) there was improvement in acetylcholine-induced aortic relaxation (p=0.056), with significant improvement in sodium nitroprusside-induced relaxation (p<0.05); 4) there was a strong inverse correlation between acetylcholineinduced aortic relaxation and aortic valve backscatter score (0<0.001), thus providing further evidence of the potential role of nitric oxide in retarding the development of AS in this model. These data provide a strong rationale for the inception of a randomized trial of ACE inhibition as a strategy for limitation of AS progression in humans. Human studies Aortic stenosis is associated with elevated plasma levels of asymmetric dimethylarginine (ADMA) concentrations in humans (Chapter 5). Given the findings that aortic stenosis induced by vitamin D2 in rabbits also caused elevation of plasma ADMA concentrations, a physiological inhibitor of nitric oxide synthase, a mediator and marker of endothelial dysfunction and an indicator of incremental cardiovascular risk. The study sought to determine whether plasma ADMA concentrations are elevated independently of pre-existing coronary risk factors in subjects with at least moderate aortic stenosis (n=42) compared to age-matched patients with normal aortic valves (n=42): as determined both by visual assessment and with aortic valve backscatter scores < 16dB. Results for this study were as follows: 1) plasma ADMA concentrations were not statistically different between the AS and non-AS group (median 0.59 vs 0.54 µmol/L, p=0.13, Mann-Whitney test) on univariate analysis; 2) backward stepwise multiple linear regression showed the presence of AS was a significant predictor of elevated ADMA concentrations (p=0.04, 95% CI =0.001, 0.072). 3) in addition, elevated plasma ADMA concentrations were also associated with history of atrial fibrillation (p=0.009, 95% CI=0.015, 0.100), and negatively associated with creatinine clearance (p=0.01, 95% CI=-0.002, 0.000), and the use of statin therapy (p=0.01, 95% CI=-0.081, -0.011). Therefore, in conclusion, this study found that AS is independently associated with elevation of ADMA concentrations, beyond that implied by “conventional” risk factors for endothelial dysfunction. The clinical status of AS as an incremental marker of cardiovascular risk may reflect ADMA-mediated endothelial dysfunction. Assessment of factors associated with ASc in a random ageing population study (Chapter 6). There have been few clinical studies of factors associated with ASc. Previous population studies have established that ASc is an independent correlate of incremental risk of coronary events. Having established that patients with AS have increased plasma ADMA concentrations (Chapter 5), it was now aimed to determine whether subjects with increased aortic valve backscatter scores (ASc) also have other markers of endothelial dysfunction/NO effects, independent of preexisting coronary risk factors. The study was designed to identify such anomalies, if they existed, on an incremental basis to other putative correlates of ASc, including coronary risk factors, renal dysfunction and vitamin D levels. Random selected subjects (n=253) aged between 51 to 77 years were evaluated. All patients underwent transthoracic echocardiography examination; aortic valve ultrasonic backscatter score (AVBS), was used to quantitate echogenicity of the aortic valve. Conventional coronary risk factors were identified on history. Integrity of NO generation/response was assessed via (i) plasma ADMA concentrations; (ii) inhibition of platelet aggregation by the NO donor sodium nitroprusside (SNP); (iii) aortic augmentation index (AIx), a measure of arterial stiffness/wave reflection. All putative correlations with AVBS were examined by univariate and stepwise multiple linear regression analyses. On the basis of echocardiographic appearances, ASc was present in 63 subjects (25.4%); mean AVBS scores was 14.9±4.6dB (SD) vs 11.2±3.9dB (SD) in the presence vs absence of ASc (p<0.001). Univariate analyses revealed that platelet responsiveness to NO was inversely correlated with AVBS (β=-0.16, p=0.02); but [ADMA] and AIx were not. On multiple linear regression, significant correlates of increased AVBS were: (i) advanced age (β=0.21, p=0.003), (ii) low body mass index (β=-0.23, p=0.001); and (iii) impaired platelet responsiveness to NO (β=-0.16, p=0.02). In Chapter 7, the implications of the overall findings in this thesis are discussed in relation to future perspective. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1309350 / Thesis(Ph.D.) -- School of Medicine, 2008

