Temporal heterogeneity of endothelium-dependent and -independent dilatation of brachial artery in patients with coronary artery disease.
BACKGROUND
Endothelial function is routinely assessed with high frequency ultrasound of the brachial artery. Fixed time points (1' post-occlusion and 3' post-nitrate) are commonly used to assess dynamic changes in brachial artery diameter. The underlying assumption is the lack of variability in temporal response to both endothelium-dependent and -independent stimuli.


OBJECTIVE
To evaluate the temporal course of endothelium-dependent (flow-mediated) and endothelium-independent (nitrate-induced) vasodilation of the brachial artery in patients with coronary artery disease (CAD) using high resolution (10 MHz) ultrasound.


METHODS
Thirty-seven patients with angiographically assessed CAD were prospectively enrolled in the study. End-diastolic, two-dimensional, long axis ultrasonographic images of the brachial artery were digitally stored on-line every 10 s, from baseline up to 4' during flow-mediated and up to 7' during 300 micrograms sublingual nitrate-induced vasodilation of the brachial artery.


RESULTS
The mean percent endothelium-dependent flow-mediated maximal dilation (FMD) measured at 60 s was lower than the mean peak FMD (4.8 +/- 4.1 vs. 6.6 +/- 5.2%; p < 0.01). By 60 s only eight patients (35%) reached their maximum FMD response. The mean time to reach peak FMD was 87 +/- 33 s. The mean time for the peak nitrate dilation was 291 +/- 73 s. The peak nitrate-induced percent dilation was higher than that measured at 3 min (12.2 +/- 6.7 vs. 5.4 +/- 4.5%; p < 0.001). By 190 s, only four patients (11%) reached their maximum nitrate response.


CONCLUSIONS
The routinely used measurement time points for evaluation of FMD and endothelium-independent vasodilation may not be adequate to detect the peak responses of individual patients with CAD.
Department of Medicine and Cardiology Center, Albert Szent-Györgyi Medical Faculty, University of Sciences, Szeged, Hungary.
Attila
A
Pálinkás
Eszter
E
Tóth
Lucia
L
Venneri
Fausto
F
Rigo
Miklós
M
Csanády
Eugenio
E
Picano
D000368:Aged; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000494:pharmacology; D015588:Observer Variation; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects
D009566:Nitrates