Cardiac rehabilitation for women: a systematic review.

PURPOSE: Current cardiac rehabilitation (CR) evidence was systematically evaluated to identify program components that may yield improvements in physiological and psychosocial outcomes in women. METHODS: A search was conducted in the electronic databases: MEDLINE, Embase, CINAHL, Scopus, Sport Discus and Cochrane Library. Search terms included women, heart disease, exercise therapy, and cardiac rehabilitation. A systematic elimination process was used with specific inclusion/exclusion criteria. Included articles were independently evaluated by four reviewers for level of evidence and internal validity. Specific recommendations were made based on trends in the literature and strength of supporting evidence. RESULTS: Thirty-seven articles were included with a combined sample of 3,807 subjects. Ten studies included an analysis of physiological effects of exercise. Aerobic, resistance, and combined exercise interventions all yield physiological benefits. CR yielded favourable health-related quality of life outcomes and women benefited from psychosocial support in both formal and informal environments. CONCLUSIONS: The following recommendations are based on the review: 1) For patients with good cardiac function, community/home-based programs are as effective as supervised programs (Level II, B); 2) resistance training should be included as an adjunct to aerobic training (Level I, A); 3) programs need to address the specific educational needs of women (Level I, A) and a stronger emphasis needs to be placed on social support (Level II, B).

A prediction model for estimating pulmonary oxygen uptake during the 6-minute walk test in organ transplant recipients.

We developed a multivariate prediction equation for estimating the highest obtainable pulmonary oxygen uptake (VO2p) during the 6-minute walk test (6-MWT) in 54 organ transplant recipients: heart/heart-double-lung (n=14), kidney/kidney-pancreas (n=16), liver (n=14), double lung (n=8), bone marrow (n=2). They were of age, 48+/-12 years. Participants performed a 6-MWT during which expired gases were collected and analyzed with a portable metabolic system interfaced with a wireless heart rate monitor. The following variables significantly contributed to the model for predicting the highest obtainable 6-MWT VO2p: 6-MWT distance (m), age (years), gender (male=0, female=1), resting heart rate, peak heart rate, weight (kg), and transplant type (kidney/kidney-pancreas=1, other=0), where: VO2p=1.253+0.022 (6-MWT distance)+0.112 (age) -3.192 (gender) -0.104 (resting heart rate)+0.127 (peak 6-MWT heart rate)-0.084 (weight)+2.116 (transplant type). The explanatory variables in our final model accounted for 78% of the variance in 6-MWT VO2p. In conclusion, the addition of an easily estimated 6-MWT VO2p will provide added clinical information of functional capacity following an exercise rehabilitation intervention or during routine follow-up for organ transplant recipients.

Validity and reliability of a medicine ball explosive power test.

The purpose of this study was to evaluate the validity and reliability of a medicine ball throw test to assess explosive power. Twenty competitive sand volleyball players (10 male players, 10 female players) performed a medicine ball throw and a standard countermovement vertical jump. The subjects attended 2 sessions; at each session, 3 attempts of each test were completed. The movement pattern for the medicine ball throw was a backward overhead toss. To standardize for body weight, a power index was calculated for the countermovement vertical jump using the Lewis formula. Validity was assessed using the best score for both the throw and the jump, and reliability was assessed using the best score from each session. There was a strong correlation between the distance of the medicine ball throw and the power index for the countermovement vertical jump (r = 0.906, p < 0.01). For the countermovement vertical jump, the test-retest reliability was 0.993 (p < 0.01), and for the medicine ball throw, the test-retest reliability was 0.996 (p < 0.01). These findings suggest that the medicine ball throw test is a valid and reliable test for assessing explosive power for an analogous total-body movement pattern and general athletic ability.

Validity and reliability of the 6-minute walk test in a cardiac rehabilitation population.

