The severity of COPD is found to be correlated to likelihood of developing abnormal heart rate recovery and chronotropic incompetence during exercise.
A recent study found a strong link between the severity of a patient's chronic obstructive pulmonary disease (COPD) and the patient's likelihood of heart rate malfunction during exercise (Abnormal heart rate recovery and chronotropic incompetence on exercise in chronic obstructive pulmonary disease, 2013. Mansi Gupta, et al.). Heart rate malfunction during exercise was assessed through abnormal heart rate recovery and chronotropic incompetence. Abnormal heart rate recovery is a delayed drop in heart rate following exercise, defined as less than or equal to a 12 beat per minute decline in heart rate one minute after termination of exercise. Chronotropic incompetence means that the heart cannot reach a target heart rate during exercise.
In America, the leading cause of COPD is smoking; however, in countries with less stringent pollution regulation, pollution may be the leading cause of COPD. The aforementioned study took place in India, where biomass fuel exposure causes the majority of COPD in women. To control for this, the study only used male smokers. COPD can come in two forms: chronic bronchitis and emphysema. Symptoms of COPD include cough, fatigue, respiratory infection, dyspnea (shortness of breath) and wheezing. The severity of COPD in this study was measured using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria and body mass index, air flow obstruction, dyspnoea and exercise capacity (BODE) index. The figure below depicts ill-formed alveoli characteristic of emphysema.
The proportion of patients with an abnormal heart rate recovery following exercise was much higher in patients with high levels of COPD as measured with the BODE index. The GOLD criteria demonstrated that as COPD severity increased, the proportion of patients with abnormal heart rate recovery increased. The figure below illustrates this data.
In addition, the proportion of COPD patients with chronotropic incompetence, an inability to reach a target heart rate during exercise, increased with COPD severity as defined by the GOLD criteria and BODE index. A strong level of correlation was observed. The figure below demonstrates that the study data suggests there is a link between COPD and chronotropic incompetence during exercise.
Issues with the chronotropic function (chronotropic comes from the Greek word for time, chronos, and refers to heart rate controls) of the cardiac system generally suggest autonomic nervous system dysfunction. The autonomic nervous system accelerates heart rate with input from the sympathetic nervous system and depresses heart rate with the parasympathetic nervous system. The authors acknowledge that smoking may cause both autonomic nervous system dysfunction and COPD. However, COPD is a strong predictor of cardiovascular disease. Irregular breathing would affect regulation of the autonomic nervous system. For example, poor lung function from COPD would trigger the autonomic nervous system to increase the breathing rate, but the heart would not demand a similar increase in beat rate. Incongruity between heart rate and breathing rate autonomic nervous system innervation is not normally observed in healthy patients.
The best advice for COPD patients is to quit smoking and/or physically refrain from smoky or polluted environments. It is important to realize that COPD not only affects the pulmonary system, but the cardiovascular system as well. By knocking out the pulmonary and cardiovascular system, COPD is a double-edged sword for those who enjoy exercise.