Quantitative evaluation of blood flow distribution to exercising and resting skeletal muscles in patients with cardiac dysfunction using whole-body thallium-201 scintigraphy.
OBJECTIVE
Decreased blood flow to working muscles makes an important contribution to exercise intolerance in patients with chronic heart failure. This study was undertaken to examine whether maldistribution of skeletal muscle blood flow is closely related to exercise intolerance in patients with cardiac dysfunction.


METHODS
Whole-body thallium scintigraphy was performed during one-leg exercise in 11 patients with left ventricular (LV) dysfunction (LV ejection fraction < 45%). Blood flow distribution to the exercising and resting legs was quantified by expressing regional thallium counts as a percentage of the whole-body counts at rest, at the level of anaerobic threshold, and at peak exercise.


RESULTS
At anaerobic threshold, the thallium activity of exercising muscle increased from 4.2 +/- 0.7 to 14.0 +/- 2.5% (p < 0.05) in the thigh and from 1.7 +/- 0.3 to 4.1 +/- 0.9% (p < 0.05) in the calf, compared with the resting value. Consequently, the ratio of thallium activity between exercising and resting legs increased to 2.7 +/- 0.7 (p < 0.05) in the thigh and to 2.3 +/- 0.7 (p < 0.05) in the calf. When plotted as a function of anaerobic threshold, thallium activity of the exercising thigh (r = 0.78, p < 0.05) and the thallium ratio between exercising and resting thigh (r = 0.69, p < 0.05) declined with the reduction of exercise tolerance. These correlations were not observed in calves.


CONCLUSIONS
Whole-body thallium scintigraphy demonstrated a maldistribution of leg blood flow in patients with reduced aerobic exercise capacity, suggesting that this abnormality could play an important role in exercising intolerance in these patients.
Wada
O
O
Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Japan.
Asanoi
H
H
Miyagi
K
K
Ishizaka
S
S
Kameyama
T
T
Ishise
H
H
Seto
H
H
Inoue
H
H
D000328:Adult; D000368:Aged; D015308:Anaerobic Threshold / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology*; D013794:Thallium Radioisotopes; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*
D013794:Thallium Radioisotopes