Comparison of Cardiac Pacing Modes in Patients With Chronic Obstructive Pulmonary Disease – Discussion
Dyspnea with exertion is a commonly recognized complaint in patients with lung disease. An increasing perception of shortness of breath with exercise is consistent with severe lung disease and frequently results in a fear of exertion that not only limits any activity requiring exertion, but daily living activities as well. The limitation of physical activities also leads to deconditioning, which then further compromises the patient’s ability to exercise. It has been shown that individual perceptions of dyspnea are very subjective and correlate better with work of breathing rather than level of hypoxemia. Due to the relative subjectivity of the complaint, “I feel short of breath with exercise” and the fact that most patients will modify their life-styles to accommodate increasing dyspnea with exertion, providing medical management that will keep these patients active and clinic ally stable is a challenge. Any adjunct that can help to optimize oxygen delivery is valuable in the treatment and rehabilitation of these patients. buy birth control
In this study, those patients with chronic lung disease who required cardiac pacing performed significantly better with a DDRR as compared with WIR. There was a significant improvement in exercise duration as well as a decrease in the ventilatory equivalents for oxygen at all levels of exercise. The improvement in exercise duration is important as it suggests an increased exercise tolerance. One must also be careful not to overlook the significance of the decreases seen in the ventilatory equivalent for oxygen at all levels of exercise. This decrease is consistent with a trend toward improvement in AT, suggesting a decrease in lactic acid production throughout exercise and an improvement in the efficiency of oxygen delivery with this mode. Perhaps even more important is that decreases in ventilator)’ effort or work of breathing will affect the patient’s perception of dyspnea. All of the patients with COPD we tested stated that they felt less short of breath during exercise with the DDDR pacing mode compared with the WIR mode, which is consistent with the decreases noted in ventilatory equivalents for oxygen at all levels of exercise.
In formulating strategies for the treatment of patients with COPD, therapies that contribute to the efficient utilization and delivery of oxygen are a priority. Based on the results of this study, DDDR pacing offers a distinct improvement in hemodynamic function and exercise tolerance in those patients with chronic lung disease who also require cardiac pacing therapy, despite the increased complexity and higher costs associated with these systems. In the updated Guidelines for Pacemaker Implantation from the American College of Cardiology/American Heart Association task force, dual chamber pacemakers have been recommended for those patients in whom maintenance of AV synchrony will result in a significant improvement in their quality of life. Maintenance of atrial transport, when allowed by the intrinsic atrial rhythm, has also been recommended by the British Pacing and Electrophysiology Group.
It seems reasonable to expect that the improved cardiopulmonary function and decreased perception of dyspnea with DDDR pacing as demonstrated in this short-term study will translate into an improved quality of life in the patient with COPD requiring cardiac pacing over that achievable with WIR pacing.