960 resultados para Electromechanical Heart Model


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Aims Trials of disease management programmes (DMP) in heart failure (HF) have shown controversial results regarding quality of life. We hypothesized that a DMP applied over the long-term could produce different effects on each of the quality-of-life components. Methods and results We extended the prospective, randomized REMADHE Trial, which studied a DMP in HF patients. We analysed changes in Minnesota Living with Heart Failure Questionnaire components in 412 patients, 60.5% male, age 50.2 +/- 11.4 years, left ventricular ejection fraction 34.7 +/- 10.5%. During a mean follow-up of 3.6 +/- 2.2 years, 6.3% of patients underwent heart transplantation and 31.8% died. Global quality-of-life scores improved in the DMP intervention group, compared with controls, respectively: 57.5 +/- 3.1 vs. 52.6 +/- 4.3 at baseline, 32.7 +/- 3.9 vs. 40.2 +/- 6.3 at 6 months, 31.9 +/- 4.3 vs. 41.5 +/- 7.4 at 12 months, 26.8 +/- 3.1 vs. 47.0 +/- 5.3 at the final assessment; P<0.01. Similarly, the physical component (23.7 +/- 1.4 vs. 21.1 +/- 2.2 at baseline, 16.2 +/- 2.9 vs. 18.0 +/- 3.3 at 6 months, 17.3 +/- 2.9 vs. 23.1 +/- 5.7 at 12 months, 11.4 +/- 1.6 vs. 19.9 +/- 2.4 final; P<0.01), the emotional component (13.2 +/- 1.0 vs. 12.1 +/- 1.4 at baseline, 11.7 +/- 2.7 vs. 12.3 +/- 3.1 at 6 months, 12.4 +/- 2.9 vs. 16.8 +/- 5.9 at 12 months, 6.7 +/- 1.0 vs. 10.6 +/- 1.4 final; P<0.01) and the additional questions (20.8 +/- 1.2 vs. 19.3 +/- 1.8 at baseline, 14.3 +/- 2.7 vs. 17.3 +/- 3.1 at 6 months, 12.4 +/- 2.9 vs. 21.0 +/- 5.5 at 12 months, 6.7 +/- 1.4 vs. 17.3 +/- 2.2 final; P<0.01) were better (lower) in the intervention group. The emotional component improved earlier than the others. Post-randomization quality of life was not associated with events. Conclusion Components of the quality-of-life assessment responded differently to DMP. These results indicate the need for individualized DMP strategies in patients with HF. Trial registration information www.clincaltrials.gov NCT00505050-REMADHE.

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Background: The aim of this study was to evaluate the degree of tricuspid valve insufficiency after orthotopic cardiac transplantation with bicaval anastomosis and prophylactic donor heart annuloplasty. Methods: At present, our cardiac transplantation experience includes 478 cases. After January 2002, we included 30 consecutive patients in this study who had undergone orthotopic cardiac transplantation and survived >6 months. The patients were divided into 2 groups: group I, 15 patients who underwent transplantation with prophylactic tricuspid annuloplasty on the donor heart with the De Vega technique; and group II, 15 patients who underwent transplantation without this procedure. Their preoperative clinical characteristics were the same. During the late postoperative follow-up, the degree of tricuspid insufficiency was evaluated by transthoracic Doppler echocardiography and assessed according to the Simpson scale: 0, absent; 1, mild; 2, moderate; and 3, severe. Hemodynamic parameters were evaluated invasively by means of a Swan-Ganz catheter during routine endomyocardial biopsies. Results: The mean follow-up time was 26.9 +/- 5.4 months (range, 12-36 months). In group I, 1 patient (6.6%) died from infection in the 18th month after the operation; the death was not related to the annuloplasty. In group II, 1 death (6.6%) occurred after 10 months because of rejection (P > .05). After the 24-month follow-up, the mean degree of tricuspid insufficiency was 0.4 +/- 0.5 in group I and 1.7 +/- 0.9 in group II (P < .05). Similarly, the 2 groups were significantly different with respect to the right atrium pressure, which was higher in group II. Conclusions: Prophylactic tricuspid annuloplasty on the donor heart was able to reduce significantly the degree of valvular insufficiency, even in cardiac transplantation with bicaval anastomosis; however, it did not modify significantly the hemodynamic performance of the allograft during the investigation period. It is very important to extend the observation period and casuistics to verify other benefits that this technique may offer.

