Background: Stroke volume (SV) and aortic valve area calculations require the left ventricular (LV) outflow tract (LVOT) or aortic annular area calculations that involve squaring the respective diameters. Area calculation errors became evident with transcatheter aortic valve replacement where areas were underestimated due to an elliptical annulus. We hypothesized that LVOT and annular shape are more elliptical in patients with greater relative LV wall thickness (RWT) leading to underestimation of SV index using 2D Doppler echocardiography. Methods: We studied 203 consecutive patients referred to an outpatient noninvasive laboratory for Doppler echocardiograms which included acceptable 3-dimensional images. 3-dimensional assessment of the LVOT at 3–5 mm from the valve insertion, at the site of valve insertion, and at the sinus of Valsalva (SOV) was performed with assessment of the minor axis (MN), major axis (MJ), and areas at mid-systole. SV index was calculated from LVOT and annular diameters obtained from 2-dimensional echo and from 3-dimensional LVOT areas. Results: An inverse relation of RWT with MN/MJ at mid-systole for the LVOT (r = 0.5812, P < 0.0001) and annulus (r = 0.6865, P < 0.0001) was noted. LVOT and annulus areas were similar among groups at mid-systole. SV index calculated from 2D LVOT dimensions was significantly smaller than using 3D LVOT areas (35.6 ± 8.9 vs 53.6 ± 16.1 mL, P < 0.0001). Conclusion: There is an inverse relation between MN/MJ and RWT at the LVOT and aortic annulus despite the LVOT and annular areas being similar across most geometries resulting in SV index underestimation calculated using LVOT diameters vs 3D LVOT areas.

This thesis consists of a preface and twenty-one original short stories. The preface examines the differences between creative nonfiction, autobiography, and memoir. The twenty-one interrelated stories included are autobiographical in nature, in some ways memoirs and in some ways creative nonfiction. The over-all theme of the collection explores one character's journey of self-discovery and transformation.

