Introdução: A hipertrofia ventricular esquerda é importante fator de risco de morbidade e mortalidade cardiovascular. Sua associação com variantes funcionais do sistema renina-angiotensina é controversa. Objetivos: Avaliar a associação entre massa ventricular esquerda e função sistólica e diastólica do ventrículo esquerdo e os polimorfismos inserção/deleção do gene da enzima de conversão da angiotensina e M235T do gene do angiotensinogênio. Métodos: Estudo observacional realizado numa amostra da população da cidade de Vitória (Espírito Santo), utilizando como base a metodologia do projeto Mônica da Organização Mundial da Saúde. Realizamos avaliação clínica, perfil antropométrico, análise laboratorial e ecocardiograma em 652 indivíduos previamente genotipados para polimorfismos da enzima de conversão da angiotensina e do angiotensinogênio. Analisamos massa ventricular esquerda indexada pela área de superfície corpórea e pela altura2,13. Classificamos o ventrículo esquerdo em padrões geométricos: padrão normal, remodelamento concêntrico, hipertrofia concêntrica e hipertrofia excêntrica. A função sistólica ventricular esquerda foi avaliada pela fração de ejeção medida ao modo unidimensional. A função diastólica foi analisada pelo fluxo mitral (onda E, onda A, relação E/A, tempo de desaceleração e tempo de relaxamento isovolumétrico) e pelo Doppler tecidual (velocidade miocárdica em região próxima ao anel mitral septal e lateral: ondas E e A e relação E/E). Resultados: A média de idade da população estudada foi 51 ± 10 anos sendo 59% dos participantes do sexo feminino e 20,8% obesos. Em nossa amostra, 47% dos indivíduos foram classificados como hipertensos. Não houve associação entre hipertensão arterial e os genótipos analisados. Após análise univariada, não encontramos associação entre os polimorfismos inserção/deleção da enzima de conversão da angiotensina e M235T do angiotensinogênio e índice de massa ventricular esquerda, padrões geométricos do ventrículo esquerdo, função sistólica avaliada pela fração de ejeção e os vários parâmetros de função diastólica analisados. / Introduction: Left ventricular hypertrophy is an important risk factor for cardiovascular morbidity and mortality. Its association with the reninangiotensin system genetic variants is controversial. Objectives: To assess the association between left ventricular mass, left ventricle systolic and diastolic functions, and polymorphisms of the insertion/deletion angiotensin converting enzyme and M235T angiotensinogen genes. Methods: Observational study in adults from Vitoria (Brazil) using the methodology of the Monica project of the World Health Organization. We performed clinical examination, anthropometric assessment, laboratory analysis and transthoracic echocargiography studies in 652 adults who were previously genotyped for polymorphisms of the angiotensin-converting enzyme and angiotensinogen. We measured left ventricular mass indexed to body surface area and height 2,13, left ventricular ejection fraction, and diastolic function using mitral flow and tissue Doppler. Left ventricle was classified into following geometric patterns: normal, concentric remodeling, concentric hypertrophy and eccentric hypertrophy. Left ventricular systolic function was assessed by ejection fraction by analysis of the M-mode echocardiogram. Diastolic function was assessed using mitral flow (E wave, A wave, E/A ratio, deceleration time and isovolumic relaxation time), and Doppler tissue imaging (mitral annulus velocity in septal and lateral region: E` and A` waves, and E/E`ratio). Results: Mean age of the studied population was 51±10 years; 59% of the subjects were women and 20,8% were obese. Forty seven percent of the individuals were classified as hypertensive. Hypertension was not associated with any of the studied genotypes. Univarate analysis showed no correlation between polymorphisms of the insertion/deletion angiotensin-converting enzyme and M235T angiotensinogen gene variants, left ventricular mass index, left ventricular geometric patterns, and systolic and diastolic functions. Taking together these data indicated no evidence for the association of ACE and angiotensinogen gene variants with cardiac mass and function assessed by echocardiography.

