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Title: Exercise prescription and cardiac rehabilitation programme design for high-risk patients
Author: Doherty, Patrick Joseph
ISNI:       0000 0004 2705 3479
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2002
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Implantable cardioverter defibrillators are highly effective in the management of life threatening ventricular arrhythmias and implanted for secondary and primary prevention of sudden cardiac death. However, 40% of patients fail to adapt to implantation, developing phobic anxiety states, depression and a fear of arrhythmia and defibrillator therapy (shock) during physical activity. Antecedent behaviour associated with defibrillator therapy and physical activity contributes to a sedentary lifestyle and a concomitant reduction in functional capacity (FC), both of which are associated with an increase in all cause mortality and a greater morbidity. A specific cardiac rehabilitation (CR) programme was developed to address these needs. Method: An initial aspect of the study reviewed 2000 conventional clinical exercise tests (ET) to developed criteria for ET selection. Sixteen patients were randomly selected from 34 who agreed to attend CR and all consented to be included in the study. The mean age was 57.7 years (SD 10.3), mean defibrillator implant period was 20.4 months (SD 13.8) and the mean left ventricular ejection fraction was 38% (SD 17). FC was defined as the outcome from sub maximal exercise tests using an incremental walking treadmill protocol. ET termination was based on a target heart rate of appropriately 75% of age-adjusted maximum heart rate or within 10 beats of the defibrillator detection threshold or the patients desire to stop. The reliability of the new ET protocol was incorporated within the study design. Patients attended CR exercise sessions twice weekly for 12 weeks and performed mainly aerobic exercise using a circuit-training approach with four intensity levels. The prescription, monitoring and adjustment of exercise intensity were achieved by telemetry heart rate and 'rate of perceived exertion'. Heart rate monitors were worn for all exercise sessions. Once weekly home exercise and regular walking was encouraged between sessions. Educational sessions on diet, medication, psychology and the benefits of an active lifestyle were provided. The primary outcome measures were ET results and the Hospital Anxiety&Depression scale scores. Analysis of variance was utilised statistically. Results: All 16 patients completed pre-base and baseline ETs with a mean ET time (mm:ss) increase of 01:04 (SD 01:10), a 3rd ET with 8 patients found no significant increase in ET time. Thirteen patients completed the CR exercise programme and showed significant increases in the intensity of exercise performed without significantly increasing heart rate or blood pressure. A baseline comparison between compliant and non-compliant patients found that the non-compliant patients were younger with greater FC and less psychological distress. Eleven patients completed a further evaluation 12-weeks post CR; two were unable to attend due to exacerbation of co-morbidity. ET time (mm:ss) post CR showed a mean improvement of 01:02 (95% CI, 01:36 to 00:27 p= 0.002). Clinically significant anxiety and depression scores existed at baseline with mean anxiety scores of 13.4 (SD 3.6) reduced post CR to 8.1 (SD 3.6) (95% CI, 3.5 to 7.0, p=0.001). Mean depression scores of 10.0 (SD 3.4) reduced to 6.7 (SD 3.0) (95% CI, 2.0 to 4.4, p=0.002) post CR. Improvements in ET times and HADS scores were maintained at 12 week. No defibrillator therapy occurred during ETs or the exercise sessions. Conclusion: The new treadmill ET protocol was reliable after a formal pre-test and considered safe and effective due to no complications or defibrillator therapy. Exercise circuit training with heart rate and rate of perceived exertion monitoring was safe and lead to increased exercise capacity. Efficacy of cardiac rehabilitation was evident with improvement in functional capacity and psychosocial health and the outcomes were maintained at 12 weeks without the use of formal exercise. Generalisations beyond this pilot study are limited and a multi-centred control trial is needed to establish the external validity of the intervention effect.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available