Left ventricular hypertrophy (LVH), the detection of which is recommended for routine risk prediction by all guidelines, is more prevalent in groups of African ancestry. This is in-part attributed to higher prevalence rates of obesity. The ability to detect LVH using electrocardiographic (ECG) criteria may be modified in groups of African ancestry. The impact of co-existent obesity on the ability to detect ECG-LVH in this ethnic group has not been determined. Moreover, whether estimated glomerular filtration rate (eGFR) or serum C-reactive protein (CRP concentrations are independently associated with LV mass index (LVMI) and can therefore be used to complement ECG criteria for LVH detection is uncertain. ECG voltage criteria for the detection of echocardiographic LVH were evaluated in 661 participants from a community sample of African ancestry (43% obese). Body mass index (BMI) was inversely associated with Sokolow-Lyon (SL) voltages (partial r=-0.27, p<0.0001) and no BMI-Cornell voltage relations were noted (p=0.21). BMI was associated with voltage criteria that incorporate only limb lead recordings (r=0.17-0.23), but these relationships were weaker than BMI-LVMI relations (r=0.36, p<0.01-p<0.0001 for comparisons of r values). All ECG criteria were as strongly related to blood pressure (BP) as LVMI. Sokolow-Lyon voltage-LVMI relations were noted only after adjustments for BMI (p<0.02) and SL voltages showed no performance for LVH detection. Cornell voltages showed significant performance in the non-obese (area under the receiver operating curve [AUC]=0.67±0.04, p<0.0005), but not the obese (AUC=0.56±0.04, p=0.08). ECG criteria which employ limb-lead recordings only (e.g. RaVL) showed better performance in non-obese than obese (AUC=0.75±0.04 and 0.59±0.04 respectively, p<0.005 for comparison) and markedly reduced specificity for LVH detection in obese (76%) than non-obese (92%, p<0.0001) despite similar sensitivities (32 vs 29%). Thus, in groups of African ancestry, obesity contributes toward a poor validity and performance of all voltage criteria for the detection of LVH. None of the current criteria are recommended for use in obesity in groups of African descent. Alternative approaches are required for LVH detection in these groups.In 621 randomly selected participants from the community sample [332 were normotensive (NT)], eGFR was associated with LVMI and LVM in excess of that predicted from stroke work (inappropriate LVM, LVMinappr) in all participants (LVMI: partial r=-0.18, p<0.0001; LVMinappr: partial r=-0.17, p<0.0001) and NT (LVMI: partial r=-0.23,p<0.0001; LVMinappr: partial r=-0.22, p<0.0001) separate from hypertensives. When replacing clinic BP with either aortic systolic BP (applanation tonometry and SphygmoCor software), 24-hour BP, aortic pulse wave velocity (PWV) (applanation tonometry and SphygmoCor software), stroke work (for LVMI), LV end diastolic diameter (LVEDD), or circumferential wall stress in the regression models, eGFR retained strong associations with LVMI (p=0.01 to <0.0001) and LVMinappr (p<0.005 to <0.0001). Thus, strong relationships between eGFR and LVM occur at a community level irrespective of the presence of hypertension and independent of 24-hour and aortic BP, PWV, LVEDD,stroke work and wall stress. The independent relationships between eGFR and LVMI, support the notion that eGFR may be evaluated for LVH detection. In 361 randomly selected participants from a community with a high prevalence of CRP concentrations considered to be high-risk (54.0%), but without cardiovascular or renal disease, serum CRP concentrations were correlated with both LVMI and LVMinappr (p<0.0001). With adjustments for a number of potential confounders including age, systolic BP, waist circumference (or BMI), and glucose control (glycated haemoglobin), the relationships between serum CRP concentrations and both LVMI and LVMinappr (partial r=0.11, p<0.05 for both) persisted. The independent relationship between CRP and LVMI or LVMinappr translated into a higher multivariate-adjusted LVMI and LVMinappr values in the highest as compared to the lowest quartile of CRP (LVMI; highest quartile CRP=48.8±10.7, lowest quartile CRP=45.0±11, p<0.05; LVMinappr; highest quartile CRP=137±24, lowest quartile CRP=127±24, p<0.05). The independent relationships between CRP and LVMI, support the notion that CRP may also be evaluated for LVH detection. In 358 participants from a randomly selected community sample with a high prevalence of obesity (41%), a combination of CRP concentrations and eGFR above or below the median for the sample respectively showed significant performance (AUC=0.61±0.03, p<0.0005), but a low specificity for LVH detection (77%). When eGFR and CRP concentrations were employed to complement RaVL, although the overall performance did not improve (AUC=0.71±0.03, p<0.0005, RaVL alone: AUC=0.70±0.03), the specificity increased (93%) whilst sensitivity (25%) was in-line with previously reported sensitivities for LVH detection using ECG criteria in alternative population samples. Without changing overall performance, eGFR together with RaVL increased the specificity to 88% and CRP concentrations when considered together with RaVL increased the specificity to 87%. Thus, in a community sample where the specificity and performance of ECG criteria for LVH detection are poor, the use of eGFR and/or CRP concentrations to complement ECG criteria increase the specificity without altering the overall performance. In conclusion, the present thesis provides evidence to indicate that current ECG criteria for the detection of LVH are invalid in obese individuals of African ancestry, but that clinical markers of renal dysfunction and systemic inflammation, which are associated with LVMI independent of haemodynamic factors and co-morbidities may be employed to complement ECG criteria to improve the specificity for LVH detection.

