OXYGEN PULSE AS AN INDEPENDENT PREDICTOR OF EXERCISE INTENSITY IN PACED PATIENTS
L. Cook; C. Sharp; E. Busse; R. Haennel; Faculty of Kinesiology & Health Studies, University of Regina and the Regina Health District, Regina, SK
Cardiovascular conditioning results from exercise training performed at intensities above those associated with a maximum stroke volume (SV) (eg, 40%-50% VO2max). If a pacemaker rate response is overly aggressive, the SV contribution to the rise in cardiac output may be compromised, resulting in a disproportionate increase in myocardial oxygen cost for a given power output. An ideal exercise intensity should, therefore, reflect the optimal heart rate (HR) and SV responses.
Purpose:
The purpose of this study was to examine the relationship of heart rate reserve (HRR), metabolic reserve (MR), and oxygen pulse (OP) (VO2/HR) in paced patients to determine if OP could be an independent predictor of exercise intensity. HRR and MR are frequently used to prescribe exercise intensities for pacemaker patients. OP has been proposed as a valid predictor of SV.
Methods:
Nineteen patients (age 72 +/- 3 years; 14 men, 5 women), implanted with a dual QT-AT sensor driven pacemaker (Topaz, Vitatron), performed 3 exercise tests over a 3-week period. The CAEP was performed with sensor modes randomly assigned to activity only (AT), QT only, or dual (AT:QT). For each test, the upper and lower rate limits were set at 140 bpm and 60 bpm, respectively. HR was monitored continuously using a 3-lead ECG (Merlin ER). SV was recorded using Impedance Cardiography (Surcom Inc.). Oxygen uptake (VO2) was measured with the Q-Plex I metabolic cart (Quinton Instrument). For all parameters, data from the last 15 seconds of each stage were analyzed. OP, HRR, and MR were then calculated for each sensor at each stage. Correlation-regression analyses were performed for the relationships in the Table.
Conclusion:
The strong correlation between OP and SV, HRR and MR suggests that OP alone could be used as an independent predictor of the exercise intensity associated with optimal cardiac output response.
EVALUATION OF A STRESS MANAGEMENT PROGRAM FOR CARDIAC REHABILITATION PATIENTS
Rebecca I. Cohen; Laura Cupper; Jean Murray; University of Ottawa Heart Institute, Ottawa, Ontario
Acute and chronic forms of psychosocial stress are thought to contribute to coronary heart disease, and stress management training (SMT) is frequently offered as a component of comprehensive cardiac rehabilitation programs (CR). Limited research has examined the effectiveness of stress management interventions for cardiac patients in clinical settings. The purpose of this study was to evaluate the effectiveness, as measured by changes in perceived stress and body sensations along with patient satisfaction, of a 6-week group-based SMT offered in the context of a comprehensive cardiac rehabilitation program. This psycho-educational program includes relaxation techniques and cognitive restructuring. Forty-eight CR participants (mean age 53.5 years; 7 women, 42 men) completed the Perceived Stress Scale (PSS-10), and the Body Sensations Questionnaire (BSQ) before the group. In addition to a patient satisfaction questionnaire, these measures were repeated after the SMT intervention. Follow-up data were available for 37 out of 48 (77.1%) participants. If data were missing because of loss to follow-up, baseline scores were used in the intent-to-treat analyses. Perceived stress levels were reduced significantly between baseline and follow-up assessment (16.7 vs 14.2, P = < .01). Body sensation levels were unchanged between baseline and follow-up assessment. 95% of participants (35 out of 37) reported that the group was moderately to extremely helpful in assisting to better manage their stress, and that they were using at least one of the SMT techniques more than once a week. These results suggest that the stress management program offered through cardiac rehabilitation may contribute to reductions in patients' levels of perceived stress, and that participants report using the techniques that are taught. Further research is needed to explore long-term outcomes and to conduct randomized controlled trials of the effectiveness of stress management programs with larger samples of cardiac patients.
PREDICTORS OF COMPLIANCE IN A CARDIAC REHAB EXERCISE PROGRAM
Dawn M. Hamilton; Robert G. Haennel; Faculty of Kinesiology and Health Studies, University of Regina, Regina, Saskatchewan
Purpose:
Although it is well known that exercise provides many physical and psychological benefits, only about 50% of those who begin a rehabilitation exercise program are compliant. The purpose of this study was to investigate the dynamics of compliance in a cardiac rehab/risk reduction (CR) population by documenting the extent of noncompliance and dropouts, exploring the reasons for dropping out, and determining the effect of compliance on outcomes.
Methods:
170 new participants (109 men, 61 female; 61 +/- 11 years) in a CR program participated in this study. Tests at baseline, 6, and 12 weeks included the Cardiac Exercise Self-Efficacy Instrument, two measures of functional ability-the 6-minute walk test and the Duke Activity Status Index, and the SF-36 quality of life (QOL) survey. Compliance was defined as reported exercise at least 3 times a week. Both at-home exercise and attendance to the program counted when determining compliance. Participants were deemed dropouts if they failed to attend at least once in a 6-week period.
