Cardiac resynchronization therapy (CRT) is an established therapy for patients with advanced congestive heart failure and prolonged QRS duration, aiming at correcting dyssynchrony in the left ventricle (LV). Apart from the beneficial effects on cardiac function and LV reverse remodeling, reduction in functional MR has been observed by Doppler echocardiography after CRT. On the other hand, functional mitral regurgitation (MR) in fact varies over the cardiac cycle that a biphasic pattern has been reported, i.e. early- and late-systolic peaks with a mid-systolic decrease in regurgitant flow. Nevertheless, it remains to be explored whether (1) the improvement of MR leads to a greater extent of LV reverse remodeling; (2) the different components (i.e. early- and late-systolic) of MR improve and their predictors if any. / Despite comparable ejection fraction, higher degree of functional MR was associated with further impairment in short-axis myocardial deformation (circumferential and radial), but not with long-axis myocardial deformation. The degree of LV basal rotation was also lower in the MR patient group. Furthermore, the decrease in myocardial deformation was associated with greater extent of LV remodeling. / In conclusion, LV global mechanical dyssynchrony play a role in determining the severity of functional MR in addition to mitral leaflet tenting in patients with LV systolic dysfunction. Functional MR is associated with further impairment of myocardial deformation, but with differential change in individual component of myocardial deformation. CRT reduces functional MR in both early- and late-systolic phases, by way of improvement in LV remodeling, LV dyssynchrony and mitral leaflet tenting. Meanwhile, the improvement of MR contributes to LV reverse remodeling after CRT. (Abstract shortened by UMI.) / The improvement of functional MR was an independent predictor of LV reverse remodeling after CRT. The extent of LV reverse remodeling (reduction of LV end-systolic volume) was greatest in patients with improvement of MR, followed by those with "mild or no" MR at baseline, and was least in those without improvement of MR. CRT reduced functional MR by reducing both its early- and late-systolic components in heart failure patients. The reductions in LV end-systolic volume and dyssynchrony were related to the improvement of early-systolic MR, while the improvement of late-systolic MR was attributable to the reductions in mitral leaflet tenting and LV dyssynchrony. / The main findings were as follows: LV global systolic dyssynchrony served as an independent predictor for the presence of significant functional MR in patients with LV systolic dysfunction. Although mitral valvular tenting area was the most powerful predictor, LV global systolic dyssynchrony added incremental value to mitral valve tenting area in predicting the presence of significant functional MR. / We performed echocardiography with TDI and 2DSTE in 147 patients of both ischemic and non-ischemic etiologies with LV systolic dysfunction (defined as LV ejection fraction <50%) and 45 normal controls. MR severity, displacement of papillary muscle, mitral annular dilation and dysfunction, mitral leaflet tenting, LV remodeling and function were assessed by 2D and Doppler echocardiography. LV mechanical dyssynchrony indices were derived from TDI velocity. Myocardial strain (i.e. amount of deformation) in longitudinal, circumferential and radial directions and torsion (opposite rotational movement between apex and base of the heart) were measured by 2DTSE. / Liang, Yujia. / "October 2009." / Adviser: Cheuk man Yu. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 169-193). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Thesis (Ph. D.)--University of New South Wales, 2002.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [127]-138).