PURPOSE: Although the 6-minute walk test is commonly used to assess the functional status of patients with severe cardiopulmonary disease, few studies have tested its value in a cardiac rehabilitation (CR) population with milder disease status. The purpose of this study was to examine the validity and reliability of the 6-minute walk in a Phase II/III CR program. METHODS: Ninety-four patients (61 men, 33 women) aged 63 +/- 10 years completed three 6-minute walks on nonconsecutive days. Patients also completed the Duke Activity Status Index (DASI) and the Short Form 36 Health Survey (SF-36). In addition, maximum metabolic equivalents (METs) from a symptom-limited graded exercise test were obtained from files. RESULTS: The 6-minute walk was linearly related to maximum METs (r = 0.687, P < 0.001), supporting the validity of the test. Patients walked significantly farther in each 6-minute walk (F = 19.83, P < 0.001), and strong test-retest reliability was demonstrated (intraclass correlation = 0.97). Distance walked decreased with older age (F = 19.49, P < 0.001), with men walking farther than women (F = 7.19, P < 0.01). The 6-minute walk was moderately correlated with scores from the DASI (r = 0.502, P < 0.001), and the Physical Function subscale of the SF-36 (r = 0.624, P < 0.001). CONCLUSIONS: The 6-minute walk is a valid and reliable method of assessing functional ability in a Phase II/III CR population. A learning effect of 6% was observed over the three walks; however, it is unknown if this learning effect will be retained over time. This test may be particularly valuable to smaller CR centers that want to document functional improvements but do not have access to conventional treadmill tests.

Exercise prescription for patients with pacemakers.

When developing an exercise program for pacemaker patients, basic information about the pacemaker must be understood. Atrial, ventricular, and dual-chamber devices can produce varying exercise responses and impact the exercise prescription. The type of rate adaptive sensor the pacemaker has will affect the nature of heart rate response, and therefore, must be taken into account when prescribing exercise. While rate modulation is used with most chronotropically incompetent patients, individuals with VVI pacemakers will also benefit from regular exercise. Although the value of exercise testing pacemaker-dependent patients for ECG interpretation may be limited, it is useful in determining exercise capacity and ensuring proper pacemaker function. Participation in a supervised exercise training program can greatly enhance the follow-up and management of pacemaker-dependent patients as well as afford them the opportunity to experience the physical and psychologic benefits typically associated with cardiac rehabilitation.

Effects of sensor selection on exercise stroke volume in pacemaker dependent patients.

The effects of sensor selection and sensor blending on the cardiovascular response to graded exercise was evaluated in 10 patients (age 74 +/- 2 yrs; 7 men and 3 women) implanted with a dual sensor rate adaptive VVIR pacemaker (Vitatron Topaz model 515). Patients underwent three graded exercise tests (GXT) with sensor programming randomly assigned. For a given graded exercise text the pacemaker was programmed into activity sensing (ACT), QT sensing, or dual sensing (ACT = QT). Data were recorded at rest and during each stage of the graded exercise text. Oxygen uptake (VO2) was measured continuously using a Q Plex I system. Heart rate (HR), stroke volume (SV), and cardiac output (Qc) were measured by impedance cardiography. Systolic time intervals were calculated from simultaneous recordings of the ECG, phonocardiogram, and the impedance cardiogram. In response to the GXT no differences in peak VO2 were observed across the three sensor settings. Regardless of the sensor setting Qc increased linearly with each increment in VO2. The HR response to ACT only pacing was significantly higher than in the other two pacing conditions. During ACT only pacing SV failed to rise in response to exercise. The increased exercise Qc during QT and ACT = QT pacing were mediated by significant increases in both HR and SV. The QT and dual pacing conditions were also associated with longer diastolic filling times. The data indicate that the mechanisms responsible for the increase Qc during exercise were different for ACT versus ACT = QT or QT sensor-driven pacing.

Heart rate/stroke volume relationship during upright exercise in long-term diabetics.