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Background: Worsening in clinical and cardiac status has been noted after chronic right ventricular pacing, but it is uncertain whether atriobiventricular (BiVP) is preferable to atrio-right ventricular pacing (RVP). Conventional versus Multisite Pacing for BradyArrhythmia Therapy study (COMBAT) sought to compare BiVP versus RVP in patients with symptomatic heart failure (HF) and atrioventricular (AV) block. Methods and Results: COMBAT is a prospective multicenter randomized double blind crossover study. Patients with New York Heart Association functional class (FC) II-IV, left ventricular ejection fraction (LVEF) <40%, and AV block as an indication for pacing were enrolled. All patients underwent biventricular system implantation and then were randomized to receive successively (group A) RVP-BiVP-RVP, or (group B) BiVP-RVP-BiVP. At the end of each 3-month crossover period, patients were evaluated according to Quality of Life (QoL), FC, echocardiographic parameters, 6-Minute Walk Test (6MWT), and peak oxygen consumption (VO(2max)). Sixty patients were enrolled, and the mean follow-up period was 17.5 +/- 10.7 months. There were significant improvements in QoL, FC, LVEF, and left ventricular end-systolic volume with BiVP compared with RVP. The effects of pacing mode on 6MWT and VO(2max) were not significantly different. Death occurred more frequently with RVP. Conclusion: In patients with systolic HF and AV block requiring permanent ventricular pacing, BiVP is superior to RVP and should be considered the preferred pacing mode. (J Cardiac Fail 2010;16:293-300)

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Background: Significant hemodynamic changes, including preload and afterload modifications, occur during the transition from the fetal to the neonatal environment. The ductus arteriosus closes, pulmonary vascular resistance decreases, and pulmonary blood flow increases. Strain rate (SR) and strain (e) have been proposed as ultrasound indices for quantifying regional wall deformation. This study was designed to determine if these indices can detect variations in regional deformation between early and late neonatal periods. Methods: Data were obtained from 30 healthy neonates (15 male). The initial study was performed at a mean age of 20.1614 hours (exam 1) and the second at 31.962.9 days (exam 2). Apical and parasternal views were used to quantify regional left ventricular (LV) and right ventricular (RV) longitudinal and radial SR and e, and systolic, early, and late diastolic values were calculated from these curves. A paired-samples t test was performed comparing the two groups. Results: Compared with exam 1, LV radial deformation showed significant reductions in peak systolic e in the basal and mid segments (51615% vs 4669%, P < .01). LV longitudinal deformation behaved similarly, showing significant peak systolic e reductions in all measured segments. Systolic SR showed reductions only in the basal and apical segments of the lateral wall and in the mid portion of the inferior wall (-1.9 +/- 0.5 vs -1.7 +/- 0.3 s(-1) and -1.9 +/- 0.4 vs -1.7 +/- 0.2 s(-1), respectively, P = .03). RV longitudinal free and inferior wall systolic SR and e values were significantly higher in exam 2. Conclusions: LV peak systolic e decreases in exam 2 were possibly due to afterload increase and preload decrease. The lower RV initial deformation indices could be attributed to increased afterload caused by physiologic pulmonary hypertension or immature RV contractile properties. SR seemed to be a more robust index than e and less influenced by preload and afterload hemodynamic alteration. (J Am Soc Echocardiogr 2010;23:294-300.)

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Background: Physical activity (PA) has proven benefits in the primary prevention of heart diseases such as heart failure (HF). Although it is well known, HF PA habits and physicians` advice have been poorly described. The aim of this study was to investigate if physicians were advising HF patients to exercise and to quantify patients` exercise profiles in a complex cardiology hospital. Methods: All 131 HF patients (80 male, average age 53 +/- 10 years, NYHA class I-V, left ventricular ejection fraction 35 +/- 11%, 35 ischemic, 35 idiopatic , 32 hypertensive and 29 with Chagas disease) went to the hospital for a HF routine check-up. On this occasion, after seeing the physician, we asked the patients if the physician had advised them about PA. Then, we asked them to fill in the international physical activity questionnaire (IPQA) Short Form to classify their PA level. Results: Our data showed a significant difference between patients who had received any kind of PA advice from physicians (36%) and those who had not (64%, p<0.0001). Using the IPAQ criteria, of the 36% of patients who had received advice, 12.4% were classified as low and 23.6% as moderate. Of the 64% of patients who did not receive advice, 26.8% were classified as lowand 37.2% as moderate. Etiology (except Chagas), functional class, ejection fraction, sex and age did not influence the PA profile. Conclusions: Physicians at a tertiary cardiology hospital were not giving patients satisfactory advice as to PA. Our data supports the need to strengthen exercise encouragement by physicians and for complementary studies on this area. (Cardiol J 2010; 17, 2: 143-148)