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

O expressivo número de brasileiros que necessitam correção anatômica da estenose valvar aórtica acentuada e que não realizam cirurgia de substituição valvar devido ao risco proibitivo justifica a necessidade de investigação, tanto da efetividade no cenário clínico real quanto dos custos impostos ao Sistema Único de Saúde e aos planos de saúde suplementar brasileiros pela incorporação do implante transcateter de valva aórtica, que tem se demonstrado efetivo mas oneroso, internacionalmente. No primeiro artigo da tese, avaliaram-se os desfechos intra-hospitalares, a sobrevida e o reembolso pela internação hospitalar de 41 pacientes com idade média de 78,7 ± 6,3 anos, estenose valvar aórtica acentuada, com recusa cirúrgica e decisão multidisciplinar por tratamento transcateter entre outubro de 2010 e outubro de 2015. Os sujeitos foram seguidos prospectivamente por um período mediano de 15,2 (4,5 – 25,6) meses e a sobrevida estimada em 1 e 2 anos foi de 73,2% e 64,1%, respectivamente. Identificou-se que hipertensão pulmonar e revascularização miocárdica cirúrgica prévia estavam independentemente associadas à menor sobrevida. O valor mediano reembolsado pelos pacientes atendidos pelo Sistema Único de Saúde foi R$ 108.634,34 (101.051,05 – 127.255,27) e R$ 115.126,77 (94.603,21 – 132.603,01) para aqueles internados por planos de saúde suplementar ou particulares, sendo o respectivo valor mediano reembolsado pela prótese valvar de R$ 82.000,00 (82.000,00 – 95.450,00) e 84.050,00 (75.000,00 – 92.400,00) Em um grupo de 585 procedimentos de troca valvar aórtica cirúrgica em indivíduos com idade ≥ 60 anos, realizados entre janeiro de 2010 e dezembro de 2015 na mesma instituição, a mortalidade intra-hospitalar estava associada à idade e foi de 5,9% naqueles com idade entre 60 e 70 anos, 10,8% entre 70 e 80 anos e de 22,2% ≥ 80 anos. O reembolso mediano foi de R$ 14.035,96 (11.956,11 – 16.644,90) para os internados pelo Sistema único de Saúde e R$ 20.273,97 (15.358.03 – 32.815,49) pelos planos de saúde suplementar ou particulares. No segundo artigo da tese, identificou-se que do total de 819 pacientes consecutivamente incluídos no Registro Brasileiro de Implante de Bioprótese Aórtica por Cateter entre janeiro de 2008 e outubro de 2015, 15 (1,8%) sofreram perfuração do ventrículo esquerdo. Os pacientes que apresentaram perfuração eram mais idosos (85,4 ± 6,3 vs. 81,5 ± 7,3 anos, p=0,038), predominantemente mulheres (80,0% vs. 50,5%, p=0,024), apresentavam maior fração de ejeção (67,3 ± 7,8% vs. 58,6 ± 15,0%, p=0,001), menor massa ventricular esquerda (203,9 ± 47,1g vs. 247,6 ± 78,7g, p=0,039) e menor altura do tronco da coronária esquerda (11,2 ± 5,4mm vs. 14,0 ± 3,3mm, p=0,034). Os preditores independentes de perfuração do ventrículo esquerdo foram idade e fração de ejeção. No terceiro artigo, descreve-se um caso de ablação septal para tratamento de miocardiopatia hipertrófica obstrutiva assimétrica para posterior implante transcateter de valva aórtica, sugerindo que esta seja uma estratégia factível quando da concomitância dessas duas condições Em conclusão, os desfechos do tratamento transcateter da estenose valvar aórtica acentuada em pacientes inoperáveis são compatíveis com aqueles do cenário idealizado dos ensaios clínicos randomizados, apesar de estarem associados a custos maiores que os anteriormente estimados por painéis de especialistas. O tratamento cirúrgico, por sua vez, apresentou mortalidade maior que aquela idealizada ou relatada como usual. A hipercinesia do ventrículo esquerdo pode favorecer o trauma determinado pelo guia metálico, posicionado em seu interior para realização do procedimento, estando