The changes in stroke volume (SV) during upright exercise were studied in 20 insulin-dependent diabetics (IDDM) and 20 age- and sex-matched controls. None of the diabetics had any cardiovascular symptoms. In addition, tests of autonomic function were conducted in the diabetics, assessing changes in heart rate (HR) during deep breathing and the Valsalva maneuver. During exercise the SV in the controls gradually increased and then remained essentially unchanged until maximum HR was achieved. Seven of the diabetics failed to sustain an initial increase in SV (fall > 15%), eight showed a "delayed" increase in SV, and the remaining five demonstrated an increasing SV over the range from rest to peak exercise. Abnormal autonomic function results were found during deep breathing (four diabetics) and the Valsalva maneuver (four diabetics). Findings indicate that cardiac function could be abnormal in IDDM without evidence of autonomic dysfunction. This abnormality could be due to a specific cardiomyopathy.

The hemodynamic responses to upright exercise after orthotopic cardiac transplant.

The study was undertaken to examine the heart rate (HR) and stroke volume (SV) responses to upright exercise in patients after orthotopic cardiac transplantation (Group A). The findings were compared to data obtained from post-coronary artery bypass surgery patients (Group B) and from healthy subjects (Group C). All three groups (n = 12 in each group) were matched for age and gender. The preexercise HR and blood pressure were significantly higher in Group A (p < 0.05), whereas the SV was significantly lower (41 +/- 4mL.beat-1 vs 63 +/- 3 and 65 +/- 2 mL.beat-1 in Group B and C respectively, p < 0.05). In Group A, at submaximal work loads, the SV was consistently lower than in Groups B and C. During the early phases of exercise, the HR was consistently higher in Group A also. Systemic vascular resistance remained significantly higher in Group A throughout exercise (p < 0.05).

Changes in blood pressure and cardiac output during maximal isokinetic exercise.

This study was undertaken to determine the blood pressure (BP) and cardiac output (Qc) responses to maximal isokinetic exercise. The subjects (n = 5) performed unilateral knee extension/flexion exercise (knee exercise) and unilateral elbow extension/flexion exercise (elbow exercise) at 0.52, 1.57, and 2.62 rads.sec-1. The BP was monitored using a cannula placed in the radial artery. Heart rate (HR), stroke volume (SV), and Qc were measured by impedance cardiography. In response to isokinetic exercise, HR and Qc increased significantly (p less than .01), while the SV did not. The BP response was characterized by significant increases in systolic, diastolic, and mean arterial pressure (MAP) (p less than .01). The Qc and MAP, responses were not influenced by the exercise velocity. The adjustments in HR, MAP, and rate pressure product (RPP) to the elbow exercise were qualitatively similar to those seen during the knee exercise, but the absolute values achieved were smaller (p less than .05). Compared with maximal dynamic exercise, the HR and SV responses to the knee exercises were lower. The MAP response to isokinetic exercise equaled the highest value achieved during dynamic exercise. Findings from the present study suggest that the cardiovascular stress (the increase in HR, MAP, and RPP) associated with isokinetic exercise is independent of the velocity of movement and is proportional to the active muscle mass.

Effects of hydraulic circuit training following coronary artery bypass surgery.

The effect of hydraulic circuit training (HCT) on stroke volume (SV), cardiac output (Qc), aerobic power (peak VO2), and muscular strength and endurance was evaluated in 24 post-coronary artery bypass (CABS) patients (mean age = 52.8 +/- 2.6 yr). All assessments other than muscular strength and endurance were based upon a symptom limited graded exercise test on a bicycle ergometer. Muscular strength and endurance were assessed on a Cybex II isokinetic dynamometer. Sixteen patients were assigned randomly to 8 wk of cycle training or HCT (N = 8 in each). Subjects assigned to cycle training exercised on bicycle ergometers. The HCT group exercised on a three-station circuit, completing three circuits per day. Each circuit consisted of three 20 s work intervals at each station with a 1:1 work:rest ratio. Results from the training groups were compared with results from eight patients who served as a nonexercising control group. Following training the peak VO2 was significantly increased in the training groups (20% and 11% for the cycle and HCT groups, respectively; P less than 0.05). For both training groups, the increase in peak VO2 was associated with increases in SV and Qc and a reduction in heart rate (HR) at submaximal levels of exercise (P less than 0.05). Only the HCT group demonstrated an increase in both muscular strength and endurance during knee and shoulder exercises (P less than 0.05). These findings suggest that a program of HCT can elicit improvements in cardiovascular fitness and muscular strength and endurance in post-CABS patients.