Left ventricular hypertrophy (LVH) and increases in large artery stiffness predict cardiovascular outcomes in patients with renal failure. What determines left ventricular mass index (LVMI) and large artery stiffness and the contribution toward LVH and large artery dysfunction is not entirely clear. Consequently, this cross sectional study was aimed at assessing the various factors impacting on LVH in haemodialysis (HD), to contribute toward our understanding of the pathophysiology of LVH and large artery dysfunction in 94 adult HD patients. Pre- and post-dialysis blood pressures (BPs) were determined over 12 sessions of dialysis and averaged. Pulse wave analysis performed at the carotid, femoral and radial arteries was employed to determine pulse wave velocity (PWV) and central augmentation index (AIc). Echocardiography was performed to determine left ventricular mass (LVM) indexed to body surface area (LVMI). Natriuretic peptides, procollagen type I c-peptide (PIP), c-terminal telopeptide of type I collagen (ICTP), matrix metalloproteinases and their inhibitors were studied. The prevalence of LVH was 72.8 % (67/92) .On multivariate analysis pre- (p≤ 0.005), post- (p<0.05) and averaged dialysis (p < 0.015) systolic BP were associated with LVMI and PWV. 24 hour (r = 0.260, p = 0.026), day (r = 0.247, p = 0.036), and night (r= 0.241, p = 0.042) systolic BP were not more closely associated with LVMI than the averaged dialysis systolic BP (r = 0.272, p = 0.010). Similarly 24 hour (r = 0.41, p = 0.0003), day (r=0.400, p = 0.0005), and night (r =0.416, p = 0.0003) systolic BP were not more closely associated with PWV than the post-dialysis systolic BP (r=0.39, p=0.0001) indicating that these BP measurements are as effective as 24-hour ambulatory BP in predicting cardiovascular target organ changes. No relationship between either PWV (r=-0.08), or AIc (r=-0.10) and LVMI, between PWV (r=-0.11), or AIc (r=0.03) and LV MWT was noted. IVCD was independently associated with LVMI (partial r adjusted for average dialysis SBP=0.27, p=0.014; partial r adjusted for 24-hour SBP=0.29, p=0.013), and LV mean wall thickness (p<0.01), but not with LV relative wall thickness (p=0.18), or LV end diastolic diameter (p=0.88). An association between IVCD and AIc (partial r adjusted for average dialysis SBP=0.21, p<0.05), but not PWV was noted. NT-proANP and NT-proBNP were independently associated with LVMI (p<0.0001) but neither were associated with IVCD independent of LVMI suggesting a close association with LVMI in HD. Serum concentrations of matrix metalloproteinases 1, 2 and 9, and their tissue inhibitors (1 and 2) were not associated with LVMI, remodelling or PWV and neither procollagen I nor the C-terminal telopeptide of type I collagen (ICTP) were associated with LVMI. Thus, factors impacting on LVH in this study were systolic BP, NT-proANP, NT-proBNP and IVCD.

In this thesis, we described our efforts to achieve antenna radomes that enhance antenna gain by using the artificial synthesis structure of the left-handed material. The characteristics of the metamaterial are introduced. Also, we will analyze the phenomena of the left-handed material which distinguish them from the right-handed material. Moreover, we analyze and derive the theory to obtain the effect of the meta-materials with the metal line artificial synthesis array structure. Then, we will focus on the method of lowering the frequency of the left-handed material structure and discuss the frequency influence of the permeability, permittivity, and refractive index as the modulus of the refractive index is smaller than one or negative. We will adjust the structure to allow a wider useful frequency bandwidth. In order to prevent from the reflection of the metal lines to cause too much loss, we will simplify the structure of the single unit. Making use of the above-mentioned methods, we use the material to achieve an antenna radome. The meta-material radome can reduce the 3 dB beam-width by about 30 percent compared with the conformal patch at 5.25 GHz. Finally, we design a novel structure of unit cell based on the CSRR which is provided with a broadband negative index of refraction. The relative bandwidth of the LHM proposed in this thesis is 36.5%. In order to reduce loss tangent we remove the dielectric substrate, which further reduce the 3 dB beam-width.

Left ventricular (LV) volume analysis in small animals has proven difficult because of the small size of the hearts and the rapid heart rate. Furthermore, there is a substantial contribution to the signal from both the blood as well as the muscle. Admittance - based measurement techniques has been proven effective in eliminating the muscular component and estimating the blood component accurately. The key factor that makes this measurement effective is the fact that the measurement is made in the complex plane, which measures both the magnitude as well as the phase of the complex phasor. This dissertation presents the design of a wireless telemetric device that measures impedance magnitude and phase measurements along with pressure from conscious, ambulatory rats. Using this impedance data along with other calibration data such as blood resistivity, stroke volume etc., volume is determined. / text

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