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Biofeedback in the treatment of heart disease

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Abstract

Biofeedback is a method of training subjects to regulate their own physiology using feedback from physiologic sensors connected to an output display. Biofeedback-assisted stress management (BFSM) incorporates the physiologic signals with instructions on stress management. The goal of BFSM training is to give subjects the tools to control their own mental and physiologic reactions, leading to improved health and wellness. In cardiovascular disease, overactivation of the sympathetic component of the autonomic nervous system and psychologic stress together negatively affect quality of life and clinical status. BFSM targets both areas. We hypothesize that this intervention can be used in cardiovascular disease to improve clinical status and quality of life, as well as interfere with disease progression. We are conducting trials of BFSM in heart failure and stable coronary artery disease. Preliminary data suggest that use of BFSM by heart failure patients may actually cause cellular and molecular remodeling of the failing heart in the direction of normal. We are comparing the effects of BFSM with usual care in patients with stable coronary artery disease, testing the hypothesis that the intervention will decrease both sympathetic hyperarousal and activation of the inflammatory cascade. Since heart rate variability is abnormal in both cardiovascular disease and depression, and since BFSM has been successfully used to change heart rate variability, we also expect this intervention to have a positive impact on the depression that often accompanies cardiovascular disease.


 

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BIOFEEDBACK: WHAT IS IT?

The term “biofeedback” refers to the instrumentation or training process that allows biologic information to be recorded, displayed, and communicated back to an individual, allowing the individual to make adjustments in physiologic processes that may enhance health or performance. The biofeedback display is analogous to a mirror, in which physiologic processes can be observed and adjusted much as one might adjust a hairstyle or a tie.

In our work with cardiovascular disease patients, biofeedback is a training process that involves a subject or patient, a biofeedback coach or therapist, and state-of-the-art biofeedback equipment. For biofeedback training to be effective, the subject who is trying to learn the skill must be engaged and willing to practice, the coach must be trained in psychophysiology, and the equipment must display accurate readings in real time, allowing the subject to monitor and change physiologic reactions appropriately. The coach teaches the subject about the physiologic parameters, establishes target ranges, and helps the subject learn how to move the physiologic parameters in the right direction.1,2

Training often begins with a session in which a brief mental stress test is followed by a period of relaxation while physiologic parameters are recorded and displayed. This process helps the subject to understand the link between mental processes and physiologic arousal.

Biofeedback training can involve a number of physiologic modalities, including those that reflect autonomic nervous system arousal, such as skin conductance and heart rate variability, and those that are not strictly correlated with autonomic activity, such as surface muscle tension. Each physiologic parameter is recorded by a specific sensor, and all sensors are noninvasive. Sensors feed signals into a computer, where they are processed and amplified, and subjects are able to view the output on a computer screen.

Typically, in our work, there is one screen for the subject, on which a single parameter can be displayed, observed and discussed, and another screen for the coach, on which all parameters are displayed simultaneously. During a single session of biofeedback training, the coach may choose to work on a single parameter or switch between parameters, depending on how much progress is being made with each. In our work with patients, we generally train to simple parameters first, such as respiratory rate, finger temperature, and skin conductance, moving on to surface muscle tension, heart rate, and eventually heart rate variability, which is a more complex concept and more easily understood later in the training process.

It is important that the subject receive positive reinforcement for changing the physiologic parameters, and if the subject struggles too long with one parameter, it is generally useful to go back to a different parameter, where success may be more easily experienced. Ideally, by the end of six to eight training sessions, the subject will be able to make progress on all physiologic parameters, which will track together over time.

BIOFEEDBACK-ASSISTED STRESS MANAGEMENT

Pure biofeedback training consists of operant conditioning. That is, the subject learns to regulate his or her physiology in the right direction because of the feedback, which can be as simple as a pleasant image appearing on a computer screen or as complicated as a car moving faster around a racetrack; pure biofeedback involves changing physiology in response to positive reinforcement of some sort.

In practice, we generally employ biofeedback-assisted stress management (BFSM) rather than pure biofeedback. With BFSM, the subject learns to change physiology in the direction of health and wellness by learning techniques of stress management. The coach teaches the subject various relaxation techniques, such as slow and rhythmic breathing, guided imagery, progressive muscle relaxation, mindfulness, assertiveness, and how to change negative thought patterns. With regular practice, the subject learns to change the physiologic parameters by relaxing the body. For example, instead of instructing the subject to “increase your finger temperature” and assume that the subject will achieve this because doing so will make the light bulb on the screen glow more intensely, the BFSM coach may instead talk with the subject about eliminating stressful thoughts, learning to relax, and the fingers warming in response to the body relaxing.

We distinguish between techniques of stress management, some of which are mentioned above, and psychotherapy, which can certainly be effectively combined with biofeedback, but which we do not provide in our research studies. Coupling stress management techniques with biofeedback helps the subject change physiologic parameters in the direction of wellness and acquire tools that can be used in everyday life when stressful events arise. The objective of BFSM training is not just to change physiology, but also to change the way subjects respond to stressful events in daily life; ie, react to fewer events, react less intensely when they do react, and recover more quickly.

BIOFEEDBACK-ASSISTED STRESS MANAGEMENT IN CARDIOVASCULAR DISEASE

We are currently studying the effects of BFSM in patients with cardiovascular disease, including both heart failure and stable coronary artery disease. Patients with cardiovascular disease often are functionally limited, and they also experience psychologic distress related to physical limitations and other life stressors. Both the physical limitations and the psychologic distress impact quality of life. We hypothesize that BFSM will teach our patients techniques of stress management, both mental and physiologic, that will help relieve their psychologic distress and improve their quality of life. BFSM will also potentially decrease the overactivation of the sympathetic branch of the autonomic nervous system, which is common in cardiovascular disease, and correspondingly upregulate the contribution of the parasympathetic branch of the autonomic nervous system, which should be beneficial.3

Figure. Proposed model by which biofeedback-mediated stress management interferes with symptoms and progression of cardiovascular disease. NS = nervous system

We postulate that the decreased psychologic distress and improved balance of autonomic nervous system input to the heart will result in improved clinical status and biologic remodeling of the heart and blood vessels away from disease progression and toward health and wellness (Figure).

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