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Background: Cardiac development is a complex and multifactorial biological process. Heterozygous mutations in the transcription factor NKX2.5 are between the first evidence of a genetic cause for congenital heart defects in human beings. In this study, we evaluated the presence and frequency of mutations in the NKX2.5 gene on 159 unrelated patients with a diverse range of non-syndromic congenital heart defects (conotruncal anomalies, septal defects, left-sided lesions, right-sided lesions, patent ductus arteriosus and Ebstein`s anomaly). Methods: The coding region of the NKX2.5 locus was amplified by polymerase chain reaction and mutational analysis was performed using denaturing high performance liquid chromatography (DHPLC) and DNA sequencing. Results: We identified two distinct mutations in the NKX2.5 coding region among the 159 (1.26%) individuals evaluated. An Arg25Cys mutation was identified in a patient with Tetralogy of Fallot. The second mutation found was an Ala42Pro in a patient with Ebstein`s anomaly. Conclusions: The association of NKX2.5 mutations is present in a small percentage of patients with non-syndromic congenital heart defects and may explain only a few cases of the disease. Screening strategies considering the identification of germ-line molecular defects in congenital heart disease are still unwarranted and should consider other genes besides NKX2.5. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

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Exercise training has been shown to be effective in improving exercise capacity and quality of life in patients with heart failure and left ventricular (LV) systolic dysfunction. Real-time myocardial contrast echocardiography (RTMCE) is a new technique that allows quantitative analysis of myocardial blood flow (MBF). The aim of this study was to determine the effects of exercise training on MBF in patients with LV dysfunction. We studied 23 patients with LV dysfunction who underwent RTMCE and cardiopulmonary exercise testing at baseline and 4 months after medical treatment (control group, n = 10) or medical treatment plus exercise training (trained group, n = 13). Replenishment velocity (0) and MBF reserves were derived from quantitative RTMCE. The 4-month exercise training consisted of 3 60-minute exercise sessions/week at an intensity corresponding to anaerobic threshold, 10% below the respiratory compensation point. Aerobic exercise training did not change LV diameters, volumes, or ejection fraction. At baseline, no difference was observed in MBF reserve between the control and trained groups (1.89, 1.67 to 1.98, vs 1.81, 1.28 to 2.38, p = 0.38). Four-month exercise training resulted in a significant increase in beta reserve from 1.72 (1.45 to 1.48) to 2.20 (1.69 to 2.77, p <0.001) and an MBF reserve from 1.81 (1.28 to 2.38) to 3.05 (2.07 to 3.93, p <0.001). In the control group, 13 reserve decreased from 1.51 (1.10 to 1.85) to 1.46 (1.14 to 2.33, p = 0.03) and MBF reserve from 1.89 (1.67 to 1.98) to 1.55 (1.11 to 2.27, p <0.001). Peak oxygen consumption increased by 13.8% after 4 months of exercise training and decreased by 1.9% in the control group. In conclusion, exercise training resulted in significant improvement of MBF reserve in patients with heart failure and LV dysfunction. (C) 2010 Elsevier Inc. All rights reserved. (Am J Cardiol 2010;105:243-248)

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Background-Peculiar aspects of Chagas cardiomyopathy raise concerns about efficacy and safety of sympathetic blockade. We studied the influence of beta-blockers in patients with Chagas cardiomyopathy. Methods and Results-We examined REMADHE trial and grouped patients according to etiology (Chagas versus non-Chagas) and beta-blocker therapy. Primary end point was all-cause mortality or heart transplantation. Altogether 456 patients were studied; 27 (5.9%) were submitted to heart transplantation and 202 (44.3%) died. Chagas etiology was present in 68 (14.9%) patients; they had lower body mass index (24.1+/-4.1 versus 26.3+/-5.1, P=0.001), smaller end-diastolic left ventricle diameter (6.7+/-1.0 mm versus 7.0+/-0.9 mm, P=0.001), smaller proportion of beta-blocker therapy (35.8% versus 68%, P<0.001), and higher proportion of spironolactone therapy (74.6% versus 57.8%, P=0.003). Twenty-four (35.8%) patients with Chagas disease were under beta-blocker therapy and had lower serum sodium (136.6+/-3.1 versus 138.4+/-3.1 mEqs, P=0.05) and lower body mass index (22.5+/-3.3 versus 24.9+/-4.3, P=0.03) compared with those who received beta-blockers. Survival was lower in patients with Chagas heart disease as compared with other etiologies. When only patients under beta-blockers were considered, the survival of patients with Chagas disease was similar to that of other etiologies. The survival of patients with beta-blockers was higher than that of patients without beta-blockers. In Cox regression model, left ventricle end-diastolic diameter (hazard ratio, 1.78; CI, 1.15 to 2.76; P=0.009) and beta-blockers (hazard ratio, 0.37; CI, 0.14 to 0.97; P=0.044) were associated with better survival. Conclusions-Our study suggests that beta-blockers may have beneficial effects on survival of patients with heart failure and Chagas heart disease and warrants further investigation in a prospective, randomized trial.