a fração de ejeção independentemente associada à chance de perfuração. Ainda, a ablação septal por álcool eletiva, anterior ao implante transcateter da valva aórtica, é uma abordagem factível para pacientes com hipertrofia ventricular esquerda assimétrica obstrutiva associada à estenose valvar aórtica. / The expressive number of Brazilians who require an anatomic correction for severe aortic valve stenosis and who do not undergo valvar replacement surgery due to prohibitive risk justifies the need to investigate both the effectiveness in the real clinical scenario and the costs imposed to the Public Health System and the Supplementary Health System for the incorporation of the transcatheter aortic valve implantation, which has been shown to be effective but onerous, internationally. In the first article of the thesis, the in-hospital outcomes, long-term survival and reimbursement for 41 patients, with a mean age of 78.7 ± 6.3 years, sever aortic valve stenosis, with surgical refusal and multidisciplinary decision for transcatheter treatment, between October 2010 and October 2015 are described. Subjects were prospectively followed for a median period of 15.2 (4.5 - 25.6) months and the estimated survival at 1 and 2 years was 73.2% and 64.1%, respectively. It was identified that pulmonary hypertension and previous coronary artery bypass grafting were independently associated with lower survival. Median reimbursed values by the Public Health System was R$ 108,634.34 (101,051.05 - 127,255.27) and by supplementary health plans was R$ 115,126.77 (94,603.21 - 132,603.01). The respective median values reimbursed for the valve prosthesis was R$ 82,000.00 (82,000.00 - 95,450.00) and 84,050.00 (75,000.00 - 92,400.00) In a group of 585 surgical aortic valve replacement procedures in subjects aged ≥ 60 years, performed between January 2010 and December 2015 in the same institution, in-hospital mortality was associated with age and was 5.9% in those with age between 60 and 70 years, 10.8% between 70 and 80 years and 22.2% in ≥ 80 years. The median reimbursement was R$ 14,035.96 (11,956.11 - 16,644.90) for those hospitalized by the Public Health System and R$ 20,273.97 (15,358.03 - 32,815.49) by supplementary or private health plans. In the second article of the thesis, it was identified that of the total of 819 patients consecutively included in the Brazilian Registry of Aortic Bioprosthesis Implantation by Catheter (RIBAC) between January 2008 and October 2015, 15 (1.8%) suffered perforation of the left ventricle. Patients with perforation were older (85.4 ± 6.3 vs. 81.5 ± 7.3 years, p=0.038), predominantly women (80.0% vs. 50.5%, p=0.024), had a higher ejection fraction (67.3 ± 7.8% vs. 58.6 ± 15.0%, p=0.001), lower left ventricular mass (203.9 ± 47.1g vs. 247.6 ± 78, 7g, p=0.039) and shorter distance between the aortic annulus and the left main coronary artery ostium (11.2 ± 5.4mm vs. 14.0 ± 3.3mm, p=0.034). The independent predictors of left ventricular perforation were age and ejection fraction. In the third article, a case of septal ablation was described for the treatment of asymmetric obstructive hypertrophic cardiomyopathy for posterior transcatheter aortic valve implantation, suggesting that this is a feasible strategy when these two conditions are concomitant In conclusion, the outcomes of transcatheter treatment of severe aortic stenosis in inoperable patients are compatible with those in the ideal scenario of randomized clinical trials, although they are associated with higher costs than previously estimated by expert panels. Surgical treatment, on the other hand, presented higher mortality than that idealized or reported as usual. The left ventricle hyperkinesia may favor the trauma determined by the metallic guide, positioned inside it to perform the procedure, the ejection fraction being independently associated with the chance of perforation. Furthermore, elective alcohol septal ablation, prior to transcatheter aortic valve implantation, is a feasible approach for patients with obstructive asymmetric left ventricular hypertrophy associated with aortic valve stenosis.

