Peripheral flow response to transient arterial forearm occlusion does not reflect myocardial perfusion reserve.
BACKGROUND
Ultrasonographic evaluation of systemic arterial function is widely available, and a close relation of endothelial function in the coronary and brachial arteries has been documented. It is unknown, however, whether a similar correlation exists for their 2 microcirculatory territories and thus whether assessment of the systemic microcirculation can be used similarly as a surrogate marker of myocardial perfusion.


RESULTS
Twenty-three patients with documented coronary artery disease (CAD; 66+/-9 years old, 18 men), 16 patients with syndrome X (SX; 56+/-5 years old, 13 women), and 45 healthy control subjects (C; 34+/-9 years old, 22 men) were studied. Myocardial perfusion was measured at rest and after dipyridamole (0.56 mg. kg(-1). min(-1) over 4 minutes) by PET, and brachial artery blood flow was measured at rest and after transient forearm ischemia by standard Doppler ultrasound techniques. Dipyridamole increased myocardial perfusion in all groups (mL. g(-1). min(-1): CAD, 0.89+/-0.27 versus 1.62+/-0.67, P:<0.001; SX, 0.82+/-0.16 versus 1.67+/-0.49, P:<0.001; and C, 0.82+/-0.15 versus 2.32+/-0.64, P:<0.001). Postocclusion forearm flow increased similarly in all groups (CAD, 52+/-18 versus 174+/-77 mL/min, P:<0.001; SX, 49+/-29 versus 202+/-82 mL/min, P:<0.001; and C, 61+/-34 versus 229+/-108 mL/min, P:<0.001). No significant correlations were found between peripheral and myocardial microcirculatory beds for either resting flow, hyperemic flow, or flow reserve in any of the groups (r(2)<0.1, P:=NS).


CONCLUSIONS
The peripheral perfusion responses to transient forearm ischemia do not correlate with dipyridamole-induced myocardial hyperemia. The lack of correlation indicates different mechanisms of microvascular activation or regulation and confirms that extrapolations between findings in the 2 vascular beds are not suitable.
Department of Cardiology B, Aarhus University Hospital, University of Aarhus, Aarhus, Denmark. mboe@dadlnet.dk
M
M
Bøttcher
M M
MM
Madsen
J
J
Refsgaard
N H
NH
Buus
I
I
Dørup
T T
TT
Nielsen
K
K
Sørensen
D000328:Adult; D000368:Aged; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001794:Blood Pressure; D001916:Brachial Artery / Q000502:physiology; D005260:Female; D005542:Forearm; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000503:physiopathology; D010477:Perfusion; D013223:Statistics as Topic; D014463:Ultrasonography; D014664:Vasodilation