No description available.

No description available.

No description available.

Conventional echocardiographic parameters are currently used in determining the timing for surgery in patients with mitral regurgitation. Since brain natriuretic peptide (BNP) rises in response to ventricular muscle stretch, and is to detect early heart failure, we hypothesized that BNP would be activated in patients with regurgitant valvular heart disease and concomitant left ventricular dilatation. Aim/Objectives: We therefore studied the pattern of changes in NT-pro BNP in patients with chronic severe rheumatic mitral regurgitation who were undergoing mitral valve replacement and compared this with the newer modality of tissue Doppler imaging (TDI). Setting: Patients submitted to surgery were prospectively evaluated over 8 months at Inkosi Albert Luthuli Central Hospital, Department of Cardiology. Controls were obtained from the outpatients' follow-up clinic. Methods: Simultaneous quantification of the severity of mitral regurgitation (MR), left ventricular (LV) end systolic volume (ESV), left atrial (LA) volume and Doppler filling ratios (mitral (E)/annulus (Ea)) were performed at baseline in all patients and was repeated at 1-week and at the six-week follow-up visit in surgical patients. Results: Both groups were similar for age and gender and echo-Doppler parameters in all patients preoperatively except LA size (p< 0.01) and volume (p<0.004) which were more elevated in the surgical group. Mean NT-pro BNP levels were markedly elevated preoperatively (262 pmolll) in all surgical cases compared to controls (57 pmol/l; p=0.0001). NT-pro BNP levels increased further at one week post surgery (395 pmol/l) and subsided at the six week follow-up visit (94 pmol/I). These changes were accompanied by significant reduction in LA (p= 0.003) and LV chamber dimensions (EDD = 0.004) with an increase in the ejection fraction from 42% at one week to 52 % at six weeks. Four patients had abnormally elevated NT-pro BNP levels (>53pmol/l) at the 6-week follow-up visit. A ROC curve was constructed for all variables to separate surgical cases from controls. The area under the curve was highest for NT-pro BNP (sensitivity= 96%, specificity 45 %). Conclusion: 1. There was a significant difference in the left atrial chamber size and volume, as well as Em/Ea (TDI) and NT-proBNP levels preoperatively between the two groups. The lack of a significant difference in the LV parameters between surgical and control groups suggest an almost total reliance on symptoms in deciding the timing of surgery which was reflected by markedly elevated NT-pro BNP in all surgical patients. 2. Postoperatively, there was a significant reduction in LA and LV dimensions. 3. The high false positivity rate for NT-pro BNP suggests that the test is most likely reflecting early LV decompensation in the less symptomatic control patients who rightly need surgery. 4. Tissue Doppler indices had similar sensitivity but low specificity compared to NT-proBNP. 5. Serial estimations of NT-pro BNP may prove useful in selecting patients for surgery. / Thesis (M.Med.Sc.)-University of KwaZulu-Natal, 2007.

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No description available.

Currently, mitral valve repair techniques have shown substandard mid-term and long term results. In order to improve the efficacy of these repair techniques, detailed knowledge of normal mitral valve function and the alterations to the valvular and subvalvular apparatus which occur under pathological conditions is required. Furthermore, current techniques may be optimized through a better understanding of the function and mechanics of the mitral valve after a particular repair. The experiments which comprise this study were designed using an in vitro approach since this technique has the clear advantage of isolating and independently controlling specific parameters that are of importance to valvular mechanics and function. The experiments were conducted in the Georgia Tech Left Heart Simulator using native porcine and human mitral valves. The first set of experiments measured the chordal force distribution and anterior leaflet strain of the mitral valve in its normal geometrical configuration. Subsequent experiments measure mitral regurgitation volume and chordal force distribution in conditions associated with ventricular dilation. The last set of experiments simulated two commonly used mitral repair techniques. For the Alfieri stitch experiments, the effects of mitral flow rate, transmitral pressure, and mitral annular area on valve stenosis, mitral regurgitation and Alfieri stitch force were evaluated. For annuloplasty, the effect of annular saddle curvature on anterior leaflet strain was quantified. In Conclusion, the normal geometry of the native mitral valve optimized its function and mechanics. Under pathological conditions associated with ventricular dilation, significant alterations to mitral valve function and mechanics were present. Although the studied repair techniques may have significantly restored valve function, severe alterations to the mechanics of the valve still persisted.