The projects of this thesis examine the complex interaction between isotonic exercise, functional capacity, exercise-induced myocardial ischaemia, severity of regurgitation and left ventricular function in patients with significant chronic mitral regurgitation. The concept of left ventricular contractile reserve, i.e. the ability of the left ventricle to increase its contractility and decrease its end systolic volume with isotonic exercise, is explored. In patients with chronic isolated mitral regurgitation without coronary disease, isotonic exercise was associated with a slight decrease in left ventricular end diastolic volume but a marked decrease in end systolic volume, resulting in a significant increase in the stroke volume and ejection fraction. Early after uncomplicated mitral valve repair surgery, there was a significant decrease in the left ventricular ejection fraction with a proportion of the patients developing left ventricular dysfunction despite a normal pre-operative ejection fraction. When different pre-operative echocardiographic indices of left ventricular function were evaluated for their ability to predict left ventricular function after mitral valve repair, the exercise indices were found to be superior to resting indices. Left ventricular end systolic volume immediately after exercise was found to be the best predictor. The optimal cut-off was at 25 ml/m2, which had a sensitivity and specificity of 83% in predicting early post-operative left ventricular dysfunction. Exercise indices appeared to be superior to resting indices in identifying patients with persistent left ventricular dysfunction &lt1 year after mitral valve repair. The concept of contractile reserve was further examined by estimating the left ventricular stroke work from simplified pressure-volume loops, which were constructed from non-invasively obtained parameters with geometric assumptions. Left ventricular stroke work immediately after exercise, but not at rest, was found to be significantly lower in patients with latent left ventricular dysfunction. Patients without latent ventricular dysfunction had similar increases in stroke work with exercise compared with healthy normal subjects. The ability of the left ventricle to increase its stroke work with exercise, a measure of the contractile reserve, was correlated with the left ventricular ejection fraction after mitral valve repair. A numerical model was constructed using the clinical data as input parameters. The results from the numerical model were similar to that obtained from the clinical study, testifying that the observation made in the clinical study was valid and independent of the geometric assumptions made in constructing the simplified pressure-volume loops. Left ventricular pressure-volume loops under different loading conditions were plotted from simultaneously measured left ventricular pressure and volume to measure the left ventricular end systolic elastance (Ees) and preload recruitable stroke work relationship (MSW). Despite normal or near normal haemodynamics at rest, a significant proportion of the study patients were found to have impaired left ventricular contractility, as measured by Ees, consistent with a state of latent left ventricular dysfunction. Exercise indices of left ventricular function were better correlated with Ees and MSW than resting indices. There were highly significant inverse relationships between end systolic volume index immediately after exercise and Ees and MSW. Moreover, there was a significant powered relationship between MSW and exercise left ventricular ejection fraction. There was no such relationship between Ees or MSW and any of the resting echocardiographic indices of left ventricular function. Furthermore, the optimal diagnostic cut-off level of end systolic volume index after exercise at 25 ml/m2 accurately identified those with impaired left ventricular contractility as defined by an Ees of &gt 2 mmHg/ml. In patients with chronic organic mitral regurgitation with ejection fraction of &lt 50%, objectively measured functional capacity, VO2max, was correlated with exercise cardiac output, patient age and gender but not to the severity of the mitral regurgitation or the resting left ventricular function. The VO2max of these patients were significantly lower than that of age and gender-matched healthy controls despite these patients' relative lack of subjective symptoms. There were significant individual variations in the response of the severity of the mitral regurgitation to isotonic exercise. Patients whose regurgitant stroke volume increased had a lower exercise cardiac output than those whose regurgitant stroke volume decreased. Such variability was also seen with the response of the left ventricular function to exercise. Patients whose left ventricular end systolic volume increased with exercise, i.e. patients with a limited contractile reserve, had a lower exercise cardiac output and lower VO2max than those whose end systolic volume decreased with exercise. The determinants of exercise capacity were then examined in patients with functional mitral regurgitation and left ventricular dysfunction. VO2max of these patients was correlated with exercise cardiac output and exercise left ventricular ejection fraction, a situation similar to that seen in patients with organic mitral regurgitation and normal left ventricular function. Furthermore, indices of left ventricular systolic function at rest and pulsed wave Doppler indices of diastolic function showed no significant