Submitted in fulfillment of the requirements for the Degree of Masters in Technology: Cardiology, Durban University of Technology, 2012. / Cardiomyopathies and their resultant heart failure (HF) remain a major cause of cardiovascular morbidity and mortality (Wood and Picard, 2004). Idiopathic dilated cardiomyopathy (IDCMO) is a primary myocardial disease of unknown cause, characterized by left ventricular (LV) or biventricular dilatation and impaired myocardial contractility. Dilated cardiomyopathy (DCMO), along with rheumatic heart disease and hypertension (HPT), is one of the leading causes of HF in Africa. In fact, in an epidemiology study of 884 patients in Soweto, IDCMO was the second major cause of HF. Thirty five percent of patients in the study, with HF, had IDCMO (Sliwa, Damasceno, Mayosi, 2005). Methodology: Patients referred to the cardiomyopathy (CMO) clinic at Chris Hani Baragwanath hospital, situated in the echocardiographic lab, were recruited, provided they satisfied the exclusion and inclusion criteria and were enrolled after obtaining voluntary informed consent. From May 2009 to September 2010, 70 patients with IDCMO were recruited for this trial. Patients with DCMO were identified by means of echocardiographic criteria which included a left ventricular ejection fraction (LVEF) of less than 45% and an end diastolic dimension (EDD) of greater than of 52 mm (2D in long parasternal axis). Results: In the present study the prevalence of left ventricular (LV) thrombus in patients with IDCMO was 18.6%. When using Univariate logistic regression, the only independent predictors of LV thrombus formation was LVEF and age. However, when multivariate logistic regression analysis was applied to the data, the only predictor with a significant association was age. The reason for this is not clear. It is postulated that perhaps younger patients have differences in the pathophysiology of their disease such as a greater smoldering inflammatory component which may therefore predispose them to thrombus formation. For example the presence of IL-6 may be important in the formation of LV clot in cases of LV dysfunction (Sosin, Bhatia, Davis, Lip, 2003). The association between LVEF and LV thrombus was borderline significant. Conclusion: The prevalence of LV thrombus formation in this cohort of patients with IDCMO was 18.6%. Echocardiographic parameters alone cannot predict which patients are more likely to develop thrombus formation. / National Research Foundation / M

Abstract Collagen XIII is a type II transmembrane protein, which has a short intracellular domain and a large, mainly collagenous ectodomain. It is located at many cell-matrix junctions and in focal adhesions in cultured cells and it has a function in cell adhesive processes. Overexpression of collagen XIII molecules with an 83 amino acid deletion in part of the ectodomain leads to fetal lethality in Col13a1del transgenic mice. Doppler ultrasonography was performed at 12.5 days of gestation on fetuses resulting from heterozygous matings and matings between heterozygous and wild-type mice. Some fetuses had atrioventricular valve regurgitation (AVVR) and all of them were transgene positive. In addition, fetuses had pathological changes in functional parameters. Histological analysis showed the trabeculation of the ventricles to be reduced and the myocardium to be thinner in the fetuses with AVVR. Based on in situ hybridization (ISH), collagen XIII mRNA are normal constituents of these structures. Overexpression of mutant collagen XIII results in mid-gestation cardiac dysfunction in fetuses, and these disturbances in cardiac function may lead to death in utero. The heterozygous mice that were initially of normal appearance had an increased susceptibility to develop B cell lymphomas, which originated in the mesenteric lymph node. Collagen XIII protein was not detected in normal lymph nodes or in the lymphomas. The incidence of lymphomas was higher in conventional conditions than in a specific pathogen-free facility. In addition, the expression of collagen XIII was localized in the intestine and the basement membrane was highly abnormal. These findings suggest that collagen XIII is a critical determinant of lymphanogenesis. Using ISH, antibody staining and RT-PCR techniques collagen XIII expression was analyzed during carcinogenesis in mice and in man. Collagen XIII expression increased during carcinogenesis in mice and in man. In the malignant process collagen XIII mRNA localized in the basal epithelium and in the invasive cells. According to antibody staining malignant invasive cells were positive. Results may reflect the disturbed adhesion of epithelial cells and ECM and that may affect the behaviour of the malignant cells, suggesting that collagen XIII has a significant role in the initiation of the invasion.