Made available in DSpace on 2016-06-07T17:12:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-02. Added 1 bitstream(s) on 2016-06-07T17:16:46Z : No. of bitstreams: 1 000866188.pdf: 703355 bytes, checksum: 0b29948d0caf17093c2ef18fe5f398a8 (MD5) / A insuficiência cardíaca caracteriza-se pela diminuição da capacidade física com exacerbação precoce de fadiga e dispneia. Embora alterações intrínsecas da musculatura esquelética têm sido responsabilizadas por esses sintomas, os mecanismos envolvidos nas anormalidades musculares ainda não estão completamente esclarecidos. O estresse oxidativo miocárdico e sistêmico está aumentado na insuficiência cardíaca. Entretanto, há pouca informação sobre seu papel nas alterações da musculatura esquelética e sobre as fontes de geração de espécies reativas de oxigênio (EROs). Apesar do complexo NADPH oxidase constituir importante fonte geradora de EROs, poucos estudos avaliaram seu comportamento em músculos esqueléticos durante a insuficiência cardíaca. No miocárdio, a apocinina pode inibir o complexo NADPH oxidase e reduzir o estresse oxidativo durante agressão cardíaca. Objetivo: Avaliar os efeitos do tratamento com apocinina sobre alterações cardíacas e anormalidades fenotípicas e do estresse oxidativo do músculo sóleo de ratos com insuficiência cardíaca induzida por estenose aórtica supravalvar. Métodos: Vinte semanas após a indução da estenose aórtica, ratos Wistar foram alocados nos grupos estenose aórtica (EAo), EAo tratado com apocinina (EAo-apo) e controle (Sham). A apocinina foi administrada por oito semanas na água de beber (16 mg/kg/dia). Ecocardiograma transtorácico foi realizado antes e após o tratamento com apocinina. A atividade das enzimas antioxidantes superóxido dismutase, glutationa peroxidase e catalase e a concentração de hidroperóxido de lipídeo foram avaliadas por espectrofotometria no músculo sóleo. A concentração sérica de malonaldeído, a atividade muscular da NADPH oxidase e a geração total de EROs no músculo sóleo foram analisadas por HPLC. No sóleo, a composição das cadeias pesadas de miosina foi avaliada por eletroforese e a área seccional das fibras foi... / Heart failure is characterized by a decreased functional capacity with early fatigue and dyspnea. Although intrinsic skeletal muscle changes may be at least partially responsible for these symptoms, mechanisms involved in muscle abnormalities are not completely clear. Myocardial and systemic oxidative stress is increased during heart failure. However, there is scarce information on the sources of oxygen reactive species (ROS) and on the role of oxidative stress in inducing skeletal muscle changes. NADPH oxidase complex is an important source of ROS; only a few studies have evaluated its activity in skeletal muscles during heart failure. In myocardial, apocynin can inhibit NADPH oxidase activity and reduce oxidative stress during cardiac injury. Purpose: In this study we evaluated the effects of the antioxidant apocynin on cardiac alterations and soleus muscle oxidative stress and phenotypic characteristics in rats with supravalvar aortic stenosis-induced heart failure. Methods: Twenty weeks after inducing aortic stenosis, Wistar rats were assigned into three groups: aortic stenosis (AS), AS treated with apocynin (AS-apo, 16 mg/kg/day dissolved in drinking water for eight weeks), and control (Sham). Transthoracic echocardiogram was performed before and after apocynin treatment. Activity of the antioxidant enzymes superoxide dismutase, gluthatione peroxidase, and catalase, and lipid hydroperoxide concentration were assessed by spectrophotometry in the soleus muscle. Serum concentration of malondialdehyde and soleus muscle NADPH oxidase activity and total ROS generation were analyzed by HPLC. Soleus myosin heavy chain composition was evaluated by electrophoresis and fiber cross-sectional areas were measured in hematoxylin and eosin-stained histological sections. Statistical analysis: one-way analysis of variance complemented by Bonferroni or Mann- Whitney test. Results: Before treatment, AS and AS-apo groups presented concentric hypertrophy ...