Results:
50% of participants were compliant in the first 6 weeks, and 57% were compliant in the second 6 weeks. Compliance rate was correlated to a positive change in self-efficacy in the first 6 weeks (P = .02), and a greater increase in QOL in the second 6 weeks (P = .02). Of the 170 new participants, 64 (38%) dropped out of the program before 12 weeks. A larger number of dropouts were attending for the purpose of risk reduction than those who did not drop out (P = .005). Dropouts were younger (57 +/- 12, verses 64 +/- 9 years, P = .001), with the majority quitting within the first 6 weeks (76%). Of the 23 participants who dropped out of the program in the second 6 weeks, only 26% had been compliant (exercised 3 times a week) in the first 6 weeks, verses 55% of those who did not drop out (P = .001). The reasons for dropping out were injury/illness (17), too busy (13), inconvenient place (8) or time (6), moved/vacation (4), further cardiac problems (4), disliked program (3), and death (1). Eight dropouts could not be contacted. No difference was found between dropouts and non-dropouts in diagnosis, gender, or baseline measures of self-efficacy, functional ability, or QOL.
Conclusions:
Only about 50% of participants in CR are compliant, but those who are see larger changes in self-efficacy and QOL. Participants who drop out of CR exercise programs are younger, healthier, and less compliant while attending. Most who drop out will do so in the first 6 weeks, with the most common reasons being injury/illness, too busy, and exercising elsewhere. Participants at risk for dropping out should be identified early so that alternative methods can be explored to help them increase their physical activity in other settings and still reap the health benefits of exercise.
RISK FACTOR AND LIFESTYLE TRENDS FOLLOWING A STANDARD CARDIAC REHABILITATION PROGRAM
Scott A. Lear; Andrew Ignaszewski; Wolfgang Linden; Anka Brozic; Marla Kiess; John J. Spinelli; P. Haydn Pritchard; Jiri J. Frohlich; University of British Columbia, Vancouver, BC, Canada
Cardiac rehabilitation programs (CRP) rely on a relatively short program of risk factor and lifestyle management to achieve lifelong cardiovascular risk reduction. Despite their success, investigations report poor lifestyle adherence and a worsening of risk factors after completion. We report on risk factors and lifestyle behaviors changes 1 year after a standard CRP (as a substudy of a larger randomized trial).
Methods:
Men and women (n = 151) with ischemic heart disease were recruited from two local CRP and returned for outcome assessment 1 year later. Outcomes included fasting serum lipids and glucose, blood pressure (BP), body mass index, waist circumference (WC), smoking status, physical activity, exercise capacity, diet composition, quality of life and angina. Continuous variables were assessed by paired t tests and categorical variables by the McNemar chi square test.
Results:
The initial CRP resulted in significant risk factor reduction. A total of 136 participants returned for the outcome assessment (average 13 months). Those who were lost to follow-up and had a significantly lower exercise capacity at baseline (reasons for loss to follow-up included: did not return contact attempts, moved, or died). The majority of risk factors and lifestyle behaviors after 1 year remained similar to the immediate post-CRP levels. HDL-C, blood glucose, systolic BP, WC, percent dietary fat, and those reporting angina all increased significantly, while TC/HDL-C, physical activity and the illness intrusive rating decreased significantly.
Conclusions:
The observed adverse changes were deemed clinically irrelevant and many of the risk factors remained within a desirable range. These results suggest the that the initial benefits of CRP can be maintained.
WHAT HAPPENS TO THE CARDIOVASCULAR RISK FACTORS OF YMCA HEALTHY HEART MAINTENANCE MEMBERS OVER TIME?
R. Ann Parkinson; Gabriele Scully; Marylce J. Friesen; YMCA Healthy Heart Program, New Westminster, British Columbia
A goal of the YMCA Healthy Heart Program, a community-based outpatient cardiovascular disease prevention, rehabilitation, and maintenance program, is to optimize cardiovascular risk factors of members and to help members maintain these changes over time. Maintenance (mtn) members (attending > 6 months) participate in a program consisting of exercise in supervised classes three times weekly, education, lipid management, ongoing case management and yearly reviews with the medical director. To determine the effectiveness of our maintenance program, functional capacity (FC) in METS, waist circumference (WC) in centimeters (cm), body mass index (BMI in kg/m2), total cholesterol (TC), HDL, LDL, TC/HDL ratio, and triglycerides (TG) were compared on mtn members who had measurements taken in 1999 and again in 2001. The average age of mtn members was 70.5 years in 1999. Mtn members maintained a FC of greater than 8 METS putting them at low risk for future cardiac events (n = 54, average 8.28 METS in 1999 vs 8.27 METS in 2001; NS). The BMI of mtn members remained the same (n = 48, average 26.91 in 1999 vs 26.85 in 2001; NS) and, while not optimal (optimal BMI = 20-25), is not associated with an increased health risk. Waist circumference showed a small decrease (n = 48, average 94.63 cm in 1999 vs 93.93 cm in 2001; NS) and remained slightly above the ideal of 90 cm. Secondary prevention targets used for lipids include a TC < 4.5 mmol/L, HDL > 1.2 mmol/L, LDL < 2.5 mmol/L, TC/HDL ratio < 4.0 mmol/L, and TG < 2.0 mmol/L. Mtn members' lipid profiles showed improvement from 1999 to 2001 with decreases in TC (n = 51, 4.76 vs 4.36 mmol/L, P < .007); TC/HDL ratio (n = 50, 4.24 vs 3.62 mmol/L, P < .01); LDL (n = 46, 2.7 vs 2.35 mmol/L, P < .003); and TG (n = 49, 1.83 vs 1.54 mmol/L, P < .05); and are meeting targets for secondary prevention. HDL levels remained at target (n = 50, 1.27 vs 1.25 mmol/L; NS). Sixty-eight percent of mtn members were on lipid-lowering medications in 1999 compared to 92% in 2001. While BMI and WC are slightly above ideal targets, they are being maintained over time. In conclusion, mtn members are successfully maintaining their FC at levels putting them at low risk of future cardiac events and their lipid profiles showed continued improvement associated with ongoing aggressive pharmacological lipid management.