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Biomedical subjects

T Kavanagh

Publications and source records attributed to T Kavanagh.

70 records · Page 4Linked to original sources
PubMed1973

The application of exercise testing to the elderly amputee.

Case histories of 62 elderly amputees with peripheral vascular disease are reviewed. Almost one half had previous infarction, heart failure or digoxin therapy. An arm ergometer test revealed myocardial ischemia in two thirds of the group. The theoretical maximum oxygen intake is low, but many patients were unable to reach the theoretical figure because of myocardial ischemia. Application of these findings to an exercise prescription for amputees is discussed, and it is questioned how many elderly amputees have the potential for useful ambulation.

Adult↗
PubMedDate not supplied

Kinetics of the transplanted heart. Implications for the choice of field-test exercise protocol.

PURPOSE: The transplanted heart shows a slow increase (on transient) of both heart rate (HR) and oxygen consumption (VO2) at the beginning of exercise. The hypothesis used in this study was that this would lead to unacceptably large systematic errors when field predictions of maximal oxygen intake (VO2max) were derived from cycle ergometer tests with a steep ramp function. METHODS: The subjects (27 patients who had received orthotopic heart transplants 6 months previously, and 45 age-matched control subjects) each performed a rapid progressive cycle ergometer test (increments of 16.7 Watts [W] per minute to subjective exhaustion) and a "steady-state" test (two 6-minute stages at one third and two thirds of peak power output). Time constants for HR and VO2 were determined by fitting single exponent equations to the "steady-state" data and noting the time for the difference from the plateau value to reach 36.8% of its initial value. Heart rate and VO2 also were compared between rapid progressive and "steady-state" tests at one third and two thirds of peak power output. RESULTS: At one third of peak power output (46 W in patients, 73 W in control subjects), the respective time constants (mean +/- SE [standard error]) were 60.4 +/- 6.4 and 40.5 +/- 3.0 seconds for VO2 (P < .01), and 130.0 +/- 14.3 and 67.9 +/- 10.0 seconds for HR (P < .001). At two thirds of peak power, the corresponding values were 49.2 +/- 5.5 and 34.7 +/- 2.7 seconds for VO2 (P < .05), and 147.9 +/- 13.0 and 122.2 +/- 4.8 seconds for HR (P < .10). Comparing rapid progressive and "steady-state" readings, the control subjects showed identical values for HR and VO2 at one third of peak power, but at two thirds, the rapid progressive test HR lagged behind the "steady-state" value by 8 +/- 3 beats per minute. The cardiac transplant patients showed a larger HR lag in the rapid progressive tests (109 +/- 12 vs 117 +/- 10 beats per minute, P < .05; 125 +/- 14 vs 141 +/- 14 beats per minute, P < .005). Oxygen consumption also tended to lag slightly at two thirds of peak power (118 +/- 76 mL/min, not significant). CONCLUSIONS: The rapid progressive test protocol yields acceptable field estimates of aerobic power in normal individuals, but the slow acceleration of HR after cardiac transplantation leads to unacceptably large errors if the HR from a rapid progressive test protocol is used to predict maximal oxygen intake (VO2max) in such patients.

Adult↗
PubMedDate not supplied

Exercise training for patients with chronic atrial fibrillation.

BACKGROUND: Patients with atrial fibrillation (AF) referred for exercise rehabilitation exemplify the problem inherent in reliance on pulse rate to prescribe and monitor training intensity. METHODS: Exercise training was accomplished by specifying a training walking pace based on 60% to 80% of the peak oxygen intake (VO2max), as determined by the analysis of expired air (Horizon metabolic cart), and/or the ventilatory threshold (VT), together with a perceived exertion of 12 to 14 on the original Borg scale of perceived exertion. RESULTS: At the end of 1 year, a significant training effect was demonstrated (VO2max average increase 15%, 14.8 +/- 3.6 mL/kg/min to 17.0 +/- 3.6 mL/kg/min, P < .02; VO2 at VT, average increase 14%, 11.2 +/- 2.2 to 12.8 +/- 2.6 mL/kg/min, P < .01; peak power output increase 21%, 92.5 +/- 29.3 Watts to 112 +/- 3.7 Watts, P < .05) in a group of 20 patients (13 men, 7 women) with chronic atrial fibrillation. CONCLUSIONS: Patients with chronic atrial fibrillation can achieve significant functional gains from an exercise rehabilitation program.