This study used an in situ heart preparation to analyze the power and work of spontaneously beating hearts of four anurans (R. marina, L. catesbeianus, X. laevis, P. edulis) and three urodeles (N. maculosus, A. tigrinum, A. tridactylum) in order to elucidate the meaning of relative ventricle mass (RVM) in terms of specific cardiac performance variables. This study also tests two hypotheses: 1) the ventricles of terrestrial species (R. marina, P. edulis, A. tigrinum) of amphibians are capable of greater maximum power outputs (Pmax) compared to aquatic species (X. laevis, A. tridactylum, N. maculosus, L. catesbeianus) and, 2) the ventricles of Anuran species (R. marina, P. edulis, L. catesbeianus, X. laevis) are capable of greater maximum power output compared to aquatic species (A. tigrinum, A. tridactylum, N. maculosus). The data supported both hypotheses. RVM was significantly correlated with Pmax, stroke volume, cardiac output, afterload at Pmax, and preload at Pmax. Preload at Pmax and afterload at Pmax also correlated very closely with each other, suggesting that an increase blood volume and/or increased modulation of sympathetic tone may influence interspecific variation RVM and may have played a role in supporting higher rates of metabolism, as well as dealing with hypovolemic stresses of life on land.

Orientadores: Carlos Kenichi Suzuki, Aron José Pazin de Andrade / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-21T07:29:25Z (GMT). No. of bitstreams: 1 Silva_BrunoUtiyamada_M.pdf: 3089036 bytes, checksum: 01d1bb268591e2388a9bb34046fbd188 (MD5) Previous issue date: 2012 / Resumo: Neste trabalho, foi realizado um estudo experimental de uma Bomba de Sangue Ápice Ventricular (BSAV) para sua análise como um dispositivo de assistência ventricular. Este estudo faz parte do desenvolvimento desta bomba e serviu como fundamentação na evolução do projeto. A BSAV é uma bomba de sangue centrífuga de fluxo contínuo, para ser utilizada como dispositivo de assistência ventricular em pacientes com doenças cardíacas crônicas. Foi realizado um estudo de posicionamento anatômico, onde a bomba foi implantada em um coração de um porco e não foram encontrados indícios de possíveis danos aos tecidos e órgãos circunvizinhos. Em seguida, foi feito um ensaio experimental, onde foi comparado o desempenho de protótipos com características distintas, visando sua otimização em relação ao desempenho hidrodinâmico. Também foi realizado um estudo para avaliação do trauma as células do sangue causado pela ação da bomba, no qual os resultados mostraram um baixo dano as células. A seguir, foi feito estudo com um protótipo conectado em um simulador cardiovascular híbrido (matemático e físico), onde este protótipo às condições simuladas de um sistema cardiovascular com insuficiência cardíaca. Com a BSAV conectada ao sistema obteve-se, uma melhora no fluxo de sangue, frequência cardíaca e pressão aórtica. Os resultados indicam que a BSAV é adequada para aplicação como dispositivo de assistência ventricular esquerda e é uma alternativa promissora no tratamento de pacientes com doenças cardíacas crônicas / Abstract: In this work an experimental study was realized with the Apico-Ventricular Blood Pump (AVBP) used as a ventricular assist device. This study is part of the device's development and the results were used for project evaluation and improvement. AVBP is a continuous flow centrifugal blood pump for ventricular assistance in chronic cardiac patients. Initially, an anatomic study was performed, in this study an AVBP prototype was implanted in a corpse of a pig, the clinical staff appointed, none damage to the nearby tissues and organs due to the contact with the device. Following step consists in an experimental hydrodynamic performance test. For this test the prototypes used had distinct specific construction characteristics variations among themselves, for device optimization, the performance of these different prototypes were compared, and the prototypes which presented a better performance had their characteristic adopted in the project. A study to determine the traumatic effect of the pump on blood cells was conducted, the results showed low damage to the blood cells. A hybrid mock loop circulation system (mathematical and physic) where the pump, was connected to a system with heart disease, was used. When the AVBP was inserted in the system, cardiac output, heart rate and aortic pressure went to normal values. All results indicated the performance of the AVBP as ventricular assist device, an alternative for treatment of patients with cardiac chronic diseases / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Introduction: Venoarterial extracorporeal membrane oxygenation (VA ECMO) is widely used in the treatment of circulatory failure, but repeatedly, its negative effects on the left ventricle (LV) have been observed. The purpose of this study is to assess the influence of ex- tracorporeal blood flow (EBF) on systemic hemodynamic changes and LV performance parameters during VA ECMO therapy of decompensated heart failure. Methods: Porcine models of low-output chronic and acute heart failure were developed by long-term fast cardiac pacing and coronary hypoxemia, respectively. Profound signs of circulatory decompensation were defined by reduced cardiac output and tissue hypoperfusion. Sub- sequently, under total anesthesia and artificial ventilation, VA ECMO was introduced. LV performance and organ specific parameters were recorded at different levels of EBF using an LV pressure-volume loop analysis, arterial flow probes on carotid and subclavian arteries, and transcutaneous probes positioned to measure cerebral and forelimb regional tissue oxygen saturations. Results: Conditions of severely decompensated heart failure led to systemic hypotension, low tissue and mixed venous oxygen saturations, and increase in LV end-diastolic pressure. By increasing the EBF from minimal flow to 5 L/min, we observed a...