Orientador: Maria Jaqueline Mamprim / Banca: Maria Lucia Gomes Lourenço / Banca: Noeme Sousa Rocha / Banca: Raquel Sartor Marcelino / Banca: Maria Cristina Ferrarini Nunes Soares Hage / Resumo: A doença degenerativa crônica da válvula mitral é a doença cardíaca com maior frequência e uma das causas da insuficiência cardíaca em cães. O objetivo do estudo foi descrever e comparar nos rins, velocidade de pico sistólico, velocidade diastólica final, índice de resistividade e índice de pulsatilidade das artérias renais e interlobares; e no fígado as dimensões, áreas e relações da artéria aorta, veia cava caudal e veia porta; volume de fluxo da veia porta e índice de congestão portal; e índice de resistividade da artéria hepática em 19 cães com doença degenerativa crônica da válvula mitral classificados em três grupos (B2, C e D) de acordo com American College of Veterinary Internal Medicine (ACVIM). Os resultados mostraram que o índice de resistividade e o índice de pulsatilidade renais aumentaram com a progressão da doença. Com relação aos dados do fígado, o índice de congestão portal aumentou com a evolução da doença e o volume de fluxo portal apresentou o mesmo perfil observado em outras hepatopatias, como cirrose. Os resultados do presente trabalho são complementares na avaliação de cães com doença degenerativa crônica da válvula mitral, auxiliando no diagnóstico e no tratamento desses animais / Abstract: Chronic degenerative mitral valve disease is heart disease more often and one of the causes of heart failure in dogs. The aim of the study was to describe and compare the kidneys, peak systolic velocity, end diastolic velocity, resistive index and pulsatility index of renal and interlobar arteries; and liver dimensions, areas and relationships of the aorta, caudal vena cava and portal vein; volume flow of the portal vein and portal vein congestion index; and resistivity index of the hepatic artery in 19 dogs with chronic degenerative mitral valve disease classified into three groups (B2, C, D) according to the American College of Veterinary Internal Medicine (ACVIM). The results showed that the resistivity index and renal pulsatility index increased with disease progression. With regard to liver data, the congestion index increased with the progression of the disease and the volume of portal blood flow showed the same profile observed in other liver diseases such as cirrhosis. The results of this work are complementary in the evaluation of dogs with chronic mitral valve degenerative disease, aiding in the diagnosis and treatment of these animals / Doutor

Made available in DSpace on 2016-07-01T13:10:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-12-04. Added 1 bitstream(s) on 2016-07-01T13:14:16Z : No. of bitstreams: 1 000866930_20171204.pdf: 151813 bytes, checksum: 5891c0f5459b827277f3fbcf1b192a23 (MD5) Bitstreams deleted on 2017-12-08T12:00:19Z: 000866930_20171204.pdf,. Added 1 bitstream(s) on 2017-12-08T12:01:09Z : No. of bitstreams: 1 000866930.pdf: 1291614 bytes, checksum: d2bf753766399d454c170a4db80890aa (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A doença degenerativa crônica da válvula mitral é a doença cardíaca com maior frequência e uma das causas da insuficiência cardíaca em cães. O objetivo do estudo foi descrever e comparar nos rins, velocidade de pico sistólico, velocidade diastólica final, índice de resistividade e índice de pulsatilidade das artérias renais e interlobares; e no fígado as dimensões, áreas e relações da artéria aorta, veia cava caudal e veia porta; volume de fluxo da veia porta e índice de congestão portal; e índice de resistividade da artéria hepática em 19 cães com doença degenerativa crônica da válvula mitral classificados em três grupos (B2, C e D) de acordo com American College of Veterinary Internal Medicine (ACVIM). Os resultados mostraram que o índice de resistividade e o índice de pulsatilidade renais aumentaram com a progressão da doença. Com relação aos dados do fígado, o índice de congestão portal aumentou com a evolução da doença e o volume de fluxo portal apresentou o mesmo perfil observado em outras hepatopatias, como cirrose. Os resultados do presente trabalho são complementares na avaliação de cães com doença degenerativa crônica da válvula mitral, auxiliando no diagnóstico e no tratamento desses animais / Chronic degenerative mitral valve disease is heart disease more often and one of the causes of heart failure in dogs. The aim of the study was to describe and compare the kidneys, peak systolic velocity, end diastolic velocity, resistive index and pulsatility index of renal and interlobar arteries; and liver dimensions, areas and relationships of the aorta, caudal vena cava and portal vein; volume flow of the portal vein and portal vein congestion index; and resistivity index of the hepatic artery in 19 dogs with chronic degenerative mitral valve disease classified into three groups (B2, C, D) according to the American College of Veterinary Internal Medicine (ACVIM). The results showed that the resistivity index and renal pulsatility index increased with disease progression. With regard to liver data, the congestion index increased with the progression of the disease and the volume of portal blood flow showed the same profile observed in other liver diseases such as cirrhosis. The results of this work are complementary in the evaluation of dogs with chronic mitral valve degenerative disease, aiding in the diagnosis and treatment of these animals