Typescript (photocopy). / Digitized by Kansas Correctional Industries

The characteristics of the left ventricle of the human heart considered as a pump have been extensively analysed. Using a new approach relying heavily on the Tensor Calculus, a theoretical model describing the mechanical and dynamical operation of the left ventricle has been developed. This has considerably greater versatility than previously proposed models. In particular the physiological shape, both under normal as well as many abnormal situations, is realistically simulated. Further, the mechanical behaviour of the ventricular wall is synthesised from anatomical data concerning the cardiac muscle fibre structure of the wall. Its mechanical and dynamical properties are then, as in the physiological situation, dependent on those of the muscle fibre. These fibre properties have also been fully investigated and a simple new model for cardiac muscle dynamics, incorporating active state, proposed. This description of the ventricular behaviour in terms of muscle properties represents the first logically structured link between cardiac muscle fibre characteristics and ventricular performance.

Thesis (doctoral)--Universitetet i Göteborg.

Thesis (doctoral)--Universitetet i Göteborg.

Clinically, the modified Bruce protocol is widely used to predict functional capacity in cardiac patients. However, it has been suggested that cardiac patients have lower oxygen uptakes for standard workloads. In order to study this, we measured oxygen uptake (V02) and venous bloodV02 derived from lactic acid concentration during a modified Bruce treadmill protocol in 12 pest myocardial infarction (MI) and 12 normal males. During three stages of the protocol mean oxygen uptake was significantly lower (1.42 - 6.2 ml/kg.min; p < .001) for the pest MI than the normal males.However, venous blood lactic acid concentrations were not different at these stages. The MI patients' measured V02 for three stages of the protocol ranged from 1.8 - 7.3 ml/kg.min lower than the Bruce predictions for cardiacs. In addition, measured V02 (max) for cardiac patients were from 3.68 to 11.15 ml/kg.min lower than the predicted the normal subjects. These data suggest myocardial damage may slow oxygen kinetics and results in lower actual V02during treadmill testing. However, blood lactic acid concentrations failed to demonstrate an anaerobic compensation for the lower V02 in pest MI patients.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 12-13).

Typescript (photocopy). / Digitized by Kansas Correctional Industries

An abnormal chronotropic response to exercise is a common finding following surgical repair of tetralogy of Fallot (TOF) which has generally been attributed to a putative sympathetic dysfunction. There exists little information on sympathetic function in patients operated for a congenital heart defect to support such a claim. This study used spectral analysis of heart rate (HRV) and blood pressure (BPV) variability to examine sympathovagal influences on the sinus node in 9 adolescents operated for TOF 13.0 +/- 1.12 years previously and in 8 healthy age and sex-matched control (CTRL) subjects. Continuous ECG and BP recordings were obtained under supine or seated resting positions, with or without controlled respiration at 0.20 Hz (CR); after passive 85° head-up tilt (HUT); during cycling at steady-state heart rates of 100 and 120 bpm (Ex 100, Ex 120), and after 10 and 20 minutes of passive seated recovery. (Abstract shortened by UMI.)

Aim: To determine the prognostic value of cardiopulmonary exercise testing (CPET) for major vascular surgery in South African patients. Methods: CPET has been used in Durban since October 2004 to predict cardiac risk for high-risk patients undergoing major vascular surgery. A submaximal 'anaerobic threshold' (AT) test was conducted on all high-risk patients. Patients were classified into two groups: 'low AT' where the oxygen consumption at the AT was <1 lml.kg^.min"1 for cycling or < 9ml.kg"1.mkf1 for arm cranking and 'high AT' when the patient surpassed these targets. Analysis of all in-hospital deaths following surgery was conducted by two independent assessors blinded to the CPET test result. Deaths classified as primarily 'cardiac in origin' have been used in this retrospective cohort analysis. Results: The AT measured during CPET was not a statistically significant pre-operative prognostic marker of cardiac mortality. However, the survivors of the patients with a 'low AT' may be identified by their response to increasing metabolic demand between 5 and 7 ml.kg^.min"1. Survivors were more dependent on increasing heart rate, while non-survivors were more dependent on oxygen extraction. When this information is added to the AT, CPET was the only test statistically associated with cardiac mortality, in comparison to Lee's Revised Cardiac Risk Index and the resting left ventricular ejection fraction which were not statistically associated with cardiac death. A hundred percent of patients with a positive test died of cardiac causes, while 11% of the patients with a negative test had cardiac deaths. The risk ratio associated with cardiac death following a positive test was 8.00 [95% CI 3.8-16.9]. The sensitivity was 0.25 [95% CI 0.04-0.64], the specificity was 1.00 [95% CI 0.90-1.00], the positive predictive value was 1.00 [95% CI 0.20-0.95] and the negative predictive value was 0.88 [95% CI 0.74-0.95]. Conclusions: CPET provides valuable prognostic information in our surgical population. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2007.

Twelve middle aged men and women (23-59 years) participated in twelve weeks (36 sessions) of endurance swim training at an approximate intensity of 75% maximum heart rate (Karvonen Method) (14). This training resulted in improved cardiorespiratory fitness as evidenced by a significant (9.4%) increase in mean maximal oxygen uptake (liters/ min.) and a significant bradycardial response during submaximal walking. Subjects lost significant amounts of subcutaneous body fat, as measured by skinfold calipers, but experienced very little change in absolute body weight (.1 kg.) suggesting an increase in muscle weight. Data from the submaximal walking test, administered after each 12 session period of training, showed a nonlinear decline in heart rate throughout training. This, possibly, was in response to an accumulating fatigue factor brought on by a rapid increase in the amount of total work that the subjects were doing during the middle stage of training.