The utility of the oxygen pulse recovery as a marker of the cardiac output response to exercise in patients with chronic heart failure

Abstract

PURPOSE: The cardiac output (CO) response to exercise is a useful marker to grade the prognosis and severity of chronic heart failure (CHF). The recovery of the oxygen pulse (OP) is a non-invasive parameter, which is related to exercise capacity in cardiac patients. However, the relation between OP recovery and the central haemodynamic response to exercise remains to be determined. We hypothesized that an impaired OP recovery is associated with a reduced CO response to exercise in CHF patients. METHODS: Sixty one CHF patients performed cardiopulmonary exercise test with simultaneous measurement of CO. Impaired OP recovery was defined as an overshoot during the first minute of recovery or OP at 1-min recovery as a percentage of peak OP (OPRR ). RESULTS: An OP overshoot was observed in 9% (n = 5) of patients. In these patients, peak CO and VO2 were significantly lower (peak CO 7.9 ± 0.8 versus 11.2 ± 4.3 L/min and peak VO2 14.1 ± 4.7 versus 19.6 ± 5.8 ml min-1 kg-1 ). Mean relative recovery of OP was 78 ± 20%. Slow OP recovery (negative OPRR ) was seen in 13% (n = 8). Peak CO and VO2 were significantly lower in the negative OPRR group (11 ± 4 versus 8 ± 0.7 L/min and 19.7 ± 5.9 versus 14.6 ± 3.7 ml kg min-1 ). There was a significant relation between OPRR and stroke volume (SV) RR (r = .57), as well as between OPRR and a-v O2 diff RR (rs = .4). CONCLUSION: An impaired OP recovery is associated with a reduced CO response to exercise and worse functional status. Therefore, the OP recovery can be used to grade the severity of CHF.