Objetivo: O principal propósito do estudo foi pesquisar a disfunção ventricular esquerda subclínica em pacientes com lúpus eritematoso sistêmico juvenil (LESJ) através da técnica de speckle-tracking bidimensional. Foi investigada ainda uma possível correlação entre o comprometimento da deformação miocárdica e o SLEDAI-2K (Systemic Lupus Erithematosus Disease Activity Index 2000), bem como a presença de fatores de risco cardiovascular, tanto tradicionais como ligados à doença. Métodos: 50 pacientes assintomáticos do ponto de vista cardiovascular e 50 controles saudáveis (14,74 vs. 14,82 anos, p=0.83) foram avaliados pelo ecocardiograma convencional e pelo speckle-tracking bidimensional. Resultados: Apesar da fração de ejeção normal, os pacientes apresentaram redução de todos os parâmetros de deformação miocárdica longitudinal e radial, quando comparados aos controles: strain de pico sistólico longitudinal [-20,3 (-11 a -26) vs. -22 (-17,8 a -30.4) %, p < 0,0001], strain rate de pico sistólico longitudinal [-1,19 ± 0,21 vs. -1,3 ± 0,25 s-1, p=0,0005], strain rate longitudinal na diástole precoce [1,7 (0,99 a 2,95) vs. 2 (1,08 a 3,00) s-1 , p=0,0034], strain de pico sistólico radial [33,09 ± 8,6 vs. 44,36 ± 8,72%, p < 0,0001], strain rate de pico sistólico radial [1,98 ± 0,53 vs. 2,49 ± 0,68 s-1, p < 0,0001] e strain rate radial na diástole precoce [-2,31 ± 0,88 vs. -2,75 ± 0,97 s-1, p=0,02]. O strain de pico sistólico circunferencial [-23,67 ± 3,46 vs. - 24,6 ± 2,86%, p=0,43] e o strain rate circunferencial na diástole precoce [2 (0,88 a 3,4) vs. 1,99 (1,19 a 3,7) s-1, p=0,88] foram semelhantes em pacientes e controles. Apenas o strain rate de pico sistólico circunferencial [-1,5 ± 0,3 vs. -1,6 ± 0,3 s-1, p=0,036] mostrou-se reduzido no LESJ. Uma correlação negativa foi identificada entre o strain de pico sistólico longitudinal e o SLEDAI-2K (r = - 0,52; p < 0,0001) e também o número de fatores de risco cardiovascular por paciente (r = -0,32, p=0,024). Conclusões: Foi evidenciada disfunção sistólica e diastólica subclínica de ventrículo esquerdo no LESJ através da técnica de speckle-tracking bidimensional. A atividade da doença e a exposição aos fatores de risco cardiovascular provavelmente contribuíram para o comprometimento da deformação miocárdica nesses pacientes / Objectives: The main purpose of the study was to investigate left ventricular (LV) subclinical systolic and diastolic dysfunction in childhood-onset systemic lupus erythematosus (c-SLE) patients using two-dimensional speckletracking (2DST) echocardiography. We also interrogated possible correlations between impairment of myocardial deformation and the SLE Disease Activity Index 2000 (SLEDAI-2K), as well as the presence of traditional and disease-related cardiovascular risk factors (CRFs). Method: A total of 50 asymptomatic patients and 50 controls (age 14.74 vs. 14.82 years, p = 0.83) were evaluated by standard and 2DST echocardiography. Results: Despite a normal ejection fraction (EF), there was reduction in all parameters of LV longitudinal and radial deformation in patients compared to controls: peak longitudinal systolic strain [-20.3 (-11 to -26) vs. -22 (-17.8 to -30.4)%, p < 0.0001], peak longitudinal systolic strain rate [-1.19 ± 0.21 vs. -1.3 ± 0.25 s-1, p = 0.0005], longitudinal strain rate in early diastole [1.7 (0.99-2.95) vs. 2 (1.08-3.00) s-1, p = 0.0034], peak radial systolic strain [33.09 ± 8.6 vs. 44.36 ± 8.72%, p < 0.0001], peak radial systolic strain rate [1.98 ± 0.53 vs. 2.49 ± 0.68 s-1, p < 0.0001], and radial strain rate in early diastole [-2.31 ± 0.88 vs. -2.75 ± 0.97 s-1, p = 0.02]. Peak circumferential systolic strain [- 23.67 ± 3.46 vs. -24.6 ± 2.86%, p=0.43] and circumferential strain in early diastole [2 (0,88 a 3,4) vs. 1,99 (1,19 a 3,7) s-1, p=0.88 ] were similar between patients and controls, although peak circumferential systolic strain rate [-1.5 ± 0.3 vs. -1.6 ± 0.3 s-1, p = 0.036] was reduced in c-SLE. Further analysis of patients revealed a negative correlation between LV peak longitudinal systolic strain and SLEDAI-2K(r= -0.52, p < 0.0001) and also between LV PLSS and the number of CRFs per patient (r = -0.32, p = 0.024). Conclusions: 2DST echocardiography has identified subclinical LV deformation impairment in c-SLE patients. Disease activity and cumulative exposure to CRFs contribute to myocardial compromise