correlations with VO2max. The determinants of VO2max remained unchanged in these patients after four weeks of supervised exercise training. The four weeks of exercise training resulted in a significant decrease in left ventricular end systolic volume, a trend towards an increase in left ventricular ejection fraction and some restoration of the contractile reserve. The total exercise time almost doubled. However, this dramatic improvement in total exercise time was accompanied only by non-significant increases in VO2max and left ventricular ejection fraction. Therefore, the benefits of exercise training in these patients may involve more than just central mechanisms. Exercise induced myocardial ischaemia may also contribute to a limited left ventricular contractile reserve in patients with mitral regurgitation. Electrocardiographic changes at rest are commonly seen in patients with mitral regurgitation due to mitral valve prolapse. These resting electrocardiographic changes make exercise electrocardiography uninterpretable for exercise-induced ischaemia. Exercise electrocardiographic changes are also commonly encountered in these patients despite the absence of coronary artery disease and a normal resting electrocardiogram, making exercise electrocardiography unreliable as a non-invasive screening test for coronary artery disease. In these patients, exercise echocardiography was slightly more sensitive but significantly more specific in diagnosing significant coronary artery disease. The overall accuracy and the positive predictive value were significantly higher for exercise echocardiography than for exercise electrocardiography. The &quotcost-effectiveness&quot of different diagnostic strategies for coronary artery disease in patients with mitral valve prolapse was examined based on the results of the clinical study. Strategies involving exercise electrocardiography as part of the screening test were costly and were associated with a high false negative rate. Strategies involving exercise echocardiography were more accurate and less costly but the initial costs of exercise echocardiography for all patients meant that the overall costs were still considerable. Assessing the pre-test probability of coronary artery disease in these patients and using exercise echocardiography as the initial test for patients with at least a moderate pre-test probability of coronary artery disease seemed to result in the best compromise between cost and effectiveness. The studies of this thesis have shown that a limited cardiac contractile reserve is a sign of latent ventricular dysfunction in patients with chronic mitral regurgitation. The presence of a limited contractile reserve can be used to predict left ventricular dysfunction after mitral valve repair. The concept of a limited contractile reserve is further supported by the finding of a limited increase in left ventricular stroke work with exercise from a theoretical as well as a numerical model of left ventricular pressure-volume loops. Exercise echocardiographic indices show better correlations to invasively measured Ees and MSW than resting indices. VO2max in these patients is determined more by their ability to increase their forward cardiac output with exercise and not by the regurgitant volumes. Exercise training in patients with left ventricular dysfunction and functional mitral regurgitation results in some restoration of contractile reserve. Exercise echocardiography is also a reliable and cost-effective test in the non-invasive screening for coronary artery disease in these patients. Based on the results of the studies in the thesis, one can incorporate exercise echocardiography as one of the important assessment tools in the management of patients with significant mitral regurgitation as it allows measurement of left ventricular volumes and assessment of contractile reserve. Further studies are needed to examine whether a policy of monitoring of contractile reserve in these patients to guide therapy and surgical referral will result in a better preservation of long term left ventricular function, an improvement in functional capacity and patient outcome.

No description available.

No description available.

Thesis (M.S.)--East Carolina University, 2009. / Presented to the faculty of the Department of Exercise and Sport Science. Advisor: Timothy P. Gavin. Title from PDF t.p. (viewed May 5, 2010). Includes bibliographical references.

The clinical features in six patients with mitral insufficiency due to chordae tendineae have been. The patients in whom the etiology was not known did not become symptomatic till they were past 40, although a murmur had been present for several years. Pulmonary edema or paroxysmal nocturnal dyspnea were the initial symptoms in a number of these patients, preceding the more usual shortness of breath with exertion. The auscultatory and phonocardiographic features are specific. On fluoroscopy readily recognizable paradoxical pulsation of the left atrium was present in some of them. At cardiac catheterization a tall left atrial “v” wave with peak pressure as high as or higher than the peak pressure in the pulmonary artery was constantly found. In a patient with mitral insufficiency where the murmur is harsh and accompanied by a thrill in the fourth intercostal space near the left sternal border and in whom an ejection type systolic murmur is heard unaccompanied by the slow rising pulse of aortic stenosis, the possibility of mitral insufficiency due to ruptured chordae tendineae should be considered.

