Author + information
- Pierre Abraham, MD, PhD* (, )
- Guillaume Mahé, MD,
- Antoine Bruneau, MD and
- Georges Leftheriotis, MD, PhD
- ↵*Laboratory for Vascular Investigations, University Hospital, 4 Rue Larrey, 49033 Angers Cedex, 09, France
In their excellent paper, Anderson et al. (1) showed that cellular metabolism correlated better with treadmill exercise results than estimation of muscle perfusion in patients with peripheral artery disease (PAD). Anderson et al. (1) suggested that factors independent of blood flow and located downstream from the obstruction are believed to play an important role in the relative absence of relation of the degree of hemodynamic impairment to functional limitation. Why should only downstream vascular parameters be factors to play a role in this result?
First, in the accompanying editorial, Dewey (2) briefly recalls that PAD may affect various arterial territories (among which the pelvic circulation) further limiting their clinical prognosis. In perspective with the high prevalence (22%) of patients with prior revascularization among the 85 studied patients, it is likely that functional limitation from proximal claudication may have interfered with the expected relationship between calf perfusion and exercise capacity. Indeed, proximal claudication may persist in approximately one-third of PAD patients early after aortobifemoral bypass surgery (3) or be present in a comparable proportion in those who have a patent aortobifemoral bypass with a median delay of 2 years from surgery (4). In these patients as well as those with isolated occlusion of the internal iliac artery, PAD may result in severe functional impairment whereas distal (calf) perfusion is not impaired.
Second, many studies have underlined that the impairment of aerobic and anaerobic capacity is significantly correlated with the severity of anemia. Although blood samples were available in the study of Anderson et al. (1) for cholesterol estimation and inflammatory markers, the evaluation of hemoglobin content is not reported. Anemia is a common comorbid condition in elderly patients. Of 732 consecutive patients admitted to an acute geriatric ward, 24% were found to be anemic (5). The proportion of anemic patients may even be higher in patients with advanced PAD (6).
Lastly, limb pain while walking may be the sole reported symptom of exercise-induced hypoxemia (7). Respiratory parameters at rest may remain in normal limits despite the presence of exercise-induced hypoxemia. Pulmonary disease and vascular disease share a number of common risk factors (age, overweight, tobacco). Not all patients with pulmonary disease have hypoxemia, but 15% of patients with PAD (8,9) have pulmonary disease. Therefore, exercise-induced hypoxemia may be a frequent aggravating cause of exercise intolerance in PAD patients.
As a conclusion, at least the 3 previously suggested “nondownstream” factors should probably be discussed as major causes of the relative absence of relation between the degree of hemodynamic impairment and functional limitation. Integrative (proximal and distal) vascular investigations, as well as estimation of blood oxygen transport capacity and content during exercise, are likely required when one analyzes the relationship between the severity of perfusion impairment in PAD and functional limitation.
- American College of Cardiology Foundation
- Anderson J.D.,
- Epstein F.H.,
- Meyer C.H.,
- et al.
- Dewey M.