Objetivo: O principal propósito do estudo foi pesquisar a disfunção ventricular esquerda subclínica em pacientes com lúpus eritematoso sistêmico juvenil (LESJ) através da técnica de speckle-tracking bidimensional. Foi investigada ainda uma possível correlação entre o comprometimento da deformação miocárdica e o SLEDAI-2K (Systemic Lupus Erithematosus Disease Activity Index 2000), bem como a presença de fatores de risco cardiovascular, tanto tradicionais como ligados à doença. Métodos: 50 pacientes assintomáticos do ponto de vista cardiovascular e 50 controles saudáveis (14,74 vs. 14,82 anos, p=0.83) foram avaliados pelo ecocardiograma convencional e pelo speckle-tracking bidimensional. Resultados: Apesar da fração de ejeção normal, os pacientes apresentaram redução de todos os parâmetros de deformação miocárdica longitudinal e radial, quando comparados aos controles: strain de pico sistólico longitudinal [-20,3 (-11 a -26) vs. -22 (-17,8 a -30.4) %, p < 0,0001], strain rate de pico sistólico longitudinal [-1,19 ± 0,21 vs. -1,3 ± 0,25 s-1, p=0,0005], strain rate longitudinal na diástole precoce [1,7 (0,99 a 2,95) vs. 2 (1,08 a 3,00) s-1 , p=0,0034], strain de pico sistólico radial [33,09 ± 8,6 vs. 44,36 ± 8,72%, p < 0,0001], strain rate de pico sistólico radial [1,98 ± 0,53 vs. 2,49 ± 0,68 s-1, p < 0,0001] e strain rate radial na diástole precoce [-2,31 ± 0,88 vs. -2,75 ± 0,97 s-1, p=0,02]. O strain de pico sistólico circunferencial [-23,67 ± 3,46 vs. - 24,6 ± 2,86%, p=0,43] e o strain rate circunferencial na diástole precoce [2 (0,88 a 3,4) vs. 1,99 (1,19 a 3,7) s-1, p=0,88] foram semelhantes em pacientes e controles. Apenas o strain rate de pico sistólico circunferencial [-1,5 ± 0,3 vs. -1,6 ± 0,3 s-1, p=0,036] mostrou-se reduzido no LESJ. Uma correlação negativa foi identificada entre o strain de pico sistólico longitudinal e o SLEDAI-2K (r = - 0,52; p < 0,0001) e também o número de fatores de risco cardiovascular por paciente (r = -0,32, p=0,024). Conclusões: Foi evidenciada disfunção sistólica e diastólica subclínica de ventrículo esquerdo no LESJ através da técnica de speckle-tracking bidimensional. A atividade da doença e a exposição aos fatores de risco cardiovascular provavelmente contribuíram para o comprometimento da deformação miocárdica nesses pacientes / Objectives: The main purpose of the study was to investigate left ventricular (LV) subclinical systolic and diastolic dysfunction in childhood-onset systemic lupus erythematosus (c-SLE) patients using two-dimensional speckletracking (2DST) echocardiography. We also interrogated possible correlations between impairment of myocardial deformation and the SLE Disease Activity Index 2000 (SLEDAI-2K), as well as the presence of traditional and disease-related cardiovascular risk factors (CRFs). Method: A total of 50 asymptomatic patients and 50 controls (age 14.74 vs. 14.82 years, p = 0.83) were evaluated by standard and 2DST echocardiography. Results: Despite a normal ejection fraction (EF), there was reduction in all parameters of LV longitudinal and radial deformation in patients compared to controls: peak longitudinal systolic strain [-20.3 (-11 to -26) vs. -22 (-17.8 to -30.4)%, p < 0.0001], peak longitudinal systolic strain rate [-1.19 ± 0.21 vs. -1.3 ± 0.25 s-1, p = 0.0005], longitudinal strain rate in early diastole [1.7 (0.99-2.95) vs. 