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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Biomechanical and Hemodynamic Measures of Right Ventricular Diastolic Function: Translating Tissue Biomechanics to Clinical Relevance

Jang, Sae, Vanderpool, Rebecca R., Avazmohammadi, Reza, Lapshin, Eugene, Bachman, Timothy N., Sacks, Michael, Simon, Marc A. 12 September 2017 (has links)
Background Right ventricular (RV) diastolic function has been associated with outcomes for patients with pulmonary hypertension; however, the relationship between biomechanics and hemodynamics in the right ventricle has not been studied. Methods and Results Rat models of RV pressure overload were obtained via pulmonary artery banding (PAB; control, n=7; PAB, n=5). At 3 weeks after banding, RV hemodynamics were measured using a conductance catheter. Biaxial mechanical properties of the RV free wall myocardium were obtained to extrapolate longitudinal and circumferential elastic modulus in low and high strain regions (E-1 and E-2, respectively). Hemodynamic analysis revealed significantly increased end-diastolic elastance (E-ed) in PAB (control: 55.1 mm Hg/mL [interquartile range: 44.785.4 mm Hg/mL]; PAB: 146.6 mm Hg/mL [interquartile range: 105.8155.0 mm Hg/mL]; P=0.010). Longitudinal E1 was increased in PAB (control: 7.2 kPa [interquartile range: 6.718.1 kPa]; PAB: 34.2 kPa [interquartile range: 18.144.6 kPa]; P=0.018), whereas there were no significant changes in longitudinal E-2 or circumferential E-1 and E-2. Last, wall stress was calculated from hemodynamic data by modeling the right ventricle as a sphere: (stress = Pressure x radius/2 x thickness Conclusions RV pressure overload in PAB rats resulted in an increase in diastolic myocardial stiffness reflected both hemodynamically, by an increase in E-ed, and biomechanically, by an increase in longitudinal E-1. Modest increases in tissue biomechanical stiffness are associated with large increases in E-ed. Hemodynamic measurements of RV diastolic function can be used to predict biomechanical changes in the myocardium.
12

Myocardial Fibrosis in Patients With Symptomatic Obstructive Hypertrophic Cardiomyopathy: Correlation With Echocardiographic Measurements, Sarcomeric Genotypes, and Pro-Left Ventricular Hypertrophy Polymorphisms Involving the Renin-Angiotensin-Aldosterone System

Blauwet, Lori A., Ackerman, Michael J., Edwards, William D., Riehle, Darren L., Ommen, Steve R. 01 September 2009 (has links)
Introduction: Hypertrophic cardiomyopathy (HCM) is a heterogeneous disorder of the cardiac sarcomere, resulting in myocyte hypertrophy and disarray, interstitial fibrosis, and cardiac dysfunction. Our aim was to determine whether the amount of fibrosis in HCM correlates with echocardiographic measures of diastolic dysfunction, presence of HCM-susceptibility mutations, or polymorphisms in the renin-angiotensin-aldosterone system (RAAS). Methods: Surgical specimens from patients with obstructive HCM undergoing septal myectomy at the Mayo Clinic (2001-2004) were examined and compared with autopsy-derived tissues from age- and sex-matched normal controls. Digital image analysis was used to quantitate the fibrosis in representative microscopic sections. Genotyping was performed for myofilament-HCM using polymerase chain reaction, high-performance liquid chromatography, and direct DNA sequencing. RAAS polymorphism status was similarly established. Results: The study included 59 HCM cases and 44 controls. Patients with HCM exhibited more fibrosis (mean 17%, range 3-45%) than controls (mean 8%, range 3-17%) (P<.0001). A significant relationship existed between amount of fibrosis and maximum wall thickness (P=.02), left ventricular ejection fraction (P=.02), and peak early/late diastolic mitral annulus velocity (E/A ratio) (P=.002). Although there was no association between amount of fibrosis and myofilament-HCM genotype status or polymorphisms in the RAAS cascade, there was a trend toward more fibrosis in patients with ≥1 C-encoding allele in CYP11B2-encoded aldosterone synthase. Conclusions: Patients with HCM undergoing septal myectomy had significantly more myocardial interstitial fibrosis than controls. The amount of fibrosis in HCM patients correlated with degree of septal hypertrophy and left ventricular systolic and diastolic function. Notably, neither mutations in cardiac myofilament proteins or polymorphisms in RAAS exhibited strong associations with severity of myocardial fibrosis.
13

TGF-β<sub>1</sub> Overexpression: A Mechanism of Diastolic Filling Dysfunction in the Aged Population