Orientador: Marina Politi Okoshi / Coorientador: Paula Felippe Martins / Banca: Bertha Furlan Polegato / Banca:Silméia Garcia Zanati Bazan / Banca: Denise de Castro Fernandes / Banca: Fábio Rodrigues Ferreira Silva / Resumo: A insuficiência cardíaca caracteriza-se pela diminuição da capacidade física com exacerbação precoce de fadiga e dispneia. Embora alterações intrínsecas da musculatura esquelética têm sido responsabilizadas por esses sintomas, os mecanismos envolvidos nas anormalidades musculares ainda não estão completamente esclarecidos. O estresse oxidativo miocárdico e sistêmico está aumentado na insuficiência cardíaca. Entretanto, há pouca informação sobre seu papel nas alterações da musculatura esquelética e sobre as fontes de geração de espécies reativas de oxigênio (EROs). Apesar do complexo NADPH oxidase constituir importante fonte geradora de EROs, poucos estudos avaliaram seu comportamento em músculos esqueléticos durante a insuficiência cardíaca. No miocárdio, a apocinina pode inibir o complexo NADPH oxidase e reduzir o estresse oxidativo durante agressão cardíaca. Objetivo: Avaliar os efeitos do tratamento com apocinina sobre alterações cardíacas e anormalidades fenotípicas e do estresse oxidativo do músculo sóleo de ratos com insuficiência cardíaca induzida por estenose aórtica supravalvar. Métodos: Vinte semanas após a indução da estenose aórtica, ratos Wistar foram alocados nos grupos estenose aórtica (EAo), EAo tratado com apocinina (EAo-apo) e controle (Sham). A apocinina foi administrada por oito semanas na água de beber (16 mg/kg/dia). Ecocardiograma transtorácico foi realizado antes e após o tratamento com apocinina. A atividade das enzimas antioxidantes superóxido dismutase, glutationa peroxidase e catalase e a concentração de hidroperóxido de lipídeo foram avaliadas por espectrofotometria no músculo sóleo. A concentração sérica de malonaldeído, a atividade muscular da NADPH oxidase e a geração total de EROs no músculo sóleo foram analisadas por HPLC. No sóleo, a composição das cadeias pesadas de miosina foi avaliada por eletroforese e a área seccional das fibras foi... / Abstract: Heart failure is characterized by a decreased functional capacity with early fatigue and dyspnea. Although intrinsic skeletal muscle changes may be at least partially responsible for these symptoms, mechanisms involved in muscle abnormalities are not completely clear. Myocardial and systemic oxidative stress is increased during heart failure. However, there is scarce information on the sources of oxygen reactive species (ROS) and on the role of oxidative stress in inducing skeletal muscle changes. NADPH oxidase complex is an important source of ROS; only a few studies have evaluated its activity in skeletal muscles during heart failure. In myocardial, apocynin can inhibit NADPH oxidase activity and reduce oxidative stress during cardiac injury. Purpose: In this study we evaluated the effects of the antioxidant apocynin on cardiac alterations and soleus muscle oxidative stress and phenotypic characteristics in rats with supravalvar aortic stenosis-induced heart failure. Methods: Twenty weeks after inducing aortic stenosis, Wistar rats were assigned into three groups: aortic stenosis (AS), AS treated with apocynin (AS-apo, 16 mg/kg/day dissolved in drinking water for eight weeks), and control (Sham). Transthoracic echocardiogram was performed before and after apocynin treatment. Activity of the antioxidant enzymes superoxide dismutase, gluthatione peroxidase, and catalase, and lipid hydroperoxide concentration were assessed by spectrophotometry in the soleus muscle. Serum concentration of malondialdehyde and soleus muscle NADPH oxidase activity and total ROS generation were analyzed by HPLC. Soleus myosin heavy chain composition was evaluated by electrophoresis and fiber cross-sectional areas were measured in hematoxylin and eosin-stained histological sections. Statistical analysis: one-way analysis of variance complemented by Bonferroni or Mann- Whitney test. Results: Before treatment, AS and AS-apo groups presented concentric hypertrophy ... / Doutor