Impairment of endothelium-independent vasodilation in patients with hypercalcemia.
OBJECTIVE
Patients with primary hyperparathyroidism (PHPT) and/or hypercalcemia are at increased risk for myocardial ischemia. Whether PHPT is associated with altered endothelium-dependent dilation, vascular smooth muscle cell function, or both is unknown. This study was performed to test the hypothesis that endothelium-dependent, flow-mediated dilation (FMD) and/or endothelium-independent, nitroglycerin-induced dilation (NMD) is impaired in the preclinical phase of vascular disease in patients with PHPT.


METHODS
Twenty-six PHPT patients (mean +/- SD; age 55 +/- 15 y, serum calcium 3.00 +/- 0.37 mmol/l, serum phosphate 0.79 +/- 0.21 mmol/l, iPTH 249 +/- 262 pg/ml) with no evidence of coronary artery disease (CAD) as well as 26 normocalcemic control subjects (CTL; age 51 +/- 12 y) were studied. FMD following reactive hyperemia and NMD after 0.8 mg nitroglycerin (NTG) were assessed in the brachial artery by using high resolution ultrasound (7 MHz).


RESULTS
NMD was impaired in PHPT patients compared to CTL (11.9 +/- 3.9% vs. 15.6 +/- 5.7%; p = 0.012). FMD was similar in both study groups (11.6 +/- 4.6% vs. 12.6 +/- 4.9; NS). The ratio of FMD to NMD was significantly different between PHPT patients and CTL (0.98 +/- 0.19 vs 0.81 +/- 0.25, p = 0.0009). On multiple stepwise regression analysis serum calcium was independently associated with the FMD/NMD ratio (r = 0.34, p = 0.017).


CONCLUSIONS
Endothelium-independent vasodilation is impaired in PHPT patients without clinical evidence of coronary artery disease compared to normocalcemic CTL, while endothelium-dependent dilation was similar in both study groups. Thus, altered arterial reactivity in the course of PHPT may predominantly involve the arterial media and not the endothelium as observed previously in patients with various stages of atherosclerosis.
Neunteufl
T
T
Department of Cardiology, University of Vienna, Austria.
Katzenschlager
R
R
Abela
C
C
Kostner
K
K
Niederle
B
B
Weidinger
F
F
Stefenelli
T
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001916:Brachial Artery / Q000000981:diagnostic imaging; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D006961:Hyperparathyroidism / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D005996:Nitroglycerin / Q000494:pharmacology; D015588:Observer Variation; D012039:Regional Blood Flow; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D014665:Vasodilator Agents; D005996:Nitroglycerin