Submitted by Fabíola Silva (fabiola.silva@famerp.br) on 2016-06-27T14:52:30Z No. of bitstreams: 1 marcelofelipekozak_dissert.pdf: 986000 bytes, checksum: 7f262464a429e4df84692f32c1e38c0d (MD5) / Made available in DSpace on 2016-06-27T14:52:30Z (GMT). No. of bitstreams: 1 marcelofelipekozak_dissert.pdf: 986000 bytes, checksum: 7f262464a429e4df84692f32c1e38c0d (MD5) Previous issue date: 2011-05-27 / Introduction: One of the most often and important complications after surgical treatment of atrioventricular septal defects is the left atrioventricular valve insufficiency. So, this study was conducted to identify risk factors for moderate or severe left atrioventricular valve regurgitation within 30 days of surgical repair of atrioventricular septal defects at our center. Methods: This was a retrospective study in which we evaluated the results of 104 consecutive patients that were operated on at our practice between 2002 and 2010. The following associated factors were considered: age, weight, Down syndrome, grade of preoperative atrioventricular valve regurgitation, abnormalities on the atrioventricular valve and the use of annuloplasty. Patients were separated in two groups according to type of AVSD: group I (complete) and group II (incomplete – partial and transitional). Characteristics of the 53 patients of the group I: the median patient age at the time of repair was 6.7 months; the median weight was 5.3 Kg; 86.8% had Down syndrome; at the time of preoperative evaluation, there were 26 cases with moderate or severe atrioventricular valve regurgitation (49.1%); annuloplasty was perfored in 34%; abnormalities on the valve were found in 11.3% of the cases. Characteristics of the 51 patients of the group II: The median patient age at the time of repair was 4.1 years; the median weight was 13.4 Kg; 37.2% had Down syndrome; at the time of preoperative evaluation, there were 23 cases with moderate or grater LAVVR (45.1%); abnormalities on the AV valve were found in 17.6% of the cases; annuloplasty was performed in 21.6% of the patients. Results: Group I - At the time of post-operative evaluation, there were 21 cases with moderate or severe left atrioventricular valve regurgitation (39.6%). After performing a multivariate analysis, the only significant factor associated with these grades of insufficiency within 30 days of surgical correction of complete atrioventricular septal defect was the absence of Down syndrome (p = 0.03). Group II - At the time of postoperative evaluation, there were 12 cases with moderate or greater LAVVR (23.5%). During univariate analysis, only absence of Down syndrome was statistically significant (p = 0.02). However, after a multivariate analysis, none of the factors reached significance. Conclusion: Absence of Down syndrome proved to be associated with moderate or severe post-operative left atrioventricular valve regurgitation in patients with complete AVSD. However, none of the factors studied was determinant of a moderate or greater LAVVR within the first 30 days of repair of incomplete AVSD at our center. / Introdução: Uma das complicações mais frequentes e importantes do tratamento cirúrgico do defeito de septo atrioventricular (DSAV) é a insuficiência residual da valva atrioventricular esquerda, tanto nas formas totais, como parciais e transicionais. Dessa forma, esse estudo foi conduzido para identificar fatores de risco associados à insuficiência da valva atrioventricular esquerda (IVAVE) de grau moderado ou importante nos primeiros 30 dias após correção de defeito de DSAV. Métodos: Dados de 104 pacientes com DSAV operados entre 2002 e 2010 foram avaliados retrospectivamente, sendo estudados os seguintes fatores de risco: idade e peso no momento da correção, ausência de síndrome de Down, grau de insuficiência da valva atrioventricular (AV) antes da correção, anormalidades na valva AV e uso de anuloplastia. Os pacientes foram separados em dois grupos de acordo com o tipo de DSAV: grupo I (total) e grupo II (parcial e transicional). Características dos 53 pacientes do grupo I: a mediana da idade foi de 6,7 meses e a do peso de 5,3 Kg; 86,8% tinham síndrome de Down; antes da operação, 26 pacientes apresentavam insuficiência pelo menos moderada da valva AV (49.1%); anuloplastia foi realizada em 34% dos pacientes; anormalidades na valva AV foram encontradas em 11.3% dos casos. Características dos 51 pacientes do grupo II: a mediana da idade foi de 4,1 anos e a do peso de 13,4 Kg; 37,2% tinham síndrome de Down; antes da operação, 23 pacientes apresentavam IVAVE pelo menos moderada (45,1%); anormalidades na valva AV foram encontradas em 17,6% dos casos; anuloplastia foi realizada em 21,6% dos pacientes. Resultados: Grupo I – Após a correção cirúrgica, 21 casos apresentaram IVAVE pelo menos moderada (39,6%). Pela análise multivariada, o único fator associado com IVAVE pelo menos moderada no pós-operatório foi ausência de síndrome de Down (p = 0,03). Grupo II - Após a correção cirúrgica, 12 casos apresentaram IVAVE pelo menos moderada (23,5%). Pela análise univariada, apenas a ausência de síndrome de Down teve significância estatística (p = 0.02). Porém, após análise multivariada, nenhum dos fatores teve significância estatística. Conclusão: Ausência de síndrome de Down foi determinante de IVAVE moderada ou importante nos primeiros 30 dias após correção de DSAV total. Todavia, nenhum dos fatores estudados foi determinante para tais graus de IVAVE entre os pacientes com DSAV parcial e transicional.