Effect of rate-adapting atrioventricular delay on stroke volume and cardiac output during atrial synchronous pacing.

The need to adjust atrioventricular delay relative to pacing rate in atrial synchronous pacemakers was assessed in eight subjects treated for complete heart block (mean age 61 +/- 3.4 years). First, an inverse relationship between heart rate and PR interval was confirmed in two groups of healthy subjects and one group of patients recovering from myocardial infarction. Due to the limitations of the available pacemakers this relationship could not be precisely reproduced. Subjects with pacemakers performed an initial exercise test on a bicycle ergometer to determine heart rate response; this information was used in part 2 to program atrioventricular delay relative to heart rate. During a second exercise test, a rate-adapting atrioventricular delay was compared to a constant atrioventricular delay of 200 ms at matched heart rates. Cardiac output was measured noninvasively by impedance cardiography. The results of part 1 showed an abnormal pattern in the response of stroke volume to exercise in seven subjects. Part 2 results demonstrated no significant difference (P greater than 0.05) between a rate-adapting atrioventricular delay and a constant delay of 200 ms for heart rate, stroke volume, cardiac output, blood pressure or Borg scale. A trend towards increased stroke volume with a rate-adapting atrioventricular delay was observed. Stroke volume was 13% larger with a rate-adapting atrioventricular delay of 125 ms at a heart rate of 125 beats/min. These results suggest that subjects with atrial synchronous pacemakers have a variable stroke volume response to exercise. It appears that in these subjects the ability to increase heart rate is the key factor for raising cardiac output during exercise.

Long term follow-up after isolated aortic valve replacement.

Between January 1982 and June 1989, 102 consecutive patients (25 women and 77 men) who had isolated aortic valve replacements were reviewed. The overall early operative mortality was 5%. The deaths were related mainly to pump failure and endocarditis. The early operative mortality in younger patients (less than 70 years old) was 3.5% and in the elderly (70 or older) 11%. The overall late mortality was 4%. All of the survivors except three (follow-up by telephone) were seen in follow-up by cardiologists. The mean follow-up was 40 +/- 26 months (range four to 89). Eighty-seven per cent of all patients or 92% of the survivors in the younger population did well following the operation. In the elderly patients, the results were less favorable (P less than 0.025). The overall cumulative survival was 92% at one year and 89% at five years. The actuarial event-free percentage of survivors was 86% at one year and 74% at five years. Aortic valve replacement can be accomplished in symptomatic patients with an acceptable operative mortality. Long term follow-up of these patients showed functional improvement and low mortality.

The influence of high-velocity circuit resistance training on VO2max and cardiac output.

In order to investigate the influence of high-velocity circuit resistance training on maximal aerobic power, maximal stroke volume and cardiac output, and blood lactate removal during recovery, 16 habitually active males were blocked on initial VO2max into either training or control groups. The training group completed two (weeks 1 and 2) or three (weeks 3-6) circuits of 10 variable-resistance hydraulic exercise stations at an exercise: relief ratio of 1:2 on alternate days over six weeks. Angular velocities of movement were maintained at approximately 3.1 rad.s-1. Following training, the VO2max was increased (p less than .01) from 4.32 to 4.68 1.min-1. Maximal stroke volume was increased (p less than .05) from 120 to 129 mL and heart rate response to an absolute submaximal exercise load was decreased (p less than .05) from 153 to 146 beats.min-1. As well, enhanced (p less than .01) removal of lactate from the blood was observed during recovery from exhausting exercise. No changes were observed for control subjects. These results indicate that positive alterations in aerobic and cardiovascular function may be achieved consequent to high-velocity circuit resistance training.

Short-term cardiovascular adaptations to vertical head-down suspension.