Larson, Douglas F., Ingham, Rene, Alwardt, Cory M., Yang, Bo 01 March 2004 (has links)
The prevalence of cardiovascular disease in the United States dramatically increases with age. A hallmark feature of the aged myocardium is increased fibrosis resulting in diastolic dysfunction. Moreover, the survival of patients subsequent to a myocardial infarction is inversely related to age because of a certain extent to maladaptive remodeling mediated by cardiac fibroblasts. Our hypothesis is that cardiac fibroblast (CF) dysfunction results in overexpressed TGF-β1 leading to increased cardiac collagen content in the aged population. TGF-β1 stimulates the synthesis of the extracellular matrix proteins, including collagen in the cardiac tissues. The RT-PCR analysis of mRNA expression of TGF-β1 of the CF was increased by 43% in the aged mice as compared to the younger. The stiffness of the left ventricle is expressed with the slope of the end-diastolic pressure-volume relationship parameter, β (mmHg/μL). In a mouse model, we demonstrated that β was 0.30 ± 0.05 in the young as compared to 0.52 ± 0.10 in the aged (p < .05). The ventricular stiffness was associated with the myocardial collagen content; namely, young versus the aged was 9.5 ± 4.0 as compared to 16.4 ± 2.3% of total protein, respectively (p < .05). In conclusion, the gene structure-function relationships support our hypothesis that cardiac fibroblast disregulation contributes to diastolic filling dysfunction in elderly persons. These data provide a potential contributory mechanism for diastolic dysfunction that may be vital in caring for the aged open-heart surgical patient.
14

Diastolic Function Grading by American Society of Echocardiography Guidelines and Prediction of Heart Failure Readmission and All-Cause Mortality in a Community-Based Cohort

Lavine, Steven J., Murtaza, Ghulam, Rahman, Zia U., Kelvas, Danielle, Paul, Timir K. 01 January 2021 (has links)
Background: Diastolic function (DF) guidelines have been simplified but lack extensive outcome data. Using a rural university heart failure (HF) database, we assessed whether DF grading could predict HF, HF readmission, and all-cause mortality (ACM). Methods: In this single-center retrospective study that included 613 patients in sinus rhythm hospitalized for HF (HF with preserved—254 patients, with mid-range—216 patients, and reduced ejection fraction—143 patients), we recorded demographics, Doppler-echo, Framingham HF score, laboratories, HF readmission, and ACM with follow-up to 2167 days. Results: Diastolic dysfunction (Ddys) parameters (left atrial volume index [LAVI] > 34 ml/m2, tricuspid regurgitation [TR] velocity > 2.8 m/sec, and E/e’ > 14) had moderate sensitivity (46.2%–65.0%) for predicting HF among all phenotypes combined with DF grading having moderate predictability and additive to a clinical composite for HF prediction (AUC =.677, P < 0.0001; difference =.043, P < 0.001) for combined phenotypes. Ddys parameters and Ddys severity (2016 ASE criteria: grade II and III) were significantly associated with HF readmission for decompensated HF within 60–2167 days of follow-up (LAVI > 34 ml/m2: HR 1.56 [1.26–2.19]; E/e’ > 14: HR 1.44 [1.21–1.99]; TR > 2.8 m/sec: H1.43 [1.19–1.88]; LV Dys grade II: HR 2.12 [1.42–2.96]; LV Ddys grade III: HR 2.39 [1.57–4.82]). Conclusion: The findings of this study highlight the clinical and prognostic relevance of determining the severity of LV Ddys in patients with HF with regard to HF verification and HF readmission.
15

Constrictive Pericarditis: A Commonly Missed Cause of Treatable Diastolic Heart Failure

Bhattad, Pradnya B., Jain, Vinay 08 May 2020 (has links)
Constrictive pericarditis arises as a result of the fibrous thickening of the pericardium due to chronic inflammatory changes from various injuries. Increased pulmonary and systemic venous pressures manifest clinical features of left and right heart failure. Idiopathic or post-viral pericarditis is the most common cause followed by postpericardiotomy, radiation-induced causes. Right-sided heart failure symptoms predominate over left-sided heart failure symptoms due to the equalization of pressures. No single diagnostic test can provide a definitive diagnosis or evidence of constrictive pericarditis. Medical management is difficult for constrictive pericarditis. The treatment of choice for constrictive pericarditis is pericardiectomy.
16

Relationship between Diabetic Control and Presence of Diastolic Dysfunction on Echocardiogram in Elderly Patients with Type 2 Diabetes

Bocirnea, Cristina 24 August 2012 (has links)
No description available.
17

Plasma N-terminal Proatrial Natriuretic Peptide Concentration in Cats with Hypertrophic Cardiomyopathy

MacLean, Heidi Norma 26 March 2004 (has links)
Objective: We sought to determine N-terminal proatrial natriuretic peptide concentrations [Nt-proANP] in plasma from cats with hypertrophic cardiomyopathy (HCM). Secondarily, we wished to evaluate the relationship between [Nt-proANP] and echocardiographic variables. Methods: Venous blood samples were obtained from seventeen cats with HCM and from nineteen healthy cats. Plasma [Nt-proANP] was determined using an ELISA assay. The relationship between plasma [Nt-proANP] and M-mode, 2-dimensional and Doppler echocardiographic variables was evaluated. Cats that were hyperthyroid or had evidence of renal disease were excluded from the study. Results: The mean plasma [Nt-proANP] was higher in cats with HCM (3.81 +/- 1.23 pmol/l) than in control cats (3.08 +/- 1.41 pmol/l); however, this difference was not statistically significant (p=0.17). There was a significant correlation between plasma [Nt-proANP] and left ventricular posterior wall thickness (r = 0.42; p=0.01). Additionally, plasma [Nt-proANP] was correlated with left atrial size (r = 0.35; p=0.03). A linear regression model was developed to further explore these relationships. LAs2D and LVPWd had an interactive effect on plasma [Nt-proANP] (R2 = 0.2737; p= 0.02). There was no correlation between any other echocardiographic variable and plasma [Nt-proANP]. There was no correlation between plasma [Nt-proANP] and heart rate (HR), body-weight, or age. Conclusions: Cats with HCM do not have significantly higher plasma [Nt-proANP] than normal cats. There was a significant linear relationship between [Nt-proANP] and LAs2D, LVPWd and the model that described their interaction. / Master of Science
18