Submitted by Bruno Cristian Rodrigues (bcr.bruno@hotmail.com) on 2018-05-24T17:50:20Z No. of bitstreams: 1 Dissertação Versão Final.pdf: 1282289 bytes, checksum: 220b5b70a270e2a384dab8b94d207bdc (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-05-28T13:42:27Z (GMT) No. of bitstreams: 1 rodrigues_bc_me_jabo.pdf: 1282289 bytes, checksum: 220b5b70a270e2a384dab8b94d207bdc (MD5) / Made available in DSpace on 2018-05-28T13:42:27Z (GMT). No. of bitstreams: 1 rodrigues_bc_me_jabo.pdf: 1282289 bytes, checksum: 220b5b70a270e2a384dab8b94d207bdc (MD5) Previous issue date: 2018-04-12 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A degeneração mixomatosa da válvula mitral (DMVM) é a enfermidade mais comum na clínica de pequenos animais no âmbito das cardiopatias, cuja evolução pode resultar em alterações hemodinâmicas importantes decorrentes dos mecanismos neuro-hormonais compensatórios. Embora seu diagnóstico seja relativamente simples, as alterações intrínsecas podem ser subestimadas pelos exames convencionais, a exemplo da disfunção sistólica e reserva miocárdica que podem passar despercebidas à ecocardiografia. Desta forma, o objetivo do presente estudo foi avaliar a ocorrência de disfunção sistólica em cães com DMVM por meio do teste de estresse farmacológico com dobutamina. Para tanto, foram utilizados três grupos de cães: G1 (n=8) grupo controle, G2 (n=7) animais com DMVM e diâmetro interno do ventrículo esquerdo em diástole indexado à aorta (DIVEd/Ao) < 2,37 e G3 (n=6) animais com DMVM e DIVEd/Ao ≥ 2,37 em um total de 21 animais. O ecocardiograma foi realizado antes (T0) e após (T1) infusão contínua com dobutamina, que foi realizada da seguinte forma: 5μg/kg/minuto por cinco minutos e 10μg/kg/minuto durante 10 minutos (T1). Os resultados foram avaliados pelo teste de Tukey com nível de significância de 5% quanto às variáveis fração de ejeção (FEJ%) (variação percentual média (VPM) de FEJ% antes e após a infusão de dobutamina), VPM de fração de encurtamento (FEC%) e diâmetros internos do ventrículo esquerdo em sístole e diástole indexados pelo diâmetro da aorta (DIVEs/Ao e DIVEd/Ao). Os resultados acerca da VPM FEC% e VPM FEJ%,demonstraram que houve diferença estatística quanto à primeira variável entre os grupos G1 com G3, bem como entre G2 e G3, enquanto em relação à segunda, apenas o G1 e G3 diferiram estatisticamente. Por outro lado não houve diferença significativa (p>0,05) para as médias obtidas pré e pós dobutamina da FEC% e FEJ% entre todos os grupos, no entanto, houve diferença significativa dentro os grupos G1 e G2 quando analisados os momentos T0 e T1. Outrossim, verificando as médias obtidas do DIVEd/Ao, conclui-se que houve diferença entre os grupos G1 e G3 como também entre G2 e G3 (p<0,05). Por sua vez, as médias obtidas do DIVEs/Ao diferiram significativamente (p<0,05) em todos os grupos pré (T0) e pós dobutamina (T1), exceto no G3. Entre os grupos, as médias no T0, têm diferença estatística significante entre os grupos G1 e G3 (p<0,05). Ademais, Em relação ao VVEs/m², dentro dos grupos houve diferença significativa apenas entre G1 e G3. Já entre os tempos, apenas o G1 houve diferença entre T0 e T1. Por fim, constatou-se significância estatística (p<0,05) quando se correlacionou DIVEd/Ao com a VPM FEC% e VPM FEJ%, demonstrando que quanto maior o DIVEd/Ao menores são estas variáveis. Desta forma, conclui-se que a dobutamina é capaz de evidenciar disfunção sistólica em animais com DMVM, principalmente naqueles que têm um remodelamento maior (G3), sendo capaz de inferir uma forte relação entre o tamanho do DIVEd/Ao e