Clinical Significance of a Spiral Phenomenon in the Plot of CO2Output Versus O2Uptake During Exercise in Cardiac Patients

Nagayama, Osamu;
Koike, Akira; Himi, Tomoko; Sakurada, Koji; Kato, Yuko; Suzuki, Shinya;
Sato, Akira; Yamashita, Takeshi; Wasserman, Karlman; Aonuma, Kazutaka.
The American Journal of Cardiology, March 2015, Vol. 115 Issue: Number
5 p691-696, 6p;

Abstract: A spiral phenomenon is sometimes noted in the
plots of CO2output (VCO2) against O2uptake (VO2) measured during
cardiopulmonary exercise testing (CPX) in patients with heart failure
with oscillatory breathing. However, few data are available that
elucidate the clinical significance of this phenomenon. Our group
studied the prevalence of this phenomenon and its relation to cardiac
and cardiopulmonary function. Of 2,263 cardiac patients who underwent
CPX, 126 patients with a clear pattern of oscillatory breathing were
identified. Cardiopulmonary indexes were compared between patients who
showed the spiral phenomenon (n = 49) and those who did not (n = 77).
The amplitudes of VO2and VCO2oscillations were greater and the phase
difference between VO2and VCO2oscillations was longer in the patients
with the spiral phenomenon than in those without it. Patients with the
spiral phenomenon also had a lower left ventricular ejection fraction
(43.4 ± 21.4% vs 57.1 ± 16.8%, p <0.001) and a higher level of brain
natriuretic peptide (637.2 ± 698.3 vs 228.3 ± 351.4 pg/ml, p = 0.002).
The peak VO2was lower (14.5 ± 5.6 vs 18.1 ± 6.3, p = 0.002), the slope
of the increase in ventilation versus VCO2was higher (39.8 ± 9.5 vs
33.6 ± 6.8, p <0.001), and end-tidal PCO2both at rest and at peak
exercise was lower in the patients with the spiral phenomenon than in
those without it. In conclusion, the spiral phenomenon in the
VCO2-versus-VO2plot arising from the phase difference between VCO2and
VO2oscillations reflects more advanced cardiopulmonary dysfunction in
cardiac patients with oscillatory breathing.