Short Term Hemodynamic Effects of Controlled Slow Breathing With Biofeedback in Patients With Heart Failure

Heart Failure (HF) is a growing and challenging public health concern in the United States.
Current data suggest that there are about 5 million heart failure patients in this country
with an additional 550,000 patients being diagnosed with this syndrome each year for the
first time. Despite the significant advances in the management strategy of heart failure
patients in the last 1-2 decades, there are about 1 million hospital admissions each year
for Acute Decompensated Heart Failure (ADHF), almost double the number seen 15 years ago.
The readmission rate for these patients at 6-month following discharge approaches about 50%
with estimated 5-year mortality of 50%. Approximately, $23 billion are spent for the
inpatient management of HF patients with another $40 billion for outpatient care. This
prevailing situation mandates further exploration of novel therapeutic targets to treat this
complex disease.

Chronic HF is accompanied by a sustained elevation in sympathetic nervous system activity,
which is thought to be an important component in the pathophysiology and progression of the
disease. HF patients also show abnormal breathing pattern with an increased respiratory rate
and a lower tidal volume. Faster respiratory rate is associated with higher levels of
sympathetic activity and potentiation of the chemoreflex response to hypoxia and
hypercapnia. The relationship between sympathetic activity and spontaneous breathing rate is
independent of age, body mass index, physical activity levels, percentage of body fat, or
blood pressure. The arterial baroreflex sensitivity is also reduced in patients with heart
failure. All these factors contribute to the distressing symptoms of fatigue, dyspnea and
exercise intolerance in these patients.

Yoga trainees learn to breathe slowly, at a rate of about six breaths per minute, mobilizing
in sequence the diaphragm and the upper and the lower chest. A handful of studies in normal
subjects undergoing intensive training in yogic breathing techniques have demonstrated a
marked improvement in cardiac hemodynamic parameters (cardiac output, cardiac index, stroke
volume etc.), but such studies have not been conducted in patients with heart failure.

The purpose of our study is to evaluate the changes in cardiac hemodynamic parameters
(cardiac output, cardiac index and thoracic fluid content) in patients with acute heart
failure, chronic ambulatory heart failure and normal healthy subjects after a trial of
controlled slow breathing. Subjects would undergo non-invasive measurement of cardiac
hemodynamics while spontaneously breathing. They would then be given instructions in slow
breathing at a rate of 6 to 10 breaths per minute and asked to practice it for some time
using heart rate variability as biofeedback mechanism. Hemodynamic measurements would be
repeated during and after the trial of slow breathing. The difference between these
measurements would then be statistically analyzed. We hypothesize that even a short trial of
controlled slow breathing using a biofeedback mechanism in patients with HF would produce
significant favorable improvement in cardiac hemodynamics.