disfunção sistólica. Além disso, notou -se que em animais com menor remodelamento do ventrículo esquerdo (VE), como os do grupo G2, a resposta inotrópica ao desafio farmacológico foi satisfatória, revelando a presença de reserva contrátil nestes pacientes. Por fim, o teste de estresse com dobutamina mostrou-se eficaz, seguro e aplicável na rotina clínica. / Myxomatous mitral valve disease (MMVD) is the most common cardiopathy in small animals, which evolution may result in important hemodynamic changes due to compensatory neurohormonal mechanisms. Although its diagnosis is relatively simple, intrinsic changes may be underestimated by conventional exams, as systolic dysfunction and myocardial reserve that may go unnoticed by echocardiograph. Therefore, the objective of the present study was to evaluate the occurrence of systolic dysfunction in dogs with MMVD through pharmacological stress test with dobutamine. The dogs were distributed in three groups: G1 (n = 8) control group, G2 (n = 7) animals with MMVD and left ventricular diastolic diameter indexed to the aorta (LVIDd:Ao) < 2.37 and G3 (n = 6) animals with MMVD and LVIDd:Ao ≥ 2.37. The echocardiograph was performed before (T0) and after (T1) continuous infusion of dobutamine, as follows: 5μg/kg/minute for five minutes and 10μg/kg/minute for 10 minutes (T1). The results were evaluated by Tukey test with significance level of 5% for the following variables: ejection fraction (EF%) (mean percentage variation (MPV) of EF% before and after dobutamine infusion), MPV of shortening fraction FS% and internal diameters of left ventricle in systole and in diastole indexed by aortic diameter (LVIDs:Ao and LVIDd:Ao). The results about the MPV FS% and the MPV EF% showed that there was statistical difference between the G1 and G3 groups, as well as between G2 and G3, while the G1 and G3 differed statistically from the G1 and G3 groups. On the other hand, there was no significant difference (p> 0.05) for the averages obtained before and after dobutamine of the FS% and EF% among all groups, however, there was a significant difference between groups G1 and G2 when the T0 moments and T1. In addition, it was concluded that there were differences between the G1 and G3 groups as well as between G2 and G3 (p <0.05). Also, by means of the LVIDd:Ao means, it was concluded that there was a difference between the G1 and G3 groups as well as between G2 and G3 (p <0.05). In it’s turn, the means obtained from LVIDs:Ao differed significantly (p <0.05) in all groups before (T0) and post-dobutamine (T1), except in G3. Among the groups, the averages at T0, have significant statistical difference between the G1 and G3 groups (p <0.05). In addition, with respect to ESV/m², within the groups there was a significant difference only between G1 and G3. Among the times, only G1 showed differences between T0 and T1. Finally, statistical significance (p <0.05) was found when DIVEd / Ao correlated with MPV FS% and EF%, demonstrating that the higher the LVIDd:Ao the lower these variables. Therefore, it was determined that dobutamine can point to systolic dysfunction in animals with MMVD, especially those showing greater remodeling (G3), also inferring a strong relationship between LVIDd:Ao size and systolic dysfunction. Furthermore, in animals with less left ventricular (LV) remodeling, such as those in group G2, inotropic response to pharmacological challenge was satisfactory, revealing the presence of contractile reserve in these patients. To conclude, dobutamine stress test showed effective, safe and applicable in clinical routine.