Diastolic echocardiographic parameters in patients with atrial fibrillation

Iqbal, Hena January 2017 (has links)
Vid flertalet hjärtsjukdomar kan det förekomma störningar i den diastoliska funktionen, detta tillstånd benämns diastolisk dysfunktion. Detta innebär att fyllnadstrycken i vänsterkammare ökar på grund av nedsatt eftergivlighet i kammaren. Bedömning av diastolisk funktion, hos patienter som utvecklat förmaksflimmer, är en utmaning inom ekokardiografi. Detta beror på att förmaksflimmer innebär utebliven förmakskontraktion, oregelbunden längd av hjärtcykeln och förmaksdilatation, vilket försvårar bedömningen. Syftet med studien var att med ekokardiografi studera diastoliska parametrar hos patienter med förmaksflimmer för att studera om dessa kan användas vid bedömning av den diastoliska vänsterkammarfunktionen hos denna patientgrupp. I studien inkluderades 37 deltagare med förmaksflimmer som var remitterade för en ekokardiografisk undersökning med olika frågeställningar. Pulsad doppler teknik och vävnads doppler teknik användes för att registrera följande diastoliska parametrar: förmaksvolym, mitralisinflöde (E-vågshastigheten) och myokardiets diastoliska hastigheter (e´). Utöver dessa uppskattades även ejektionsfraktion, hjärtfrekvens, hypertrofi och trycket i lilla kretsloppet, som togs med vid bedömningen. Mann-Whitneys test visade att det förelåg ett starkt statistiskt samband mellan fyllnadstrycket (E/e´) och E-vågen, e ´samt förmaksvolym (p = <0,05). Signifikant resultat erhölls även för sambandet mellan PA-tryck och fyllnadstryck (p = 0,014) genom ett chitvå-test. Vidare gav multipel linjär regression utslag på E-vågen och e´. Analysen visade att det förelåg en hög förklaringsgrad för E-vågen (p = <0,001) och e´ (p = 0,008). Sammanfattningsvis visade resultaten att ekokardiografi kan användas för diagnostik av förmaksflimmerpatienter avseende fyllnadstryck där förmaksvolym, E-vågshastigheten och e´ anses vara bästa parametrarna. / In the majority of heart diseases disturbances in the diastolic function may occur, this condition is called diastolic dysfunction. This means that the left ventricular filling pressure increases due to reduced compliance in the chamber. The assessment of diastolic function in patients who have developed atrial fibrillation (AF), is a challenge in echocardiography. This is a result of AF which involves absence of atrial contraction, irregular length of the cardiac cycle and left atrium dilatation that complicates the assessment. The aim of this study was to observe the diastolic echocardiographic parameters in patients with AF to examine if these can be used in the assessment of diastolic left ventricular function in this population. The study included 37 participants with AF who were remitted for an echocardiographic examination due to various concerns. Pulsed Doppler technique and tissue Doppler technique was used to record the following diastolic parameters: atrial volume, mitral inflow velocity (E) and the myocardial diastolic velocity (e'). Ejection fraction, heart-rate, hypertrophy and pulmonary artery pressure were also estimated and included in the assessment. Mann-Whitneys test showed that there was a strong statistical correlation between the filling pressure (E/e') and E, e' and atrial volume (p = <0.05). Significant results were also obtained for the relation between pulmonary artery pressure and the filling pressure (p = 0.014) by a chi-square test. A multiple linear regression showed association between E and e'. The analysis showed that there was a significant value of coefficient of determination for E (p = <0.001) and e' (p = 0.008). In conclusion, the results showed that echocardiography can be used for diagnosis of AF patients regarding filling pressures, where atrial volume, E velocity and e' are considered to be the best parameters.
19

Einfluss von körperlichem Training auf natriuretische Peptide, Adrenomedullin und Endothelin sowie auf Parameter der Belastbarkeit und der kardialen Funktion bei Patienten mit diastolischer Herzinsuffizienz / Effects of exercise training on natriuretic peptides, Adrenomedullin and Endothelin, exercise capacity and cardiac function in patients with diastolic heart failure

Rutscher, Tinka 03 June 2015 (has links)
No description available.
20

Einfluss einer diabetischen Stoffwechsellage auf die diastolische Funktion des linken Ventrikels / Influence of diabetes mellitus on left ventricular diastolic function

Schönbrunn, Lisa Christiane 10 August 2011 (has links)
No description available.

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