Open AccessLimited value of anaerobic threshold for assessing functional capacity in patients with heart failure
Author(s) -
Miyagi Kyoko,
Asanoi Hidetsugu,
Ishizaka Shinji,
Kameyama Tomoki,
Sasayama Shigetake
Publication year - 1993
Publication title -
clinical cardiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.263
H-Index - 72
eISSN - 1932-8737
pISSN - 0160-9289
DOI - 10.1002/clc.4960160210
Subject(s) - hyperventilation , medicine , anaerobic exercise , heart failure , hypoxemia , cardiology , vo2 max , respiratory failure , heart rate , physical therapy , blood pressure
Exercise tolerance was assessed in 146 patients with cardiac dysfunction in terms of anaerobic threshold (ATge). Patients were divided into four classes according to the peak oxygen uptake: Class A (72 patients) exceeding 1000 ml/min; Class B (27 patients) 800‐999 ml/min; Class C (37 patients) 500‐799 ml/min; and Class D (10 patients) below 500 ml/min. An incidence of the ATge breakpoint was lower in patients of Class C (38%) than in those of either Class B (70%, p < 0.05) or Class A (87%, p < 0.05). The ATge could not be determined in any patients in Class D. The V‐slope method improved the ability to determine ATge by 20%. In Classes C and D, ATge detection was precluded considerably by the fact that the initial workloads of exercise test involved oxygen uptake levels already close to or above the ATge. An oscillatory hyperventilation pattern was also significantly related to failure in defining ATge in Class C patients. Of the 51 patients whose ATge was undetermined, 9 had an atrial septal defect In two of these, exercise‐induced right‐to‐left shunting led to progressive arterial hypoxemia, and the consequent hyperventilation masked the appearance of ATge. Thus, ATge is virtually undetectable in patients with severe heart failure largely because of the early onset of anaerobic metabolism or abnormal ventilatory responses to exercise. Accordingly, the clinical application of ATge in the assessment of functional capacity would be limited to patients with mild to moderate heart failure.