Aged↗
PubMedDate not supplied

On the prediction of physiological and psychological responses to aerobic training in patients with stable congestive heart failure.

BACKGROUND: Physiological and psychological markers of patients with congestive heart failure (CHF) who will respond to aerobic training are needed as a guide to appropriate therapy. METHODS: Seventeen of 21 patients with stable CHF completed a 16-week supervised progressive walking program 5 times per week. Cycle ergometer determinations of peak oxygen intake and peak power output at entry and 16 weeks were supplemented by a 6-minute walk, a disease-specific Quality of Life (QOL) questionnaire, and a standard gamble. RESULTS: Peak oxygen intake increased by 2.6 +/- 1.5 mL/(kgmin) over an initial value of 15.6 mL/(kgmin), with parallel gains in peak power and the 6-minute walk. Marked improvements in QOL and standard gamble scores also developed. Initial cardiorespiratory status (heart volume, ejection fraction, oxygen pulse, and peak oxygen intake) was correlated more closely (P = 0.09 to 0.18) with delta peak oxygen intake than with delta peak power or delta walking distance. Physiological gains bore little relationship to initial psychological status. Gains in CHF Questionnaire and Standard Gamble scores were strongly associated with initial scores for these variables (dyspnea, P = .02; mastery, P = .005; standard gamble, P = .001), but could not be predicted from either initial physiological status or gains in physiological condition. CONCLUSIONS: Initial cardiorespiratory status provides little indication of which patients with CHF respond well to training. Gains in QOL score are influenced by initial scores, and seem to show a "ceiling" effect.

Aged↗
PubMedDate not supplied

On-site evaluation of bus drivers with coronary heart disease.

BACKGROUND: Bus drivers with ischemic heart disease have been denied normal employment, although they satisfy Canadian Cardiovascular Society (CCS) Guidelines. To show the safety of their reemployment, we compared their responses when driving buses with those seen during graded exercise testing. METHODS: Twenty-two male city bus drivers, aged 48.1 +/- 5.6 years (19 had a myocardial infarction, 2 had coronary artery bypass graft, 1 had documented ischemic heart disease) were referred for work evaluation. After a CCS cardiopulmonary exercise test, they were accompanied by a physician and a therapist/technician on a normal shift. Note was kept of symptoms, signs, electrocardiogram (telemetry), blood pressure (ambulatory recording unit), and Borg rating of effort throughout. RESULTS: Average values for peak heart rate (101 +/- 12.5 versus 148.2 +/- 17.2 beats/min), peak systolic pressure (150.0 +/- 20.8 versus 198.9 +/- 25.7 mm Hg), peak rate-pressure product (15,259 +/- 3,369 versus 29,500 +/- 5,283 units), peak Borg RPE (9.9 +/- 1.4 versus 17.4 +/- 3.0 units), and peak ST-segmental depression (-0.03 +/- 0.07 versus -0.07 +/- 0.09 mV) during the shift were only about a half of average values reached during the graded stress test. Moreover, peak values were reached at the end of the shift, when carrying the loaded fare box, rather than when driving. CONCLUSIONS: Cardiovascular strain during bus driving is much less than during the CCS stress test for drivers. Using CCS methodology, the risk that a sudden cardiovascular incident will cause injury or death of others in the first year after recovery from myocardial infarction is estimated at 1 in 50,000 driver-years. Thus, those satisfying CCS requirements can return to full driving duties promptly, with minimal risk to themselves, passengers, or other road users.

Adult↗
PubMedDate not supplied

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients.

PURPOSE: Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients. METHODS: Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined. RESULTS: A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training. CONCLUSIONS: These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.

Adaptation, Physiological↗
PubMedDate not supplied

The Toronto Cardiac Rehabilitation and Secondary Prevention Program: 1968 into the new millennium.