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Aerobic exercise training leads to a physiological, nonpathological left ventricular hypertrophy; however, the underlying biochemical and molecular mechanisms of physiological left ventricular hypertrophy are unknown. The role of microRNAs regulating the classic and the novel cardiac renin-angiotensin (Ang) system was studied in trained rats assigned to 3 groups: (1) sedentary; (2) swimming trained with protocol 1 (T1, moderate-volume training); and (3) protocol 2 (T2, high-volume training). Cardiac Ang I levels, Ang-converting enzyme (ACE) activity, and protein expression, as well as Ang II levels, were lower in T1 and T2; however, Ang II type 1 receptor mRNA levels (69% in T1 and 99% in T2) and protein expression (240% in T1 and 300% in T2) increased after training. Ang II type 2 receptor mRNA levels (220%) and protein expression (332%) were shown to be increased in T2. In addition, T1 and T2 were shown to increase ACE2 activity and protein expression and Ang (1-7) levels in the heart. Exercise increased microRNA-27a and 27b, targeting ACE and decreasing microRNA-143 targeting ACE2 in the heart. Left ventricular hypertrophy induced by aerobic training involves microRNA regulation and an increase in cardiac Ang II type 1 receptor without the participation of Ang II. Parallel to this, an increase in ACE2, Ang (1-7), and Ang II type 2 receptor in the heart by exercise suggests that this nonclassic cardiac renin-angiotensin system counteracts the classic cardiac renin-angiotensin system. These findings are consistent with a model in which exercise may induce left ventricular hypertrophy, at least in part, altering the expression of specific microRNAs targeting renin-angiotensin system genes. Together these effects might provide the additional aerobic capacity required by the exercised heart. (Hypertension. 2011;58:182-189.).

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In recent years, beta-blocker therapy has become a primary pharmacologic intervention in patients with heart failure by blocking the sympathetic activity. To compare the exercise training`s sympathetic blockade in healthy subjects (athletes) and the carvedilol`s sympathetic blockade in sedentary heart failure patients by the evaluation of the heart rate dynamic during an exercise test. A total of 26 optimized and 49 nonoptimized heart failure patients in a stable condition (for, at least, 3 months), 15 healthy athletes and 17 sedentary healthy subjects were recruited to perform a cardiopulmonary exercise test. The heart rate dynamic (rest, reserve, peak and the peak heart rate in relation to the maximum predicted for age) was analyzed and compared between the four groups. The heart rate reserve was the same between optimized (48 +/- 15) and nonoptimized (49 +/- 18) heart failure patients (P < 0.0001). The athletes (188 +/- 9) showed a larger heart rate reserve compared to sedentary healthy subjects (92 +/- 10, P < 0.0001). Athletes and healthy sedentary reached the maximum age-predicted heart ratefor their age, but none of the heart failure patients did. The carvedilol`s sympathetic blockade occurred during the rest and during the peak effort in the same proportion, but the exercise training`s sympathetic blockade in healthy subjects occurred mainly in the rest.

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We compared the effects of exercise training on neurovascular control and functional capacity in men and women with chronic heart failure (HF). Forty consecutive HF outpatients from the Heart Institute, University of Sao Paulo, Brazil were divided into the following four groups matched by age: men exercise-trained (n = 12), men untrained (n = 10), women exercise-trained (n = 9), women untrained (n = 9). Maximal exercise capacity was determined from a maximal progressive exercise test on a cycle ergometer. Forearm blood flow was measured by venous occlusion plethysmography. Muscle sympathetic nerve activity (MSNA) was recorded directly using the technique of microneurography. There were no differences between groups in any baseline parameters. Exercise training produced a similar reduction in resting MSNA (P = 0.000002) and forearm vascular resistance (P = 0.0003), in men and women with HF. Peak VO(2) was similarly increased in men and women with HF (P = 0.0003) and VE/VCO(2) slope was significantly decreased in men and women with HF (P = 0.0007). There were no significant changes in left-ventricular ejection fraction in men and women with HF. The benefits of exercise training on neurovascular control and functional capacity in patients with HF are independent of gender.

