Vita. / Digitized by Kansas State University Libraries

Call number: LD2668 .T4 1966 N761 / Master of Science

The aim of the research was to investigate the effects of three parameters of the artificial heart on the (+) dP/dt max. The study was conducted using a mock circulation which was connected to an artificial heart. The data were collected using the COMDU software developed for the computer which monitors the artificial heart. Stepwise regression analysis was utilized to test the three hypotheses. Two of the null hypotheses for the study could not be rejected, as the independent variable did not significantly affect (+) dP/dt max. Although the third hypothesis was accepted, the results were not clinically significant. Limitations in the study were multicollinearity among the independent variables, small sample size, and the inability of the mock circulation to represent human responses.

There is increasing interest in right ventricular function as an important determinant of cardiac output. However, the chamber is difficult to study, because of its shape and relationship to the left ventricle. Invasive studies, radionuclide studies and two-dimensional echocardiography are all useful approaches, but all have serious limitations. Systolic time intervals, best measured by pulsed Doppler ultrasound in the proximal pulmonary artery, offer one method of assessing right ventricular systolic function. Previous "normal" ranges, however, could be criticised on many counts. I present data from carefully checked normal controls and compare to previous publications, and explore variability and relationships between the various systolic time intervals. Most variables have skewed frequency distributions; the ranges are somewhat wider than previously described; most heart rate corrections are found to have serious limitations; and the effect of age is explored. Complete heart block offers a model to study the the effects of varying atrioventricular intervals whilst the ventricular rate is held unphysiologically steady by an artificial pacemaker. Given the current controversy about the merits of single- versus dual-chamber pacing, the issue is of topical interest also. The effect of varying the "P-R" interval within the physiological range is explored, and "optimal" ranges identified. A curious "nadir" effect, previously unknown, was discovered. When P waves followed paced QRS complexes at about 50-100ms, forward flow into the pulmonary artery (as judged from systolic time intervals) fell in most patients, and in some subjects virtually ceased. As a small included invasive part of the study showed, this was accompanied by falls in RV systolic pressure and rises in right atrial pressure. This study demonstrates that right ventricular systolic time intervals can be used to study right ventricular function in pacing situations, and is further evidence of the unsatisfactory nature of single-chamber ventricular pacing.

published_or_final_version / Nursing Studies / Master / Master of Nursing

The statistical correlations between habitual diet and plasma risk factors for coronary heart disease CHD were analyzed using multiple regression. Thirty-one male subjects between 30-56 years kept complete dietary records for 7 days. Daily means of nutrient consumption were calculated using a computerized data base. Fourteen independent variables (total kilocalories, protein %, carbohydrate %, fat %, ethanol %, caffeine, P/S ratio, cholesterol, age, weight, height , weight**.75, Body Mass Index, kilocalories/weight**.75) were created. Plasma samples were analyzed and the following simple (total plasma cholesterol (TC), VLDL-C, LDL-C, HDL2-C, HDL3-C, apo A-I, apo A-II, apo B) and derived (VLDL-C+LDL-C, LDL-C/TC, LDL-C/HDL-C, HDL-C, HDL2-C/HDL3-C, HDL-C/TC, apo B/apo A-I, apo B/apo A-II, apo A-Il/apo A-I) dependent variables were created. Dependent variables were individually regressed against the entire set of independent variables. An F-value of 4.00 to enter an independent variable in the model and of 3.99 to remove one were used to achieve significance of p<05. Age appeared in 5 regression models (TC, apo B, apo B/apo A-I, apo B/apo A-II, apo A-Il/apo A-I) and was positively correlated with increased risk for CHD. Total kilocalories appeared in 4 models (LDL-C, apo B, VLDL-C+LDL-C, LDL/TC) and was negatively correlated with risk. Fat % appeared in 4 models (VLDL-C+LDL-C, LDL/TC, LDL-C/HDL-C, HDL-C/TC) and was associated with increased risk. Body Mass Index was entered in 2 models (HDL2-C, HDL-C) and was positively correlated with risk. P/S ratio was negatively correlated with risk in the three models (HDL2, apo A-I, HDL-C) in which it appeared. The independent variable carbohydrate % was negatively associated with risk in 2 models, LDL-C and apo B. Kcal/wt**.75 was also negatively correlated with risk in the VLDL-C, LDL-C/TC and HDL-C/TC models. One independent variable, EtOH %, was positively associated with risk in the apo A-II and apo A-II/apo A-I models. Two dependent variables did not have any independent predictors (HDL3-C, HDL2-C/HDL3-C) entered in their regression models. Six independent variables did not appear in any regression model (protein %, caffeine, cholesterol, weight, height, weight**.75). Independent variables positively correlated with increased risk for CHD were therefore fat %, ethanol %, age, and Body Mass Index. Independent variables correlated with decreased risk for CHD were total kilocalories, carbohydrate %, P/S ratio, and kilocalories/weight**.75. / Graduation date: 1985

No description available.

No description available.

No description available.

No description available.