Given our approach to the cardiac rehabilitation process, which is reflected in the program structure and services and our high patient volume, this program model is effective for us. The model permits us to treat relatively large number of patients with relatively small numbers of staff. On average, a patient attends 32 supervised exercise sessions at the Centre over the course of 12 months. This is actually fewer supervised sessions than the popular model of 3 times per week for 12 weeks. However, the 12-month program provides an additional 9 months to work with patients on heart-healthy lifestyle modifications. At the same time, we realize our model is not the model of choice for all people in all settings for a variety of reasons. We trust that some elements of our program may be of interest and beneficial to some readers. Undoubtedly, the program will continue to evolve and develop into the future. Currently, we are conducting a cardiac rehabilitation outcomes study in an effort to determine the appropriate duration of cardiac rehabilitation to achieve optimal physiological, psychological, and cost benefits for patients. This study involves more than 700 patients and the results are intended to help us further refine the program structure and selected program elements. As the new millennium approaches, healthcare system reforms and continuing changes in the delivery of medical care to cardiac patients present opportunities, challenges, and some uncertainties for cardiac rehabilitation. To continue our services to patients and the medical community, cardiac rehabilitation programs will need to identify and develop even more innovative and effective concepts in response to ever-changing local, regional, and national issues.

Coronary Disease↗
PubMedDate not supplied

Risk profile and health awareness in male offspring of parents with premature coronary heart disease.

BACKGROUND: The offspring of parents who suffer from premature coronary heart disease have a significantly higher risk of early cardiac death than controls. A genetic predisposition is compounded by a commonality of environmental risk factors within families. Increasing awareness, early detection and modification of risk factors are essential components of an effective public health strategy to protect this highly vulnerable population. METHODS: The sons (n = 571) of parents with premature coronary heart disease attended the Toronto Rehabilitation Centre for a risk factor evaluation that included an interview with questionnaire, measurement of body dimensions and blood lipids, and cardiopulmonary exercise testing. A follow-up questionnaire was sent out 2 years after the evaluation. RESULTS: Despite concern about family history, 23% of subjects were smokers and 75% were inactive. Objective data confirmed a substantial prevalence of cardiac risk factors: less than optimal cardiovascular fitness (48%), overweight (34%), total cholesterol > or = 200 mg/dL (46%), high-density lipoprotein cholesterol < or = 35 mg/dL (26%), low-density lipoprotein cholesterol > or = 160 mg/dL (16%), triglycerides > or = 200 mg/dL (27%), and lipoprotein (a) > 30 mg/dL (24%). Although almost all had a family physician whom they had seen an average of 1.8 times in the past year, and 4.7 times in the previous 3 years, screening and risk factor intervention strategies were disappointing. Two-year follow-up data showed a heightened health awareness, with a greater proportion of subjects exercising and attempting to maintain an appropriate body mass. CONCLUSIONS: The male offspring of parents who have suffered a premature coronary event exhibit a substantial prevalence of modifiable risk factors. The family physician can play an essential role in promoting a healthy lifestyle through risk reduction counselling and screening.

Adult↗
PubMedDate not supplied

Influence of exercise and life-style variables upon high density lipoprotein cholesterol after myocardial infarction.

Two groups of postcoronary patients (n = 35 and n = 27) were followed for 1 year. Group 1, recruited 2 to 3 months after infarction, showed a 9% gain of maximum oxygen intake in response to an average of 878 km of walking at speeds increasing to 6.9 km.hr-1. High density lipoprotein (HDL) cholesterol showed a statistically significant, but small, increase over the period of training. If expressed as a ratio to either low density lipoprotein or total cholesterol, the change was correlated with decreases of cigarette consumption, alcohol intake, and body mass, but was unrelated to speed or training distance. Group 2 patients trained an average of 50 to 80 km a week. In this group, HDL cholesterol correlated well with the weekly running distance, declining in those subjects who detrained, and increasing in those who intensified their training. We conclude that the dose of exercise necessary for inducing any substantial increase of HDL cholesterol is about 20 km.wk-1.

Alcohol Drinking↗