2 (1.08-3.00) s-1, p = 0.0034], peak radial systolic strain [33.09 ± 8.6 vs. 44.36 ± 8.72%, p < 0.0001], peak radial systolic strain rate [1.98 ± 0.53 vs. 2.49 ± 0.68 s-1, p < 0.0001], and radial strain rate in early diastole [-2.31 ± 0.88 vs. -2.75 ± 0.97 s-1, p = 0.02]. Peak circumferential systolic strain [- 23.67 ± 3.46 vs. -24.6 ± 2.86%, p=0.43] and circumferential strain in early diastole [2 (0,88 a 3,4) vs. 1,99 (1,19 a 3,7) s-1, p=0.88 ] were similar between patients and controls, although peak circumferential systolic strain rate [-1.5 ± 0.3 vs. -1.6 ± 0.3 s-1, p = 0.036] was reduced in c-SLE. Further analysis of patients revealed a negative correlation between LV peak longitudinal systolic strain and SLEDAI-2K(r= -0.52, p < 0.0001) and also between LV PLSS and the number of CRFs per patient (r = -0.32, p = 0.024). Conclusions: 2DST echocardiography has identified subclinical LV deformation impairment in c-SLE patients. Disease activity and cumulative exposure to CRFs contribute to myocardial compromise

University of Macau / Faculty of Science and Technology / Department of Electrical and Electronics Engineering

Global and regional mechanics of the cardiac ventricles were investigated using an anatomicallyaccurate computational model formulated from concise mathematical descriptions ofthe left and right ventricular wall geometries and the non-homogeneous laminar microstructureof cardiac muscle. The finite element method for finite deformation elasticity was developedfor the analysis and included specialised coordinate systems, interpolation schemesand parallel processing techniques for greater computational efficiency.The ventricular mechanics model incorporated the fully orthotropic pole-zero constitutivelaw, based on the three-dimensional architecture of myocardium, to account for the nonlinearmaterial response of resting cardiac muscle, relative to the three anatomically relevant axes.A fibre distribution model was introduced to reconcile some of the pole-zero constitutiveparameters with direct mechanical properties of the tissue (such as the limiting strainsestimated from detailed physiological observations of the collagen helices that surroundmyofibres), whilst other parameters were estimated from in-vitro biaxial tension tests onthin sections of myocardium. A non-invasive approach to in-vivo myocardial materialparameter estimation was also developed, based on a magnetic resonance imaging techniqueto effectively tag ventricular wall tissue.The spatially non-homogeneous distribution of myocardial residual strain was accounted forin the ventricular mechanics model using a specialised growth tensor. A simple model of fluidshift was formulated to account for the changes in local tissue volume due to movement ofintramyocardial blood. Contractile properties of ventricular myofibres were approximatedusing a quasi-static relationship between the fibre extension ratio, intracellular calciumconcentration and active fibre stress, and the framework has been developed to include amore realistic model of active myocardial mechanics, which could be coupled to a realisticdescription of the time-varying spread of electrical excitation throughout the ventricularwalls. Simple volumetric cavity models were incorporated to investigate the effects of arterialimpedance on systolic wall mechanics.Ventricular mechanics model predictions of the cavity pressure versus volume relationships,longitudinal dimension changes, torsional wall deformations and regional distributions ofmyocardial strain during the diastolic filling, isovolumic contraction and ejection phasesof the cardiac cycle showed good overall agreement with reported observations derivedfrom experimental studies of isolated and in-vivo canine hearts. Predictions of the spatialdistributions of mechanical stress at end-diastole and end-systole are illustrated.