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Background-The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial in 2368 patients with stable ischemic heart disease assigned before randomization to percutaneous coronary intervention or coronary artery bypass grafting strata reported similar 5-year all-cause mortality rates with insulin sensitization versus insulin provision therapy and with a strategy of prompt initial coronary revascularization and intensive medical therapy or intensive medical therapy alone with revascularization reserved for clinical indication(s). In this report, we examine the predefined secondary end points of cardiac death and myocardial infarction (MI). Methods and Results-Outcome data were analyzed by intention to treat; the Kaplan-Meier method was used to assess 5-year event rates. Nominal P values are presented. During an average 5.3-year follow-up, there were 316 deaths (43% were attributed to cardiac causes) and 279 first MI events. Five-year cardiac mortality did not differ between revascularization plus intensive medical therapy (5.9%) and intensive medical therapy alone groups (5.7%; P = 0.38) or between insulin sensitization (5.7%) and insulin provision therapy (6%; P = 0.76). In the coronary artery bypass grafting stratum (n = 763), MI events were significantly less frequent in revascularization plus intensive medical therapy versus intensive medical therapy alone groups (10.0% versus 17.6%; P = 0.003), and the composite end points of all-cause death or MI (21.1% versus 29.2%; P = 0.010) and cardiac death or MI (P = 0.03) were also less frequent. Reduction in MI (P = 0.001) and cardiac death/MI (P = 0.002) was significant only in the insulin sensitization group. Conclusions-In many patients with type 2 diabetes mellitus and stable ischemic coronary disease in whom angina symptoms are controlled, similar to those enrolled in the percutaneous coronary intervention stratum, intensive medical therapy alone should be the first-line strategy. In patients with more extensive coronary disease, similar to those enrolled in the coronary artery bypass grafting stratum, prompt coronary artery bypass grafting, in the absence of contraindications, intensive medical therapy, and an insulin sensitization strategy appears to be a preferred therapeutic strategy to reduce the incidence of MI. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00006305. (Circulation. 2009;120:2529-2540.)

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(ECHOCARDIOGRAPHY, Volume 26, September 2009).

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Background: A previous study associated CD34(+) levels with NYHA functional class in heart failure patients. The aim of this study was to correlate CD34(+) levels to exercise capacity, functional class, quality of life and norepinephrine in heart failure patients. Methods: Twenty three sedentary patients (52 +/- 7 years, 78% male) answered the Minnesota Living with Heart Failure Questionnaire and rested for 20 minutes before an investigator collect a blood sample. After this, patients performed a cardiopulmonary exercise test to determine the heart rate at anaerobic and ventilatory threshold and oxygen consumption at peak effort, at anaerobic and ventilatory threshold. One other blood sample was collected during the peak effort to investigate the norepinephrine and CD34(+) levels. Results: Rest percentage of CD34(+) did not show correlation with: left ventricle ejection fraction (r = 0.03, p = 0.888), peakVO(2) (r = 0.32, p = 0.13), VO(2) at anaerobic threshold (VO(2)AT) (r = 0.03, p = 0.86), VO(2) at ventilatory threshold (VO(2)VT) (r = 0.36, p = 0.08), NYHA functional class (r = -0.2, p = 0.35), quality of life (Minnesota) (r = -0.17, p = 0.42). CD34(+) did not show correlation, either, with: peak VO(2) (r = 0.38, p = 0.06), VO(2)AT (r = 0.09, p = 0.65), VO(2)VT (r = 0.43, p = 0.4), NYHA functional class (r = -0.13, p = 0.54), quality of life (r = 0.00, p = 0.99). Conclusions: CD34(+) levels did not correlate with exercise capacity, functional class, quality of life and norepinephrine. Percentage of CD34(+) levels did not increase during the cardiopulmonary exercise test in heart failure patients. (Cardiol J 2009; 16, 5: 426-431)

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A continuum model for regular block structures is derived by replacing the difference quotients of the discrete equations by corresponding differential quotients. The homogenization procedure leads to an anisotropic Cosserat Continuum. For elastic block interactions the dispersion relations of the discrete and the continuous models are derived and compared. Yield criteria for block tilting and sliding are formulated. An extension of the theory for large deformation is proposed. (C) 1997 by John Wiley & Sons, Ltd.