Inversion devices have been advocated as means of therapy for patients with low back pain. The present investigation was undertaken to determine the cardiovascular responses to vertical head-down suspension with such a device. Eight men were monitored for three minutes in the upright and supine position, and for ten minutes in the vertical head-down position. Stroke volume (SV), heart rate (HR), cardiac output (QT), segmental arm blood flow (ABF), and segmental leg blood flow (LBF) were measured by impedance plethysmography. Moving from the upright to the supine positions resulted in an SV increase from 93.1 +/- 18.8 to 138.2 +/- 28.2 ml.beat-1 (p less than 0.01). During the first minute of suspension a further increase in SV to a maximum of 178.6 +/- 45.0 ml.beat-1 was noted. By the end of the suspension period, SV had declined to 159.6 +/- 34.2 ml.beat-1. Resumption of the upright position was associated with a reduction in SV to 94.3 +/- 15.8 ml.beat-1. Changes in QT across the supine and vertical head-down positions reflected the changes in SV. The vertical head-down position was also associated with a gradual reduction in both ABF and LBF. These data suggest that the primary effect of inverted suspension was a transient increase in venous return, which requires an effective ventricular response. An element of caution should be exercised in using these devices to avoid aggravating concurrent pathologic conditions.

Response to upright exercise after myocardial infarction.

The left ventricular response to upright bicycle exercise was studied in 39 unselected, non-beta blocked patients (mean(SEM) age 54.2(1.7)yr) (mean(SEM) resting ejection fraction 41.9(2.3)%) 8-10 weeks after myocardial infarction. Nine healthy, age matched, sedentary adult men were studied for comparison (mean(SEM) age 49.8(0.9)yr). The stroke volume and cardiac output were measured by impedance cardiography at rest and after each 3 min workload until symptom limited maximum. The patients were separated into three groups based on stroke volume response to graded exercise. Group 1 (n = 14) had a normal stroke volume response to increasing heart rate. In group 2 (n = 13) stroke volume increased initially then decreased by greater than 15% at a heart rate greater than 100-105 beats.min-1. In group 3 (n = 12) stroke volume failed to increase during exercise. In group 1 cardiac output and mean arterial pressure increased whereas vascular resistance decreased during exercise in a normal fashion. Group 2 had an increased mean arterial pressure and systemic vascular resistance throughout exercise while heart rate increased in a similar fashion to group 1 until work of greater than 70 W was undertaken, at which time heart rate increased in a curvilinear fashion and cardiac output was attenuated. Group 3 had an attenuated cardiac output and a higher heart rate during exercise. In this group of patients systemic vascular resistance failed to decrease normally during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac output measured by impedance cardiography during maximal exercise tests.

The overall accuracy of cardiac output measurements made by impedance cardiography during maximum exercise was studied in man. Initially, the systematic error of the technique was assessed over the range 3.5 to 18 litre . min-1 by comparing with simultaneous measurements of cardiac output made using the direct Fick method. No systemic error was demonstrated in 40 estimations made in 20 subjects. The random error was assessed in 4 subjects in a steady state at rest and during exercise at 80 and 130 W and found to be less than 5% in each subject. The reproducibility of maximum exercise response was assessed in six healthy male subjects (age 26.2 +/- 4.4 years, +/- SEM) who underwent maximum exercise tests twice, 1 week apart, on a bicycle ergometer. Simultaneous recordings of cardiac output and oxygen uptake (VO2) at rest and during each 3 min stage of exercise were made. Highly significant correlations were obtained in the stroke volume (r = 0.84, p less than 0.001), cardiac output (r = 0.98, p less than 0.001) and VO2 (r = 0.98, p less than 0.001) between the two tests. Average maximum cardiac output was 27.0 +/- 1.2 litre . min-1 (+/- SEM) and maximum VO2 was 4.4 +/- 0.2 litre . min-1 (+/- SEM). These results show that measurements of cardiac output were reproducible over one week. Impedance cardiography is non-invasive technique which is as accurate as invasive methods and can be used for maximal exercise testing.